[600MRG] WSJT-X 1.9 vs 1.8 WSPR decoding test

[N1BUG]

Yesterday's release of WSJT-X 1.9.0rc2 came with this note: 
"Improved decoding performance for WSPR mode, especially effective 
at LF and MF". I wanted to put this to the test so overnight I ran 
four instances of WSJT-X:

1.8.0 on both LF and MF using the call sign N1BUG/1

1.9.0rc2 on both LF and MF using the call sign N1BUG

All spots were uploaded to WSPRnet.

Both decoders on LF were fed the same audio stream. The setup is a 
simple SDR providing I/Q input to a physical sound card, HDSDR 
software output into a virtual audio cable, both versions of WSJT-X 
taking input from the output of that virtual cable.

The MF setup was the same except using a different SDR feeding a 
different physical sound card.

I used identical settings in all four instances of WSJT-X with the 
exception of different input audio source (virtual cable) for LF and MF.

All of this was running in Windows 10.

I watched incoming spots very closely for the first several hours. 
There was not much activity on LF at the time but on MF I saw 1.9 
decode many WSPR transmissions that 1.8 failed to decode. Some of 
these were extreme weak signal down to -32 with barely visible 
traces on the waterfall. Others were not with some clearly visible 
and decoding up to -23 in 1.9, yet no decode in 1.8 despite being 
very clear on the waterfall in that version. I did not see a single 
instance where 1.8 decoded something that 1.9 failed to decode.

This morning I took a quick look at statistics:

MF - During a 12 hour period ending 1145z, 1.9 decoded a total of 
933 WSPR transmissions while 1.8 decoded only 883.

LF - During a 12 hour period ending 1150z, 1.9 decoded 253 WSPR 
transmissions while 1.8 decoded only 183.

In all of this I do not see any obvious spurious decodes from either 
version. No strange call signs or stations displaced on the map from 
where you would expect them to be.

I was not expecting to see such a large difference. I make no claim 
that this result is representative of what others will see. I am 
simply reporting the results of an experiment carried out here.

73,
Paul N1BUG