*Question E2B08:
What technique allows commercial analog TV receivers to be used for fast-scan TV operations on the 70-centimeter band?*  

*Correct Answer is  A: Transmitting on channels shared with cable TV*  

### AI Response: (may contain errors)  

To understand why commercial analog TV receivers can be used for fast-scan TV (FSTV) operations on the 70-centimeter band, let's look at the correct answer and the other options:

### Correct Answer: Transmitting on channels shared with cable TV

- **Explanation**:  
  Commercial analog TV receivers are designed to receive signals on specific frequencies. Some of these frequencies overlap with the 70-centimeter amateur radio band (420-450 MHz). Cable TV channels, particularly those in the UHF range, can share these frequencies. By transmitting on these shared channels, amateur radio operators can use standard TV receivers to view FSTV signals without needing specialized equipment.

### Why the Other Choices are Incorrect:

- **Choice B: Using converted satellite TV dishes**  
  - **Explanation**:  
    Satellite TV dishes are used for receiving signals from satellites, typically in the GHz range, which is much higher than the 70-centimeter band. They are not directly related to the frequency compatibility needed for using commercial TV receivers for FSTV.

- **Choice C: Transmitting on the abandoned TV channel 2**  
  - **Explanation**:  
    TV channel 2 is in the VHF band (54-60 MHz), which does not overlap with the 70-centimeter band. Therefore, transmitting on channel 2 would not allow the use of commercial TV receivers for FSTV on the 70-centimeter band.

- **Choice D: Using USB and demodulating the signal with a computer sound card**  
  - **Explanation**:  
    This choice refers to using a computer to process signals, which is not related to using commercial analog TV receivers. USB (Upper Sideband) is a mode of transmission, and while sound cards can demodulate certain signals, this does not involve using standard TV receivers for FSTV.

### Summary

The key to using commercial analog TV receivers for FSTV on the 70-centimeter band is the frequency overlap with cable TV channels. This allows the receivers to pick up the transmitted signals without additional modifications.