Hi Neil, thanks for responding. I'm working at 25 MHz. I have five
different clocks ranging from from low cost clock chips to expensive
stable sources. The project started with looking for an easy benchtop
way to compare their stability without an expensive analyzer. More
specifically, when we realized that the mid range spectrum analyzers of
which we have several couldn't measure phase noise low enough to
distinguish any of the clocks. It's not an issue of finding good clocks
as we have that but comparing stability among them.
Best,
Karl
On 8/20/2024 2:48 PM, salmon.na via casper@lists.berkeley.edu wrote:
Hi Karl,
Cant you just use specifications on phase stability of standard sources of
varying degrees of stability which would be a function of price? What radio
frequency are you working at. Tube sources tend to have good phase stability.
There might be some old but goodies on ebay. There's also an HP user group
https://groups.io/g/HP-Agilent-Keysight-equipment where you might find a few
low cost sources from those I keep the old kit working. Also a good source of
technical data on radar technology and knowhow.
Cheers,
Neil
-----Original Message-----
From: casper@lists.berkeley.edu <casper@lists.berkeley.edu> On Behalf Of Karl
Warnick
Sent: 20 August 2024 21:38
To: casper@lists.berkeley.edu
Subject: [casper] Low cost phase noise analysis
Hi all,
I've spent some time this summer as part of a radar project digging into
calculating phase noise for highly stable tones. I have implemented what I
think is a decent algorithm. My next steps are to look for test data sets and
tips for the hardware.
Do you have a file of samples of a stable tone? If anyone has a test data set
consisting of samples of a pure tone that they would like to share as a test
data set, I'd like to apply my codes to that and check the phase noise. Both
the tone generator and the ADC sample clock should be phase stable to the order
of a Keysight signal generator, or ideally better. The data set length should
be a reasonable fraction of a second for ~1 Hz phase noise resolution. The
frequency of the tone and the sample rate are fairly arbitrary as I'm mainly
looking to benchmark the algorithm.
How cheaply can stable samples be acquired? I'm looking for low cost hardware
(a few $100s up to a few $k) that is stable enough to measure phase noise
comparable to a Keysight source or better. Phase noise can be measured with an
expensive phase noise analyzer, but I believe it should be possible to do this
with a low cost digitizer with a suitably stable sample clock. The sample clock
could (or perhaps must) be external. The sample rate should be around 80-100
Msps or higher and the platform should be able to store a burst of samples of
length on the order of 1 sec. We have done this using a ZCU 216 and it seems to
work, but that isn't really a low cost board. I've looked into Picoscope
products, which might be ideal, but their support people don't know anything
about the phase noise properties of their samplers.
Thanks in advance to anyone whose interest is piqued enough to respond.
Best,
Karl
--
Karl F. Warnick
Parkinson Engineering Research Professor Department of Electrical and Computer
Engineering Brigham Young University
450 Engineering Building
Provo, UT 84602
(801) 422-1732
--
Karl F. Warnick
Parkinson Engineering Research Professor
Department of Electrical and Computer Engineering
Brigham Young University
450 Engineering Building
Provo, UT 84602
(801) 422-1732
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