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DSD+ preformance on Harris P25 phase II systems, please reoprt decode quality.

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#1
Hi,

I am looking for feedback on anyone monitoring a Harris P25 phase II systems. Can you provide feedback on your audio decode success, or lack of.
 
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#2
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#3
I have this post here:

https://forums.radioreference.com/threads/dsd-pii-motorola-vs-harris-results.388686/

It shows my setting on the Harris system, problem is there are so few clear transmission it's hard to adjust setting on the fly. I include the link so you can see my setting. I rephrased the post here to focus on the Harris systems.

I have tested same setup on a bunch of Moto systems and the decode is perfect on those. I have sent a raw sample to the DSD+ team of the Harris system but that was a while back and they must be tied up on other things.

Have you tried different setting for the Harris system you can monitor?
 
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#4
I have this post here:

https://forums.radioreference.com/threads/dsd-pii-motorola-vs-harris-results.388686/

It shows my setting on the Harris system, problem is there are so few clear transmission it's hard to adjust setting on the fly. I include the link so you can see my setting. I rephrased the post here to focus on the Harris systems.

I have tested same setup on a bunch of Moto systems and the decode is perfect on those. I have sent a raw sample to the DSD+ team of the Harris system but that was a while back and they must be tied up on other things.

Have you tried different setting for the Harris system you can monitor?
Mine is the same. It wouldn't matter if I used the -f1 switch either. Still has clipping. DMR Provoice, Con+ , Cap+, and P25 PI don't have this clipping issue.
 
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#6
EDIT: sorry I missed that you are referring to a Phase II system. However perhaps my info is of some use.

https://www.radioreference.com/apps/db/?sid=8161 [ not phase II ]

Here are my results:

- PSR 600 ► all garbled, not usable at all, works great on other P25 C4FM systems

- 396T ► it works but voice quality is not great, works great on other P25 C4FM systems

- DSD+ ► works fairly well but not as good as other P25 C4FM systems

- Unitrunker V2 ► does not work at all, but is fine on other P25 C4FM systems [also CC decode is very poor]

UT Ver 2 shows the Harris system as a CQPSK modulation scheme.
There are no other CQPSK systems here that I can use for a comparison.

I feel at this point that the issue is with systems that use CQPSK modulation scheme.
[cannot be certain of this]

Mike
 
Last edited:
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#7
EDIT: sorry I missed that you are referring to a Phase II system. However perhaps my info is of some use.

https://www.radioreference.com/apps/db/?sid=8161 [ not phase II ]

Here are my results:

- PSR 600 ► all garbled, not usable at all, works great on other P25 C4FM systems

- 396T ► it works but voice quality is not great, works great on other P25 C4FM systems

- DSD+ ► works fairly well but not as good as other P25 C4FM systems

- Unitrunker V2 ► does not work at all, but is fine on other P25 C4FM systems [also CC decode is very poor]

UT Ver 2 shows the Harris system as a CQPSK modulation scheme.
There are no other CQPSK systems here that I can use for a comparison.

I feel at this point that the issue is with systems that use CQPSK modulation scheme.
[cannot be certain of this]

Mike
Makes me think DSDPlus should have seperate P25 modes one for C4FM and other for CQPSK. I don't know what that means for TDMA.
 
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#8
I did not realize P25 had two different modulation modes? I would think TDMA (phase II) would have the same modulation method for compatibility. Does a Motorola radio not work on a Harris system if they are both P25 TDMA, they must.
 
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#10
I don't know for certain, have been searching the net for more technical info.
Would like to find out why CQPSK voice quality is so poor.
Possibly they don't have a very good CQPSK raw recording to develop from. If I had the proper scanner to do it I would send Oklahoma City's CQPSK raw audio. They want it recorded from a scanner. I don't own a scanner. I would give them a high bitrate clear recording without any audio enhancements. must be as flat as it is going into the antenna.
 

GTR8000

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#11
Possibly they don't have a very good CQPSK raw recording to develop from. If I had the proper scanner to do it I would send Oklahoma City's CQPSK raw audio. They want it recorded from a scanner. I don't own a scanner. I would give them a high bitrate clear recording without any audio enhancements. must be as flat as it is going into the antenna.
That's not accurate. The DSD+ author requires high quality raw recordings made with DSD+ itself, created by pressing the R key while monitoring a signal; there is never any scanner involved in the process.
 
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#12
That's not accurate. The DSD+ author requires high quality raw recordings made with DSD+ itself, created by pressing the R key while monitoring a signal; there is never any scanner involved in the process.
Well okay then. Something apparently isnt right. Constant clipping decodes on CQPSK. Don't know if they relied on a user provided recording or they have a P25 PII TDMA nearby. I hope noone is trying "pretty" up the raw audio.
 

GTR8000

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#13
Well okay then. Something apparently isnt right. Constant clipping decodes on CQPSK. Don't know if they relied on a user provided recording or they have a P25 PII TDMA nearby. I hope noone is trying "pretty" up the raw audio.
Frankly, it's a Harris issue, not a DSD+ issue. Harris simulcast systems are notoriously difficult to decode no matter what you're using (save for perhaps an actual system radio). I have a strong Harris P25 H-DQPSK signal nearby that is troublesome to decode with anything other than an APX radio. Great RSSI on the signal, but awful signal quality. It even looks awful on the scope as compared to a Motorola H-DQPSK/LSM signal. It has been reported many times by many users listening to Harris P25 systems that this is the case even with the SDS series scanners, which excel at demodulating P25 simulcast.
 
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#14
Too bad about the Harris system. I wonder how it sounds on a professional radio?

C4FM systems sound not too bad, unless the signal is weak and noisy.
 
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#17
I sent a DSD+ raw audio into the DSD+ team, maybe just one of the many thing they have to work on I guess.

That's not accurate. The DSD+ author requires high quality raw recordings made with DSD+ itself, created by pressing the R key while monitoring a signal; there is never any scanner involved in the process.
 
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#18
This is interesting, my screen shot on post 16 is from Unitrunker here is the DSD+ screen shot, it's clipping? I am using a good quality RTL a N3 thumbsat. I am going to try different gain settings.


1558910785013.png
 
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#19
I tried all kinds of gain setting (0,1,5,10,20,40) and it remains the same waveform in DSD+. I did note when I set gain to 20.0 it displays 19.7 on screen and when set to forty it display 40.2 onscreen. I wonder if it's a bit of a bug?
 

GTR8000

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#20
Are there any unencrypted talkgroups on that system? Database indicates they're all strapped secure.

If you're within range of any of the Bell MTS sites, take a look at the waveform for those systems using the same setup, and compare to the Winnepeg system. Bell MTS is a Motorola ASTRO 25 system. I suspect that you'll see a noticeable difference in the signal quality, as the waveform will look more consistent and "cleaner".
 
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