3D153 CDC, Volume 1. General Subjects

The correct answer is "Auto". In Auto mode, the oscilloscope continuously triggers and displays the waveform on the screen, regardless of whether there is an input signal or not. This mode is useful for monitoring the instrument's performance or checking for any noise or interference in the absence of an input signal.

In synchronous transmission, data is transmitted in blocks rather than individual characters. Therefore, if an error occurs, it is likely that an entire block of data will be lost, rather than just one character. This is because synchronous transmission relies on the synchronization of data between the sender and receiver, and if there is an error in one block, it can disrupt the synchronization and cause the loss of the entire block of data.

When you are reasonably sure electromagnetic interference (EMI) exists, the best course of action is to systematically gather data for analysis. This means collecting relevant information and data about the interference, such as its frequency, duration, and any patterns or trends. By doing so, you can better understand the nature of the interference and its potential impact on your system. This data will also be useful in troubleshooting and finding possible solutions to mitigate or eliminate the interference.

The two switches on the front panel of the wattmeter correspond to the power range of the forward element. This means that the switches are used to select the appropriate power range for measuring the forward power. The wattmeter is designed to measure power, and by adjusting the switches, the user can ensure that the wattmeter is accurately measuring the power within the desired range. The switches are not related to the frequency range or the reverse element of the wattmeter.

Voltage surges, arcing, and corona discharges can cause disturbances in power lines, resulting in man-made noise. This noise can be heard as crackling or buzzing sounds coming from the power lines. Relays, switching equipment, and lighting are not directly associated with voltage surges, arcing, or corona discharges, so they are not the correct answers for this question.

Adding more phase shifts allows for a higher number of distinct symbols to be represented, which increases the data rate that can be transmitted within a given bandwidth. This means that more information can be transmitted in a shorter amount of time, leading to higher data rates.

A digital storage oscilloscope normally uses real-time sampling on single-shot or seldom-occurring signals. Real-time sampling allows the oscilloscope to capture and display the waveform as it occurs in real-time, providing an accurate representation of the signal. This is particularly useful for capturing and analyzing transient or sporadic signals that may only occur once or infrequently. Sequential sampling, on the other hand, is used for signals that repeat regularly, while repetitive sampling is used for signals that repeat at a known interval. Random sampling is not typically used in this context.

The Institute of Electrical and Electronics Engineers (IEEE) recommends a ground resistance value of 5 ohms or less. This is because a lower ground resistance helps to ensure the safety and effectiveness of electrical systems. A lower resistance allows for better grounding, which helps to dissipate excess electrical energy and prevent electrical shocks or damage to equipment. Therefore, it is important to maintain a ground resistance value of 5 ohms or less to ensure the proper functioning of electrical systems.

In pulse code modulation (PCM), the first step is to band-limit the analog signal. Band-limiting ensures that the analog signal does not contain any frequencies beyond a certain range, which helps in reducing noise and distortion during the sampling process. By band-limiting the analog signal, it becomes easier to accurately sample and encode the signal into discrete amplitudes or binary code numbers. This step is crucial in ensuring the fidelity and accuracy of the digital representation of the analog signal in PCM.

The Joint Spectrum Center (JSC) is tasked with providing interference resolution support to the unified commanders. They are responsible for managing and coordinating the use of the electromagnetic spectrum by military forces. The JSC works to ensure that different military units can effectively communicate and operate without interference from other sources. They analyze and resolve any interference issues that may arise, allowing the unified commanders to carry out their missions without disruptions in communication.

Semiconductor laser diodes (LD) are applicable to fiber optic waveguides because they can generate coherent light with high intensity. This makes them suitable for long-distance communication through optical fibers. Light-emitting diodes (LED) can also be used, but they produce incoherent light with lower intensity. Hybrid photodiodes and integrated photodiode preamplifiers are not light sources, but rather detectors used to convert light signals into electrical signals. Therefore, the correct answer is semiconductor laser diodes (LD).

Surge arresters are used to protect electrical systems from voltage surges. They work by diverting the excess voltage to the ground. In order to ensure their proper functioning, surge arresters are always used in combination with linear filters. Linear filters are designed to remove noise and harmonics from the electrical signal, ensuring a clean and stable power supply. By using linear filters in conjunction with surge arresters, the electrical system is protected from both voltage surges and unwanted electrical disturbances.

When modulation is reduced to less than 100%, it means that the amplitude of the carrier signal is not fully modulated by the information signal. In this case, the carrier power remains unchanged because it is not being affected by the modulation. The reduction in modulation only affects the sideband power, which carries the information signal. Therefore, there is no reduction in carrier power.

ARQ is an error-correction technique that sends a retransmittal request by the receiver to the sender if it finds an error in a received frame. This technique allows for the detection and correction of errors in data transmission by requesting the sender to resend the frame that contains errors. By using ARQ, the receiver can ensure that the data is received correctly without errors.

In real-time sampling, linear interpolation is used when measuring pulse waves. Linear interpolation involves estimating values between two known values by drawing a straight line between them. This method is commonly used in digital signal processing to reconstruct continuous signals from discrete samples. In the context of measuring pulse waves, linear interpolation helps to accurately estimate the values of the waveform between the sampled points.

The radio frequency blanking output is used during the automatic zeroing operation on the HP 436A power meter. This output helps to eliminate any unwanted radio frequency signals that may interfere with the accuracy of the zeroing process. By blanking out these signals, the power meter can ensure that it is properly calibrated and ready for accurate power measurements.

A peaking aid is a feature that helps in making adjustments to optimize the parameters measured by a wattmeter. It assists in fine-tuning and maximizing the accuracy of the measurements by providing a visual or audio indication when the parameter being measured is at its peak or optimum value. This allows the user to make necessary adjustments to optimize the performance of the wattmeter and ensure accurate readings.

A device that accepts optical signals from an optical fiber and converts them into electrical signals is called a receiver. Receivers are an essential component in optical communication systems as they receive the optical signals and convert them into electrical signals that can be further processed and utilized.

Scintillation refers to the rapid fluctuations in the amplitude and phase of a radio signal caused by atmospheric disturbances. These disturbances, which are a result of initial nuclear radiation, affect communications by causing the signal to fluctuate and become unstable. This can lead to difficulties in receiving or transmitting messages accurately, resulting in a disruption or blackout of communication. Attenuation and absorption, on the other hand, refer to the weakening or loss of signal strength, but they are not specifically related to atmospheric disturbances from nuclear radiation.

The correct answer is Quick fix interference reduction capability. This is because the question is asking which air force service provides on-site direction finding and interference problem analysis. Quick fix interference reduction capability refers to a service that is able to quickly identify and reduce interference issues. Therefore, it is the most appropriate answer to the question.

A current probe does not need to make physical contact with the circuit under test because it uses magnetic induction to measure the current flowing through a conductor. It clamps around the conductor and detects the magnetic field generated by the current, allowing for non-invasive current measurement. This is different from other probes like active (FET) probes, passive dividers, and passive 1:1 probes, which require direct contact with the circuit to measure voltage or other electrical parameters.

The correct answer is Central Processing Unit (CPU). In a protocol analyzer, the CPU is responsible for processing the frames based on the selected test and user configuration inputs. It performs the necessary calculations and operations to analyze and interpret the data in the frames. The CPU processes the frames in real-time, allowing the protocol analyzer to capture and analyze network traffic efficiently. The CPU's processing power and speed greatly impact the performance and capabilities of the protocol analyzer.

In frequency modulation (FM), the amount of oscillator frequency change is directly proportional to the amplitude of the modulating signal. This means that as the amplitude of the modulating signal increases, the frequency of the carrier signal will also increase, and vice versa. This relationship allows for the encoding of information in the frequency variations of the carrier signal in FM communication systems.

A communication service monitor combines the operations of many test instruments into a single compact unit. It is a versatile device that can perform various functions such as measuring voltage, impedance, and frequency, as well as analyzing and monitoring communication signals. This makes it a convenient and efficient tool for technicians and engineers working in the field of telecommunications.

The plug-in elements of the wattmeter are selected based on the frequency and power to be measured. This means that the specific elements used in the wattmeter will depend on the frequency of the electrical signal and the power level that needs to be measured. Different frequencies and power levels may require different elements in order to accurately measure the wattage.

Sampled data points are stored in the memory of a digital storage oscilloscope as waveform points. This means that the oscilloscope stores the actual data points that make up the waveform being measured. These points can then be displayed on the screen or analyzed further. Other options like sequential records, record lengths, or record points are not accurate descriptions of how the data is stored in the oscilloscope's memory.

Trace Route is the active test selected to see the path that the packets are traveling and the time it takes for the packets to complete the trip. Trace Route works by sending a series of packets with increasing Time to Live (TTL) values, which causes each router along the path to send back an ICMP Time Exceeded message. By analyzing these messages, Trace Route can determine the route that the packets are taking and calculate the round-trip time for each hop. This information is useful for troubleshooting network connectivity issues and identifying network latency or congestion.

The 25-pin connectors on the BER set are designed to simplify the connection of test equipment to the modem under test. Additionally, they are meant to carry the necessary signaling and handshake signals for modem operations. This means that the connectors not only make it easier to connect the test equipment to the modem, but also facilitate the communication between the test equipment and the modem by carrying the required signals.

The correct answer is Frequency counters, universal counters, microwave counters, and reciprocal counters. These four classes of electronic counters cover a wide range of applications and functionalities. Frequency counters are used to measure the frequency of a signal, universal counters can measure various parameters such as frequency, period, time interval, etc., microwave counters are specifically designed for high-frequency measurements, and reciprocal counters are used to measure the reciprocal of a signal's frequency. Together, these four classes of counters provide a comprehensive set of tools for electronic measurements.

The protocol statistics test window in a protocol analyzer provides information about the network utilization and frame errors that are specific to a particular protocol. This window allows users to analyze and monitor the performance and behavior of the protocol being tested, helping to identify any issues or inefficiencies in its usage. The other options, such as MAC node statistics, connection statistics, and node discovery, do not specifically focus on providing information about network utilization and frame errors related to a specific protocol.

The correct answer is Media access control (MAC) node statistics. This is because the MAC layer is responsible for the physical transmission of data packets, and the MAC node statistics window in a protocol analyzer would report errors that occur at this layer, such as bad frame check sequence (FCS), short frames, and jabbers.

An analog multimeter is not part of the communication service monitor because it is used for measuring electrical quantities such as voltage, current, and resistance, rather than specifically monitoring and analyzing communication signals. The other options - radio frequency generator, oscilloscope, and receiver - are all essential components of a communication service monitor as they are used for generating signals, visualizing waveforms, and receiving and decoding communication signals respectively.

The Subscriber (SC) fiber optic connector uses a push-pull engagement for mating. This means that the connector can be easily inserted and removed by pushing and pulling it, making it convenient and user-friendly. The other options, such as Biconic, Field (FC), and Sub-Miniature, Type A (SMA), do not use a push-pull engagement for mating.

When the modulating signal and carrier signal are combined within a modulator, the output signal contains a modulating signal, upper sideband (USB), and lower sideband (LSB). The modulating signal is the original signal that carries the information to be transmitted. The carrier signal is a high-frequency signal that is modulated by the modulating signal. The upper sideband (USB) is the portion of the modulated signal above the carrier frequency, while the lower sideband (LSB) is the portion below the carrier frequency. Therefore, the correct answer is modulating signal, upper sideband (USB), lower sideband (LSB).

A spectrum analyzer is an instrument used to measure the amplitude of different frequencies in a signal. It is used to analyze the frequency components of a waveform. Frequency stability refers to the ability of a signal to maintain a consistent frequency over time, which can be measured using other instruments like a frequency counter. Amplitude modulation is a technique used to vary the amplitude of a carrier signal according to the information being transmitted, and it can be measured using a spectrum analyzer. Subcarrier oscillator is a component used in certain modulation schemes, and its frequency can also be measured using a spectrum analyzer. Therefore, the measurement that is not made with a spectrum analyzer is peak-peak voltage.

The correct answer is "48-bit transmitter only." This means that the pattern simulator section of the BER test set accepts a 48-bit parallel word and generates a serial pattern. The other options mentioned, such as the PRN generator, PRN comparator, and 48-bit register with an 8-bit word display, do not fit the requirement of generating a serial pattern from a 48-bit parallel word.

The pattern simulator section of the BER test set converts the non-return zero-level (NRZ-L) data into the desired coding, such as non-return zero-mark (NRZ-M). This is done by the code converter, which transforms the data from one coding scheme to another. It takes the NRZ-L data and converts it into NRZ-M coding, which is the desired coding for the test. The code converter plays a crucial role in ensuring that the data is properly encoded for accurate testing and analysis.

The vertical redundancy check and longitudinal redundancy check are the two error detection methods that, when used together, are 98 percent effective in detecting errors. These methods work by adding extra bits to the data to detect and correct errors during transmission. The vertical redundancy check checks for errors in each column of data, while the longitudinal redundancy check checks for errors in each row of data. By combining these two methods, a high level of error detection can be achieved.

The correct answer is Auxiliary current probe. An earth ground tester is used to measure the resistance of the earth ground electrode. In order to generate a known current, an auxiliary current probe is used. This probe is connected to the tester and provides a controlled current flow between the earth ground electrode and the grounding point. By measuring the voltage drop across the electrode, the resistance can be calculated. The other options, such as the inner earth stake and auxiliary potential probe, are not used for generating a known current in this context.

A charged coupled device (CCD) is a digital storage oscilloscope circuit that compensates for high sampling rates of high frequency signals. CCDs are able to capture and store a large amount of data quickly, making them suitable for high frequency signals. They work by converting the analog signal into digital form, allowing for accurate measurements and analysis of the signal. In contrast, an analog-to-digital converter converts analog signals into digital form, but it does not specifically compensate for high sampling rates of high frequency signals like a CCD does. A digital-to-analog converter and a cathode-ray tube are not directly related to compensating for high sampling rates of high frequency signals.

In the fall of ground testing method, voltage potential is measured between the auxiliary current electrode and the earth ground electrode. This is because the fall of ground testing method is used to measure the resistance of the earth ground system. By measuring the voltage potential between these two electrodes, the resistance can be calculated using Ohm's Law (V=IR). The auxiliary current electrode is used to inject a known current into the ground, and the voltage potential is then measured between this electrode and the earth ground electrode to determine the resistance.

The correct answer is "Radiated." When a weapon detonates, the interactions between the weapon products and the Earth's atmosphere produce an electromagnetic pulse (EMP) that is radiated outward. This radiated EMP is a distinct region of the source region, indicating that it is separate from the secondary, plasma, and source regions.

In acquiring a 4K record length on a digital storage oscilloscope, you can view 4,000 samples at one time. The record length refers to the number of samples or data points that the oscilloscope can capture and display at one time. In this case, the oscilloscope can capture and display 4,000 samples, allowing for a more detailed and accurate representation of the waveform being measured.

The correct answer is Pseudo random noise (PRN) synchronizer/comparator. The PRN synchronizer/comparator section of the BER test set generates its own pattern internally, which is then compared with the received data from the data/clock receivers. This allows for the detection and measurement of errors in the received data by comparing it with a known PRN pattern.

The scintillation effect in communications refers to the large attenuation of the transmitted signal, which results in a decrease in the received signal-to-noise ratio (SNR) to a level below unity. This attenuation is caused by various factors, such as multiple path propagation through the structured plasma field. As a result, the signal experiences fading and becomes weaker, leading to a reduced SNR and potentially causing communication disruptions.

The three types of digital storage oscilloscope acquisition modes are sample, peak detect, and averaging. The standard operating mode is sample.

An RF generator is a device used to generate radio frequency signals. It is commonly used in various applications such as troubleshooting receivers, checking antenna systems, and aligning telemetry receivers. However, verifying transmitter frequencies is not an application of an RF generator. This task is typically performed using a frequency counter or spectrum analyzer to accurately measure and verify the frequency output of a transmitter.

In Phase Modulation (PM), the phase of the carrier signal is shifted in accordance with the phase of the modulating signal. This means that the instantaneous phase of the carrier signal is modified based on the phase of the modulating signal. The amplitude of the carrier signal remains constant, as PM is primarily concerned with changing the phase. Therefore, the correct answer is "phase shifted with the phase of the modulating signal."

The correct answer is actual power level expressed in milliwatts. The abbreviation dBm is commonly used in power readings to indicate the power level in decibels relative to a 1-milliwatt standard. This means that the power level being measured is expressed in milliwatts.

The principal threat to electronics systems by cable is the local electromagnetic pulse (EMP) region. This region refers to the area in close proximity to the source of the EMP, where the electromagnetic energy is strong enough to induce damaging currents and voltages in cables and other conductive materials. The local EMP region poses a significant risk to electronics systems as it can cause disruptions, malfunctions, or even permanent damage to the components connected by cables.