My Ham stuff

My life as radio amateur ON1ARF

Browsing Posts tagged raspberry pi

Build your own echolink node using the raspberry pi for 100 euro.

Small unix devices like the raspberry pi, beaglebone, pogoplug and others are proving to be very usefull tools for all kind of ham related applications. They have been used in project involving D-STAR, rig-control and wspr server, for APRS node and other.

This project looks at another aspect of amateur radio: echolink.
The aim of this article is to describe how to create a complete echolink linknode using raspberry pi; complete for around 100 euro. The goal is to provide a platform to allow people to get their first experience with the raspberry pi, with interfacing computers and radios and with setting up ham infrastructure.




The hardware components needed for this project are:

  1. A raspberry pi + power + case + SD card
  2. A USB audio-fob
  3. (optionally) a USB-to-serial adapter
  4. A “digital modes” interface board (either self build or commercial)
  5. A handheld radio + (by preference) an external power-supply
  6. An external antenna

This project aims at using as much as possible homebrew equipement and off-the-shelf components.

continue reading…



It has been a couple of months since my last blog update, but that did not mean nothing was happening.


A couple of days ago, the last version of the c2gmsk modem has been synced on github. (see link here)


In short, the following things have changed:

  1. In request, the c2gmsk modem has been converted into an API (application program interface). The idea is to allow the modem to incorperated into other applications. Application that come into mind -appart of the applications of the c2gmsk package itself- are FreeDV and TheLinkBox.
  2. As a result: the “gmskmodem” application has been split into two parts: the c2gmskAPI and the c2gmskmodem itself.
    continue reading…

Hi All,


Just a small post to show that sometimes, things do not always go as planned.


Today, I have been doing some more work on the gmsk modem project. On the video that was posted, I used the raspberry pi as “sender” and the pandaboard as “receiver”; so today I decided to reverse the project and check on actual CPU-usage on the pi when receiving.

However, I ran into all kind of strange issues, all of them related to errors in the bitstream that is received.

continue reading…



A video of the gmskmodem in action using the codec2 voice codec has been made public on the web (see link below). It shows a one-way demo QSO between two radio/board combinations:

  • In the transmitting chain: a headset, a raspberry pi board doing codec2 coding and GMSK modulation, a yaesu FT-857D and two USB audio fobs
  • In the receiving chain: a kenwood TH-F7E, a pandaboard for gmsk demodulation and codec2 decoding, an USB audiofob and a small speaker
The setup is described in this drawing: