*Question G4D11:
How close to the upper edge of a band’s phone segment should your displayed carrier frequency be when using 3 kHz wide USB?*  

*Correct Answer is  B: At least 3 kHz below the edge of the band*  

### AI Response: (may contain errors)  

To determine how close to the upper edge of a band’s phone segment you should set your displayed carrier frequency when using 3 kHz wide Upper Sideband (USB), we need to consider the bandwidth of the signal and the regulations regarding frequency usage.

### Correct Answer: At least 3 kHz below the edge of the band

1. **Why the correct answer is correct:**
   - When using USB, the signal occupies a bandwidth of 3 kHz. This means that if you set your carrier frequency at the upper edge of the band, the upper side of your signal would extend 3 kHz above that frequency. 
   - To avoid interference with adjacent channels and to comply with regulations, you must ensure that your carrier frequency is at least 3 kHz below the upper edge of the band. This keeps the entire 3 kHz bandwidth of your signal within the allocated segment.

### Why the other choices are incorrect:

2. **Choice A: At least 3 kHz above the edge of the band**
   - This is incorrect because setting your frequency 3 kHz above the edge would place part of your signal outside the allocated band, leading to potential interference and violation of regulations.

3. **Choice B: At least 3 kHz below the edge of the band**
   - This choice is misleading as it does not specify the correct distance from the edge. While being below the edge is correct, it does not account for the full bandwidth of the signal.

4. **Choice C: At least 1 kHz above the edge of the segment**
   - This is incorrect because it does not provide enough separation. A 1 kHz buffer is insufficient for a 3 kHz wide signal, which could lead to interference with adjacent channels.

5. **Choice D: At least 1 kHz below the edge of the segment**
   - Similar to choice C, this does not provide adequate separation. A 1 kHz distance is not enough to ensure that the entire 3 kHz bandwidth remains within the segment.

### Summary:
- Always set your displayed carrier frequency at least 3 kHz below the upper edge of the band when using a 3 kHz wide USB signal to ensure compliance with regulations and to prevent interference with adjacent channels.