*Question E2E02:
Which of the following synchronizes WSJT-X digital mode transmit/receive timing?*  

*Correct Answer is  B: Synchronization of computer clocks*  

### AI Response: (may contain errors)  

To understand how WSJT-X synchronizes digital mode transmit/receive timing, let's analyze the correct answer and the other options.

### Correct Answer: B - Synchronization of computer clocks

- **Explanation**: WSJT-X relies on precise timing to decode weak signals effectively. The software uses the computer's clock to synchronize the transmission and reception of signals. If the clocks of the transmitting and receiving stations are not synchronized, the timing of the digital signals can be misaligned, leading to decoding errors. Therefore, ensuring that both stations have synchronized clocks is crucial for successful communication.

### Why the Other Choices are Incorrect:

- **A: Alignment of frequency shifts**  
  - **Explanation**: While frequency shifts are important in digital modes (like in FSK), they do not directly synchronize the timing of transmit and receive operations. Frequency shifts help in distinguishing between different signals but do not address the timing aspect.

- **C: Sync-field transmission**  
  - **Explanation**: Sync-fields are used in some digital modes to indicate the start of a transmission, but they do not synchronize the clocks of the computers involved. They help in framing the data but do not ensure that both stations are operating on the same time reference.

- **D: Sync-pulse timing**  
  - **Explanation**: Sync-pulse timing refers to the timing of specific pulses used in some communication protocols. However, WSJT-X primarily relies on the synchronization of the computer clocks rather than specific sync pulses to manage timing.

### Summary

- The key to successful operation in WSJT-X is the synchronization of computer clocks, which ensures that both the transmitting and receiving stations are aligned in time, allowing for accurate decoding of signals. 

This understanding is essential for the Extra Class exam, as it highlights the importance of timing in digital communications.