*Question E2D01:
Which of the following digital modes is designed for meteor scatter communications?*  

*Correct Answer is  B: MSK144*  

### AI Response: (may contain errors)  

MSK144 is the correct answer for digital modes designed for meteor scatter communications. Here's why:

1. **Why MSK144 is Correct:**
   - **MSK144**: This mode is specifically designed for meteor scatter communications. It uses a fast transmission rate to take advantage of the brief signal reflections off meteor trails. The mode is optimized for the short bursts of signal that occur during meteor scatter events.

2. **Why the Other Choices are Incorrect:**
   - **WSPR (Weak Signal Propagation Reporter)**: This mode is used for weak signal communication and propagation studies, not specifically for meteor scatter. It is designed to work with very low power levels over long distances.
   - **Hellschreiber**: This is a facsimile-based mode that transmits text as a series of dots, similar to a fax machine. It is not optimized for meteor scatter, which requires rapid data transmission.
   - **APRS (Automatic Packet Reporting System)**: This mode is used for real-time communication of information such as location and weather data. It is not designed for meteor scatter communications.

3. **Useful Information:**
   - Meteor scatter communication relies on the brief ionized trails left by meteors entering the Earth's atmosphere. These trails can reflect radio waves, allowing for communication over distances typically ranging from 500 to 1500 kilometers.
   - MSK144 is part of the WSJT-X suite of digital modes, which are designed for weak-signal communication. It uses a modulation technique called Minimum Shift Keying (MSK) to efficiently transmit data during the short windows of opportunity provided by meteor scatter.