K3: Optimizing TEXT DECode for CW

[KM5Q]

The K3 TEXT DEC system works well on CW signals that are above the  
noise level, but to use it for weaker signals and noisy conditions  
requires some understanding and technique. Here's what I learned.

The decoder gets its signal from the same trigger as the CWT indicator  
bar. See for yourself -- When your display is in CWT mode, play with  
the RF gain so the CWT bar goes on and off. The moment it disappears,  
the decoding stops. As soon as the CWT bar flickers with noise, the  
decoder TRIES  to read the on/off signal. If the CWT bar is responding  
to clean code, you will get good text. If it isn't code,  
unfortunately, the decoder tries anyway, and produces junk text.

If the CW signal is audible but is not stronger than the noise, the  
CWT bar will flicker from the noise AND the CW, and the decoder will  
show too much junk. Once you accept that, you can reduce frustration.

To minimize junk text from QRN, hold TEXT DEC, then adjust threshold  
(thr ...) upward until it "squelches" the CWT bar. Now, The text  
decode will work if there is CW signal above the noise.

But now, set the threshold a little lower, slightly too sensitive.  
This will allow for varying conditions. When noise works the CWT bar,  
reduce the RF GAIN until the bar disappears. This is how to fine-tune  
the threshold quickly.

If you get static crashes or other erratic noise triggering the  
decode, don't let  "IISKSK IEN SKSK" distract you.  Watch the CWT bar.  
Let THAT tell you when to watch the text -- when it LOOKS like code  
rather than noise.

Maybe future firmware will improve the decoder so it will ignore  
noise, but for now, this is the best way I have found to use it.

Windy KM5Q
Santa Fe, NM
K3 #764
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[N4LQ-2]

I tuned in a couple of guys on 40m tonight who were going between 50 - 55
WPM. I set the decode to 30-90 but it wouldn't decode much of anything
except a few words now and then. Signals were very strong. No amount of
tweaking the RF gain or bandwidth helped. No biggie though. Mixw couldn't do
it either. My ears did fine. Fast code seems to take a bit of time to sync
up and as soon as the op skips a beat or something, it seems to loose track
of what it's doing.
Steve Ellington
[hidden email]
----- Original Message -----
From: "KM5Q" <[hidden email]>
To: <[hidden email]>
Sent: Friday, May 23, 2008 12:10 AM
Subject: [Elecraft] K3: Optimizing TEXT DECode for CW

> The K3 TEXT DEC system works well on CW signals that are above the
> noise level, but to use it for weaker signals and noisy conditions
> requires some understanding and technique. Here's what I learned.
>
> The decoder gets its signal from the same trigger as the CWT indicator
> bar. See for yourself -- When your display is in CWT mode, play with
> the RF gain so the CWT bar goes on and off. The moment it disappears,
> the decoding stops. As soon as the CWT bar flickers with noise, the
> decoder TRIES  to read the on/off signal. If the CWT bar is responding
> to clean code, you will get good text. If it isn't code,
> unfortunately, the decoder tries anyway, and produces junk text.
>
> If the CW signal is audible but is not stronger than the noise, the
> CWT bar will flicker from the noise AND the CW, and the decoder will
> show too much junk. Once you accept that, you can reduce frustration.
>
> To minimize junk text from QRN, hold TEXT DEC, then adjust threshold
> (thr ...) upward until it "squelches" the CWT bar. Now, The text
> decode will work if there is CW signal above the noise.
>
> But now, set the threshold a little lower, slightly too sensitive.
> This will allow for varying conditions. When noise works the CWT bar,
> reduce the RF GAIN until the bar disappears. This is how to fine-tune
> the threshold quickly.
>
> If you get static crashes or other erratic noise triggering the
> decode, don't let  "IISKSK IEN SKSK" distract you.  Watch the CWT bar.
> Let THAT tell you when to watch the text -- when it LOOKS like code
> rather than noise.
>
> Maybe future firmware will improve the decoder so it will ignore
> noise, but for now, this is the best way I have found to use it.
>
> Windy KM5Q
> Santa Fe, NM
> K3 #764
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

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[dave.wilburn]

Thanks for the info, I will give it a shot.  I have been doing my best
to keep my eyes from straying to that and becoming a crutch.  But I
have found it very handy, once a few letters get past me, or I get in
over my head.  It is looking like my time for WPX this weekend will be
hit or miss, but I will keep this in mind when dealing with those odd
prefixes.


Dave Wilburn
K4DGW
K2/100 - S/N 5982
K3/100 - S/N 766

"For those who fought for it, freedom has a flavor the protected will
never know."


KM5Q wrote:

> The K3 TEXT DEC system works well on CW signals that are above the noise
> level, but to use it for weaker signals and noisy conditions requires
> some understanding and technique. Here's what I learned.
>
> The decoder gets its signal from the same trigger as the CWT indicator
> bar. See for yourself -- When your display is in CWT mode, play with the
> RF gain so the CWT bar goes on and off. The moment it disappears, the
> decoding stops. As soon as the CWT bar flickers with noise, the decoder
> TRIES  to read the on/off signal. If the CWT bar is responding to clean
> code, you will get good text. If it isn't code, unfortunately, the
> decoder tries anyway, and produces junk text.
>
> If the CW signal is audible but is not stronger than the noise, the CWT
> bar will flicker from the noise AND the CW, and the decoder will show
> too much junk. Once you accept that, you can reduce frustration.
>
> To minimize junk text from QRN, hold TEXT DEC, then adjust threshold
> (thr ...) upward until it "squelches" the CWT bar. Now, The text decode
> will work if there is CW signal above the noise.
>
> But now, set the threshold a little lower, slightly too sensitive. This
> will allow for varying conditions. When noise works the CWT bar, reduce
> the RF GAIN until the bar disappears. This is how to fine-tune the
> threshold quickly.
>
> If you get static crashes or other erratic noise triggering the decode,
> don't let  "IISKSK IEN SKSK" distract you.  Watch the CWT bar. Let THAT
> tell you when to watch the text -- when it LOOKS like code rather than
> noise.
>
> Maybe future firmware will improve the decoder so it will ignore noise,
> but for now, this is the best way I have found to use it.
>
> Windy KM5Q
> Santa Fe, NM
> K3 #764
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft 
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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