2009/8/17 Bruce Griffiths <[email protected]>: > [email protected] wrote: >> Please, how do time-nuts measure phase noise? What may be a minimal setup >> whit recording capability? >> Thanks, >> Antonio I8IOV >> >> >> > A minimal setup for the classical method requires 2 frequency sources at > the same frequency one of which can be phase locked in quadrature (with > low loop bandwidth) with the other. > The output spectrum of the phase detector outside the PLL loop bandwidth > is then proportional to the relative phase noise spectrum of the 2 > sources and is measured using a spectrum analyser. > A double balanced diode mixer is used as a phase detector (most other > types of phase detectors are far too noisy). > A sound card with a suitable low noise preamp can be used as an FFT > based spectrum analyser in the ~10Hz to ~20kHz range, the actual > frequency limits depend on the sound card and its sampling rate.
So how do you discriminate against the phase noise of the source you are using as a standard frequency? Do you have to use a known low phase noise standard to mix with your unknown source? Steve > > > Bruce > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Steve Rooke - ZL3TUV & G8KVD A man with one clock knows what time it is; A man with two clocks is never quite sure. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
