Langley CST - 3D151 Vol 2

Condensation occurs when air particles are pressurized, causing them to move closer together. When air is pressurized, the particles are forced closer, reducing the space between them. As a result, the particles lose energy and slow down, leading to the formation of liquid droplets or solid particles. This process is commonly observed when warm air cools down, such as when warm moist air comes into contact with a cold surface, leading to the formation of dew or fog.

The human ear can detect sound within the frequency range of 20 to 20,000 Hz. This range is commonly referred to as the audible range for humans. Frequencies below 20 Hz are known as infrasound and frequencies above 20,000 Hz are known as ultrasound, which are typically not audible to the human ear. Therefore, the correct answer is 20 to 20,000 Hz.

The loudness of a sound is closely related to the amplitude of the sine wave. Amplitude refers to the maximum displacement of the particles in a medium as a sound wave passes through it. A higher amplitude corresponds to a louder sound, as it represents a greater amount of energy being transferred by the wave. Therefore, the correct answer is amplitude.

Noise can be introduced into speech signals by various factors, including thermal agitation and black body radiation. Thermal agitation refers to the random movement of particles due to their thermal energy, which can cause fluctuations in the signal. Black body radiation refers to the emission of electromagnetic radiation by a perfect black body, which can also contribute to the introduction of noise in speech signals. Therefore, black body radiation is a valid explanation for the introduction of noise in speech signals.

The maximum number of ports that a Meridian System Logic (MSL)-100 will support is 30,000. This means that the MSL-100 can handle a large number of connections or devices simultaneously. It is important for the system to support a high number of ports in order to accommodate a large volume of incoming and outgoing data traffic. This capability is crucial for organizations or businesses that require a robust and scalable communication system.

The correct answer is 30. The question is asking about the type of digital signal protocol used as a message carrier between the Digital Multiplex System (DMS)-Bus and the network modules (NM) and input/output controller (IOC). The answer 30 suggests that the protocol used is likely DS-30, which is a digital signal protocol commonly used in telecommunications for transmitting voice and data signals.

On an Integrated Services Digital Network (ISDN) B-channel, user information is transmitted. This includes both voice and data from the user. The B-channel is responsible for carrying the actual content of the communication, whether it is a phone conversation or data transfer. This is in contrast to other types of information that may be transmitted on ISDN, such as call control, supervisory, or signaling information, which are not directly related to the user's content.

The correct answer is the coder/decoder (CODEC). In a video teleconferencing (VTC) system, the CODEC is responsible for converting analog signals, such as those from a camera, into digital signals that can be transmitted over a network. The CODEC also decodes digital signals received from the network back into analog signals for display on a screen or monitor. It plays a crucial role in ensuring the compatibility and quality of audio and video signals in a VTC system.

When a voice over Internet Protocol (VoIP) session is established between a private branch exchange (PBX) and another IP host, two channels are used, one for each direction. This means that there is a separate channel for transmitting audio from the PBX to the IP host, and another channel for transmitting audio from the IP host to the PBX. This allows for bidirectional communication between the two devices during the VoIP session.

A gatekeeper is a component of Voice over Internet Protocol (VoIP) that provides call management functions in a defined local area called a zone. It acts as a central control point for managing and directing calls within the network. It authenticates and authorizes users, controls bandwidth allocation, manages call routing, and provides other administrative functions. A gatekeeper ensures efficient and secure communication by regulating access and managing resources in the VoIP network.

Frequencies from 30 to 300 megahertz (MHz) are internationally designated as "Very high." This range of frequencies falls within the VHF (Very High Frequency) band, which is commonly used for various purposes such as FM radio broadcasting, television broadcasting, and aviation communication.

Impedance refers to the total resistive properties of a circuit when resistance, capacitive reactance, and inductive reactance are combined. It is a measure of how much a circuit resists the flow of alternating current. Impedance takes into account both the resistance and reactance components of a circuit, and it is represented by a complex number that includes both magnitude and phase. Impedance is important in analyzing and designing electrical circuits, as it determines how the circuit will respond to AC signals and affects the overall performance of the circuit.

To ensure optimal communication, it is important for the transmitting and receiving antennas to have the same polarization. Polarization refers to the orientation of the electric field of the radio waves being transmitted. When the polarization of both antennas is aligned, it allows for better reception and transmission of the signals. If the antennas have different polarizations, there may be significant signal loss and reduced communication efficiency. Therefore, having the same polarization between the transmitting and receiving antennas is crucial for effective communication.

The correct answer is Isotropic. An isotropic antenna is a theoretical concept used as a reference for antenna gain comparison. It radiates equally in all directions and has a gain of 0 dBi. It is used as a standard for measuring the performance of other antennas, which are compared to the isotropic antenna to determine their gain.

The gain of an antenna refers to its ability to focus and amplify signals in a specific direction. When comparing the gain of an anisotropic radiator (directional antenna) to an isotropic radiator (omnidirectional antenna), the stronger signal of the directional antenna is expressed in decibels (dB) gain. Decibels is a logarithmic unit used to measure the ratio of power or intensity, and in this case, it quantifies the increase in signal strength provided by the directional antenna compared to the isotropic radiator.

Direct waves, also known as line-of-sight waves, travel in a straight line from the transmitter to the receiver. However, the curvature of the earth limits the range of these waves. As the distance between the transmitter and receiver increases, the earth's curvature causes the direct wave to gradually bend away from the receiver, resulting in a loss of signal strength. This phenomenon is particularly noticeable at longer distances, and it is the reason why direct waves are typically limited to less than 20 miles.

Fog is the correct answer because it attenuates radio frequency (RF) energy just like rain. Fog consists of tiny water droplets suspended in the air, which can cause the RF energy to scatter and be absorbed, leading to a decrease in signal strength. This attenuation effect is similar to what happens with rain, where the water droplets in the atmosphere interfere with the transmission of RF signals. Therefore, fog can have a similar impact on RF communication as rain does.

The ratio used to measure the desired signal strength relative to the background noise is called signal-to-noise. This ratio indicates how much stronger the desired signal is compared to the unwanted noise present in the background. A higher signal-to-noise ratio indicates a stronger and clearer signal, while a lower ratio indicates a weaker and more distorted signal. It is an important measure in various fields, including telecommunications, audio processing, and data analysis.

The Family Radio Service (FRS) device was originally intended for use by family, friends, and associates to communicate among themselves within a small area. FRS devices are commonly used for recreational activities, such as camping or hiking, where a group needs to stay in contact with each other. These devices operate on specific channels and have limited range, making them suitable for short-range communication within a small group.

Before removing and replacing terminal or distribution frame protectors, it is important to measure the voltage across them to ensure that dangerous voltages are not present on the line. This is crucial for the safety of the person performing the task as well as to prevent any potential damage to the equipment or circuits. By measuring the voltage, one can determine if it is safe to proceed with the removal and replacement process without risking any harm or accidents.

BAM and CAM are both access modules that provide a secure data network to local subscribers. However, the difference lies in their capabilities. While CAM has a fixed capability, BAM also has a fixed capability. This suggests that both modules have a specific set of features or functions that cannot be modified or expanded upon.

The actual voice frequency band, measured in hertz (Hz), ranges from 300 to 3,400. This means that the human voice typically produces sound waves within this frequency range.

The correct answer is DMS-100 and Meridian System Logic (MSL)-100. These models of end offices in the Digital Multiplex System (DMS) family are commonly used at Air Force bases to provide base telephone services.

DS-30A is the correct answer because it is the type of link that is typically used to interconnect two peripheral modules (PM) in the Digital Multiplex System (DMS). The DS-30A link provides a transmission rate of 30 Mbps, which is suitable for connecting peripheral modules and transferring data between them efficiently.

In a Digital Multiplex System (DMS), the mounting bracket on which transmission or switching equipment is mounted is called a "Bay." This term is commonly used in telecommunications to refer to a specific area or enclosure where the equipment is housed. Bays are designed to provide a secure and organized space for the installation and maintenance of various components, such as cards, shelves, and frames.

A frame contains bays of the same functional equipment. Bays are compartments or sections within a frame that hold specific equipment. Frames are typically used in industries such as telecommunications or data centers to organize and house equipment efficiently. Each bay within a frame can hold similar equipment, making it easier to manage and access.

The peripheral module's (PM) peripheral processor (PP) uses either a 16-bit Motorola 68000 or an 8-bit Intel microprocessor in the Digital Multiplex System (DMS). This component is responsible for controlling and managing the peripheral devices connected to the DMS. It handles the communication between the peripheral devices and the computing module's central processing unit (CPU). The choice of microprocessor depends on the specific requirements and capabilities of the DMS.

Each digital signal (DS) 30 speech link carries 32 channels of data.

The line group controller (LGC) is connected to the network module (NM) using duplicated digital signals (DS)-30 links. The question is asking for the maximum number of DS-30 links that can be used for this connection. The correct answer is 16, which means that up to 16 DS-30 links can be used to connect the LGC to the NM.

In pulse code modulation (PCM), the first step is to band-limit the analog signal. This means that the signal is filtered to remove any frequencies that are outside the desired range. Band-limiting is necessary to prevent aliasing, which can distort the signal during the sampling process. By limiting the bandwidth of the analog signal, it ensures that only the desired frequencies are captured accurately during the sampling process.

In the pulse code modulation (PCM) process, changing the quantized samples into a binary word is called encoding. This is because encoding involves converting the analog signal into a digital format by assigning specific binary codes to each quantized sample. The binary word represents the amplitude of the signal at a given point in time and is used for transmission or storage purposes. Sampling refers to the process of measuring the amplitude of the analog signal at regular intervals, quantization is the process of approximating the continuous analog signal into discrete levels, and band limiting refers to restricting the frequency range of the signal.

The correct answer is Basic rate interface and primary rate interface. ISDN is a telecommunications network that provides digital transmission of voice, video, and data over traditional telephone lines. The Basic rate interface (BRI) is designed for residential and small business use, offering two B channels for data and one D channel for signaling. The Primary rate interface (PRI) is intended for larger businesses, providing 23 B channels and one D channel in North America, and 30 B channels and one D channel in Europe. These two transmission rates are the major established options for ISDN connections.

The Network Layer of the OSI model is responsible for the actual routing of the signal. This layer takes care of determining the best path for the data packets to travel from the source to the destination across different networks. It handles tasks such as addressing, packet forwarding, and routing protocols. By analyzing the network topology and making decisions based on routing tables, the Network Layer ensures that data packets are efficiently delivered to their intended destinations.

The main purpose of the Integrated Services Digital Network (ISDN) handset telephone test set is to verify a dial tone. This means that the test set is used to check if a dial tone is present and functioning properly on the telephone line. It ensures that the user can make outgoing calls successfully by confirming the availability of a dial tone.

The frame rate in feet per second (FPS) for transmitting video teleconferencing data on the Integrated Services Digital Network (ISDN) is 30. This means that 30 frames of video are transmitted every second over the ISDN network.

In order to implement voice over Internet Protocol (VoIP), the one-way delay from endpoint to endpoint should be less than 150 milliseconds. This is because any delay greater than this can result in noticeable voice quality degradation and communication issues. Therefore, to ensure smooth and real-time communication, it is important to keep the one-way delay below 150 milliseconds.

A phase-locked loop (PLL) is a control system that generates a signal with a fixed relation to the phase of a reference signal. It not only responds to the frequency but also the phase of the input signals. In other words, a PLL locks onto the phase of a reference signal and adjusts the frequency and phase of its output signal accordingly. This makes it a suitable control system for applications that require precise synchronization and tracking of phase and frequency, such as in communication systems, audio/video equipment, and clock generation.

Heterodyning is the process of mixing or combining two frequencies in a nonlinear device in an amplitude modulated (AM) receiver. This technique is used to convert the received signal to a lower frequency, known as the intermediate frequency (IF), which is easier to process and amplify. By mixing the received signal with a local oscillator signal, a new frequency is generated in the IF range, allowing for easier filtering and amplification of the desired signal. Heterodyning is a crucial step in the demodulation process of an AM receiver.

The discriminator is the component of a frequency modulated (FM) receiver that removes the original signal from the sidebands and recreates the audio intelligence. It does this by demodulating the FM signal and converting it back into an audio signal. The discriminator is responsible for extracting the audio information from the FM carrier wave and restoring it to its original form.

Selectivity is the characteristic that enables a receiver to reproduce a desired signal from several closely spaced stations or from interfering frequencies. It refers to the ability of a receiver to separate and extract the desired signal while rejecting unwanted signals or interference. A selective receiver is able to filter out unwanted frequencies and only amplify and process the specific frequency or range of frequencies that it is tuned to receive. This allows for clear and accurate reproduction of the desired signal, even in the presence of nearby stations or interfering frequencies.

Radiation is the correct answer because it refers to the process in which radio frequency (RF) signals detach from the conductor and travel through space. RF signals are electromagnetic waves that propagate through space without the need for a physical medium. This is the fundamental principle behind wireless communication systems such as radio, television, and cellular networks.

An antenna can be made resonant at the shortest wavelength by using a half-wavelength design. This means that the length of the antenna is half the wavelength of the signal it is designed to receive or transmit. This design allows for efficient transfer of energy between the antenna and the electromagnetic waves, maximizing the antenna's performance. Using a quarter-wavelength design would not be sufficient for resonant operation, as it would result in poor impedance matching and reduced efficiency.

Time division multiple access (TDMA) is a channel access method that assigns each call a certain portion of time on a designated frequency. This means that multiple calls can be transmitted simultaneously by dividing the available time into smaller time slots. Each call is allocated a specific time slot, allowing multiple calls to share the same frequency without interfering with each other. TDMA is commonly used in cellular networks to maximize the efficiency of frequency spectrum utilization.

Cell sites are generally thought of as being a hexagon because the coverage area of a cell site is typically divided into hexagonal shapes. This is because hexagons provide the most efficient and uniform coverage, allowing for the least amount of overlap and the best distribution of signal strength. The use of hexagons also helps to minimize interference between neighboring cell sites and maximize the overall capacity and performance of the cellular network.

A base station is the correct answer because it serves as the central hub of a network in conventional land mobile radio (LMR) systems. It is a fixed station that communicates with portable and mobile radios within its coverage area. The base station typically has a more powerful transmitter and receiver compared to portable and mobile devices, allowing it to provide wider coverage and better communication quality. It acts as a central control point for managing and coordinating communication activities within the network, making it an essential component for LMR systems.

In trunked land mobile radio (LMR) systems, different user groups are known as talkgroups. Talkgroups are a way to organize and categorize users within the system. Each talkgroup is assigned a unique identifier and users within the same talkgroup can communicate with each other. This allows for efficient and organized communication within the LMR system, as users can easily select and connect with the specific talkgroup they need to communicate with. Channels, packets, and nets are not the correct terms used to refer to user groups in trunked LMR systems.

Inmarsat coverage is divided into ocean areas. This means that their satellite communication services are specifically designed to cover maritime regions and provide connectivity for ships and vessels at sea.

The Meridian System Logic (MSL)-100 model of Digital Multiplex System (DMS)-100 family switches is installed in compact modular cabinets.

The central side (C-side) of a network module (NM) in the Digital Multiplex System (DMS) is connected to the central control. This means that the central control is the major area connected to the C-side of the NM. The central control is responsible for managing and controlling the overall operation of the DMS network. It coordinates the functions of various modules and ensures efficient communication within the system.

CompuCALL is the correct answer because it is an application that provides local area network (LAN) connectivity, allowing users to share equipment, data files, and application software using a modem. This application enables communication and collaboration among users within a LAN environment, enhancing productivity and efficiency.