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P25 Decode of conventional system

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rbhtxk

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Greenville, Texas PD has a new VHF Hi band freq that they have moved all their voice traffic to. It was mixed analoug-P25, but in the last week has gone all P25. SO:
I got a new BCD396 and programmed it up (took a while) and was not able to get the radio to decode the p25 traffic, until this evening.

Today while playing with the mode setting, I accidentally set the modulation type to AM and began to hear all the voice traffic (I can still tell the radio is in the AM receive mode); I hear all the voice traffic FB no with no fading or dropouts just the AM ringing from an FM style transmission. Placing the radio in auto for modulation type, narrow FM, or FM does not decode the P25 traffic but give me the warbling tones of P25 format. P25 traffic on this frequency is only audible via AM.

I am sure that there is a setting for P25 reception, but where do I go and what's a good place to start?

Thanks...

Rob...
 

seamusg

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rbhtxk said:
Greenville, Texas PD has a new VHF Hi band freq that they have moved all their voice traffic to. It was mixed analoug-P25, but in the last week has gone all P25. SO:
I got a new BCD396 and programmed it up (took a while) and was not able to get the radio to decode the p25 traffic, until this evening.

Today while playing with the mode setting, I accidentally set the modulation type to AM and began to hear all the voice traffic (I can still tell the radio is in the AM receive mode); I hear all the voice traffic FB no with no fading or dropouts just the AM ringing from an FM style transmission. Placing the radio in auto for modulation type, narrow FM, or FM does not decode the P25 traffic but give me the warbling tones of P25 format. P25 traffic on this frequency is only audible via AM.

I am sure that there is a setting for P25 reception, but where do I go and what's a good place to start?

Thanks...

Rob...
If it's conventional it's not a trunked system. If it's p25 voice set it for FM and it should work as conventional NOT a P25 system, unless it has a control channel with voice freqs and talk groups it' not a trunked system A P25 or Project 24 Standaed system is a trunked system with a 9600 bps control channel, APCO25 voice is a different item. APCO P25 voice can be used on any conventional channel, with out a Project 25 Standard System.
 

rbhtxk

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Its safe to say that this is a conventional channel that uses APCO P25 voice; it is not a trunked system. Does anyone know the proper settings for the reception of APCO 25 voice on the BCD396? It does not seem correct to have this channel set of AM modulation to properly decode?
Rob...
 

hiegtx

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rbhtxk said:
Greenville, Texas PD has a new VHF Hi band freq that they have moved all their voice traffic to. It was mixed analoug-P25, but in the last week has gone all P25. SO:
I got a new BCD396 and programmed it up (took a while) and was not able to get the radio to decode the p25 traffic, until this evening.

Today while playing with the mode setting, I accidentally set the modulation type to AM and began to hear all the voice traffic (I can still tell the radio is in the AM receive mode); I hear all the voice traffic FB no with no fading or dropouts just the AM ringing from an FM style transmission. Placing the radio in auto for modulation type, narrow FM, or FM does not decode the P25 traffic but give me the warbling tones of P25 format. P25 traffic on this frequency is only audible via AM.

I am sure that there is a setting for P25 reception, but where do I go and what's a good place to start?

Thanks...

Rob...
Rob, is 158.73750 the frequency you are trying to hear?
158.73750 - 153.89750 - WQFB680 - RM - 346 DPL - Police Dispatch (new, mixed analog and digital) - APCO-25

If you left the DCS code (346) in the channel when they went to all digital, that may be why you weren't hearing them. Digital does not use PL/CTCSS or DCS codes. For that frequency, change it to "none". Or, you can program the channel a second time without the code, labeling it as P25. The 996 has a channel setting to designate analog only or digital. The 396 does not. Flipping the channel to AM probably wiped out the DCS code. With that frequency, probably the correct setting will be narrow FM (FMN). Try that or 'Auto', but be sure & set the tone/code option for that channel to "None". (If it works, but audio sounds wek, then try FM.)

Note that TxDPS is converting, region by region, from analog to APCO-25 (digital) on conventional frequencies. If you take a look at the DPS frequency chart, it looks like a bunch of channels. But, if you look closer, you'll see that most of them are reused over & over & over..... Some are still used analog in regions that have not converted, but are digital in others.

You are in DPS Region 1, as I am in Dallas. From what I've heard, that may be the last one to convert. However, parts of Region 6, just to your south, have converted some bases & repeaters to digital. What I have done is created a digital group for DPS, labeling it APCO-25, within my TX DPS system file. It has all the frequencies in it, without any PL or DCS codes. The other groups have PL or DCS codes if any or listed for specific base stations, repeaters, or mobile applications.
 

DaveNF2G

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The short answer is this:

To receive conventional P25 digital transmissions, program the frequency in FM mode.
 

ctrabs74

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DaveNF2G said:
The short answer is this:

To receive conventional P25 digital transmissions, program the frequency in FM mode.
I have the similar thing going on with a local PD freq in Pa. (outside of Philadelphia). My local department (West Chester) operates on 500.4125 and 500.5125; they are analog at present, but are in the process of switching over to P25. The only hint of a digital switchover are "bursts" of what I think is digital noise that pops up with a PL of 67.0 (normal PL is 97.3). I'll try your suggestion above and see what happens.
 

slicerwizard

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rbhtxk said:
I am sure that there is a setting for P25 reception, but where do I go and what's a good place to start?
Did you set the P25 decode level for the system?

Hold on the conventional channel, press Func-ScrollDown (press scroll knob down while holding Func key in) to get to the P25 settings.
You'll probably see "0 AUTO"; use Func-ScrollCW/CCW to set it to "8 AUTO" or so and see how it works.
 

nexus

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My guess would be the decode level too. If it's way off you won't hear anything, or you'll only hear gerberlling, or digital noise. Gotta play with it while they're talking to tune in the best signal.

The 396T will automatically decode APCO25 regardless if it's conventional, or trunking. If they're using a repeater or a simplex frequency just program it in the scanner into a memory channel and let it go. If the signal that comes across is APCO25 then P25 will flash and it'll be digital voice. If it's not APCO25 then you'll just hear analog voice come across. It's that simple.

but if they're using P25 and you don't hear anything, the only thing it could be is the digital tuning is off and needs to be adjusted. Follow your manual on how to tune it.
 

ctrabs74

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nexus said:
The 396T will automatically decode APCO25 regardless if it's conventional, or trunking. If they're using a repeater or a simplex frequency just program it in the scanner into a memory channel and let it go. If the signal that comes across is APCO25 then P25 will flash and it'll be digital voice. If it's not APCO25 then you'll just hear analog voice come across.
So, how does it happen that a system that's testing it's analog freqs for a digital conversion comes across as "digital noise" at 67.0 PL? Is that just system testing, or is it possible that once the freqs go digital, that's all I'm going to be able to hear? The system I'm talking about is going to be using Motorola radios, so I'm guessing it's going to be a P25 system.
 

sflmonitor

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Also keep in mind that if you have the tone setting set to "search", the 396 will NOT decode P25 and you will hear digital noise.
 

seamusg

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ctrabs74 said:
So, how does it happen that a system that's testing it's analog freqs for a digital conversion comes across as "digital noise" at 67.0 PL? Is that just system testing, or is it possible that once the freqs go digital, that's all I'm going to be able to hear? The system I'm talking about is going to be using Motorola radios, so I'm guessing it's going to be a P25 system.
Putting in a PL will stop the scanner from receiving the P25 voice. Digital does not use PL.
Conventional freqs are not a system only trunked are systems..
 

ctrabs74

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JoeH said:
Also keep in mind that if you have the tone setting set to "search", the 396 will NOT decode P25 and you will hear digital noise.
Okay, then I'll turn the tone setting to "OFF" and see what happens...
 

rbhtxk

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Turning off DCS= Works

OK, if you have the dcs or pl turned on on the 396 for a conventional frequenct, it will not decode P25 standard voice transmissions. I re-programmed the freq without the dcs and it works. However, I still get a little digi hash before the raido synchs up, on AM modulation, no hash all voice; go figure. Thanks to all for the info on getting the radio to work.

Rob
BCD396T PRO97 PRO26 and many, many others.
 

seamusg

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rbhtxk said:
OK, if you have the dcs or pl turned on on the 396 for a conventional frequenct, it will not decode P25 standard voice transmissions. I re-programmed the freq without the dcs and it works. However, I still get a little digi hash before the raido synchs up, on AM modulation, no hash all voice; go figure. Thanks to all for the info on getting the radio to work.

Rob
BCD396T PRO97 PRO26 and many, many others.
Try FM It should work.
 

hiegtx

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rbhtxk said:
OK, if you have the dcs or pl turned on on the 396 for a conventional frequenct, it will not decode P25 standard voice transmissions. I re-programmed the freq without the dcs and it works. However, I still get a little digi hash before the raido synchs up, on AM modulation, no hash all voice; go figure. Thanks to all for the info on getting the radio to work.

Rob
BCD396T PRO97 PRO26 and many, many others.
I sent you some additional information in response to your PM.

Now that it's working, try the digital decoding tweaks suggested by some of the others. Also, make sure that your scanner has the latest firmware, which is 1.11.03. Depending on date of manufacture, and how long it was in your dealer's inventory before you got it, you might need to update.

Uniden's notes on tweaking the decode rate are on their download page for the 396.
 
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