[time-nuts] What about the frequency discrimination method? (offshoot from DIY PN analyzer)

[ed breya]

Hi Magnus,

I know what you mean about not needing a quadrature splitter - if you 
have a very wide phase or delay tuning range - but I'm picturing getting 
most of the way to quadrature with a fixed structure for a given 
frequency, and only fine-tuning the phase over a narrow range, in order 
to minimize the PLL's overall noise contribution. This should also keep 
it monotonic - too wide a range may let it get stuck on the humps.

For amplitude calibration, I'm picturing rearranging the splitter ports 
or guts somehow (as simply as possible) to present the DUT signal to the 
mixer at 0 or 180 degrees, which should give a maximum DC out.

BTW I had never heard of the Tayloe detector, but it appears to be the 
method (4x f multiplier then digital quadrature divide) used in lock-in 
analyzers, and I have used the same in a number of projects.


Azelio wrote:
"How can you measure something, any type of measure, not only PN,
without a reference? Voltmeters need voltage references, "timemeters"
(and frequency meters) need time references."

Azelio, this is a well known technique - I haven't described anything 
new, just a particular implementation I've been pondering.

Ed