*Question E2A07:
Which of the following types of signals can be relayed through a linear transponder?*  

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

### AI Response: (may contain errors)  

A linear transponder is a type of repeater that receives a range of frequencies and retransmits them on a different range of frequencies. It is capable of handling multiple types of signals simultaneously, as long as they fall within its passband. Let's break down the options:

1. **Why the correct answer is correct:**

   - **D: All these choices are correct**  
     A linear transponder can relay any type of signal that fits within its bandwidth. This includes:
     - **FM (Frequency Modulation)**: A method of encoding information in a carrier wave by varying the frequency.
     - **CW (Continuous Wave)**: A simple form of radio communication using Morse code.
     - **SSB (Single Sideband)**: A form of amplitude modulation that uses less bandwidth and power.
     - **SSTV (Slow Scan Television)**: A method of transmitting still images over radio.
     - **PSK (Phase Shift Keying)**: A digital modulation scheme that conveys data by changing the phase of a reference signal.
     - **Packet**: A form of digital communication that breaks data into packets for transmission.

   Since a linear transponder can handle all these types of signals, option D is correct.

2. **Why the other choices are incorrect:**

   - **A: FM and CW**  
     While FM and CW can be relayed through a linear transponder, this choice is incomplete because it does not include all the possible signal types that can be relayed.

   - **B: SSB and SSTV**  
     Similar to choice A, SSB and SSTV can be relayed, but this choice is also incomplete.

   - **C: PSK and packet**  
     Again, PSK and packet can be relayed, but this choice does not encompass all the signal types that a linear transponder can handle.

3. **Useful rules of thumb:**

   - A linear transponder is versatile and can handle any signal type that fits within its bandwidth.
   - The key limitation is the bandwidth of the transponder, not the modulation type of the signal.

In summary, a linear transponder can relay a wide variety of signal types, making option D the correct choice.