*Question E2D04:
What technology is used for real-time tracking of balloons carrying amateur radio transmitters?*  

*Correct Answer is  C: APRS*  

### AI Response: (may contain errors)  

APRS (Automatic Packet Reporting System) is the correct answer for real-time tracking of balloons carrying amateur radio transmitters. Here's why:

1. **Why the correct answer is correct:**
   - **APRS**: This system is specifically designed for real-time communication of information such as location, weather, and messages. It uses packet radio to transmit data, which is ideal for tracking moving objects like balloons. APRS can send GPS coordinates and other telemetry data, making it perfect for this application.

2. **Why the other choices are incorrect:**
   - **FT8**: This is a digital mode used primarily for weak signal communication on HF bands. It is not designed for real-time tracking or transmitting location data.
   - **Bandwidth compressed LORAN**: LORAN (Long Range Navigation) is a terrestrial navigation system that was used for determining position. It is not used in amateur radio for tracking purposes and is not related to real-time data transmission.
   - **PACTOR III**: This is a digital mode used for sending data over HF bands, often for email and file transfers. It is not designed for real-time tracking or telemetry.

3. **Useful Information:**
   - APRS uses a network of amateur radio stations to relay data packets, which can include GPS coordinates, allowing for real-time tracking of objects like balloons.
   - The system can be accessed via radio or the internet, providing flexibility in how data is transmitted and received.

In summary, APRS is the technology specifically designed for real-time tracking and telemetry, making it the correct choice for this application.