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DSPLevelAdapt

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#1
I'm having a little trouble fully understanding how the DSPLevelAdapt setting works on Whistler's PSR-800 based scanners. The Easier to Read Pro-668/PSR800 Digital Scanner
and EZ-Scan/iScan Software Manual states that it "controls how fast the DSP adjusts to varying P25 levels. Lower values correspond to slower rates and higher values correspond to faster rates." For tweaking a scanner to process weak or distorted transmissions (from simulcast systems, for example) better, would I want to adjust this above or below the default value of 64? Searching the forums yielded multiple different threads that show people setting it to 0, 16, and above 64 (among other values), but nothing/no one has gone into detail about how this setting actually works and which value would be ideal in a situation like this (with consistency). Would anyone be able to shed some light on this, please? Thanks.
 

rwier

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#2
Little "real" information "how" these settings work. Many threads over several years as to "results". Read all posts on this old thread. May give you some insight.
 

rwier

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#3
Let me add that in my experience, the DSPLevelAdapt settings work together with the Data Decode Thresholds, to give maximum decode success. Incidentally, discovering the best settings for me took about 10 hours of trial and error, spread over about a month.

To keep any test more objective instead of subjective, use comparisons between two identical scanners, program, antenna, etc. Find the sweet spot that results in any changes to either scanner degrading the decode success of the changed scanner.
 
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#4
DSP Level Adapt

I have had my WS1080 since Sept 2014. I doubt those settings affect "reception" of Simulcast trunked systems very much out in the field. It's all a crap shoot of location and antenna and conditions. I have settled on 156 after years of trying. That seems the best response for my area. I DO notice setting it real low around 15 or 20 gives me worse results. The answer is to get a Unication G4/G5 voice pager for P25 Simulcast systems or a Motorola/Harris/RELM until Scanner makers make something that works better.
 
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#5
Same here. Depends on the system and location. I find when mobile, 16 works best for me on the majority of trunked systems I listen to, but it still suffers from LSM distortion as all scanners do. For P25 conventional, the factory 64 default works best me me. I haven't had luck with higher values.


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#6
I where hoping the setting had something to do with DMR decoding as well, but setting lowest, highest and middle didn't do anything for DMR channels. Changing ADC levels where also not affecting DMR decode one bit, neither worse or better.

My TRX-2 skips over half of the active DMR channels while scanning and at the same time listening to IF out and looking at the S symbol.

/Ubbe
 
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#7
I adjusted mine up to 96 for a bit and noticed on both my TRX-2 and PRO-668 that P25 transmissions were a lot more noisy. The decode was closer to how my PRO-651 sounds. It seemed also like it wasn't receiving P25 as well in general. Going back to 64 resolved this.
 

anelson5004

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#8
What is the best DSP and data Decode Thresholds settings to monitor the VA State Police STARS Radio System and the WV Statewide Radio Network for my Whistler TRX 2 connected by an outdoor antenna for it to be able to receive both Wytheville and Salem divisions at the same time on the VA Stars Radio System and all of the WV SIRN without missing transmissions ?

anelson5004
anelson5004@gmail.com
 
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#9
I'm not in your area but DSP level adapt of 16 and ADC and DAC of both 0 has been my sweet spot for multiple systems on my PSR-800.


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#11
I'm in South Florida now but also call NY / NJ home. Just remember that no current scanner can currently handle LSM distortion. But I found with the settings I posted I get pretty reliable reception on most Motorola systems. Harris on the other hand...I've tried numerous combinations for Miami-Dade County on my PSR-800 and it is terrible regardless when mobile. No problem when I hook it to my Yagi at the house and point it at the tower though. So YMMV.


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AggieCon

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#13
Linear Simulcast Modulation is a technology developed to overcome timing differences caused by transmitter spacing (somewhat significant) and multipath distortion (more significant). However, the scanners do not properly demodulate the signal, so they do not benefit from the timing buffer offered by LSM. If your scanner's front end is essentially identical to hardware developed long before LSM existed, perhaps it does not natively support the new technology...

I've yet to read--anywhere--a comprehensive and official documentation of the Whistler scanners' settings and functionality. Here and there, they might throw a bone. But, overall, we really don't know what does what.

Until the software coder and hardware designer get together and provide legitimate technical documentation (or do so via translator and technical writer), I think we are wasting our time attempting to establish what might or might not do something. It's likely that many of the EZ Scan settings have no affect on the scanner's operation. Time is better spent on the proper tools rather than trying to force the wrong tool to work.

I've never had success with the DSP Level Adapt setting. Programming 1 site and 1 frequency, along with low squelch are the best tips I can offer for improving P25 digital trunking performance.

Really, digital to analog converter gain is the only thing that probably matters in that section of settings. And you want that to be low so there isn't as much of a volume difference between analog and digital broadcasts.

I'm not sure if the ADC does anything. At least I've never noticed the scanner behave differently. If it does amplify the analog signal variably, it would be important to know how this is done. Some methods could make things worse by distorting the signal. A good DSP is much more sensitive than our ears. In two way digital radios, the analog to digital converter of the vocoder is what turns the caller's spoken word into a digital signal (which is later compressed by the vocoder). The radios have a ADC setting to account for user variation in holding the radio, how loud they talk, etc. I don't know what GRE/Whislter used as a starting point for their scanner, but I wonder if someone read about a ADC setting for the vocoder and left it in even though it doesn't apply to a scanner.

Keep talking this subject up and perhaps they will release some official information about what exactly these settings do and how, detailed and comprehensively, they modify the scanner operation.
 
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