[DSP-10] [Fwd: Re: [Moon-net] ICOM 275 A] pretty interesting....

[Hermann (Pit) DC9UP]

-------- Original-Nachricht --------
Betreff: 	Re: [Moon-net] ICOM 275 A
Datum: 	Thu, 04 Dec 2008 11:37:15 -0500
Von: 	Joe Taylor <joe at Princeton.EDU>
An: 	Serge Szpilfogel <ve1kg at eastlink.ca>, moon-net at list-serv.davidv.net
Referenzen: 	<1D9E24ADB8A447659B5BC1C7A816D2BF at LAPTOP>



Hi Serge,

Probably you have already figured this out, but
in case not ...

VE1KG wrote:
> I was on JT for the first time in November during the 
> contest. Most people i worked said i was 1 KHZ  up of 
> the frequency annonced. Got a freq counter which shows 
> i am actually 2 khz up.  When on cw transmitting on 
> 144127khz god forbid it shows that iam actually on 
> 127.750 khz. Which is correct since this 25 year old 
> transceiver the carrier is moved 750 hz up when on CW. 
> Now why is it that when i am transmitting in the USB 
> position for JT my freq counter shows 2 khz up from 
> the freq annonced?? I have not spoken about the doppler 
> since apparently JT takes care of it. or does it?

By convention, everybody specifies their JT65 frequency as 
that of the suppressed carrier.  Transmitted audio tone 
frequencies start at 1270.46 Hz (the "sync tone") and go up 
from there.  So, when somebody says they are on 144.127 MHz 
using JT65, it means their sync tone should be on 144.128270.

The WSJT program tells you what the Doppler shift will be, 
but does not do anything to "take care of it".  On 2m, of 
course, you can pretty much ignore Doppler shifts since they 
are around +/-300 Hz, or less -- comparable to the frequency 
readout uncertainties of many transceivers or 
transceiver/transverter combinations.

	-- 73, Joe, K1JT

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