The MMDVM system was created by Jonathan Naylor, G4KLX, to enable using suitable analog radios to support digital voice modes such as D-Star, DMR, P-25, Fusion and NXDN. Key to this vision was G4KLX’s creation of software to make this happen.
From DL5DI’s description: “The MMDVM is intended to be an open-source Multi-Mode Digital Voice Modem, which utilities the power of an ARM processor and a simple analogue interface board. The Multi-Mode Digital Voice Modem is a combined hardware and software development of a modem to handle all amateur digital voice modes.” The open-source software “is licensed under the GPL v2 and is intended for amateur and educational use only. Use of this software for commercial purposes is strictly forbidden.”
Andy CA6JAU has greatly extended the functionality of the original firmware and is a key contributor to the MMDVM project.
Jim McLaughlin, KI6ZUM, took G4KLX’s hardware concept and developed an early version of an MMDVM board, then continued to refine it. Others followed and did the same. KI6ZUM’s hardware design is licensed under Creative Commons – BY, NC, SA, in other words, not to be used for commercial purposes.
There are currently several legitimate sources of MMDVM boards (for example, Scott Zimmerman N3XCC), and unfortunately, there are also some knock-offs that have copied the design and are being sold for profit. We encourage Hams to avoid these types of products.
In addition, the MMDVM concept has been used to create Hotspots — that is, combining MMDVM modems with low power radio chips. The first was the ZUMspot by KI6ZUM.
Also popular is the MMDVM_HS_HAT by Florian Wolters DF2ET and Mathis Schmieder DB9MAT.