RTL-SDR P25 Decoding (Help)

[W5KYP]

Guys,
I have just received my first SDR dongle and was trying to tune in to the P25 Phase 1 system in my area.
I have watch the tutorial from this vidoe, https://www.youtube.com/watch?v=p4lrm_TxYuc and went through each step exactly how the guys says. Everything was installed and a reboot was done to complete installation.

Each time I start SDR# and use the VB cable to start decoding, SDR# locks up, I have to force it to shut down in task manager.

Is there something I'm missing?
Are there any other tutorials on how to accomplish this?

Thanks guys,
Pujo

 

[pinkfish457]

I don't know how far you got installing SDR#, but you may need to install the rtl--dll files. In the SDR# folder is a windows batch file: install-rtlsdr. Click on that and it will extract the files you need to run.

I also noticed this video shows only one frequency being used. This was not a control channel so it would not scan even if you had everything setup right.

I have a LWIN P25 system up and running here in Slidell, so I can guide you through the setup.

pinkfish457

 

[W5KYP]

That would be awesome.
At this time I only have 1 sdr receiver, I saw some are using 2 for scanning.
I prefer to do this on my MacBook however I can boot into windows if I can't do it in is x.

So, what do I need to accomplish this?

Thanks,
Pujo

 

[pinkfish457]

Okay, to begin, you need Unitrunker to decode LWIN. SDR# works, it's easier with Unitrunker. Check out Unitrunker, install it, and get back to me.

I have screen snips of the LWIN system here in Slidell I can send you.

 

[W5KYP]

I have both the applications installed....

Next?

 

[pinkfish457]

LWIN Setup

Okay, here are the Unitrunker LWIN setup files. This is using only one dongle. Two works better.

The first snip is the setup which you should already have. Input you own settings, for ppm, etc.
LWIN_VCO_S is the signal setup. Type in the working CC frequency on the PARK line.
LWIN_VCO_V is the voice setup. Set it up as I have and you should be good to go.

Make sure you set the sample rate in the first snip to .096 msps. If you set it higher is gonna bark.

You gonna need to find the working CC for Avoyelles parish from RR database, choose Avoyelles or Vick whichever is closest to you. Your also gonna need to download the working voice channels from RR also. Let me know if you haven't done this before.

Once you get that running you should see the channels pop up. Start DSD+ with the default settings, you can tweek them later.

I thing I have included everything you need to get started.

Good Luck!

 

[W5KYP]

if using 1 dongle, will it switch frequency's as needed ie trunked?
There are about 12 frequency's we use here in AP.
I can hear the CC and it is populating with all the channels and so forth however all I hear is either the control channel, or manually clicking the display when I see activity.

How will the setup differ if using 2 dongles, I have another on order.

 

[pinkfish457]

LWIN setup con't

After you have the CC up and running, on the Unitrunker, OPTIONS-RECEIVERS-SYSTEMS-ARCHIVE page, click on systems. See attachment. High lite LWIN as I have on mine, on the menu at the top click on the spoke wheel, download the system you want to run, eg Avoyelles parish. If it asks for a SID number it's 1113. That's the SID for Avoyelles. You need to download this for Unitrunker to populate. When you have this running and you can see activity, run DSD+.

Unitrunker will follow the channels it hears and ignore the rest.

You should not need to click on any channel as Unitrunker will do this for you.

PS: If the moderator wishes to move this to the Louisiana forum, I wouldn't have a problem with that.

THX

 

[W5KYP]

It's working!
Cool, thanks for getting me setup!

What do I need to do when I receive the second SDR receiver?

Again, thanks!

 

[pinkfish457]

First, you will need two antennas or a single antenna with a splitter. Setup the second SDR as you did the first. Change the line: ROLE to voice. Copy the information that you have in your 2nd VCO into this one, making sure you enter the correct ppm. AFTER entering the info into this SDR, delete the second VCO in your original dongle. It will not run otherwise. You should not need to download any further information as it will follow the voice channels as it did in your original setup.

Again, let me know if you need more info.

 

[CanesFan95]

What is an "LWIN" system?

 

[pinkfish457]

Louisiana Wide Interoperability Network

 

[W5KYP]

LWIN working in Avoyelles Parish

Thanks for all the assistance, it is working flawlessly!!

If I add a third RTL-SDR receiver, will that improve things or is there a limit to what can be improved?
I still see calls with a waveform on the O-Scope but no audio from time to time.

Will DSD+ decode Motorola? I am trying to listen in on the CLECO trunked system and I can see the control and it has discovered all the other frequencies, just wondering if DSD will do the job.


Thanks an have a great day!

 

[pinkfish457]

CLECO is an analog system. Unitrunker will do this as is. Setup the two dongles as before. You need to find the CC for you area. Enter it in the first dongle. In the second dongle PARK frequency you will need to enter a frequency that is close to the CC. Example, if the CC is 858.83570, enter as the PARK frequency 858.5000. Otherwise it will not run. As with LWIN you will need to find the SID for your area. Feed the analog audio in the 2nd dongle directly to your speakers. You will not use the digital output. Slidell has the same system. I and send screen snips if you need them.

I don't use three dongles, can't help you.

 

[W5KYP]

According to RadioReference, the control channel frequency is 939.73750. I put this in the first VCO and clicked play as to see if the CC will pickup the trunked frequencies. I am getting a list of only 2 other frequencies that are not listen on RR and are way off. The 2 frequencies are 857.32500 & 859.30000.
I am not sure but this doesnt look correct and I has set it up according to your previous post and I dont see anything happening, I can see calls but nothing else.

What do you think is going on?

-PuJo

 

[pinkfish457]

You need to use SDR# to check every CC to see which one is active. Some of the CC's listed in RR database are active and some are not. I saw there were two entries for Avoyelles parish. You may want to check the other site for an active frequency. The next time you run this system, it may be using another CC.