The official "I want LSM to work properly in my scanner" thread

[slicerwizard]

OP25, UniTrunker, SDRTrunk, and DSD+ all do trunking. For simulcast, OP25 is your best option, followed by SDRTrunk.

So not DSD+? I ask because DSD+ is all I'm using for P25 simulcast and it's working fine for me.

This is the last one I bought: http://www.amazon.com/Receiver-RTL2832U-Low-Cost-Compatible-Packages/dp/B015DN4DP6

Gah. I would never recommend the cheesy units with MCX connectors these days. IMO, BNC or SMA would be a better choice.

Even though it's useless to me at present, the devs of SDRTrunk seem to have developed a solid vocoder with great audio

I could be wrong, but I thought Denny used an existing MBE library?

 

[AggieCon]

What version of DSD+ do you use? I have 1.101 and it doesn't perform nearly as well as OP25 and SDRTrunk on the Phase 1 simulcast systems around me. Does DSD+ actually support CQPSK modulation?

I have a limited budget, so I use the cheapest device that will work. I've had no problems with these; the one expensive NooElec dongle I have is no better than the others. Sure, BNC would be nice, but $10 is what works for me. I will gladly accept grants for better equipment or software.

 

[natedawg1604]

.... Does DSD+ actually support CQPSK modulation?

....

I am 99% confident it does not. There is a large simulcast system in my area with lots of simulcast distortion on hardware scanners; DSD+ 2.10 cannot decode this system properly, I get lots of simulcast distortion artifacts, just like you would get on hardware scanners. However, OP-25 and SDRTrunk properly decode this system with zero simulcast distortion.

The documentation for DSD+ 2.5 claims it handles simulcast (without any details whatsoever), but I am quite confident it does not at the present time.

 

[DSheirer]

I could be wrong, but I thought Denny used an existing MBE library?

Andy, I coded the JMBE library (IMBE codec) from the spec, but peeked several times at mbelib to see how they coded some of the algorithms.

cheers,
Denny

 

[slicerwizard]

What version of DSD+ do you use? I have 1.101 and it doesn't perform nearly as well as OP25 and SDRTrunk on the Phase 1 simulcast systems around me. Does DSD+ actually support CQPSK modulation?

I use the latest - 2.10; in conjunction with FMPA and/or FMP24, it's handling simulcast fine. Most of the systems here are Motorola, but some are Harris and at least one is from Cassidian.

I have a limited budget, so I use the cheapest device that will work. I've had no problems with these; the one expensive NooElec dongle I have is no better than the others. Sure, BNC would be nice, but $10 is what works for me. I will gladly accept grants for better equipment or software.

Wouldn't we all!

I found the MCX versions to have reliability issues - not so much with the dongles themselves, but with the pigtails needed to connect to BNC-equipped coax, as well as the included coax and magmount antennas. So I paid for a couple for the $12 MCX dongles and then for the rtl-sdr.com low-drift units that eventually had to replace them...

I am 99% confident it does not. There is a large simulcast system in my area with lots of simulcast distortion on hardware scanners; DSD+ 2.10 cannot decode this system properly, I get lots of simulcast distortion artifacts, just like you would get on hardware scanners. However, OP-25 and SDRTrunk properly decode this system with zero simulcast distortion.

The documentation for DSD+ 2.5 claims it handles simulcast (without any details whatsoever), but I am quite confident it does not at the present time.

So essentially, you're calling the developers liars or incompetent...

I asked some of the local experts here where the bad RX locations were for our local systems, i.e. where scanners (various models) had a hard time. The response was simply "everywhere", so apparently I don't live in some simulcast nirvana. Despite that, DSD+ is decoding CCs and clear Phase I voice, where present, on all of these systems, most of which are simulcast:

P25, 00001.001, "London PS"
P25, 1484F.36D, "GTAA"
P25, 148DE.00A, "Durham Region PS"
P25, 458AD.227, "Monroe/Ontario County"
P25, 458AD.229, "Genesee County, Batavia"
P25, 458AD.22A, "Orleans County, Albion"
P25, 8D45F.36F, "RCMP"
P25, BEE00.1AC, "MetroLinx"
P25, BEE00.39E, "Hamilton PS"
P25, BEE00.3C2, "Toronto PS"
P25, BEE00.444, "Halton Region PS"
P25, BEE00.4F1, "Niagara County PS, Lockport"
P25, BEE00.4F8, "Peel Region PS"
P25, BEE00.644, "Chautauqua County PS"
P25, BEE00.64C, "York Region PS"
P25, BEE00.882, "Toronto Hydro"

At your request, I uploaded detailed testing logs here: P25-Reception-Testing.zip - Sabercat File Hosting

The detailed console logs show P25 CC decoding on MetroLinx (UHF simulcast) and Toronto PS (700 simulcast) that is nearly perfect. The Toronto log shows some errors at the start - where FMP24 was auto center tuning - but once the signal was tuned correctly, the errors went away. That doesn't look like "doesn't handle simulcast".

The CC log for Peel Region PS (800 simulcast) shows some errors, but I'm not really surprised, considering that the system is somewhat distant and a big chunk of the region is in a hole, so the signal's fairly weak and it's competing with the local Telus iDEN sites and I wasn't using an 800 MHz antenna, yadda yadda. Despite that, by my calculations, 10553 of 10812 control channel messages were properly decoded. That's a 97.6% decode rate. Again, that doesn't look like "doesn't handle simulcast".

Is there room for improvement? I would say definitely. But to claim DSD+ "doesn't handle simulcast" is frankly uncalled for. DSD+ 2.5 added P25 control channel decoding and simulcast support. Before 2.5, I could sit a block away from a simulcast site, parked on a system voice channel and get no audio out of DSD+. Meanwhile, I get audio out of 2.5 and up from these systems wherever I set up my laptop, including mobile operation - mobile as in actually driving around town.

So that's my two cents on the topic...

Andy, I coded the JMBE library (IMBE codec) from the spec, but peeked several times at mbelib to see how they coded some of the algorithms.

Rawg. Having fun with AMBE?

 

[AggieCon]

I based my DSD+ observations on the latest free version. By the way, it's been awhile since that was released. I wonder if 2.5 will be released freely.

The best evidence would be a simultaneous comparison between the three applications. Also, I'd be careful about basing voice success off of control channel decoding.

If you upload that file to something like Dropbox or the RR attachment function, I'll take a look.

If DSD+ really does legitimately support simulcast now, that's awesome. It's good to hear that some are actually putting the effort into it.

 

[slicerwizard]

Also, I'd be careful about basing voice success off of control channel decoding.

Why? Is there something different about Phase I voice channels?

If you upload that file to something like Dropbox or the RR attachment function, I'll take a look.

It's already uploaded and it includes voice samples.

 

[Medziatkowicz35]

Ok. So what sdr trunk should I buy for my area of the northern wv panhandle? The digital systems are in Jefferson County Ohio and Ohio county wv both are p25 simulcast and trunked.

 

[mk262]

slicerwizard, semi OT but what kind of antenna are you using on those simulcast sites?

 

[mtindor]

If DSD+ really does legitimately support simulcast now, that's awesome. It's good to hear that some are actually putting the effort into it.

There is no IF. DSDPlus 2.10 / 2.8 and maybe even 2.5 absolutely DO support LSM. I'm using DSDPlus 2.10 to monitor / voice follow a 9-site simulcast without any issues whatsoever, using FMP24/FMPA and DSDPlus.

All of my scanners / SDR stuff are connected to the same Stridsberg multicoupler and single antenna system. My PSR-500 / PRO-197 cannot even begin to decode the same system. My BCD436HP does a better job but anywhere good enough from my current location.

DSDPLus [at least when using FMPA and FMP24 to control the Airspy and RTL] is 100% decode, and it does a pretty damned good job even on weaker signals. I'm tickled pink by DSDPlus' performance.

I should also state that Denny's SDRTrunk also handles LSM and does a superb job monitoring the same system. Of course, I don't need to tell anyone that Max's OP25 does -- but it does

Mike

 

[mtindor]

What about trunking? Jefferson County Ohio, and Ohio county,wv are p25 simulcast and trunked

SDRTrunnk will work fine on the Jefferson Co IP simulcast as well as any SIRN stuff. Phase II talkgroup activity is not currently seen on either system, and will probably remain like that for the foreseeable future. Stop worrying about Phase II monitoring if you've got no Phase II to monitor.

Mike

 

[AggieCon]

Why? Is there something different about Phase I voice channels?

Yes, you have to decode voice. The presence of and quality of the voice decoder is very important. By your metric, UniTrunker does a fabulous job with P25 digital voice and is the best solution for anyone wanting to listen to a digital system. Notably, most end users will base performance on the audio quality.

 

[AggieCon]

Just because you are able to get good simulcast digital audio off of a certain device or software, doesn't necessarily mean simulcast CQPSK is supported. As you somewhat allude to, I can take a certain consumer hardware scanner to certain locations and get perfect voice decode and quality in a simulcast system. Does that mean that my hardware scanner all of a sudden supports simulcast and LSM-CQPSK? Or is it just good at cheating in that instance?

I am interested to know if DSD+ actually has separate demodulation support for LSM-CQPSK.

 

[AggieCon]

Ok. So what sdr trunk should I buy for my area of the northern wv panhandle? The digital systems are in Jefferson County Ohio and Ohio county wv both are p25 simulcast and trunked.

SDRTrunk is a specific software program. Try it first, because it is easier to install and use. There is TONS of information about software decoding and these software programs on this forum. Please do take a look. Voice/Control Channel Decoding Software - The RadioReference.com Forums

 

[Medziatkowicz35]

I meant the usb stick device sorry

 

[AggieCon]

What is your budget? No doubt, an Airspy is better than the RTL. I already offered my advice on the RTLs. They are plenty adequate to get the job done. It's hard to beat the $10 price tag. Just make sure whichever software you want to use supports the software defined radio you want to get.

I think I missed your post regarding your goal and limitations.

 

[natedawg1604]

There is no IF. DSDPlus 2.10 / 2.8 and maybe even 2.5 absolutely DO support LSM. I'm using DSDPlus 2.10 to monitor / voice follow a 9-site simulcast without any issues whatsoever, using FMP24/FMPA and DSDPlus.

All of my scanners / SDR stuff are connected to the same Stridsberg multicoupler and single antenna system. My PSR-500 / PRO-197 cannot even begin to decode the same system. My BCD436HP does a better job but anywhere good enough from my current location.

DSDPLus [at least when using FMPA and FMP24 to control the Airspy and RTL] is 100% decode, and it does a pretty damned good job even on weaker signals. I'm tickled pink by DSDPlus' performance.

I should also state that Denny's SDRTrunk also handles LSM and does a superb job monitoring the same system. Of course, I don't need to tell anyone that Max's OP25 does -- but it does

Mike

If DSD+ supported simulcast then I should be able to monitor my local simulcast system with no simulcast artifacts/distortion, right? As mentioned earlier, I am still hearing a materially significant amount of simulcast distortion with DSD+ 2.10, which is totally gone with OP-25. I am not accusing anyone of anything, I love DSD+ 2.10 and use it all the time for a lot of things. I am just telling you what I'm hearing with my own ears, and expressing my opinion that they haven't got simulcast quite cracked yet. I'm sure the DSD+ folks are very competent developers, I'm just expressing my personal opinion that they have a bit of work left to do re: simulcast support.

I will go ahead and make comparison audio files of OP-25 and DSD+ with my local simulcast system and post them here as soon as I can.

 

[Medziatkowicz35]

What is your budget? No doubt, an Airspy is better than the RTL. I already offered my advice on the RTLs. They are plenty adequate to get the job done. It's hard to beat the $10 price tag. Just make sure whichever software you want to use supports the software defined radio you want to get.

I think I missed your post regarding your goal and limitations.

My goal is to be able to receive Jefferson County Ohio and Ohio county wv from where I live in weirton,wv. Both systems are digital p25 simulcast and trunked. Also my limit is 50 to 60 to spend on a USB stick or other computer solution.

 

[Medziatkowicz35]

Ok I'm going to move to have this topic closed since there is No publicly available commercial scanner thst can handle lsm correctly. I have been told by radio reference police that discussion not relating to a scanner that can handle lsm properly , which we all know doesn't and probably won't ever exist, is not allowed in this thread.

 

[WQPW689]

Ok I'm going to move to have this topic closed since there is No publicly available commercial scanner thst can handle lsm correctly. I have been told by radio reference police that discussion not relating to a scanner that can handle lsm properly , which we all know doesn't and probably won't ever exist, is not allowed in this thread.

Become a moderator and knock yourself out.