*Question E8C10:
How can data rate be increased without increasing bandwidth?*  

*Correct Answer is  C: Using a more efficient digital code*  

### AI Response: (may contain errors)  

To increase data rate without increasing bandwidth, you can use a more efficient digital code. Here's why:

1. **Correct Answer: Using a more efficient digital code (Choice C)**
   - A more efficient digital code can transmit the same amount of information using fewer bits. This means you can send more data in the same amount of time without needing additional bandwidth. Techniques like data compression or more advanced modulation schemes (e.g., QAM) can achieve this.

2. **Why the other choices are incorrect:**
   - **Choice A: It is impossible**
     - This is incorrect because it is indeed possible to increase data rate without increasing bandwidth by optimizing how data is encoded and transmitted.
   - **Choice B: Increasing analog-to-digital conversion resolution**
     - Increasing the resolution of analog-to-digital conversion means using more bits to represent each sample, which actually increases the amount of data to be transmitted, potentially requiring more bandwidth.
   - **Choice D: Using forward error correction**
     - Forward error correction (FEC) adds extra bits to the data stream to allow error detection and correction. While it improves reliability, it typically increases the amount of data to be transmitted, which can require more bandwidth.

In summary, using a more efficient digital code allows for a higher data rate within the same bandwidth by optimizing the way data is represented and transmitted.