Mike
It actually measures the additive phase noise of components
(amplifiers, splitters, transformers etc.).
Since it uses a cross correlation technique it can easily achieve a
noise floor below the thermal noise.
Cancellation of the carrier in the interferometer/bridge allows use of a
[EMAIL PROTECTED] wrote:
In a message dated 3/30/2007 16:02:15 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
It does in fact measure below the thermal noise floor.
This is not too difficult as it uses a crosscorrelation technique.
Bruce
Hi Bruce,
interesting how
Said
Actually I should have said -200dBc/Hz.
With a +13dBm carrier this corresponds to a noise voltage of 100pV/rtHz
across a 50 ohm resistor or a noise current of 2pA/rtHz flowing through it.
Even with a 1Hz noise bandwidth thats an rms fluctuation of about
12,500,000 electrons. You have
John Miles wrote:
Hi, Enrico --
I think a lot of us already tracked down your (excellent) site based on a
couple of links to your papers that were mentioned on the list earlier.
Thanks for making that content available! These days, it seems that half of
Google's search results on any given
[EMAIL PROTECTED] wrote:
In a message dated 3/30/2007 23:47:12 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Thermal noise and other noise in each channel are statistically
independent and their product averages to zero.
The actual residual decreases as the number of spectra
John Ackermann N8UR wrote:
John Miles said the following on 03/31/2007 03:16 PM:
Yep, that's the one. It used to be linked from his measuringphasenoise.htm
page but the link now points to something on his own f: drive, which is
sadly inaccessible to the rest of us...
Yes, a bunch
[EMAIL PROTECTED] wrote:
Hi Magnus,
BTW: here in the US they also like to measure things in fractions, and body
part lengths for some unexplainable reason... Reasons I do hear are that SI
is too difficult for the average Joe to comprehend, and replacing road
signs
costs too
Magnus Danielson wrote:
I'm considering putting that new and shiny audio analyzer to some alternative
use that I bought at work. Preferences towards BNC, XLR or Banana-jacks
anyone?
:)
I was just looking at the 3048 manuals the other night. Bumped into a new site
with HP manuals I haven't
John Ackermann N8UR wrote:
Dr Bruce Griffiths said the following on 03/31/2007 08:24 PM:
The second reason is somewhat spurious, other countries have converted
from the imperial to the metric system without major difficulty or
expense. It wasn't even necessary to change all road signs
[EMAIL PROTECTED] wrote:
Hi Bruce,
got it, thanks.
But isn't a signal source typically single-ended, and has a 50 Ohm source
impedance which creates noise?
Wouldn't we need a source with 1 Ohm source impedance even if the
measurement system is cross-correlated?
Would a
Magnus Danielson wrote:
In the article that was recently referred to, it was not a measurement rig for
oscillators but for transfer components, such as gain-stages, phase shifters
etc. and the approach is different then, since you do have the signal prior to
being dirtyfied. Thus, the
David Dameron wrote:
Hi all,
I just realized that a meter is defined by the speed of light., see
http://physics.nist.gov/cuu/Units/meter.html
It is only to 9 significant digits, so if the speed of light (in some
controlled environment) is measured more precisely than this, the meter and
all
David Dameron wrote:
Hi all,
I just realized that a meter is defined by the speed of light., see
http://physics.nist.gov/cuu/Units/meter.html
It is only to 9 significant digits, so if the speed of light (in some
controlled environment) is measured more precisely than this, the meter and
all
geo wrote:
Hi Jason,
perhaps i am the only german, currently available. My english is not good
but i hope, it's less pain for you to read my english than to read the
german text ;-)
Best regards
Martin Bertges
Description of Lucent RFTG-m-XO GPS frequency standard
ver. 20.03.2007
Palfreyman, Jim L wrote:
Are there actually US people on this list who actually continue to
advocate the use of non-metric units in their country? Speak up!
Well the USA ever go metric?
As an Australian, why would I care, you may ask?
Well because of the dominance of the US market, some
Bob Paddock wrote:
On Tuesday 03 April 2007 21:48, Dr Bruce Griffiths wrote:
An Australian Electronics magazine recently published a circuit for a
GPS disciplined crystal oscillator.
This particular implementation is the worst I've ever seen.
What would you consider the best you
Peter Vince wrote:
It's a shame the magazine article got it so wrong, but I can well
imagine how an enthusiastic amateur, without the collective knowledge
of our little group, might, with all good intentions, make such a
mess of the design.
I wonder if Bruce, or one of the other experts
[EMAIL PROTECTED] wrote:
In a message dated 4/7/2007 04:08:20 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
The Wavecrests are wonderful tools, but they address a different problem
than
what normal time-nuts usually care about, so they are not a given perfect
counter for long
Said
Some of the highest resolution techniques for comparing 2 10MHz sources are:
1) Use a Quartzlock A7-MX - resolution 5E-14/tau equivalent to 50 fs at
1 sec.
2) Use the JPL technique: Measure the beat frequency between the 2
oscillators (offset one oscillator by 1Hz using an offset
[EMAIL PROTECTED] wrote:
Hi Bruce,
My math is essentially their reference [4, p.26], and I did state that I
don't know the exact interpolator, trigger, and frequency-dependent noise
functions of the Wavecrest.
DTS-2075 is superior to the SR-620 and 53132A in time interval
[EMAIL PROTECTED] wrote:
Hi Bruce,
again, I did say in my original post that my math only works if their noise
is Gaussian, and that I did not know if it was.
Also, please note that they do claim 25ps Accuracy , and 800 femtoseconds
Hardware resolution, not the other way around.
[EMAIL PROTECTED] wrot
I am trying to set up a Win98 machine with GPIB since I bought a quite old
version of Visi from Wavecrest that runs only on Win98.
That's what usually happens with 16 bit Windows95/98 applications.
32 bit applications usually run on Win2K/XP/98 without difficulty.
[EMAIL PROTECTED] wrote:
In a message dated 4/8/2007 16:49:00 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Since Wavecrest, 53132A etc have no specifications for the effect of the
input circuit noise with a finite slew rate input, the only way to make
a more precise comparison
The attached table of logic gate propagation delay jitter should prove
somewhat challenging to verify with a time interval counter or similar
device.
In fact devising any method of verifying these figures will be somewhat
problematic.
However it could be done using by looking at the change in
David Andersen wrote:
Dr Bruce Griffiths wrote:
The attached table of logic gate propagation delay jitter should prove
somewhat challenging to verify with a time interval counter or similar
device.
In fact devising any method of verifying these figures will be somewhat
problematic
John Ackermann N8UR wrote:
John Ackermann N8UR said the following on 04/09/2007 08:40 AM:
I recently built 6 nominally 10 foot GPS antenna cables out of LMR-400.
They all had N connectors on one end, but the opposite ends were two
each of N, BNC, and TNC, which made measurement
Brooks Shera wrote:
In view of recent interest in the Allan Deviation of GPS-based 1 pps time,
it should be mentioned that the calculation of ADEV is based on a
statistical model which is not completely appropriate for noise sources
present in GPS signals and their decoding hardware/software.
Poul-Henning Kamp wrote:
In message [EMAIL PROTECTED], Brooks Shera writes:
The impact of time averaging to suppress white phase noise is illustrated
by a new plot TVB has created and placed on his website
http://www.leapsecond.com/pages/3gps/gps-adev.gif.
These revealing plots show
Ulrich Bangert wrote:
Bruce,
the following is part of a discussion in comp.arch.fpga:
.
Hi,
I would like to know what are the common methods of introducing
delays as low as 10ps between two outputs in an FPGA. I do
Enrico Rubiola wrote:
My friends, if you worry about jitter there is a trick:
synchronize the signat to the clock with a D-type flip flop,
just at the output.
Maybe too trivial for you.
E.
Enrico Rubiola
professor of electronics
web: http://rubiola.org
e-mail: [EMAIL PROTECTED]
Hal Murray wrote:
I would like to know what are the common methods of introducing
delays as low as 10ps between two outputs in an FPGA. I do not
I'd try to make the delays within the FPGA the same and then tweak the
external trace lengths. At that level of detail, you will have to
Hal Murray wrote:
[context is avoiding hanging bridges]
Ovenize it to control the sawtooth frequency?
Temperature controlled oscillator! :-)
Should be fairly simple to acheive, really just a FLL.
I was wondering about that a while ago. Is the basic idea feasible?
Assume you had
Magnus Danielson wrote:
From: Enrico Rubiola [EMAIL PROTECTED]
Subject: Re: [time-nuts] Gate propagation delay jitter
Date: Wed, 11 Apr 2007 00:14:01 +0200
Message-ID: [EMAIL PROTECTED]
Enrico,
Then we would need to know/measure the jitter of the retiming
flipflop.
Expected
[EMAIL PROTECTED] wrote:
In a message dated 4/10/2007 14:33:17 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Yes ground bounce can play havoc with the effective switching thresholds.
One would expect this effect to be much worse with single ended clocks.
Bruce
Hi Bruce,
[EMAIL PROTECTED] wrote:
In a message dated 4/10/2007 14:28:11 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Then we would need to know/measure the jitter of the retiming flipflop.
There appears to be little definitive published data on the jitter of
various logic gates and
Hal Murray wrote:
And Hal- what about the pcb layout for Bruce's 74CX version? Had time
to look at it yet?
It fell through the cracks when I got interested in something else.
Is anybody really interested in that board? If so, please send me a
reminder about the schematic.
There
VK3YV wrote:
Hi Bruce, I for one would like to get the completed circuit seeing as I
started the whole thing off and was just getting ready to maybe do a copy of
the HP unit.
Regards DonVK3YV.
Don
AD9901 version attached. It needs another opamp to be added to allow the
scale and
Hal Murray wrote:
Surely it would be much simpler (in principle at least) to just to add
sufficient Gaussian phase noise to the GPS receiver clock so that
potential coherence problems are virtually eliminated.
It doesn't look reasonable to me, but I'm not good at this sort of math.
Neon John wrote:
At that same altitude of looniness - waay out there - is the $50K
turntable where the works float on a pool of mercury contained in a
hollowed out lake on the top of about 2 tons of solid marble block. I
used to have the URL to this thing but I can't seem to find it.
Brooke Clarke wrote:
Hi:
I've heard that the aging rate of crystals gets better as the frequency gets
lower. The idea is that the more mass in the crystal the less an atom here
or
there will be missed. So the 32768 Hz watch crystals should be very good
compared to a 10 Mhz crystal.
michael taylor wrote:
I recently acquired a surplus Datum/Efratom LPRO-101 Rubidium
oscillator, found a PDF manual from Datum and was wondering if anyone
had any advice or warning on using these oscillators.
I was planning on building a GPS disciplined oscillator using the LPRO
and the 1 PPS
Hal Murray wrote:
There are plenty of times when sawtooth removal would be of use/
interest, but in a typical GPSDO which has a heap of other errors, I
do wonder what improvements in performance would actually be seen in
the output from the oscillator - which is all that a lot of people are
John Ackermann N8UR wrote:
There is a firmware image for the Reflock II that will lock a 10 MHz (or
other relatively-low-frequency) oscillator to PPS. The last time I
looked at it, it worked OK but not up to a real GPSDO -- which makes
sense since it's a pretty basic PLL. Luis Cupido has
John Miles wrote:
One solution: double the 10 MHz twice to get 40 MHz, divide by 5 with any
handy 74HC or 74F counter to get 8 MHz, and mix that with the 40 MHz signal
to get 32 MHz and 48 MHz. Basic LC filtering should be adequate in the
10-40 MHz multiplier and the 32 MHz output sections.
Neville Michie wrote:
Hi All,
another method that avoids PLL and other sources of phase noise is to
divide down to 2MHz, get a square wave signal,
low pass it to make a rough sine wave, feed it into a full wave
rectifier, (pair of diodes) and the fundamental is eliminated and
Tom Van Baak wrote:
Bruce, I'm getting the idea you don't like _any_ of the
hobbyists GPSDO's that have come out in the last ten
years...
So I'm curious what then would qualify as a well designed
GPSDO in your opinion? (and please don't bring up the
Quartzlock thing; it's a hundred times
Rasputin Novgorod wrote:
Hmm. ...and I just bought a set of three Chef's knives for my
kitchen for $500.
/b
--- Jack Hudler [EMAIL PROTECTED] wrote:
Just please tell me they're not serrated, know how to use a steel,
and you keep them holder or leather pouch.
Hi Jack:
Dr Bruce Griffiths wrote:
Tom Van Baak wrote:
Bruce, I'm getting the idea you don't like _any_ of the
hobbyists GPSDO's that have come out in the last ten
years...
So I'm curious what then would qualify as a well designed
GPSDO in your opinion? (and please don't bring up the
Quartzlock
Howard W. Ashcraft wrote:
I have been building a GPSDO around an HP10544A that I purchased on
eBay. After some teeth-gnashing, I have concluded that the 10544A is
defective. When attached to a load (it is supposed to be rated into 50
ohms) the frequency drops radically, and in fact, the
Peter Vince wrote:
Hello all,
The recent talk about the ideal GPSDO has reminded this newbie of a
question I hope someone might be able to simply answer: we have a couple
of Rubidium GPSDOs which track in the long term, but their phase drifts
by several hundreds of nanoseconds with an
Said
[EMAIL PROTECTED] wrote:
Hi Henk,
I have a expensive 10MHz ultra-low-noise Wenzel oscillator that we bought
some months ago that has similar very nasty noise on it's output.
See the attached HP8563E plot, you can see the worst spur at 280MHz at
-56dBm, which is about
Said
[EMAIL PROTECTED] wrote:
Spurs cause nasty deterministic jitter of course.
Only if the spurs are not harmonics.
Bruce
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Peter
A more prosaic explanation springs to mind.
What are the specs for the Disciplined oscillator package?
It is possible that the frequency setting resolution is a few times
1E-11 and the frequency steps you see correspond to 1-2 bits of the
frequency setting DAC.
Bruce
[EMAIL PROTECTED] wrote:
I'm also interested in the same thing. Not sure how much they cost but I did
a google for VCXO and you can have one made for 32 Mhz. Should be able to
use similar devices that discipline a 10 mhz osc to discipline a 32 Mhz osc
from a GPS engine or a 10 Mhz
Bob Paddock wrote:
On Monday 23 April 2007 03:56, Don Collie wrote:
The thing that puzzles me is: why is the plot of
VCO voltage versus time different when locking from below to locking from
the same initial frequency difference when locking from above. It`s a pity
you can`t predict
Tom
Attached images are drift plots for:
1) VRE430 reference utilising a buried zener.
2) LM199
3) LTZ1000
Bruce
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Question - does Vref drift matter for a GPSDO? It seems it is
either too low to be of concern or the effect of Vref drift is in
fact indistinguishable from OCXO frequency drift and is thus
transparently compensated by any 3rd order loop?
I don't know for sure, but is 1 ppm/day drift in Vref
Tom Van Baak wrote:
Can someone do a similar numerical analysis of these two
factors: tempco and noise? It's not that I don't believe you;
it's just that I'd rather see numbers and plots than words.
Tom
When the reference is temperature cycled hysteresis may be significant.
Hysteresis
Tom
Attached is some hysteresis and other data for various references.
NB take the claimed XFTE reference ADR293 drift figure with a large dose
of salt, its 2 orders of magnitude lower than ADI claim.
Bruce
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Tom Van Baak wrote:
Also an idea - is there an easy way to artificially increase Vref
noise, by say 10x, so one could see if that change made any
measurable change in OCXO output ADEV or phase noise?
/tvb
Tom
1) Increase the cutoff frequency of any low pass filter used.
2) With a
Tom Van Baak wrote:
Also an idea - is there an easy way to artificially increase Vref
noise, by say 10x, so one could see if that change made any
measurable change in OCXO output ADEV or phase noise?
/tvb
Tom
Another possibility is to use a low noise instrumentation amplifier with
a
Palfreyman, Jim L wrote:
Folks,
The longest antenna I have for my GPSDO is 5m (it's a Trimble ACE III
inside). Is it possible to lengthen this just by adding an extension
cable (SMB female on one end and SMB male on the other)? I'd be
interested in adding another 5m.
I've not been able to
Brooke Clarke wrote:
Hi Henk:
Here is a spectrum plot from my PRS10. But it's also connected to the
SR620 so I'm not sure where the spurs are coming from.
Have Fun,
Brooke Clarke
Brooke
60Hz spur - mains related?
70Hz spur from internal phase modulation frequency used in PRS10?
Bruce
Brooke Clarke wrote:
Hi:
Sorry. That was a phase plot in the same folder on my computer.
Here's my spectrum plot.
Have Fun,
Brooke
http://www.PRC68.com
http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
Brooke
The 15MHz, 25MHz and 35MHz spurs are
[EMAIL PROTECTED] wrote:
They can get 0.1ns resolution on the printout because of averaging. I don't
know what their native granularity is.
Single shot resolution may not have such a significant impact since the GPS
used in the Z3801A is so much worse than the M12+.
Our resolution
[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
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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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
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
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
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
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
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
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
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
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
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
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