1A - HF Transceiver Equipments

Question 1

The HF band extends from _________.

Answer 1

3MHz - 30MHz

Question 2

We characterize an AM radio wave as having an _____.

Answer 2

amplitude, a frequency, and a wavelength.

Question 3

The magnitude of change in the height of the radio wave. This is the amount of power introduced to the signal.

Answer 3

Amplitude

Question 4

The number of cycles completed by a periodic quantity in a unit of time. The number of cycles per second (1/Frequency).

Answer 4

Frequency

Question 5

The distance over which the wave’s shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests or
troughs.

Answer 5

Wavelength

Question 6

Frequency and wavelength have an ____ relationship.

Answer 6

inverse

Question 7

The symbol for wavelength is Greek letter ____.Wavelength = ____________. Wavelength is measured in ____.

Answer 7

lambda (λ)
the speed of light divided by the frequency of the signal
meters

Question 8

How radio waves move in free space and over the surface of
the earth is called:

Answer 8

Radio wave propagation

Question 9

____ travel at or near the earth’s surface.

Answer 9

Ground waves

Question 10

This refers to radio waves that travel in a straight line from the transmitting
antenna to the receiving antenna.

Answer 10

Line of Sight (LOS)

Question 11

____ is the only method of propagation possible at frequencies above 30MHz.

Answer 11

LOS

Question 12

On the surface of the earth, LOS propagation is limited by the visual horizon to about _____.

Answer 12

64 km (40 miles)

Question 13

The ____ layers are all responsible for HF long haul communications, but the _ layer allows communications to take place beyond an estimated 1,500 miles.

Answer 13

D, E, and F
F

Question 14

____ combines two or more frequencies (i.e., the RF carrier wave & the user data/intelligence wave) across a
nonlinear device to produce new frequencies.

Answer 14

Heterodyning

Question 15

The sum frequency is also known as the ___.

Answer 15

upper sideband (USB)

Question 16

The difference frequency is also known as the ___.

Answer 16

lower sideband (LSB)

Question 17

The modulated carrier wave is also known as the ___.

Answer 17

composite signal

Question 18

Another aspect of AM is that ____ are transmitted even though they contain the same information.

Answer 18

both the sidebands

Question 19

The carrier consumes ___ of the total power produced while the sidebands take up ___.

Answer 19

two thirds
the other third

Question 20

These sidebands occupy from ____ (first 300Hz is filtered out because it is considered noise) to a maximum of ___ on each side of the center frequency for a maximum total bandwidth of ___.

Answer 20

300Hz
3,000Hz
6000Hz (6kHz)

Question 21

Single Side Band is a variant of AM that uses transmitter power and bandwidth more efficiently by ____.

Answer 21

suppressing the carrier and eliminating one of the sidebands.

Question 22

_____ refers to decreasing the bandwidth of each channel in a radio system. This creates more channels in the overall radio spectrum (in our case HF).

Answer 22

Spectrum conservation

Question 23

Two aspects of power efficiency:

Answer 23

• Available power is concentrated in the one utilized sideband.
• Power output is only developed when carrier is modulated with intelligence (data or voice).

Question 24

The bandwidth of a SSB receiver is ___ the bandwidth of an AM receiver to receive the same signal.

Answer 24

less than half

Question 25

The transmitter’s averaged power output during one RF cycle (a sample) at the highest crest of the modulation envelope.

Answer 25

Peak Envelope Power (PEP)

Question 26

Modulation only occurs when ____.

Answer 26

there is intelligence that needs to be applied to the signal

Question 27

We generally use the manpack radio for short-range/groundwave transmissions in the ____ maximum range.

Answer 27

20-watt

Question 28

We generally use the manpack radio for ____ transmissions in the 20-watt maximum range.

Answer 28

short-range/groundwave

Question 29

The ____ is the most advanced military Type-1 encryption HF radio available today, setting the standard for reliable, long-range HF communication on the battlefield.

Answer 29

AN/PRC-160