P25 Simulcast Reception Woes - BCD-996T - BCD-996XT - BCD-996P2

[kb0nhx]

For years everyone that's had one of the BCD996T, BCD996XT or BCD996P2 scanners has generally had problems with distorted, garbled audio on P25 Simulcast systems using CQPSK / Linear Simulcast Modulation.

I've seen many threads, including one that mentioned the problem cannot be solved by firmware because it's a hardware problem with these scanners and Uniden's only answer was to design and release the SDS line of scanners.

I'm wondering if anyone has considered a diversity antenna system for 996 series scanners? Technically, I don't know what would be involved to integrate the idea - is it a radio hardware / multiple receiver in one scanner deal or is it simply building a diversity antenna system and feeding it into the Uniden scanner antenna port. I do know that the purpose of diversity receive antennas is to combat multi-path and it seems like that might be a solution for those of us with the older scanners.

Second question: How do the BCD536/436HP Scanners / Home Patrol scanners perform with LSM systems? I've not tried either. I DO know none of the above work well and the SDS-200 I've got to observe seemed to handle LSM flawlessly.

 

[bobruzzo]

For years everyone that's had one of the BCD996T, BCD996XT or BCD996P2 scanners has generally had problems with distorted, garbled audio on P25 Simulcast systems using CQPSK / Linear Simulcast Modulation.

I've seen many threads, including one that mentioned the problem cannot be solved by firmware because it's a hardware problem with these scanners and Uniden's only answer was to design and release the SDS line of scanners.

I'm wondering if anyone has considered a diversity antenna system for 996 series scanners? Technically, I don't know what would be involved to integrate the idea - is it a radio hardware / multiple receiver in one scanner deal or is it simply building a diversity antenna system and feeding it into the Uniden scanner antenna port. I do know that the purpose of diversity receive antennas is to combat multi-path and it seems like that might be a solution for those of us with the older scanners.

Second question: How do the BCD536/436HP Scanners / Home Patrol scanners perform with LSM systems? I've not tried either. I DO know none of the above work well and the SDS-200 I've got to observe seemed to handle LSM flawlessly.

The only thing that worked for me after MONTHS of trying, was an 800mhz yagi. Still get a little distortion but less with yagi. My SDS200 still gets simulcast distortion but very little using yagi and filters. Tried all different directions pointing yagi and works best pointing AWAY from areas where the state systems towers/antennas are. I have a BCD996P2 in my car and using a short tri-band (vhf/uhf/800) antenna, works pretty well.

 

[trentbob]

Simulcast Distortion secondary to LSM is tricky business.

When you have multiple towers that are close together simultaneously broadcasting the same thing your radio is calling for you get the simulcast distortion in simplistic terms so the idea with an antenna is to compromise reception in an attempt to isolate reception to 1 Tower over another.

Some of the methods used are a paperclip, take a used paint can, drill a hole in it and stick the rubber duck of a portable in the hole. The comet CH 32 miracle baby could work.

It's basically your location in relation to the simulcast towers and how close they are to each other and you. People have tried using a yagi directional antenna but that can be problematic too because it works in both directions LOL. You will often hear people in the next County who can only receive one Tower who say they don't understand what the problem is it comes in great for me LOL.

These are all unpredictable gimmicks and might work depending on your location location location but if you want to overcome simulcast distortion secretary to LSM, use an SDR scanner, use SDR, get a unication pager or a non-affiliated RX only professional commercial radio. There are a few other options out there that aren't mainstream yet but will work.

So that others here can help you specifically with the system's you're trying to receive you should let everyone know exactly what those systems are, depending on the type of system it is there might be other options depending if you can opt out of different sites. Hope this helps... Bob

 

[hiegtx]

Take a look at this thread in the Whistler forum, from someone else in your county:

P25 ScanList

I am hoping someone can assist me with a troubleshooting issue on a TRX-2have a scanlist loaded with a P25 system, ie, Sheriff, fire, etc, that I am not hearing. I have double checked and triple checked the “trucked Radio System” tab, site list, talkgroup details, all appears as it should. I...

forums.radioreference.com

Look at this page in the Wiki regarding Simulcast:
Simulcast digital distortion - The RadioReference Wiki

Are you, like the other member, struggling to hear Springfield, MO?
This is the Greene County Simulcast site:



A directional antenna, such as a yagi, aimed at a specific transmit tower, might allow you to hear that site without problems, However, the directional antenna could hinder your reception from other locations in different directions. Alternatively, if your signal from the site is strong enough, less antenna, including the proverbial paper clip, might work to hear the simulcast site without problems.

The x36HP scanners (436HP and 536HP) are marginally a little better with simulcast than the P2 series (325P2 & 996P2), but not by a large margin. The HP-2 would likely be somewhat worse than the P2 scanners. (I don't have simulcast systems programmed in my HP-2.)

 

[trentbob]

Wow that's a good testimonial, three people basically posting the same ideas simultaneously.