The LT1037 is shown with a gain of ~1690x, if this amplifier is used to
amplify the beat frequency signal, it will saturate.
Opamp recovery from saturation is poorly documented and may be very slow.
It would be better to use some diodes in the amplifier feedback network
to limit the large signal
Brian Kirby wrote:
I am in the process of designing a DMTD system. As an experiment to
do basic measurements on the chosen mixer, I used a capacitor (0.01
uF) in series to ground with a 47 ohm metal film resistor. Where the
capacitor and resistor meets, another resistor is attached (390 ohms)
Gerard PG5G wrote:
Hello all,
First post here, so I'll start with a quick introduction. I trained as
an electronic engineer but don't work in that field any more, which has
given me the appetite back to do some electronic engineering as a
hobby. I have been a licensed ham for
Richard (Rick) Karlquist wrote:
Bruce Griffiths wrote:
Only if the noise figure of the following amplifier is 4dB or so.
With no extra amplification is used one only needs a signal level of
+1dBm to achieve a phase noise floor of -178dBc/Hz if the output is
extracted through the crystal in
Magnus Danielson wrote:
Bruce Griffiths wrote:
Garry Thorp wrote:
With the 723, you can make the reference noise as low as you want, by
heavy RC filtering. This applies whether you use its own reference or a
better external reference.
The 723 also seems to work quite happily with a feedback
Garry Thorp wrote:
With the 723, you can make the reference noise as low as you want, by
heavy RC filtering. This applies whether you use its own reference or a
better external reference.
The 723 also seems to work quite happily with a feedback capacitor from
the output to the inverting input, re
John Miles wrote:
-178 is about the same broadband floor that you see from the higher-end
Wenzel ULN parts. These can be custom-ordered in the $2000-$2500 range in
single quantities. Pascall's product line seems relatively similar.
Obviously the carrier needs to be over +4 dBm to get to -178 dB
Garry
A little more detail is required such as:
1) What was the divided down output of the 74AC163 compared with?
2) An image of the breadboard would also be useful.
3) A circuit diagram showing component values and manufacturer's part nos.
The idea being to provide sufficient information so
http://www.national.com/ds.cgi/LM/LM117.pdf
Audio freaks are discussing it in
http://www.diyaudio.com/forums/solid-state/28978-improving-lm3x7-regulator-circuit.html
Is that what you are looking for?
73
Arnold
On Thu, 25 Feb 2010 11:22:02 +1300, Bruce Griffiths wrote:
You can improv
volts, compared to typically much less for a modern reference.
Didier
Sent from my BlackBerry Wireless thingy while I do
other things...
-Original Message-
From: Bruce Griffiths
Date: Thu, 25 Feb 2010 11:22:02
To: Discussion of precise time and frequency measurement
Su
Bob Camp wrote:
Hi
Since the LPRO has a "noisy" 3 terminal regulator inside it, making the
outside voltage quiet (as in noise density) probably will not help much.
I've seen people insist on a low noise regulator ahead of a fluxgate
magnetometer that used an LM7805 regulator.
The plastic en
Poul-Henning Kamp wrote:
In message<4b85a2eb.4000...@pacific.net>, Brooke Clarke writes:
My old Gibbs rack mount 5 MHz standard used the LM723 linear regulator.
I believe it's one of the lowest noise regulators you can use.
http://www.national.com/mpf/LM/LM723.html#Overview
If you re
You can improve the performance of the LM723 if one substitutes an LM329
for the internal reference biased from the regulator output.
The trick is to use the internal reference for startup and decouple it
with a diode or similar once the LM329 achieves its nominal output.
Currently, there appea
life speed wrote:
From: Bruce Griffiths
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Its easy to calculate a lower bound to the amplifier phase noise floor
from the signal level at the output and the amplifier output noise due
to feedback resistors together with the
Rick Karlquist wrote:
Bruce Griffiths wrote:
He's made similar comments before.
It actually isnt that difficult to achieve an isolation amplifier phase
noise floor below -170dBc/Hz if one is careful to use appropriate parts,
design techniques, and the input signal level is high enough
Martyn Smith wrote:
Hi All,
I read Garry's email about using the 74AC04 as a distribution amplifier.
Did I read it right, does Gary say you will get -178 dBc/Hz at 10 kHz
offset???
Being one of only 3 or 4 companies in the world that manufactures
distribution amplifiers that break the -170
life speed wrote:
If I can believe the simulation (a big if) the ADA4899-1 can provide 90 dB
isolation at 10 MHz, rolling up to 70 dB at 100 MHz, when configured with a
gain of +2
The subcircuit model provided by ADI is useless for noise, unfortunately. I
guess I'll have to build and measure
life speed wrote:
From: "Martyn Smith"
Subject: [time-nuts] Phase Noise of 74AC gates
I'm not about to say how we achieve -170 dBc/Hz phase noise, but we
definitely don't use op amps or logic gates!!
Regards
Martyn
Is this an advertisement? I don't think anybody believes a logic gate p
life speed wrote:
Message: 6
From: Pete Rawson
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Clay,
Analog devices AD4899-1 voltage noise = 2nV/rtHz @ 10Hz; GBW = 300MHz.
Pete Rawson
That is an interesting part.
So, how does one think about reverse isolation in a
Martyn Smith wrote:
Hi All,
I read Garry's email about using the 74AC04 as a distribution amplifier.
Did I read it right, does Gary say you will get -178 dBc/Hz at 10 kHz
offset???
Being one of only 3 or 4 companies in the world that manufactures
distribution amplifiers that break the -170
Gerhard Hoffmann wrote:
Bruce Griffiths wrote:
Not necessarily, it depends on the phase detector circuit details.
What phase detector output termination network did you use?
Aren't BF862's somewhat noisier than 2SK369's at low frequencies?
SRA-3H because I had them, 49R9 in
Gerhard Hoffmann wrote:
Bruce Griffiths wrote:
A preamp like that shown will be best suited to phase detectors with
low gain and output impedance with a resistive output termination
matched to the phase detector.
Phase detectors like the Minicircuits RPD-1, MPD-1 etc have a
relatively
Gerhard Hoffmann wrote:
Bob Camp wrote:
Hi
Ok, A bit more info:
1) Quadrature PLL using an RPD-1 DBM and a home brew lock box. 2)
Willingness to accept that I'm measuring a pair of oscillators
3) Plenty of sources at the appropriate frequencies
4) First took a shot at this in 1975 (I forget
ord at 100 /
32 MHz - not quite as hard.
Bob
On Feb 18, 2010, at 9:54 PM, Bruce Griffiths wrote:
Magnus Danielson wrote:
Bruce Griffiths wrote:
Magnus Danielson wrote:
Bruce Griffiths wrote:
Lux, Jim (337C) wrote:
-Original Message
Magnus Danielson wrote:
Bruce Griffiths wrote:
Magnus Danielson wrote:
Bruce Griffiths wrote:
Lux, Jim (337C) wrote:
-Original Message-
From: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths
Sent: Wednesday, February 17, 2010 2:10 PM
To
A better calibration technique may be to add a known amount of RF noise
(eg from an amplified noise diode or similar) to one of the mixer inputs.
This allows calibration without switching the sound card preamp gain to
a value different from that used to make measurements.
The added RF noise only
Baudline only uses 16 bit samples a significant limitation if one has a
high end sound card.
Bruce
John Ackermann N8UR wrote:
For Linux (and I think some other *nixes) check out Baudline
(http://www.baudline.com). It's free but not open source. It's a
general purpose audio spectrum analyzer
life speed wrote:
The TI THS3201-EP was looking pretty good for a high speed opamp. But the
input current noise graph doesn't go below 100 KHz and is climbing pretty
steeply at that point.
Clay
Most current feedback opamps tend to have high inverting input noise
current at low frequenc
Hal Murray wrote:
The problem is modulation of the reference signal via relative
movement of the transformer guts. While I understand there are ways
to 'harden' magnetic devices, my application is far too sensitive to
even consider a magnetic approach given the availability of
alternatives.
life speed wrote:
Date: Thu, 18 Feb 2010 15:22:40 +1300
From: Bruce Griffiths
Clay
What's the effect of assigning the same label (Vout_2) to the outputs of
both output amplifiers as shown in your circuit schematic?
Bruce
Hi Bruce,
Duplication of the Vout_2 net labels (copy and pas
.@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bruce Griffiths
Sent: Thursday, February 18, 2010 7:28 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] DMTD to MMTD
Magnus Danielson wrote:
Bruce Griffiths wrote:
Lux, Jim (337C) wrote:
---
Using an amplifier with AGC like the MC1590 is a sure method of ensuring
high flicker phase noise and a high phase noise floor.
The emitter followers by themselves provide insufficient reverse
isolation for most applications.
Usually one requires 0dB (or perhaps more) gain so that an input preamp
Magnus Danielson wrote:
Bruce Griffiths wrote:
Lux, Jim (337C) wrote:
-Original Message-
From: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths
Sent: Wednesday, February 17, 2010 2:10 PM
To: Discussion of precise time and frequency
Scott Burris wrote:
I'm finally thinking about building some real power supplies for my
Thunderbolts
and LPRO-101, and that got me thinking about the topic of low noise power
supplies again.
I think Dr. Bruce and I exchanged some messages about this a year or
two ago,
when I was looking at "RF
Clay
What's the effect of assigning the same label (Vout_2) to the outputs of
both output amplifiers as shown in your circuit schematic?
Bruce
life speed wrote:
Date: Fri, 12 Feb 2010 15:32:55 -0500
From: Bob Camp
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Hi
There ar
life speed wrote:
Date: Fri, 12 Feb 2010 15:32:55 -0500
From: Bob Camp
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Hi
There are a few differences between what you are simulating and the schematics
Bruce posted earlier. The collectors of the input stages (q1, q4 and q7) see
be a bit of a
tangle that way, not as easy as it used to be.
Bob
On Feb 17, 2010, at 7:20 PM, Bruce Griffiths wrote:
Lux, Jim (337C) wrote:
I don't know if there's a FIFO in front of the UART (e.g. what if you get
simultaneous zero
crossings).. but I would
Lux, Jim (337C) wrote:
I don't know if there's a FIFO in front of the UART (e.g. what if you get
simultaneous zero
crossings).. but I would expect there is.
The "hard work" is in the zero crossing detector ahead of the FPGA. (and
perhaps in the latching of
the ZCD input
Lux, Jim (337C) wrote:
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf
Of Bruce Griffiths
Sent: Wednesday, February 17, 2010 2:10 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] DMTD to MMTD
The
rces. My
assumption is that you could simply use a bunch of DMTD's and then do the
math. You might also be able to simplify things a bit
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bruce Griffiths
Sent: Wednesday, February
Bruce Griffiths wrote:
Bob Camp wrote:
Hi
DMTD looks at a pair of sources (crystal, rubidium, maser .) and
tells you
the difference between them. If you looked at more than two, you can
better
characterize the individual sources.
Any good papers out there on taking the DMTD approach
Lux, Jim (337C) wrote:
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf
Of Bob Camp
Sent: Wednesday, February 17, 2010 1:57 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] DMTD to MMTD
Hi
Thanks for
Bob Camp wrote:
Hi
DMTD looks at a pair of sources (crystal, rubidium, maser .) and tells you
the difference between them. If you looked at more than two, you can better
characterize the individual sources.
Any good papers out there on taking the DMTD approach and extending it to
simultaneo
t what you need. More parts than a pure op amp design, more current. Likely
easier to get running.
Lots easier to do with a couple transformers in there.
Bob
On Feb 12, 2010, at 11:02 PM, Bruce Griffiths wrote:
The only data available seems to be John Ackermann's measurements on the TADD
ey do supply and make an
guess based on how the noise rolls up over the range they do show.
An op amp circuit would certainly would take fewer parts, and likely more
current. No free lunch
Bob
On Feb 12, 2010, at 10:11 PM, Bruce Griffiths wrote:
In the later version the input amplifie
wrote:
Hi
Since it's the input stage, it's likely the point most impacted by a higher
flicker noise part. That might make one want to look at alternatives.
Of course, it's not real clear that a super low noise amp is needed in this
case.
Bob
On Feb 12, 2010, at 8:46 PM, B
of the upper emitter resistor bypasses to
ground rather than B+. Another alternative would be emitter to emitter bypass
as shown on the JPL schematic. I'm guessing both would improve isolation in a
real world circuit.
Bob
On Feb 11, 2010, at 8:34 PM, Bruce Griffiths wrote:
life
life speed wrote:
I seem to not be accomplishing much isolation from output to input, as well as
output to output. Have I fumbled PSPICE somehow? For each simulation, Vac was
set separately, with V1=0.707V at the input, while V6=0V at the output (sim1).
Then V1=0V, and V6=0.01V (sim2).
(well above the
Nyquist limit) to allow this without using WSK interpolation to estimate
the signal value between the samples.
thanks, it's always fun to read your comments
ws
*
Bruce
- Original Message - From: "Bruce Griffiths"
To: "Discussion of pre
life speed wrote:
Message: 2
Date: Fri, 12 Feb 2010 12:12:29 +1300
From: Bruce Griffiths
The output (collectors of Q5, Q6 emitter of Q4) of the input amplifier
sets the dc voltage at the inputs ( Q1 base, Q7 base respectively) of
the output amplifiers.
The circuit consists of a unity gain input
If one follows that diagram blindly one will encounter a few problems
with a 10MHz mixer/phase detector input frequency.
1) The PLL is a first order loop and the frequency of the OCXO being
servoed to the oscillator under test has to be carefully adjusted to be
close to that of the oscillator
life speed wrote:
Message: 1
Date: Thu, 11 Feb 2010 12:42:27 -0500
From: "Bob Camp"
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
amplifier(Clay)
Hi
I really should learn how to read the whole message
Cancel the second request on vibe info.
-
The gotcha
life speed wrote:
Message: 2
Date: Thu, 11 Feb 2010 07:54:40 -0500
From: Bob Camp
Hi
Implementing that circuit without using a hybrid would be a bit of a challenge.
Bob
Message: 6
Date: Fri, 12 Feb 2010 04:09:08 +1300
From: Bruce Griffiths
Yes implementing an exact copy without using a
the method are false.
You admit to not knowing how to calculate how your implementation
responds to different phase noise spectra and yet you confidently
proclaim there will be no problems in interpreting the results?
Bruce
***
- Original Message ----- From: "Bruce
or so it shouldn't
be too much of a problem.
At 10MHz 2N3906 and 2N3904 transistors should suffice.
Bruce
Bob Camp wrote:
Hi
Implementing that circuit without using a hybrid would be a bit of a challenge.
Bob
On Feb 10, 2010, at 11:30 PM, Bruce Griffiths wrote:
Clay
Circuit sch
circuit to improve stability and increase the reverse isolation
slightly.
Bruce
Bruce Griffiths wrote:
Clay
You could try something like the attached circuit schematic.
Austron used buffer amplifiers like this albeit without the
complementary symmetry output stage.
There are no transformers
John
As far as I can tell only one copy of one of my recent messages was
added to the time nuts archives.
However 2 copies appear to have been sent to those on the list.
My machine indicates that only one copy was posted to the list.
Bruce
___
tim
Attn: John Ackermann
Not sure what happened to produce 2 identical posts but as far as I can
tell I only posted this once.
Bruce
Bruce Griffiths wrote:
Clay
Circuit schematic for a more recent JPL isolation amplifier design is
attached.
Bruce
Clay
Circuit schematic for one of the JPL isolation amplifiers is attached.
Unfortunately (apart from the few I and others may have) these
transistors are difficult to obtain.
However modern equivalents could be substituted.
Bruce
life speed wrote:
Avoiding transformers and inductors will ma
Clay
You could try something like the attached circuit schematic.
Austron used buffer amplifiers like this albeit without the
complementary symmetry output stage.
There are no transformers and the dc gain is low.
Simulated reverse isolation at 10MHz is around 120dB.
Simulated crosstalk between
life speed wrote:
Hello everyone,
I am new to this list, happened across it while searching on distribution
amplifiers.
I need to design a 10 MHz isolation/distribution amplifier with two outputs for
a high-vibration wide temperature range environment. I was considering using a
design based
It is essential to understand exactly how this system works in theory.
No amount of hand waving or protestations will make its problems go away
if you use inappropriate signal processing methods.
The tight PLL (or any other PLL) forces the VCO (VCOXO int this case) to
servo the fluctuations in
Not if one uses a balun.
Bruce
Max Robinson wrote:
Bruce wrote.
A full wave rectified sinewave has only even harmonics present.
True, but it needs a center tapped coil.
Regards.
Max. K 4 O D S.
___
time-nuts mailing list -- time-nuts@febo.c
Thats not very useful when you want the 4th harmonic as its amplitude is
zero fro a 25% duty cycle.
Using a duty cycle of 1/8, 3/8 or 5/8 will maximise the amplitude of the
4th harmonic.
see:
http://www.wenzel.com/pdffiles1/pdfs/choose.pdf
Bruce
Max Robinson wrote:
If you start with a square
A full wave rectified sinewave has only even harmonics present.
Bruce
Max Robinson wrote:
If you start with a square wave odd order is all you can get but if
you start with a pulse with a 25% duty cycle you can get even order.
It's best to optimize the pulse width for the harmonic you want.
If you must roll you own 64MHz crystal oscillator you can eliminate the
problems associated with parasitic oscillation in the sustaining
amplifier by using a low phase noise unconditionally stable MMIC (eg
ERA-5SM) as the sustaining stage.
A diode limiter in the feedback path that includes the
Murray Greenman wrote:
Now I realize I'm known as an injection locking fan, but here's my 2
cents worth:
Divide 10MHz by 5 to 2MHz using a Johnson ring counter (74HC4017). Use
that to injection lock a 64MHz XO. A low noise solution and no PLLs
required.
I'd not be surprised if you could injecti
Nick Foster wrote:
From: b...@iaxs.net
To: time-nuts@febo.com
Date: Tue, 9 Feb 2010 18:24:39 -0600
Subject: Re: [time-nuts] Low phase noise VCO
Which leads me to ask a novice question:
Why not pull a 16 MHz crystal and multiply to 64 MHz?
If you count down from 64 to 10 MHz, isn't the mult
You need to use a mixer with low dc offset for best results.
Try one of the Minicircuits phase detectors (RPD-1, MPD-1, SYPD-1 etc)
These have low dc offset and dc offset drift.
Bruce
Raj wrote:
Hi Dan,
Low tech. Yes! IMHO I think its easier for my mind to track an analog
indication
John Ackermann N8UR wrote:
Sal, what sweep time are you using on the scope? I believe the TBolt
PPS is only microseconds wide, so you may need to speed up the sweep
time to around 100us/div or faster to see it accurately. And you may
need to mess with delaying the sweep to get the pulse on th
, unfortunately I don't have a digital oscilloscope.
Best regards,
Sal C. Cornacchia
Electronic RF Microwave Engineer (Ret.)
From: Bruce Griffiths
To: Discussion of precise time and frequency measurement
Sent: Sun, February 7, 2010 8:17:08 PM
Subjec
continuity, also check the solder joint
between the BNC inner conductor and the PCB.
Bruce
Bruce Griffiths wrote:
Any idea what the pulse shapes you see is with a 1M load and with a 50
ohm load?
Bruce
SAL CORNACCHIA wrote:
Hi Didier,
When the 50 ohms termination is switch on the oscilloscope
Any idea what the pulse shapes you see is with a 1M load and with a 50
ohm load?
Bruce
SAL CORNACCHIA wrote:
Hi Didier,
When the 50 ohms termination is switch on the oscilloscope there is a tiny positive dot deflecting every second, it appears to have a very low output.
Best regards,
Sal
Magnus Danielson wrote:
Bob Camp wrote:
Hi
My main concern with the low frequency pole in the sound card is the
quality of the R/C used. You can certainly model what ever you have.
If they used an aluminum electrolytic for the "C" it may not be the
same next time you check it
Do consi
Hz higher often came at
or above 4x10^-12.
Bob
On Feb 6, 2010, at 9:40 PM, Bruce Griffiths wrote:
As a matter of interest just how bad were those OCXOs?
e.g. what was the ballpark ADEV for 1s, 10s etc.?
Bruce
Bob Camp wrote:
Hi
Occasionally you also come across 5.55 MHz O
when
they move the crystal 55 Hz. Same vendor crystal, same crystal spec., same
oscillator circuit, not even close on short term stability
Bob
On Feb 6, 2010, at 9:02 PM, Bruce Griffiths wrote:
JPL resorted to using a commercial synthesiser set for an offset of 123Hz (to
minimise spur
parts are cheap, and performance is usually a lot easier to check than at RF.
Bob
On Feb 6, 2010, at 8:30 PM, Bruce Griffiths wrote:
Which just leaves the minor problem of the offset oscillator.
One option is to use a phase truncation spur free output frequency from a DDS.
If one is using the
noise floor limit to use for a "low
cost & simple" configuration.
BTW
A well setup "Tight Phase-Lock Loop" method will go below that..
and a good HP 10811A can go below 1e-12 at 0.1 sec. (at a bandwidth
of 30 Hz)
ws
***
Bruce Griffiths said:
The noise of
an internal high pass digital filter.
Its not too difficult to measure the sound card frequency
response using a white noise source for example.
Bruce
On Feb 6, 2010, at 6:12 PM, Bruce Griffiths wrote:
If one has a high end sound card then it could be
Pete
Not sure how you implemented the 4ms holdoff.
With a 5370A/B I would have cascaded a pair of 74HC4059's to divide down
f1(~10MHz) produce a 200Hz (or whatever frequency desired eg 10Hz, 1Hz
etc) signal to drive the external ARM input.
Connected f1 to the START input and f2 (~ 10MHz but ca
using a
white noise source for example.
Bruce
On Feb 6, 2010, at 6:12 PM, Bruce Griffiths wrote:
If one has a high end sound card then it could be used to implement the
bandpass filter and replace the zero crossing detector.
It may be necessary to insert a pilot tone to calibra
ny other Ref Osc that most Freq nuts have.
SO Seems like that is GOOD enough noise floor limit to use for a "low
cost & simple" configuration.
BTW
A well setup "Tight Phase-Lock Loop" method will go below that..
and a good HP 10811A can go below 1e-12 at 0.1 sec. (at a ba
appreciate any comments or observations on the SIMPLEST
scheme for making stability measurements at 1e-13 in one sec."
ws
Bruce
**
- Original Message - From: "Bruce Griffiths"
To: "Discussion of precise time and frequency measurement"
Sent: Saturd
elf and that stuff's
not an issue.
Bob
My sound card has a 1Hz cutoff RC high pass input filter plus an
internal high pass digital filter.
Its not too difficult to measure the sound card frequency response using
a white noise source for example.
Bruce
On Feb 6, 2010, at 6:12 PM, Bruce
In a dual mixer system isolation is more critical to avoid locking
between the 2 sources being compared.
Isolation amplifiers with 80dB or more reverse isolation and low phase
noise are inexpensive requiring 3 or 4 transistors (depending on the
desired isolation) if you build your own.
One c
data for 2 channels of 24 bit samples at 192KSPS
will result in a file with a size of at least 1.15GB.
Bruce
Bruce Griffiths wrote:
If one were to use a bandpass filter with a Q of 10 to filter the beat
frequency output of the mixer, then if the input frequency is 10MHz
and the filter
A round robin test where a couple of well characterised oscillators are
passed around for intercomparison is perhaps the ideal method of
evaluating such effects.
Bruce
WarrenS wrote:
Bob
So, if your point is that there are other ways to do it. ...We Agree
(And the reason for the advanced me
can see no obvious reason it would not be true
on DMTD.
Bob
On Feb 6, 2010, at 5:12 PM, Bruce Griffiths wrote:
The only major issue with DMTD systems is that they undersample the phase
fluctuations and hence are subject to aliasing effects.
The low pass filter has to have a bandwidth of the
SIMPLEST
scheme for making stability measurements at 1e-13 in one sec."
ws Answer) Try the "Tight Phase-Lock Loop Method"
ws
**
- Original Message - From: "Bruce Griffiths"
To: "Discussion of precise time and frequency measurement"
Sent:
Bruce Griffiths wrote:
The tight PLL method doesn't directly produce the average frequency
over Tau.
As explained in (see snapshot of relevant section):
NIST special Publication 1065 Handbook of Frequency Stability Analysis
<http://tf.nist.gov/timefreq/general/pdf/2220.pdf>
the averag
The only major issue with DMTD systems is that they undersample the
phase fluctuations and hence are subject to aliasing effects.
The low pass filter has to have a bandwidth of the same order as the
beat frequency or the beat frequency signal will be significantly
attenuated.
Since the phase is
To a first approximation injection locking alters the loop parameters so
its important to measure the actual PLL characteristics with the loop
closed and not just use the PLL parameters inferred from the OCXO EFC
transfer function etc.
The noise of the OCXO used as a VCXO will limit the noise
Sounds good but you still haven't found its Achilles heel:
The frequency measures need to be integrated (either implicitly or
explicitly) to produce phase measures which can then be used to
calculate ADEV, MDEV etc.
The major problem is that integration amplifies the small errors that
are inev
Pete
The paper on the filter approach to ADEV etc is:
http://arxiv.org/pdf/0904.2660
Bruce
Bruce Griffiths wrote:
_Correction_
Oops, Its the CNT91 not the CNT81 that actually does the regression fit.
How did you achieve MDEV ~1E-13 @10s with a counter rated at 50ps
single shot resolution
_Correction_
Oops, Its the CNT91 not the CNT81 that actually does the regression fit.
How did you achieve MDEV ~1E-13 @10s with a counter rated at 50ps single
shot resolution?
Bruce
Bruce Griffiths wrote:
Read the data sheet and the various application notes/white papers on
the Pendulum
Read the data sheet and the various application notes/white papers on
the Pendulum site.
The intrinsic resolution of the Pendulum counter (50ps) is slightly
inferior to that of the SR620 and HP5370A/B.
What they do is statistically process the results of a series of
measurements of the input pha
Pete Rawson wrote:
Efforts are underway to develop a low cost DMTD apparatus with
demonstrated stability measurements of 1E-13 in 1s. It seems that
existing TI counters can reach this goal in 10s. (using MDEV estimate
or 100+s. using ADEV estimate). The question is; does the MDEV tool
provide an
Gerhard Hoffmann wrote:
paul swed wrote:
Well not having a lot of luck with the xilinx wise application.
Its a 6.5 GB tar and after a good 5 hr plus download the tar doesn't
open
with zipgenious
But 6.5 GB to work a cpld. Seems crazy to me.
I also had no luck two weeks ago with the single fil
.
Its a 6.5 GB tar and after a good 5 hr plus download the tar doesn't open
with zipgenious
But 6.5 GB to work a cpld. Seems crazy to me.
On Thu, Feb 4, 2010 at 3:06 PM, Bruce Griffiths
wrote:
Lux, Jim (337C) wrote:
On 2/4/10 9:28 AM, "Bob Camp" wrote:
Hi
Lux, Jim (337C) wrote:
On 2/4/10 9:28 AM, "Bob Camp" wrote:
Hi
From the Altera doc's on the Max II:
There's an oscillator in there to clock the flash (page 2-20). It runs at
around 5 MHz. Need to turn that off. Since standby current is rated at 25ua
it's something that can be done. Lo
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