Eidws Common Core 113

Front 1

Define ELF, its band and use.

Back 1

ELF- Extremely Low Frequency; <= 3KHz, Submarine (PLSO) Broadcast
Long Range Over/Under Ocean

Front 2

Define VLF, its band and use.

Back 2

VLF- Very Low Frequency; 3-30KHz, Timing/Navigation/Synchronization
Long Range Over/Uner Ocean

Front 3

Define LF, its band and use.

Back 3

LF- Low Frequency; 30-300KHz, Fleet Multi-channel Broadcast
Stable not affected by ionospheric disturbances

Front 4

Define MF, its band and use.

Back 4

MF- Medium Frequency; 300KHz-3MHZ, Intl. Distress Freqs., S&R, AM Radio
Long Distance Over Water, Short haul over land

Front 5

Define HF, its band and use.

Back 5

HF- High Frequency; 3-30MHz, Long range terrestrial radio
Easily modulated, RTW Comms via ionospheric refraction

Front 6

Define VHF, its band and use.

Back 6

VHF- Very High Frequency; 30-300MHz, LOS, FM Radio, HAM
LOS, unaffected by static, Amphibious Operations

Front 7

Define UHF, its band and use.

Back 7

UHF- Ultra High Frequency; 300MHz-3GHz, Microwave, Tactical voice, Wireless
LOS, unaffected by static, Tactical Voice

Front 8

Define SHF, its band and use.

Back 8

SHF- Super High Frequency; 3GHz-30GHz, RADAR, SATCOM, Wireless
LOS, Unaffected by Static, RADAR, SATCOM

Front 9

Define EHF, its band and use.

Back 9

EHF- Extremely High Frequency; 30GHz-300GHz, Astronomy, Experimental

Front 10

Define Frequency.

Back 10

Frequency The number of cycles that occur in one second; (Hz).

Front 11

Define Wavelength.

Back 11

Wavelength – The distance from any point on a cycle to the corresponding point on the next cycle.

Front 12

Define Refraction

Back 12

Refraction – The bending of RF waves as they pass through mediums of different density.

Front 13

Define Ducting

Back 13

Ducting – Trapping of an RF wave between two layers of the earth's atmosphere or between an atmospheric layer and the earth.

Front 14

Define Multiplexing

Back 14

Multiplexing - A method for simultaneous transmission of two or more signals over a common carrier wave.

Front 15

Define modulation/demodulation.

Back 15

Modulation/Demodulation – The ability to impress intelligence upon a medium, such as radio waves. Demodulation is the process of reversing modulation.

Front 16

Define bandwidth

Back 16

Bandwidth – The section of the frequency spectrum that specific signals occupy

Front 17

Define Keying

Back 17

Keying – Changing the characteristic of a signal by opening and closing a key. Can be Frequency (FSK) or Phase (PSK).

Front 18

Define Azimuth Angle

Back 18

Azimuth Angle- (aka Bearing) Angular measurement in the horizontal plane in a clockwise direction.

Front 19

Define Elevation

Back 19

Elevation- The angle between the horizontal plane and the line of sight.

Front 20

Discuss Layers and give a description in regard to the atmosphere.

Back 20

Layers- sections of the atmosphere of different temperature and density; Troposhere (weather), Stratosphere (nothing), Ionosphere (D, E, F1 and F2 sublayers)

Front 21

Discuss Frequency and give a description in regard to the atmosphere.

Back 21

Frequency- For successful communications between any two specified locations at any given time of the day there is a maximum frequency, a lowest frequency, and an optimum frequency that can be used.

Front 22

Discuss Radio Waves and give a description in regard to the atmosphere.

Back 22

Radio Waves- The influence exerted on radio waves by the Earth's atmosphere adds many new factors to complicate what at first seems to be a relatively simple problem. These complications are because of a lack of uniformity within the Earth's atmosphere. Atmospheric conditions vary with changes in height, geographical location, and even with changes in time (day, night, season, year).

Front 23

Discuss Propagation and give a description in regard to the atmosphere.

Back 23

Propagation- The path that a refracted wave follows to the receiver depends on the angle at which the wave strikes the ionosphere.

Front 24

Describe USB modulation and its common usage.

Back 24

USB- All the sum frequencies above the carrier are spoken of collectively as the UPPER SIDEBAND. Used in HAM Radio.

Front 25

Describe LSB modulation and its common usage.

Back 25

LSB- All difference frequencies below the carrier, also considered as a group, are called the LOWER SIDEBAND. Used in HAM Radio.

Front 26

Describe CW modulation and its common usage.

Back 26

CW- A radio wave of a constant amplitude, phase and constant frequency. Morse Code.

Front 27

Describe AM modulation and its common usage.

Back 27

AM- Any method of varying the amplitude of a carrier wave in accordance with the intelligence being transmitted. Shortwave/ Talk radio.

Front 28

Describe FM modulation and its common usage.

Back 28

FM- Angle modulation in which the frequency (angular rate) of the carrier wave is caused to vary in accordance with the instantaneous amplitude variations of the modulating wave. Music and complex communications.

Front 29

Define PRI as they apply to RADAR

Back 29

PRI- Pulse Repetition Interval. The time between a point on the pulse to the identical point on the next pulse.

Front 30

Define PRF as they apply to RADAR

Back 30

PRF- Pulse Repetition Frequency. The number of pulses-per-second (PPS).

Front 31

Define RF as they apply to RADAR

Back 31

RF- Radio Frequency. Invisible waves of electromagnetic energy.

Front 32

Define BW as they apply to RADAR

Back 32

BW- Bandwidth width of a radar beam measured between half power points

Front 33

Define CW as they apply to RADAR

Back 33

CW- Continuous Wave. A RADAR of constant amplitude, phase, and frequency. Uses the Doppler Effect.

Front 34

Define PW as they apply to RADAR

Back 34

PW- Pulse Width. The time between the leading and trailing edges of a pulse.

Front 35

Define Scan as they apply to RADAR

Back 35

Scan- Systematic movement of a radar beam to cover a definite pattern or area in space.

Front 36

Define Bearing/Azimuth/Elevation as they apply to RADAR

Back 36

Bearing/Azimuth- Angle measured clockwise from True North in the horizontal plane.

Elevation- The angle between the horizontal plane and the line-of-sight. (altitude)

Front 37

Identify Air Search RADAR its function and a example.

Back 37

Air Search- Detect and determine the position, course, and speed of air targets in a relatively large area.

Maximum range of air-search radar can exceed 300 miles, and the bearing coverage is a complete 360-degree circle.

Used as early-warning devices because they can detect approaching enemy aircraft or missiles at great distances.

Front 38

Identify Surface Search RADAR its function and a example.

Back 38

Surface Search- Used to detect the presence of surface craft and low flying aircraft and to determine their presence. Used extensively as a navigational aid in coastal waters and in poor weather conditions.

Two Primary Functions

The detection and determination of accurate ranges and bearings of surface objects and low-flying aircraft.

To maintain a 360-degree search pattern for all objects within line-of-sight distance from the RADAR antenna.

Front 39

Identify Fire Control RADAR its function and a example.

Back 39

Fire Control- Usually produce a very narrow, circular beam.

Three Phases

Designation Phase – RADAR is directed to the general location of the desired target because of the narrow-beam pattern.

Acquisition Phase - RADAR system searches a small volume of space in a prearranged pattern until the target is located.

Tracking Phase – Once the target is located, the RADAR system automatically follows all target motions. The RADAR system is said to be locked on to the target during track phase.

Front 40

Explain the difference between OPELINT and TECHELINT

Back 40

OPELINT- Operationally relevant information such as the location, movement, employment, tactics, and activity of foreign noncommunications emitters and their associated weapon systems.

TECHELINT- Technical aspects of foreign noncommunications emitters such as signal characteristics, modes, functions, associations, capabilities, limitations, vulnerabilities, and technology levels.

Front 41

Define Half Duplex

Back 41

Half Duplex- The half-duplex (hdx) mode has one-way flow of information between terminals. Technical arrangements often permit transmission in either direction, but not simultaneously.

Front 42

Define Duplex

Back 42

Duplex- The full-duplex (fdx) mode is a method of operation in which telecommunications between stations takes place simultaneously in both directions using two separate frequencies.

Front 43

Define Simplex

Back 43

Simplex- SIMPLEX.—The simplex (splx) mode uses a single channel or frequency to exchange information between two or more terminals. Communications is in one direction only.