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MLC8000 simplex voting problem

Posted: Tue Nov 11, 2014 2:43 pm
by IMBEJames
I'm having an issue with a new voting system we just installed... It is an IP simulcast system with 3 transmit sites and a handful of Rx-only sites, and is simplex analog. Transmit sites all consist of GTR8000 stations with MLC8000's, and receive sites are a mix of Quantars, ATAC receivers and MTR3000's set up as Rx-only.

The problem is, there is one site that is receiving console audio and being voted, causing an echo at the op positions. The comparator display in the MLC Configuration Tool shows the site being voted, but does not show a receive indication from any other Rx-only site. I tried swapping the MLC with a spare and still get the same issue. The configuration of the problematic AGU is identical to all other Rx-only units. The receiver is the only MTR3000 in the mix, but it is set up as Rx-only with status tone, just like all the other receivers. Also, I can't imagine there is an issue with the VGU, as all other sites function perfectly. Console is Gold Elite, but shouldn't make any difference.

Has anyone else come across this? It's driving me nuts...

Re: MLC8000 simplex voting problem

Posted: Tue Nov 11, 2014 6:18 pm
by d119
Sounds like that site isn't aware this is a simplex system and should be quiet when the console is transmitting.

You could also configure the console as a 2W interface instead of 4W and get rid of the duplexed audio.

Got a logging recorder on this? I'd love to hear what the voted audio from an MLC8000 sounds like... PM me for an email address.

Re: MLC8000 simplex voting problem

Posted: Wed Nov 12, 2014 3:09 pm
by IMBEJames
No logging recorder that I can access, but if I can somehow get something for you I'll let you know. The only way I can describe the audio (both Tx and Rx) is AMAZING. The MLC8000's use G.711ulaw for a codec. IMO, the audio is superior to what you'd get out of a JPS.

Since each site in an analog simulcast system has an MLC8000 as a subsite link converter, the MLC's handle the voting and control of the sites with the receivers connected via 2W circuit. Thing is, I can't find any way to tell the system not to vote when the console is transmitting. The configuration is pretty basic, and there isn't much that can be changed.

Also, the console interface to the MLC8000 configured as the VGU has to be 4W. I can't find any other options in the config.

I suppose I could set up 4W muting at the BIM during PTT, but it's been a while since I've been that deep into Centracom stuff... Any ideas?

Re: MLC8000 simplex voting problem

Posted: Fri Feb 09, 2018 12:59 pm
by quint 18
Good afternoon did you ever find any resolution to this? I have a new installed MCC7500 we are having the exact same issue,on the Gold elite we could change the wireline from 4 wire full duplex to 4 wire half duplex and solve the "echo". But as motorola would have it there is no way to configure a CCGW (on 7.11) for this function as I understand it. The only close to reasonable solution that has been developed is to interrupt the RX pair of the wireline during TX this requires the addition of relays and power supplies and the like. Not really the way it should be handled on a radio system in 2018. So hopefully you have solved this issue and are willing to share!

Thanks so much for your time

Frederick Kinder

Frederick Co Va