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Re: GPS reference frequency standard?



I developed a Carrier Phase Tracking Receiver for WWVB several years ago that
satifies my needs as a local frequency reference.  It disciplines a 10 MHz
VCTCXO against WWVB's carrier at 60 kHz.  (The receiver can probably also be
made to work for JJY and MSF on 40 and 60 kHz.)

Within 5 minutes of applying power, the receiver is locked to WWVB, and I'm
1622 miles east of Ft. Collins using an indoor antenna.  Besides providing
outputs at 10 MHz, 1 MHz, 100 kHz, etc., my receiver also provides the current
UTC date/time/UT1 offset on an LCD display, and keeps my PC clock accurate by
sending out a date/time string via a 19.2 kbps serial link.

Operating in concert with a homebrew quadrature phasing receiver and a
frequency counter (using my frequency reference as its timebase), I'm able to
measure the Doppler shift observed on CHU's 3.33 MHz carrier, and estimate the
ionosphere's late evening average rate of ascension (about 8 miles per hour).

Using the same approach, I've measured the carrier frequencies of some local AM
broadcast stations receivable over groundwave paths.  I found two (WOR and WBZ)
to be EXACTLY on frequency (down to 1/1000 Hz) with absolutely NO detectable
drift.  Each turned out to be running IBOC equipment with GPS-disciplined
Rubidium oscillators in their exciters.

Works for me.  :-)


73, de John, KD2BD


Visit John on the Web at:

	http://kd2bd.ham.org/
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