High Frequency
Satellite Communications
Radio Frequency theory
orbits / beam characteristics
100

what is the frequency range of HF?

3-30 MHz

100

what is a signal transmitted from an earth terminal TO a satellite called?

uplink

100

what is modulation?

Changing of from one state to another 

"Mixing" signals to form a new output

100

what height is a geosynchronous orbit above the equator?

22,300 miles

200

how is HF Beyond line of sight communications possible?

the signal bounces of the ionosphere to its destination 

200

what paperwork is submitted to gain access to the satellite network?

Satellite Access Request (SAR)

200

a carrier wave (carrier spike) is 

an unmodulated signal

200

What beam coverage type is used to cover 1/3 of the earth surface?

Global Beam coverage

300

what is the wavelength for 5 MHz

60 meters

300

what does IW stand for

integrated waveform

300

What is the formula to find the wavelength of a given frequency?

wavelength = velocity / frequency

wavelength = speed of light (c or 300,000 Kms) / frequency 

300

what frequency range does KU operate in?

12-18 GHz

400

What does ALE do?

automatically determines the best predetermined frequency to use

400

What does the signal to noise ratio measure 

the amount of desired signal compared to the background noise 

400

a resonant antenna is used for what?

1 specific frequency

400

geostationary orbits are above which man made imaginary line 

the equator 

500

What is a Dipole?

a dipole is center fed with 2 radiating elements

500

How is the radiation affected by the size of the reflectors.

The larger the surface area (larger the reflectors) the more narrow the beam width. (more directional)

500

describe the radiation pattern from a whip antenna

looks like a doughnut. (ratiates perpendicular to the antenna 360 degrees.

500

What imaginary lines are used to measure the position of geosynchronous satellites?

Longitude

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