Table of Contents

M-17

Overview

M-17 is an open-source digital voice protocol developed specifically for amateur radio. Unlike many proprietary digital modes, M-17 is designed to be free of licensing restrictions, encouraging innovation and widespread adoption within the amateur radio community.

M-17 operates primarily in the VHF and UHF bands and uses Frequency-Division Multiple Access (FDMA) to separate communication streams. It is optimized for voice transmission but also supports data applications. Unlike other digital modes like D-STAR, DMR, or NXDN, M-17 focuses on being fully open-source, from its protocol to its hardware implementations.

Key Features

M-17 offers several benefits for amateur radio operators:

  1. Open Source: The protocol and associated software are fully open-source, allowing developers to modify and expand functionality without restrictions.
  2. Interoperability: Designed for amateur radio, M-17 promotes seamless communication between devices using the same protocol.
  3. Efficient Bandwidth Usage: M-17 operates with a bandwidth of 9 kHz, making it spectrally efficient.
  4. Flexibility: Supports both simplex and repeater operations, as well as linking through internet gateways.

Technical Details

M-17 uses the Codec2 low-bitrate speech codec, which is also open-source. Codec2 ensures high-quality voice transmission with minimal bandwidth usage, making it suitable for both urban and remote areas.

The protocol allows for:

  1. Digital Voice Communication: Optimized for clear voice transmission.
  2. Data Transmission: Support for text messaging and other digital data types.
  3. Gateway Linking: Internet-based linking of repeaters and simplex nodes.

Encryption

As an open-source protocol, M-17 includes the ability to encrypt communications for experimental purposes. However, in the United States and other regions, the use of encryption in amateur radio is prohibited under regulations aimed at ensuring transparency in communication.

M-17 on RepeaterBook

Repeaters using the M-17 protocol can be listed on RepeaterBook. The following information is displayed on the repeater's detail page:

  1. Bandwidth (9 kHz)
  2. Associated Network, if applicable
  3. M-17 Module (for repeaters that support multiple digital modes)

RepeaterBook tracks linked M-17 systems to provide information about available nodes and repeaters.