New radio! This one is an MMDVM hotspot assembled for and sold by Radioddity. The part I got is clearly labelled "Made in China", but it was shipped promptly from the Radioddity depot in Las Vegas, Nevada. It arrived in a small cardboard box with a single page of tutorial instructions and a few extra screws.
The tutorial text is "Geek Teches THE MMDVM DMR TUTORIAL". I'm certain that it reads better in whatever language it was originally written in, and frankly the text is confusing at best. Fortunately the software and hardware is an ordinary MMDVM and Pi-Star configuration, and there's plenty of good tutorials for that.
Some useful tutorials include:
- Playing with Pi-Star, Amateur Radio Notes, Toshen KE0FHS
- Pi-Star Digital Voice Software, Pi-Star. Official docs
- Pi-Star integration with Brandmeister API, Brandmeister wiki
Nick W8XM was very helpful - I happened to catch him on the ARROW 2m FM repeater while I was putting things together, and I related the problem I had originally where people could hear me but I could not hear their return. It seems that the hardware in this kit is subject to frequency drift, and you need to tune the "RX Offset" with some trial and error (using Parrot) to get an accceptably low BER. At zero offset I had 1.3% error rate; after tuning to -200 my BER was down to 0.2%. Ailunce has a good description of what you need to get to.
I had one glitch on setup - typing in the wrong wifi SSID for our home network! - and had to manually add a new wpa_supplicant.conf file to the SD card to make it work. Fortunately, this tutorial from KE0FHS made that quick work.
The Brandmeister network does not like hear lots of short transmissions in sequence from a single station, so if you are testing things out vigorously and punching a lot of buttons in short sequence you might get a user blocked voice message from the network. This corrected itself for me by waiting an hour.
With all of that set up, I'm back on the air with DMR. There's a weekly Michigan net via Michigan One DMR, and the Brandmeister Feditalk talkgroup is one I hope to make more contacts on.
73 de Ed W8EMV
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