Electronics Systems And Technologies

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Catherine Halcomb
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1. AM stands for

Explanation

AM stands for Amplitude Modulation. This is a method of transmitting signals by varying the amplitude of the carrier wave in accordance with the intensity of the signal being sent. In AM, the amplitude of the carrier wave is changed to represent the information being transmitted, such as sound or data. This modulation technique is commonly used in broadcasting and is known for its simplicity and ability to carry audio signals over long distances.

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Electronics Systems And Technologies - Quiz

Priority Level: High (ECE) & Low (ECT)

2. VHF stands for the ____________________ frequency band.

Explanation

VHF stands for the Very High frequency band. This term is commonly used in telecommunications and radio broadcasting to refer to a specific range of frequencies between 30 and 300 MHz. The term "Very High" accurately describes the frequency range covered by VHF, which is higher than the frequencies used for AM and FM radio broadcasting.

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3. The smallest element or part of a picture is a

Explanation

A pixel is the smallest element or part of a picture. It refers to a single point in a digital image or on a display screen. Pixels are used to represent and display images in various forms, such as photographs, videos, and computer graphics. Each pixel contains information about its color and intensity, and when combined with other pixels, they create the complete image.

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4. What type of satellite appears to stay in one position in the sky?

Explanation

A geostationary satellite appears to stay in one position in the sky because it orbits the Earth at the same speed and direction as the Earth's rotation. This allows the satellite to remain fixed relative to a specific location on the Earth's surface, making it ideal for applications such as weather monitoring, communications, and television broadcasting. HEO (Highly Elliptical Orbit) satellites have highly elliptical orbits and do not stay in one position in the sky. Geomagnetic satellites study Earth's magnetic field and LEO (Low Earth Orbit) satellites have low orbits and also do not stay in one position in the sky.

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5. QAM stands for:

Explanation

QAM stands for Quadrature Amplitude Modulation. This is a modulation scheme used in telecommunications to transmit digital signals over an analog channel. It combines both amplitude modulation and phase modulation to encode the digital information into the amplitude and phase of the carrier signal. By using different combinations of amplitude and phase, multiple bits can be transmitted simultaneously, increasing the data rate. Therefore, Quadrature Amplitude Modulation accurately describes the technique used in this modulation scheme.

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6. SWR stands for

Explanation

SWR stands for Standing Wave Ratio. Standing wave ratio is a measure of how well a transmission line is matched to its load. A low SWR indicates a good match, while a high SWR indicates a poor match. SWR is important in radio frequency systems, as a high SWR can result in power loss and damage to the equipment.

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7. Which generation of cellular network technology preceded 5G?

Explanation

4G is the correct answer because it is the generation of cellular network technology that came before 5G. 4G, also known as LTE (Long-Term Evolution), provided faster data speeds and improved network capacity compared to its predecessor, 3G. It enabled the widespread adoption of mobile internet and streaming services on smartphones and other connected devices. 5G is the next generation of cellular technology, promising even faster speeds, lower latency, and greater capacity for supporting emerging technologies like autonomous vehicles and the Internet of Things.

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8. FSK stands for:

Explanation

FSK stands for Frequency-Shift Keying. This is a digital modulation technique where the frequency of the carrier signal is varied in accordance with the digital input signal. In FSK, different frequencies are used to represent different binary states, typically 0 and 1. This modulation technique is commonly used in telecommunications and data transmission systems to transmit digital information over analog channels.

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9. What is the modulation index of an FM-phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency when the modulating frequency is 1000 Hz?

Explanation

The modulation index of an FM-phone signal is determined by dividing the maximum frequency deviation by the modulating frequency. In this case, the maximum frequency deviation is given as 3000 Hz and the modulating frequency is 1000 Hz. Dividing 3000 Hz by 1000 Hz gives a modulation index of 3.

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10. TDM stands for

Explanation

TDM stands for Time-Division Multiplexing. This technique is used in telecommunications to transmit multiple signals over a single communication channel by dividing the available time slots into smaller units and allocating them to each signal. Each signal takes turns in using the channel, thus allowing multiple signals to be transmitted simultaneously. This method is commonly used in applications such as telephone systems and digital subscriber lines (DSL) to efficiently utilize the available bandwidth.

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11. HDTV stands for

Explanation

HDTV stands for High-definition television, which refers to a television system that provides a higher resolution and clearer image quality compared to standard-definition television. It offers a sharper, more detailed picture with enhanced color reproduction and a wider aspect ratio. HDTV has become the standard for modern televisions, providing a more immersive and enjoyable viewing experience for users.

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12.  It allows many signals to share a channel.

Explanation

Multiplexing is the correct answer because it refers to the process of combining multiple signals or data streams into a single channel or transmission medium. By doing so, it allows many signals to share the same channel, optimizing the use of available resources and increasing efficiency. This technique is commonly used in telecommunications and networking to transmit multiple signals simultaneously over a single channel, saving time and resources.

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13. What is antenna bandwidth?

Explanation

Antenna bandwidth refers to the frequency range over which an antenna is able to meet a specific performance requirement. This means that the antenna is designed and optimized to operate effectively within a certain range of frequencies, and its performance may vary outside of this range. The antenna's ability to transmit and receive signals efficiently is directly related to its bandwidth.

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14. IP stands for:

Explanation

IP stands for Internet Protocol. The Internet Protocol is a set of rules that governs the format and transmission of data packets over the internet. It is responsible for routing data packets from the source to the destination device, ensuring reliable and efficient communication between different networks. IP addresses are used to uniquely identify devices on a network and enable the delivery of data packets to the correct destination. Therefore, Internet Protocol is the correct answer as it accurately represents the purpose and function of IP in computer networks.

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15. FDM stands for

Explanation

FDM stands for Frequency-Division Multiplexing. This technique is used to transmit multiple signals simultaneously over a single communication channel by dividing the available bandwidth into multiple frequency bands. Each signal is allocated a different frequency band, allowing them to be transmitted simultaneously without interfering with each other. FDM is commonly used in telecommunications systems to maximize the utilization of the available bandwidth and efficiently transmit multiple signals over a single communication medium.

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16. A technique used by codes to convert an analog signal into a digital bit stream is known as

Explanation

Pulse code modulation (PCM) is a technique used by codes to convert an analog signal into a digital bit stream. In PCM, the amplitude of the analog signal is sampled at regular intervals and each sample is assigned a binary code. This binary code represents the amplitude of the signal at that particular point in time. PCM is commonly used in telecommunications and audio applications, as it allows for accurate and reliable transmission and storage of analog signals in a digital format.

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17. Thermal noise is caused by the random motions of ____________________ in a conductor.

Explanation

Thermal noise is caused by the random motions of electrons in a conductor. As electrons move through a conductor, they collide with atoms and other electrons, creating random fluctuations in the electrical signal. These fluctuations result in thermal noise, which can interfere with the desired signal and reduce the overall signal quality. Therefore, the correct answer is electrons.

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18. HTTP stands for:

Explanation

HTTP stands for Hypertext Transfer Protocol. It is a protocol used for transmitting hypertext (text that includes links) over the internet. It is the foundation of data communication for the World Wide Web. HTTP allows web browsers to send requests to web servers and receive responses back, enabling the retrieval and display of web pages. It is a standardized set of rules and conventions that govern the communication between clients (such as web browsers) and servers (such as web servers).

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19. All cell phone systems are

Explanation

Full duplex means that a device can transmit and receive data simultaneously. In the context of cell phone systems, full duplex allows users to talk and listen at the same time, just like in a regular phone conversation. This is achieved through the use of separate frequencies for sending and receiving data. Therefore, the correct answer is full duplex because it accurately describes the capability of cell phone systems to handle simultaneous two-way communication.

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20. What are the principal frequencies that appear at the output of a mixer circuit?

Explanation

The principal frequencies that appear at the output of a mixer circuit are the two input frequencies along with their sum and difference frequencies. This is because a mixer circuit combines two input frequencies to produce an output signal that contains both the sum and difference of the input frequencies. Therefore, the correct answer is the first option.

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21. What is the name of the Philippines first microsatellite?

Explanation

Diwata-1 is the correct answer because it was the first microsatellite launched by the Philippines. The name "Diwata" means "fairy" or "goddess" in Filipino, symbolizing the country's aspiration to reach for the stars. Diwata-1 was launched on March 23, 2016, and it played a significant role in promoting space science and technology in the Philippines. It was designed to capture high-resolution images of the Earth's surface and monitor weather patterns, as well as conduct experiments in space technology and atmospheric research.

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22. What is the name of the Philippines second microsatellite?

Explanation

Diwata-2 is the correct answer because it is the second microsatellite launched by the Philippines. The name "Diwata" is derived from a Filipino word meaning "fairy" or "goddess," symbolizing the country's aspiration to harness space technology for the benefit of its people. Diwata-2 was launched in October 2018 and is primarily used for Earth observation and disaster management purposes.

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23. A radio signal's ____________________ is the distance it travels in one cycle of the carrier.

Explanation

The correct answer is "wavelength". In the context of a radio signal, wavelength refers to the distance the signal travels in one complete cycle of the carrier wave. It is a fundamental property of any wave, including radio waves, and is typically measured in meters or other units of length. The wavelength of a radio signal determines its frequency and is important in various aspects of signal propagation and communication.

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24. The brain of any computer system is

Explanation

The CPU (Central Processing Unit) is often referred to as the brain of a computer system. It is responsible for executing instructions, performing calculations, and managing the flow of data within the system. The CPU consists of multiple components, including the ALU (Arithmetic Logic Unit), which performs mathematical and logical operations, the control unit, which coordinates and controls the activities of the CPU, and the memory, which stores data and instructions for the CPU to access and process. Therefore, the CPU is the correct answer as it encompasses all these essential components.

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25. PSK stands for:

Explanation

Phase-Shift Keying (PSK) is a digital modulation technique where the phase of the carrier signal is varied to represent binary data. In PSK, different phase states are assigned to different binary symbols, typically 0 and 1. By shifting the phase of the carrier signal, the receiver can detect the changes in phase and decode the binary data. Therefore, PSK is the correct expansion for the acronym PSK.

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26. Which of the following features is not currently available with current cell phone technology?

Explanation

The given question asks for a feature that is not currently available with current cell phone technology. Among the options, a digital camera, GPS, and MP3 player are all features that are commonly found in cell phones today. However, indefinite battery life is not currently possible with current cell phone technology. This means that cell phones still have limitations when it comes to battery life and require regular charging.

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27. Which of the following is often determined using a Smith chart?

Explanation

A Smith chart is a graphical tool used in electrical engineering to analyze and design transmission lines and impedance matching networks. It is particularly useful for determining the impedance and standing wave ratio (SWR) values in transmission lines. By plotting complex impedance values on the Smith chart, engineers can easily calculate and visualize the impedance and SWR at any point along the transmission line. This helps in optimizing the performance and efficiency of the transmission line by ensuring proper impedance matching.

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28. When two or more signals share a common channel, it is called

Explanation

Multiplexing is the correct answer because it refers to the process of combining multiple signals into a single channel or transmission medium. In this scenario, when two or more signals share a common channel, they are being multiplexed. This allows for efficient use of the channel and enables multiple signals to be transmitted simultaneously. Sub-channeling, signal switching, and SINAD are not applicable in this context and do not accurately describe the situation of multiple signals sharing a common channel.

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29. A balanced load can be connected to an unbalanced cable

Explanation

A balanced load can be connected to an unbalanced cable by using a "balun". A balun is a device that converts between balanced and unbalanced signals. It allows for the connection of a balanced load, which has two equal and opposite signals, to an unbalanced cable, which has only one signal conductor. The balun ensures that the balanced load is properly matched to the unbalanced cable, preventing signal distortion or loss.

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30. How does the spread spectrum technique of frequency hopping work?

Explanation

In frequency hopping spread spectrum technique, the frequency of the transmitted signal is rapidly changed according to a pseudorandom sequence. This sequence is also known to the receiving station, allowing it to synchronize with the transmitter and hop frequencies in the same pattern. This technique helps in spreading the signal energy across a wide bandwidth, making it more resistant to interference and jamming.

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31. A mobile operating system developed by Apple Inc. and distributed exclusively for Apple hardware.

Explanation

iOS is the correct answer because it is a mobile operating system developed by Apple Inc. and is exclusively distributed for Apple hardware. It is known for its user-friendly interface, seamless integration with other Apple devices, and a wide range of applications available on the App Store. iOS is known for its strong security features and regular updates, making it a popular choice among Apple users.

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32. What is the radiation resistance of an antenna?

Explanation

The radiation resistance of an antenna refers to the value of a resistance that would dissipate the same amount of power as that radiated from the antenna. This means that it represents the theoretical resistance that would absorb all the power radiated by the antenna, without any losses. It is an important parameter to consider when designing and analyzing antennas, as it helps in determining the efficiency and performance of the antenna system.

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33. What is a folded dipole antenna?

Explanation

A folded dipole antenna is a type of antenna that consists of a half-wave dipole with an additional parallel wire connecting its two ends. This additional wire increases the electrical length of the antenna, allowing it to resonate at a lower frequency than a regular half-wave dipole. The folded dipole antenna offers improved impedance matching and increased bandwidth compared to a standard dipole antenna.

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34. Which of the following modes is used to send image data over telephone lines?

Explanation

Fax is the correct answer because it is a mode specifically designed for sending image data over telephone lines. Fax machines convert images into signals that can be transmitted over telephone lines and then reassembled into images on the receiving end. This mode allows for the transmission of documents, photographs, and other visual materials over long distances using standard telephone lines.

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35. Unwanted ads and solicitations via email fall into the category of

Explanation

Unwanted ads and solicitations via email are commonly referred to as spam. Spam refers to unsolicited and often irrelevant or inappropriate messages sent in bulk to a large number of recipients. These messages are typically sent for advertising purposes or to spread malware. Spam can be a nuisance and can also pose security risks to users if they contain malicious links or attachments.

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36. EIRP stands for:

Explanation

EIRP stands for the Effective Isotropic Radiated Power. It is a measure of the power that an antenna radiates in a specific direction. Isotropic refers to an idealized antenna that radiates power equally in all directions. The EIRP takes into account the gain of the antenna as well as the power input to the antenna, providing a standardized measurement of the power radiated by an antenna.

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37. Codec stands for:

Explanation

Codec stands for Coder-Decoder. A codec is a device or software that encodes and decodes digital data. It is used to compress and decompress audio, video, and other types of data for transmission and storage. The term "codec" is derived from the words "coder" and "decoder" because it involves the process of encoding data into a compressed format and decoding it back to its original form.

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38. NBFM stands for:

Explanation

NBFM stands for Narrowband FM. Narrowband FM refers to a type of frequency modulation used in radio communications. It is characterized by a narrow bandwidth, which allows for efficient use of the frequency spectrum. Unlike wideband FM, narrowband FM occupies less space on the spectrum, making it suitable for applications where limited bandwidth is available or where multiple channels need to be accommodated. Narrowband FM is commonly used in two-way radio systems, wireless communication devices, and amateur radio operations.

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39. What is the modulation index of an FM-phone signal having a maximum carrier deviation of plus or minus 6 kHz when modulated with a 2 kHz modulating frequency?

Explanation

The modulation index of an FM-phone signal is determined by dividing the maximum carrier deviation by the modulating frequency. In this case, the maximum carrier deviation is plus or minus 6 kHz and the modulating frequency is 2 kHz. Therefore, the modulation index is 6 kHz divided by 2 kHz, which equals 3.

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40. A complete communication system must include

Explanation

A complete communication system requires a transmitter to send the information, a receiver to receive the information, and a channel through which the information is transmitted. The transmitter converts the information into a signal that can be sent through the channel, while the receiver decodes the signal to retrieve the original information. The channel serves as the medium through which the signal is transmitted, such as a wire, fiber optic cable, or wireless spectrum. Therefore, all three components are necessary for a communication system to function properly.

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41. Radio broadcasting is a familiar example of

Explanation

Frequency multiplexing is the correct answer because radio broadcasting involves transmitting multiple signals simultaneously over different frequencies. Each station is assigned a specific frequency, and by using frequency multiplexing, these signals can be combined and transmitted through the airwaves. This allows multiple radio stations to coexist without interfering with each other.

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42. Which of the following is a disadvantage of 5G?

Explanation

5G has a disadvantage of limited coverage. This means that the network may not be available in all areas, especially in rural or remote locations. Limited coverage can restrict the accessibility and availability of 5G services to a smaller population, making it less reliable and less convenient for those who do not have access to the network.

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43. CRC stands for:

Explanation

CRC stands for Cyclic Redundancy Check. It is an error-detecting code used in digital networks and storage devices to ensure the integrity of data transmission. The CRC algorithm generates a fixed-size checksum, which is appended to the data being transmitted. The receiver recalculates the checksum and compares it with the received checksum. If they match, it indicates that the data was received without errors. If they don't match, it suggests that errors may have occurred during transmission, and the data needs to be resent.

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44. What must be done to prevent standing waves on an antenna feed line?

Explanation

To prevent standing waves on an antenna feed line, the antenna feed-point impedance must be matched to the characteristic impedance of the feed line. When the impedance of the feed-point matches the characteristic impedance of the feed line, it ensures that the energy is efficiently transferred from the transmitter to the antenna without any reflections. This prevents the formation of standing waves, which can cause signal degradation and loss of power.

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45. What is microstrip?

Explanation

Microstrip refers to precision printed circuit conductors that are positioned above a ground plane. These conductors are designed to provide constant impedance interconnects specifically at microwave frequencies.

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46. DSP stands for:

Explanation

DSP stands for Digital Signal Processor. This is a specialized microprocessor that is designed to perform efficient and fast mathematical calculations on digital signals. It is commonly used in audio and video processing, telecommunications, and image processing applications. The term "Digital Signal Processor" accurately describes the function and purpose of this technology.

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47. DSL stands for:

Explanation

DSL stands for Digital Subscriber Line. It is a type of high-speed internet connection that uses existing telephone lines to transmit digital data. DSL provides faster download and upload speeds compared to traditional dial-up connections. It allows users to access the internet while simultaneously using their telephone line for voice calls.

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48. ITU is an abbreviation for:

Explanation

ITU stands for International Telecommunications Union. This organization is a specialized agency of the United Nations that focuses on information and communication technologies. It is responsible for coordinating international telecommunications standards, allocating global radio spectrum, and promoting the development of affordable and accessible communication services worldwide.

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49. The 'B' in Hartley's Law stands for

Explanation

Hartley's Law is a formula used to calculate the maximum data transfer rate of a communication channel. It states that the maximum data rate is equal to the bandwidth of the channel multiplied by the number of signal levels used to represent data. In this context, the 'B' in Hartley's Law stands for bandwidth, which refers to the range of frequencies that can be transmitted over a channel. Therefore, the correct answer is bandwidth.

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50. "Signaling" is used to indicate:

Explanation

"Signaling" refers to the process of transmitting information or indications between devices or systems. In the context of telecommunication, signaling is used to indicate various conditions. The on-hook/off-hook condition refers to whether a telephone handset is placed on the cradle (on-hook) or lifted (off-hook) to initiate or receive a call. A busy signal indicates that the called party's line is currently engaged. Ringing is the indication of an incoming call. Therefore, all of the given choices accurately represent different uses of signaling in telecommunication.

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51. The highest layer of the ionosphere is

Explanation

The F layer is the highest layer of the ionosphere. It is located at an altitude of about 200 to 600 kilometers above the Earth's surface. This layer is responsible for reflecting high frequency radio waves back to the Earth, allowing long-distance communication. The F layer is further divided into two sub-layers, F1 and F2, with the F2 layer being the highest and most important for long-distance communication. Therefore, the F layer is the correct answer as it is the highest layer of the ionosphere.

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52. Cellular radio systems divide the service area into many smaller areas known as

Explanation

Cellular radio systems divide the service area into smaller areas known as "cells." These cells are created to efficiently manage and allocate the available radio frequency spectrum. Each cell is served by a base station, and as users move from one cell to another, they are handed off to the neighboring cell's base station. This allows for seamless connectivity and efficient use of resources in a cellular network.

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53. The velocity factor of a transmission line depends on

Explanation

The velocity factor of a transmission line is a measure of how fast an electrical signal can travel through the line compared to the speed of light in a vacuum. It is affected by various factors, including temperature, skin effect, relative permittivity of the dielectric, and resistance. However, the main factor that determines the velocity factor is the relative permittivity of the dielectric material used in the transmission line. The higher the relative permittivity, the slower the signal travels through the line. Therefore, the correct answer is the relative permittivity of the dielectric.

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54. Which of the following can be calculated using a Smith chart?

Explanation

A Smith chart is a graphical tool used to analyze and calculate the impedance along transmission lines. It helps in visualizing the complex impedance and determining the reflection coefficient, standing wave ratio, and other parameters along the transmission line. By plotting the impedance values on the Smith chart, engineers can easily calculate and analyze the impedance variations along the transmission line, making it a useful tool for impedance matching and designing transmission line networks.

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55. The frequency band of the FM Broadcast is: 

Explanation

The correct answer is 88 - 108 MHz. This frequency band is commonly used for FM (Frequency Modulation) radio broadcasting. FM radio stations transmit signals within this frequency range, allowing for high-quality audio transmission. This range is widely accepted and used internationally for FM broadcasting due to its ability to provide clear and reliable signals.

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56. TDM stands for:

Explanation

TDM stands for Time-Division Multiplexing. This technique is used in telecommunications to transmit multiple signals simultaneously over a single communication link by dividing the available time into different time slots. Each signal is allocated a specific time slot, and the signals are interleaved in a cyclic manner. This allows multiple signals to share the same transmission medium without interfering with each other.

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57. Broadband LANs:

Explanation

Broadband LANs encompass all of the given choices. They modulate the data onto a carrier, which is a technique used to transmit information over a communication channel. They also use coaxial cables, which are commonly used in broadband networks for their high bandwidth capacity. Additionally, broadband LANs are provided by cable TV companies for Internet access, as cable companies often offer broadband internet services to customers. Therefore, all of the choices are correct in describing broadband LANs.

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58. TEM stands for:

Explanation

TEM stands for Transverse Electromagnetic. This term refers to a type of electromagnetic wave that has both electric and magnetic field components perpendicular to the direction of propagation. In a TEM wave, the electric field and magnetic field oscillate in planes perpendicular to each other and to the direction of wave propagation. This type of wave is commonly used in various applications, such as in transmission lines and waveguides.

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59. What are the typical characteristic impedances of coaxial cables used for antenna feed lines at amateur stations?

Explanation

Coaxial cables used for antenna feed lines at amateur stations typically have characteristic impedances of 50 and 75 ohms. The characteristic impedance is the ratio of voltage to current in a transmission line, and it is important for matching the impedance of the cable to the impedance of the antenna and the transmitter. A mismatch in impedance can result in signal reflections and loss of signal strength. The 50 and 75 ohm characteristic impedances are commonly used in amateur radio applications and are compatible with many types of antennas and transmitters.

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60. ASCII stands for:

Explanation

ASCII stands for American Standard Code for Information Interchange. ASCII is a character encoding standard that represents text in computers and other devices. It uses a 7-bit encoding scheme, which allows for the representation of 128 different characters, including letters, numbers, punctuation marks, and control characters. ASCII is widely used in computer systems and communication protocols to ensure compatibility and interoperability between different devices and software applications.

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61. What current flows equally on all conductors of an unshielded multi-conductor cable?

Explanation

Common-mode current refers to the current that flows in the same direction on all conductors of an unshielded multi-conductor cable. This type of current is caused by external sources such as electromagnetic interference or ground potential differences. It can cause interference and noise in the cable, affecting the performance of the connected devices. By understanding and managing common-mode current, measures can be taken to minimize its effects and ensure proper functioning of the cable and connected equipment.

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62. What standing wave ratio will result from the connection of a 50-ohm feed line to a non-reactive load having a 50-ohm impedance?

Explanation

When a 50-ohm feed line is connected to a non-reactive load with a 50-ohm impedance, the standing wave ratio will be 1:1. This means that there will be no reflected power and the impedance will be perfectly matched, resulting in maximum power transfer between the feed line and the load.

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63. A non-optimum value for SWR will cause

Explanation

A non-optimum value for SWR (Standing Wave Ratio) refers to a mismatch between the impedance of the transmission line and the load. This leads to the formation of standing waves, where the energy is reflected back and forth between the load and the source. These standing waves cause a loss of power to the load as some of the energy is not effectively transferred. Additionally, the non-optimum SWR results in higher voltage peaks on the cable, which can lead to increased stress and potential damage to the equipment. Therefore, all of the given choices are correct.

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64. TDMA stands for:

Explanation

TDMA stands for Time Division Multiple Access. This is a method used in telecommunications to allow multiple users to share the same frequency channel by dividing it into different time slots. Each user is assigned a specific time slot during which they can transmit their data. This technique is commonly used in cellular networks to increase the capacity and efficiency of the system.

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65. Manchester coding:

Explanation

Manchester coding is a biphase code that has a level transition in the middle of every bit period. It is known for providing strong timing information. Therefore, the correct answer is "all of the choices" because all the statements mentioned are true about Manchester coding.

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66. What term describes station output, taking into account all gains and losses?

Explanation

Effective radiated power is the term that describes station output, taking into account all gains and losses. It is a measure of how much power is radiated by an antenna, considering factors such as antenna efficiency, feedline losses, and mismatch losses. Effective radiated power is important in determining the coverage area and signal strength of a radio station.

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67. Orbital disturbances of a geosynchronous satellite are caused by the

Explanation

The correct answer is "All the choices" because orbital disturbances of a geosynchronous satellite can be caused by the gravitational forces exerted by the moon, sun, and earth. The gravitational pull from each of these celestial bodies can affect the satellite's orbit and cause it to deviate from its intended path. Therefore, all of the choices listed can contribute to orbital disturbances of a geosynchronous satellite.

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68. The more information per second you send, the ____________________ the bandwidth required.

Explanation

The more information per second you send, the greater the bandwidth required. This is because bandwidth refers to the maximum amount of data that can be transmitted in a given amount of time. So, if you are sending more information per second, you will need a larger bandwidth to accommodate the increased data transmission.

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69. Most LANs:

Explanation

All of the choices are correct because most LANs indeed use UTP cable, are based on Ethernet, and use CSMA/CD. UTP cable is commonly used for LAN connections due to its affordability and flexibility. Ethernet is the most widely used LAN technology, providing a standardized set of rules for communication between devices. CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is a protocol used in Ethernet LANs to manage access to the network and detect collisions. Therefore, all of these choices accurately describe characteristics of most LANs.

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70. In which mode of PM does the peak power level of the pulses vary?

Explanation

PAM stands for Pulse Amplitude Modulation. In PAM, the peak power level of the pulses varies. This means that the amplitude or height of the pulses changes to represent the information being transmitted. By varying the peak power level, different levels or values can be encoded and decoded, allowing for the transmission of analog or digital signals. PAM is commonly used in applications such as digital audio transmission and digital communication systems.

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71. Oscillators whose frequencies are controlled by an external input voltage are generally referred to as

Explanation

Voltage-controlled oscillators (VCOs) are oscillators that have their frequencies controlled by an external input voltage. This means that the frequency of the oscillator can be adjusted by varying the input voltage. VCOs are commonly used in various applications such as frequency synthesizers, phase-locked loops, and modulation circuits. Therefore, the correct answer is voltage-controlled oscillators.

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72. The SC in SSB SC stands for:

Explanation

The SC in SSB SC stands for "suppressed-carrier". In Single Sideband (SSB) modulation, one of the carrier frequencies is suppressed or removed to reduce bandwidth and increase efficiency. This type of modulation is commonly used in radio communications to transmit voice or data signals. Therefore, the correct answer is "suppressed-carrier".

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73. FTP stands for:

Explanation

FTP stands for File Transfer Protocol, which is a standard network protocol used to transfer files from one host to another over a TCP-based network, such as the internet. It allows users to upload, download, and manage files on remote servers. FTP is widely used in web development, as it provides a convenient way to transfer files between a local computer and a web server. It is important to note that the other options - File Transport Protocol, File Test Procedure, and Fast Transport Packet - do not accurately represent the acronym FTP.

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74. A circuit that converts an instantaneous value of analog voltage into a binary number is the

Explanation

An A/D converter, or analog-to-digital converter, is a circuit that converts an instantaneous value of analog voltage into a binary number. This conversion is necessary when dealing with digital systems that can only process binary data. The A/D converter samples the analog voltage at regular intervals and assigns a corresponding binary value based on the voltage level. This allows the analog signal to be represented in a digital format, enabling further processing and analysis by digital circuits.

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75. Which of the following is a type of private telephone system?

Explanation

A PBX (Private Branch Exchange) is a type of private telephone system that is commonly used within organizations to manage incoming and outgoing calls. It allows for internal communication between different extensions within the organization and also connects to external telephone lines. A PBX system provides features such as call routing, call forwarding, voicemail, and conference calling, making it an essential tool for efficient communication within a business or institution.

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76. Which of the following indicates the relative strengths of the signal and the noise in a communication system?

Explanation

The signal-to-noise ratio indicates the relative strengths of the signal and the noise in a communication system. It represents the ratio of the power of the signal to the power of the noise. A higher signal-to-noise ratio indicates a stronger signal compared to the noise, resulting in better quality and clarity of the communication.

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77. The part, or parts, of a sinusoidal carrier that can be modulated are

Explanation

The correct answer is "its amplitude, frequency, and phase angle." In modulation, the carrier signal is modified by changing its amplitude, frequency, and phase angle to carry the information signal. Amplitude modulation (AM) changes the amplitude of the carrier signal, frequency modulation (FM) changes the frequency, and phase modulation (PM) changes the phase angle. Therefore, all three components (amplitude, frequency, and phase angle) can be modulated to transmit information.

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78. Which of the following is a Yagi antenna design variable that could be adjusted to optimize forward gain, front-to-back ratio, or SWR bandwidth?

Explanation

All of these choices are correct because the physical length of the boom, the number of elements on the boom, and the spacing of each element along the boom are all design variables that can be adjusted to optimize forward gain, front-to-back ratio, or SWR bandwidth in a Yagi antenna. By adjusting these variables, the performance of the antenna can be optimized for specific requirements and objectives.

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79. What is the cause of auroral activity?

Explanation

Auroral activity is caused by the interaction between charged particles from the Sun and the Earth's magnetic field in the E layer of the atmosphere. When these charged particles, such as electrons and protons, are accelerated and redirected by the Earth's magnetic field, they collide with atoms and molecules in the E layer, causing them to emit light and create the auroras. The interaction between the solar wind and the Van Allen belt occurs in the F2 layer and is not directly responsible for auroral activity. An extreme low-pressure area in the polar regions and meteor showers do not play a significant role in causing auroras.

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80. When a transmitter is connected to a resistor instead of an antenna, the resistor is called:

Explanation

When a transmitter is connected to a resistor instead of an antenna, the resistor is called a dummy load. A dummy load is used to simulate the impedance that an antenna would provide to the transmitter. It allows the transmitter to be tested and adjusted without actually radiating the signal. The resistor dissipates the power that would have been transmitted, preventing it from being radiated as electromagnetic waves. Dummy loads are commonly used in testing and troubleshooting radio equipment.

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81. What is the advantage of including parity bits in ASCII characters?

Explanation

Including parity bits in ASCII characters allows for the detection of certain types of errors. Parity bits are used to check for errors during transmission by adding an extra bit to each character. This bit is set to either 0 or 1 based on the number of 1s in the character. If the number of 1s is odd, the parity bit is set to 1, and if it is even, the parity bit is set to 0. During reception, the parity bit is checked, and if it does not match the calculated parity, an error is detected. This helps in ensuring the accuracy of the transmitted data.

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82. Microwave resonators are used in:

Explanation

Microwave resonators are used in all of the choices mentioned. Microwave oscillators require resonators to generate and control microwave signals. Microwave narrow band amplifiers use resonators to select and amplify a specific range of microwave frequencies. Microwave frequency meters use resonators to accurately measure microwave frequencies. Therefore, all of the given choices require the use of microwave resonators.

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83. Which of the following light sources cannot be used in fiber-optic systems?

Explanation

Incandescent lamps cannot be used in fiber-optic systems because they emit light in a wide range of wavelengths, which makes it difficult to transmit the light through the fiber-optic cables. Fiber-optic systems require light sources with a narrow wavelength range, such as semiconductor lasers and LEDs, to efficiently transmit the light signals through the fibers. Incandescent lamps do not meet this requirement, making them unsuitable for use in fiber-optic systems.

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84. An antenna made up of a driven element and one or more parasitic elements is generally referred to as a

Explanation

A Yagi antenna is made up of a driven element (which is connected to the transmitter or receiver) and one or more parasitic elements (which enhance the antenna's performance). This type of antenna is commonly used for high-gain and directional applications, such as in television reception or long-distance communication. The Yagi antenna was invented by Japanese engineer Hidetsugu Yagi and his colleague Shintaro Uda in the 1920s, and it has since become a popular choice for its simplicity and effectiveness.

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85. What is an isotropic antenna?

Explanation

An isotropic antenna is a theoretical antenna that radiates or receives electromagnetic waves equally in all directions. It is used as a reference for antenna gain, which is a measure of how well an antenna converts input power into radiated power in a particular direction. By comparing the gain of an actual antenna to the gain of an isotropic antenna, the performance of the actual antenna can be evaluated.

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86. The lowest-level layer in ISO OSI is called the:

Explanation

The lowest-level layer in the ISO OSI model is the physical layer. This layer is responsible for the actual transmission of data over the physical medium, such as cables or wireless signals. It deals with the electrical, mechanical, and functional aspects of the physical connection between devices. The physical layer defines characteristics like voltage levels, data rates, and physical connectors. It ensures that the bits sent from one device are received correctly by the other device.

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87. Public-key encryption:

Explanation

Public-key encryption is a cryptographic system that allows secure communication between parties. It uses a pair of keys, a public key for encryption and a private key for decryption. This technology enables the use of digital signatures, which provide authentication and integrity to digital documents. Additionally, public-key encryption can be used to convey symmetric keys securely, ensuring confidentiality in data transmission. Lastly, it avoids the "password problem" associated with traditional encryption methods, where the sender and receiver need to share a common password. Therefore, all of the choices mentioned in the question are correct explanations for public-key encryption.

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88. To couple a coaxial line to a parallel-wire line, it is best to use a

Explanation

A balun is the best option to couple a coaxial line to a parallel-wire line. A balun, short for balanced-unbalanced, is a device that converts between balanced and unbalanced signals. In this case, it can convert the unbalanced coaxial line signal to a balanced signal suitable for the parallel-wire line. This ensures efficient transfer of signals between the two types of transmission lines without causing reflections or impedance mismatches. A directional coupler, quarter-wave transformer, or slotted line may not provide the same level of impedance matching and signal conversion as a balun in this scenario.

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89. Shot noise is generated in

Explanation

Shot noise is generated in transistors and diodes. Shot noise is a type of electronic noise that occurs due to the discrete nature of electric current. It is caused by the random arrival of electrons or holes at a particular point in a circuit. Transistors and diodes are active electronic components that involve the movement of charge carriers, making them susceptible to shot noise. Resistors and copper wire, on the other hand, do not involve the movement of charge carriers in the same way, so they do not generate shot noise. Similarly, a loudspeaker is a passive component that converts electrical signals into sound waves and does not generate shot noise.

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90. Inmarsat stands for:

Explanation

Inmarsat stands for International Maritime Satellite Organization. This organization provides satellite communications services to the maritime industry, ensuring reliable and efficient communication for ships at sea.

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91. The original signal being transmitted from the earth station to the satellite is called the

Explanation

The original signal being transmitted from the earth station to the satellite is called the uplink.

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92. If an AM signal is modulated with audio having frequencies up to 5 kHz, then what is the complete signal bandwidth?

Explanation

When an AM signal is modulated with audio frequencies up to 5 kHz, the signal bandwidth is determined by adding the highest frequency of the audio signal to the carrier frequency. In this case, the carrier frequency is typically around 5 kHz, so adding the highest audio frequency of 5 kHz gives a total bandwidth of 10 kHz. Therefore, the correct answer is 10 kHz.

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93. Which is a possible polarization for an electromagnetic wave?

Explanation

The possible polarization for an electromagnetic wave can be vertical, horizontal, or circular. This means that the electric field of the wave can oscillate in any of these directions. Therefore, all of the choices given - vertical, horizontal, and circular - are possible polarizations for an electromagnetic wave.

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94. What standing wave ratio will result from the connection of a 50-ohm feed line to a non-reactive load having a 10-ohm impedance?

Explanation

When a 50-ohm feed line is connected to a non-reactive load with a 10-ohm impedance, the standing wave ratio (SWR) can be calculated by dividing the highest impedance (50 ohms) by the lowest impedance (10 ohms). In this case, the SWR is 5:1, indicating that the highest impedance is five times greater than the lowest impedance.

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95. Which of the following is a system of delivering the TV signal to home receivers by way of a coaxial cable?

Explanation

Cable TV is a system of delivering the TV signal to home receivers by way of a coaxial cable. This means that the TV signal is transmitted through a cable that is connected to the home receiver, allowing viewers to access a variety of channels and programming. Unlike satellite TV, which uses a satellite dish to receive the TV signal, cable TV relies on a physical cable connection. VHF and UHF antennas, on the other hand, are used to pick up over-the-air broadcast signals, not cable signals.

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96. Why does the radio-path horizon distance exceed the geometric horizon?

Explanation

The radio-path horizon distance exceeds the geometric horizon because of downward bending caused by density variations in the atmosphere. These variations cause the radio waves to curve downwards, allowing them to travel further than they would in a straight line. This phenomenon is known as atmospheric refraction.

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97. The standard that describes Ethernet-type networks is:

Explanation

The correct answer is IEEE 802.3. IEEE 802.3 is the standard that describes Ethernet-type networks. This standard specifies the physical and data link layer protocols for wired Ethernet networks. It defines the characteristics of the Ethernet frame format, as well as the rules for data transmission and collision detection on the network. EIA 232, IEEE 488.1, and CCITT ITU-E are not related to Ethernet-type networks.

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98. A transponder is a satellite equipment which

Explanation

A transponder is a satellite equipment that performs multiple functions. It receives a signal from an Earth station, amplifies the signal, changes the frequency of the received signal, and then retransmits the signal. Therefore, all of the given choices accurately describe the functions of a transponder.

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99. What is the wireless technique that uses thin, inexpensive tags or labels that contain passive radio circuits which can be queried by a remote wireless interrogation unit?

Explanation

RFID stands for Radio Frequency Identification, which is a wireless technique that uses thin, inexpensive tags or labels containing passive radio circuits. These tags can be queried by a remote wireless interrogation unit, allowing for easy identification and tracking of objects or individuals. Unlike HP IrD, IrDA, and IDRF, RFID is specifically designed for this purpose and widely used in various industries for inventory management, access control, and other applications.

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100. Character codes include:

Explanation

The correct answer is "all of the choices" because character codes include alphanumeric characters, data link control characters, and graphic control characters. This means that character codes encompass a wide range of characters, including letters, numbers, special control characters used in data communication, and graphic characters used for formatting and display purposes.

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101. What is the velocity factor of a transmission line?

Explanation

The velocity factor of a transmission line is the ratio of the velocity of the wave in the transmission line to the velocity of light in a vacuum. This factor is used to calculate the propagation delay of signals in the transmission line and is important for accurately timing and synchronizing signals in communication systems. By dividing the velocity of the wave in the transmission line by the velocity of light in a vacuum, we can determine how much slower or faster the wave travels in the transmission line compared to the speed of light.

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102. The path from earth to a satellite is called the

Explanation

The path from Earth to a satellite is called the uplink because it refers to the transmission of data or signals from a ground station on Earth to the satellite in space. This communication link allows for the transmission of information, such as commands or data, from the ground station to the satellite. The uplink is an essential part of satellite communication systems as it enables the exchange of information between Earth and the satellite.

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103. The two basic specifications for a receiver are:

Explanation

The two basic specifications for a receiver are the sensitivity and the selectivity. Sensitivity refers to the ability of the receiver to detect weak signals, while selectivity refers to its ability to separate desired signals from unwanted interference. These two specifications are crucial in determining the overall performance and efficiency of a receiver. A highly sensitive receiver can pick up even faint signals, while a receiver with good selectivity can filter out unwanted noise and interference, allowing for clear and accurate reception of the desired signals.

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104. Mathematically, a spectrum is represented by a

Explanation

A spectrum is mathematically represented by a Fourier series. A Fourier series is a mathematical tool used to represent a periodic function as a sum of sine and cosine functions. It allows us to decompose a complex waveform into its individual frequency components. This is particularly useful in analyzing signals in fields such as physics, engineering, and signal processing.

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105. Frame Relay:

Explanation

The correct answer is "all of the choices" because Frame Relay is indeed faster than X.25, as it uses a simplified protocol that reduces overhead and processing time. Additionally, Frame Relay does less error checking than X.25, as it relies on the underlying network to handle error detection and correction. Lastly, Frame Relay allows for variable length packets, which means it can efficiently transmit data in different packet sizes based on the network's capacity and requirements. Therefore, all the given statements accurately describe the characteristics of Frame Relay.

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106. The first geostationary satellite launched in 1965 was called

Explanation

The correct answer is EARLY BIRD (Intelsat-I). EARLY BIRD, also known as Intelsat-I, was the first geostationary satellite launched in 1965. It was developed by NASA and operated by Intelsat, an international satellite communication organization. EARLY BIRD revolutionized global communication by providing the first live television broadcasts, telephone calls, and data transmissions between continents. Its successful launch and operation paved the way for future geostationary satellites, enabling worldwide telecommunications and shaping the modern communication landscape.

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107. It is an umbrella term for a number of standards organizations which develop protocols for mobile telecommunications.

Explanation

The correct answer is 3rd Generation Partnership Project (3GPP). This organization is responsible for developing protocols for mobile telecommunications. It is an umbrella term for various standards organizations that work together to create standards for mobile networks, including 2G, 3G, 4G, and 5G technologies. The other options mentioned in the question, such as 2GPP, 4GPP, and 5GPP, are not correct as they do not exist.

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108. How does ARQ accomplish error correction?

Explanation

ARQ, or Automatic Repeat reQuest, accomplishes error correction by requesting a retransmission if errors are detected. This means that if errors are found in the received data, the receiver sends a request to the sender to resend the data. This process continues until error-free data is received. By requesting retransmission, ARQ ensures that the errors in the data are corrected and the correct data is received by the receiver.

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109. A frequency-selective circuit designed to pass some frequencies and reject others is a(n)

Explanation

A filter is a frequency-selective circuit that allows certain frequencies to pass through while blocking or attenuating others. It is designed to shape the frequency response of a signal by either allowing only specific frequencies to pass (bandpass filter), blocking certain frequencies (bandstop filter), or allowing a range of frequencies to pass while attenuating others (low-pass or high-pass filter). Filters are commonly used in audio systems, communication systems, and electronic devices to remove unwanted frequencies and enhance the desired signal. Therefore, a filter is the correct answer in this case.

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110. Which type of atmospheric structure can create a path for microwave propagation?

Explanation

Temperature inversion is a type of atmospheric structure where the temperature increases with altitude instead of decreasing. This inversion layer acts as a barrier, trapping pollutants and preventing vertical mixing of air. It can create a path for microwave propagation because microwaves are able to travel through this stable layer without being scattered or absorbed, allowing for long-distance communication and radar detection.

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111. The job of the carrier is to get the information through the 

Explanation

The job of the carrier is to get the information through the channel. In the context of communication systems, a carrier wave is used to transport the information signal through a channel, such as a wire or air. The carrier wave is modulated or altered in some way to carry the information signal, which can then be received and demodulated at the destination. The channel is the medium through which the carrier wave travels, allowing the information to be transmitted from one point to another.

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112. AGC stands for:

Explanation

AGC stands for Automatic Gain Control. This term refers to a technique used in electronics and telecommunications to automatically adjust the gain (amplification) of a signal. It is commonly used in audio systems to maintain a consistent volume level by reducing the gain when the input signal is too strong and increasing it when the signal is too weak. AGC helps to prevent distortion and maintain a desirable signal-to-noise ratio.

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113. ADSL stands for:

Explanation

ADSL stands for Asymmetrical Digital Subscriber Line. This technology allows for high-speed data transmission over existing telephone lines. The term "asymmetrical" refers to the fact that the download speed is typically much faster than the upload speed. This is suitable for most internet users who tend to download more data than they upload. ADSL has been widely adopted for residential and small business internet connections due to its cost-effectiveness and compatibility with existing infrastructure.

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114. What occurs when an excessive amount of signal energy reaches a mixer circuit?

Explanation

When an excessive amount of signal energy reaches a mixer circuit, it can cause distortion and interference. This leads to the generation of spurious mixer products, which are unwanted frequencies that mix with the desired frequencies. These spurious products can degrade the quality of the signal and cause interference with other nearby circuits or systems.

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115. With AM which of the following conveys no information?

Explanation

The carrier signal in amplitude modulation (AM) does not convey any information itself. It is simply a constant signal that is modulated by the information-bearing signal. The information is contained in the sidebands, which are the upper and lower frequency components created by the modulation process. Therefore, the carrier signal conveys no information.

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116. The difference between the upper and lower frequency limits of a signal or the equipment operation range is the

Explanation

Bandwidth refers to the range of frequencies that a signal or equipment can handle or transmit. It represents the difference between the upper and lower frequency limits. A wider bandwidth allows for the transmission of more information or a broader range of frequencies. In the context of this question, the correct answer is bandwidth.

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117. Signals generated at frequencies above and below a carrier frequency by an amount equal to the modulating frequency are called

Explanation

Sidebands are signals that are generated at frequencies above and below a carrier frequency by an amount equal to the modulating frequency. These sidebands contain the information that is being transmitted and are essential for the modulation and demodulation process in communication systems. Duplex signals refer to the simultaneous transmission of signals in both directions, analog signals are continuous and vary smoothly over time, and gamma rays are a form of electromagnetic radiation.

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118. The commercial name for a PAN network technology similar to Bluetooth that is a short-range technology with networking capability is

Explanation

ZigBee is the correct answer because it is a commercial name for a PAN (Personal Area Network) technology that is similar to Bluetooth. ZigBee is known for its short-range capabilities and networking capability, making it suitable for applications such as home automation, industrial control, and sensor networks. It operates on low power and is designed for low data rate applications, making it ideal for devices that require long battery life.

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119. The first digital code was the:

Explanation

The Morse code is considered to be the first digital code because it was developed in the early 1830s by Samuel Morse and Alfred Vail as a way to encode messages to be transmitted over telegraph lines. It uses a series of dots and dashes to represent letters and numbers, allowing for the transmission of information using a binary system. The ASCII code, Baudot code, and C code are all digital codes as well, but they were developed after Morse code.

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120. What function is performed by a Fast Fourier Transform?

Explanation

A Fast Fourier Transform (FFT) is a mathematical algorithm used to convert digital signals from the time domain to the frequency domain. It analyzes the input signal and breaks it down into its individual frequency components, allowing for analysis and manipulation of the signal's frequency content. This process is commonly used in fields such as signal processing, audio analysis, and image processing.

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121. What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus or minus 7.5 kHz when the maximum modulation frequency is 3.5 kHz?

Explanation

The deviation ratio of an FM-phone signal is calculated by dividing the maximum frequency swing by the maximum modulation frequency. In this case, the maximum frequency swing is plus or minus 7.5 kHz, and the maximum modulation frequency is 3.5 kHz. Therefore, the deviation ratio is 7.5 kHz / 3.5 kHz = 2.14.

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122. What is deviation ratio?

Explanation

Deviation ratio refers to the ratio of the maximum carrier frequency deviation to the highest audio modulating frequency. This means that it measures the extent to which the carrier frequency deviates from its original frequency due to the audio signal. A higher deviation ratio indicates a larger change in the carrier frequency, resulting in a more pronounced modulation effect.

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123. On networks, long messages are divided into "chunks" called:

Explanation

On networks, long messages are divided into "chunks" called packets. This is done to efficiently transmit data over the network. Each packet contains a portion of the message along with header information that helps in routing and reassembling the message at the destination. By dividing the message into smaller packets, it becomes easier to handle and transmit them across the network, ensuring reliable and efficient communication. Nodes, carriers, and tokens are not the correct terms for dividing long messages on networks.

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124. What does the space weather term G5 mean?

Explanation

G5 refers to an extreme geomagnetic storm. Geomagnetic storms are disturbances in Earth's magnetosphere caused by solar wind activity. G5 is the highest level on the geomagnetic storm scale, indicating a severe storm that can have significant impacts on power grids, satellite systems, and other technological infrastructure. This level of storm can also lead to beautiful auroras and disruptions in radio communications.

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125. The process of phase-modulating a carrier with binary data is called

Explanation

Phase-shift keying (PSK) is the correct answer because it refers to the process of phase-modulating a carrier with binary data. In PSK, the phase of the carrier signal is shifted to represent different binary symbols. Each phase shift corresponds to a different symbol, allowing for the transmission of digital data over a carrier signal. This modulation technique is commonly used in telecommunications and digital communication systems.

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126. How can linearly polarized Yagi antennas be used to produce circular polarization?

Explanation

By arranging two Yagis perpendicular to each other with the driven elements at the same point on the boom and feeding them 90 degrees out of phase, the electromagnetic waves emitted by each Yagi will combine to produce circular polarization. The phase difference between the two Yagis causes the electric field of the resulting wave to rotate, creating circular polarization. This configuration is known as a crossed Yagi array and is commonly used to produce circularly polarized radiation.

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127. An intranet connected to the Internet is often protected by:

Explanation

An intranet connected to the Internet is often protected by a "firewall". A firewall is a security measure that acts as a barrier between the internal network (intranet) and the external network (Internet). It monitors and controls incoming and outgoing network traffic, allowing only authorized and safe connections while blocking unauthorized access or potentially harmful data. This helps to prevent unauthorized access, data breaches, and other security threats, ensuring the safety and integrity of the intranet.

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128. Mathematically, the calculation of FM bandwidth requires the use of:

Explanation

Bessel functions are used in the calculation of FM (frequency modulation) bandwidth. These functions are mathematical functions that are particularly useful in solving problems involving wave propagation and oscillations. In the context of FM bandwidth calculation, Bessel functions help in determining the spectral characteristics of the modulated signal. By using Bessel functions, one can accurately calculate the bandwidth of an FM signal, which is important for various applications in telecommunications and signal processing.

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129. What is the best time of day for transequatorial propagation?

Explanation

The best time of day for transequatorial propagation is in the afternoon or early evening. This is because during this time, the ionosphere is at its most active state, allowing radio waves to travel further distances. In the afternoon and early evening, the sun's rays are at an angle that maximizes the ionization of the ionosphere, creating favorable conditions for long-distance radio communication.

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130. Which of these is not a pulse-modulation technique:

Explanation

PPS is not a pulse-modulation technique. PDM stands for Pulse-Density Modulation, PWM stands for Pulse-Width Modulation, and PPM stands for Pulse-Position Modulation. These are all techniques used to encode information in the form of pulses. However, PPS does not stand for any commonly known pulse-modulation technique.

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131. What type cable consists of a thin center conductor surrounded by an insulating material that is completely encircled by a shield?

Explanation

A coaxial cable consists of a thin center conductor surrounded by an insulating material that is completely encircled by a shield. This shield helps to prevent interference and signal loss by providing a barrier between the center conductor and external electromagnetic fields. The coaxial design also allows for the transmission of high-frequency signals with low attenuation, making it suitable for applications such as cable television, internet, and telecommunications.

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132. At what frequency does home microwave oven is operating?

Explanation

A home microwave oven operates at a frequency of 2.45 GHz. This frequency is in the gigahertz range, which is equivalent to 2.45 billion cycles per second. Microwave ovens use this frequency because it allows for efficient heating of food through the absorption of microwave energy by water molecules. The 2.45 GHz frequency is also commonly used in other applications, such as Wi-Fi and Bluetooth devices.

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133. How frequently must an analog signal be sampled by an analog-to-digital converter so that the signal can be accurately reproduced?

Explanation

To accurately reproduce an analog signal using an analog-to-digital converter, the signal must be sampled at a rate that is at least twice the rate of the highest frequency component of the signal. This is known as the Nyquist-Shannon sampling theorem. By sampling at this rate, it ensures that the original analog signal can be accurately reconstructed from the digital samples without any loss of information. Sampling at a rate lower than this would result in aliasing, where high-frequency components of the signal would be incorrectly represented in the digital form.

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134. The ideal standing wave ratio is

Explanation

The ideal standing wave ratio is 1:1 because it represents a perfect match between the input and output impedance of a transmission line. This means that all of the power is being efficiently transferred from the source to the load without any reflections or loss. A 1:1 standing wave ratio indicates maximum power transfer and is considered the most desirable condition in a transmission line system.

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135. FTP is used to:

Explanation

FTP (File Transfer Protocol) is a standard network protocol used to transfer files between a server on the network and a user. It provides a simple and efficient way to upload, download, and manage files over a network. FTP allows users to authenticate themselves with a username and password, and then navigate through directories on the server to access and transfer files. It is commonly used in web development, file sharing, and remote server administration.

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136.  In free space, radio signals travel at approximately ____________________ meters per second.

Explanation

Radio signals travel at approximately 300 million meters per second in free space. This is the speed of light in a vacuum, which is the maximum speed at which electromagnetic waves can travel.

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137. The number of layers in ISO OSI is:

Explanation

The correct answer is 7 because the ISO OSI (Open Systems Interconnection) model consists of seven layers. These layers include the physical layer, data link layer, network layer, transport layer, session layer, presentation layer, and application layer. Each layer has specific functions and responsibilities in the communication process, allowing for standardized and efficient communication between different network devices and systems.

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138. VSWR stands for

Explanation

VSWR stands for Voltage Standing Wave Ratio. It is a measure of how well a load is matched to a transmission line. VSWR is used to determine the amount of power that is reflected back from the load to the source. A high VSWR indicates a mismatch between the load and the transmission line, which can result in power loss and signal distortion. Therefore, the correct answer is "voltage SWR".

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139. A "repeater" is used to:

Explanation

A "repeater" is a device used to extend the range of a radio communications system. It receives a weak signal and retransmits it at a higher power, allowing the signal to travel further distances. By amplifying and retransmitting the signal, repeaters help overcome the limitations of signal degradation and improve the overall coverage area of the radio system.

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140. What are the two families of circles and arcs that make up a Smith chart?

Explanation

The Smith chart is a graphical tool used in RF and microwave engineering to analyze and design circuits. It consists of two families of circles and arcs that represent the combination of resistance and reactance. These families of circles and arcs are used to plot and analyze impedance values, making it easier to understand and manipulate complex impedance values in the design and analysis of RF circuits.

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141. What is transequatorial propagation?

Explanation

Transequatorial propagation refers to the propagation of signals between two mid-latitude points that are located at approximately the same distance north and south of the magnetic equator. This means that the signals are able to travel across the equator and reach points on the opposite side. It is important to note that this type of propagation occurs between mid-latitude points, not necessarily at the same latitude.

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142. What is the result of skin effect?

Explanation

The skin effect refers to the phenomenon where RF current tends to flow more towards the outer surface of a conductor as the frequency increases. This is because at higher frequencies, the inductance of the conductor causes the current to concentrate in a thinner layer closer to the surface. This effect is due to the opposing magnetic fields generated by the current, which repel it towards the outer regions of the conductor. As a result, the effective resistance of the conductor increases, leading to higher impedance.

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143. Basic ISDN has not been widely adopted because:

Explanation

Basic ISDN has not been widely adopted because it took too long to develop, it is too slow, and it has been surpassed by newer technologies. These factors combined have led to its limited adoption.

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144. What is a use for a Wilkinson divider?

Explanation

A Wilkinson divider is a type of power divider that is used to split power equally between two 50-ohm loads while also maintaining a 50-ohm input impedance. This is important in order to prevent any reflections or mismatched impedance that could cause signal loss or distortion. By dividing the power evenly and maintaining the correct impedance, the Wilkinson divider ensures that both loads receive the same amount of power without any impedance mismatch issues.

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145. What parameter evaluates distortion of an AFSK signal caused by excessive input audio levels?

Explanation

Intermodulation Distortion (IMD) is the parameter that evaluates the distortion of an AFSK (Audio Frequency-Shift Keying) signal caused by excessive input audio levels. IMD occurs when multiple frequencies are present in the signal and interact with each other, resulting in distortion and interference. This can happen when the input audio levels are too high, causing non-linearities in the system. By measuring IMD, one can assess the level of distortion and ensure the signal quality is within acceptable limits.

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146. Which of the following are electromagnetic?

Explanation

All of the choices - radio waves, light, and gamma waves - are examples of electromagnetic waves. Electromagnetic waves are a form of energy that can travel through space and are characterized by their wavelength and frequency. Radio waves, light, and gamma waves all have different wavelengths and frequencies, but they all fall within the electromagnetic spectrum. Therefore, all of the given choices are electromagnetic in nature.

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147. With mixing:

Explanation

The correct answer is that the carrier frequency can be changed to any required value. This means that by using mixing, the carrier frequency can be adjusted to a specific frequency that is needed for a particular application or transmission. Mixing involves combining two or more signals, and by manipulating the input signals, the carrier frequency can be modified to meet the desired requirements. This flexibility in changing the carrier frequency makes mixing a versatile technique in various communication systems.

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148. A bridge:

Explanation

Bridges are networking devices that separate a network into "collision domains" by dividing the network into smaller segments. They also look at the address of each packet to determine where to forward it, operating at the data-link level. Therefore, the correct answer is that all of the choices mentioned are true for bridges.

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149. Overmodulation causes:

Explanation

Overmodulation refers to the process of increasing the amplitude of a signal beyond its normal limits. This can lead to distortion in the signal, where the waveform becomes altered and does not accurately represent the original signal. Additionally, overmodulation can also result in splatter, which refers to the spread of signal energy into adjacent frequency bands, causing interference with other signals. Therefore, both distortion and splatter are caused by overmodulation.

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150. How can intermodulation interference between two repeaters occur?

Explanation

Intermodulation interference between two repeaters can occur when they are in close proximity and the signals mix in the final amplifier of one or both transmitters. This mixing of signals can result in unwanted frequencies being generated, causing interference and degradation of the overall signal quality.

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151. Which of the following agency establishes and maintains electrical, electronic, and computing standards?

Explanation

IEEE, which stands for the Institute of Electrical and Electronics Engineers, is the agency that establishes and maintains electrical, electronic, and computing standards. They are responsible for developing and promoting standards in various fields, including technology, telecommunications, and computer science. IEEE's standards ensure interoperability, safety, and reliability in electrical and electronic devices and systems.

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152. What is the primary characteristic of chordal hop propagation?

Explanation

Chordal hop propagation refers to the phenomenon where radio signals are refracted multiple times by the ionosphere without any reflection from the ground. This means that the signals travel in a curved path between the transmitting and receiving stations, following the curvature of the Earth. This characteristic allows for long-distance communication over the horizon without the need for intermediate relay stations or reflections from the ground.

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153. The standard reference antenna for the directive gain is the

Explanation

The correct answer is isotropic antenna. The isotropic antenna is a theoretical antenna that radiates energy equally in all directions. It is used as a reference antenna to compare the gain of other antennas. The gain of an antenna is a measure of its ability to direct the radiated energy in a specific direction. By comparing the gain of an antenna to that of an isotropic antenna, we can determine how well the antenna is able to focus its energy in a particular direction.

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154. How can the output voltage of a multiple-turn receiving loop antenna be increased?

Explanation

To increase the output voltage of a multiple-turn receiving loop antenna, one can increase the number of turns and/or the area. This is because increasing the number of turns increases the overall magnetic flux passing through the loop, which in turn increases the induced voltage. Similarly, increasing the area of the loop also increases the amount of magnetic flux passing through it, leading to a higher induced voltage. Therefore, by either increasing the number of turns or the area, or both, the output voltage of the antenna can be increased.

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155. MAN stands for:

Explanation

MAN stands for Metropolitan-Area Network. A Metropolitan-Area Network is a computer network that spans a metropolitan area or a city. It is larger than a Local Area Network (LAN) but smaller than a Wide Area Network (WAN). MANs are typically used to connect multiple LANs within a city or metropolitan area, allowing for the sharing of resources and communication between different locations. This makes the option "Metropolitan-Area Network" the correct answer.

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156. The frequency band used for AM Broadcast is: 

Explanation

The frequency band used for AM Broadcast is 535 - 1605 KHz. This frequency range is commonly known as the Medium Wave band and is used for broadcasting AM (Amplitude Modulation) signals. AM radio signals have a longer wavelength compared to FM (Frequency Modulation) signals, allowing them to travel longer distances and penetrate obstacles like buildings and hills. This frequency band is widely used for commercial and public radio broadcasting.

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157. TCP stands for:

Explanation

TCP stands for Transmission Control Protocol. It is a fundamental protocol in the Internet protocol suite that provides reliable, ordered, and error-checked delivery of data packets over a network. TCP ensures that data sent over the network arrives at its destination without errors and in the correct order. It is widely used in applications that require reliable and secure data transmission, such as web browsing, email, file transfer, and streaming. TCP operates at the transport layer of the TCP/IP model and works in conjunction with the Internet Protocol (IP) to establish and maintain connections between devices on the network.

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158. What do the letters FEC mean as they relate to digital operation?

Explanation

Forward Error Correction (FEC) is a technique used in digital communication to detect and correct errors that occur during transmission. It involves adding redundant information to the transmitted data, which allows the receiver to identify and correct any errors without the need for retransmission. This method is particularly useful in situations where retransmission is not feasible or time-sensitive, such as in real-time video streaming or satellite communication.

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159. Both Impatt and Trapatt devices use avalanche effect.

Explanation

Both Impatt and Trapatt devices use the avalanche effect. The avalanche effect is a phenomenon where carriers in a semiconductor gain enough energy to cause additional carriers to be generated, resulting in a rapid increase in current. Both Impatt and Trapatt devices use this effect to generate high-frequency oscillations. Impatt devices use the avalanche breakdown in reverse biased p-n junctions, while Trapatt devices use the transit-time effect in reverse biased p-n junctions. Therefore, the statement that both Impatt and Trapatt devices use the avalanche effect is true.

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160. "IF" stands for:

Explanation

"IF" stands for intermediate frequency. This term is commonly used in electronics and telecommunications to refer to a frequency that is generated within a device or system as an intermediate step in the signal processing chain. The intermediate frequency is typically used to simplify the subsequent stages of signal amplification, filtering, and modulation/demodulation. It allows for easier signal processing and reduces the complexity of the overall system.

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161. Which of the following is a typical LAN configuration?

Explanation

A typical LAN configuration is client-server, where multiple client devices are connected to a central server. In this setup, the server provides resources and services to the clients, such as file sharing, printing, or internet access. The clients send requests to the server, and the server responds by providing the requested data or performing the requested tasks. This configuration allows for centralized management and control, making it efficient for organizations to share resources and collaborate within a local network.

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162. The time it takes a signal applied at one end of a transmission line to appear at the other end of the line is called

Explanation

Transit time refers to the duration it takes for a signal to travel from one end of a transmission line to the other end. It is the time required for the signal to propagate through the transmission medium and reach its destination. This term is commonly used in telecommunications and networking to measure the delay or latency in signal transmission.

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163. At what time of year is sporadic E propagation most likely to occur?

Explanation

Sporadic E propagation is most likely to occur around the solstices, especially the summer solstice. During this time, the ionosphere is more active and there are higher chances of sporadic E layers forming, which can enhance radio wave propagation. The summer solstice, being the longest day of the year, provides more time for these ionospheric conditions to develop, making it the most favorable time for sporadic E propagation.

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164. The modulation index can be derived from:

Explanation

The modulation index can be derived from both the time-domain and frequency-domain signals. The time-domain signal provides information about the amplitude variations of the carrier signal, while the frequency-domain signal provides information about the spectral distribution of the modulated signal. By analyzing both signals, the modulation index can be determined, which represents the extent of modulation applied to the carrier signal. This information is crucial in understanding the characteristics and performance of the modulation scheme used.

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165. Another name for an FM demodulator is

Explanation

An FM demodulator is also known as a discriminator because it is responsible for extracting the original audio signal from the frequency-modulated carrier wave. The discriminator detects and measures the variations in frequency of the carrier wave, which correspond to the variations in the audio signal. This process allows the demodulator to recover the original audio signal for playback or further processing. Therefore, the correct answer is discriminator.

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166. TRF stands for:

Explanation

TRF stands for Tuned Radio Frequency. This term refers to a type of radio receiver circuit that uses a series of tuned circuits to select and amplify specific radio frequencies. The tuned circuits are designed to resonate at specific frequencies, allowing only those frequencies to pass through and be amplified. This type of receiver was commonly used in early radio technology and is still used in some applications today.

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167. Which of the following descriptors indicates the greatest solar flare intensity?

Explanation

The letter "X" indicates the highest solar flare intensity. The classes are ranked in alphabetical order, with Class X being the highest. Therefore, Class X represents the greatest solar flare intensity.

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168. The optimum value for SWR is

Explanation

The optimum value for SWR is "one" because SWR, or Standing Wave Ratio, is a measure of how efficiently power is transmitted from a source to a load. An SWR of one indicates that the load impedance matches the source impedance perfectly, resulting in maximum power transfer and minimal reflection. This is the ideal condition for efficient power transmission and is considered the optimum value for SWR.

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169. UART stands for:

Explanation

UART stands for Universal Asynchronous Receiver-Transmitter. This is a communication protocol commonly used for serial communication between two devices. The term "universal" indicates that it can be used with a wide range of devices and applications. "Asynchronous" means that data is transmitted without the use of a clock signal, allowing for flexibility in timing. The term "receiver-transmitter" indicates that it can both receive and transmit data. Overall, UART is a widely used protocol for serial communication in various electronic devices.

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170.  For satellite communications, ____________________ noise can be a serious problem.

Explanation

For satellite communications, solar noise can be a serious problem. This is because solar noise refers to the interference caused by solar radiation, particularly in the form of electromagnetic waves emitted by the Sun. These waves can disrupt satellite signals and degrade the quality of communication. Therefore, satellite operators and engineers need to take into account solar noise when designing and operating satellite systems to ensure reliable and efficient communication.

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171. BISYNC:

Explanation

BISYNC is an IBM product that is a character-oriented protocol and requires the use of DLE. This means that all of the given choices are correct.

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172. Hollow metal conducting pipes designed to carry and constrain the electromagnetic waves of a microwave signal are:

Explanation

Waveguides are hollow metal conducting pipes that are specifically designed to carry and constrain the electromagnetic waves of a microwave signal. They are used to guide and direct the waves, preventing them from spreading out and ensuring efficient transmission. Waveguides are commonly used in microwave communication systems and devices such as antennas, radars, and satellite dishes. They are not the same as wavetraps, traveling wave tubes, or microwave tubes, which serve different purposes in the context of electromagnetic wave transmission.

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173. SDLC stands for:

Explanation

SDLC stands for Synchronous Data Link Control. This term refers to a communication protocol used in computer networks to synchronize the transmission of data between devices. It ensures reliable and error-free data transmission by using a combination of techniques such as error checking, flow control, and data framing. SDLC is commonly used in serial communication systems and is an essential component of the data link layer in the OSI model.

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174. Which of these feed line impedances would be suitable for constructing a quarter-wave Q-section for matching a 100-ohm loop to 50-ohm feed line?

Explanation

A quarter-wave Q-section is used to match the impedance of a transmission line to the impedance of a load. In this case, the load impedance is 100 ohms and the feed line impedance is 50 ohms. To achieve a proper match, the feed line impedance should be the geometric mean of the load impedance and the characteristic impedance of the transmission line. The geometric mean of 100 ohms and 50 ohms is 70.7 ohms, which is closest to 75 ohms. Therefore, a feed line impedance of 75 ohms would be suitable for constructing a quarter-wave Q-section in this scenario.

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175. ISP stands for:

Explanation

ISP stands for Internet Service Provider. An ISP is a company or organization that provides access to the internet for individuals and other organizations. They offer various services such as internet connectivity, email services, web hosting, and more. ISPs connect users to the internet through different technologies like dial-up, DSL, cable, or fiber optic connections. They play a crucial role in enabling individuals and businesses to access and utilize the internet for communication, information sharing, and other online activities.

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176. Approximately how long is each side of a quad antenna driven element?

Explanation

The length of each side of a quad antenna driven element is approximately 1/4 wavelength. This is because a quad antenna is a type of loop antenna, and for optimal performance, the length of each side should be a quarter of the wavelength of the desired frequency. This allows for efficient transmission and reception of electromagnetic waves.

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177. SLIC stands for:

Explanation

SLIC stands for subscriber line interface card. This card is used in telecommunications systems to connect subscriber lines to the central office equipment. It provides the interface between the subscriber's equipment and the telecommunications network. The SLIC card converts analog signals from the subscriber line into digital signals that can be processed by the central office equipment. It also performs functions such as line testing, line isolation, and line supervision.

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178. A cordless telephone is a

Explanation

A cordless telephone is a full duplex, two-way radio made up of a handset and base unit. Full duplex means that both parties can speak and listen simultaneously, allowing for a more natural conversation. The handset and base unit work together to transmit and receive signals, enabling communication between the two parties.

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179. UTP stands for:

Explanation

UTP stands for Unshielded Twisted-Pair copper wire. This is a type of cable used for networking that consists of multiple pairs of insulated copper wires twisted together. The term "unshielded" means that the cable does not have any additional shielding or protection, while "twisted-pair" refers to the way the wires are twisted together to reduce interference and crosstalk. UTP cables are commonly used for Ethernet connections and are cost-effective and easy to install.

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180. In a communications system, noise is most likely to affect the signal

Explanation

In a communications system, noise is most likely to affect the signal in the channel. This is because the channel is the medium through which the signal travels from the transmitter to the destination. During transmission, various factors such as interference, distortion, and attenuation can introduce noise into the signal. The channel acts as a pathway for the signal, and any disturbances or imperfections in the channel can disrupt the signal and introduce noise. Therefore, the channel is the most susceptible to noise in a communications system.

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181. What is the term for spurious signals generated by the combination of two or more signals in a non-linear device or circuit?

Explanation

Intermodulation refers to the phenomenon where two or more signals combine in a non-linear device or circuit, resulting in the generation of spurious signals. These spurious signals can interfere with the desired signals and cause distortion or degradation of the overall signal quality. Amplifier desensitization is the reduction in sensitivity of an amplifier due to the presence of strong signals. Neutralization is a technique used to cancel out unwanted signals or interference. Adjacent channel interference occurs when signals from neighboring channels interfere with each other.

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182. A hub:

Explanation

A hub is a networking device that operates at the physical layer of the OSI model. It receives incoming packets from one port and broadcasts them to all other ports connected to it. This means that any packet received by the hub will be sent out to all terminals connected to it, regardless of the intended recipient. Hubs are often used in small networks or as a simple means of connecting devices, but they are not commonly used in Ethernet-type networks where switches are preferred for their ability to send packets only to the intended recipient.

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183. The five-level teletype code was invented by:

Explanation

Emile Baudot is the correct answer because he is credited with inventing the five-level teletype code. The five-level teletype code, also known as the Baudot code, was a telegraph code used for transmitting text messages over telegraph lines. Baudot's invention revolutionized telecommunication by allowing for faster and more efficient transmission of messages. His code was widely adopted and became the basis for many subsequent telegraph codes.

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184. What agency is responsible for allocating bands of frequencies and for setting limitations on broadcast power for different types of radio and TV operations?

Explanation

The Federal Communications Commission (FCC) is responsible for allocating bands of frequencies and setting limitations on broadcast power for different types of radio and TV operations. The FCC is an independent agency of the United States government that regulates interstate communications by radio, television, wire, satellite, and cable. They ensure that the use of frequencies is properly managed and that broadcasters adhere to power limitations to prevent interference and promote efficient use of the radio spectrum. OSHA, IEEE, and ANSI are not responsible for these specific tasks.

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185. For best matching, the load on a cable should be

Explanation

The load on a cable should be equal to Z0. Z0 represents the characteristic impedance of the cable, which is the impedance at which the cable is designed to operate efficiently. Matching the load impedance to Z0 ensures that there is minimal reflection of the signal and maximum power transfer along the cable. Therefore, having the load equal to Z0 is the ideal condition for best matching.

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186. What is the effective radiated power relative to a dipole of a repeater station with 200 watts transmitter power output, 4 dB feed line loss, 3.2 dB duplexer loss, 0.8 dB circulator loss, and 10 dBd antenna gain?

Explanation

The effective radiated power (ERP) is a measure of the power that a transmitting antenna radiates in a particular direction. It takes into account the transmitter power output, feed line loss, duplexer loss, circulator loss, and antenna gain. In this case, the transmitter power output is 200 watts, the feed line loss is 4 dB, the duplexer loss is 3.2 dB, the circulator loss is 0.8 dB, and the antenna gain is 10 dBd. By subtracting the losses from the transmitter power output and adding the antenna gain, we can calculate the ERP. The correct answer is 317 watts, which represents the effective radiated power relative to a dipole.

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187. A receiver that responds to a desired signal, but not to another signal very close by in frequency, has good

Explanation

A receiver that responds to a desired signal, but not to another signal very close by in frequency, has good selectivity. This means that the receiver is able to filter out unwanted signals and only respond to the specific signal it is intended to receive. Selectivity is an important characteristic of a receiver as it allows for better signal discrimination and improves the overall performance and accuracy of the receiver.

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188. Which of the following modes can be demodulated with an envelope detector?

Explanation

An envelope detector is a simple circuit that can demodulate amplitude modulation (AM) signals. It works by extracting the envelope (the varying amplitude) of the modulated signal. The other modes listed in the question, such as CW (continuous wave), FSK (frequency-shift keying), and USB (upper sideband), do not involve amplitude modulation and therefore cannot be demodulated using an envelope detector.

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189. HTTP allows the use of:

Explanation

HTTP (Hypertext Transfer Protocol) is a protocol used for transmitting data over the internet. It allows the use of browsers to access and view web pages. Browsers are software applications that interpret and display HTML files, allowing users to navigate the internet and access websites. Therefore, the correct answer is "browsers."

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190. What does the MDS of a receiver represent?

Explanation

The MDS of a receiver represents the minimum discernible signal. This refers to the smallest signal that can be detected and distinguished from noise by the receiver. It indicates the sensitivity of the receiver and its ability to detect weak signals.

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191. What would be the SWR if you feed a vertical antenna that has a 25-ohm feed-point impedance with 50-ohm coaxial cable?

Explanation

If a 25-ohm feed-point impedance antenna is fed with 50-ohm coaxial cable, the SWR (Standing Wave Ratio) would be 2:1. SWR is a measurement of how well the antenna impedance matches the impedance of the transmission line. In this case, the impedance mismatch between the antenna and the coaxial cable causes a reflection of the signal, resulting in a standing wave pattern along the transmission line. The 2:1 SWR indicates that there is a partial reflection of the signal, with some power being reflected back towards the source.

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192. A mobile operating system (OS) based on the Linux kernel and currently developed by Google.

Explanation

Android is a mobile operating system developed by Google that is based on the Linux kernel. It is the correct answer because it is the only option mentioned that fits the description provided. Symbian, iOS, and MeeGo are all different operating systems, but they are not based on the Linux kernel and are not currently developed by Google.

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193. As a cell-phone user passes from one cell to another:

Explanation

As a cell-phone user passes from one cell to another, a "handoff" process occurs. This process involves the transfer of the ongoing call from one cell to another, ensuring that the call remains uninterrupted and the user experiences seamless connectivity. This is necessary because cells have a limited coverage area, and as the user moves away from one cell's coverage area, the signal strength decreases. The handoff process allows the call to be transferred to a neighboring cell with better signal strength, ensuring continuous communication for the user.

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194. Which of the following techniques is normally used by low Earth orbiting digital satellites to relay messages around the world?

Explanation

Low Earth orbiting digital satellites typically use the store-and-forward technique to relay messages around the world. This technique involves the satellite receiving a message, storing it onboard, and then forwarding it to the intended recipient when it comes within range. This allows for efficient communication as the satellite can collect and store multiple messages before relaying them, even if the sender and receiver are not in direct line of sight.

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195. Basic FDM groups can be combined into:

Explanation

Basic FDM groups can be combined into supergroups, mastergroups, and jumbogroups. This means that it is possible to merge multiple basic FDM groups to form any of these three types of groups.

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196. What is an advantage of having a variety of receiver IF bandwidths from which to select?

Explanation

Having a variety of receiver IF bandwidths allows the receive bandwidth to be adjusted to match the modulation bandwidth. This is advantageous because it maximizes the signal-to-noise ratio and minimizes interference. By matching the receive bandwidth to the modulation bandwidth, the receiver can effectively capture the desired signal while rejecting unwanted noise and interference. This improves the overall performance and quality of the received signal.

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197. An Area Network that would extend typically across a city.

Explanation

A Metropolitan Area Network (MAN) is a type of network that covers a larger geographical area than a local area network (LAN) but smaller than a wide area network (WAN). It typically extends across a city or metropolitan area. Therefore, the correct answer is Metropolitan.

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198. What is an effect of excessive phase noise in a receiver's local oscillator?

Explanation

Excessive phase noise in a receiver's local oscillator can combine with strong signals on nearby frequencies to generate interference. This interference can disrupt the receiver's ability to accurately receive and interpret signals, leading to degraded performance.

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199. NIC stands for:

Explanation

NIC stands for Network Interface Card, which is a hardware component that allows a computer to connect to a network. It provides the physical connection between the computer and the network, enabling data transmission. The NIC is responsible for converting data into a format that can be transmitted over the network and vice versa. It is an essential component for network communication and is commonly used in both wired and wireless networks.

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200. Interference generated by lightning, motors, automotive ignition systems, and any power line switching that produces transient signals is referred to as

Explanation

Interference generated by lightning, motors, automotive ignition systems, and power line switching can create unwanted signals or disturbances in electronic devices. These disturbances are commonly referred to as "noise". Noise can disrupt the normal functioning of electronic systems, causing errors or malfunctions. It is important to minimize or eliminate noise in order to ensure proper operation of electronic equipment.

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AM stands for
VHF stands for the ____________________ frequency band.
The smallest element or part of a picture is a
What type of satellite appears to stay in one position in the sky?
QAM stands for:
SWR stands for
Which generation of cellular network technology preceded 5G?
FSK stands for:
What is the modulation index of an FM-phone signal having a maximum...
TDM stands for
HDTV stands for
 It allows many signals to share a channel.
What is antenna bandwidth?
IP stands for:
FDM stands for
A technique used by codes to convert an analog signal into a digital...
Thermal noise is caused by the random motions of ____________________...
HTTP stands for:
All cell phone systems are
What are the principal frequencies that appear at the output of a...
What is the name of the Philippines first microsatellite?
What is the name of the Philippines second microsatellite?
A radio signal's ____________________ is the distance it travels...
The brain of any computer system is
PSK stands for:
Which of the following features is not currently available with...
Which of the following is often determined using a Smith chart?
When two or more signals share a common channel, it is called
A balanced load can be connected to an unbalanced cable
How does the spread spectrum technique of frequency hopping work?
A mobile operating system developed by Apple Inc. and distributed...
What is the radiation resistance of an antenna?
What is a folded dipole antenna?
Which of the following modes is used to send image data over telephone...
Unwanted ads and solicitations via email fall into the category of
EIRP stands for:
Codec stands for:
NBFM stands for:
What is the modulation index of an FM-phone signal having a maximum...
A complete communication system must include
Radio broadcasting is a familiar example of
Which of the following is a disadvantage of 5G?
CRC stands for:
What must be done to prevent standing waves on an antenna feed line?
What is microstrip?
DSP stands for:
DSL stands for:
ITU is an abbreviation for:
The 'B' in Hartley's Law stands for
"Signaling" is used to indicate:
The highest layer of the ionosphere is
Cellular radio systems divide the service area into many smaller areas...
The velocity factor of a transmission line depends on
Which of the following can be calculated using a Smith chart?
The frequency band of the FM Broadcast is: 
TDM stands for:
Broadband LANs:
TEM stands for:
What are the typical characteristic impedances of coaxial cables used...
ASCII stands for:
What current flows equally on all conductors of an unshielded...
What standing wave ratio will result from the connection of a 50-ohm...
A non-optimum value for SWR will cause
TDMA stands for:
Manchester coding:
What term describes station output, taking into account all gains and...
Orbital disturbances of a geosynchronous satellite are caused by the
The more information per second you send, the ____________________ the...
Most LANs:
In which mode of PM does the peak power level of the pulses vary?
Oscillators whose frequencies are controlled by an external input...
The SC in SSB SC stands for:
FTP stands for:
A circuit that converts an instantaneous value of analog voltage into...
Which of the following is a type of private telephone system?
Which of the following indicates the relative strengths of the signal...
The part, or parts, of a sinusoidal carrier that can be modulated are
Which of the following is a Yagi antenna design variable that could be...
What is the cause of auroral activity?
When a transmitter is connected to a resistor instead of an antenna,...
What is the advantage of including parity bits in ASCII characters?
Microwave resonators are used in:
Which of the following light sources cannot be used in fiber-optic...
An antenna made up of a driven element and one or more parasitic...
What is an isotropic antenna?
The lowest-level layer in ISO OSI is called the:
Public-key encryption:
To couple a coaxial line to a parallel-wire line, it is best to use a
Shot noise is generated in
Inmarsat stands for:
The original signal being transmitted from the earth station to the...
If an AM signal is modulated with audio having frequencies up to 5...
Which is a possible polarization for an electromagnetic wave?
What standing wave ratio will result from the connection of a 50-ohm...
Which of the following is a system of delivering the TV signal to home...
Why does the radio-path horizon distance exceed the geometric horizon?
The standard that describes Ethernet-type networks is:
A transponder is a satellite equipment which
What is the wireless technique that uses thin, inexpensive tags or...
Character codes include:
What is the velocity factor of a transmission line?
The path from earth to a satellite is called the
The two basic specifications for a receiver are:
Mathematically, a spectrum is represented by a
Frame Relay:
The first geostationary satellite launched in 1965 was called
It is an umbrella term for a number of standards organizations which...
How does ARQ accomplish error correction?
A frequency-selective circuit designed to pass some frequencies and...
Which type of atmospheric structure can create a path for microwave...
The job of the carrier is to get the information through the 
AGC stands for:
ADSL stands for:
What occurs when an excessive amount of signal energy reaches a mixer...
With AM which of the following conveys no information?
The difference between the upper and lower frequency limits of a...
Signals generated at frequencies above and below a carrier frequency...
The commercial name for a PAN network technology similar to Bluetooth...
The first digital code was the:
What function is performed by a Fast Fourier Transform?
What is the deviation ratio of an FM-phone signal having a maximum...
What is deviation ratio?
On networks, long messages are divided into "chunks" called:
What does the space weather term G5 mean?
The process of phase-modulating a carrier with binary data is called
How can linearly polarized Yagi antennas be used to produce circular...
An intranet connected to the Internet is often protected by:
Mathematically, the calculation of FM bandwidth requires the use of:
What is the best time of day for transequatorial propagation?
Which of these is not a pulse-modulation technique:
What type cable consists of a thin center conductor surrounded by an...
At what frequency does home microwave oven is operating?
How frequently must an analog signal be sampled by an...
The ideal standing wave ratio is
FTP is used to:
 In free space, radio signals travel at approximately...
The number of layers in ISO OSI is:
VSWR stands for
A "repeater" is used to:
What are the two families of circles and arcs that make up a Smith...
What is transequatorial propagation?
What is the result of skin effect?
Basic ISDN has not been widely adopted because:
What is a use for a Wilkinson divider?
What parameter evaluates distortion of an AFSK signal caused by...
Which of the following are electromagnetic?
With mixing:
A bridge:
Overmodulation causes:
How can intermodulation interference between two repeaters occur?
Which of the following agency establishes and maintains electrical,...
What is the primary characteristic of chordal hop propagation?
The standard reference antenna for the directive gain is the
How can the output voltage of a multiple-turn receiving loop antenna...
MAN stands for:
The frequency band used for AM Broadcast is: 
TCP stands for:
What do the letters FEC mean as they relate to digital operation?
Both Impatt and Trapatt devices use avalanche effect.
"IF" stands for:
Which of the following is a typical LAN configuration?
The time it takes a signal applied at one end of a transmission line...
At what time of year is sporadic E propagation most likely to occur?
The modulation index can be derived from:
Another name for an FM demodulator is
TRF stands for:
Which of the following descriptors indicates the greatest solar flare...
The optimum value for SWR is
UART stands for:
 For satellite communications, ____________________ noise can be...
BISYNC:
Hollow metal conducting pipes designed to carry and constrain the...
SDLC stands for:
Which of these feed line impedances would be suitable for constructing...
ISP stands for:
Approximately how long is each side of a quad antenna driven element?
SLIC stands for:
A cordless telephone is a
UTP stands for:
In a communications system, noise is most likely to affect the signal
What is the term for spurious signals generated by the combination of...
A hub:
The five-level teletype code was invented by:
What agency is responsible for allocating bands of frequencies and for...
For best matching, the load on a cable should be
What is the effective radiated power relative to a dipole of a...
A receiver that responds to a desired signal, but not to another...
Which of the following modes can be demodulated with an envelope...
HTTP allows the use of:
What does the MDS of a receiver represent?
What would be the SWR if you feed a vertical antenna that has a 25-ohm...
A mobile operating system (OS) based on the Linux kernel and currently...
As a cell-phone user passes from one cell to another:
Which of the following techniques is normally used by low Earth...
Basic FDM groups can be combined into:
What is an advantage of having a variety of receiver IF bandwidths...
An Area Network that would extend typically across a city.
What is an effect of excessive phase noise in a receiver's local...
NIC stands for:
Interference generated by lightning, motors, automotive ignition...
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