W8TOD's blog

I have.

Playing this evening with mixing white noise with the output of an IQ WSPR instance and viewing it on HDSDR. I adjusted the mix so that the decode was showing me at "-29 dB" and decoding reliably. The trace was just barely visible on the WSPR waterfall. Out of curiosity I brought up HDSDR and tuned the signal and the attached is what it looks like. An unexpectedly prominent spike poking up out of the noise. Using the MDS methodology and measuring in a 500 Hz bandwidth I found this signal to be +6 dB S+N/N as measured on an RMS voltmeter at the audio out terminals.

I am running a GPS-disciplined Softrocks RXTX from Singapore on 20 meters at 14.0975. Details of the GPS reference modification are here:

http://groups.yahoo.com/group/sdr-users/message/36

There is a spirited discussion on the Softrocks forum concerning the legality of WSPR transmissions under FCC rules. In this discussion one person has complained about "high power, continuous WSPR transmissions", especially on 40 meters. Out of curiosity I took a look at recent database postings and it does seem that there is a great deal more power being used than is necessary in some cases.

There is one guy running 1000 watts! 7 running 50, 9 running 20.... etc. There is simply no need for such power levels on HF WSPR.