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Re: LF: 500 kHz JT4A

from [Andy Talbot] [Permanent Link][Original]
To: [email protected]
Subject: Re: LF: 500 kHz JT4A
From: Andy Talbot <[email protected]>
Date: Fri, 22 Jan 2010 21:49:54 +0000
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That sync figure  not 'poor'.  The mode will decode with values as low as 3 or 4.
 Just not as good as it could be in pure noise at that S/N.
 
Pulse type QRM interferes with the decoding process more than poor S/N does.
2010/1/22 Rik Strobbe <[email protected]>
Andy,

thanks.
I just decoded Gary : "CQ G4WGT IO83", sync = 11 , dB = -2.
Not sure wether QRM is an issue, I see 2 bright traces against a black background.
What else could cause the poor sync ?

73, Rik  ON7YD - OR7T


Quoting Andy Talbot <[email protected]>:

See annotations below

Andy
www.g4jnt.com<http://www.g4jnt.com>


2010/1/22 Rik Strobbe  <[email protected]<mailto:[email protected]>>

As said I haven't read any instructions / manual but maybe the  figures WSJT7 spits out on the readable copies of Jim may give a clue:
Sync = 9            Not brilliant for -2dB S/N   but blame the bad QRM
dB = -2               Very good signal (This is the S/N normalised to 2.5kHz)
DT = 0.0             Timing spot-on, no error between clocks at both ends
DF = -107           -107Hz tuning error
W = 33                Not sure -

73, Rik  ON7YD - OR7T
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