2
1-9. When using the reference designator
1A6A4J6, what level does the number 1
refer to?
1. Subassembly
2. Assembly
3. Group
4. Unit
1-10. What is the total number of frequency
bands the military is currently using for
communications?
1. 5
2. 7
3. 9
4.
11
1-11. Extremely low-frequency transmissions
are primarily directed at which of the
following users?
1. Shore installations
2. Surface ships
3. Submarines
4. Aircraft
1-12. Vlf transmitters are used primarily for
which of the following purposes?
1. Navigation and fleet communications
2. Frequency standards and time signals
3. Astronomy and oscillator calibration
4. Aircraft control and space vehicle
tracking
1-13. Navy use of the low-frequency band is
mainly for which, if any, of the following
broadcasts?
1. Ship to shore
2. Fleet multichannel
3. Space vehicle telemetry
4. None of the above
1-14. For which of the following reasons does
the Navy use only the upper and lower
ends of the mf band?
1. They are the most reliable
2. They produce the best propagation
3. The commercial fm band occupies the
middle
4. The commercial AM band occupies
the middle
1-15. Hf communications over long-distance
trunks, or links between fixed terminals
are examples of which of the following
types of systems?
1. Fleet broadcast
2. Point-to-point
3. Ground-to-air
4. Ship-to-shore
1-16. Sending a message on several
frequencies at once is an example of
which of the following transmission
types?
1. Time-diversity
2. Phase-diversity
3. Distance-diversity
4. Frequency-diversity
1-17. What type of diversity uses physically
separated transmit or receive antennas to
improve communications?
1. Time
2. Phase
3. Space
4. Frequency
1-18. Normally the transmission range of vhf is
limited to line of sight. What technique
is used to increase this range?
1. Tropospheric scatter
2. Atmospheric diversity
3. Ionospheric maneuvering
4. Each of the above
