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Author Topic: Linking P25 Repeaters  (Read 161 times)

KB8VUL

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Linking P25 Repeaters
« on: March 23, 2023, 07:36:53 PM »

Anyone running a linked P25 repeater setup?
I currently have a Quantar connected to the P25.link system and I was wondering how many others were out there running MMDVM or other connections on P25. 
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K4JJL

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Re: Linking P25 Repeaters
« Reply #1 on: March 24, 2023, 05:30:47 AM »

My friend linked 2 repeaters via RF.  He used 4 Quantars.  Each site has 2 connected via the V.24 interface.

If you're going with an internet link, you'll need a couple of Cisco routers w/ a V.24 interface.

Here's a link to how one guy did it...

https://www.qsl.net/kb9mwr/projects/dv/apco25/IP%20link%20Quantar%20V.24%20systems%20using%20Cisco%20routers%20V2.pdf
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KB8VUL

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Re: Linking P25 Repeaters
« Reply #2 on: March 24, 2023, 06:05:43 AM »

Yep, that's basically what i am doing but there is a Raspberry Pi involved that routes traffic to different MMDVM and P25 reflectors based on the talkgroup data it see's in the data stream.  There are also TG reflectors on the system that are system specific and don't have an MMDVM reflector associated with them.
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K4JJL

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Re: Linking P25 Repeaters
« Reply #3 on: March 24, 2023, 01:36:48 PM »

I wouldn't rely on it long term.  The MMDVM stuff is flaky at best.  Mine randomly disconnects.  Another one of my friends set up a P25 reflector and crossed it to a DMR reflector on Brandmeister.  It works ok, but, like I said, it randomly disconnects.

We haven't actually tried using it to link repeaters.  Just as hotspots.
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KB8VUL

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Re: Linking P25 Repeaters
« Reply #4 on: March 24, 2023, 08:11:50 PM »

I wouldn't rely on it long term.  The MMDVM stuff is flaky at best.  Mine randomly disconnects.  Another one of my friends set up a P25 reflector and crossed it to a DMR reflector on Brandmeister.  It works ok, but, like I said, it randomly disconnects.

We haven't actually tried using it to link repeaters.  Just as hotspots.

Well, it is transported across the Internet.  And it's ham radio level stuff and not public safety grade connections.  But that discussion goes back to the idea that has been beat into the ground about ham operators, especially the EMCOMM guys having too much reliance on the Internet for communications.  It's just a bad idea.
The site in question this is all setup at (tower site) has three different paths to the Internet.  There is a local DSL service, a T-Mobile 5G modem, a microwave link to the owners house and a microwave link to my house that serve Internet to the site.  The routing gets a bit funky though due to the VPN tunnels that are used to link the repeater to the core down in FL have to reconnect when a connection drops. 
We are looking at getting a fourth connection spun up this year that will be a microwave link into a building in the nearest major city that will be fiber fed from that building.  That is part of a much larger AREDN network project we are working on.  But that's a story for a different time.

Biggest thing I am trying to find out is who else is linking via the system I am on. 
I understand the idea of site to site linking of P25 repeaters via Cisco routers and STUN tunnels, but those are strictly a point to point or point to multipoint setup that doesn't directly connect to the Internet and doesn't route P25 traffic to P25 reflectors like this one does. 
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