*Question G8A06:
Which of the following is characteristic of QPSK31?*  

*Correct Answer is  D: All these choices are correct*  

### AI Response: (may contain errors)  

QPSK31, or Quadrature Phase Shift Keying 31, is a digital mode used in amateur radio that has several key characteristics. Let's break down the question and the answer choices.

### Correct Answer: D - All these choices are correct

1. **Why the correct answer is correct:**
   - **Sideband Sensitivity:** QPSK31 is indeed sideband sensitive, meaning it requires a specific sideband (USB or LSB) for proper operation.
   - **Error Correction:** QPSK31 uses a form of encoding that provides some level of error correction, which helps in maintaining the integrity of the transmitted data.
   - **Bandwidth:** The bandwidth of QPSK31 is approximately the same as BPSK31 (Binary Phase Shift Keying 31), which is about 31 Hz. This is because both modes are designed to operate within similar bandwidth constraints.

### Why the other choices are incorrect:
- **A: It is sideband sensitive:** This statement is true, but it is only one part of the overall characteristics of QPSK31.
- **B: Its encoding provides error correction:** This statement is also true, but again, it does not encompass the full range of characteristics.
- **C: Its bandwidth is approximately the same as BPSK31:** This statement is true as well, but it is just one aspect of QPSK31.

Since all individual statements (A, B, and C) are true, the most comprehensive answer is D, which encompasses all the characteristics.

### Summary:
- QPSK31 is sideband sensitive, provides error correction, and has a bandwidth similar to BPSK31.
- Therefore, the correct answer is D: All these choices are correct. 

This understanding will help you recognize the features of QPSK31 and similar digital modes in the Extra Class exam.