Test for P25 Decode Improvement

[ecarvalho]

I will try that this evening - thank you KE4ZNR

I have also changed the link to my live dropbox since the "date" folder will change tomorrow, I've shared the root folder of my recordings instead:

https://www.dropbox.com/sh/i1vrnh4zb5io44b/AAA9z7Opd1T1ZGzS6eRp0hCaa?dl=0

Note: I am on HOLD at Loudoun County for the moment.

 

[teknishun]

This is an old thread but I think my 536 is having audio issues on our Loudoun County (Virginia) P25.
We have good signal and all but audio is garbled and seems the radio is not keeping up / following the conversations as I only get bits and pieces of transmissions.

You can hear my most recent recordings here:
DROPBOX SHARED LINK:
https://www.dropbox.com/sh/i1vrnh4zb5io44b/AAA9z7Opd1T1ZGzS6eRp0hCaa?dl=0

For now, I will try switching to FM on a channel (Dulles Dispatch) which is the worst at this time and later report back.

Note: If there is any other fix please let me know.
Firmware: 1.10.02

I have the exact same problem here in Houston, Texas area with the digital P25 trunking.

I have a hunch your problem is caused by simulcast distortion - multiple towers all with
identical channels and all transmitting simultaneously. The scanner can receive more than
one of these transmissions. It IS possible in other words to have an antenna that is "too good."

I run my 536HP with the digital AGC turned ON because if I don't there are some units that
transmit way too loud and others you can barely hear at all. The volume varies from site
to site and from one transmission to the next.

Welcome to the world of digital! Dang, how I long for the "old days" of analog scanners
that used crystals. (sigh)

 

[ecarvalho]

KE4ZNR
It appears audio improved with digital AGC turned off. I need to listen to it a bit more. Thank you.

Upman
Switching Loudoun County (VA) DULLES DISPATCH to FM made audio worse. I had to go back to NFM.

teknishun
Perhaps you are right and I am thinking of maybe turning on the attenuation for this particular department.

So far, audio improved without digital AGC (I dont seem to have loud units here) but I still fill I am missing out the entire conversation getting just bits of transmissions. Sometimes just a transmission calling the time which didnt precede with anything at all. Note I am HOLDING the channel so I should've gotten some transmission before someone called the time.

For now I will attempt activating ATT and listen.

As before, I continue to allow sharing my automated recordings for anyone to evaluate if interested.
Here is again the dropbox link:
(go to the Loudoun County folder for the most recent recordings)
https://www.dropbox.com/sh/i1vrnh4zb5io44b/AAA9z7Opd1T1ZGzS6eRp0hCaa?dl=0

E

 

[ecarvalho]

Update:
I noticed attenuation lowered my signal tremedously to a single bar. So I decided to leave it out (full bars).
The most recent change as of 20:45 ET, was to move the 536 away from a network hub (it was on top of it).
I wonder if it was causing some sort of interference. I will listen to the next transmissions.

Dropbox of live recordings (real time): Scanner is HOLD on Dulles Dispatch channel. Digital AGC off. NFM.
https://www.dropbox.com/sh/i1vrnh4zb5io44b/AAA9z7Opd1T1ZGzS6eRp0hCaa?dl=0

Side note:
I keep my 536 updated with the Sentinel software 1.06.00. Firmware is the most recent 1.10.02.
I still think I am missing out on all transmissions. (radio not following conversations)

 

[ecarvalho]

I'm working on manually adjusting the P25 threshold for this. Looks like setting at 9 gives me less errors and sounds better. Error rate was previously going up to 80+ now reaching 66 at "9". The higher I go the worse it gets.

 

[policefreak]

I have found that while a threshold of 9 or even 10 sounds cleaner, the radio tends to miss more transmissions at this level than at a more open threshold such as 7 or even 6. 5 seems to be too low on most systems as voice breaks up and entire transmissions are garbled even though everything comes through.

 

[ecarvalho]

So I have left the Dulles Dispatch at threshold 9 Manual (errors are in the low 30s) - while everything else 8 Auto.
For instance, the Virginia State Police "VSP Fairfax 1 and 2" are clean and loud with 8-Auto. So another funky fact is that today after 8:00 am, Dulles Dispatch changed from P25 to PT0 and PT1. No clue why. I confirmed that with my PSR-800 - which there shows D2.
Something changed and I dont really know why.

I have the recordings stopped for now. Using the scanner own speaker as I have to work this evening from home.

 

[darunimal]

So are you saying [http://www.radioreference.com/apps/db/?sid=6524] or Metropolitan Washington Airports Authority (Project 25) Trunking System, DCA and IAD Airports, Virginia - Scanner Frequencies because Loudon is listed as Phase II or did MWAA changed to Phase II from Phase I (The Dulles Dispatch without reference is confusing me a bit. Digital AGC will make the incoming signals' highs: higher and lows also higher, which will cause more decode errors, best if left OFF for most Phase I and Phase II systems. That's why it's also appreciable to use Manual instead of Auto, it keeps the highs and lows from swing and right where they need to be, to be decoded. I would suggest 8 if your still in the 30's for errors and leave it there for between 15-30 minutes and then check decode errors if higher move to 10 and then check errors again.

 

[policefreak]

Based on Dulles going from displaying P25 to PT0 or PT1 it sounds like they just switched to phase 2 TDMA.

 

[teknishun]

KE4ZNR
It appears audio improved with digital AGC turned off. I need to listen to it a bit more. Thank you.

So far, audio improved without digital AGC (I dont seem to have loud units here) but I still fill I am missing out the entire conversation getting just bits of transmissions. Sometimes just a transmission calling the time which didnt precede with anything at all. Note I am HOLDING the channel so I should've gotten some transmission before someone called the time. E

I would have to agree about turning the digital AGC off in the system you are monitoring.
It does seem to improve the audio quite a bit over the way it was acting before.

I need to listen a bit more myself before judging.

One thing I have discovered about digital P25 trunking - just because it works fine
right now does not mean it will work that well later. You can turn the scanner off
and walk away without changing any settings at all. The next time you turn the
scanner back on the digital may or may not work as good as it did last time.

I do not blame the scanner for this. There is not a consumer police scanner on the
market, of any brand, that can handle simulcast all that well. It is hit or miss.

It all depends on 3 things: 1) What you are listening to 2) the location of what you
are listening to (i.e. which site) and 3) Your location where you are doing the listening.
If you change any of those 3 things your experience can be better or worse.

I'll take a scratchy analog signal over a "good" digital signal anytime.
At least you can plainly hear the analog, even over the static.
I never - ever - had as many reception problems with the analog trunking
as I do now with the P25 digital. But that's progress!

teknishun

 

[CPerk]

Having an Issue with Hanover County Virginia Phase I system,(P25)
with the Phase 3 of DMR pre release the audio quality breaks up and very choppy, I have my threshold on Manual n set on 7


any settings I need to change other than what you have listed above

 

[ecarvalho]

I am pleased to announce that I have better reception of the Loudoun County P25 Phase II system since I changed the P25 settings to 7-MANUAL. Modulation is set to ALL / AUTO. Probably working in NFM.
I have also upgraded the scanner firmware to version 3 of the beta DMR firmware. I am scanning through the only DMR system I found around here (United Airlines O Hare / Dulles. Nothing has been heard but I am not worried about it yet. For now, glad to have better reception and low errors on my favorite system.
I have private message the owner of the Dulles Sherrif / Fire scanner feed from broadcastify a few times asking which scanner or settings he was using but received no reply. It is OK - I figured it out myself which makes me happy. I hope this helps others with similar issues.

PS.: Changing to FM didnt help me.

 

[freqhopping]

I am pleased to announce that I have better reception of the Loudoun County P25 Phase II system since I changed the P25 settings to 7-MANUAL. Modulation is set to ALL / AUTO. Probably working in NFM.
I have also upgraded the scanner firmware to version 3 of the beta DMR firmware. I am scanning through the only DMR system I found around here (United Airlines O Hare / Dulles. Nothing has been heard but I am not worried about it yet. For now, glad to have better reception and low errors on my favorite system.

Loudoun has always worked fine for me with the auto settings.
You may need to actually be at the airport to hear the United system. I've know their past systems have had very limited range.

 

[ecarvalho]

Thank you freqhopping. Are you able to use DMR in your scanner? If yes, could you see if hear anything? Yes I will try taking the radio to Dulles and see if I pick up anything. I'm close and I thought I should be able to hear it. I can pick up the tower on the airband. But maybe this DMR system is low power...?

Loudoun has always worked fine for me with the auto settings.
You may need to actually be at the airport to hear the United system. I've know their past systems have had very limited range.

 

[freqhopping]

Thank you freqhopping. Are you able to use DMR in your scanner? If yes, could you see if hear anything? Yes I will try taking the radio to Dulles and see if I pick up anything. I'm close and I thought I should be able to hear it. I can pick up the tower on the airband. But maybe this DMR system is low power...?

DMR is working fine for me. Went by the airport on the way home from work today and the United system was working fine. Lots of activity. In five minutes or so I logged 14 TGs with 4230017 being a new one not in the database.

 

[BCasto]

For some reason(s) some TGs on my BDC996XT have the loud hammer sound (growl if you prefer) and some don't. It can last for a couple seconds. It is such an annoyance it makes monitoring difficult. Is it a matter of adjusting P25 settings or is it something else? Appreciate your help.

 

[teknishun]

For some reason(s) some TGs on my BDC996XT have the loud hammer sound (growl if you prefer) and some don't. It can last for a couple seconds. It is such an annoyance it makes monitoring difficult. Is it a matter of adjusting P25 settings or is it something else? Appreciate your help.

I have that problem occasionally when I am mobile with the 996XT. For me it has always been caused by being in very close proximity to another tower site that I am not tuned to. The nearby tower is so strong that it overrides the front end of the radio and the control channel bleeds over onto the audio.

Another reason is that the frequencies in the site of interest you are listening to have changed.
Take a look at Radio Reference for your site. All you need to program is the red and the blue control freqs and the alternates. You do not need the voice channels. It is possible that a voice channel has now become a control channel.

teknishun

 

[cellphone]

It could be caused by your phone too. Next time you hear the sound, grab your phone and move it away to see if the sound goes away.

 

[BCasto]

hammer sound

Thanks for the suggestions... I will try them out. I am glad there are smart people on this forum.

 

[BCasto]

Hammer noise

I changed the systems to only include the control channels (locked out the others) and moved all other electrical equipment (phone included) away from the scanner. The antenna is in the attic, far away from other things too. So far I am still getting the noise at the start of many transmissions. I looked around some more here and am wondering If all my setting are good.

I am monitoring Wake Co. NC Simulcast. Am using ProScan. I have it set up as a standard Motorola system, ID Search, Decimal ID format, Analog and Digital End Codes, AGC Analog and AGC Digital, Fleetmap custom, auto modulation, P25 wait time of 400ms, 0 settings for Analog/Digital response time - reference gain - dynamic range, P25 low pass filter is off, C-Ch Output is turned off when Proscan talks to the 996XT, and each TG has an audio type of "all" (not specifically digital or analog but both). Should I change any of this?

Not sure if this is related, but sometimes when stopped on a TG, the voice has silent breaks in it. I will hear the voice and midstream the voice just stops for a few seconds, then resumes. The scanner stays on the TG but the voice disappears.

Thanks for your help.