Ed,
Thanks for the many good advice.
I've tried to incorporate as much as possible, updated schematic can be
found here: http://athome.kaashoek.com/time-nuts/PNA/SSPNA.JPG
For audio into the PC I'm using a professional balanced microphone to
USB input with a noise level of -130dBc/Hz and no
Am 2022-07-13 4:10, schrieb glenlist via time-nuts:
Oh and now LED lights overhead your bench which are driven at 5-50kHz
are are next new coupling of noise into your open bench circuits !!!
The LED ringlight on my microscope creates 57KHz noise peaks when I have
an unshielded low noise
Super advice Ed, this is really really good advice.
Erik this is sage advice. especially CMR at high frequencies...
Oh and now LED lights overhead your bench which are driven at 5-50kHz
are are next new coupling of noise into your open bench circuits !!!
Glen.
(RF engineer)
On 13/07/2022
HI
We’re not building a synthesizer here. We are putting together
a simple piece of test gear. The purpose of the test gear is to
measure phase noise down into the -170 dbc / Hz range …..
Bob
> On Jul 12, 2022, at 4:05 PM, Mike Monett via time-nuts
> wrote:
>
> To Bob kb8tq:
>
>
On 7/12/22 3:51 PM, ed breya via time-nuts wrote:
I forgot to mention that you should also consider possible effects
from the RF present, on the LNA. This can be more significant than
SMPS frequencies getting where they don't belong, especially since the
RF is intentionally right at the
Erik, I'd really recommend that you use a real, "solid" ground reference
on the instrumentation side, with +/- large (12-20 V) supplies, as
others have suggested.
Your most recent setup diagram indicates that you're relying on the
"differential" input of the audio PC card etc analyzer to
I forgot to mention that you should also consider possible effects from
the RF present, on the LNA. This can be more significant than SMPS
frequencies getting where they don't belong, especially since the RF is
intentionally right at the opamp's input. Your LPF only reduces, and
does not
On Tue, 12 Jul 2022 08:17:33 -0800
Bob kb8tq via time-nuts wrote:
> Hi
>
> If you have any ceramic capacitors in the mix, they are often
> microphonic. The X7R versions are typically the best “high C” types.
> NPO’s normally are completely non-microphonic. Other non-ceramic caps
> should be ok,
On 7/12/22 8:53 AM, Erik Kaashoek via time-nuts wrote:
I'm struggling with the noise floor.
First tests where done with a 5nV/sqrt(Hz) opamp. Noise floor with
shorted mixer output at 10kHz was -140dBc/Hz. Then I tried with
1nV/sqrt(Hz) opamp, but that made no difference, noise floor at 10kHz
Hi
If you have any ceramic capacitors in the mix, they are often microphonic.
The X7R versions are typically the best “high C” types. NPO’s normally are
completely non-microphonic. Other non-ceramic caps should be ok, but
who knows.
Roughly speaking, 1 nV / Hz should be low enough to not
I'm struggling with the noise floor.
First tests where done with a 5nV/sqrt(Hz) opamp. Noise floor with
shorted mixer output at 10kHz was -140dBc/Hz. Then I tried with
1nV/sqrt(Hz) opamp, but that made no difference, noise floor at 10kHz
was still -140dBc/Hz
The setup was simplified to this
Hi
There are a very small number of signal generators that *might*
help when measuring phase noise on a good source. The “rest
of them” are very much in the “don’t bother” category. Just which
one is in the “maybe” category depends a lot on your frequency
of interest. None of them seem to be
yes there are much better signal generators out there, that frequency
doubler tuning circuit is for religious people only -- you need to be
able to believe, that it could work
73
KJ6UHN
Alex
On 7/11/2022 12:24 PM, Dave B via time-nuts wrote:
On 11/07/2022 08:30,
Hi
Regardless of what you call the “ 1 Hz normalized noise “ of a digital
phase detector, it does predict what the noise floor does on it as the
reference frequency is changed over some reasonable range. This has
been demonstrated a lot of times and on a lot of different parts.
Based on a
On 11/07/2022 08:30, time-nuts-requ...@lists.febo.com wrote:
I also measured a Marconi 2022 signal generator and it was possible to
lock but the phase noise was terrible with strong factional PLL spurs.
Indeed, those signal generators are renown for having "some rather
interesting" spectral
Hi Erik,
On 7/10/22 17:52, Erik Kaashoek via time-nuts wrote:
I've updated the schematic to include the latest additions and added
some new measurements
Schematic: http://athome.kaashoek.com/time-nuts/PNA/Simple_PNA.pdf
The resistor values (many 18k) are a bit weird but I happen to have a
Hi
There’s really no need to use the Vref out of the OCXO at all.
Since many devices don’t have one, you will need a “replacement”
at some point. Simply pulling the “set reference” off of a cleaned
up output of your main supply(s) is typically how it is done.
The most basic reason to not hard
Hi
Pretty much the best mixer to use for this in a basement / DIY basis
is a Mini Circuits RPD-1 or one of it’s siblings. It has a 500 ohm
output on the mix port instead of 50 ohms. Yes, you open circuit
terminate it ( so 5K ) but as noted, it’s the Zout of the mixer that likely
sets what the op
Hi
Yes it is a pain to implement dual supplies. I ponder that issue every time
I build one of these setups. I’ve built a lot of them …. If you are going to
do a single supply, setting up a “virtual ground” is probably the best way
to go. Do it with a drive circuit to provide very clean 15V off
I've updated the schematic to include the latest additions and added
some new measurements
Schematic: http://athome.kaashoek.com/time-nuts/PNA/Simple_PNA.pdf
The resistor values (many 18k) are a bit weird but I happen to have a
big box of 18k resistors.
The value of the low pas filter after
Am 2022-07-10 9:11, schrieb Erik Kaashoek via time-nuts:
@Bob,
You mentioned "dual supplies with high voltage" for the first gain
opamp. How much impact would dual voltage bring as its a pain to
implement.
I think is was Rubiola who wrote that he exploded a costly microwave
mixer
with a
Hi Magnus,
Yes, and it works very well, locking is easier as once locked it nicely
stay's in lock, , even with a slow drift of either the DUT or the
reference. As I could not find a bipolar capacitor the tuning potmeter
has to be kept at the low side to avoid blowing the integration
Erik,
On 7/9/22 22:06, Erik Kaashoek via time-nuts wrote:
Getting the simple PNA to lock was a bit difficult due to the overly
simplistic translation of the mixer output to the Vtune of the OCXO
To get some more flexibility I added a summing opamp that summed the mixer
output with the output of
On Sonntag, 10. Juli 2022 01:24:49 CEST djl via time-nuts wrote:
> I checked the Hittite/AD part at Mouser, $21 and change. Problem is,
> they have a few, but it is marked obsolete/discontinued. Also, a
> devilish package to work with. . .
For a one-off project, lifetime doesn't really matter,
Hi Erik,
On 7/8/22 17:12, Erik Kaashoek via time-nuts wrote:
Not something I want to implement on short notice but maybe for the
future.
The biggest limitation in this DIY PNA is the phase noise of the
reference OCXO and the noise of the opamp amplifying the output of the
mixer.
So I was
I checked the Hittite/AD part at Mouser, $21 and change. Problem is,
they have a few, but it is marked obsolete/discontinued. Also, a
devilish package to work with. . .
On 2022-07-08 22:19, Mike Monett via time-nuts wrote:
To Bob kb8tq. You wrote:
Hi
The noise floor of the double
Hi
(see below)
> On Jul 9, 2022, at 12:06 PM, Erik Kaashoek wrote:
>
> Getting the simple PNA to lock was a bit difficult due to the overly
> simplistic translation of the mixer output to the Vtune of the OCXO
> To get some more flexibility I added a summing opamp that summed the mixer
>
Hi Mike,
On 7/8/22 15:34, Mike Monett via time-nuts wrote:
You wrote:
Mike,
He was using an analog mixer, but your comment about XOR mixer does
not apply to analog mixers. Your oversimplification that analog
mixer and XOR gates being the same thing does not apply here, and
thus the
Getting the simple PNA to lock was a bit difficult due to the overly
simplistic translation of the mixer output to the Vtune of the OCXO
To get some more flexibility I added a summing opamp that summed the mixer
output with the output of the coarse tuning potmeter. As the summing causes
inversion
Hi
As noted in another post, the phase detector guys talk
about a figure of merit that is not directly comparable to
the floor of a DBM. If I translate the -170 dbc/ Hz at 100MHz
on the DBM, to the PLL chip FOM, I would add 80 db. That
would make it a -250 dbc FOM vs the -231.
Since the FOM
HI
> On Jul 8, 2022, at 7:44 PM, Mike Monett via time-nuts
> wrote:
>
> To Erik:
>
> …….
> Another item that might be of interest is the PFD. The Hittite
> HMC984LP4E has -231 dBc/root(Hz) of noise, which is quite low. The
> datasheet is at
>
Hi
> On Jul 8, 2022, at 10:35 AM, Mike Monett via time-nuts
> wrote:
>
> Bob, you wrote:
>
>> Mike. One concern I have with active components as mixer is noise.
>> For an SA I designed only a passive DB diode mixer had low enough
>> output noise. Would a PF detector as being an active
Hi
Indeed you can switch the gain of the amp. You still need to provide
a low gain output to feed the EFC input on your reference. The chain
to feed the sound card will be crazy high gain for the typical TCXO or
OCXO. Don’t even think of running that sort of gain into a VCO ….
Bob
> On Jul 8,
Bob,
Clear, you have a lot more experience and knowledge. For me this is
typical a case of "If you don't know about something it must be simple"
So best would be to make it possible in the simple PNA to switch off the
opamp gain, without changing the impedance the mixer sees, so the
offset
Hi
Like it or not, the mixer is a non-linear load. It also has a frequency
dependence. Even with “saturation” levels, the slope can and does
change. That’s the short list, as you dive into it, things get even more
complex in terms of “might be” sort of issues.
How can you be in saturation and
Bob
This confuses me.
The calibration of the system changes ( or can change ) each and every time you
swap
out signal sources. The levels are not going to be consistent setup to setup.
Thus you
calibrate each and every time you change out either device.
Assuming each source is saturating the
Hi
(see below)
> On Jul 7, 2022, at 10:10 PM, Erik Kaashoek wrote:
>
> Bob,
> You may have explained this before but I still do not understand.
> Does the phase modulation slope at the detector depend on the depth of the
> phase modulation? I think not.
The “phase modulation” you are looking
Not something I want to implement on short notice but maybe for the future.
The biggest limitation in this DIY PNA is the phase noise of the
reference OCXO and the noise of the opamp amplifying the output of the
mixer.
So I was wondering if it would make sense to do the following
1: Split the
Hi,
Well, both amplitudes can be measured. The method I refer to is one of
several out of NIST, so it's not one of my own invention. See their AM
and PM Calibration material.
Using multiple methods you can evaluate how well the method functions.
The side-tone method generates known PM with
Bob,
You may have explained this before but I still do not understand.
Does the phase modulation slope at the detector depend on the depth of
the phase modulation? I think not.
With 57 degrees one should get an output voltage that is to be regarded
as the 0dBc level but this can not be measured
Hi
One consideration:
If you do signal injection for calibration, you have the amplitude
uncertainties on
both the “carrier” and injected signals. The slope at zero on the beat note is
likely
to be *much* more accurate ( even if gain measurement at audio gets thrown in …)
Bob
> On Jul 7,
Hi,
A well established method is to use a separate offset RF generator that
you can steer frequency to form suitable offset and amplitude to form
known level. You can now inject this ontop of a signal to measure.
Consider that you steer your offset frequency to be +1 kHz of the
carrier you
Hi
The idea is partly to lock the two devices. The bigger objective is to hold
the mixer output at the correct zero volt operating point.
Cabling things to a different device and then doing phase correction to keep
things at zero would be a major pain.
Bob
> On Jul 7, 2022, at 5:52 AM, Mike
On 7/7/22 8:55 AM, Bob kb8tq via time-nuts wrote:
Hi
Yes, you do need to know the system gain. Since we are talking about
gain at audio, measuring the gain directly is not a crazy thing to do. One
of the things that makes audio spectrum analyzers a nice tool for this that
they eliminate the
Hi
Yes, you do need to know the system gain. Since we are talking about
gain at audio, measuring the gain directly is not a crazy thing to do. One
of the things that makes audio spectrum analyzers a nice tool for this that
they eliminate the “variable gain to the sound card” issue.
Some sound
Bob, others.
It has been explained that for the best phase noise level calibration on
should use a signal with one radian phase modulation and measure the
output voltage.
The problem with this approach is the unknown gain of the path into the
PC. And due to the gain one can not modulate with
On Tue, July 5, 2022 5:27 am, Mike Monett via time-nuts wrote:
> The phase-frequency detector has zero ripple at lock.
The PF detector also locks at 0 degrees offset. How do you get the
demodulated phase noise out of that?
The point of the a diode mixer is that it locks at quadrature, and the
Mike,
He was using an analog mixer, but your comment about XOR mixer does not
apply to analog mixers. Your oversimplification that analog mixer and
XOR gates being the same thing does not apply here, and thus the
assigned missbehavior does not carry over to the analog mixer case.
Cheers,
Hi,
On 2022-07-05 12:13, Mike Monett via time-nuts wrote:
You stated:
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
That is your problem. A double
Hi
> On Jul 5, 2022, at 9:00 AM, Erik Kaashoek via time-nuts
> wrote:
>
> Mike.
> One concern I have with active components as mixer is noise. For an SA I
> designed only a passive DB diode mixer had low enough output noise. Would a
> PF detector as being an active component, not create more
Mike.
One concern I have with active components as mixer is noise. For an SA I
designed only a passive DB diode mixer had low enough output noise. Would a
PF detector as being an active component, not create more noise as output?
Erik
On Tue, Jul 5, 2022, 18:20 Mike Monett via time-nuts <
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
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