*Question E1F01:
[97.305] On what frequencies are spread spectrum transmissions permitted?*  

*Correct Answer is  B: Only on amateur frequencies above 222 MHz*  

### AI Response: (may contain errors)  

Spread spectrum transmissions are a type of communication technique that spreads the signal over a wide frequency band, making it more resistant to interference and eavesdropping. The FCC has specific rules about where these transmissions are allowed in the amateur radio bands.

1. **Correct Answer: B - Only on amateur frequencies above 222 MHz**

   - The FCC rules, specifically 47 CFR §97.305, permit spread spectrum transmissions on amateur frequencies above 222 MHz. This means that any frequency allocation for amateur radio that is higher than 222 MHz can be used for spread spectrum.

2. **Why the other choices are incorrect:**

   - **Choice A: Only on amateur frequencies above 50 MHz**
     - This is incorrect because the FCC does not allow spread spectrum transmissions on all frequencies above 50 MHz. The rule specifically starts at frequencies above 222 MHz.

   - **Choice C: Only on amateur frequencies above 420 MHz**
     - This is incorrect because it is too restrictive. Spread spectrum is allowed on frequencies above 222 MHz, not just those above 420 MHz.

   - **Choice D: Only on amateur frequencies above 144 MHz**
     - This is incorrect because, while 144 MHz is a common amateur band, spread spectrum is not permitted until frequencies above 222 MHz.

3. **Useful Rule of Thumb:**

   - Remember that spread spectrum is allowed on higher frequency bands, starting just above the 222 MHz band. This is a key point to remember for the exam and practical application in amateur radio operations.