This afternoon, Domenico IZ7SLZ and Riccardo IW4DXW were both sending EbNaut, using alternate 15-minute slots on the same frequency 477.695 kHz. The six character messages consisted of their respective callsigns and were encoded using the 8K19A polynomial with 560 one-second symbols.

 

IW4DXW was first successfully decoded here at noon after 12:15 UT, whereas IZ7SLZ, being much further south, started coming in only after 15:30. The daytime signals were weak but rather stable, and SNR would surely have been better in a quieter receive environment than mine. During the early evening, signal strength literally picked up tens of dBs, but at the same time propagational phase variation became much worse, severely affecting symbol error rate. Interestingly, there was also a variable carrier component beneath some of the transmissions, either due to some asymmetry in the PSK modulation, or to unidentified co-channel carrier interference.

 

An overview of receive results, as well as zipped phase plots and wav files, can be found in the folder

 

Thanks very much Dom and Ric for this interesting test, and also to Wolf for providing frequency lock capability with the latest SpecLab version.

 

Best 73,

Markus (DF6NM)