Another great post from Bob (as usual). Bob's advice
is exactly correct. Unfortunately, the
HP 11848 phase noise test set (part of the HP 3048
PN measurement system) is poorly designed, and does
not break out the low gain non clipped signal.
I modified mine to bring out this signal and it
was
Bob kb8tq writes:
> Could be. They also mention a 25 MHz clock on the card. That could
> get you to a 125 MHz time base with a 8 ns resolution. Again, without
> a deep dive into what they did - who knows.
That is the clock-supply to the 82599 chip, but there is a boatload
of PLL'ery
Hi
> On Jul 4, 2022, at 10:04 AM, Poul-Henning Kamp via time-nuts
> wrote:
>
>
> Poul-Henning Kamp via time-nuts writes:
>
>> The timestamping counter gets its clock from the ethernet line
>> signals, and the counting frequency therefore depends on the ethernet
>> speed:
>>
>>
Poul-Henning Kamp via time-nuts writes:
> The timestamping counter gets its clock from the ethernet line
> signals, and the counting frequency therefore depends on the ethernet
> speed:
>
> 100 Mb/s1.5625 MHz
> 1 Gb/s 15.625 MHz
> 10 Gb/s 156.25
John Miller via time-nuts writes:
> I'm curious if anyone here knows much about these silicom timestamping
> network interfaces?
I used the i82599 ethernet chip ten years ago, to measure time in
the first Adaptive Optics Real-Time Computer prototype we built for
ESO's ELT telescope.
I
Hi
I think the key parameter is the 8 ns resolution on the time stamp.
That may or may not be adequate for this or that application.
Without doing a deep dive on the part, it’s not real clear how they
deal with the accuracy of the onboard timebase. It’s rated at 0.01 ppm
with no real details.
Hi
If you are running a high gain op-amp to buffer things into a
sound card *and* using the same op-amp output to drive the
EFC, then you will have problems.
Simple answer is to use a couple of op amps.
Buffer the mixer with something low noise. Get the output of the
mixer up to the point it
Hey all,
I'm curious if anyone here knows much about these silicom timestamping network
interfaces? They pop up fairly often for sale, usually for not that much. They
have SMA in/out for a PPS signal in addition to the network interfaces. I've
found datasheets like this (linked below), but no
Hi David,
Let me explain the DIY "measurement instrument"
DOCXO into LO port of a mixer, DUT into RF, IF port with low pass filter
to both steer the Vtune of the DOCXO and into an opamp to amplify
1-100kHz into PC audio input. On PC audio spectrum analyzer.
So yes, the limiting factor is the
Mike,
The phase detector is an ADE-1 mixer, the IF output of the mixer goes
into a loop filter that has a corner frequency of about 0.2Hz to enable
Phase noise measurements down to 1Hz offset
Thanks for the excellent references, a lot to study.
Yes, one can do very advanced cross correlation
Typo: 0.01Hz phase offset
S/B: 0.01Hz frequency offset
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Thank you for your detailed description. I wonder what kind of phase
detector you are using. I have never heard of one that required 0.01Hz
phase offset to lock. Even the simplest Phase-Frequency Detector (PFD)
would do orders of magnitude better. Here are some papers:
1. Motorola App. Note
Are you sure the PN floor of the measurement instrument isn't the limiting
factor?
David
-Original Message-
From: Erik Kaashoek via time-nuts
Sent: 04 July 2022 10:14
To: time nuts ; Erik Kaashoek
Cc: Erik Kaashoek
Subject: [time-nuts] DIY Low offset Phase Noise Analyzer
:
At
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