[Lowfer] Frequency Calibration

Wed, 6 Nov 2002 15:13:22 -0600

John: I can see BRO most of the time, and Lyle all of the time, not trying
to get a perfect calibration, I'm just trying to prevent myself from looking
for signals on the wrong frequency like I have been doing for the past three
nights. I have still yet to see a skywave signal on LF. I will calibrate
Argo when I get home and run some more captures.
	What do you use for an antenna on rx and do you run a pre-amp??

-----Original Message-----
From: John Andrews [mailto:[email protected]] 
Sent: November 6, 2002 2:37 PM
To: [email protected]
Subject: Re: [Lowfer] Frequency Calibration

Vern,

> John: just looked at a capture of WWVB and it shows 800.5 hz centre 
> frequency with sidebands

OK - at least a signal would be visible on your Argo screen, even at the
narrowest resolution (120sec gives about 2 Hz top to bottom).  Your goal
would be to get WWVB or some other right-on-frequency signal to show at
800.00.

It's really a 2-step process as that article of mine indicates. First you
need to fudge for any error in sound card sampling rate, and you'll need a
precisely known audio frequency for that. As the article mentions, you can
use Loran-C. For your area, if you put your radio in AM mode, and tune to
100 kHz, you should get fairly bright Argo lines at 802.68 Hz and 791.53 Hz.
I'd suggest narrowing the display to the 30 second screen, with that line
more or less centered. If Argo shows something different, go into Argo's
setup, select calibration, and use the measured and displayed frequency
boxes as described in the article.

Unless you are trying to calibrate the receiver from DC to light, you may be
able to fudge the next step without opening the receiver. Go back to CW
mode, and tune in some frequency you can trust. As Lyle suggests, BRO is
dead on, as is WWVB. The only advantage to BRO is that you can guarantee the
calibration within the "lowfer" band. Let's say that you use BRO. Set the
receiver for 182.200, and if the line isn't right on 800 Hz, then go into
setup and calibration again, and enter an offset (+ or -) that will put BRO
right on 800.00.

John Andrews

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