R: [Linrad] Re: Frequency scale in Linrad

["libero.it; ik7ezn@xxxxxxxxxxxxxxxx>]

Hello Leif.
I did as you suggested and I got what I wanted.
Now the scales 
coincide with the frequency of Linrad and frequency in MAP65.
Thank you for 
your usual availability.

73 Ermanno / ik7ezn

>----Messaggio originale----

>Da: leif@xxxxxxxxxx
>Data: 14/11/2009 21.13
>A: <linrad@xxxxxxxxxxxxxxxx>

>Ogg: [Linrad] Re: Frequency scale in Linrad
>
>
>Hello Ermanno,
>
>> Use 
Linrad as front-end for MAP65 and WSJT.
>> To view an jt65 
>> signal, on the 
waterfall of linrad (SSB), shift the BFO to -1270.5 and filter 
>> to about 2.4 
kHz.
>> The frequency in Linrad corresponds exactly to the specified 
>> 
frequency of MAP65 (+/- Doppler).
>> The audio output from Linrad, which uses 
as 
>> input for WSJT is perfectly focused (DF = 0) on the desired signal.
>> 

>> The 
>> problem is that the scales of frequency of all windows of Linrad 
indicate a 
>> different frequency, that is without compensation of the BFO.
>> 
It is difficult 
>> to click on the signal desired in high resolution spectrum, 
especially when 
>> there are many JT65 signals in a few kHz.
>> 
>> How to get 
the right indication on 
>> the scales-frequency of Linrad  ?
>The frequency 
readout gives the frequency of the carrier. In SSB mode
>that is the frequency 
of the BFO. In CW mode the carrier is assumed to be
>placed at the center of 
the baseband filter. If you use AFC it will
>be forced to the center if locking 
is sucessful.
>
>You should run in CW mode. Then a carrier (or a JT65 sync 
tone) that
>is placed at the baseband center would produce a frequency readout

>that is in agreement with the frequency scale in all the graphs 

>independently of the BFO setting. By placing the BFO 1270.5 Hz below
>the 
passband center you can make the frequency of a signal at the
>passband center 
appear at 1270.5 Hz in the output. In this way the
>true frequency of the sync 
tone which would be shown in the frequency
>readout as well as on all scales 
will differ from the MAP65 readout
>by 1270.5 Hz. That is because Joe decided 
it is easier that way for 
>people who use an ordinary radio. (I am NOT in 
favour of that, but now
>it is the established "standard" for JT65. )
>
>To 
make all the scales as well as the frequency readout show the true
>frequency 
with a 1270.5 Hz shift you should make a users_hwaredriver.c
>that sets a 
frequency that differs from the hardware frequency by 1270.5 Hz.
>
>If you use 
the WSE units, edit users.c and make it contain your own version 
>of wse_sdrxx.
c which would differ from the standard version by having
>int 
rx2500_fqcorr=1270.5; (Or perhaps minus...)
>
>That way scales and readout 
would no longer show the frequency, they
>would all show the true frequency 
plus (or minus) 1270.5 Hz.
>
>In case you are not satisfied by having Linrad 
and MAP65 showing the
>same frequency but want the frequency of both to agree 
with the true
>frequency you would have to add a frequency correction to the 
1270.5 Hz
>and add the same correction to the frequency that you feed into 
MAP65.
>
>73
>
>Leif / SM5BSZ
>
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