A decrease of bandwidth by a factor of 6 will increase reported SNR by
approximately 16dB.But that's just a matter of what noise reference you
use...not any real change in the signal level.If you used signal peak instead
of RMS the SNR reported would be really low....it's all relative to the value
chosen for N.
You could just as well divide the signal level by some really small number and
have 100's of dBs shown....the signal never changed though.
de Mike W9MDB
On Friday, October 19, 2018, 9:58:10 AM CDT, DG2YCB, Uwe <[email protected]>
wrote:
Frank, seems indeed to work! Just tested during RX of station KG4HF with
bandwidth of either 3 kHz or 500 Hz. See the following S/N comparison.
Astonishing!
73 de Uwe, DG2YCB
Von: Frank Kirschner [mailto:[email protected]]
Gesendet: Freitag, 19. Oktober 2018 15:48
An: WSJT software development
Betreff: [wsjt-devel] Improving S/N
One thing I haven't seen discussed on this reflector is improving the S/N by
narrowing the receiver bandwidth. It is no surprise that decreasing the
bandwidth received increases the S/N, by 10 to 15 dB, sometimes more. When I
see a station I want calling at -24 or so, I can narrow the BW and get solid
communications. This is very easy with the graphical presentation and digital
filtering of the Flex 6600, but with a little practice, could be done on any
modern receiver.
This means that, if we knew where the stations were calling at -30 or so, we
could focus on them and bring them up to the point of making contact. Since you
can't decode stations at that S/N, it would have to be done "out of band." Is
there any thought being given to setting up an FT8-only DX cluster with exact
frequencies?
What a fascinating hobby!
73,
Frank
KF6E
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