BCD396T - No RX on control channel, but only in trunking mode

[aaknitt]

Trying to figure out a strange problem I'm having with my BCD396T. Local trunked system has 851.750 MHz as one of the control channels. If I manually enter that frequency by hitting "HOLD" => 851.75 => "HOLD" I can hear the control channel load and clear. I have that same frequency programmed as one of the control channels in my trunked system, but when scanning the trunked system it doesn't get anything on that channel.

If, while scanning the trunked system, I hit "HOLD", the radio shows 851.7500 MHz, but no signal strength is shown and no audio is present, as if there is no signal on that frequency. however, if I listen on another scanner or manually go to that frequency (outside of the trunked system), the control channel is there loud and clear.

If I program 851.7525 MHz into the trunked system instead of 851.750 MHz, it will then receive the control channel data, even though the frequency is off. I'm confused, what gives? Any ideas?

Thanks,

Andy

 

[ko6jw_2]

OK, you don't say whether you can monitor the trunked system normally. If you can, then why do you want to hear the control channel? You're not supposed to hear it when you monitor a trunked system. It's digital information that is used for a variety of purposes like telling your radio which channel to listen to. It contains no information that you can hear (unless your brain processes digital signals).

Or, your question is way to subtle for me and you are part of the monitoring hobby that only listens to control channels.

 

[aaknitt]

OK, you don't say whether you can monitor the trunked system normally.

I can monitor the trunked system "normally" by programming 851.7525 as a control channel, even though the actual control channel frequency is 851.750. When I program 851.750 as a control channel, it does not decode the channel or receive anything on the channel, even though when I manually tune to that frequency (outside of the trunking system), I can receive that channel with no problem.

I fully understand how trunked radio systems function. I'm trying to understand why my scanner isn't behaving as expected.

Andy

 

[ko6jw_2]

Very peculiar. Is there more than one site and thus more than one control channel? What is the name of the system?

 

[KevinC]

What system is this?

 

[aaknitt]

Very peculiar. Is there more than one site and thus more than one control channel? What is the name of the system?

No, it's a simulcast system, so only one control channel. The system is the Waukesha County, WI 800 MHz public safety system.

Andy

 

[KevinC]

Do you have the custom tables for rebanding applied?

 

[aaknitt]

Do you have the custom tables for rebanding applied?

Yes, and it will track the system just fine when I put in 851.7525 as the control channel freq, but it will not when I put 851.750 in as the control channel freq. 851.750 is the actual licensed frequency.

Andy

 

[jonwienke]

I would try listening to the channel with another radio. A 2.5KHz deviation from nominal could be a misprogramming of the transmitter. In many cases, that small of a mistune won't be noticeable.

 

[aaknitt]

I would try listening to the channel with another radio. A 2.5KHz deviation from nominal could be a misprogramming of the transmitter. In many cases, that small of a mistune won't be noticeable.

Yep, I've done that. It comes in loud and clear on 851.750, both on another radio and on that same radio when monitoring it as a conventional channel. However, when programmed in as a control channel in the trunked system, I get no reception on that frequency (no signal strength or audio).

Andy

 

[jonwienke]

Then my guess would be that the scanner is ignoring what it (erroneously) thinks is an invalid frequency value. Have you tried looking at the scanner's default band settings to see whether 851.7500 or 851.7525 conforms to the band plan?

 

[ko6jw_2]

These types of questions are not easy to deal with from outside the area. You usually just tell the person something they already knew. I curious, the DB says that the system is in the process of being rebanded and it shows three control channels (probably alternates). Is it possible that the change you are noting is part of that process and it's the RR DB that's off? It's not a complex system and if you can track it by tweaking the control channel what is the answer? The correct control channel frequency is the one that allows you to receive the system. Yet, a 2.5Khz deviation should not cause the problem you describe - the 396T is not that selective (I have one). Very puzzling.