Re: LF: 500 kHz JT4A

[Andy Talbot <andy.g4jnt@googlemail.com>]

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.

Andy
www.g4jnt.com

2010/1/22 Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>

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 <andy.g4jnt@googlemail.com>:

See annotations below

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


2010/1/22 Rik Strobbe  <Rik.Strobbe@fys.kuleuven.be<mailto:Rik.Strobbe@fys.kuleuven.be>>

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