For the last few months Rick Barnich KA8BMA and I have been working on the SM1000, a embedded hardware product that allows you to run FreeDV without a PC. Just plug it into your SSB or FM radio, and you now have Digital Voice (DV). It’s based on a STM32F4 micro-controller, has a built in microphone, speaker amplifier, 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 sit near your radio in a small box form factor. The SM1000 will be in production later in 2014 and will retail for US$195.
Here is a block diagram of the SM1000 (click for larger version):
The whole design is open hardware (TAPR license). It will run an embedded version of FreeDV which is also 100% open source. You can forget about proprietary, expensive DV modes from other vendors that force you to use their hardware and make it illegal for you to experiment. Open source is the future of Digital Voice.
The SM1000 has a RJ45 and 3.5mm sockets to interface to your radio, including a little patch panel to configure the RJ45 wiring. As it’s hand held and operates from 6-12V it could even run with low cost FM HTs, as an external mic.
We would welcome a review of the schematic and PCB design. Suggestions are welcome, but contributions much more so! Many hardware and software tasks are available for volunteers who are interested in contributing to the free and open future of Digital Voice. Rick Barnich KA8BMA is a recently retired engineer who is a veteran of over 100 PCB designs. He has done a fantastic job at schematic entry, sourcing parts, analog and digital design, and PCB layout – and he is having a great time in the process!
Rick and I are currently wrapping up the schematic and PCB design, and will be building up prototypes and various pieces of software over the next few months. Most of the analog design has been prototyped, Codec 2 is running on the micro-controller, but the modem still needs some work to reduce memory use. Lots of work required for the user interface, integration, and general micro-controller software.