[CQ-Contest] Tip - Weak Signal Detection

[Tony Field]

From: "Pete Smith" <n4zr at contesting.com>
Subject: Re: [CQ-Contest] Tip - Weak Signal Detection
 >

 > At 10:07 PM 2/25/01 -0600, Dan Weisenburger wrote:
 >  >As the band begins to sound dead, switch to wide filter.
 >
 > Boy, this sure doesn't work for me.  It also doesn't seem to me to make
 > theoretical sense, particularly on CW.  Why would the noise floor drop?

The noise floor does NOT drop - and, of course, the noise power is larger
compared to the original cw signal. However....

There is a curious psycho-acoustical phenomena dealing with noise - a weak
signal that is "almost free of noise" is more difficult to hear than one
surrounded in a reasonable amount of broad band (white/pink etc) noise.  The
noise provides a context that the brain needs to decipher the signal.  Thus,
using the SSB filter in a CW contest may result in the ability to copy
signals that are difficult to copy using a narrow cw filter.  Of course,
this is not a guarantee - it depends upon the quality of signal, noise, and
your personal ear/brain system.

There was an interesting article a few years ago in Scientific American that
describes effect.

tony (ve6yp)


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>From K0HB at qwest.net" <K0HB at qwest.net  Mon Feb 26 04:25:05 2001
From: K0HB at qwest.net" <K0HB at qwest.net (Hans K0HB)
Date: Mon, 26 Feb 2001 04:25:05 -0000
Subject: [CQ-Contest] Field Day CW Exchanges
Message-ID: <01C09FAC.3489A0C0.K0HB at qwest.net>


John Aughey wrote:

 > I'm writing some software that simulates a CW contest similar to
 > the way CyberCW does.  I want to be able to recognize and reply to all
 > different kinds of responses.  I would like to know from all of you want
 > you would typically send for some of the standard exchanges.  I'm
 > looking at only Field Day exchanges right now.

 > Calling out for contacts:

TEST K0HB or
CQ FD K0HB

 > Calling to a CQ:

K0HB

 > Replying to the calling station (if you are the CQer):

THEIRCALLSIGN exchange


 > Replying to the calling station (you are the non CQer):

TU K0HB 1A MN

 > Asking to repeat:

THEIRCALLSIGN AGN?

 > Acknowleging:

TU K0HB FD


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