Further, given that HamCAP is just a convenient front end to VOCAP I
assume that it is using the manmade noise level of -145dBW/Hz in 1Hz
BW. Over and above this are all the other QRN noise sources at your
Reasonably easy copy can be assumed as +10dB SN for SSB and a lot
less for CW.
S-numbers are meaningless, they depend upon many things including
antenna gain or loss. A low noise receiving antenna won't
necessarily give you an S9 signal but a good SN. On the other hand
a good S9 signal might be fighting with S8 thunderstorm QRN and a
If I use my 30M antenna to listen on 40M the band seems quiet but I
can still hear the signals well. convert (match) that same antenna
to 40M and signals increas in strength by many S-points but so does
the QRN, no improvement in SN.