[Lowfer] Sampling Rate and Frequency Calibration

[Garry Hess]

John, I like to use a pitch of 400 Hz so I've programmed the offset as 
73921 (Hz). With an SDR-IQ center frequency of 73921 Hz, USB that places 
74321 Hz in the center of the ARGO waterfall, which is near where Bob, 
WG2XRS/4 is sending tonight. It's centered of course because I 
left-click the frequency scale up or down as needed to make it so. When 
I listen with a 1000 Hz pitch I must move the frequency slider up quite 
a bit so that pitch is centered in the waterfall. It's easiest to do 
that using 0 Hz as the offset, then after 1000 is showing in the middle 
of the waterfall I add the tuning value, adjusted by tuning error, if 
any. I can specify the 66.666... MHz SDR-IQ clock to within 0.5 Hz so 
when I'm receiving that way, as opposed to using my alternate IC706MkIIG 
receiver, there isn't any significant tuning error.
-- 
73, Garry, K3SIW, EN52ta, Elgin, IL