I may not have knowledge, but i have a theory. People use different bandwidth
filters for various reasons, some for what they have and some for hearing more
after a CQ and other reasons. If you are listening to a signal at 400 Hertz
you also hear QRM that is in your bandpass. If you are using a 200 Hertz
filter you hear from 300 to 500 at the rating of your skirt, but you also hear
QRM from the bottom of your actjual bandpass to the top of your actual bandpass
depending on the actual signal strength. If you are using a wider bandpass it
depends on the actual bandpass and the strength of the QRM, so you hear more at
higher frequencies than lower. Of course how much you hear lower depends on
the low cutoff of your audio which is presumably above zero and below about 3
khz. If you are an audiophyle maybe higher. Noise frequency goes up to the
cutoff of your ears or audio. That is my theory and I am sticking to it!
Willis 'Cookie' Cooke,TDXS Contest Chairman K5EWJ & Trustee N5BPS
From: Rick Tavan N6XI <rta...@gmail.com>
To: Sverre Holm (LA3ZA) <la...@nrrl.no>
Cc: Elecraft Reflector <elecraft@mailman.qth.net>
Sent: Monday, March 2, 2015 12:25 AM
Subject: Re: [Elecraft] CW listening pitch
Yes, I've noticed this. I have no real knowledge of why low tones seem to
make for better copy in QRM but I have guessed that it has to do with the
relative difference in interfering tone for a given offset from the desired
signal. If you listen to 1000 Hz (which many ops do) and the interfering
signal is 100 Hz away, the difference is only 10%. But if you listen to 400
Hz, the difference is 25%. So the filter in your brain may be more
effective distinguishing 400 from 500 Hz than it is in distinguishing 1000
from 1100 Hz. Just a guess.
73,
/Rick N6XI
On Sun, Mar 1, 2015 at 7:33 PM, Sverre Holm (LA3ZA) <la...@nrrl.no> wrote:
> There is evidence that it is advantageous with a low tone for the pitch
> (asuming normal hearing). Some studies give evidence for an improvement in
> recognition rate as the pitch is lowered and it more or less seems to level
> off at 500 Hz, except for the lowest SNRs where recognition even improves
> at
> a pitch of 250 Hz.
>
> Some of the research is summarized here (look for paper 2):
> http://la3za.blogspot.no/2013/10/studies-on-morse-code-recognition.html
>
>
>
>
>
>
> -----
> Sverre, LA3ZA
>
> K2 #2198, K3 #3391,
> LA3ZA Blog: http://la3za.blogspot.com,
> LA3ZA Unofficial Guide to K2 modifications:
> http://la3za.blogspot.com/p/la3za-unofficial-guide-to-elecraft-k2.html
> --
> View this message in context:
> http://elecraft.365791.n2.nabble.com/CW-listening-pitch-tp7599535p7599630.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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--
Rick Tavan N6XI
Truckee, CA
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