BCD996T P25 Tweaks?

[jthorpe]

Ok, so ever since I changed software on my 996 from the version it came with, P25 audio on VIPER has been horrible. I believe that it's just seeing the issue on the Wake County Simulcast system but I don't know for sure because I never listen to P25 outside of Wake County. So anyways, those of you who have gotten yours to work well, I'm wondering what settings you're using. I will post mine as a comparison. Any advice would be appreciated...

Firmware Version: 3.02.00
P25 waiting time - 400ms
P25 Adjust Level - 30
P25 Adjust mode - 4
Analog and Digital AGC are on
P25 Decode Threshold Level - Manual 11 (seems to be getting less errors that way)

If there is anything else you're curious about in terms of my programming, feel free to ask. The only thing that I can say is that ever since I changed the original firmware on this thing, P25 audio is choppy. Sometimes it's not but most of the time it is. I have a 6 element yagi pointed at the training academy from 5 miles away and still get this problem. It's been frustrating to say the least. My xts 5000 in the house with rubber duck antenna does better than the scanner with the yagi. Thanks again....

 

[jthorpe]

Dang. Crickets. No advice?

 

[KE4ZNR]

Dang. Crickets. No advice?

Hey brother I am running a 996xt but maybe we can find some time to put the 2 radios side by side and figure out what is amiss. The XT obviously has different firmware and filtering but we can work together and get the problem solved I bet.
Drop me an email and we will set something up.
Marshall KE4ZNR

 

[jthorpe]

Thanks Marshall, I would appreciate it. Can you tell me what your settings are so I can see at least if tht helps? I've been trying to get this thing to work for a year now, and I'm getting close to putting a .357 round through it.

 

[jthorpe]

Well, DOWNGRADED the firmware back to 1.04.12 and now my P25 audio is just as good as my XTS-5000 sitting beside it. Go figure. It's great until rebanding time, which won't be too far down the road. At that time, I'll either run this thing over or sell it.

 

[KE4ZNR]

Well, DOWNGRADED the firmware back to 1.04.12 and now my P25 audio is just as good as my XTS-5000 sitting beside it. Go figure. It's great until rebanding time, which won't be too far down the road. At that time, I'll either run this thing over or sell it.

I still want to catch up with you sometime soon and see if we can't figure this out. I am glad that you are back up and running in some capacity but obviously the best scenario is to have you on the latest firmware.
Let me know via email/phone when you can catch up with me.
Marshall KE4ZNR

 

[jthorpe]

I have the next few days off. I am going to try and get up with you this week. But yeah, since I put the old version back on, the scanner has sounded awesome.

 

[jthorpe]

Old thread, but I am still having issues with this. I can put this 996T next to a 796D and there is no comparison. The 796 beats the 996 receiving digital P25 all day long. Now that is sad. This 996 was supposed to be the best thing ever but I have had nothing but problems on the wake Simulcast. Nothing but. I'm glad most of the SHP stuff is still mostly analog.

 

[jackj]

I monitor Ohio MARCS using a 996T and the radio was CRAP when I first received it. I couldn't even understand the dispatcher most of the time. Uniden has come out with two firmware upgrades since and the last one seems to have fixed all of my problems. Check Uniden's web site and make sure you are running the latest firmware version.

 

[jthorpe]

Well I upgraded again and made some changes and it's working better for now. Ugh. Frustrating. I need to sell this one and get me something else.

 

[jackj]

I'd like to sell mine and get a new GRE but I can't afford to. From what I've read, they seem to work a lot better on digital than the Unidens. I don't have any idea what the new Home Patrol is like but I'll bet it isn't much better.

 

[welshtorg]

Jack:

Does the new firmware solve the Wake Simulcast while moving issues? What threshold are you running?

 

[jackj]

Welshtorg, I don't have any simulcast in my area yet. One is coming, all of my county and local LE / fire are switching over to the Toledo/Lucas county TRS and it will be a simulcast system. The radio seems to work about as well as it can, given it's design. My problem with Uniden is that for the first year, the radio was unusable on digital systems and that was my reason for buying it. Uniden should never have put it on the market until it worked. I don't think I will ever buy another Uniden radio for that reason.

As for solving the "Wake Simulcast while moving issues", I don't know. As I understand it, simulcast reception issues in a moving vehicle are not going to be solved by software/firmware. If the simulcast is on different frequencies then there shouldn't be any problem. If they use two transmitters on the same frequency, there will be problems with multipath and different path delays times. Those problems can't be fixed on the receive end, once the errors exceed the correction ability of the FEC there will be loss of audio.

 

[welshtorg]

Well, the Wake County component of the VIPER system is a P25 Simulcast "sub-system". The frequencies are the same throughout the county due to the shear numbers of users and available frequencies. I know that the signals are carefully timed to ensure the digital talkgroup conversations are transmitted simulaneously from each site of the Wake Simulcast area. Analog talkgroups have no problems receiving audio on the Wake sites and the same digital talkgroups are easily heard on adjacent, non-Wake, VIPER sites. Often times I have to hear Raleigh FD on the Fuquay site. If I'm in Raleigh, Fuquay is just a bit too far for great audio recepotion.

I have to agree with jthorpe, my 785 and 796 performed far better in a moble setting than my 996t when monitoring the Wake County Simulcast sites.

 

[jackj]

I don't think timing can fix the problem you are talking about welshtorg. Even if they are timed perfectly, your distance from the two towers will change as you move. That is going to cause problems with multi-path distortion as well as just plain interference between the two carriers.

I wish you good luck.

 

[welshtorg]

Wonder how the actual radio does it?

 

[jackj]

The use Forward Error Correction to recover dropped bits. I have seen no indication that my 996T uses FEC at all, probably not enough processor power. About the only thing it seems to do is to perform the parity check and come up with an estimation of it's received error rate. Also, what makes you think that the commercial radios don't have problems with simulcast systems.

 

[jthorpe]

The use Forward Error Correction to recover dropped bits. I have seen no indication that my 996T uses FEC at all, probably not enough processor power. About the only thing it seems to do is to perform the parity check and come up with an estimation of it's received error rate. Also, what makes you think that the commercial radios don't have problems with simulcast systems.

Well, I have an XTL2500 in my patrol car and an XTS5000 portable and I never ever have issues with either one of those radios but at the same time, the scanner sounds HORRIBLE.

 

[jackj]

I don't know anything about the system(s) you work with or where you patrol in relation to your system(s) coverage but your statement supports my opinion. I really don't believe that scanners use Forward Error Correction while I know that the commercial radios do use it. Scanners seem to be engineered just good enough to sell.

Do you patrol near the boundaries between the two simulcast systems? Do the simulcast systems reuse the same transmit frequencies?