missing audio

[flyboy4545]

I am using two to three radios at the same time to receive cmpd traffic. I have three xts5000s , sds100 and a bcd536. Between the five i can listen to all the traffic. All radios have been programmed with the control frequencies listed on radio reference website. Its just odd to me. Is this a signal issue due to being p25 digital? The bcd536 picks up very little even with an 800 antenna. The sds100 and the xts5000s pick up most of the time but seems to randomly stop at different times. Sometimes if I cut off and back on the xts5000s , it seems to work. Are there any frequencies missing from the rr page? Any ideas?

 

[RaleighGuy]

Isn't CMPD a simulcast system? The BCD536 doesn't play nice with simulcast while the SDS100 was designed to.

 

[hamstang]

Isn't CMPD a simulcast system? The BCD536 doesn't play nice with simulcast while the SDS100 was designed to.

Exactly

 

[rescue161]

Probably have an error in the band tables (Astro 25 Channel ID).

 

[flyboy4545]

cmpd does not have a simulcast anymore. It was the analog system which is gone now. Rescue161, I sitll think its a signal problem. Maybe a tuning or rf board issue.

 

[drayd48]

cmpd does not have a simulcast anymore. It was the analog system which is gone now. Rescue161, I sitll think its a signal problem. Maybe a tuning or rf board issue.

CMPD uses the Charlotte UASI system, in which the Mecklenburg site is a simulcast system consisting of around 10 towers or so if I remember correctly. As stated above, the older Uniden scanners don't play well with a simulcast system. Your XTS and SDS were designed to pick up a simulcast system. I would assume that you are using non-affiliate with the XTS and sometimes the older XTS radios get held up while scanning and just stop. Those radios have been discontinued for almost 10 years now so that makes sense. A little trick to get your BCD working is to try using a paperclip in your antenna slot, but be careful, so that you are only picking up one tower or using a YAGI and point it directly at the closest tower.

 

[rescue161]

The XTS5000 is not susceptible to simulcast problems (if it is aligned and programmed properly), so if you are missing traffic, then more than likely your Astro25 Channel ID table is wrong. If turning it off and then on again fixes it temporarily, then I'd revisit that area in CPS. Details for for what goes in these fields is not listed on the database for CMPD, so you'll have to use UniTrunker to pull that data from the control channel. You can have the correct control channels programmed right, but if you don't have your band tables set correctly, you will miss traffic.

 

[RF-Burns]

Correct Channel ID for UASI.

 

[flyboy4545]

All of that is correct but one thing. I changed 769.00625 to 762.00625. Can you explain how you got that and how that is, as the radio is list 764mhz and up.

 

[rescue161]

The Astro 25 Channel ID tables only set the base frequency and step, so it can create a map for the radio to tune to certain frequencies when a control channel gives it a channel. If you have 769.00625 as a start freq and the step is set to 6.25 kHz, then it could miss portions of a conversation. The following isn't 100% correct, but it is close. Let's say your XTS5000 gets an inbound signal from the control channel that tells your radio to go to 770.84375. It will give a line number instead of the frequency, so your radio will get a message that tells it to go to line number 1414. If your radio was set the way you had it programmed, your radio would (try to) tune to 777.84375 and you would miss the traffic that was happening on 770.84375. For some portion of the time, the line numbers would line up, hence why you heard some traffic and missed other messages.

 

[flyboy4545]

I understand. Where can I find the 100% correct base frequencies?

 

[rescue161]

RF-Burns posted the info in post number 8.

You can also use a program called UniTrunker with a scanner to decode the control channel data and it will spit out the correct info too.

 

[flyboy4545]

including base frequencies?

 

[rescue161]

There are two frequencies that you enter into the Astro25 Channel ID for that system.

851.00625 & 762.00625 are the base freqs. You then set the spacing for 6.25kHz on each of those. You set the offset for 851.00625 for -45MHz and 30MHz for 762.00625. Both are set for FDMA.

These are not entered in the control channels area of CPS. This info is set in the "Astro25 Channel ID" area.

 

[flyboy4545]

I re-read the second to last post and understand thanks for your help.

 

[rescue161]

 

[flyboy4545]

Right. All that has been set. But my cps does not have an area in astro 25 channel id to select FDMA. Is that okay?

 

[rescue161]

That is fine, because the XTS5000 won't do TDMA, so the default is FDMA.

 

[flyboy4545]

Thank you.

 

[rescue161]

Is it working better now? Make sure to set your other radios/scanners the same way, so they'll track the system correctly.