[time-nuts] External clock for Analog to Digital Converter inGPS Rx front-end
Dr Bruce Griffiths
bruce.griffiths at xtra.co.nz
Sat Mar 3 16:29:48 EST 2007
Arnold Tibus wrote:
> HP was using in their 500MHz counter 5345A a noise generator
> (zener diode with amplifier on PC board 'A8 PLL Multiplier Noise Generator
> board') to modulate via a varactor and a tank circuit the 10 MHz
> reference frequency coming from the ocxo 10811A.
> "4-126, As the erratic changes in noise affect CR12's capacitance, the
> phase of the 10 MHz signal shifts rapidly. The result ia a 500 MHz time base
> signal that is phase modulated so rapidly and erratically that it cannot be
> harmonically related to any input signal."
> Intersting technique, easy to follow.
> Is that what was searched, would such a circuit help?
> The manual is freely available via the net as .pdf.
> Perhaps that board, cannibalized from an old counter, could be used...
> I think it is necessary for TIC to get statistically correct intermediate
> Arnold, DK2WT
Circuit is fine for the application it was designed for.
However for measurement purposes accurately calibrating the phase noise
spectrum it generates poses some interesting challenges.
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