Websdr Robotic Radio at K7UEB, Walla Walla University Amateur Radio Club

Websdr is web server software that allows many users to listen to different parts of the radio spectrum over the web.  It was written by Pieter -Tjerk de Boer, PA3FWM.  The server at K7UEB is not only available for users all over the world to listen to, and use for experiments; it is also a robotic radio, spotting stations on the digital mode PSK31 (and maybe soon RTTY and PSK64)


The hardware consists of a Dell GX620 with an M-Audio Delta 1010LT 96KHz audio card connected to three Softrock receivers.  All three receivers are connected in parallel to a Hustler 4BTV vertical on the roof.  The hardware resides at the K7UEB club station on the campus on Walla Walla University.  Presently, the 20 meter SSB receiver has very poor sensitivity, and the 40 meter receiver has an intermittant problem with the oscillator quitting.  Maybe I'll get a chance to fix those sometime.


The heart of the robotic radio is the software.  The software is running on Ubuntu Linux version 10.04.  Administration of the software is accomplished remotely over NX using Google's neatx server which allows remote X sessions that can be connected to, and reconnected to at will, from most any client computer connected to the network. 

Audio routing is handled by the Jack Audio Connection Kit, which allows the audio to be split and sent to several different processes that each need it for their purposes. 

The start up script I use shows the detals of how all the software is started, the options used, etc.

Websdr uses OSS sound (/dev/dsp), but the developers of Jack firmly believe that OSS should be depreciated, so there wasn't a good way to connect between Jack and the Websdr server.  Pieter suggested I could use named pipes to couple the output of Jack to the input of websdr, so I wrote jack-fifo, a C program which does that.  It is available under the GPL license for you to examine or use too, if you wish

There is a lot of QRN from powerlines at the K7UEB QTH, so I added a noise blanker into jack-fifo to try to remove the noise.  It works pretty well, but there are still more improvements I want to try with the nosie blanker.

Spotting Robot

The spotting robot uses several pieces of software, and several instances of all that software, for the different bands/modes that are being spotted.  Sound from Jack is sent to sdr-core (DttSP), which is the same DSP software that the Flex radios use.  The output of sdr-core is coupled to Fldigi which demodulates the digital signals and sends the spotting data to the PSK Reporter web site, which displays it on a map and in other ways.

Rob "dot" Frohne "at sign" wallawalla "dot" edu