113: Technical Fundamentals

Question 1

113.1
Define each band of the electromagnetic spectrum and describe what signals are commonly associated with each

Answer 1

EHF: Extremely High Frequency- 30GHZ to 300GHZ
SHF: Super High Frequency- 3GHZ to 30GHZ
UHF: Ultra High Frequency- 300MHZ to 3 GHZ
VHF: Very High Frequency- 30MHZ to 300MHZ
HF: High Frequency- 3MHZ to 30MHZ
MF: Medium Frequency- 300KHZ to 3MHZ
LF: Low Frequency- 30KHZ to 300KHZ
VLF: Very Low Frequency- 3 KHZ to 30KHZ
ELF: Extremely Low Frequency- 3Hz to 30Hz

Question 2

113.2a
Describe the communication capabilities in EHF

Answer 2

Protected band; Secure Voice and DATA SATCOM, IP Services

Question 3

113.2b
Describe the communication capabilities in SHF

Answer 3

Wideband; high bandwidth data SATCOM, IP Services (DoDWB)

Question 4

113.2c
Describe the communication capabilities in UHF

Answer 4

Narrowband; LOS and SATCOM voice and data services

Question 5

113.2d
Describe the communication capabilities in VHF

Answer 5

LOS voice comms, FM radio

Question 6

113.2e
Describe the communication capabilities in HF

Answer 6

around since WW1; long distance transmission of HF signals dependent on refraction

Question 7

113.2f
Describe the communication capabilities in MF

Answer 7

international distress frequencies; FM radio

Question 8

113.2g
Describe the communication capabilities in LF

Answer 8

used for comms since radio invention; bothered by atmospheric noise

Question 9

113.2h
Describe the communication capabilities in VLF

Answer 9

sub comms

Question 10

113.2i
Describe the communication capabilities in ELF

Answer 10

sub comms except for USA since 2004

Question 11

113.3a
Define and discuss Frequency

Answer 11

measured in Hz; cycles per second

Question 12

113.3b
Define and discuss Wavelength

Answer 12

distance in space occupied by one radio wave cycle of a at any given instant

Question 13

113.3c
Define and discuss Ducting

Answer 13

Trapping of an RF wave between two layers of the earth’s atmosphere or between an atmospheric layer and the earth

Question 14

113.3d
Define and discuss Refraction

Answer 14

change in the direction of the wave when it passes through a different medium

Question 15

113.3e
Define and discuss Multiplexing

Answer 15

simultaneous transmission of two or more signals over a common carrier wave

Question 16

113.3f
Define and discuss Bandwidth

Answer 16

difference between the upper frequency limit and the lower frequency limit

Question 17

113.3g
Define and discuss Keying

Answer 17

Initiates the process of transmitting

Question 18

113.3h
Define and discuss Azimuth and Elevation Angle

Answer 18

Azimuth Angle: 360 degree angle at which the radio wave travels
Elevation Angle: angle at which the radio wave travels from the antenna to the atmosphere

Question 19

113.4a
Discuss/describe the Troposphere and how it affects communications

Answer 19

high moisture concentrations; either a signal is attenuated and passed or ducting occurs

Question 20

113.4b
Discuss/describe the Stratosphere and how it affects communications

Answer 20

constant temp; little to no effect on radio waves

Question 21

113.4c
Discuss/describe the Ionosphere and how it affects communications

Answer 21

interaction of highly charged particles allows more successful long distance communications

Question 22

113.5a
Discuss frequency and give a description of what it means in relation to the atmosphere

Answer 22

cycles per second; specific frequencies will reflect/refract off the atmosphere allowing comms without satellites

Question 23

113.5b
Discuss Radio waves and give a description of what it means in relation to the atmosphere

Answer 23

keyed electromagnetic patterns that enable comms at long distances by bouncing signals off the atmosphere

Question 24

113.5c
Discuss propagation paths and give a description of what it means in relation to the atmosphere

Answer 24

path a signal takes from the transmitter to the receiver including any changes caused by passing through the atmosphere

Question 25

113.6a Describe the USB modulation type and its usage

Answer 25

Upper Sideband; all sum frequencies above the carrier wave

Question 26

113.6b Describe the LSB modulation type and its usage

Answer 26

Lower Sideband; all difference frequencies below the carrier wave

Question 27

113.6c Describe the CW modulation type and its usage

Answer 27

continuous wave; electromagnetic wave of constand amplitude and frequency

Question 28

113.6d Describe the AM modulation type and its usage

Answer 28

amplitude modulation; modulating an electromagnetic carrier frequency by varying its amplitude IAW the message intelligence that is to be transmitted

Question 29

113.6e Describe the FM modulation type and its usage

Answer 29

frequency modulation; conveys information on a carrier wave by varying its frequency

Question 30

113.7a Define PRI/PRT as it applies to RADAR

Answer 30

Pulse Repetition Interval/Time - time or duration between the start of one pulse and the start of the next pulse *reciprocal of PRF

Question 31

113.7b Define PRF as it applies to RADAR

Answer 31

Pulse Repetition Frequency - number of pulses transmitted by a radar each second *reciprocal of PRI/PRT

Question 32

113.7c Define RF as it applies to RADAR

Answer 32

Radio Frequency any frequency or electromagnetic energy capable of propagation into space

Question 33

113.7d Define BW as it applies to RADAR

Answer 33

bandwidth section of the frequency spectrum that specific signals occupy

Question 34

113.7e Define CW as it applies to RADAR

Answer 34

continuous wave an electromagnetic wave of constant amplitude and frequency

Question 35

113.7f Define PW as it applies to RADAR

Answer 35

pulse width time between the leading and trailing edges of a pulse

Question 36

113.7g Define scan as it applies to RADAR

Answer 36

time it takes an rf beam to complete one search cycle of the scan pattern

Question 37

113.8a Define Half Duplex

Answer 37

push2talk; one way flow of information between terminals; flow in either direction but not simultaneously

Question 38

113.8b Define full Duplex

Answer 38

cell phone; telecommunications between stations happen simultaneously in both directions using two separate frequencies

Question 39

113.8c Define semi Duplex

Answer 39

push2talk on one side, cell phone on the other side; communication is dual-simplex on one side and full duplex on the other side

Question 40

113.8d Define simplex

Answer 40

walkie talkie; uses a single channel or frequency to exchange information between 2 or more terminals; one direction only

Question 41

113.8e Define broadcast

Answer 41

TV, Radio; allowing the transmission of signals in all directions with units receiving simultaneously

Question 42

113.9 Describe modulation and demodulation for signals analysis

Answer 42

modulation - process of varying one or more properties of a periodic waveform (carrier signal) by overlaying a data signal to make a new data signal; Am/FM radio are examples demodulation - process of reversing modulation; goal is to extract the data from the analog signal

Question 43

113.10 Describe bearing resolution, azimuth, and elevation angle in regards to RADAR function

Answer 43

the resolution of each of these terms is a radar system's ability to separate objects at the same range