Re: [IRCA] Microscan 1030 kHz

["Albert Lehr" <aelehr@xxxxxxxxxxxxxxxx>]

----- Original Message ----- 
From: "Brandon Jordan" <bjordan@xxxxxxxx>
To: <aelehr@xxxxxxxxxxxxxxxx>
Sent: Friday, August 13, 2004 4:46 AM
Subject: Re: [IRCA] Microscan 1030 kHz

> Hi Albert--
> 
> I am extremely curious about your frequency measurement system. Could you
> please provide some brief details on the setup?
> 
> 73,
> Brandon Jordan
> Memphis, TN

Brandon,
I recall that you asked about my PFM system about two years ago
on the NRC list, and I replied to that list.
Since a few others are also curious, here is a brief explanation of my 
frequency measurement system.
It will work only with a single conversion receiver such as my Allied
A-2515 and requires outputs from the local oscillator and the final
455 kHz IF stage.  Other requirements are an external synchronous 
detector, a frequency counter and an accurate and stable timebase 
generator.
All of the circuitry needed to produce a measureable signal for the
counter is located in the sync detector unit.  Quite a bit of construction 
work is involved.
A 455 kHz Voltage Controlled Oscillator in a phase-locked loop 
locks on to the carrier in the IF channel. The VCO output and the 
local oscillator output are converted to pulses and both are sent to a 
Digital Timing and Gating circuit.  For every pulse that is present in the 
VCO branch, one pulse is removed from the local oscillator branch.  
The resulting output of the DTG circuit is a pulse train with missing 
pulses scattered throughout it.  It is somewhat like walking alongside 
a picket fence and periodically removing a picket. A frequency counter 
connected to the output displays the exact frequency of the station you 
are tuned to. I am using a homebrew external time base generator with 
my frequency counter.  It is phase-locked to WWVB on 60 kHz.

A more detailed description appeared in the IRCA Technical Column 
in the hard copy DX Monitor for January 2, 1999.

Albert Lehr - Livermore, CA
_______________________________________________
IRCA mailing list
IRCA@xxxxxxxxxxxxxxxx
http://dallas.hard-core-dx.com/mailman/listinfo/irca

Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers

For more information: http://www.ircaonline.org

To Post a message: irca@xxxxxxxxxxxxxxxx