Check-out this work by G3ZIL and others ===> *https://www.researchgate.net/publication/319903566_Improving_HF_Band_SNR_from_analysis_of_WSPR_spots <https://www.researchgate.net/publication/319903566_Improving_HF_Band_SNR_from_analysis_of_WSPR_spots> * 73 Dick/w7wkr presently at CN97uj