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Re: Wideband Noise on 500 kHz [was RE: LF: WD2XSH/17 on WSPR]

To: <[email protected]>
Subject: Re: Wideband Noise on 500 kHz [was RE: LF: WD2XSH/17 on WSPR]
From: "Graham" <[email protected]>
Date: Sun, 7 Nov 2010 13:26:23 -0000
Importance: Normal
In-reply-to: <[email protected]>
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Ok Dave,
 
So much  for the  skip  theory , unless  its  leaking out of the  ground , may be the  channel tunnel  is  acting as a  large  coax cable  
 
if you  have a high  noise level to  start with  , +10  is not good  news , may be the  original  wspr  slot  at the  top  of the  band is still
the  better  option , pity the  tx time is  so long , its not really matched to  LF , if you  only  capture regularly   25% of the  sync
then  sending the  other 75% is questionable ?
 
G..

Sent: Sunday, November 07, 2010 8:25 AM
Subject: Wideband Noise on 500 kHz [was RE: LF: WD2XSH/17 on WSPR]

Graham, LF,
 
I checked the wideband noise at midnight last night with my SPM-30 (3 kHz bandwidth). It was clearly audible, and had the sort of buzz-saw rumble that one finds on HF occasionally. The levels were:-
496.0 kHz    - 81 dBm
500.0 kHz    - 73dBm
504.0 kHz    - 83 dBm
So it's about 8 to 10 dB above my local background noise level :-(
 
No WSPR stations copied last night on 501 kHz.
 
73, Dave G3WCB IO91RM nr Windsor, S.E. England
-----Original Message-----
From: [email protected] [mailto:[email protected]]On Behalf Of Graham
Sent: 06 November 2010 13:22
To: [email protected]
Subject: Re: LF: WD2XSH/17 on WSPR

Dave,
 
I think the  sharp cut-off   is the only elegant  part of it ? , using  spec-lab , I can  see a  drop  of 10  to 15 dB over 502 KHz .. suppose its a good  place to  try data modes out .. interestingly , wspr is not  producing any  false  decodes and the  WD signal  decoded  twice , which I think is  actually  times 4 decodes , round  2400 z , but may be the  s/n  distorted by the  noise floor increase ? my 100 watts  crossed once , but  gave a  better s/n
 
There  may be a possibility , that you are  inside the  skip  range and out of the  ground  75/100  mile  range ..?
 
I see  a  couple of S points on the  meter as I tune over the  noise ..marvellous .. and the  pulse modulated  Christmas  lights are  yet to  come   ...... hum-bug
 
73-G.

Sent: Saturday, November 06, 2010 12:43 PM
Subject: RE: LF: WD2XSH/17 on WSPR

Hi, Graham.
 
It's probably contributing to the overall high level of crud at this QTH, but I'm not aware of exactly how much it is adding.
 
I'll do some tests over the week-end and try to measure the contribution. From what I've seen on the various grabbers, it seems to have a fairly well-defined H F cut-off, so it should be easy to identify where the wideband datalink noise ends and the usual hash continues.
 
Cheers
 
Dave
-----Original Message-----
From: [email protected] [mailto:[email protected]]On Behalf Of Graham
Sent: 06 November 2010 11:07
To: [email protected]
Subject: Re: LF: WD2XSH/17 on WSPR

Dave,
 
Do you  see  the wide band noise  at  + 10 to  +15 dB over the  background  noise ?
 
G..
 

Sent: Saturday, November 06, 2010 8:23 AM
Subject: LF: WD2XSH/17 on WSPR

I snagged WD2XSH/17 last night on WSPR. This is pretty good going for this QTH, as I have a very high local noise level on 500 kHz.
2010-11-06 04:06  WD2XSH/17  0.501091  -27  0  FN42pb  +30  1.000  G3WCB  IO91rm  5233  3252  
 
73, Dave G3WCB IO91RM nr Windsor, S.E.England






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