[time-nuts] Looking for Wavecrest Visi
Dr Bruce Griffiths
bruce.griffiths at xtra.co.nz
Sat Apr 7 19:32:16 EDT 2007
Some of the highest resolution techniques for comparing 2 10MHz sources are:
1) Use a Quartzlock A7-MX - resolution 5E-14/tau equivalent to 50 fs at
2) Use the JPL technique: Measure the beat frequency between the 2
oscillators (offset one oscillator by 1Hz using an offset generator if
necessary) and measure the period of the beat frequency. resolution
1E-14/tau equivalent to 10fs at 1 sec. With 100MHz sources the
resolution is 10x higher (1E-15/tau). Most sources (including hydrogen
masers) have greater frequency instability then this. A time interval
counter with better than 100ns resolution will suffice.
To sustain the resolution at long averaging times it is necessary to
regulate the humidity and temperature of the electronics used.
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