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Echolink Node Native on Linux with Svxlink, and a Cheap PTT Hardware Interface August 8, 2011

Posted by GuySoft in Crictor, diy, Electronics, Hamakor, ITU, linux, open source, programming, wireless.
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The Jerusalem Echolink Node

The Jerusalem Echolink Node (4Z7GAI-R)

Hey all,

I recently got my amateur HAM Radio license from the Israel ministry of communication. My call sign is 4Z7GAI.

I have been working on getting an Echolink node running on the Jerusalem repeater using Linux. Echolink is a closed proprietary software that lets you connect ham radios to one another and key them across the Internet. Luckily someone wrote a FOSS program called Svxlink, which lets you connect to the Echolink network on Linux., A remote radio control with an echolink server, svxlink-server and an Echolink graphical client, Qtel. I am going to explain in this post how to get svxlink compiled and working (compiling is the hard part). I will also giving out here an Ubuntu package for the lazy ones among you.

I will also add a small section on the physical connection to the radio, an old Icom IC-02AT from the 80s (around my age).

Compiling Svxlink For Debian, Ubuntu packaging and Installation

My system is Debian, ubuntu needs a few extra lines and they are supplied in section number 2. If it isn’t, here is a .deb package for Ubuntu.
Note that I am checking out the qt4 branch.
Update: svx Merged the Qt4 branch into trunk. So now it should work when checking out the trunk.

  1. sudo apt-get install libqt3-mt-dev libsigc++-1.2-dev tcl-dev libasound2-dev libgsm1-dev libpopt-dev subversion checkinstall
    svn co https://svxlink.svn.sourceforge.net/svnroot/svxlink/branches/qt4 svxlink
    cd svxlink/src
  2. sudo apt-get install libqt3-mt-dev libsigc++-1.2-dev tcl-dev libasound2-dev libgsm1-dev libpopt-dev subversion checkinstall
    svn co https://svxlink.svn.sourceforge.net/svnroot/svxlink
    cd svxlink/src
  3. Only in Ubuntu (not Debian, these lines are not needed there) type these commands:
    mkdir -p async/audio/alsa
    ln -s /usr/include/sys/asoundlib.h async/audio/alsa
    ln -s /usr/include/gsm.h async/audio/
    ln -s /usr/include/popt.h echolib/
  4. Then run:make
    sudo checkinstall
  5. Then press  2 and type “svxlink” to give the package the right name.You will have a .deb package you can install now with dpkg -i svxlink.deb

Troubleshooting:

If you are getting strange compile errors, don’t panic, its pretty normal for svxlink. Post them here, or search for them in the svxlink message archive. There are quite a few common ones.

Installing the voice files

Svnlink can speak out information on the node, for example callsigns of hams joining in or announce the time. For that you need the freely available sound files from Svxlink.
Download the the heather sound package from the svxlink sound downloads
Extract the contents (including the en_US folder inside) to the path: /usr/share/svxlinks/sounds . You may need to create the sounds folder.

Configuring Svxlink

Svxlink has many options. And detailed man pages of what they all do. The main configuration is in /etc/svxlink/svxlink.conf where you set up your callsign for the station, the RX and TX sound ports and logics. The logics let you decide if you are running a simplex repeater or a full-duplex repeater. Also you can set which modules should be used (including Echolink). Each station is unique so you will need to go over the configuration slowly and figure it out. The svxlink.conf manpage is well documented.

The echolink configuration is located at /etc/svxlink/svxlink.d/ModuleEchoLink.conf . Again, its pretty simple and there is a ModuleEchoLink.conf manpage (if you get stuck on something just comment here).

My custom hardware interface

Hardware

The circuit is simply a computer-controls relay switch. Opening and closing the audio connection between the PC sound card output, and radio mic-in.

To interface with the computer, I used my beloved Bumble-b that I posted about before. However the bumble-b is not being made anymore (we don’t know if the maker of the bumble-b, dfletcher, is dead, alive, or neither). I hope to post here later a simpler interface using a $2 usb-serial interface. But for now you can see the general idea: you could use any other computer interface that opens and closes a relay (an LPT port for example), this relay would connect the mic-in of the radio in to the speaker of the computer’s sound card, serving as a Push-To-Talk button.

The radic-mic and PC soundcard are connected to each other via an audio transformer taken off an old modem, as shown in the picture below. You can get these transformers off any old dialup modem, its easy to spot the coil on the modem board too. The transformer goes between the radio and sound card because they don’t have a common ground, if you just plug them together one would fry the other. However the radio’s speaker out and PC’s mic-in are just plugged in directly. That seems to work fine when the sound on the radio is set down low, still, you could use another transformer if you want to, it might give better results for some radios.

Custom PTT Interface for svxlink

Software

For svxlink to key using this custom interface I had to slip a few quick and dirty lines of code in to the files src/svxlink/trx/LocalTx.cpp and src/svxlink/trx/LocalTx.h .

Here is the patch. Its generally useful to look at if you have your own commands to key your custom-built PTT for svxlink. In mine I just echo to /dev/radio ‘y’ and ‘n’ in order to open and close it respectively.

Come to my new Echolink node!

I hope this helps anyone who wants to work with svxlink. You are welcome to come to my echolink node at 4Z7GAI-R that connects to the Jerusalem repeater in Israel (R1).
I connect to it now using the android app for echolink. So I can key my radio from anywhere!

Thanks

Also great thanks to strata who is on the #hamradio channel on freenode, he showed me the program and that its worth doing the painful compiling for it (it was much more painful before this blog post).

Also thanks to Geoffrey Mendelson (4X1GM). Who gave me the radios and antenna to build the repeater, and his help along the way.

Comments are welcome as usual

73 for now

Comments»

1. Richie - August 8, 2011

You sure you are allowed to run a repeater with a “Tech” license?
73 de 4Z7DIB *Richie*

GuySoft - August 8, 2011

I am not running the repeater. I am connecting to an existing one.
Also, by a strange coincidence, all Echolink nodes in Israel are run by “Tech” class license hams. There is no law in Israel about connection to Echolink since it didn’t really exist when the laws were written.

2. shlomo - August 8, 2011

very cool.

I’ll see if this works out on my ubuntu box. I’ve been using echo link (on windows) for many years; now there’s a chance I can get it to work on ubuntu.

73 de 4z5sw shlomo

3. Eric Guth - August 12, 2011

Guy,

This is very cool. However, the audio from people linking to R1 is not consistent. You need some kind of audio processing that acts like AGC but may also create a frequency response that is more two way radio rather than flat from low to high, especially for hams that are using camera microphones on their PCs. This will make some of our visitors more understandable.

73, UG

4. Rich - August 16, 2011

Guy,

Any particular reason why you decided to run the link on the ‘local’ repeater instead of the Har Gilo repeater ? Was it your intention to only provide RF coverage within the city ?

Congratulations on obtaining your Ham Radio license. Great to see the spirit of innovation and experimenting is alive and well !

73,
Rich
4X1DA

GuySoft - August 25, 2011

I was ordered by the Israel Amateur Radio Club. I think because the activity bothers them on R7. They get only a carrier signal when we use R1. Input on why would be appreciated of course.

GuySoft - September 9, 2011

Update: After Israel Amateur Radio Club (IARC) heard about this. And R1 was fixed to not send a carrier to R7, they approved the node to remain permanently on the repeater :)

5. GuySoft - September 28, 2011

Update: svx Merged the Qt4 branch into trunk. So now it should work when checking out the trunk.

6. Roque - August 30, 2013

Thanks.

7. Phil - October 23, 2013

Hi nice artical, I was looking at svxlink a while ago with the thought of a local node for this area as we have none, hit a big problem when I found that echolink does not permit foundation class licence holders in the UK to conect a radio to a computer? seems very strange as tech licence holders around the world are and I have a perfectly stable licence free 446 FRN gateway running 24/7 open to all! oh well will have to wait for my 2E0 call and run echolink on PC only untill then.
73
Phil


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