[Elecraft] On zero beating

[Steve Lawrence]

Tim,
I too have found this difficult to hear with a discontinuous CW signal. 
The "beat" is produced by the difference in the two audio frequencies: the 
spot tone and the apparent tone of the CW signal.  The beat frequency goes 
down as the differences are minimized further, until the beat is zero -- 
indicating perfect match in frequency.  The ear hears a subtle 
Wah...wah...wah...wah which is the beat note indicating the frequencies 
are not quite matched.  A slight change in the tuning dial, increases or 
decreases  the period of the beat note or the separation of the 
wah.......wah......wah......  The desire is to decrease the beat resulting 
in matched frequencies.

This is easy for me to hear when tuning my guitar, and I suspect a violin 
to be much the same.  Here the tones are long and continuous.  But the 
key, as you well point out, is two continuous tones -- not the case in 
spotting a CW signal.  So, like you, I struggle on the non-continuous 
signal.

Perhaps the "ultimate" spotting tool would be to measure the audio 
frequency of a received CW signal and display it -- perhaps at the touch 
of a button.  Knowing your sidetone is set to, say 700Hz, you could then 
adjust the dial frequency so the received CW signal is also at 700 Hz. 
Since the K2 has a frequency counter logic, perhaps this feature could be 
implemented?

Steve
aa8af








cyr999@extremezone.com
Sent by: elecraft-admin@mailman.qth.net
01/17/2002 03:04 PM

 
        To:     Elecraft Reflector <elecraft@mailman.qth.net>
        cc: 
        Subject:        [Elecraft] On zero beating


Hi folks - 

Although it may be clear as a bell to most people, I thought I would share 
my 
experinces as a beginner with zero beating. It may be of interest to 
newcomers 
in HAM.

Every text I've read seems to define zero beat by referring to the word 
"beat". 
I never HEARD any "beat". What the heck was everyone talking about! I 
never new 
what that "beat" was and finally got too embarassed to ask people anymore 
about 
it.

In the mean time I would tune in on a signal by simply using SPOT and 
matching 
the tone by ear. Since I play the violin, this is very easy for me. On the 
other 
hand, my Code Buddy from FISTS finds that type of thing almost impossible.
The other way I tune is simply to get the signal as loud as I can in the 
narrowest filter setting. With my K1 and K2 that seems to always be just 
about 
dead on.

For you fellow beginners, I was FINALLY enlightened when installing the AF 

filter the other nite. The manual said to zero beat the CONTINUOUS tone at 

7000.00. MAGICALLY WHEN THERE IS A CONTINUOUS TONE ZERO THE DEFINITION OF 
BEAT 
BECOMES TOTALLY OBVIOUS. As soon as you are dead on the two tones sound as 
if 
they are one tone which has a rhythmic rise and fall of the tone. This 
rise of 
the tone is the beat. When you listen to code being sent, you do not have 
a 
CONTINUOUS wave - so you seldom have the signal coming in long enough to 
hear 
this illusive beat!!!! Key word here: continuous :-)

I guess what I am trying to share is what the word BEAT really refers to 
if you 
were confused like me. Also, once I heard what the beat was on the 
contiuous 
wave, it helped me with matching the SPOT even more - you may not hear the 
beat 
per se when receiving code, but you can hear when it's getting right in 
the 
groove. Perhaps listening to really fast ops sends such a rapid signal 
that you 
hear even more of a beat.

Anyway, I found this simple thing to be a true revelation. If it's 
confused you 
- go down to 7000 without the antenna etc etc and you will be able to 
learn the 
true basis of the word BEAT. 

Sorry to bore you experienced folks with this simplicity!! If I've said 
anything 
that needs correction or the voice of experience - please jump in so I 
don't 
mislead anyone!

73/KB7OEX Tim Logan