Saturday, February 14, 2009

1st WSPR spot @18MHz

The Si570 10mW WSPR beacon has reached now OH3QN, 1634km away at 17m band. Interesting to see that it received at -7dB below noise in 2.4kHz SSB bandwidth. As the WSPR threshold is -27dB below noise, this means in theory the beacon could still be seen with a power below 100µW, wow!

Also DL2NQ did receive the beacon at 80m. It is special as the antenna is just an inerted V for 40m.

Wednesday, February 11, 2009

10mW WSPR beacon at 40m is born and alive

Just to inform you about the results of the beacon experiments. After some hacking the ATTINY45 firmware of my SoftrockV9 / USB Synthesizer board, I finally succeeded to integrate the WSPR generation code. As an experiment it broadcasts on three different frequencies in the 40m band my call, grid location and TX power. 

This morning, just for fun and as a joke I connected my dipole directly to the output of the si570. A small 3 pole lowpass filter was placed in between to attenuate harmonics, the output must be about 10mW. 

In the picture you see the reception reports. Amazing that this is working. The first three lines below were reception reports by using the Softrock RXTX (1 Watt); the upper lines where the SI570 transmissions; interesting to see that HB9OAB sees a signal strength difference of 20dB.