© Christoph Petermann DF9CY 2008/2009

Last Revision: 22 September 2009

WSPR Weak Signal Propagation Reporter

In March 2008 Joe Taylor, K1JT, released a new piece of software called WSPR (Weak Signal Propagation Reporter). Its digital mode is called MEPT_JT (Manned Experimental Propagation Tests, by K1JT)

In the internet I fell over a lot of notes on WSPR and I decided to have a closer look on this. I downloaded the piece of software and installed it. Everything is well described and I do not have to repeat it here too.

I used my Kenwood TS690s for reception of the WSPR signals. But before I had to calibrate the receiver to find the correct frequencies. But this can easily be done using AM radio transmitters where the centre frequency normally is very well defined. For example I took a signal on 9.350 MHz and if you tune to 9.349 MHz you should hear a 1 kHz tone in USB (upper side band). I measured with a spectrum program and saw a 1030 Hz tone instead of the expected 1000 Hz. This offset of 30 Hz I had to offset the receiver (and later the transmitter).

I immediately could see the typical 2 minutes signals in the spectrum display, but I had no decodes on these. I found out that the sound card was not set to the correct sample frequency of 48 kHz. After having done so manually I could also decode the signals. Amazing what came into my receiver.

Transmitting now was easy. I set the TS690s to its lowest possible power, which is 1.9W (=33 dBm) on 30m. I let it running for a while and then I saw in the internet logger, that my signal was received all over the world and there were even reports from Australia.

I used my 40m monoband dipole for the tests. It is totally unmatched on the 30m band. But even this worked.

WSPR with Softrock 6.1 RXTX (0.9 watts)

In September 2009 I got my little softrock transceiver working with WSPR. The software setup for this is described here. It does a phantastic job on 40m. The little transmitter with 950mW output has been heard worldwide from my tiny 40m dipole.

4 September 2009: VK6BN copied with the softrock.

5 September 2009: VK6WS and T61AA "softrocking"

The transmitted 0,9watt signal in Australia !!

21 September 2009: 18059km into New Zealand - Does it go further ???

A map

This map shows a number of places, where my 2 Watts signal on 30m has been received. The time running this "beacon" was only abaout 2 hours. Australia is out of this map. (Map created with Ham radio Deluxe)

Download and Links

You will get WSPR at K1JT's site

More information and databases are at WSPRnet.org

Some technical details

MEPT_JT uses a 4 tone FSK modulation with strong FEC (Forward Error Correction). The tones are separated by 1.46 Hz.

Bandwidth used is ca 6 Hz and the transmission time is 110.6 sec. The length of a single tone is 0,6827 s and maximum allowed drift is about 1 Hz. (It seems some higher drift is still OK ??)

Some images

WSPR on 30m, where my antenna not matched to.

WSPR on 40m. This band works better for me.

Screenshot of the logger. Some of my transmissions received around the world.

At the end

I do not know, how long WSPR will "live" ... It is a sort of an interesting experience. It may be interesting for 6m propagation studies since the high power TV transmitters are closing down in Band I.