*Question E2E05:
Which of these digital modes does not support keyboard-to-keyboard operation?*  

*Correct Answer is  A: WSPR*  

### AI Response: (may contain errors)  

WSPR (Weak Signal Propagation Reporter) is the correct answer because it is not designed for keyboard-to-keyboard communication. Here's why:

1. **Why WSPR is Correct:**
   - **WSPR** is a digital mode used primarily for propagation studies. It automatically transmits and receives low-power signals to analyze how radio waves propagate over long distances. It is not intended for real-time, interactive communication between operators, which is characteristic of keyboard-to-keyboard modes.

2. **Why the Other Choices are Incorrect:**
   - **RTTY (Radio Teletype):** This is a classic digital mode that supports keyboard-to-keyboard operation. Operators can type messages in real-time, which are then transmitted as a series of tones.
   - **PSK31 (Phase Shift Keying, 31 baud):** This mode is specifically designed for real-time keyboard-to-keyboard communication. It is efficient and allows for low-power operation, making it popular among amateur radio operators.
   - **MFSK16 (Multiple Frequency Shift Keying, 16 tones):** This mode also supports keyboard-to-keyboard communication. It uses multiple tones to encode data, allowing for robust communication even in poor conditions.

In summary, WSPR is used for automated signal reporting and propagation analysis, not for direct communication between operators, which is why it does not support keyboard-to-keyboard operation. The other modes (RTTY, PSK31, MFSK16) are all designed for real-time, interactive communication.