That’s become a funny game during our last local net on 2 meters.
The screenshot you can see here behind is an online tunable radio working on 80 40 and 20 meters band from Holland.
We did enjoy comparing the delay beetween our receivers and the live feed coming form this web radio, and it was nice to discover that the difference was just half a second or less.

We did also test transmitting and getting heard by the remote station, and was interesting to see the waterfall differences on incrementing the output power.

But the most interesting thing was understanding what is behind this web page….

First of all this is not a common remotely tunable radio as you may have had the opportunity to play, there are many remote radios on the net but rather this is a Software Defined Radio. Let’s call it a Virtual Radio.

A Software Defined Radio, is a computer program, that emulate a complete radio, where tipical components like filters, mixers, amplifiers, demodulators, detectors etc have been reproduced by software programmed libraries. Input Output is demanded to commom sound cards, and a minimal RF frontend is provieded.

The University of Twente in Holland has published an SDR web interface that allow you to tune the radio, along to other concurrent users, by simulating a virtual receiver. It means that what you tune, is not heard by others, but only from your pc.

Like other virtualization technologies, a shared host platform is supplied (here is a common old-fashion pentium III PC running linux), and from this host you can load your own virtual exclusive radio and tune the waves via the supplied W3DZZ trap-dipole for the 80 and 40 meters

To load this sdr radio, requirements are Java Browser Plugin installed and access through TCP port 8901.

We can just say Bravo! to the hams that promoted this experiment.

Link to WebSDR on 20m, 40m and 80m

more Software Defined Radio Links, SDR Programs and products