SM1000 FreeDV adapter

sm1000 freedv

The SM1000 allows you to run FreeDV without a PC on any radio. Just plug it into your SSB or FM radio, and you now have Digital Voice (DV).

You don’t have to buy a new radio to run Digital Voice! It’s based on a STM32F4 micro-controller, has a built in microphone, speaker amplifier, speaker, and transformer isolated interfaces to your radio. It’s just 80 x 100mm, and can be held in you hand and used like a regular PTT microphone. Or it can sit on your bench and work with your favourite headset.

Was developed by David Rowe VK5DGR and Rick Barnich KA8BMA. It is being manufactured, tested and shipped by our good friend Edwin at Dragino in Shenzhen, China.

The SM1000 is completely open – hardware and software – including the Codec 2 vocoder. You are encouraged to modify the software and hardware. It is possible to reprogram the SM1000 for other applications, such as speech processing for SSB radio using open source gcc tools.

The rig audio and PTT connections are 3.5mm audio sockets in parallel with a RJ45. A small patch panel can be used to configure the RJ45 pin out for your radio. You need to supply audio cables, e.g. 3.5mm or RJ45 to your radio.

Operates from 8-16V (12V nominal) and uses approximately 200mW. Perfect for mobile or SOTA work! It also has a USB port to support reflashing from a Windows or Linux PC.

The initial firmware load will be a “FreeDV 1600” compatible mode. Later in 2015 enhanced (low SNR) HF and VHF FreeDV modes will be released.

Supports “analog pass through” so you can make SSB contacts without having to swap microphones. Press the mode button and it’s DV, one more press and you’re back to SSB. It’s easy to setup – a LED indicates microphone level clipping on transmit and errors on receive. Levels (to and from your radio and mic gain) are set using trimpots.

SM1000 is supplied in a sturdy metal enclosure, with a USB programming cable, and jumper wires for the RJ45 patch panel. You need to supply a 2.5mm plug centre positive 12VDC (nominal) power source, and patch cables to connect to your radio. 


SM1000 FreeDV adapter Specifications

Parameter Value
Modes Analog, FreeDV 1600, FreeDV 700D
DC Power Input CN3 8-15VDC, 200mW max
Rig Mic Output CN7 0.5 to 50mVpp
Ext Mic Input CN5 1000 (Jumper J3 in place) or 2000 (Jumper J3 removed) ohms AC impedance
Rig PTT Output CN9 Floating, less than 100 ohms on resistance
Ext Speaker Output 4 ohms min, 700mW max power into 8 ohms with 12V power input voltage



Source Code


SM1000 Manual

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