*Question T8D07:
Which of the following describes DMR?*  

*Correct Answer is  A: A technique for time-multiplexing two digital voice signals on a single 12.5 kHz repeater channel*  

### AI Response: (may contain errors)  

To understand the correct answer for the question about DMR (Digital Mobile Radio), let's break down the options:

### Correct Answer: 
**A: A technique for time-multiplexing two digital voice signals on a single 12.5 kHz repeater channel.**

- **Explanation**: DMR is a digital radio standard that allows two separate voice conversations to occur on the same frequency channel by using time division multiplexing (TDM). This means that the channel is divided into time slots, allowing for efficient use of the 12.5 kHz bandwidth. Each conversation is assigned a specific time slot, enabling simultaneous communication without interference.

### Why the Other Choices are Incorrect:

- **B: An automatic position tracking mode for FM mobiles communicating through repeaters.**
  - **Explanation**: This describes Automatic Packet Reporting System (APRS), which is used for position tracking and not specifically related to DMR. DMR focuses on voice communication rather than position tracking.

- **C: An automatic computer logging technique for hands-off logging when communicating while operating a vehicle.**
  - **Explanation**: This option refers to logging software or systems that may assist in keeping track of contacts, but it does not describe DMR. DMR is primarily about voice communication and does not inherently include logging features.

- **D: A digital technique for transmitting on two repeater inputs simultaneously for automatic error correction.**
  - **Explanation**: This option suggests a method of error correction that is not a characteristic of DMR. DMR does not transmit on two inputs simultaneously; rather, it uses time slots on a single channel for efficient communication.

### Summary:
- DMR is specifically designed for efficient voice communication using time-multiplexing on a single channel.
- The other options describe different technologies or functionalities that do not align with the core purpose of DMR.

### Useful Concepts:
- **Time Division Multiplexing (TDM)**: A method that divides a channel into time slots, allowing multiple signals to share the same frequency without interference.
- **Bandwidth Efficiency**: DMR allows two voice channels to operate within the narrow 12.5 kHz bandwidth, making it a highly efficient digital communication method. 

Understanding these concepts will help you grasp the functionality of DMR and differentiate it from other communication technologies.