some thoughts on digital signal processing in amateur radio ...
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.