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Magnus Danielson wrote:
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From: Bill Hawkins [EMAIL PROTECTED]
Subject: Re: [time-nuts] Timing on Ethernet
Date: Sun, 5 Aug 2007 16:25:36 -0500
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Neville Michie wrote:
Thinking outside the square
What you need is a low frequency transmitter exactly in the middle of
the ring...
Neville Michie
Neville
Isn't the accelerator located underground?
Bruce
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Neville Michie wrote:
Hi,
Low frequencies penetrate the ground to some depth.
However, propagation may vary seasonally as groundwater
concentrations change.
cheers, Neville michie
Neville
Even without the seasonal
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Thomas A. Frank wrote:
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Ah, but what if one used the tunnel itself as a waveguide, and
propagated an RF signal down it? Would it then reliably arrive
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Pablo Alvarez Sanchez wrote:
Dear timing colleges,
At CERN we are considering the possibility of using Ethernet as a real
time field bus.
We may use IEEE 1588 to distribute precise UTC and Ethernet Powerlink or
a
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Henk ten Pierick wrote:
However if one adopts a non linear control theory approach, one can
actually design high order modulators that both stable in theory
and in
practice.
Unconditionally? Do you have a link for
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Henk ten Pierick wrote:
On Jul 24, 2007, at 1:32, Dr Bruce Griffiths wrote:
Perhaps a software implementation of a 1 bit oversampled DAC the 1 bit
output of which is low pass filtered to control the EFC input
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Don Collie wrote:
Please excuse my ignorance [I marvel/wonder at some of the essotevric
comments on this group], but why are atomic clocks reliant on these two rare
elements? - why not mercury, or water vapor, they are a lot
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Bob Paddock wrote:
On Friday 27 July 2007 04:14, Dr Bruce Griffiths wrote:
22GHz,
(15GHz)
(~40.5 GHz) than either the caesium
(9.192GHz) or rubidium
(6.8GHz)
Anything happening in the THz range, that anyone
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Jason Rabel wrote:
I have a NTS-200 on the way, but one thing about them is their GPS power
output is 12V instead of the usual 5V. I really didn't want to modify the
board any in an irreversible fashion so I was hoping to build an
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Brooke Clarke wrote:
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Hi Didier:
Would you elaborate on the comment Gold plated connectors are a well known
example. Do you mean when soldered with Lead Tin
Tom Van Baak wrote:
This sure sounds like a more complicated measurement than is necessary
to me. If you have a 10 MHz oscillator, simply feed it into the D
input into a latch clocked by the de-sawtoothed GPS 1PPS. The output of
the latch is a 0 or 1 depending on the precise phase of the
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Magnus Danielson wrote:
Hej Bruce,
Oscillation/cycling of oven temperature?
Oven controller oscillation?
Might be, but then my loadingcondition has caused the oven control out of
stability. This would certainly
Hej Magnus
Since the 10811 oven heater supply in a 5370 is unregulated one possible
cause is a quasi periodic variation of the mains supply voltage.
Bruce
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To unsubscribe, go to
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Mike Feher wrote:
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I believe it is almost impossible to have an intermittent thermal fuse due
to their very clever design. Although over age they can open up. Once
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[EMAIL PROTECTED] wrote:
Thanks Bruce
I've got it sorted now, for the time being at least:-)
I'd love to use a better OS, have tried a few flavours of Linux for
example after spending a long time
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M. Warner Losh wrote:
In message: [EMAIL PROTECTED]
Dr Bruce Griffiths [EMAIL PROTECTED] writes:
: If one booted a FreeBSD machine with an active GPS timing receiver
: connected to a serial port, the serial buffers
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Ulrich Bangert wrote:
Richard,
metastability is an effect that happens when the setup times of an
d-flipflop are not met. This can happen (with a certain statistical
likelyhood) when the sources of the data input and the clock
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Tom
Tom Van Baak wrote:
Bruce,
I like your point about the random quantization error in the
sawtooth. Yes, that would help the noise by a few dB.
On the other hand it would also seem the 10 ns resolution
of the TIC is the
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Richard H McCorkle wrote:
Gentlemen,
I would like to pose a theory question and see if my thinking is
faulty. My original design used a 50 MHz TIC clock and the TMR0
prescaler as the phase counter giving 20ns single sample
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Alan Melia wrote:
Bruce I find this an interesting thread...one maybe naive thought..
it would be nice to have atoo-good stability on the 100MHz TIC but
detracts from the averaging (My interpretation), this almost suggests
Tom Van Baak wrote:
The simpler and cheaper D
flipflop precedence detector used together with hardware sawtooth
correction has far higher resolution. It also has the advantage of not
requiring any high frequency clocks.
Bruce
Since Rick Dr TAC brought it up some months ago, does
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[EMAIL PROTECTED] wrote:
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In a message dated 19/07/2007 02:44:42 GMT Daylight Time, [EMAIL PROTECTED]
writes:
My suggestion is that you pick up a free
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Richard H McCorkle wrote:
With the discussions here on metastable states in TIC
counters, I am asking the experts on the list for their
opinion if the performance of this design would improve
by adding a shift register
Pablo Alvarez Sanchez wrote:
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Hi,
I am curious about the total stability of Cs clocks. Normally producers give
you an initial accuracy after 30 minutes of power on and a table with the
Allan deviation for different
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Tom Van Baak wrote:
The given specs are conservative (in typical HP style) but
I would guess the best ADEV numbers are only for laboratory
conditions. Someone from Agilent/Symmetricom might want
to comment on this.
In the
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Hej Magnus
Magnus Danielson wrote:
Further investigations have now shown that the 10811 output is clean, just a
little 3rd harmonic but nothing to worry about. The INT test point is also
clean. I suspect the output drive part, as
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Peter Vince wrote:
Hi Bruce,
With a quick search of the NIST site, I couldn't find any
mention of this, and the circuit diagram in your GIF was a little
small and fuzzy: is that a crystal on the centre-tap of the
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[EMAIL PROTECTED] wrote:
Hi Bruce,
nice circuit. Many questions:
I wonder how well it works to get a 5MHz source up to 10MHz?
Also, would you have recommendations on the transformer part numbers?
(MiniCircuits,
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Said
To give some idea of the transformer ratios required a simulation using
pSpice shows that:
When using 2 x 2N4393's connected in parallel (limited choice of JFETs
available) for each JFET in the NIST circuit, an input
[EMAIL PROTECTED] wrote
Thanks for the info Bruce, Magnus,
I will be reading the Felton paper to get more info.
With a bit of trickery, I bet this circuit can be used with Bipolar
transistors.
bye,
Said
Said
You mean like the circuit in the attached file?
Input transformer
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[EMAIL PROTECTED] wrote:
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In a message dated 7/9/2007 18:34:30 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Since JFETS have a relatively large spread
The schematic for a NIST developed, low phase noise frequency doubler is
attached.
This device appears to perform significantly better than the Wenzel FET
doubler specifications at least in the flicker noise region.
With suitable modifications to allow individual adjustement/selection of
the
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Mike Feher wrote:
Interesting. Diode doublers of this configuration have been around for about
40 years, and of course so have their FET counterparts. While I never did an
investigation on any additive residual noise, since
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Mike Feher wrote:
Well, I guess that is according to NIST. I do not see how an active doubler
can have lower noise than a passive one, especially when the original signal
has already been degraded by 20log2, or 6 dB so the
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Brooke Clarke wrote:
Hi Bruce:
The common pin has a 100 ns period wave at + and - 500 mv.
One of the center pins on the INT/EX switch had + and - 1 volt at 100 ns
period.
Have Fun,
Brooke Clarke
http://www.PRC68.com
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S McNamara wrote:
G'Day All,
I just purchased a 2nd hand HP5370B counter.
It was last calibrated in 2002 but fails the operators checks.
I have run tests 1-21 and only a few fail.
In step 13 the display indicates 90.9*ns
In
Bob Paddock wrote:
On Saturday 30 June 2007 10:15, Dr Bruce Griffiths wrote:
Not true, there's nothing magic about amplifier saturation, any means
that limits the amplifier output whilst dropping the small signal gain
to a low value will have exactly the same effect
Bob Paddock wrote:
These devices are a little noisy below 100Hz.
Rather than constantly battle the there is to much noise, what are
your thoughts on deliberately injecting out-of-band noise?
As an example:
http://www.analog.com/UploadedFiles/Application_Notes/319765654AN-410.pdf
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Bob Paddock wrote:
The AD8036 and AD8037, from Analog Devices, are wide bandwidth, low
distortion clamping amplifiers.
The AD8036 is unity gain stable. The AD8037 is stable at a gain of two or
greater.
These devices allow
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Brooke Clarke wrote:
Hi:
The DG535 Four Channel Digital Delay/Pulse Generator shows
Ext Clk Error on power up.
The obvious thing to do is turn the rear panel switch to INT, but after
powering up with the switch in either
Pete wrote:
Bruce,
A few final thoughts.
1. Thanks for the critical view; it does help.
2. Like many time-nuts I have a reasonably good 10MHz source
sometimes need to check out a newly acquired OXCO to ensure
it can muster 1E9 or 1E10 performance (with 10x headroom).
An SR620 would be
Ulrich Bangert wrote:
Pete,
5. Mini-circuits BLP-1.9 low pass filter.
terminating the mixer if output with an lowpass/bandpass filter and NOT
with an diplexer is not so good an idea. Where does the rf go?
Best regards
Ulrich Bangert
Ulrich
This depends on whether the
Pete wrote:
Bruce,
This idea is NOT intended to rival the JPL results. Instead,
it's intended to be cheap, easy to replicate allow rather
low cost instruments to be used to compare good sources
to parts in 1E12, quickly. The 1KHz heterodyne frequency
makes life much easier than 1Hz. Noisy
WB6BNQ wrote:
Bruce,
Can you provide a link to the JPL system you reference above ?
Thank you,
BillWB6BNQ
Bill
http://ntrs.nasa.gov/index.jsp?method=orderoaiID=19910016462
http://ntrs.nasa.gov/index.jsp?method=orderoaiID=19910016462
There is also, or was, a free to download
Pete wrote:
Here is a scheme that seems to work well for comparing stable frequency
sources in the range of 10 to 100 second measurement intervals.
Objective - Measure frequency to +/-2E-12 in less than 1 minute.
Method - Heterodyne DUT output to 1KHz with a master reference source +
Tom
Tom Van Baak wrote:
In the case of the 5370, page 3-12 of the manual is where it came from (15.
Press STD DEV and +/- TI switch. Display should read less than 100 ps (this
reading is the instrument's jitter).)
I'm wondering if it would be more informative to make three
runs: one
[EMAIL PROTECTED] wrote:
Hi Bruce,
sounds like I can probably do the 200MHz multiplier board adjustment. I
wonder how much improvement that by itself, with the hardware mods will give?
I'm
just afraid to make things worse.
I used to work with TV's, and it took me years to learn
[EMAIL PROTECTED] wrote:
Hi Tom,
this was the recommended setup (by HP) for checking the internal noise. Feed
the 10MHz output back to the input using a short cable, and set the unit for
COMMON input, setting 50 Ohm impedance etc.
In the meantime I did some more tests, and found the
[EMAIL PROTECTED] wrote:
Hi Bruce,
just found out that the 10MHz output looks very much like the picture in the
5370B service manual.
I am not impressed. HP could have done a better job on that output :( Maybe
my unit isn't broken after all, maybe the 200ps RMS jitter is normal?
John Miles wrote:
Pretty similar results here, taken from the 5370B's rear-panel output while
running on the internal 10811B (attached). Indicated jitter with this setup
is about the same as it was on the ext ref via the 5087A (10-12 ps).
I've seen this counter return self-test jitter
John Miles wrote:
Pretty similar results here, taken from the 5370B's rear-panel output while
running on the internal 10811B (attached). Indicated jitter with this setup
is about the same as it was on the ext ref via the 5087A (10-12 ps).
I've seen this counter return self-test jitter
Bill Beam wrote:
Mike,
I was afraid someone would say 'Riemann tensor'
The problem with the Riemann tensor is that I don't
think that anyone here can write in down in detail
for this problem (let alone solve it). I surely can not.
I also don't think that anyone here is ready for the
idea
Tom Van Baak wrote:
A Measurement of the Period Stability of a Free Pendulum
http://www.leapsecond.com/history/1996-DeMarchi-Pendulum-Stability.pdf
Clever solution. His optical gap is something like 5 microns.
/tvb
An additional issue is the pointing instability of the laser used.
A
Poul-Henning Kamp wrote:
In message [EMAIL PROTECTED], Peter Vince writes:
I have seen something similar with my 53132A. I was checking
on the delay variation of an amplifier distributing 10 MHz, and
noticed a regular sinusoidal pattern, about a third of a nanosecond
Bill Beam wrote:
Assume satellite in circular orbit. (Not really necessary.)
Assume test mass's released at rest wrt satellite center of mass.
Inner test mass released closer to Earth and outer released farther
from Earth. Also assume no air currents, no relativity, no luminiferous
Robert Atkinson wrote:
Hi,
I'd have to agree with Said,
FEI got hit with fines for shipping 1000B OCXO's that were diverted to a
proscribed country. Most major countries that are allies of the USA
should be OK though.
It's surprising what is controlled, very high speed 'scopes, low
Poul-Henning Kamp wrote:
In message [EMAIL PROTECTED], Dr Bruce Griffiths writes:
Robert Atkinson wrote:
The actual controlled export items in the new lists were revised
recently and such crystal oscillators no longer appear to be a
controlled item.
But interestingly
Bill
Bill Beam wrote:
On Tue, 29 May 2007 16:31:40 +1200, Dr Bruce Griffiths wrote:
Ulrich, Didier
Talking about forces, gravitational fields etc makes no physical sense
if the observer's reference frame isn't specified.
For an observer in/on a satellite orbiting about the Earth
Ulrich, Didier
Talking about forces, gravitational fields etc makes no physical sense
if the observer's reference frame isn't specified.
For an observer in/on a satellite orbiting about the Earth with their
reference frame fixed with respect to the satellite.
There is no gravitational field,
Neville Michie wrote:
Hi All,
I am still having difficulty getting my head around the gravity point.
Now I accept, in principle, that due to relativity an intense
gravity field will slow a clock.
My problem is visualising where you will find this field.
At the centre of this planet
Rex wrote:
On Sat, 26 May 2007 19:54:21 -0700, Tom Van Baak [EMAIL PROTECTED]
wrote:
Even fused silica is unstable (see attachment).
Single crystal materials should be significantly better.
Ageing Invar doesn't do much for its dimensional instability.
Bruce
Nice plot. Thanks
Said
Part of the confusion probably stems from such gems as:
Technical Notes:
1.
A resolution of n bit corresponds to a quantization of 2n levels.
Random snippet from Supplement No1 to Part 774.
Bruce
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[EMAIL PROTECTED] wrote:
In a message dated 5/27/2007 16:10:46 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Technical Notes:
1.
A resolution of n bit corresponds to a quantization of 2n levels.
Random snippet from Supplement No1 to Part 774.
Bruce
Brooke Clarke wrote:
Hi Mike:
Back in the 1800s clock makers found ways to temperature compensate the
pendulum such as putting a Mercury thermometer at the bottom, using metals
with
dissimilar expansion coefficients (Harrison used steel and bronze (no zinc
then)) or materials with
Tom Van Baak wrote:
Depends on what you mean by real clocks. The best pendulum
clocks, made in the early 1900's, solved almost all the normal
sources of error and instability. That left gravitational tides as
the one of the few remaining sources of error, down well below
the 1 ppm level. I say
Tom Van Baak wrote:
Even fused silica is unstable (see attachment).
Single crystal materials should be significantly better.
Ageing Invar doesn't do much for its dimensional instability.
Bruce
Tom
Nice plot. Thanks Bruce. Where'd you find it? Someday
I want to visit your library!
Didier Juges wrote:
Sorry, it's not 15nS rms, it's 15nS at 1 sigma.
Didier KO4BB
Didier
Surely the standard deviation (1 sigma) and the rms values are identical?
Specifying 1 sigma is perhaps intended to signify that the timing error
is stochastic.
Bruce
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Didier Juges wrote:
Sorry, it's not 15nS rms, it's 15nS at 1 sigma.
Didier KO4BB
Didier
Surely the standard deviation (1 sigma) and the rms values are identical?
Specifying 1 sigma is perhaps intended to signify
Hal Murray wrote:
You need to have a two stage register, allowing one clock period for
the first stage to come out of metastability. This of course delays
the signal to be synchronized by a clock period.
Yup. The delay is unavoidable. The only thing you can do is trade off delay
vs
Jason Rabel wrote:
I thought you had to use a VP in 6 channel mode for it to work on the
Z3801A?
Jason
If it uses the Motorola propietary commands, a M12 should be quite
compatible. I think a have somewhere some older documentation about the
@@ commands used in the 8-channel GPSs,
michael taylor wrote:
I was wondering if anyone knows any details, or has evaluated the
Trimble Mini-T, a cost effective GPSDO in a small board form factor.
http://www.trimble.com/minit.shtml
http://trl.trimble.com/dscgi/ds.py/Get/File-361589/022542-007_Mini-T_DS_0207_lr.pdf
The datasheet
Didier Juges wrote:
That would be fine if I were dealing with a Z3801, but at the moment, I
am looking at that Z3801 main board someone has been trying to sell on
eBay for the best part of a year and I was wondering if something could
be done with it. It has no GPS and no OCXO.
I have a
Didier
Didier Juges wrote:
Bruce,
Not knowing exactly what that entails, in spite of the volume of useful
information you and others have dispensed on this list on that subject,
but always the hopeful engineer that I am :-), I wholeheartedly agree
with you.
Another approach I am
jmfranke wrote:
Nope.
John WA4WDL
- Original Message -
From: Howard W. Ashcraft [EMAIL PROTECTED]
To: time-nuts@febo.com
Sent: Thursday, May 17, 2007 5:44 PM
Subject: [time-nuts] antenna length
Simple question.
I have a stock trimble thunderbolt that I am currently
Software correction of the sawtooth timing error of a GPS timing
receiver can be used to discipline an OCXO at a similar parts cost and
performance to the hardware sawtooth correction method.
The OCXO sinewave output is sampled by the leading edge of the PPS
signal and corrected for the
A small correction/clarification to the paragraph on the effect phase
detector gain error.
The input sinewave amplitude only has to be known to within a few (5%)
percent to keep the effective sawtooth correction error due to the phase
detector gain uncertainty under 1ns when using an M12+T or
Joseph Gray wrote:
I am running the Meinberg NTP software on two PCs. Both PCs are running
WinXP w/SP2, both are on the same network and both are syncing to servers at
pool.ntp.org. In the past, both clocks have shown that the two PCs had the
same time. Today, I just noticed that one of the
Joseph Gray wrote:
Are both machines syncing to the same ntp erver?
One or both of them of them hasn't synced to 127.127.1.0 by any chance?
Bruce
Although they are both using the pool at ntp.org, they are currently syncing
to different servers. They both are syncing to stratum 2
Tim Shoppa wrote:
Joseph Gray [EMAIL PROTECTED] wrote:
What are the actual IP addresses of the servers they are syncing to?
Bruce
The one with the correct time:
Sync to: 64.5.1.130 Offset: 38.346ms Stratum: 3
The one with the wrong time:
Sync to: 24.123.66.139 Offset: -1.074ms
Tom Van Baak wrote:
Define cheap.
You can already get essentially single chip TICs with a resolution (and
accuracy) better than 100ps for around 100 Euros or so.
Has anyone in the group tried one of these? I would very
much like to see the results.
All except Xavier seem to have
Tom Clark, K3IO wrote:
Bruce Griffiths wrote:
The Dallas delay lines aren't all that accurate, you need to calibrate
them to acheive 1ns accuracy (read the specs) and then you have to
worry about temperature variations.
To use them you need to decode the sawtooth correction message from
Tom
Tom Clark, K3IO wrote:
Why add the cost of a programmable delay line when the additional cost
of correction is a few lines of code?
They also don't remove the requirement for subnanosecond phase
measurement resolution and accuracy.
But the receiver itself has intrinsic noise at
: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Dr Bruce Griffiths
Sent: Saturday, May 12, 2007 7:00 AM
To: Tom Van Baak; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Software Sawtooth correction prerequisites?
Tom Van Baak wrote:
Define cheap
Tom Clark, K3IO wrote:
If you have a 10 MHz oscillator, simply feed it into the D
input into a latch clocked by the de-sawtoothed GPS 1PPS. The output of
the latch is a 0 or 1 depending on the precise phase of the oscillator.
You want this latched 0/1 measurement to average to ½ over a long
Jim Miller wrote:
My first post...newbie...be gentle...
I spent the last several evenings reading the archives and saw mention of
sawtooth error correction in software. Since the corrections to be applied
are on the order of 1e-9 seconds it would seem that the phase detector
outputs to
The statement that Dallas' version of the nanosecond differs by 10% from
Motorola's is somewhat disconcerting until one analyses how the delay
generator works.
Simplified description
Aside from the contribution from internal logic propagation delays
Delay = Constant*RC,
Where R is the value
Tom Van Baak wrote:
This sure sounds like a more complicated measurement than is necessary
to me. If you have a 10 MHz oscillator, simply feed it into the D
input into a latch clocked by the de-sawtoothed GPS 1PPS. The output of
the latch is a 0 or 1 depending on the precise phase of the
Jim Miller wrote:
My first post...newbie...be gentle...
I spent the last several evenings reading the archives and saw mention of
sawtooth error correction in software. Since the corrections to be applied
are on the order of 1e-9 seconds it would seem that the phase detector
outputs to
Javier wrote:
Tom Van Baak escribió:
When someone finds a cheap single-shot 1 ns TIC-on-a-chip
please let me know.
www.acam.de
Not very expensive although not cheap. I've some samples... but not yet
time to experiment with them.
Regards,
Javier, EA1CRB
Javier
You still
Javier
Corrected Analog TAC schematic attached.
The number of extra chips required depends on if one uses a CPLD or SSI
logic (eg 74HC/74AHC parts) and if your selected micro has a suitable
internal ADC and or a counter that can be sampled by an external signal
transition.
Bruce
inline:
Hal Murray wrote:
Synchronisers can easily be built from shift registers.
What do you mean by synchronizer?
Are you talking about a delay so the times line up correctly or a
circuit to avoid metastability?
Hal
Usually just a fast shift register with the number of stages
Bill Janssen wrote:
I thought that someone was designing a circuit that could be used to compare
two oscillators.
What happened to that project? I now have a HP 5370A so I have
something, but
I would like to make simultaneous measurements on three or four precision
clocks.I am not
Murray Greenman wrote:
TFers,
Further to Kit's post a week or two back, we've started to make some
ground regarding understanding and using these excellent little GPSDO
units. I have working DOS software, and they also work OK with SATSTAT.
I have also sussed the GPS module comms and written
Brian Kirby wrote:
Your a life saver. Can you confirm the pass transistor part number and
the regulator IC, looks like the 723 ?
Brian
Regulator is a 723, Transistor Q1 is a 2N3054.
Bruce
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[EMAIL PROTECTED] wrote:
In a message dated 4/29/2007 04:13:30 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Indeed. Three-four transistors and a handfull of caps and
resistors. The
Z3801A uses the 10 MHz clock and thus require a x1000
interpolation, which is
easy
Henk ten Pierick wrote:
On Apr 25, 2007, at 23:38, Dave Brown wrote:
Henk
Do any of the spurious signals show on the SA with a search antenna
(located in your lab environment)connected instead of the PRS10?
DaveB
No, they are not. I can see spurious if and only if the PRS10 is
[EMAIL PROTECTED] wrote:
Also, the PRS10 Stanford Rubiudium would have better than 1ns
resolution for time-tagging. I think they actually do resolve better
than 1ns, but don't use it.
bye,
Said
Said
The interpolator circuit resolution in the PRS10 time tagging circuitry
is about
[EMAIL PROTECTED] wrote:
Hi Bruce,
never doubted that it was technically possible to get this type of
resolution/accuracy. I myself mentioned the 15 year old Wavecrest units
achieve 800
femtoseconds resolution, single shot.
The point was
A) that type of resolution is not
[EMAIL PROTECTED] wrote:
C) I don't believe the Z3801A has 100ps single shot resolution and accuracy
(for resolution doesn't do anything without accuracy) until someone will
prove it to me. And even then it would be wasted resolution since the GPS
1PPS
source noise will totally swamp
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