Question
On what frequencies are spread spectrum transmissions permitted?
Answer Options
- A) Only on amateur frequencies above 50 MHz
- B) Only on amateur frequencies above 222 MHz
- C) Only on amateur frequencies above 420 MHz
- D) Only on amateur frequencies above 144 MHz
Correct Answer: B
Explanation
Spread spectrum (SS) is a modulation technique that intentionally spreads the signal’s energy across a very wide bandwidth, making it highly resistant to interference and difficult to intercept. Due to its wide bandwidth and shared spectrum concerns, the FCC places strict limits on where amateur stations may use spread spectrum techniques.
Specifically, amateur use of spread spectrum transmissions is permitted only on amateur frequencies above 222 MHz. This limits the activity to the UHF and microwave bands (such as 1.25 meters, 70 centimeters, 33 centimeters, 23 centimeters, etc.). The higher frequency ranges offer broader contiguous segments, which are necessary for the wide bandwidth characteristic of spread spectrum operation, minimizing interference to narrowband modes.
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