MMDVM Digital Voice Hotspot
What it is
A personal digital voice hotspot: a Raspberry Pi 5 with a duplex MMDVM hat, running WPSD. It puts a low-power digital voice access point on my desk, so a handheld can reach the digital voice networks without needing to be in range of a repeater.
Being duplex, it transmits and receives simultaneously on separate frequencies, so it behaves like a miniature repeater rather than imposing the turn-taking a simplex hotspot requires. It gives me access to both the DMR and YSF (System Fusion) networks, and works with the FT5D handheld and the FTM-200DE in the shack.
It appears in my radios’ memory files as the G0LFT HOTSPOT channel: 438.725 MHz receive, 434.725 MHz transmit, in Fusion (DN) mode with the wide IF filter, which C4FM needs to decode reliably.
Why I built it
Cambridge has repeater coverage, but a hotspot removes the dependency entirely. It works from indoors, at very low power, and lets me move between the digital voice networks without retuning anything. It’s also the most convenient way to experiment with the digital modes, since reflectors and talkgroups become a configuration change rather than a drive to somewhere with coverage.
It’s the piece of infrastructure that made the digital side of the hobby practical for me day to day, which is why the wide-IF discovery it prompted ended up baked into my memory-channel builder.
Current status & goals
- Built and in daily use, running WPSD on a Pi 5 with a duplex MMDVM hat.
- Gives access to the DMR and YSF networks.
- Works with the FT5D handheld and the FTM-200DE via the same
G0LFT HOTSPOTmemory channel.
