Tag Archives: Trunked Radio System

One of the responsibilities of the Technical Coordinator in the Ohio Section is to submit something for the Section Journal. The Section Journal covers Amateur Radio related things happening in and around the ARRL Ohio Section. It is published by the Section Manager Scott – N8SY and articles are submitted by cabinet members.

Once my article is published in the Journal, I will also make it available on my site with a link to the published edition.

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Now without further ado…

Read the full edition at: http://n8sy2.blogspot.com/2016/08/august-edition-of-ohio-section-journal.html

THE TECHNICAL COORDINATOR
Jeff Kopcak – TC
k8jtk@arrl.net

Hey Gang,

As I’m beginning this month’s article some nasty storms just ripped through Cleveland on the 11th. There were branches, trees, wires, power lines down, and road closures on the west side due to those hazards, including my QTH of Westlake. Luckily I’ve heard of no injuries. If you’re not part of the NWS Skywarn program, please consider joining as a spotter. Skywarn is a volunteer program that helps the local National Weather Service office know what’s happening on the ground and assists in warning people about dangerous weather conditions. Training typically happens in the early spring for spotters. Check with your local club or Skywarn organization.

The Republican Nation Convention went off without major incident in Cleveland. I was working from home and had the scanner on most of that week. Three major trunked radio systems were utilized: MARCS, the new MARCS-IP (Multi-Agency Radio Communications System), and GCRCN (Greater Cleveland Radio Communications Network). If you didn’t set a wildcard or use UniTrunker to watch those systems, you probably missed a lot of the event communications. There were about 12 primary talk groups on GCRCN where most of the action took place. These were previously unidentified so they were not in any lists or databases that use Radio Reference. A wildcard stops on any talk group whereas programming specific talk groups into the scanner will only stop on transmissions for those talk groups. The “old” MARCS system was shut down immediately following the convention as it was kept online largely for backup. It has been replaced by the MARCS-IP system.

This month we learned the sad news of Hara Arena’s closing. No more Hamvention at Hara Arena after 52 years. The Dayton Amateur Radio Association put into action their contingency plans. It was announced that Hamvention will still be in the Dayton area. The new location is The Greene County Fair and Expo Center located in Xenia, Ohio. Michael Kalter and Ron Cramer talked about the new location on Ham Nation for about 30 minutes in episode 259. Couple of links worth visiting:

-Why we are saddened by the loss of the Hara Arena: http://ad8bc.com/bc/?p=601
-Hamvention Announces Venue for 2017: http://hamvention.org/hamvention-announces-venue-for-2017/
-Ham Nation episode 259: https://twit.tv/shows/ham-nation/episodes/259, or YouTube link: https://www.youtube.com/watch?v=g_OaKmllEDY

One of our Technical Specialists, David KD8TWG, has been involved with setting up a DMR repeater in Cleveland. The frequency is 442.0875 (+5 MHz standard offset) using Color Code 1. The repeater is connected to the K4USD cBridge (http://www.k4usd.org/). On that website is a listing of the “standard configuration” for repeaters connected to the bridge. Right now, your code plug should follow the layout listed on the site. A cBridge is a feature that allows interconnecting of repeaters over the Internet and a Color Code is equivalent to a PL tone or DCS on analog repeaters.

When I picked up my DMR radio at Dayton, I found a code plug that had repeaters in Dayton and Columbus for the drive home. It was a nice opportunity to quickly get on the air with DMR but I kept threating myself to write my own. With the installation of the repeater in Cleveland, I took the opportunity to do just that. What is a “code plug?” Some history I found online notes the origins came from wire plugs, later jumpers, which were plugged into the radio to enable certain options or features. Since everything is now processor based, the term continues to stick with the radio world and is a fancy word for ‘radio configuration.’ It contains transmit/receive frequencies, tone selections, timeout values, IDs, configuration settings, etc. I used the one I found in Dayton as a reference. There is also a sample one on K4USD’s site for my radio. I compared the two and designed mine the way I thought worked best. Just because someone designed a code plug one way doesn’t mean you can’t modify or do it differently. It’s analogous to one ham’s memory channels are not the same as another. In the end, it took about 3 hours to make mine! Keep in mind that was a lot of learning and comparing, in addition I programmed all 65 possible talk groups so I don’t have to add them in later. From discussions on the air indications are it took others a few hours as well. But my code plug works! I couldn’t be happier. Well OK I could, apparently I’m just far enough away that my 5 watts doesn’t quite make the trip. I took the radio to work and tested it from there.

I am writing an introductory series for the Wood County Amateur Radio Club on getting started in digital modes. The first few articles were for those who have never worked digital and want to upgrade their station. Remaining articles will focus on a specific mode. I’ve completed 3 so far (starting in February): an introduction, station setup, and working JT65/9. Published versions can be found at the club’s website in the CQ Chatter newsletter: http://wcarc.bgsu.edu/. As I point out in the second article, Technician class licensees can still participate. All of these sound card digital modes can be operated over FM simplex or even a net on a repeater using an HT! There are clear downsides like not being able to transmit as far as an HF station and occupying the full 10 to 15 kHz FM, even though the bandwidth of the audio generated by the computer is less. Yes, this defeats the purpose of narrow bandwidth modes. Someone wanting to learn and experiment with these modes may get bitten by the bug and lead to a license upgrade. That’s how I did it. I plan to write an article every 2-3 months.

My dad and I had the opportunity to join the Toledo Mobile Radio Association (TMRA) on August 10. They had Chris Wilson N0CSW, National Sales Manager for Yaesu talk about their System Fusion. Chris did make it clear that the company was paying for travel so there would be some ‘sales pitches.’ The presentation was short but the program ended up being driven by the audience with a lengthy question and answer session. Some things I learned: the DR-2X repeater announced at Dayton is not going to be a replacement for the DR-1X, though they may have improved on some shortcomings. The 2X is more of a full featured repeater. It will have the ability to operate dual receive and dual transmit (but not at the same time) creating two repeaters from one unit. They are including voice messaging (like club meeting announcements). Mailboxes were users can record messages for others. This reminds me of the mailboxes repeaters used to have when autopatches were more prevalent. The 2X can monitor a separate control channel for commands. This repeater will not support WiresX but will have “MSRL” (Multi-Site Repeater Linking) via an add-on Ethernet port. Their linking technology will allow the repeater to be linked over any IP based network, including mesh. This brought to mind an interesting use-case where multiple low profile/portable repeaters could be linked at sites with mesh such as air ports, hospitals, and Red Cross shelters. This would create a linked repeater system where not as many users would have to setup cross-banding or run to the other end of a hospital to reach a radio. In contrast, something similar can be done using the AllStar Linking system. At the meeting there was alot of: “I would like this feature/I don’t like this feature in the radio,” “we’re having this problem setting up the repeater to do X” kind of Q&A. My take away from that, their plan is to add features to radios by firmware update and not always release new radios.

In addition to all the work David KD8TWG has been doing to get DMR up and running in Cleveland, he’s been helping repair and upgrade analog repeaters, and setting up APRS IGates around town. He will be giving a presentation on APRS at the Lake Erie Amateur Radio Association’s club meeting on August 30th. Dinner starts at 6:30pm with the meeting at 7:30, don’t need to have dinner to attend the presentation. Haven’t seen an official announcement on location yet but it’s expected to be at the Play Arcade in Mayfield Hts (5900 Mayfield Rd, Mayfield Heights, OH). Check the LEARA website for updates and for dinner reservations: http://www.leara.org/.

I will be giving my introductory Raspberry Pi presentation at the Cuyahoga Amateur Radio Society meeting, September 13 at 7:30pm. It will be updated as there is new hardware and innovations available. Their meeting location is the Busch Funeral Home, 7501 Ridge Rd, Parma, Ohio. More: http://www.2cars.org/.

Thanks for reading and 73… de Jeff – K8JTK

Amateur Radio, ARRL Ohio Section, Ohio Section Journal

Ohio Section Journal – The Technical Coordinator – July 2016 edition

July 14, 2016 Jeffrey Kopcak

Once my article is published in the Journal, I will also make it available on my site with a link to the published edition.

Now without further ado…

Read the full edition at: http://n8sy2.blogspot.com/2016/07/july-issue-of-ohio-section-journal.html

THE TECHNICAL COORDINATOR
Jeff Kopcak – TC
k8jtk@arrl.net

Hey Gang,
It’s been a busy month with ham radio holidays and national holidays. June was a great operating month for me as I had taken some time off work after Dayton. Since I really hadn’t been on the air the first half of the year, I spent a lot of time catching up. Heck April I made a total of three contacts. Bleh. I racked up 130 contacts including Field Day and 17 National Park activations. As usual I’m coming to the party late on NPOTA so I’m getting there. Our own Affiliated Clubs Coordinator John KD8MQ has given many updates in past editions of the Journal; check them out. More: https://npota.arrl.org/

I will tell you no matter what you do for Field Day, you’re always going to have a good time. If you get together with a club or some buddies, there are going to be good stories too. This year I took a different approach and decided to operate as a 1D station. Still had a good time. It gave me a chance to refresh my memory and practice using the Digital Signal Processing (DSP) and filtering features of my radio. As one would expect, there were stations all over the place. The bands weren’t that great either. I would hear a station but not clearly. I used different Automatic Gain Control (AGC) settings, Noise Reduction, filters, Passband Tuning (PBT), the whole nine yards. If I wasn’t hearing much scanning around, I would go work on something else and come back later to work more stations. In total made 30 contacts mostly on 40m from the home QTH.

The following weekend was Canada Day and the Independence Day holiday weekend. First up was the Radio Amateurs of Canada (RAC) Canada Day contest on July 1st. Since I’m a station outside Canada, the exchange was RST and serial number. The serial number was the number of Canadian stations worked during the contest. I worked 14 stations total over the 24 hour contest.

Then (of course) starting Friday morning was the 13 Colonies Special Event. There is one station in each of the 13 original colonies and two bonus stations. Bonus stations are Philadelphia where independence was declared and England for the “British Standard” contact. Things were going well for me. I started out working 9 stations on Friday night and 5 on Saturday morning. Then nothing. The British bonus station was eluding me. I kept trying when they were calling on sideband but they never came back to me or by the time they went through the numbers and got to 8 – they were down in the noise. It wasn’t looking good. In literally the 11th hour, I finally made contact with England on PSK for my clean sweep! I’ll be sending away for my certificate and sending out QSL cards soon. If you worked any of the 13 colony stations, please support them by making a donation or sending in for a certificate. Many stations took time out of their holiday weekend to put on another successful event. More: http://www.13colonies.info/

Last month I mentioned the Portage County Amateur Radio Service was going to have an Earth-moon-earth presentation for their July meeting. I’ve never experienced or knew anyone that worked EME so this was a presentation I did not want to miss. It was a bit of a drive in rush-hour traffic from downtown Cleveland. Nonetheless, food was great and it was an excellent presentation. Tony WA8RJF talked about the properties and theories involved making EME contacts, early days of EME needing monster arrays with gain antennas and rotor controls the size of two truck-beds –in one case. Then he talked about JT65 being the game changer to make EME communication more accessible to regular hams. The majority of my HF contacts are JT65 so a lot of it hit home for me. JT65 was originally created for EME but later adapted to HF and has become the second most popular digital mode. Thanks to Tony and PCARS for allowing me to be a guest at their meeting.

Speaking of modes I haven’t yet operated, the QSO Today podcast interviewed Art Towslee WA8RMC of Westerville who is heavily involved with ATV (Amateur Television, sometimes called Fast Scan TV). ATV uses video and audio much like a commercial broadcast station. In many ways you are operating from your own studio with a video camera, microphone, lights, or other video sources. In the podcast they about Art’s history, knowledge, and involvement in projects to move ATV forward using Digital TV standards. With the introduction of Digital TV, quadcopters and 4K resolution, ATV is becoming popular once again. Slow Scan TV in contrast is sending a single still image over the air. More: http://www.qsotoday.com/podcasts/wa8rmc and https://atco.tv/

The TAPR Digital Communications Conference is coming up September 16-18 in St. Petersburg, FL. The list of speakers and forums haven’t yet been released but topics will likely include Software Defined Radios, digital voice modes (D-STAR, Fusion, DMR, P25, Codec2, FreeDV), digital satellite communications, APRS, and the like. More: https://www.tapr.org/dcc.html

In a great article from ARS Technica, they talk about the Linksys WRT54GL router that is 11 years old and still making millions for Linksys. This router came out in 2005 but really had an ecosystem built around it. The router was Open Sourced making it easily modifiable and turning it into a much more powerful router. We hams have seen this first hand as these are one of the more popular models used in Mesh Networking. Linksys said they’ll continue to make the router while suppliers keep selling the parts; great news for Mesh users. More: http://arstechnica.com/information-technology/2016/07/the-wrt54gl-a-54mbps-router-from-2005-still-makes-millions-for-linksys/

On a sad note that hits close home, especially those in Cleveland. At the end of July, Amateur Radio equipment retailer Amateur Electronic Supply (AES) will be closing for good. We all have stories about the long time retailer. I liked browsing the show room and playing with the radios on display. They were always helpful to their customers. It’s sad to see a retailer leave and friends lose their job. 73’s to the AES crew. You will be missed. More: http://www.arrl.org/news/amateur-electronic-supply-closing-after-59-years-in-business

That’s about it for this month. With the conventions going on in the state, everyone please stay safe. As I’m writing this a few days before the RNC, there are plenty of changes happening in Downtown Cleveland: unmarked SUVs, helicopters flying around, “Cell on Wheels” (COW, portable cell sites) popping up, temporary stages going up, and TV equipment trucks. My company has made previsions for us to work remotely. Those with a P25 digital trunked capable scanner in the Cleveland area will probably find most activity on the Ohio MARCS-IP (Multi-Agency Radio Communications) and GCRCN (Greater Cleveland Radio Communications Network) systems. The old MARCS 3.5 legacy system is going to be kept on-line as a backup to the MARCS-IP system. After the convention that system is expected to be fully shutdown. No definitive word on talk-groups to listen to but keep an eye to the Radio Reference Ohio forum and frequency database pages as things gear up.

Thanks for reading and 73… de Jeff – K8JTK

Computing, Tutorials

P25 Trunked Tracking and Decoding with RTL-SDR, Unitrunker, and DSDPlus

December 12, 2014 Jeffrey Kopcak

The project that got me really into experimenting with the RTL-SDR dongles is using them to decode P25 digital trunked public service radio systems. I have been a casual scanner listener for years and like to listen to emergency calls nearby. In college it was great to listen in on a party weekend hearing fights, disturbances, or why my street suddenly filled with cars at 3 AM.

Narrowbanding

That was when most agencies were analog. To get more use out of the radio spectrum, the FCC decreed a narrowbanding mandate requiring a “maximum of 12.5 kHz bandwidth across the private land mobile bands between 150-174 and 421-512 MHz.” This means going digital for much of that radio spectrum because traditional FM transmissions are 15 KHz. Ironically they will “go digital” but move to 700/800 MHz.

As a casual listener, I wasn’t exactly thrilled with spending at least $500 for a scanner capable of digital (P25 mostly) and trunked system tracking (also Radio Reference wiki).

$40 RTL-SDR trunked scanner

Lurking around the Radio Reference forums, I saw references to being able to use the RTL-SDR dongles for trunked digital decoding. I had to try it. I had played around with these dongles and read about the many projects people were doing with them. In actuality this project cost me $65.

About the project

You will need at least two RTL-SDR dongles ($20/each) and a copy of Virtual Audio Cable ($26). I already had a premium Radio Reference account. You can do the project with one dongle but you loose many features in Unitrunker like talkgroup priority. Theoretically, the single dongle listens to the system control channel and then tunes to voice calls, then back to the control channel. You will miss calls because that notification comes across the control channel while the dongle was tuned to a voice transmission. I will cover a two dongle setup and do not plan to cover a single dongle setup.

This project is still very complicated but it is MUCH easier than it used to be. This manly thanks to Rick, the developer of Unitrunker who implemented support for the RTL-SDR chipset in his program. Previously, there needed to be a plug-in for both Unitrunker and SDRSharp, there were all kinds of “moving parts.” In one respect, being able to see the signal waveform on a spectrum analyzer made it much easier to fine tune the PPM correction on-the-fly as opposed to guessing on a modulation scope. This setup is much cleaner and the Unitrunker developer has implemented advanced features like drift correction. It will take some time and patience to understand, research, and know the types of systems and system specifics.

There are some advantages like cost and being software based. Changing modulation types is often as easy as changing programs. As an example, DSDPlus will decode MotoTrbo as opposed to no standalone scanner being able to do so currently. However, portability of this setup is limited as you have to have many pieces of equipment with you. You’ll need an Internet connection to find sites to program and a PC to tweak settings.

Two very specific and key things to note about trunked radio systems in general:

You cannot tell the tower your’re listening to which talkgroup you want to monitor. Doing so would require the ability to transmit and IS ILLEGAL because you are not authorized to do so. If the talkgroup is not transmitted by the tower, you’re out of luck. You can’t be in Dayton and tell the system you want to listen to a talkgroup originating from Cleveland.
Nothing here (and no program I know of) will defeat encryption, even if you own the keys. Decoding encrypted transmissions is not implemented in any of these programs. On the flip side, be aware that using this tutorial and feeding the audio to Radio Reference and Broadcastify may not make agencies happy. You could get a take-down notice or even worse, it is trivial to turn on encryption at the system level and you just blocked reception for all scanner listeners.

Thanks to those whose tutorials I first used getting this setup working: $20 trunking police scanner and RTL-SDR Tutorial: Following Trunked Radio With Unitrunker.

Program versions

I used a Windows 7 64 bit PC. Applications and versions used in this writeup:

SDRSharp: 1.0.0.1330
Virtual Audio Cable: 4.14
DSDPlus: 1.51
UniTrunker: 1.0.30.10

Parts list

Listed below are all the parts needed to get this project working.

Computer with some processing and memory horse power. It is recommended to have a computer with a recent Intel Core i5 processor and 8GB of RAM, or better.
Receive antenna that covers 700 & 800 MHz where P25 trunked usually resides. For an external antenna, splitters and coax runs maybe needed. The stock RTL-SDR dongle antennas worked fine for me.
Two RTL-SDR Dongles. To decode more than one voice transmission, increase the number of dongles needed.
Virtual Audio Cable. Not free but trial version available.
Radio Reference account. Premium account. If you don’t want to fork over the money, become an audio feed provider.
Recommend a USB hub. Couple years ago I picked up a Rosewill RHUB-300 USB 2.0 Hub 7-Port HUB. I recommend this hub because when the dongle is plugged in, the antenna connector is pointed up. This makes it easier to connect an adapter and a Pryme RD-98. If available, connect the hub to an Intel USB chipset on your motherboard. I’ve had far less issues using Intel based hardware.

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Jeffrey Kopcak, MBA – K8JTK