Ralph, did I miss something or didn’t you use a pair of the Discovery boards?

On Wed, 22 Nov 2017 15:38:33 -0800
Ralph Devoe rgdevoe@gmail.com wrote:

That's true. Such a system is increadibly easy to use.
But you can as well go for something like the redpitaya.
Because its architecture is ment for continuous sampling
you can do all the fancy stuff that Sherman and Jördens
did. And thanks to GnuRadio support, you don't even have
to write python for it, but can just click it together using
the graphical interface. How is that for simplicity? :-)
An I know someone from NIST is actually working on making
a full featured phase noise/stability measurement setup
out of a redpitaya.

Oh.. and what I forgot to mention: I know how difficult it is to
do a proper uncertainty and nooise analysis of least-squares of sines.
I tried it last year and failed. There is lots of math involved that
I haven't mastered yet.

		Attila Kinali

--
You know, the very powerful and the very stupid have one thing in common.
They don't alters their views to fit the facts, they alter the facts to
fit the views, which can be uncomfortable if you happen to be one of the
facts that needs altering.  -- The Doctor

Hi Ralph,

On 11/23/2017 12:38 AM, Ralph Devoe wrote:

There is some tough love here, but learned the hard way many times.
Some of it will take time to grasp and accept, but so far all I've seen
have been constructive criticism.

There exist several works that have used SDR approaches to measure
phase. It is not new and unknown. The Microsemi phase-noise and
stability test-sets is good examples.

This is not to say that there is no value in looking at what can be
achieved.

What you do is just a variant of heterodyne receiver, and essentially a
DMTD using ADCs and phase estimation using least square filtering. It
just takes a few re-drawing stages to show that.

You would need to show how the phase estimation is actually done on that
signal, the given explanation is not very helpful as it sketches the
processing and hands of to some library. This crucial point should be
handled with more care and detail. Using such a least-square fit, I want
to understand how the phase is estimated in such non-linear function.

Also, you should compare to I/Q demod, arctan and a truly linear least
square.

Already the title is interesting, since it is really not Allan Variance
measurement as such but phase measurement, which then can be used to
produce Allan Deviation measures.

Cheers,
Magnus

Hi

One other side to this:

There are a number of papers out there on this basic technique (ADC frequency
measurement). There are a number of commercial products that do ADEV
and other measurements this way. It might be a good idea to at least mention
them. It would be even better to look at the sort of accuracy they achieve.

Bob