[time-nuts] GPS noise reduction

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sun Apr 6 17:24:41 EDT 2008

John Ackermann N8UR wrote:
> That also leads to a thought I've had -- if you have a pair of roughly
> comparable oscillators at say 5 MHz, what about combining their outputs
> in a mixer and using the 10 MHz sum output which (apart from noise added
> by the mixer) ought to be sqrt-2 better than either unit alone?
> John
> ----

Lowest mixer noise is achieved when the difference frequency is 
reflected back into the mixer whilst terminating the sum frequency in a 
matched load.

You can also use several mixers and combine their outputs to reduce the 
effective mixer noise.


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