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

[AggieCon]

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.

Now this is some progress. You're going to be able to attain quality voice decode and monitor two systems simultaneously for 10% of the cost of a consumer hardware scanner.

With your budget, begin by buying two RTL SDRs (see the link I previously posted for cheap ones from Amazon http://www.amazon.com/Receiver-RTL2...le-Packages/dp/B015DN4DP6?tag=viglink20662-20). Approx $25 total for two. You can find them for $10 each, but the shipping takes much longer.

See how you can receive each system with the stock RTL or the antenna equipment you have on hand. If determined, you might need a tuned directional antenna for one of the systems. Antenna and adapters: $25.

You're going to start by using free software (SDR# and SDRTrunk). However, you will even have $10 left over to buy DSD+ if you want.

Once you get your RTLs in, feel free to post in the decoding forum (also previously linked) if you have any problems.

 

[radio3353]

Ok I'm going to move to have this topic closed since there is No publicly available commercial scanner thst can handle lsm correctly. .

This statement is incorrect. If you had been following the multiple LSM discussions of late you would know that some listeners do not have problems receiving a Phase II simulcast system using consumer gear. It is all about location in relation to the towers.

Although not classified as a scanner, there is commercial gear (Motorola, Unication, etc.) that receive simulcast systems just fine.

There is no reason to close a thread that discusses a legitimate technical topic.

 

[Medziatkowicz35]

Ok how much is the unication, Motorola, etc gear?

 

[bailly2]

if you already have a p25 scanner, paint can surrounding a stock antenna stops simulcast distortion better than a yagi

 

[AggieCon]

None of the consumer handhelds handle simulcast correctly. Just because some might do a decent job decoding in certain locations does not mean that they do simulcast correctly, have the proper hardware configuration, or support CQPSK demodulation.

Of course, there are commercial products that handle these systems; if not, these systems would be completely worthless. I figured these options were out of the price range for the OP. However, he might have success with the Unication G5 dual band UHF/700/800 pager. I don't know what these will sell for, but I assume it will be in the upper three figure range, perhaps even over $1,000. The drawback to this device would be that it is for "scanning" rather than "searching." You would have to know the specific frequencies and talkgroups you want to monitor (i.e. rely on a database that might not be complete or use your UniTrunker data to know what to program).

I can't find information regarding what modulation the Unication G4/G5s support or any statement that it supports simulcast. Does anyone have any official documentation regarding Unication and simulcast?

 

[Spitfire8520]

I can't find information regarding what modulation the Unication G4/G5s support or any statement that it supports simulcast. Does anyone have any official documentation regarding Unication and simulcast?

Unication USA

What systems does the G4 support?

• The G4 supports multiple P25 systems, including Conventional, P25 Trunking, and P25 Conventional.
• The G4 Supports:
  • Multiple IDs
  • Site Trunking
  • Full Spectrum Scan
  • Linear Simulcast Modulation for Simulcast Applications
  • Priority TGIDs
  • Multiselect
  • 800MHz, 20kHz channel spacing and 4kHz deviation for Direct mode Communications

 

[natedawg1604]

Okay, as promised here are links to download 3 audio files of my local simulcast system from 3 different programs (OP-25, DSD+ 2.10 and SDRTrunk). Please note, I ran CC & VC copies of DSD+ 2.10 with FMP24 in the standard TCP Link configuration.

I generated approx. 10 minutes of audio (single .wav file) with each program continuously scanning through the talkgroups. It appears OP-25 has the cleanest audio and the best simulcast decode, with SDRTrunk coming in second. And, IMO DSD+ comes in a distant third re: simulcast decode performance (at least for the specific simulcast system in my area).

As you can see, from approx. 3:00 -3:17 on the audio file for SDRTrunk, you can hear continuous simulcast artifacts for approx. 17 seconds. You can also hear this at approx. 5:04-5:06.

DSD+ is even worse. The entire audio clip is cluttered with simulcast distortion, jitter etc. which is virtually 100% absent in the OP-25 audio sample. If anyone has suggestions re: settings I can adjust on DSD+ to eliminate the simulcast distortion, please let me know.

First, this is my Simulcast System on OP-25.

Second, this is the same system on DSD+.

And finally, here is the same system on SDRTrunk.

 

[AggieCon]

Overall, SDRTrunk sounds slightly metallic. I agree, it decompensated a bit after 3 minutes.

I don't think this is a fair characterization of DSD+. Your audio file was way hot and clipped most of the time. That's the only distortion I noticed, not decoding problems. Granted, I didn't listen to it much since it was too painful.

Try to adjust the audio gain out of DSD+. In my version, it is the -g attribute.

 

[natedawg1604]

Damn you are right about the gain issue in the DSD+ file, I will re-run that again like you suggested...

 

[slicerwizard]

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

I'm just using a couple of mini magmount antennas on my vehicle. They're probably dual band ham antennas tuned for 140 and 440. They look somewhat similar to this, but longer: http://www.alibaba.com/product-detail/Factory-Price-Long-Range-4g-Lte_60408489183.html

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.

Ok, so it's not just me...

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.

Wut? Two of the CC logs show virtually zero symbol decoding errors. A voice channel with a perfect decoding rate will sound fine.

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

It obviously does.

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.

Given your desire to spend as little as possible, you might as well go with the cheapest dongles you can find, like the ones Aggie linked to. Just be aware that with them and the dinky antennas they come with, you're limited to 700+ MHz systems (unless you have VHF/UHF sites within a couple of miles) and the antennas will be located fairly close to your PC. If you need antenna(s) mounted outside to hear the sites of interest, well, there goes your budget, and you'll be needing some pigtails to convert from MCX to whatever is on the end of your outdoor antenna's coax - probably BNC.

Ok how much is the unication, Motorola, etc gear?

Well outside your budget.

If DSD+ supported simulcast then I should be able to monitor my local simulcast system with no simulcast artifacts/distortion, right?

You've stated that you get some artifacting from SDRTrunk. So now it doesn't support simulcast?

You say DSD+ doesn't support simulcast. I say it's come a long way. I'm not saying it's done. Fast Lane releases are essentially beta releases after all.

As mentioned earlier, I am still hearing a materially significant amount of simulcast distortion with DSD+ 2.10

Have you taken this up with the developers? If there's something about your RX situation that DSD+ isn't handling, provide them with whatever they need (I/Q samples, I would assume) and get it fixed.

Okay, as promised here are links to download 3 audio files of my local simulcast system from 3 different programs (OP-25, DSD+ 2.10 and SDRTrunk).

Where's the comparison with DSD+ 1.101? If 2.10 doesn't support simulcast, it should sound the same as 1.101, no?

 

[AggieCon]

Not all voice decoders are equal. Different programs and different decoders don't necessarily handle the exact same error-free data the same. Throw in data that is less than perfect, and there can be a big difference between various software/hardware applications.

For example, even OP25 has two different voice decoders. For me, one of them works better than the other.

What I am trying to establish is two pronged: 1) Does a solution specifically support LSM-CQPSK? 2) Regardless of official support of LSM-CQPSK, how does the solution work real world?

I know it might seem like semantics, but it's a legitimate differentiation. I don't doubt your DSD+ performance -- my experience is with the free solutions. Let's try to agree on some vocabulary: Whether something is supported or not depends on the actual hardware and software... and whether the solution works well or not for a specific scenario is not a commentary on whether or not a specific technology/modulation/system/etc. is supported by said solution. Does that make sense?

P.S. Those cheap RTLs and their cheap antennas can work just fine on 800mHz systems. Here's proof: http://forums.radioreference.com/2584454-post578.html

 

[natedawg1604]

Update: Well now I feel kinda stupid, it appears I was using wayy too high a gain setting with DSD+ for my simulcast system. Here is another audio recording of my local simulcast system on DSD+ 2.10 with a gain of -g5.

It appears the audio & decoding definitely improved by lowering the gain. However, it seems like you can still hear simulcast artifacts, because the audio still sounds a bit choppy. Maybe I still need to mess with the gain setting. Also, I re-installed DSD+ 1.101 and monitored this same simulcast system with Unitrunker - the decoding was horrific. So, quite obviously they did make great improvements re: simulcast in DSD+ 2.5.

IMO OP-25 still sounds better and decodes simulcast noticeably better. Indeed, putting simulcast decoding aside, I tend to think the audio in OP-25 sounds better overall (i.e. for all P-25 systems), it seems a bit cleaner with a somewhat better dynamic range.

re: SDRTrunk, I'm not sure why I was hearing what appeared to be *some* simulcast artifacts earlier today in that program, I haven't used it much and I know it's still in the fairly early development stages. I'll try and play with it more in the near future.

 

[slicerwizard]

What I am trying to establish is two pronged: 1) Does a solution specifically support LSM-CQPSK? 2) Regardless of official support of LSM-CQPSK, how does the solution work real world?

Well, I tried it on every simulcast system/zone around here. That's about 15 separate zones. It includes a couple of non-simulcast zones that are using CQPSK, no doubt to handle Phase II talkgroups.

I know it might seem like semantics, but it's a legitimate differentiation. I don't doubt your DSD+ performance -- my experience is with the free solutions. Let's try to agree on some vocabulary: Whether something is supported or not depends on the actual hardware and software... and whether the solution works well or not for a specific scenario is not a commentary on whether or not a specific technology/modulation/system/etc. is supported by said solution. Does that make sense?

The difference between 1.101 and 2.10 is night and day. How does that happen without specific support?

I just downloaded the 1.101 files and set them up in their own folder and ran 1.101 FMP/DSD+ against 2.10 FMP24/DSD+ on the same CQPSK voice channels using identical rtl-sdr.com dongles and antennas. To be fair, I tried swapping antennas and even the dongles themselves. I tried different filter bandwidths in FMP. I tried tweaking the gain level. The results were always the same - the 1.101 side had massive errors and kept losing sync; the 2.10 side decoded pretty much everything.

Here's a pic: Imgur: The most awesome images on the Internet

After both dongles were tuned to 862.2625, the only thing 1.101 added to its event log was a neighbour entry. 2.10 has five group calls, which is all of them, logged with correct source/target values and encryption data. The 1.101 console window has nothing useful - it's all errors. It stuttered along (slowly) while the 2.10 console window scrolled normally.

P.S. Those cheap RTLs and their cheap antennas can work just fine on 800mHz systems.

Which is why I wrote 700+ MHz.

 

[mtindor]

Update: Well now I feel kinda stupid, it appears I was using wayy too high a gain setting with DSD+ for my simulcast system. Here is another audio recording of my local simulcast system on DSD+ 2.10 with a gain of -g5.

It appears the audio & decoding definitely improved by lowering the gain. However, it seems like you can still hear simulcast artifacts, because the audio still sounds a bit choppy. Maybe I still need to mess with the gain setting. Also, I re-installed DSD+ 1.101 and monitored this same simulcast system with Unitrunker - the decoding was horrific. So, quite obviously they did make great improvements re: simulcast in DSD+ 2.5.

IMO OP-25 still sounds better and decodes simulcast noticeably better. Indeed, putting simulcast decoding aside, I tend to think the audio in OP-25 sounds better overall (i.e. for all P-25 systems), it seems a bit cleaner with a somewhat better dynamic range.

re: SDRTrunk, I'm not sure why I was hearing what appeared to be *some* simulcast artifacts earlier today in that program, I haven't used it much and I know it's still in the fairly early development stages. I'll try and play with it more in the near future.

I don't know if DSDPlus recommends this, but I specifically run -f1 -mp (force Phase 1, use PSK optimization). If you use -mp, don't try to decode a non-simulcast P25 Phase 1 system though because you won't be able to [and dsdplus -h tells you so].

I just disabled -mp on mine, and I can't tell if there is much of a difference or not. But I'd try "-f1 -mp" specifically for P25 Phase 1 simulcast systems and see if improves any more than it already has for you.

I would suggest that you use "b" in your FMP to toggle between the bandwidths, but I think if you lock in -f1 -mp (or if LSM is detected automatically), you can't adjust bandwidth anyway because I believe the whole package specifically fine tunes everything when a simulcast sig is detected. Could be wrong.

-f1 -mp is worth a try though. It may not do anything as -mp may already be in use once simulcast is detected.

Mike

 

[Medziatkowicz35]

I'm just using a couple of mini magmount antennas on my vehicle. They're probably dual band ham antennas tuned for 140 and 440. They look somewhat similar to this, but longer: http://www.alibaba.com/product-detail/Factory-Price-Long-Range-4g-Lte_60408489183.html



Ok, so it's not just me...



Wut? Two of the CC logs show virtually zero symbol decoding errors. A voice channel with a perfect decoding rate will sound fine.



It obviously does.



Given your desire to spend as little as possible, you might as well go with the cheapest dongles you can find, like the ones Aggie linked to. Just be aware that with them and the dinky antennas they come with, you're limited to 700+ MHz systems (unless you have VHF/UHF sites within a couple of miles) and the antennas will be located fairly close to your PC. If you need antenna(s) mounted outside to hear the sites of interest, well, there goes your budget, and you'll be needing some pigtails to convert from MCX to whatever is on the end of your outdoor antenna's coax - probably BNC.



Well outside your budget.



You've stated that you get some artifacting from SDRTrunk. So now it doesn't support simulcast?

You say DSD+ doesn't support simulcast. I say it's come a long way. I'm not saying it's done. Fast Lane releases are essentially beta releases after all.


Have you taken this up with the developers? If there's something about your RX situation that DSD+ isn't handling, provide them with whatever they need (I/Q samples, I would assume) and get it fixed.



Where's the comparison with DSD+ 1.101? If 2.10 doesn't support simulcast, it should sound the same as 1.101, no?

I have an outdoor antenna now but it is a bns wireless ya70014f. That won't do 800 or 400 MHz will it? I know radio shack sells antenna that do 800mhz for $60.

 

[AggieCon]

Well, FWIW, my cheap RTLs also decode conventional VHF digital frequencies. I know there are better receivers, but, when you consider price, these little things are hard to beat.

I think the modulation used by simulcast systems is slightly different than the H-DQPSk used for TDMA downlink. However, if they bought phase two capable equipment with linear amplifiers, I suppose that might be reason to use CQPSK instead of C4FM.

Thanks for the info regarding DSD+ improvements. I can't wait to try it out.

 

[Medziatkowicz35]

I want to find a usb stick that decodes scanner frequencies. I know I was given some but unfortunately they will be 10 to 14 days for delivery. I was hoping to have one for under $20 and have it by Saturday or Monday.
Will my ya70014f antenna receive 800mhz and 400 MHz signals?

 

[AggieCon]

I want to find a usb stick that decodes scanner frequencies. I know I was given some but unfortunately they will be 10 to 14 days for delivery. I was hoping to have one for under $20 and have it by Saturday or Monday.
Will my ya70014f antenna receive 800mhz and 400 MHz signals?

Then find one of the ones that has Amazon Prime and pay for faster shipping. You're going to need to double your RTL budget for the same product, however. See PM re antenna.

 

[Medziatkowicz35]

double my rtl?

 

[mtindor]

I want to find a usb stick that decodes scanner frequencies. I know I was given some but unfortunately they will be 10 to 14 days for delivery. I was hoping to have one for under $20 and have it by Saturday or Monday.
Will my ya70014f antenna receive 800mhz and 400 MHz signals?

Your ya70014f will be fine for 700/800 mhz monitoring of the MARCS-IP stuff across the river in Jefferson.

Your ya70014f will be much more limited on 400 mhz since its sweet spot is on 700/800. But, it should not prevent you from obtaining a very strong signal on SIRN Weirton (when it is up) and SIRN Ohio Co Simulcast.

Now, if you want to listen to 400/800 stuff outside of SIRN Hancock-Brooke-Ohio and MARCS-IP Jefferson Co, you will probably need a different antenna for 400 mhz stuff more than a county away.

Mike