[time-nuts] Ultra low phase noise floor measurement system for RF devices.

[Dr Bruce Griffiths]

SAIDJACK at aol.com wrote:
> Hi Bruce,
>  
> got it, thanks.
>  
> But isn't a signal source typically single-ended, and has a 50 Ohm source  
> impedance which creates noise?
>  
> Wouldn't we need a source with 1 Ohm source impedance even if the  
> measurement system is cross-correlated?
>  
> Would a differential source suffice?
>  
> bye,
> Said
>   
Said

No, as long as one can arrange the measurement setup so that the source 
noise is nulled by the interferometer, before the correlator.

You may find this paper of Enrico's of some interest
http://www.femto-st.fr/~rubiola/journal-articles/rubiola2003ell-low-signal-power-interferometer.pdf 
<http://www.femto-st.fr/%7Erubiola/journal-articles/rubiola2003ell-low-signal-power-interferometer.pdf>

Bruce