*Question E2A02:
Which of the following is characteristic of an inverting linear transponder?*  

*Correct Answer is  D: All these choices are correct*  

### AI Response: (may contain errors)  

An inverting linear transponder is a type of satellite transponder that reverses the frequency characteristics of the signal it receives. Let's break down why each choice is correct:

1. **Doppler Shift**:  
   - **Explanation**: Doppler shift occurs when there is relative motion between the satellite and the ground station, causing a frequency shift in the received signal. In an inverting transponder, the uplink and downlink Doppler shifts are in opposite directions. This can help reduce the overall perceived Doppler shift on the ground.
   - **Choice A**: This is correct because the inverting nature of the transponder causes the uplink and downlink Doppler shifts to counteract each other.

2. **Signal Position Reversal**:  
   - **Explanation**: An inverting transponder reverses the frequency spectrum of the signal. If a signal is transmitted at a lower frequency on the uplink, it will appear at a higher frequency on the downlink, and vice versa.
   - **Choice B**: This is correct because the signal's position in the frequency band is reversed due to the inversion process.

3. **Sideband Inversion**:  
   - **Explanation**: In an inverting transponder, the modulation sidebands are also inverted. This means that an upper sideband (USB) signal on the uplink will become a lower sideband (LSB) signal on the downlink, and vice versa.
   - **Choice C**: This is correct because the transponder inverts the sidebands, changing USB to LSB and LSB to USB.

Since all these characteristics are true for an inverting linear transponder, the correct answer is **D: All these choices are correct**. Each individual choice describes a valid characteristic of an inverting linear transponder, making them all correct.