Tag Archives: MARCS-IP

Ohio Section Journal – The Technical Coordinator – August 2016 edition

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.

You can receive the Journal and other Ohio Section news by joining the mailing list Scott has setup. You do not need to be a member of the ARRL, Ohio Section, or even a ham to join the mailing list. Please sign up!

If you are an ARRL member and reside in the Ohio Section, update your mailing preferences to receive Ohio Section news in your inbox. Those residing outside the section will need to use the mailing list link above.
Updating your ARRL profile will deliver news from the section where you reside (if the leadership chooses to use this method).
Go to www.arrl.org and logon.
Click Edit your Profile.
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Click the Edit Email Subscriptions tab.
Check the News and information from your Division Director and Section Manager box.
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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

DSCF5081 K8JTKHey 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 DMR Logo 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. Tytera MD-380 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 WSJT-X Conversation 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 Yaesu DR-2Xrepeater 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/.

Raspberry Pi 3I 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

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

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.