LF: Re: WSPR -2 SNR

[<jrusgrove@comcast.net>]

> My receiver bandwidth is 540 Hz.
It has been shown in the past that a receiver bandwidth significatly less than 2500 Hz artificially 
inflates the reported WSPR s/n.
Jay W1VD  WD2XNS  WE2XGR/2

----- Original Message ----- 
From: "Roelof Bakker" <roelof@ndb.demon.nl>
To: <rsgb_lf_group@blacksheep.org>
Sent: Monday, March 18, 2013 10:07 AM
Subject: LF: WSPR -2 SNR


> Hello all,
>
> On the WSPR website,
>
> http://physics.princeton.edu/pulsar/K1JT/wspr.html
>
> I find this statement:
>
> > > > The program can decode signals with S/N as low as -28 dB in a 2500 Hz  bandwidth. 
> > > > <<<
> I have been looking at decodes on WSPR Spots
>
> http://wsprnet.org/olddb
>
> and it appears that on bands from 160 m and up a SNR smaller than -25 dB  is a 
> bit rare.
> On 630 m these low level decodes are found more often, though decodes with  an SNR of -30 are 
> rare.
> In the nigh of Saturday to Sunday, I had 14 decodes from WG2XJM.
> Two of these showed a SNR of -33 dB.
> I have never seen such a low SNR before and a search through the WSPR  Spots database showed a 
> decode from a French listener of WG2XJM with an  SNR of -31, which is the lowest SNR I could find.
> As far as I know the bandwidth of the WSPR decoder is set to 200 Hz, so as  long as the receiver 
> bandwidth is larger than 200 Hz, decoding should not  be effected. My receiver bandwidth is 540 
> Hz.
> So, has anyone an idea what is the cause of these low level WSPR decodes.
>
> Best regards,
> Roelof Bakker, pa0rdrt