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Re: technical question



Hi All,
 well based on the emails I have received on the BB and privately,it seems 
that everyone seems to agree that  ....

"A modulation type that varies the carrier frequency by the frequency of 
the input. Example - if the input is 10KHz, the carrier frequency will 
deviate from the center frequency by plus and minus 5 KHz depending on the 
design of the modulator."

is wrong,and....

 "the frequency of the carrier is changed according to differences in the 
signal amplitude..the frequency of the input signal determines the rate of 
change in the carrier frequency"

is the correct answer..

although I had one response that maybe described it better...

The frequency of the carrier changes at a 'rate' determined by the frequency
of the input.  For example, if the FM transmitter is modulated by a 1khz 
tone, then the carrier frequency will vary above and below the center 
frequency at a rate of 1khz.
How 'far' above and below is called 'deviation' and is affected by 
modulation amplitude,maximum modulation frequency and other factors.


      So now if I could just get AMSAT to fix its glossary we would be all 
set...

but when I sent a note saying that the I thought the glossary was wrong and 
maybe they might change it to a better description I was told...

"Take it up with the ARRL - that is where it came from."

I like the the ARRL but I don't consider them to always be the last word on 
technical issues.... looking in my handbooks or on the ARRL website in their 
glossary I wasn't able to find the description that I have issues with...

   Its a shame that when you find something questionable and suggest something 
different that you get told to basically bug off... I would have preferred 
that they would have at least checked with others first to verify the 
answer...

   You all should go take a look at the new glossary, the FM description isn't 
the only one that raised a eyebrow....

http://www.amsat.org/amsat-new/information/glossary.php


73 all
Kevin
WA6FWF
#19623
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