Re: LF: what causes this on wspr

[John Langridge <jlangridge@sbcglobal.net>]

>do you  see  this  pattern from  your   SDR ? 

When I am transmitting and subsequently overloading the SDR, yes.  It has similar, regular spaced sidebands away from the center freq.  In fact, if you go to my QRZ page bio, the topmost picture is a grabber shot of my WSPR signal signal overloading the SDR along with another WSPR station about 200 miles north of me.  10w ERP....  the RX antenna at 1 mile is a resonant, well match toploaded vertical (about 10m tall) so its swamped with signal and does not deal well with it.  

This may not be the same situation but it sure looks familiar as overload.

73!

John KB5NJD / WG2XIQ

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From: Graham <g8fzk@g8fzk.fsnet.co.uk>
To: rsgb_lf_group@blacksheep.org
Sent: Wednesday, July 1, 2015 1:56 PM
Subject: Re: LF: what causes this on wspr

Tnx John

 

The over drive  option   has a  flaw ,as far as I can see ,  as  to  where  the  frequency  spacing  of the  side  bands  originates ,   yes, psk31 , over driven  produce's  IMD  but  wspr  is a  single  phase cont  tone  system 

 

do you  see  this  pattern from  your   SDR ? 

 

Tnx- G,

From: John Langridge

Sent: Wednesday, July 01, 2015 5:37 PM

To: rsgb_lf_group@blacksheep.org

Subject: Re: LF: what causes this on wspr

Two real options:

1) over driven audio, as your picture caption suggests

or

2) the rx site is close to the TX station and is overloading the receiver.  I have a remote Ensemble II LF SDR at a site 1 mile away from my TX and I overload it like this regularly but its not because I'm over-driving my system.  The signal is simply to strong for that distance and the receiver is in an overload condition.

73!

John KB5NJD / WG2XIQ

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From: Graham <g8fzk@g8fzk.fsnet.co.uk>
To: rsgb_lf_group@blacksheep.org
Sent: Wednesday, July 1, 2015 11:24 AM
Subject: LF: what causes this on wspr

what causes this  on wspr

 

This  takes  some  doing  ...... but  how  to  do  it  ?

 

G,