MMDVM hotspot -- DR-2X repeater bridge

Help with YSF / Fusion issues
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KD5GR
Posts: 2
Joined: Wed Sep 23, 2020 4:38 pm

MMDVM hotspot -- DR-2X repeater bridge

Post by KD5GR »

I've searched this topic and can't find anything. If it has been discussed and I missed it, then I apologize.

We have two DR-2X repeaters running AMS/AMS. We want to bridge the 2-meter repeater to our FCS 00388 node using an MMDVM hotspot. The hotspot is running separate TX/RX frequencies using the appropriate repeater uplink/downlink frequencies. Testing with HTs has been perfect. However, there is a problem.

When the hotspot is next to the repeater, the repeater receives the hotspot's transmission, but it "thinks" it's FM, not C4FM. When set in AMS/AMS, the repeater won't transmit what it receives. When it set in AMS/Fixed Digital, it will transmit what it received, but it's just digital hash.

We have looked at the hotspot output with a station monitor and compared it to the output from two different Yaesu HT's (FT5 & FT70). It is markedly different. Both HT's transmit a very short sine wave, then the digital wave can be seen superimposed on the sine wave. However, the hotspot transmits a much longer sine wave before the digital wave is seen. It's clear that the longer sine wave is what is making the DR-2X repeater think it is receiving analog FM instead of C4FM. We have tried making numerous changes to the pi-star configuration, but nothing has fixed the problem.

The problem is clearly with the MMDVM/Pi-star combination, because an OpenSpot2 works perfectly in this application. The repeater receives the OpenSpot2 signal and transmits it in C4FM.

Has anyone dealt with this problem? Three guys with a lot of test equipment are out of ideas. We know the cause of the problem, but not a fix.

Thanks,
Chas.
M1DNS
Pi-Star Team
Posts: 1388
Joined: Thu Apr 05, 2018 5:30 am

Re: MMDVM hotspot -- DR-2X repeater bridge

Post by M1DNS »

This isn't a usecase pistar was intended, to be used as a rf bridge. so most prob. why no one else has taken to asking.

Sent via smoke signals from my SM-G935F M1DNS (Admin)

Andrew M1DNS.
Pi-star Admin Team.
KD5GR
Posts: 2
Joined: Wed Sep 23, 2020 4:38 pm

Re: MMDVM hotspot -- DR-2X repeater bridge

Post by KD5GR »

The problem has been solved. All settings were correct, except for one -- of course!

Here are some of the settings:
Controller Software: MMDVMHost
Controller Mode: Duplex repeater (or half duplex on hotspots)
Radio/modem type = MMDVM_HS_Dual_Band for Pi (GPIO) (We are not using a duplex board. This setting is required to be able to use different RX/TX frequencies
VHF frequencies set for our repeater uplink/downlink; and activating only YSF Mode.

The problem setting was in Expert/MMDVMHost/System Fusion. The RemoteGateway was set "0" and needed to be "1."

The hotspot now works well as an rf bridge allowing people to get to our Club VHF repeater through our FCS Reflector. There are four repeaters of which I am aware using this set-up. One of their technical officers gave me the RemoteGateway setting.

I hope this helps someone wanting to set up the same system.


Chas.
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