*Question T8C09:
Which of the following protocols enables an amateur station to transmit through a repeater without using a radio to initiate the transmission?*  

*Correct Answer is  D: EchoLink*  

### AI Response: (may contain errors)  

To understand why EchoLink is the correct answer for transmitting through a repeater without using a radio, let's break down each option:

### Correct Answer: EchoLink
- **EchoLink** allows users to connect to a repeater via the internet. This means that a user can initiate a transmission from a computer or smartphone using the EchoLink software, without needing a physical radio to start the communication. The connection is made over the internet, and the repeater then transmits the audio.

### Why the Other Choices are Incorrect:
- **A: IRLP (Internet Radio Linking Project)**
  - IRLP also allows linking via the internet, but it typically requires a radio to initiate the connection to the repeater. Users must use a radio to access the IRLP node, making it not suitable for the question's requirement.

- **B: D-STAR**
  - D-STAR is a digital voice and data protocol that allows for internet linking, but it still requires a D-STAR radio to initiate the transmission. Users must have a compatible radio to connect to D-STAR repeaters.

- **C: DMR (Digital Mobile Radio)**
  - DMR is a digital radio protocol that allows for talk groups and can be linked via the internet, but like D-STAR, it requires a DMR-capable radio to initiate the communication. Users cannot start a DMR transmission without a radio.

### Summary
- **EchoLink** is unique in that it allows for initiation of communication without a radio, using internet-based software instead.
- The other options (IRLP, D-STAR, DMR) all require a physical radio to start the transmission.

This distinction is crucial for understanding how different protocols operate in the amateur radio realm, especially in the context of using repeaters.