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Mon Nov 17 11:01:15 2008
Calibrating the Frequency Standard of the Marconi
I locked the
SRS Rubidium Frequency Standard FS275
to the the 1pps from the GPS. The specs from the manual provide a frequency accuracy of 5x10^-11, that is 5x10-4 @ 10 MHz, since this is the reference signal frequency we're are going to use.
The Marconi internal frequency standard is provided by a TCXO oscillator. The instrument can be set in either one of these ways: 1) Indirect Synchronization, by which the internal TCXO is phase-locked to the external frequency standard (i.e. the SRS FS275 in our case) 2) Direct Sync, in which the internal TCXO is bypassed and the frequency standard is the external one.
I checked the specs of both frequency standards and found:
: 5x10^-11 -> 5x10^-10 Hz @ 10 MHz
: here what the data sheet says is that "the temperature coefficient is 7 in 10^7 in the temperature range between 0 and 55 C" and so should be also the frequency accuracy.
The SRS FS275 seems more accurate than the TCXO therefore I'm going to set the Marconi on the direct external mode.