[600MRG] Inconclusive Pre-Sunset N1BUG JT9-2 Results

[N1BUG]

Thanks for the continuing reports Andy, and thanks to all other
participating stations.

Actually your SNR reports make perfect sense. SNR is reported as the
signal level in a 2500 Hz bandwidth. This should not change between
modes. Therefore with the same SNR measuring algorithm in the
decoding software, SNR should be the same for both modes when both
can decode the signal. What you are seeing appears to be just that,
with perhaps a bit of QSB influence as expected.

The slower mode should be able to decode 2 to 3 dB further into the
noise compared to the fast one. The theoretical limit for JT9-1 is
27 dB. JT9-2 should be able to decode 2 to 3 dB less than that, so
-29 to -30.

I actuality, I believe the SNR calculation algorithm is not quite
the same between the two programs, so I would be cautions trying to
compare SNR directly. Some of the results I have seen tend to bear
out my hunch that the respective relationship doesn't end up being
the same on all receiving systems. This has probably led to much
confusion as people try to compare the modes.

I believe a better measure of one mode against the other is simply
this: is the slower mode able to decode the signal more often or
under more marginal conditions than the faster one. That is why I am
running this test, in an effort to determine whether this is the
case. There is mounting evidence that JT9-2 is able to get the
message through more often than JT9-1.

73,
Paul N1BUG



On 12/12/18 4:53 PM, Andy - KU4XR via 600MRG wrote:
> I started seeing traces of signal in the waterfall at 21:00 UTC - 7 minutes ater sunset at N1BUG, and 82 minutes
> before Sunset at KU4XR.. The first decode of JT9-2 at 21:18 UTC is still an hour Pre-Sunset here.. Decodes of 
> both JT9-1, and JT9-2 have occurred consistently since.. Skywave component of course affecting Pre-Sunset
> results.. Distance between stations is too far for daytime / groundwave reception.. 
> SNr reading is raising an eyebrow here, however I do not pretend to understand.. Both softwares receiving the
> exact same audio feed, from the same radio.. I expected to see Higher Number SNr for JT9-2 compared to JT9-1
> 
> 2118 -28  0.8 1350 2  VVV N1BUG 2
>            
> 2124 -26  0.8 1350 2  VVV N1BUG 2
> 2126 -25  1.8 1350 @  VVV N1BUG 1
> 
> 2130 -26  0.8 1350 2  VVV N1BUG 2                                                                  
> 2132 -26  1.8 1350 @  VVV N1BUG 1 
> 
> 73 all:
> Andy - KU4XR