Term
| 1. What term describes complete oscillations an electromagnetic wave makes per second? |
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Definition
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Term
| 2. 30 MHz to 300 MHz defines what international frequency division? |
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Definition
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Term
| 3. Define one wavelength. |
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Definition
| The distance in space occupied by one cycle of a radio wave at any given instant. |
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Term
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Definition
| The process by which the characteristics of the RF carrier signal are varied with the intelligence signal. |
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Term
2. Which mode of operation supports communications between two or more stations in both directions
simultaneously? |
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Definition
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Term
| 3. What device allows a single antenna to be used for both transmitting and receiving? |
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Definition
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Term
| 4. What are the two basic stages of an amplitude modulated transmitter? |
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Definition
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Term
| 5. At what rate is the RF oscillator’s frequency varied by the FM modulator? |
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Definition
| At the rate of the modulating-AF. |
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Term
| 6. Define a transmitter’s frequency accuracy. |
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Definition
| Its ability to maintain a constant output carrier frequency. |
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Term
7. What term is used to describe the process of mixing or combining two frequencies in a nonlinear
device? |
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Definition
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Term
8. Which receiver characteristic describes its ability to select and reproduce a desired signal from among
several closely spaced stations or interfering signals? |
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Definition
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Term
1. Two-wire transmission lines exhibit the properties of a circuit that contains what electronic
components? |
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Definition
| Resistors, capacitors, and inductors (RCL circuit). |
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Term
2. When RF energy is applied to the transmission line, it causes the capacitors and inductors to exhibit
what property? |
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Definition
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Term
| 3. On what property is transmission line capacitive and inductive reactance dependent? |
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Definition
| The frequency the transmission line is carrying. |
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Term
| 4. Why is impedance matching between the transmitter and transmission line important? |
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Definition
| We want as much transmitter output power to the antenna as possible. |
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Term
| 5. Which type of coaxial cable is most commonly seen in a tactical environment? |
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Definition
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Term
| 6. What type of coaxial cable is best suited for underground cable runs? |
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Definition
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Term
| 1. Name the two parts of the electromagnetic wave. |
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Definition
(1) Electric fields (E-lines).
(2) Magnetic fields (H-lines). |
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Term
2. As RF is applied to an antenna, the E- and H-lines are components that combine to form two different
electromagnetic fields. What are the two fields and which field travels and makes radio
communications possible? |
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Definition
| Induction field and radiation field; radiation field. |
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Term
| 3. What shows the radiation characteristics of a specific antenna? |
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Definition
| Antenna radiation patterns. |
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Term
4. What type of polarization occurs when the antenna's transmitted E-lines are perpendicular to the
Earth’s surface? |
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Definition
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Term
5. Any antenna transfers RF energy from space to its terminals with the same efficiency that it transfers
RF energy from its terminals into space. What antenna property does the preceding statement define? |
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Definition
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Term
| 6. What are the two types of radiators? |
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Definition
(1) Isotropic.
(2) Anisotropic. |
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Term
| 7. The sun is a good example of what type of radiator? |
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Definition
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Term
8. What term describes all practical RF radiators that emit stronger radiation in one direction than
another? |
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Definition
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Term
9. The difference in strength between the signal received from an isotropic radiator and the signal
received from the directional antenna is the gain of the directional antenna. In what unit of
measurement is this gain expressed? |
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Definition
| Decibels (dB) or decibels isotropic (dBi). |
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Term
| 10. If the resonant antenna is fed with other than its resonant frequency, what will happen? |
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Definition
Much of the input signal's power will be turned back down the transmission line and cause destructive standing
waves. |
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Term
| 11. How much bandwidth do most resonant antennas have? |
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Definition
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Term
| 12. Why can the length of an antenna be cut? |
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Definition
| So that the inductive and capacitive reactance is equal and the antenna is effectively a resonant circuit. |
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Term
13. For impedance matching on the resonant antenna, by what is antenna impedance or radiation
resistance greatly varied? |
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Definition
| Where the transmission line connection is made on the antenna. |
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Term
14. When a nonresonant antenna is impedance matched, what would be an acceptable standing wave ratio
reading? |
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Definition
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Term
| 15. What is the greatest cause of decreased antenna efficiency? |
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Definition
| The antenna converts the electrical energy from the transmission line into the radiated electromagnetic fields. |
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Term
| 16. What type of antenna radiates radio energy in a circular pattern? |
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Definition
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Term
| 1. How far can direct waves continue to travel in a straight line? |
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Definition
| Until they are interrupted by an object or weaken over a great distance. |
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Term
| 2. Why are frequencies above VHF normally limited to less than 20 miles? |
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Definition
| Due to the curvature of the Earth. |
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Term
| 3. The ability to visually sight a transmitting antenna roughly corresponds with the ability to receive a signal from it, is called what? |
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Definition
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Term
| 4. What obstructions might obscure a visual link? |
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Definition
Trees, the curvature of the Earth, buildings and other man-made objects, and topographic features such as
mountains. |
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Term
| 1. What type of precipitation attenuation has a pronounced degrading effect on microwave energy? |
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Definition
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Term
| 2. Which type of precipitation causes frequencies above 2 GHz to be seriously attenuated? |
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Definition
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Term
| 3. What aspects of hail determine how much it will attenuate a signal? |
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Definition
| Size and density of the stones. |
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Term
| 4. Define signal-to-noise ratio. |
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Definition
| A measure of desired signal strength relative to the background noise. |
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Term
| 5. Why is power line interference difficult to determine? |
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Definition
| The power lines act as antennas that radiate the interference. |
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Term
| 6. How can we minimize interference from motors and generators with commutators and slip rings? |
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Definition
| Maintain brushes and slip rings in good condition. |
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Term
| 7. What can happen when cables are improperly routed? |
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Definition
They can have high levels of noise inductively coupled to nearby wiring, resulting in poor audio quality and
high error rates. |
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Term
| 1. What AFI governs PWCS management? |
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Definition
AFI 33–106, Managing High Frequency Radios, Personal Wireless Communications Systems, and the Military
Affiliate Radio System. |
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Term
| 2. What is the only authorized Air Force inventory control software for PWCS assets? |
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Definition
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Term
| 3. List some wireless services to consider when determining PWCS technical solutions. |
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Definition
LMRs, pagers, cellular and PCS services, mobile satellite services, joint tactical radio system, and enhanced
special mobile radios. |
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Term
| 4. For the most part, how is government-owned radio PWCS equipment maintained? |
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Definition
| Under civilian contract, but some bases do perform “blue-suit” maintenance. |
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Term
| (1) Small, cheap digital radios that you may have seen for sale at a sports store in the Base Exchange. |
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Definition
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Term
| (2) Radios that operate on 14 channels in the 380-399.0 MHz band. |
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Definition
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Term
(3) Small mobile handheld device that provides computing and
information storage and retrieval capabilities. |
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Definition
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Term
(4) A fast, secure, and convenient method of communication for
people engaged in various career fields. |
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Definition
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Term
| (5) A basic simplex receiver that receives on only one channel. |
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Definition
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Term
| (6) A point-to-point, common carrier service. |
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Definition
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Term
| 2. What is the advantage of LMR radios? |
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Definition
They are quick to set up, rugged, operate with or without a fixed infrastructure, and are authorized for command
and control purposes. |
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Term
| 1. At what frequency range do cell phones operate? |
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Definition
| Somewhere in the 800 MHz to 2 GHz range depending on the provider. |
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Term
(1) Gives a unique code to each call and spreads it over the available
frequencies. |
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Definition
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Term
| (2) Puts each call on a separate frequency. |
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Definition
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Term
(3) Emphasis is on personal with things like text messaging and
email built in. |
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Definition
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Term
(4) It is an international standard that uses encryption to make phone
calls more secure. |
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Definition
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Term
(5) Assigns each call a certain portion of time on a designated
frequency. |
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Definition
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Term
| 3. Describe cell phone coverage. |
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Definition
Each cell in a service area has a central tower and transceiver assembly that transmits to and receives from the
cell phones in that area. |
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Term
| 4. Who is usually responsible for their airtime charges and must budget accordingly? |
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Definition
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Term
5. Why are cell phones and local landline systems virtually unusable in the event of local emergencies
or natural disasters? |
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Definition
| There is a high chance that the cell and landline systems will instantly be jammed with incoming calls. |
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Term
| 6. What are the disadvantages of a government-owned cellular system? |
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Definition
| Initial cost and the costs that are incurred to utilize new technology as it becomes available. |
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Term
| 1. Generally how are cell phones able to cover a very large area with relatively few frequencies? |
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Definition
An area of coverage is divided into cells, which allows service providers to reutilize a band of frequencies
within a coverage area so that thousands of users can utilize their cell phones simultaneously. |
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Term
| 2. What is cell service based on? |
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Definition
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Term
| 1. What are some of the advantages of a conventional LMR system? |
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Definition
They are cost effective and easy to maintain, and their limited infrastructure ensures that communication is
possible in the event of a catastrophic failure. |
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Term
| 2. When you key and speak into a radio, who can hear you? |
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Definition
| Everyone on that particular channel. |
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Term
| 3. What are the limitations of a single-site configuration? |
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Definition
| The user radio must be within the range of coverage of the repeater, base station, or other radio asset. |
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Term
4. What process is employed to ensure that the best audio from multiple receivers is processed and
eliminate echo? |
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Definition
| A receiver voting system is employed. |
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Term
| 5. Differentiate the primary difference between a simulcast and multicast system. |
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Definition
Simulcast system transmit on the same frequency simultaneously from each transmitter, while multicast systems
use a different set of frequencies at each site. |
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Term
(1) Permits users to make and receive telephone calls over
a LMR net. |
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Definition
| Telephone interconnect equipment. |
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Term
| (2) Designed to retransmit radio signal. |
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Definition
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Term
| (3) Transceiver installed in buildings. |
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Definition
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Term
| (4) Vehicular mounted transceiver. |
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Definition
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Term
| (5) Designed for personal use. |
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Definition
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Term
| (6) Serves as the hub of a net. |
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Definition
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Term
| (7) Antennal mounted high above the terrain. |
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Definition
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Term
| (8) Antenna mounted on roof or trunk of vehicle. |
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Definition
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Term
| 1. What does a trunked radio system do? |
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Definition
| It automatically and dynamically allocates a small number of radio channels to support a large number of users. |
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Term
| 2. What makes up the central repeater site? |
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Definition
| The CC, repeaters, antenna combining equipment, and antennas. |
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Term
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Definition
A computer based system that keeps track of all the users and resources in the system. It receives a request for
services, verifies it is a valid request, and assigns the talkgroup an available repeater to service the requested
call. |
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Term
| 4. How many talkgroups can a portable radio monitor at one time? |
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Definition
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Term
| 5. List the advantages of using a trunking system. |
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Definition
(1) Frequency conservation.
(2) Increased coverage.
(3) Enhanced features.
(4) Guaranteed access during contingencies.
(5) Graceful degradation. |
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Term
| 6. What does the selective radio inhibit feature allow the system manager to do? |
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Definition
| Completely disable radios in the field from the system terminal. |
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Term
1. The DOD policy on procurement of MSS required that handheld MSS services be provided by
Iridium unless a waiver was granted. Is that policy still effective? |
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Definition
The policy is still active but was amended in 2006 to allow the DOD to use other mobile satellite service
providers, for unclassified purposes only, when both the source and destination are within the CONUS. |
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Term
| 2. What allows Iridium to offer coverage to all parts of the globe including the poles? |
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Definition
| A constellation of 66 cross-linked satellites in near polar low Earth orbit. |
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Term
| 3. What is the purpose of the dedicated government EMSS gateway? |
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Definition
| Provides a dedicated entry point from the Iridium network into the DISN for secure and non-secure services. Also provides entry to non-secure commercial telephone services. |
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Term
| 4. What is required when using the Iridium handheld phone for voice communications? |
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Definition
| Handheld voice communications must be secured using the Iridium secure module. |
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Term
| 1. What is a major requirement of the Inmarsat charter? |
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Definition
| That the Inmarsat system must be used exclusively for peaceful purposes. |
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Term
| 2. List the peaceful purpose clause guidelines for military use of the Inmarsat system? |
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Definition
(1) Armed forces not involved in armed conflict or any threat to or breach of peace may use Inmarsat.
(2) UN peacekeeping or peacemaking forces acting under the auspices of the UN Security Council may use
Inmarsat, even if engaged in armed conflict, to accomplish their mission.
(3) Armed forces not acting under the auspices of the UN Security Council involved in international or noninternational
armed conflict (civil war) may not use Inmarsat, except in the case of legitimate individual or
collective self-defense against armed attack within the limitations established by UN charter, Article 51.
This exception excludes preventive action and self-help involving armed force in the absence of armed
attack.
(4) Armed forces engaged in armed conflict may use Inmarsat for distress and safety communications and for
communications relating to the protection of the wounded, sick, shipwrecked, prisoners of war, and
civilians pursuant to the Geneva Red Cross Conventions, 1977. Personal and private, non-tactical
communications by members of the armed forces are permitted; however, use of Inmarsat for nontactical
governmental communications related to or in support of the war effort are not permitted unless they
originate from governments of, or are directed to armed forces engaged in activities sanctioned by the UN
Security Council, or self-defense pursuant to UN Charter, Article 51. |
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Term
| 3. Describe the Inmarsat constellation and its area of coverage. |
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Definition
Inmarsat provides worldwide coverage from about 82 degrees North latitude to about 82 degrees South latitude
using geosynchronous satellites. Inmarsat currently has twelve active satellites in its constellation. Each satellite
provides three different types of coverage: global beam footprints cover roughly one third of the Earth, narrow
spot beam provides tighter coverage with more power, and wide spot beam covers most areas of interest to its
customers. Coverage is separated into different ocean areas (East Atlantic, West Atlantic, Pacific, and Indian)
with large overlaps. |
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Term
(1) Uses portable, notebook-sized terminals typically weighing less than 6 lbs
(2.7 kg). Provides up to voice at 4.8 Kbps, fax and data at 2.4 Kbps,
Internet access, and email. This service is provided via satellite spot beams. |
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Definition
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Term
(2) Also called global area network. Provides voice at 4.8 or 64 Kbps, data at
various rates up to 64 Kbps, and fax at 2.4 Kbps. |
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Definition
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Term
(3) Provides aircraft with one to four simultaneous voice or data channels.
Capabilities include digital voice at 4.8 Kbps, fax and real-time data at 2.4
Kbps, and cockpit data at up to 1.2 Kbps. Used in narrow-bodied aircraft
and ICAO/SARPS compliant. |
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Definition
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Term
(4) Provides digital voice at 4.8 Kbps and low-speed data and fax
communications at 2.4 Kbps. Land mobile units are typically
briefcase-sized portable terminals with a flat array antenna. |
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Definition
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Term
(5) Accommodates full duplex data at up to 64 Kbps, voice at 16 Kbps,
and fax at up to 9.6 Kbps. Terminals typically have a one meter flat
array antenna and weighs between 30 and 40 lbs. |
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Definition
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Term
(6) Provides one channel of voice at 4.8 Kbps, fax at 2.4 Kbps, or data
services using a small, lightweight terminal. Operates in the Inmarsat
spot beams and is ideal for small aircraft. It is not ICAO/SARPS
compliant. |
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Definition
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