Test for P25 Decode Improvement

[osiris]

BCD436HP P25 Performance

link to system in RRDB
Bucks County Motorola Type II SmartZone APCO-25 Common Air Interface Exclusive
Sites monitored North & South Simulcast

(Bucks County Pa.)

On FM reception & decode is excellent
on NFM reception & decode is pretty good
FM seems to be somewhat better..
(Sorry, I don''t know how to get this system to show an actual link that you can click on.)
This system seems to be hard to monitor on my BCD396XT, the transmissions are a little garbled.
ON this 436 it is GREAT right out of the box. I haven't changed anything except to try FM & NFM.
So far (after 3 days) I LOVE this radio.
Bob

 

[dwlipp]

Montgomery County, MD Update

Montgomery County, MD Trunking System, Montgomery County, Maryland - Scanner Frequencies

Site Montored: Site 1
Condition Before*: More Tolerable (Decoding error rate ~45-55)
Condition After**: Good (Decoding error rate ~15-25)

*Configured for FM

**Additonal changes made to gain notable performance improvement

Firmware - 1.03.00
Squelch - 2

Under Options in the Site:
P25 Threshold - 11
P25 Threshold Mode - Manual

Again, I am still not sure why the P25 Auto Threshold Mode isn't working as it does in my 396XT but at this point I am getting performance from the 436 that matches, or occasionally even exceeds, the performance of my 396XT.

I haven't had an opportunity to try these tweaks on other Motorola Astro 3.0/4.1 systems to see if they work universally but I am suspecting that is the case.

Montgomery County, MD Trunking System, Montgomery County, Maryland - Scanner Frequencies

Site Montored: Site 1
Condition Before: Marginally Tolerable (Decoding error rate ~55-65)
Condition After: More Tolerable (Decoding error rate ~45-55)

Test configuration:

436 with Global Setting set to FM
Same system duplicated in the scanner, once configured for FM in the site and once for NFM in the site.
Scanned both with a consistent improvement of ~10 in the decoding error rate and a perceptible, but slight, improvement in perceived audio quality with the FM configuration.

396XT sitting 14" away from the 436 consistently decoding the system with an error rate ~15-25 and sounding much better than the 436; both running in the Auto mode.

396XT immediately adjusts the decoding threshold from 8 to 11 consistently; 436 never budges, always shows 8.

 

[Roveer]

I've been reading the Simulcast Digital Distostion wiki here:

Simulcast digital distortion - The RadioReference Wiki

where among other things it says:

Since we, the scanner hobbyist, are not paying really big bucks for a system that must work properly, the error correction algorithms used in the scanner to deal with this problem are not nearly as strong or as good as those used in two-way radios. This is not particularly the manufacturer's fault but rather a situational problem. To properly come up with a better algorithm for error correction, the software engineer must be able to "tweak" the code by repeated trial and error. And once it works for system 'A', will it work as well for system 'B'? Also, if the specific system that you are listening to has not been "tweaked" to the exact right specifications, this will just exacerbate the problem for the scanner user. Remember, actual systems can be adjusted properly or nearly properly and that one variable can cause us problems.

So my question is this, and I come from a point where I really only want to monitor a single P25 system so I may be unique.

Do we have the tools in our scanner to do all the possible tweaks to improve the decoding? I'm noticing in this thread (previous post before this one), that there are a few things users are trying and I'm going to try them too.

I'm just curious if we can "tweak" our systems to improve performance than that would make me happy.

I will say that after reading a thread the other night about a user who was doing side-by-side on a particular system, I put my 106 next to my 536 and boy was I dissapointed. 536 was missing entire multi-sentence broadcasts, not just delayed decoding and the difference in the audio quality was shocking. I want my 536 to be my favorite radio and I don't even mind waiting until something can improve these things. I just hope it's being looked at and that something can be done. Now I'm going to go and play with Sqelch, FM, P25 Threshold and P25 Threshold Mode. Hopefully that improves things a bit.

Roveer

 

[UPMan]

Since we, the scanner hobbyist, are not paying really big bucks for a system that must work properly, the error correction algorithms used in the scanner to deal with this problem are not nearly as strong or as good as those used in two-way radios. This is not particularly the manufacturer's fault but rather a situational problem. To properly come up with a better algorithm for error correction, the software engineer must be able to "tweak" the code by repeated trial and error. And once it works for system 'A', will it work as well for system 'B'? Also, if the specific system that you are listening to has not been "tweaked" to the exact right specifications, this will just exacerbate the problem for the scanner user. Remember, actual systems can be adjusted properly or nearly properly and that one variable can cause us problems.

The portion having to do with error correction algorithms is not true (at least it better not be). All decoding is done through code provided to us by DVSI. It is provided as object code and we have no ability to view or modify it (or provide tweaks for it past what is available through the object code interface protocol they provide). It is supposed to be exactly the same code implementation as any other licensee gets.

 

[bravo14]

Lynn Haven by me uses P25 uhf freq. Dispatch is loud units are normal voice.

Bay County, Florida (FL) Scanner Frequencies and Radio Frequency Reference

Threshold Mode is Auto
Condition before: Excellent
Condition after: Excellent

No difference in audio from FM to NFM. This was done by 4/536

 

[redburgundy]

The portion having to do with error correction algorithms is not true (at least it better not be). All decoding is done through code provided to us by DVSI. It is provided as object code and we have no ability to view or modify it (or provide tweaks for it past what is available through the object code interface protocol they provide). It is supposed to be exactly the same code implementation as any other licensee gets.

I think some people are using the word "decoding" to mean the RF detection and creation of a digital bitstream and others are using it to mean the rendering of audio from the bitstream.

 

[jhaynes25]

BCD436HP P25 Decode Improvement Memphis/Shelby County Public Safety

Memphis/Shelby County Public Safety Trunking System, Memphis, Tennessee - Scanner Frequencies
Specific site: Unknown
Condition before: Poor (NFM) 12.5 kHz
Condition After: Better (FM) 12.5 kHz
Condition After : EXCELENT (WFM) 12.5 kHz ?

P25 Waiting Time: 400ms
P25 Threshold Mode: Manual
P25 Threshold Level: 11

Above setting has drastically improved audio reception on my BCD436HP while monitoring the Memphis/Shelby County Public Safety.
Motorola Type II SmartZone

Haynes

 

[jasonhouk]

I've been reading the Simulcast Digital Distostion wiki here:

Simulcast digital distortion - The RadioReference Wiki

where among other things it says:

Since we, the scanner hobbyist, are not paying really big bucks for a system that must work properly, the error correction algorithms used in the scanner to deal with this problem are not nearly as strong or as good as those used in two-way radios. This is not particularly the manufacturer's fault but rather a situational problem. To properly come up with a better algorithm for error correction, the software engineer must be able to "tweak" the code by repeated trial and error. And once it works for system 'A', will it work as well for system 'B'? Also, if the specific system that you are listening to has not been "tweaked" to the exact right specifications, this will just exacerbate the problem for the scanner user. Remember, actual systems can be adjusted properly or nearly properly and that one variable can cause us problems.

So my question is this, and I come from a point where I really only want to monitor a single P25 system so I may be unique.

Do we have the tools in our scanner to do all the possible tweaks to improve the decoding? I'm noticing in this thread (previous post before this one), that there are a few things users are trying and I'm going to try them too.

I'm just curious if we can "tweak" our systems to improve performance than that would make me happy.

I will say that after reading a thread the other night about a user who was doing side-by-side on a particular system, I put my 106 next to my 536 and boy was I dissapointed. 536 was missing entire multi-sentence broadcasts, not just delayed decoding and the difference in the audio quality was shocking. I want my 536 to be my favorite radio and I don't even mind waiting until something can improve these things. I just hope it's being looked at and that something can be done. Now I'm going to go and play with Sqelch, FM, P25 Threshold and P25 Threshold Mode. Hopefully that improves things a bit.

Roveer

Uniden must implement circuitry at the receive end of the channel for making a finer (4 bit) estimation of the received energy.

 

[ks_scan]

I have seen some 396/996 tests on here, and I am not sure if UPMan is looking for that data or only data on x36 system. In case, here is info from my 996XT. My 536 came today and I am excited to get it up and running!

Butler County, Kansas P25 - Kansas Statewide Interoperable Communication System (KSICS) Trunking System, Statewide, Kansas - Scanner Frequencies
* Mobile Environment - Vehicle *
Butler County Simulcast - Multiple Towers
Condition before: Excellent
Condition after: Excellent
~ No Change Noted ~

Sedgwick County, Kansas P25 - Sedgwick County (Project 25) Emergency Services Radio System Trunking System, Wichita, Kansas - Scanner Frequencies
* Mobile Environment - Vehicle in Butler County (15 miles East of Andover Tower)
Sedgwick County Simulcast
Condition before: Poor (Decode not reliable, sparse with full signal)
Condition after: Poor
~ No Change Noted ~

 

[teufler]

What UPMAN suggested about changing modulation to FM mode rather than NFM has helped alot.

CHANGED MY P25 UHF, VHF, AND 800 MHZ FROM NFM TO FM. IN MY OLDER 296D, IF YOU WANTED TO PICK UP THE AUDIO ABIT, YOU WENT TO NFM. IT WAS LOUDER AND ALITLE MORE PUNCH. SO IF THAT WORKED , I JUST DID THE SAME WITH THE 396XT. UNDER MODULATION, IN SITES, THERE IS A SETTING FOR AUTO BUT I JUST OVER RODE AND PUT IN NFM. "PILOT ERROR" I GUESS. I MEAN THE 296D WAS A UNIDEN PRODUCT. ITS A TRUNKTRACKER IV, THE 396XT IS A TRUNKTRACKER IV.

IN FREESCAN YOU CAN CHANGE EACH LISTING FOR A FREQUENCY OR GO TO SCANNER, OPEN BAND PLAN. THEN SCROLL DOWN TO THE FREQUENCY RANGE AND CHANGE IT THERE. SAVE THE FILE. PROGRAM THE RADIO.

I HAVE MADE CHANGES FOR MY 800 MHZ, AND FOR 150+MHZ PUBLIC SAFETY. The waterfall sound, the underwater sound that I had become used to is gone. Simple fix, thanks..

 

[CQdeKS1E]

The 'waterfall'sound IS annoying on my bcd996T top the point of trying the tweaking of error rate, etc. Still no I havn't really improved audio significantly. I will continue exxperimenting until I get it right! Stay tuned!

 

[CQdeKS1E]

So how do I get to the screen 'band plan defaults'? Can't seemto land on that screen. Tried menu= settings= no 'band default' menu exists for my bcd996T, am I drilling down thru the menu screens correctly?

 

[jthorpe]

Viper, Simulcast. Raleigh NC
Wake County
BCD536HP most recent version of firmware.

Before - horrible and unreadable.
After - minute improvement but still bad
After - with change on simulcast from AUTO 8 to MANUAL 11. Perfect audio all over the place.

It appears that the scanner is not making adjustments in the auto mode and you can't make it default at a level like 11. That would be a good change. I noticed in auto the voltages don't change at all.

 

[CQdeKS1E]

P25

Thanks, I will try it.

 

[no8rf]

that did it. STARS control channel is 152.5475 in my area and is working as we speak. I had already set the band defaults to 7.5 mhz in an atempt to get it working. changed to FM and it is searching id's all over the place. thanks if it keeps on working. I just went to profile and band plan in sentinel and changed the 150.000/161.995 plan to FM and 7.50 which makes mine work perfect. hope it keeps working!

THANKS UPMAN YOU MADE MY DAY

So in sentinel I tried to change the band from NFM to FM but it will not stay, I exit after the profile change and click save but when I go back it's NFM again, this is 800 Mhz system TGID 37280 should I change to 7.5Mhz as well from 12, and again how do I do that in Sentinel? At times the station comes in grabbled and others clean and clear so not sure of the problem.

 

[WD4CQ]

I am a "Newbie" to Posting on the forum so please forgive any errors I make in posting Protocol;

Uniden BCD536HP
Latest Firmware as of 6/2/14
Squelch: 2

Scanning the New Bern, NC (Craven Co.) P25 Phase-1 Public Safety System

New Bern Public Safety (Project 25) System Trunking System, New Bern, North Carolina - Scanner Frequencies


Before: I could not even receive hardly anything on the above system.

Changed from NFM to FM
Changed from Auto to Manual and threshold 11

After: BIG improvement!!! Now I can scanner and listen to the above system. Before it was like it was not even there.

My HomePatrol-1 needed no changes and worked right out of the box
My BCD996XT Worked via programming no special settings
My BCD396XT Worked via programming no special settings

My BC536HP would not work right out of the box and needed:
Change that freq band from NFM to FM (per Upman's suggestion)
Change from Auto to Manual and setting of threshold 11

 

[no8rf]

I am a "Newbie" to Posting on the forum so please forgive any errors I make in posting Protocol;

Uniden BCD536HP
Latest Firmware as of 6/2/14
Squelch: 2

Scanning the New Bern, NC (Craven Co.) P25 Phase-1 Public Safety System

New Bern Public Safety (Project 25) System Trunking System, New Bern, North Carolina - Scanner Frequencies


Before: I could not even receive hardly anything on the above system.

Changed from NFM to FM
Changed from Auto to Manual and threshold 11

After: BIG improvement!!! Now I can scanner and listen to the above system. Before it was like it was not even there.

My HomePatrol-1 needed no changes and worked right out of the box
My BCD996XT Worked via programming no special settings
My BCD396XT Worked via programming no special settings

My BC536HP would not work right out of the box and needed:
Change that freq band from NFM to FM (per Upman's suggestion)
Change from Auto to Manual and setting of threshold 11

What are we changing from Auto to Manual?

 

[Ensnared]

Screen?

Memphis/Shelby County Public Safety Trunking System, Memphis, Tennessee - Scanner Frequencies
Specific site: Unknown
Condition before: Poor (NFM) 12.5 kHz
Condition After: Better (FM) 12.5 kHz
Condition After : EXCELENT (WFM) 12.5 kHz ?

P25 Waiting Time: 400ms
P25 Threshold Mode: Manual
P25 Threshold Level: 11

Above setting has drastically improved audio reception on my BCD436HP while monitoring the Memphis/Shelby County Public Safety.
Motorola Type II SmartZone

Haynes

Ok, folks, since I don't own one of these radios yet, please elaborate as to what it is I'm seeing here. Several people have posted similar readings, I suppose.

So, are these values settings/parameters on the Uniden or what?

 

[N9NRA]

system: Wisconsin Interoperable System for Communications (WISCOM) Trunking System, Statewide, Wisconsin - Scanner Frequencies (Wisconsin system for interoperable communications)

conditions before (NFM) poor
contitions after (switched to FM) Exellent
site monitored: Rib Mountain

Tried to paste a link to the RRDB in this, but might have gotten it wrong, if i did sorry folks , Addationally, i`m thinkin` on two possabilites here. One, the NFM mode is too "tight" (meaning the mode is simply too narrow for reliable decode) or two, the NFM setting/mode was really intended for if one encountered an X2 TDMA system. Another one is that somehow this was accadently set wrongly for the freq range. Just some thoughts on this . N9NRA

 

[RF23]

Ok, folks, since I don't own one of these radios yet, please elaborate as to what it is I'm seeing here. Several people have posted similar readings, I suppose.

So, are these values settings/parameters on the Uniden or what?

I believe post #1 of this thread should help answer your question.