How do I get my DMR recordings?

 

Kraken is coming and we all need to prepare for its arrival.  On Tuesday October 19th 2021, Steve K2GOG was invited to the North Star Digital Net to give a quick chat about what does it do and why its important for the future within the broader topic of "software defined radio".

A few people who could not attend the live discussion had asked Jim WA2UMP and Steve K2GOG to see if they could record the audio presentation.   This is a fun problem that needed to be solved first to start this article, so read onward!

How do you record DMR audio?

Steve K2GOG planned to use his Alinco DJ-MD5XTG to talk via his hotspot which reaches the Brandmeister 31630 (STEM) talk group.  A nice feature with this radio, as well as the popular Anytone AT-878 series of radio, is that it can record transmit and receive audio with timestamps and by who was speaking.

Its easy to scroll through recorded audio files one by one or play all your recordings on a loop to play them all in order. This could be helpful if you thought you may have missed some important scheduled discussion or activity on your favorite talk group.

One annoyance is that the recordings save to internal memory on the radio instead of a micro SD card, like on radios such as the D-Star focused Kenwood TH-D74 or the Fusion based Yaesu FT-5DR. 

Both of those radios and even the Icom IC-705, all require the user to remove the SD card from the radio to access recorded audio but that makes it really easy to access those files  on your computer and send them to someone to share interesting transmissions like during a satellite contact. 

In the case with the Alinco and Anytone, you need to connect up a cable to your computer to access the recordings but you can not pull those files off which is super annoying. The manufacturers software seems to lock this function out but would otherwise clearly support this as pictured below.

If you click any of the files listed in photo above, the recording simply plays through the radio speaker but we are no closer to sharing the recordings.

The Alinco DJ-MD5 series of radio uses a simple USB micro cable to program the radio but does not output audio.  The way to solve this problem is to use the headphone port on the Alinco which uses the standard 3.5mm plug found on most all consumer headphones.

Using a 3.5mm stereo to stereo cable, the other end plugs right into the microphone jack on your computer sound card.  If you have a modern laptop which uses a TRRS (Tip, Ring1, Ring2, Sleeve) style connector, you may instead need to use a USB sound card as mentioned in Steve's explanation video below.

Now that we have that problem solved, you can use a program like Audacity with the sound activated record function enabled to "re-record" the audio from the radio to your computer.  While this takes a little while to do, it lets you easily stitch together the audio segments you want with no gaps. 

If you are over a certain age where you may remember double cassette recorders, this activity may bring back memories of less technological days when you had to get creative to make a mix tape from "borrowed" cassettes or maybe songs off the local broadcast station.

Hopefully this modern solution may give you some ideas on getting more from your DMR radio.

Getting back to Kraken

After all that, now we can finally get to the recording you might have missed! 

Here is an MP3 recording mostly of the segment from Steve K2GOG.  

It sounds like he missed a few parts but is otherwise complete. It looks like a time intensive operation to click on all recordings in order, so bear that in mind if you wish to do something like this yourself.

The recorder function works on any "over the air" DMR signal, so using it also to record simplex activity like what took place during the NEARFEST on US national DMR simplex of  446.075 MHz on time slot 1, color code 1 and talk group 99 is another idea.   

But, if you plan to record audio from Brandmeister you can also just use the "Hoseline" function and route that audio from a talk group into Audacity just as easily using virtual audio cables. 

And with that, I hope you are looking forward as much as Steve is to getting the new Kraken once its starts shipping in March 2022.

February 11th: Would you like to meet a super hero or two?

Hudson Valley Digital Network (HVDN) is proud to offer an exciting event open to any current or aspiring amateur radio or electronic hobbyist regardless of any other memberships on February 11th 2019.

Join us in welcoming newly elected ARRL Hudson Division Director, Ria Jairam N2RJ and Sean Swehla KD2HGY of the Squidwrench maker group for an evening of education and fun in Rhinebeck, New York starting at 6:00 PM.

Event Details:

Doors to the community space at CO. located at 6571 Spring Brook Ave in Rhinebeck New York officially open at 5:30 PM with the presentations starting a little after 6:00 PM. Light refreshments and hot/cold beverages will be served. The event concludes at 7:30 although the space is available for discussion after and up until about 8:30 PM.

HVDN Presenters: Ria Jairam N2RJ & Sean Swehla  KD2HGY

Ria will share details on where she thinks ham radio is headed, how to be part of it and how to make the hobby interesting to a wider audience.

Sean will talk about the upcoming oscilloscope build project event that Squidwrench and HVDN have collaborated on. Details on this pre-registration only event can be found at:
https://www.eventbrite.com/e/build-it-oscilloscope-signal-source-tickets-53349617141 


Where Do I Go?

Rhinebeck is home to many unique attractions ranging from the home of the 200+ year old Dutchess County Fair  and Beekman Arms which is the oldest Inn in the United States.

There are many more modern attractions, one of which is the very sleek CO. co-working office and community space just across from the fairgrounds. It should be easy to find.

Anyone who is a professional "work from home, with a laptop" sort of person may also be provided a complimentary pass to use the facility for the later part of the afternoon prior to the start of the HVDN meeting.  Please contact Steve Bossert K2GOG and co-founder of HVDN at steve.bossert@gmail.com or at 1.914.573.1799 for details.

How To Guide: Satellite Based APRS iGate

There is so much amazing activity these days surrounding satellite and software defined radio (SDR), but there are not many clear and current guides for those interested in creating receive only gateways to send satellite born APRS signals over the internet. Let's change that.

APRS & Satellites (and balloons, drones, etc)

Currently there are three active satellite based digipeaters in low earth orbit. The International Space Station (ISS), PCsat NO-44, and SAT NO-84 all operate on 145.825 MHz.

There is also a fourth APRS satellite named FalconSat-3 that was turned over from the United States Air Force in 2017 for amateur radio use, but is operated on 145.840 MHz and requires a little more work to use. There are other amateur digital mode satellites in the planning stages.

Image Courtesy of  http://aprs.org/outnet.html

What is an iGateway?

An iGateway is nothing more than a radio receiver that is connected to the internet. Signals received by the antenna are passed from the radio over the internet.  The iGateway is designed for digital or data signals and not voice however. Websites such as findu.com and aprs.fi are two examples are where the benefit of igateways can be shown and show APRS data.

There is also the Othernet (Formerly known as Outernet) project that sends information from its ground station back up towards different satellites that "datacast" to special receivers such as the Dreamcatcher. Properly addressed APRS messages are in turn broadcast over this separate satellite network. This is not the same as an iGateway, but does add some other unique potential.  For an amateur to route a message with APRS through one of the mentioned satellites earlier, one must use the path of "OUTNET" instead of "ARISS".

General users of APRS for ground based modes typically leave the path as WIDE1-1 or WIDE2-1, but those interested in satellite communications must use the alternatives listed since a satellite works differently from a propagation perspective to ground based or even low altitude aircraft or balloons.

How To:  SDR & Raspberry Pi iGateway

To create an iGateway you will require:

• An inexpensive USB SDR

• Raspberry Pi Computer or other similar device

• Antenna capable of overhead reception

• Various cables and stuff for your installation

There are way too many variables on antennas and cabling specific to every installation so we will keep this brief and skip that part. The shortest run of coaxial cable from antenna to radio is needed. The highest and clearest view towards the horizon in as many directions as possible is required for optimal reception when considering setting up a iGateway.

The satellites we will be monitoring pass over most locations about 3-5 times every day for just a few moments, so it's possible a APRS capable satellite will pass over once every 60-90 minutes.

Lets setup the software bits and bobs....

The main goal of this article is to only share the steps for configuring software to get a SDR dongle working with a Raspberry Pi.  These steps can also work for those looking for alternate uses for SDR based hardware such as the now out of date L-band focused Dreamcatcher v 2.03 boards that were replaced with the newer Ku-band Dreamcatcher v3 and likely could be used too.

The real magic here is the software and how it will all work together.

First step, is get a working operating system on your device of choice such as the Raspberry Pi or Dreamcatcher v2.03. Most of these instructions will work for other linux based computers but is not the focus of this article.

Please run sudo apt-get update and sudo apt-get upgrade first to ensure your operating system is current and has most all of the popular packages installed for general use before continuing.

Second step, involves setup of Dire Wolf which translates sound to packet decoding. Run the following on your device to install it.

sudo apt-get install libasound2-dev
git clone https://github.com/wb2osz/direwolf
cd direwolf
make
sudo make install
make install-conf

Next, you need to configure the operating system to take virtual audio from an inexpensive SDR dongle and pass it to direwolf.  Go ahead and plug in your SDR dongle to your raspberry pi. If you are using a Dreamcatcher, there is no need since the SDR is part of the board already!

sudo apt-get install cmake build-essential libusb-1.0-0-dev
cd
git clone git://git.osmocom.org/rtl-sdr-git
cd rtl-sdr
mkdir build
cd build
cmake ../ -DINSTALL-UDEV_RULES=ON -DDETACH+KERNAL_DRIVER=ON
make
sudo make install
sudo ldconfig
sudo reboot

Let's pause for a moment and test the SDR to make sure its recognized.

run "rtl_test"  and ensure you get a status update like this before continuing. This shows that the SDR is being recognized by your Raspberry Pi, Dreamcatcher 2.03 or other single board linux computer.

Now we need to configure Dire Wolf and the best way to do that is copy some of the great work that Keith G6NHU has compiled. Head on over to his interesting site here:

http://qso365.co.uk/2017/02/a-guide-to-setting-up-an-aprs-receive-only-igate-using-a-raspberry-pi-and-an-rtl-sdr-dongle/ 

The only basic change you need to make is to select the correct frequency. In the United States much of the APRS activity is on 144.390 MHz, but since we are interested in satellite based APRS, change it to 145.825 MHz instead.

What did you say about balloons?

Perhaps you may tire of the same general activity on APRS terrestrial activity or even what may be bouncing off a satellite.  The next logical thing to look into would be tracking a balloon of some sort.

Taner DB1NTO has a new product out to cater to people looking to track something that can only carry a very light weight device.  He calls it PicoAPRS Lite and should open up lots of possibilities to experiment with alongside perhaps with a portable version of an iGateway connected via cellular hotspot.

If anyone in the Hudson Valley is interested in experimenting with tracking objects other than a house which does not move much, or a car, lets start talking.

The STEM (31630) DMR talk group seems a logical spot as well as the AMSAT (98006) talk group, so lets make something happen here when spring time arrives!

• More about STEM 

• More about AMSAT

Visit the HVDN Activity Calendar to learn of upcoming discussion, projects, meetings and events 

Happy Monday Again!; Ashford School and ISS Make Contact

The front gate to Burger Hill at Drayton Grant Park in Rhinebeck, New York was closed (and locked) at 8:45 AM this morning, so a quick decision to either quickly go home or find an alternate location to record the 9:05AM rescheduled ISS contact with a school in Ashford, CT was needed.

One of the many student questions that Serena Auñón-Chancellor answered included important ion propulsion technology that may one day take Earthlings to Mars. More below including recordings!

Ion propulsion will be important in getting to Mars - Serena KG5TMT

Tracking the ISS

Orbitron software was used to track the International Space Station. Combined with the software defined radio program, SDR#, its possible to keep the frequency locked on to accommodate for slight drift called the "Doppler Effect".  At VHF ((145.800MHz), the Doppler effect is not as pronounced compared to higher frequency, such as at 445 MHz. 

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Recording location was far from optimal for best line of site on the grounds of CO. in Rhinebeck on such short notice.

The Ashford Band YouTube channel has shared a video of the setup and ultimate discussion with Astronaut Serena Auñón-Chancellor M.D, KG5TMT.

Reception site of K2GOG in NY and KM1Z down-link site for ISS in Connecticut

YouTube link jumps to 41:50 into the 56:00 video where the actual contact between KZ1M and NA1ISS, operated by Serena.

To both see and hear the down-link signal from the International Space Station, HVDN has two files:

• MP3 Audio File - 10/22/2018 - NA1SS & KM1Z (Ashford, CT)

• IQ Baseband Recording - 10/22/2018 - 145.000 MHz to 146.000 MHz (Caution 2 GB!!)

The HVDN files are only “one way” because line of sight from the ISS to where the recording took place was too far away from where KZ1M was located.

Here are some past articles for additional reading:

• SDR: Let's Walk To The Space Station?

• Happy Monday!: ISS & STEM Academy Make Contact

• Amateur Satellite Basics: Where, When & What to listen for

Register for updates for the latest from the HVDN Notebook

Happy Monday!: ISS & STEM Academy Make Contact

On July 2nd 2018 at just past 11:30 AM was a scheduled contact between the International Space Station and the Pearl technology STEM Academy in Peoria, Illinois. Students submitted questions in advance that astronaut Serena Aunon was going to answer by using the space stations amateur radio equipment.

“Nothing beats waking up on a technological marvel and then starting the day off with an antique method of navigating. Sextant Operations from @Space_Station! Still considered a potential backup method of navigation for future vehicles…” said NASA astronaut Serena M. Auñón-Chancellor on her Twitter

Since New York where HVDN is located was in the general foot print of the space station orbiting overhead at 200+ miles high on its way over Peoria, here is a brief recording of some of the questions asked before the space station got out of range.

Recording:  NA1SS operated by Serena Aunon answering questions facilitated by W9DWJ

The reason only one side of the conversation was heard was because the ground station in Illinois is too far to hear directly on VHF spectrum in New York directly.  

The ground station setup at the STEM academy was transmitting on an up-link frequency to the ISS of 144.49 MHz and the ISS was transmitting back down on the 145.80 MHz down link. 

Start and end positions on where the ISS was first heard and when it was out of range.

It is fantastic for students to be able to leverage technology to have real time contact with the space station and to instill an interest in science, technology, engineering and mathematics at an early age.  Serena is a great role model for younger generations to see what they can be when they grow up.

Amateur radio allows anyone to experiment with this hobby, be they young, old, male, female, technical, non-technical, English speaking or otherwise.  There is much that can be learned with each other and HVDN plays an active part in the Hudson Valley area of New York in fostering interest in emerging and exciting parts of amateur radio.

Here is the radio used to record the ISS contact.

HVDN has recently launched the STEM Talk Group available on the Brandmeister DMR network which uses DMR technology to create easy and clear communications globally. 

More information can be found at the below link and perhaps this great resource can be used to connect explorers, astronauts, engineers, or anyone else who can share unique insight about amateur radio, what its capable of and how it can influence future generations to better communicate. 

• More about STEM Talk Group 31630

• More about Astronaut Serena Aunon

ANNOUNCEMENT: On Saturday July 6th, Steve K2GOG will be taking a ride in a hot air balloon as part of the Balloon Festival at the Dutchess County Fairgrounds in New York. Anyone interested in arranging contact via TG 31630 with him, can listen on TG 31630 between 6:00 AM and 8:00 AM New York time. He will be routed on to the network via the N2MCI repeater located in Kingston, NY.  Steve's location will also be found on the aprs.fi website under the N2HVD-11 call sign. He will also be making direct contact on suggested analog or digital frequencies too on 2m, 1.25m, and 70cm below

• 146.52 MHz Analog FM
• 223.500 MHz Analog FM
• 446.00 MHz Analog FM
• 446.075 MHz Digital DMR (TG 99, CC1, TS1)
• 145.790 MHz Digital DMR (TG 99, CC1, TS1)