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EIDWS > 113 Technical Fundamentals > Flashcards

113 Technical Fundamentals Flashcards

1
Q

Define ELF (3-30Hz) and what signals are used

A

ELF (3-30Hz): EXTREMELY LOW; long range signals subs operating beyond normal mission depth
- Lower freq: deeper signal can be received underwater (rarely used due to extreme antenna size required)

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2
Q

Define SLF (30-300Hz) and what signals are used

A

SLF (30-300Hz): SUPER LOW; common power grid frequencies (50-60Hz); U.S. and Russian deep-sea communications

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3
Q

Define ULF (300Hz-3Khz) and what signals are used

A

ULF (300Hz-3Khz): ULTRA LOW; commonly used for radio communications in mines; excellent earth-penetrating properties. Also can be used for sub communications

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4
Q

Define VLF (3-30Khz) and what signals are used

A

VLF (3-30Khz): VERY LOW; Long range signals to subs operating at normal mission speeds & depths; crucial communications during hostilities & used as backup to communications blacked out by nuclear activity.

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5
Q

Define LF (30-300Khz) and what signals are used

A

LF (30-300Khz): LOW FREQ; Fleet multichannel broadcast system. Not seriously affected during ionospheric disturbance when communications at higher frequencies are disrupted

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6
Q

Define MF (300Khz-3Mhz) and what signals are used

A

MF (300Khz-3Mhz): MED FREQ; primarily by Navy for ground wave transmissions (lower portion of MF band); Commercial AM broadcasts (utilizes majority of MF range); includes international distress frequencies (500Khz/484Khz)

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7
Q

Define HF (3-30Mhz) and what signals are used

A

HF (3-30Mhz): HIGH FREQ; mostly common used for medium & long range terrestrial radio communications

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8
Q

Define VHF (30-300Mhz) and what signals are used

A

VHF (30-300Mhz): VERY HIGH FREQ; normally used for LOS or just beyond (Amphibious operations, FM broadcasts & amateur radio communications)

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9
Q

Define UHF (300Mhz-3Ghz) and what signals are used

A

UHF (300Mhz-3Ghz): ULTRA HIGH FREQ; LOS communications (tactical voice transmissions)

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10
Q

Define SHF (3-30Ghz) and what signals are used

A

SHF (3-30Ghz): SUPER HIGH FREQ; radar and satellite communications (normally used for LOS or just beyond)

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11
Q

Define EHF (30-300Ghz) and what signals are used

A

EHF (30-300Ghz) EXTREMELY HIGH FREQ; radio astronomy. Experimental stage

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12
Q

What is frequency?

A

of cycles that occur in one second (usually in hertz)

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13
Q

What is a wavelength?

A

The physical distance of a wave or cycle; (one 360 degree cycle)

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14
Q

Define ducting

A

Temperature or moisture conditions in atmosphere that allow a greater bending of radio waves

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15
Q

Define refraction

A

Wave that changes direction when passing from one medium into another

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16
Q

What is multiplexing?

A

For simultaneous transmission of two or more signals (either in time or frequency)

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17
Q

Define modulation

A

Impressing intelligence upon a transmission medium

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18
Q

Define demodulation

A

Extraction of intelligence upon a transmission medium

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19
Q

What is bandwidth?

A

Space within the radio frequency spectrum that a signal occupies

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20
Q

What is keying?

A

Inserting noise or data onto a frequency

21
Q

What is an Azimuth Angle?

A

Angular measurement in the horizontal plane in a clockwise direction

22
Q

What is an Elevation Angle?

A

Angle between horizontal plane and LOS (altitude)

23
Q

Discuss the Troposphere

A

Located between surface of Earth to about 3.7 miles at North Pole or South Pole and 11.2 miles at the equator

24
Q

Discuss the Stratosphere

A

Located between troposphere and ionosphere; little to no effect on radio waves

25
Q

Discuss the Ionosphere

A

Located upward from about 31.1 miles to about 250 miles; contains 4 cloud-like layers

26
Q

Discuss radio waves in relation to the atmosphere

A

Form of radiant energy that can neither be seen nor felt; electromagnetic wave generated by a transmitter

27
Q

Discuss propagation

A

Movement of a signal through a medium i.e. light rays

28
Q

Describe USB: Upper Sideband

A

The intelligence/data carrying section of a signal located adjacent to and HIGHER in frequency than the Center Frequency (CF)

29
Q

Describe LSB: Lower Sideband

A

The intelligence/data carrying section of a signal located adjacent to and LOWER in frequency than the Center Frequency (CF). The inverse (mirror) of the USB

30
Q

Describe CW: Carrier Wave

A

AKA “modulating wave”; carrier wave is the radio frequency which facilitates the transmission of intelligence across a medium

31
Q

Describe AM: Amplitude Modulation

A

Technique used in electronic communications, most frequently for transmitting information via a radio carrier wave

32
Q

Describe FM: Frequency Modulation

A

Conveys info over a carrier wave by varying its frequency

33
Q

Describe PRI (Pulse Repetition Interval) as it applies to RADAR

A

Duration of time the leading edge of one pulse to leading edge of another pulse

34
Q

Describe PRF (Pulse Repetition Freq) as it applies to RADAR

A

Rate at which pulses are transmitted (inverse of PRI)

35
Q

Describe RF (Radio Freq) as it applies to RADAR

A

Energy that is transmitted

36
Q

Describe BW (Bandwidth) as it applies to RADAR

A

The space within the RF spectrum that a signal occupies

37
Q

Describe CW (Continuous Wave) as it applies to RADAR

A

Unmodulated frequency that does not carry additional modulated intelligence

38
Q

Describe PW/PD (Pulse Width/Pulse Duration) as it applies to RADAR

A

Duration of time between the leading and trailing edge of the same pulse

39
Q

Describe Scan as it applies to RADAR

A

Systematic movement of a radar beam

40
Q

Describe Bearing as it applies to RADAR

A

Angle measured clockwise from true north in the horizontal plane

41
Q

Describe Azimuth as it applies to RADAR

A

Angular measurement in the horizontal plane in a clockwise direction

42
Q

Describe Elevation as it applies to RADAR

A

Angle between the horizontal plane and line-of-sight (altitude)

43
Q

Identify the type of RADAR: Air Search

A

Detect & determine position, course, & speed of air targets

44
Q

Identify the type of RADAR: Surface Search

A

Used to detect presence of surface craft & low flying aircraft

45
Q

Identify the type of RADAR: Fire Control

A

Produces a vary narrow, circular beam.
3 phases:
- Designation Phase: Radar is directed to general location of desired target
- Acquisition Phase: Radar system searches small volume of space in prearranged pattern until target is loaded
- Tracking Phase: Once target located, radar system automatically follows target motions

46
Q

Explain the difference between OPELINT & TECHELINT

A

OPELINT: Operationally relevant info (location, movement, tactics)
TECHELINT: Technical aspects (signal characteristics, modes, function, capabilities, vulnerabilities, & technology)

47
Q

Define Half Duplex

A

Can be used for communications in each direction, but can’t proceed simultaneously i.e. walkie-talkies

48
Q

Define Duplex

A

Allows transmission in two directions simultaneously i.e. telephone

49
Q

Define Simplex

A

Can only transfer data in a single direction i.e. broadcast radio

EIDWS (24 decks)

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