Multi PSK The experimental PSK10 mode is designed to assure communications with weak ratio Signal-to-Noise until 0.013 (-19 dB) with 2% errors, so a signal 77 less powerful that noise. The equivalent morse speed is 18 words/minute,  the PSK31 mode is designed to assure communications with ratio Signal-to-Noise until 0.062 (-12 dB) with 2% errors, so a signal 16 less powerful that noise. The equivalent morse speed is 37 words/minute in capital and 51 words/minute in small letters (2.8 times PSK10 speed). These two modes can extract weak signals in strong noise. However the principal problem is their bad behavior under radio-interference (at a certain point, several signals may arrive, each one with a different phase). Sometimes there is no interferences and there are few errors and sometimes it's difficult to understand the displayed text! Compiled by F6CTE