2020 SDR Guide Ep 7 : Trunk DMR & NXDN digital with DSDPlus and 1 RTL-SDR

With a simple Software Defined Radio (SDR) and some free or frugal software, you can monitor digital radio systems like DMR and NXDN in your area.
This video is a demonstration of how I set up DSDPlus to monitor DMR and NXDN networks, and shows how to modify the various files that help the software trunk track the system with your SDR.
More details with links to the software (DSDPlus) and hardware (1 x RTL-SDR v3) I used in this video can be found at frugalradio.com/monitor-dmr
If you are unsure about how trunking systems work, I suggest watching the overview at the beginning of Episode 6 - • 2020 SDR Guide Ep 6 : ...
Other videos in my SDR beginner's guide can be found at • 2020 / 2021 SDR Guide
Timecodes :
00:00 - Overview of what you can hear
01:33 - How digital modes work
03:05 - DSDPlus & DSDPlus Fastlane
04:14 - Starting DSDPlus
08:34 - Using DSDPlus sites file
10:08 - Updating the DSDPlus frequencies file
12:26 - Updating the DSDPlus groups file (for talkgroups / TGs)
16:54 - Manually using RadioReference data to populate DSDPlus files
21:58 - NXDN (Nexedge) trunking demonstration / Lockouts & Priority talkgroups
24:01 - Thank you for supporting the Frugal Radio channel
Thanks for watching the Frugal Radio (FR) channel!

[@galacticboy2009]

Fascinating that some may call quotation marks, inverted commas. I hadn't heard that before. Great video!

[@wb7ond]

Great video, lots of great info on a complex software package.

[@FrugalRadio]

Thanks. There is a lot of software out there that can breathe a lot of life into these SDRs.

[@chrispowell3664]

Very informative video. I am just now using DSDPlus Eastland have a lot to learn still. Thanks for sharing your knowledge.

[@FrugalRadio]

You're welcome. Hopefully seeing it in action helps!

[@danedewaard8215]

Very Interesting!!! I definitely have to watch this video again, and then maybe again. Thanks!!!!

[@FrugalRadio]

Ha ha. Yes, DSDPlus isn't immediately intuitive but the results are worth putting the time in for. Good luck!

[@WXFD-Media]

I've been using DSD+ for over 8 years and never ventured into editing the files. Thanks so much for this tutorial! WX9SAR

[@FrugalRadio]

You're most welcome Terry. Modifying these files will really enhance your listening experience!

[@davidbee3704]

Fantastic. You make great content. Huge fan from Australia 👍

[@FrugalRadio]

Thank you David. I appreciate your comments. A lot of time goes in to the videos!

[@davidbee3704]

@@FrugalRadio i bet there's allot of work. We thank you and appreciate your efforts in sharing your knowledge. 🙏

[@yankeesierra8026]

a little correction if you dont mind 😁, there are only 2 (two) timeslots on DMR protocols, you were mentioning timeslot 4, timeslot 3 etc; but they are actually channel number (LCN). but thanks anyway for such clear and guiding video about SDR, i really enjoy the videos 😁😊 cheers mate 👍

[@FrugalRadio]

Ah, yes, I must have used the word timeslot instead of LCN. Thanks for pointing that out, I appreciate the correction :-)

[@K1ZEK]

GREATstuff.Hope to get active soon.

[@FrugalRadio]

Thanks. I hope you get active soon too. A lot of enjoyment to be had!

[@MrKillingsniper]

Nice video. Thank you.

[@FrugalRadio]

Glad you liked it!

[@humaxf1]

Excellent, straight to the point video as always. I signed upto the $25 fast lane program and is well worth it. I flick between sdr# and fmp tuner and both serve well. The display can be a bit confusing in fmp when the cursor is on your freq of interest and then a peak appears in the centre when the frequency is active - any ideas on the background to this?

[@FrugalRadio]

Yes, the DSDPlus window can be strange. I get a few signal apparitions as well, leading me to click on signals that aren't there! I don't know the background to why it does that with the window in the middle and the selected frequency being offset, but it works, so that's good enough for me!

[@pekwalker]

I've watched these first 7 episodes and am thinking the whole time, I wish you would do a step by step tutorial on one of these modes. For a beginner, you kind of just blow through it and its all very overwhelming. Interesting, but overwhelming.

[@FrugalRadio]

Thanks for your comments Peter. This is the reason I tend not to call the episodes tutorials. I hope people can still glean useful information from them though. Perhaps I'll branch out into tutorials in the future!

[@canuckchris5733]

I have just started my learning curve this month of sdr radio I will purchase a rtl v3 use cubic on Mac OS and plan on exploring trunk systems in Kelowna I am in an apartment facing another building 300 feet away I have a small balcony and wondering if a ml30 would be a good choice. Your channel has been awesome and have watched your 2020 guide. 🙏

[@FrugalRadio]

Nice to hear from you Christopher. The RTL-SDR v3 is a great VHF/UHF receiver and will serve you well in those bands, but the MLA-30 is an HF antenna. While the RTL-SDR will receive HF in Direct Sampling mode, something like an RSP1A would work better on HF. Or you could also use an upconverter (like the HAM it Up) for better reception. For VHF/UHF reception, I would start with the small dipole kit you can get with the RTL-SDR. With that, you'd be able to monitor local services more effectively.

[@acestudioscouk-Ace-G0ACE]

A lot of good stuff here! I might have to watch a couple of times to absorb it all. Are you able to use this software for amateur radio DMR? Perhaps you will be covering digital amateur radio applications in another video?

[@FrugalRadio]

There will be some future videos that look more closely at Amateur Radio, yes. And for sure, this software will allow you to monitor HAM band DMR repeaters, hotspots and simplex transmissions.

[@acestudioscouk-Ace-G0ACE]

@@FrugalRadio Thanks for the reply, I look forward to seeing those videos. I know how much effort it takes to make a good, educational video and appreciate your hard work.

[@FrugalRadio]

Thanks my friend!

[@Climb1Maintain]

Hi sir, thanks for the very clear explanation! I would like to ask if it is possible to decode the scramble of NXDN96 signal?

[@FrugalRadio]

I am unaware of any way to decode encrypted signals. In most countries, this would also be classified as an illegal activity.

[@prototype3a]

I need to give this a go as a nearby county uses NXDN. Your video "tutorial" should make getting it going easier.

[@FrugalRadio]

Good. NXDN 48 & 96 both decode well. Have fun!

[@prototype3a]

@@FrugalRadio If I'm honest, I'm really disappointed that DSDplus free version appears to be 5 years old and I have to assume that they have no intention of releasing an update for the free version. Two years ago, they said on their website that they would update the free version every six months.... IMHO, the "fast lane" is the current version and the free version is appears to be obsolete. At the moment, I can't even get FMPA to recognize my Airspy.

[@FrugalRadio]

They actually did a couple of updates to the free version files a while ago - I don't remember which ones exactly, since I use Fastlane. But I actually used the free version for years before I ever subscribed. I used it to monitor ProVoice, DMR & NXDN, along with P25 phase 2 IIRC, when no scanners on the market were available to do that. So despite being old, it is still capable of a lot!

[@prototype3a]

@@FrugalRadio If you say so. I tried it on my laptop and it seems to recognize my Airspy but I honestly have no idea if the software is even working properly. I'd love to try the current version to see if it works better but at this point there is no way I would give the developers a dime for this absolute mess of a piece of software.

[@FrugalRadio]

It's worth perservering with. There's definitely a learning curve with it though! That said, if you don't need to trunk track a network, there are simpler ways to demodulate the audio. Quickest for NXDN is probably to use a virtual cable from SDR#. Then instruct DSD free version to listen to that input. You don't have to use the FMP program that way.

[@pdxh0b0shack89]

seems there is no FMP24 related files in the current download, are you using fastlane?

[@FrugalRadio]

Yes, video was demonstrating Fastlane. I think you can can get one of the FMPs for the public release now, but I'm not 100% sure on that!

[@jeffchapman605]

Where is this documentation you referred to? P.S. I got a second SDR (Nooelec Smartee). Have that and an ETL-SDR running on a trunked system. Pretty good but still some simulcast distortion so I ordered a cheapy yagi to try to isolate down to a single site. Thanks again for your vids!

[@FrugalRadio]

Was I referring to the DSD Plus documentation? If I was, it can be found in your DSD installation folder. Check out some of the TXT files. They contain the documentation. Surprised to hear you're still getting the simulcast distortion with it. The Yagi solution may work quite well. Let us know how it turns out!

[@jeffchapman605]

@@FrugalRadio Yeah, I assume it's simulcast distortion anyway. I do seem to be getting a lot of errors intermittingly mostly on the CC. may not sound it, but I'm having fun tinkering. Cheers

[@FrugalRadio]

One thing you could try is adjusting your gain value. Sometimes that can make a big difference.

[@procast]

Hi, I am wondering how do you get the other frequency information when you only have the control frequency for that following site? Do you manually go into each voice transmission and note down their frequencies?

[@FrugalRadio]

The first thing is to check out radioreference.com if you're in North America. See if someone else has published the system info. Next step is to check National databases. TAFL here in Canada, FCC in the US. When looking up the control channel frequency you should find the account number or licence number. Then run a search with that, and you'll get a list of all the other frequencies they have available to them. The rest of the cover channels will be part of that list. Another way is to set up another SDR or even hardware scanner, and lol for where the signal appears each time an LCN is used. Sometimes they are close in frequency and easy to find. Other times there can be a larger gap. Eg control channel 461.775 , voice channels could be 461.825 and 453.675.

[@procast]

@@FrugalRadio Thank you for the guide but I'm all out of luck when it comes to RadioReference where I'm from. I was tracking a particular control channel but the thing is, there are a lot of other control channels near it so there is a ton of Cap+ activity in that band. This is because we have a single provider of DMR networks providing for multiple commercial companies that DMR pretty much has coverage like phone networks here. I do have another SDR due to me upgrading, maybe I'll have to figure out how to use two SDR to properly track trunking signals.

[@reedreamer9518]

Your video assumes I know all about the DMR trunk systems etc. But I've been a ham for years and not even the Extra class manual mentioned anything about DMR. Where do I learn all the fundamentals of DMR from the beginning up to what you are talking about in this video?

[@FrassoFra]

Hi! I'm having headache tring to learn how to TrunkTrak the only one site near me with a trunking system. This video is always my hope. What is the "rest channel"? This system is a Cap+ with multiple frequencies. And why the "1R current radios" doesn't appear to me when i start up the 1R bat?

[@FrugalRadio]

Cap+ systems don't broadcast a constant control channel, but the rest channel keeps track of what is going on through the system. If you modify your text files with the Cap+ LCNs you should be able to track it fine with DSDPlus. There's probably a menu option in the other window as well.

[@FrassoFra]

@@FrugalRadio well, i've set the LSN and Now i can Trak the system very easly! Thank you very much for your time! I've also found the "1r current radios". I'm Using DSDPlusUi, i found it much more intuitive

[@FrugalRadio]

Great to hear. I'm glad you persisted!

[@berndffm8420]

Thank you for your videos ! I can start fmp.exe, but I don't have a 1r.bat file. Where can I get it ?

[@OfficialChrisBreezy]

I appreciate for the videos. Now I can listen to my city fire & police department who using NXDN. Everybody else in the county using analog but still digital. I listen on baofeng uv 82 radio. Now I can use zello

[@OfficialChrisBreezy]

What the difference between NXDN 36 & 48? because my department just NXDN 😂

[@FrugalRadio]

NXDN 48 is a very narrow band signal. It is the only version supported by ICOM (at least their original radios anyway). Kenwood usually use NXDN 96, which is a wider signal (twice as wide as NXDN 48), but Kenwood radios can also be switched to NXDN 48 mode. To my ears they sound the same.

[@OfficialChrisBreezy]

@@FrugalRadio Ohhh, so if my department got kenwood radio it going to be NXDN 96?

[@FrugalRadio]

Kenwood can operate in either mode, so could be either, but most likely 96. The software decodes both though, so won't make a lot of difference to monitoring 😁

[@OfficialChrisBreezy]

@@FrugalRadio Can I do nxdn and p25 at the same time?

[@Aviator747a]

@Frugal Radio, Do you recommend DSD+ Fastlane over the free version? I finally got DMR to decode on ham DMR as well as a push to talk network "Bearcom". Unfortunately my local PD is P25 enc. sdr sharp is being finicky and freezing on me at times. I am contemplating on paying the $25 for life.

[@FrugalRadio]

I would say it is worth the money, for sure. However you can also give SDRTrunk a go as well. Evidently it does DMR now as well, although I haven't tried it myself.

[@Aviator747a]

@@FrugalRadio How often has fastlane been updating lately?

[@FrugalRadio]

I'm not 100% sure as I hadn't been down in the shack as frequently over winter!

[@xray9alpha]

@@Aviator747a fastlane has updated three times so far this year. Just updated yesterday (16 June) current release is DSD+ 2.324 and FMP24 2.74

[@HamTechRadioScannerDrones]

Hi how do i use an editor for windows 10 - Thanks

[@FrugalRadio]

Try downloading Notepad++

[@Aerococus]

Hello, congratulations on the excellent video and channel! I live in São Paulo, Brazil, and here are some DMR broadcasts. Unfortunately I am having a problem when I try to connect the DSD plus Fastlane with 20001. The following message appears: Initiating FMPx link using link ID 20001... FMPx link error = -5 [Server is not listening on selected link ID] How can I fix this problem?

[@FrugalRadio]

Hello Brazil, from Canada! Thanks for watching the channel - I'm glad you like the videos. There are lots of options for your receiver in DSDPlus Fast Lane. Make sure you are using the correct batch files when starting FMP. If you choose the wrong one, this is the type of message you get. Also you can check that your firewall is not blocking access to port 20001.

[@Aerococus]

@@FrugalRadio Thank you very much! Now it's working! Unfortunately most of the messages here are encrypted and I can't hear them. Congratulations on the excellent channel and videos!

[@FrugalRadio]

Great to hear it is working. But sad to hear about the encryption. Thanks for your comments 😃

[@chetnapatel9700]

Sir, can i use rtl sb used for tv which has FM etc ?

[@FrugalRadio]

Quite possibly. These SDRs started life as USB TV tuners, but not all can perform as wideband SDRs. It depends which computer chips are used inside it. You can go to zadig.akeo.ie and try the drivers there to see if it will work. If you replace your drivers, you would need to reinstall the original drivers to make it work as a TV / FM tuner again.

[@user-ml3jf7ef4c]

Is there a simple (or even automatic) way to find those freqs and identify wich mode it is (dmr, dstar, apco)? Radio reference has no info about my area.

[@FrugalRadio]

If you are in the US, then the FCC database would contain such information. Each mode of transmission has a code that identifies it. You can view a list of those codes at www.apcointl.org/spectrum-management/spectrum-management-resources/licensing/emission-designators/ When you view the FCC or Industry Canada databases, the frequency and emission code will be displayed, and you will then know what it is. The UK also publish transmitter site data, and probably many of the European countries. Just depends where you live I guess! Over time you'll get to learn the sound of many modes as you tune across the bands on your SDR or scanner. I know I can identify multiple types of digital signal as soon as I hear them. NXDN 48 sounds distinct from NXDN 96. DMR has its own sound, as does P25. Tetra looks and sounds different from the other modes as well.

[@user-ml3jf7ef4c]

No, i am from Moscow, Russia.

[@FrugalRadio]

Ok, the details will probably not be published there. A good site to check is www.sigidwiki.com/wiki/Signal_Identification_Guide Have a listen to some if the popular VHF & UHF modes there and hopefully you'll learn to tell what mode a signal is just by hearing it. Then you can use the right decoder to monitor it!

[@dronester7672]

I am hoping I am able to do something similar when I get my stuff in 2 days. It is not the typical rtl-sdr but NooElec NESDR Smart XTR Bundle - Premium RTL-SDR w/Extended Tuning Range. Will I be able to monitor and decode my local Barrie police with just one? They are showing it is DMR Motorola Connect Plus (TRBO) in the 142.xxx range. thanks I like all the videos.

[@FrugalRadio]

As long as your local PD are not encrypted, you should be able to decode them, yes. Enjoy your new gear when it arrives!

[@dronester7672]

@@FrugalRadio Will this require a second dongle or can I get away with just one? thanks for your help. I was hoping there might be a way using web-sdr to try and receive remote trunks?

[@FrugalRadio]

You'll only need the one dongle to get started decoding voice on the trunk when using DSDPlus. SDRTrunk can run with 1 dongle as well, but if the channels are outside 2MHz bandwidth, you'll miss some calls.

[@dronester7672]

@@FrugalRadio That is great! So with a single dongle I can use DSDPlus alone without other sdr software to act as the source? I checked and my local services are not encrypted just DMR/mototrbo

[@FrugalRadio]

Yes Robert, that is correct. DSDPlus will monitor the control channel and jump to follow voice traffic for any talkgroups based on the group priority. All with just 1 SDR. That is for the Fastlane version. I don't know if the free version also does that.

[@frankenberry9670]

A $25.00 SDR and how many dollars of antenna, cable and connectors? ;-) Very interesting, looks like I have another upcoming hobby. It would be nice if the various software designers made it easier to integrate with the reference web sites. Upload and download to import and export would be nice.

[@FrugalRadio]

Good afternoon! Connectors are a few bucks each, and RG6 cable is quite inexpensive (I pay around 30 cents per metre). The antennas can be home made very inexpensively - just a few dollars worth of parts. So for under $50 you could be well underway to enjoying the new hobby! Of course, like most hobbies, you can spend thousands if you want! Many of the softwares do offer import from the Radio Reference database which is helpful.

[@TwstedTV]

I tried the DSD+ I keep getting messages in the command-line window within Windows 10 telling me I don't have any audio, which is false, because I know I do. Its also telling me I don't have a RTL-SDR, which is also false, because its sitting right next to me connected to the antenna and computer. And ive been using it this morning to hear frequencies..... I haven't even started and this DSD+ and its already giving me headaches....LOL Also my folder does not have FMPA24, or the 1R bat file and I downloaded DSD+ from the official website. I dont know whats going on. 🤷‍♂ The zip I downloaded is called - DSDPlus1p101 zip I also downloaded the DSDPlusDLLs zip Next month or 60 days, ill be able to get the $25 lifetime version. Bills are coming in like hotcakes...lol

[@Rollmanrevolution]

ANYONE LOOKING TO DIVE INTO THE WORLD of SDR THIS VIDEO SERIES IS "TIP-TOP" ! To @FrugalRadio -- I am currently using 1 RTL-STR v4 with SDR# for basic monitoring -- and DSDPLUS Fastlane edition -- to run my Local County Truck systems --- is there any benefit to running 2 - Dongles over 1 ?? If you did a video on this I am sorry -- I have been trying to figure out If you would receive more or have more "Options" available using 2 dongles at a time? This so far has been a lot of fun - for under $100. The power of some of this software is INSANE in my opinion -- DSDPlus Fastlane is well worth the $25.

[@FrugalRadio]

No, I haven't done a video on DSDPlus with 2 SDRs. The primary benefit is that you don't miss any signalling on the control channel. So if you are logging all traffic, you would want 2. For casual monitoring of audio voice groups, 1 is sufficient.

[@MikeGriffiths1234]

I've been told that all our regional public safety transmissions (police, sheriff, fire, ambulance, highway patrol, FBI, etc.) are encrypted. Is that not the case most everywhere?

[@FrugalRadio]

No, it is very dependent on the region you are in. Some areas of the US have mandated that certain channels remain in the clear in order for public accountability. Other areas utilise encryption on almost all public safety transmissions. If you're in North America, have a look at the Radio Reference database for your State / Province. You'll soon see which agencies are encrypted and which are clear.

[@gotman4409]

I'd like to see more software for Linux Mint.

[@FrugalRadio]

I don't run much on Mint for the SDR, but I do have a Linux machine that is dedicated to decoding. The software it is running would also run on Mint. I expect I'll be using Linux when I do the weather satellite decoding videos.

[@jamesb8305]

I cannot find fmp24 files.

[@FrugalRadio]

They should be in the main DSD folder. If you're using the DSDPlus version. I'm not sure about the free version as I haven't used it in a long time.

[@jamesb8305]

Must be a free version thing.

[@radioxdeath]

I'm 4 blocks from a casino that uses some sort of Tier III system. 5 Freqs. Cannot for the life of me figure out the LCN. I use to work there and know it is indeed a trunked DMR system of some but for whatever reason my DSD+ won't give me any LSN/LCN data.

[@FrugalRadio]

Oh, tricky. I only have Connect Plus nd Capacity Plus systems within range of me. For those I used DSDPLus to work out the LCNs manually. I parked it on the control channel, then watched the FMP window for the upcoming transmission. When the control channel said a TG was using an LCN number, I was able to spot a new spike in the FMP window. That then gave me the frequency. The only problem was when the system spanned more than 2 MHz. For those ones I used 2 SDRs and a scanner to identify the LCNs.

[@radioxdeath]

@@FrugalRadio Weird. I'm seeing 0 spikes on FMP before a transmission. Wouldn't DSD+ Fastlane automatically see the leading or trailing data bits indicating where the rest channel is or is going?

[@FrugalRadio]

Yes, for a capacity plus system. TIII systems may not require a rest channel.

[@radioxdeath]

@@FrugalRadio Hmm I'm hearing audio on all the frequencies listed in the FCC Database and they are all licensed for trunking emissions. DSD is showing DMR only. No Cap+, Con+, TIII. I'm stuck. Lol I have no idea what I'm doing wrong.

[@FrugalRadio]

Are you using the free version of DSD, or the Fastlane version? You could also try SDRTrunk and see how it handles it?

[@ManuelPinner]

I have a SDR Play DX Receiver, for better than the SDR Sticks with SDR Angel and Soon SDR trunk,

[@FrugalRadio]

The SDRPlay receivers are very good. SDR Console works well with them too if you prefer not to use SDRUno. Will be nice when SDRTrunk can control them as well!