[Lowfer] ARGO calibration

[John Andrews]

Steve,

> How is ARGO calibrated when it shows the exact frequency, for instance 
> 137777?  I have my receiver set to 137777, cw mode, the BFO is at +800 
> which should be the center of the filter.

In that case, if there was a carrier on 137.777 kHz exactly, you would 
get an approximate 800 Hz tone from the receiver into the sound card. 
There are then three things you can set with Argo's Setup/Calibration 
screen:

1. The Measured/Displayed Frequency windows can be used to compensate 
for your sound card's actual sampling rate. Note that this has nothing 
to do with your receiver, just your sound card.

2. The Offset window can be used to compensate for any error in the 800 
Hz coming from your receiver. That would complete the calibration 
necessary to get an accurate 800.00 Hz reading.

3. With the above done, you make a note of that value in the Offset 
window. Let's say it came out as -0.11 Hz for that 800 Hz signal. If you 
wanted the screen to say "777" on the right instead of 800, then you 
should put 800 - 777 -0.11 = 22.89 Hz in the Offset window.

If you want some tips on doing steps 1 and 2, go to:
http://www.lwca.org/library/articles/w1tag/R75cal.htm

John Andrews, W1TAG