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MMDVM
Oct 15, 2015 18:17:24 GMT -8
Post by N6HKH on Oct 15, 2015 18:17:24 GMT -8
The MMDVM
Sep 9 2015 naylorjs
The Multi-Mode Digital Voice Modem is a combined hardware and software development of a modem to handle all amateur digital voice modes. Initially it will support D-Star and DMR, with System Fusion and P.25 coming later, as well as a built-in FM repeater controller. For all modes other than DMR and FM, the modem can be used in simplex or duplex mode, while for DMR and FM full duplex must be used. The protocol between the modem and the host is new.
The hardware will typically be ARM based, with initial developments being aimed at the Arduino Due and Teensy 3.1, the STM32 range is also looking like a suitable chip, with the more advanced Cortex M4 architecture and higher clock speeds. The interfacing hardware will consist of op-amp low pass filters and level shifters.
There are no time scales for the release of hardware or software as all development is done in my spare time and there is a lot to do.
If you have any experience of ARM (or any other decent embedded CPU), you are welcome to take part.
Jonathan G4KLX
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MMDVM
Oct 15, 2015 18:19:44 GMT -8
Post by N6HKH on Oct 15, 2015 18:19:44 GMT -8
History of the MMDVM
Sep 15, 2015 naylorjs
The idea of the MMDVM originally came from another idea. On my long commute to work, I would go past D-Star, DMR and FM repeaters on 2m and 70cms. In fact there is a 2m Fusion repeater opening up along the route so that should be included too. I had an idea to create a unit, with a Raspberry Pi at its heart, a DV3000 or DV3000U, a simple display, some push buttons connected to the GPIO pins and something like a FunCube Pro+ for the receiver. Something like that would be able to decode almost any non-voice mode that I wanted to. The channels and callsigns, frequencies and modes would have been read from a config file, and the buttons would allow me to cycle through them. I only wanted to be able to monitor, not transmit. I avoid the long commute now by staying in cheap lodgings close to work during the week and going home at weekends. What moved the idea along was the existence of the DV-RPTR series and an article in RadCom about using an Arduino Due to sample audio from a receiver and to display the spectrum, using an FFT, on an attached display. M0XPD has a blog about using an Arduino Due as an audio filter, and people have mentioned the Teensy and STM32 systems to me.
I may go back to my original idea one day, but for now the MMDVM takes my time. Now back to drilling holes and writing code. Jonathan G4KLX
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