Relative frequency measurement using mixer, what is the maximum usable IF frequency?

[Terminator3]

Currently prescaler ICs whith input of 10GHz and higher are relatively expensive.
I am considering using reference oscillator with mixer to extend range of frequency measurement using cheaper prescalers.

Configuration:
reference oscillator with known frequency (10GHz)
diode or FET mixer
prescaler IC with input up to 3GHz

Could this configuration be used to measure 7GHz to 9.9GHz and 10.1GHz to 13GHz? It is known if frequency is below or above reference.
For example: reference LO=10GHz, RF=13GHz, IF=3GHz?
My main concern is about mixer performance. What would be output level at IF=3GHz? What topology is best choice for this case?
1) Single diode mixer - good sensitive, low isolation
2) Single balanced diode mixer - added isolation
3) Double balanced - doubt it needed here ?

Could it be used to measure bigger differences, for example:
reference LO=10GHz, RF=23GHz, IF=13GHz.
Prescaler IC up to 13GHz. LO must be filtered very well before prescaler. What about IF output level. Is it even exists? I know IF of few KHz and even MHz is pretty common, how about larger differences, what are limitations?

Thank you!

 

[betwixt]

Yes, that method will work, in fact it's how many PLL systems operate. Using a mixer to drop the input frequency retains any deviation of frequency while pre-scaling it divides the deviation by the prescaler ratio. Your problem will be choice of LO frequency in order to prevent images being measured as well. Filters will be required to eliminate the image product.

Brian.