HF in the Digital Age

Question 1

HF CAN BE USED FOR?

Answer 1

• Line of Sight
• Ground (Surface) Wave
• NVIS
• Long Range Comms

Question 2

CHARACTERISTICS OF A RADIO WAVE?

Answer 2

• Amplitude
• Frequency
• Wavelength

Question 3

WAVELENGTH @ 10MHz?

Answer 3

30m

Question 4

AM?

Answer 4

Input signal’s amplitude is superimposed onto the CW

- Inefficient use of power

Question 5

FM?

Answer 5

Input signal’s frequency is superimposed onto the CW

- Clearer signal / Uses more bandwidth

Question 6

SSB (USB / LSB)?

Answer 6

Only tx one side-band by suppressing the CW and the other side-band

• More efficient use of power
• Uses half the bandwidth of AM

Question 7

GROUND WAVES?

Answer 7

• Direct Waves
• Ground (Surface) Waves
• Ground-Reflected Waves

Question 8

SKY WAVES?

Answer 8

Those waves which refract off the ionosphere

- effected by: freq, TOD, atmospheric conditions etc

Question 9

WHAT IS MODULATION?

Answer 9

The process where the phase, amplitude or frequency of the CW is modified to convey intelligence

Question 10

THE IONOSPHERE?

Answer 10

Region of electrically charged particles or gases in the earths atmosphere, extending from 50-600km above the earths surface

Question 11

IONISATION?

Answer 11

Caused by solar radiation, the process of electrically charging particles

Question 12

AE IMPEDANCE?

Answer 12

The load applied to the transmitter

- Depends upon antenna type, freq, surrounds etc

Question 13

AE GAIN?

Answer 13

The ability of an AE to focus energy in a particular direction