*Question E2E13:
Which of these digital modes has the highest data throughput under clear communication conditions?*  

*Correct Answer is  D: PACTOR IV*  

### AI Response: (may contain errors)  

To determine which digital mode has the highest data throughput under clear communication conditions, we need to consider the characteristics of each mode listed in the question.

### Correct Answer: PACTOR IV

- **Why PACTOR IV is correct:**
  - PACTOR IV is known for its high data throughput capabilities, often exceeding 1000 bits per minute (bpm) under optimal conditions. It uses advanced error correction and can adapt to varying signal conditions, allowing it to maintain high speeds even in less-than-ideal situations.

### Why the Other Choices are Incorrect:

- **A: MFSK16**
  - MFSK16 typically has a maximum throughput of around 16 to 20 characters per second, which translates to approximately 200-300 bpm. While it is efficient for certain applications, it does not match the throughput of PACTOR IV.

- **B: 170 Hz shift, 45 baud RTTY**
  - RTTY (Radio Teletype) at 45 baud has a maximum throughput of about 45 characters per minute, which is roughly 45 bpm. This is significantly lower than PACTOR IV's capabilities.

- **C: FT8**
  - FT8 is designed for weak signal communication and has a maximum throughput of about 50-100 bpm. While it is effective for its purpose, it does not achieve the high data rates that PACTOR IV can.

### Summary of Throughput:

- **Throughput Comparison:**
  - PACTOR IV: >1000 bpm
  - MFSK16: ~200-300 bpm
  - RTTY (45 baud): ~45 bpm
  - FT8: ~50-100 bpm

### Conclusion:
In summary, PACTOR IV stands out as the digital mode with the highest data throughput under clear communication conditions due to its advanced technology and error correction capabilities. The other modes, while useful in their own contexts, do not reach the same level of efficiency.