BC796D P25 choppy reception with strong signal?

[bnchester]

I just got a used BC796D to monitor my local APCO 25 system. I've got it all programmed, and I have a very strong signal -- the transmitter is visible my roof antenna, and my BC396D monitors the system very clearly. I am pretty sure I have the system programmed correctly - programmed it from RR via ARC250.

Here's the issue. When it lands on an active TG, the transmissions, while clear, cut out every half second. While I hear the transmissions, the indicator flips rapidly between "P25" and "FM". During ID SEARCH it flips rapidly between DAT and FM while displaying the control channel frequency of 859.8875. My 396 shows a solid P25 during reception of a transmission and DAT while searching.

Conventional transmissions are absolutely fine.

It is all but unusable the way it is. Do these symptoms sound familiar to anyone, and/or does anyone have any ideas how to resolve? I have messed around with the P25 "sound quality" adjustments, but to no avail.

Thanks!
Barry

 

[W6KRU]

It sounds like you have a weather or priority function set.

 

[bnchester]

It does sound kind of like that but (a) I don't (I did a factory reset before programming it) and (b) those functions don't interrupt the tx so frequently.

I could probably take a video of it and post it of people think that would help.

 

[MarMatthias]

It does sound kind of like that but (a) I don't (I did a factory reset before programming it) and (b) those functions don't interrupt the tx so frequently.

I could probably take a video of it and post it of people think that would help.

Do you have anything that could be interfering with it in close range? Have you tried your AGC settings? Does the P25 LP filter have any effect?

 

[Dewey]

I'm with DDan. I haven't operated the 250/785 & 296/796 family in a L-O-N-G time, but if I remember correctly, the priorty channels are programmed by bank. I'm reaching here, but have you tried going to a conventional channel in the bank affected (even if it's 000.0000), and turning off the priority. The fact that you mention alternating between FM and digital modes may be an indication that it is sampling a conventional priority frequency.

Dewey

BTW... I didn't think the 796 had a P25 LP filter.

 

[bnchester]

796 doesn't have AGC settings or LP filter. Priority is definitely not on.

I have reduced the programming down to the bare minimum:
1. I did a factory reset.
2. I entered only the control channel frequency, set up the trunking system to type 1 (which it is), and put it in control channel only mode.

While ID searching, when there are no active TGs the display rapidly alternates between NFM and DAT, literally every half second, not every two seconds like priority scan would. When there is an active TG, it alternates between NFM and P25 at the same rate, and when it shows NFM it cuts out the broadcast.

I thought maybe it was something like I had one of the trunking frequencies programmed as conventional, which is why I reset the scanner and redid the programming so minimally.

Any other thoughts? Would a video help?

 

[Highpockets]

Can you post a link to the system your listening to. There was an upgrade put out for that scanner, was it done?

 

[Highpockets]

You mentioned Type I system, did you set the right fleet map, I would think one would be needed.

 

[bnchester]

This is the system I am monitoring: Tompkins County Public Safety Trunking System, Ithaca, New York - Scanner Frequencies. How would I know if I have the latest firmware and how would I update it?

I didn't mean type I, I meant plan 1. My error.

Thanks.

 

[bnchester]

The firmware version on the scanner is 3.21

 

[lebrunmn]

Please check your Control Chan Only Plan...

Bnchester-

Think you may be using the wrong control channel only plan... Based on the info you provided about the system, I think you should be on Plan 3 or Plan 4, not plan 1. See below:

3LAN3
Use if the last three digits of all the frequencies in the system end in 000, 250, 500,
or 750.

4LAN4
Use if the highest frequency in the system is below 866 MHz and if the last three
digits end in 000, 125, 250, 375, 500, 625, 750, or 875.

I hope this helps your problem.

Regards,

 

[bnchester]

I upgraded the firmware, not at 3.60. Mark, thanks for the tip. I changed the plan to 4 -- no change. This is frustrating!

 

[Highpockets]

For the heck of it, add all the frequencies and don't use CC Only mode and try it.

 

[Highpockets]

Also, what type of system are you setting it up as, can you pick a choice for 9600 baud P25 system?

 

[lebrunmn]

You might try plan 3, as well... I was re-reading the post, and think that plan may be an option, too. It certainly can't hurt.

Clearly your scanner's not trunktracking properly, but you already knew that. I second HIghpocket's suggestion of entering all the frequencies, and seeing what that does.

Also, are you using programming software? If yes, to rule out some wierd setting on the software, we could try sending you a fresh file for the system. I can do that if you like.

Regards,

 

[stephend]

Barry (bnchester),
Wondering if you found out the problem with your BC796D scanner P25 trunking? I think I had the same problem.
Stephen

 

[bnchester]

Mark,

I am using ARC250. I don't recall seeing the suggestion to program all the frequencies, but I know I did that at one point. When I can make a few minutes I may do that again, and also try the different plan settings. What do you mean by sending a "fresh file" for the system?

Stephen,

Do you mean you had it and solved it, or that you have it and want the solution if I find it? If the former, please share! If the latter, of course I will post it. As you can see, I have a couple of things to try next.

Barry

 

[lebrunmn]

Barry-

By a "fresh file" I meant a freshly downloaded Tomkins County ARC250 file. Just trying to rule out any wierd software settings that may be causing your problem--although none immediately come to mind. I quickly set one up a test file for Tomkins County, and have attached to this post, changing the .mem to .txt file for uploading. You could try loading this file to see if this eliminates your problem.

One more thought--and you've probably already tried it--have you tried removing and reinserting the PCi card?

Regards,

 

[stephend]

BCi96DVUP_1_03

Barry (bnchester),
At one time I know I updated my BCi card. For some reason it must have gotten corrupted. I had the problem where when they started talking, it would be interuped, almost like a priority channel was being checked, but faster. Then it would try to talk again only to be interupted again. It was frustrating. Finally I decided to do the update of the card again. This fixed the problem. I installed the 1.03 BCi card update. Hope this helps.
Stephen

 

[bnchester]

Mark, uploaded your file to a freshly cleared system -- same result. And yes, I did remove and reseat the card.

Stephen, are you talking about updating the card hardware, or firmware? Whichever the answer, how do you get it? Your symptoms sound similar to mine and you seem to have fixed your problem.