[600MRG] Receiver bandwidth for WSPR

[Edward R Cole]

Just for comparison, my 80m noise floor using 2.8 KHz bw with K3 
connected to inverted-V is running S3-4.  There are times it reaches S5.

This is how WSPR and JT65 provide their super sensitivity.  They run 
FSK with a maximum shift of about 180 Hz and use DSP filters to 
detect the tones with under 10-Hz RBW.  SNR improvement by reducing 
bw from 2.5 KHz to 10-Hz is 24 dB.

Reduction of bw from 2.6 KHz to 400-Hz is exactly = 10Log(0.4/2.6) = 8.1 dB
Probably your s-meter lies! ;-)  Did you disable your AGC for this measurement?

But no doubt narrowing bw helps reject noise.  Best SNR will result 
when Rx bw is same as signal bw.

At 07:44 AM 3/21/2014, Kenneth G. Gordon wrote:
>On 21 Mar 2014 at 9:50, jrusgrove at comcast.net wrote:
>
> > I don't know how Joe
> > is making the calculation but I can tell you that bandwidth size 
> does matter.
>
>Most definitely true. Even in the very simple, and MOST annoying, case I am
>experiencing here: on 80 meters, my constant noise level at the moment is
>20db over S-9 when my receiver is in the "SSB bandwidth", about 2.6 Khz.
>
>When I drop the bandwidth to around 400 Hz, the noise level drops to S-7, a
>difference of almost 40 DB.
>
>So, yes, bandwidth can make a HUGE difference in S/N ratio.
>
>Ken W7EKB
>
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73, Ed - KL7UW
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