[EMAIL PROTECTED] wrote: > > In a message dated 3/30/2007 16:02:15 Pacific Daylight Time, > [EMAIL PROTECTED] writes: > > It does in fact measure below the thermal noise floor. > This is not too difficult as it uses a crosscorrelation technique. > > Bruce > > > > Hi Bruce, > > interesting how microphonic effects would affect the results. > > I see my instrumentation jumping by several 1E-12 units everytime I walk > into the lab since my benches are not shock insulated. > > At -200dBc (we have to think about that number for a while!!) - that's > counting single electrons every couple of seconds I would think... > > bye, > Said > > > > ************************************** See what's free at http://www.aol.com. > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > Said
Actually I should have said -200dBc/Hz. With a +13dBm carrier this corresponds to a noise voltage of 100pV/rtHz across a 50 ohm resistor or a noise current of 2pA/rtHz flowing through it. Even with a 1Hz noise bandwidth thats an rms fluctuation of about 12,500,000 electrons. You have to get down to noise currents of around 1attoAmpere/rtHz before you start "counting" individual electrons. Yes vibration isolation, is essential which is why their prototype was built on a vibration isolated optical table. Bruce _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
