RTTY
[Top] [All Lists]

Re: [RTTY] Problems with AFSK ...

To: rtty@contesting.com
Subject: Re: [RTTY] Problems with AFSK ...
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Tue, 27 May 2014 10:05:22 -0400
List-post: <rtty@contesting.com">mailto:rtty@contesting.com>

I have also seen wsjt decode two copies from the same station in
different parts of the screen, overdrive on transmit must have been
the problem...

Decoding WSJT at two places on the waterfall is entirely different than
the problem what was shown here.  In those cases the transmitter is
actually transmitting two signals due to typically due to mixing with
a spurious signal (typically a harmonic of the 50 or 60 Hz power supply
ripple or a spur on the carrier oscillator) somewhere in the RF chain.

In this case all of the harmonic signals were entirely uncopyable
because the shift was also increased by the 'harmonic factor'.  The
only thing signals of this type do is trash the band for everyone
else.

73,

   ... Joe, W4TV


On 2014-05-27 9:30 AM, steve wrote:
Joe, thank you for also putting the comments in the wsjt group, too.
I have often seen "ghost" patterns in my wsjt decode and thought it
might be a DSP "defect".
I have also seen wsjt decode two copies from the same station in
different parts of the screen, overdrive on transmit must have been the
problem...
I had a difficult time going from zero ALC on my TenTec to "4-5 bars" on
my KX3, but I don't "think"  I am overdriving (I hope)...

73, steve WB3LGC

On 05/26/2014 08:29 PM, Joe Subich, W4TV wrote:

Lest anyone doubt the problems with AFSK and users who follow the
"all knobs to the right" doctrine take a look at the spectrum of
one lid on WSJT : http://www.w4tv.com/HI8XXX.jpg.

...

73,

   ... Joe, W4TV

_______________________________________________
RTTY mailing list
RTTY@contesting.com
http://lists.contesting.com/mailman/listinfo/rtty


_______________________________________________
RTTY mailing list
RTTY@contesting.com
http://lists.contesting.com/mailman/listinfo/rtty

_______________________________________________
RTTY mailing list
RTTY@contesting.com
http://lists.contesting.com/mailman/listinfo/rtty

<Prev in Thread] Current Thread [Next in Thread>