Motorola repeater programming question

[piper451]

I'm hoping someone can help me out with an issue I'm having with a recently "built" repeater. A little background - the repeater is comprised of a vhf motorola turbo 4500 and a vhf motorola cdm 750 with a repeater controller. Everything works great, with 1 exception. The mdc1200 signaling does not pass through the repeater. In other words the mdc1200 radio Id from the transmit portable is not being displayed on the receive portable. Am I missing a piece of hardware in the system or is this a programming issue? Any help would be appreciated. And yes - this is a licensed repeater. Thank you


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[mikewazowski]

Whatever radio you're using for receive is probably muting the MDC tones. Can you hear the MDC tones going out over the repeater?

 

[piper451]

No I'm not hearing the tones coming out of the repeater. Is there a specific setting in the software that mutes the mdc?


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[RKG]

Just a guess, but go to Signalling|MDC System|DOS|DOS Auto Mute Duration, and set it for "Disabled."

 

[12dbsinad]

Need a little more info here. Are you using pre or post in regards to sending the MDC? DPL or PL? DPL usually has a slower decode than PL and can cause problems with sending MDC upon transmit. Are you near the repeater? If so, listen to the RX radios speaker, do you hear the complete MDC or is the RX radio set to mute it, which could explain why it doesnt work. I'm leaning towards muting as being the problem.

 

[piper451]

I'm using a pre dpl. I'm not hearing anything that sounds like an mdc code coming out of the rx radio upon keying up the repeater. Not sure if it matters but I have the rx radio set up as a receive only profile. Thanks a bunch for the replies.


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[sfd119]

You built a repeater? Using Motorola radios?? If you have MDC Decode enabled on the RX side of the repeater, it won't TX the MDC idea across because the first radio is already decoding it.

 

[SteveC0625]

You built a repeater? Using Motorola radios?? If you have MDC Decode enabled on the RX side of the repeater, it won't TX the MDC idea across because the first radio is already decoding it.

+1 on this *if* the Rx side of the repeater is the 4500. The CDM750 won't decode MDC so if it is the Rx radio, then there is another problem somewhere. The 750 should just pass the MDC as audio if it is Post.

If the OP is using Pre for MDC, it is likely not getting passed because of lag time to key up the Tx side of the repeater.

Perhaps a better description of the repeater and the programming of both of those radios and the mobile/portable units might be in order. Otherwise, while all of us have offered good thoughts, without knowing more about the system, we can't know which of our solutions are even applicable.

 

[902]

My first step would be identifying exactly where in the chain there is MDC audio and where there is not.

1) Go to the receiving radio and listen to the output into the controller (or use an oscilloscope to see the waveform). DO NOT listen to the speaker output, as what you hear on the speaker may not necessarily be what's going out of the radio's accessory connector. You should see the MDC waveform there. If not, you don't need to go any further, the receiving radio is, for some reason, eliminating it.

2) Go to the output of the controller. Same procedure as above. You should see the MDC waveform there. If you don't, the controller is eliminating it for some reason.

3) If for some chance you see MDC audio at both of the points above, and you're not getting it out of the transmitting radio, then THAT is what's eliminating it.

Troubleshooting is always a methodical process that looks for what is where it should be, and if it's not there, then dives in further to isolate the point where the unfavorable condition manifests.

All that said, Mike is probably right. Your receiving radio is probably programmed to mute the MDC signal and you are extracting audio not at the discriminator, but after the squelch gating and processing. If you don't get the MDC signal out of your receiving radio, start looking at how you configured it in programming software.

 

[piper451]

This is all excellent info, thank you very much. Just for the record, the cdm750 is the rx radio. I think the first thing I will do is move the mdc to a post transmit position on the portable radio and see what happens. I checked the software last night and I didn't see any settings under signaling that are set to mute mdc.


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