16. For convenience, the Army divides the radio communication spectrum into four bands. A radio wave
having a frequency of 250 MHz falls into the band identified as
17. The minimum requirement of a voice channel is that it must pass at least the frequencies between
a. 16 to 5,000 Hz.
b. 300 to 3,500 Hz.
c. 50 to 15,000 Hz.
d. 2,000 to 20,000 Hz.
18. When radio operators receive CW signals, they customarily adjust the receiver output tone for best ear
responsiveness. This tone frequency is approximately
a. 20 Hz.
c. 2,000 Hz.
b. 200 Hz.
d. 20,000 Hz.
19. What is the reason that audio-frequency energy cannot be radiated from an antenna of practical length?
a. Mechanical vibration of the antenna wires causes power loss.
b. Audio frequency is normally too low to provide effective radiation.
c. Sufficient power cannot be placed into the signal to enable it to radiate.
d. The signal is too easily intercepted to be useful in military applications.
20. A great deal of research and development of electronic equipment is devoted to utilization of the extended
microwave ranges. Extending the frequency spectrum through the microwave range is important because
b. more spectrum space becomes available as we go higher in frequency.
c. commercial broadcasting using the surface wave becomes more practical.
d. over-the-horizon communication becomes increasingly useful at the microwave ranges and above.
HOLD ALL TEXT MATERIALS FOR USE IN COMPLETING SUBCOURSE EXAMINATION
CHECK YOUR ANSWERS WITH LESSON #4 SOLUTION SHEET, PAGES 49 & 50.