*Question E2E07:
How does Q65 differ from JT65?*  

*Correct Answer is  C: Multiple receive cycles are averaged*  

### AI Response: (may contain errors)  

To understand the differences between Q65 and JT65, let's break down the question and the answer choices.

### Correct Answer: C - Multiple receive cycles are averaged

- **Explanation**: Q65 is designed to improve the performance of weak signal communication by averaging multiple receive cycles. This means that Q65 can take several instances of received data and combine them to enhance the overall signal quality and reliability. This averaging process helps in decoding signals that might be too weak to decode in a single pass.

### Why the Other Choices are Incorrect:

- **A: Keyboard-to-keyboard operation is supported**  
  - **Explanation**: This statement is not true for Q65. Q65 is primarily a digital mode focused on weak signal communication, similar to JT65, but it does not support real-time keyboard-to-keyboard operation like some other modes (e.g., PSK31). Instead, it is designed for structured message exchanges.

- **B: Quadrature modulation is used**  
  - **Explanation**: While both Q65 and JT65 use digital modulation techniques, Q65 does not specifically utilize quadrature modulation. Instead, it employs a different method optimized for weak signal performance. JT65 uses a form of frequency-shift keying (FSK) rather than quadrature modulation.

- **D: All these choices are correct**  
  - **Explanation**: Since both A and B are incorrect, this choice cannot be correct. For an answer to be "all correct," all individual statements must be true, which they are not in this case.

### Summary

- Q65 improves weak signal communication by averaging multiple receive cycles.
- It does not support keyboard-to-keyboard operation and does not specifically use quadrature modulation.

This understanding will help you differentiate between Q65 and JT65 effectively for the exam.