Friday, October 17, 2008

Playing with WSPR on 40m

Picture 1.pngRoss, (ham call T61AA), has prodded me to try the low power radio mode called WSPR.

The software, for Windows, alternately listens and transmits a slow pattern with lots of error correction.

You can see where you've been heard here, and a pretty map.

(For some reason, my Grid Square is wrong and I've ended up in Siberia for the moment). Fixed now.

Picture 1.pngThe software, which is partially written in Fortran, is available at the WSJT Home Page.

The protocol is described here.

I'm running 20W (+43dBm) on 40m at 7.0386Mhz and have been heard 14,763km, 13,435km, and 12,991km away. Awesome!

Anyone know of a Mac port of this?


It's after 1am, I've been trying to install or build wsjt on Ubuntu Hardy but it turns out that it doesn't work.

Update 2

Thanks to G4ILO (a great site by the way), I'm now running with wspr on ubuntu 8.04. At this point I'm experiencing some crashes with the USB audio to a Signalink USB device.

Update 3

In an effort to solve the USB audio problems, I've now moved to Ubuntu 8.10 beta. I'm talking to the USB audio interface as /dev/dsp1. It works for a while in applications such as fldigi but the incoming audio (as shown on the waterfall) pauses and errors such as "PortAudio error device unavailable" or "PortAudio unanticipated host error" are displayed. After a short pause, audio continues.

The good news is that wsjt is available via apt-get and does seem to work for a while:

Having said that, it seems flaky and sometimes needs to be re-launched to get it started.

Update 4 - the solution!

The dodgy audio problems seem to have gone away now that I have plugged the USB audio device directly into the PC rather than going via a USB Hub.

Update 5 - We make contact!

Ross T61AA and I both left our beacons running last night and both I heard him

2008-10-21 14:48 T61AA 7.040111 -17 0 MM21eo +50 100.000
VK2TPM QF56of 11636 7230

and he heard me

2008-10-21 13:42 VK2TPM 7.040107 -26 0 QF56of +43 19.953
T61AA MM21eo 11636 7230

It looks like from 12:14Z to 13:42Z there is some sort of path between us.

I'm running 20W and he's on 100W.

Great stuff!

My best reception of you was -9 sig to noise, his best reception of
me was -22 but I could run a bit more power.


Anonymous said...

You now appear on thee map in the right place, probably, as you said, the original bogus grid was cached and confused the issue.

Hope you have fun with it, I have now been playing with it since April.



Anonymous said...

You could try the WSPR binary I made for my Asus Eee PC. You never know...

Peter Marks said...

Great stuff!

For the sake of others, here's the issues and solutions I encountered.

"ImportError: cannot open shared object file"

Solved by installing via synaptic package manager.

"ImportError: cannot open shared object file"

I have and tried a sym link but there's a missing symbol.

When I figure it out I'll post the solution.

Peter Marks said...

Got it working. Grabbed a binary of the latest gFortran from here and stuck the library in /usr/lib and it looks like it works.

Many thanks!