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

[Bob kb8tq]

Hi

If you dig into the various books on phase noise, they do go into other 
ways to measure it. The bottom line is that things like frequency discriminators
are quite noisy (floor wise) compared to a single mixer. 

Bob

> On Jul 10, 2022, at 10:26 AM, ed breya via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> 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
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