Since the last post in this series Rick, KA8BMA, has been working steadily on the CAD work for the SM2000 VHF Radio. We now have the SM2000 schematic and 80% of the PCB layout is complete. Rick has taken a modular approach, laying out each building block that I prototyped last year.
Here is the current state of the PCB layout, which is 160mm x 160mm
On the waveform side, Brady, KC9TPA, has done a fine job porting a 4FSK modem to C and developing two new VHF FreeDV modes. ModeA is an “optimal” 4FSK mode that runs at 2400 bit/s, has a 5kHz RF bandwidth and a MDS of -132dBm. ModeB use Manchester-encoded 2FSK at 2400 bit/s and will run over any FM radio, even $40 HTs.
Brady’s modem is also being used for our high speed balloon telemetry work.
There is plenty of software work (e.g. STM32F4 micro-controller code) to be done for the SM2000. Help wanted!
SM2000 Part 1 – Introducing the project
SM2000 SVN – CAD Files for the project