Hi I've always calibrated my phase noise setups to the phase slope of the mixer I'm using. It does involve switching gains, but it's a direct system calibration. Beat note is 360 degrees, so this chunk is x degrees and you got y mv over that chunk. Check the slope on the other side of the beat note to make sure it's the same. Do some math and you have a radian to volt transfer function.
If you are sorting junk box OCXO's it's a pretty good way to do it. The only added steps are an independent measurement of the switched gain / gain flatness and a short circuit input check to estimate the noise floor. Both are an initial setup / one time only sort of thing with most amps. Bob -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths Sent: Tuesday, August 24, 2010 3:25 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Phase noise measurement (was - no subject) Bob Camp wrote: > Hi > < CHOP > .... Being able to calibrate the preamp + sound card frequency response using the thermal noise of a resistor is convenient. This is more difficult to achieve with a bipolar input stage as the amplifier input current noise is significant. Bruce _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.