A separate thread on this topic is probably warranted.
References:
Current performance:
http://tf.boulder.nist.gov/general/pdf/1219.pdf
Comparison of CPT and IOP:
http://www.kernco.com/pdfs/TransIM03.pdf
older papers illustrating techniques required:
/Session_11_Microwave_Clocks/11_02_Affolderbach.pdf
http://infoscience.epfl.ch/record/170602/files/EFTF2012_Bandi_v2.pdf
http://infoscience.epfl.ch/record/178228/files/IFCS_Invited_Talk_Finalpdf.pdf
Bruce
Bruce Griffiths wrote:
A separate thread on this topic is probably warranted.
References:
Current
Since performance improves as the bandwidth of the lamp spectrum
decreases its not unreasonble to suggest that a suitable laser source
may improve performance further.
The following paper (and theoretical considerations) indicate that your
conclusions regarding the potential performance of a
Attila Kinali wrote:
On Sun, 28 Apr 2013 17:50:06 +1200
Bruce Griffithsbruce.griffi...@xtra.co.nz wrote:
Has anyone considered a laser pumped variant like:
http://tf.nist.gov/general/pdf/1009.pdf
Apart from the ECDL laser (can be assembled using readily availalble
parts) it looks fairly
Has anyone considered a laser pumped variant like:
http://tf.nist.gov/general/pdf/1009.pdf
Apart from the ECDL laser (can be assembled using readily availalble
parts) it looks fairly straightforward.
Bruce
Tom Van Baak wrote:
Very nice bit of RD work on Corby's part. Mine is certainly
Attila Kinali wrote:
On Fri, 5 Apr 2013 23:18:49 -0600 (MDT)
Don Lathamd...@montana.com wrote:
Actually, mumetal easily loses permeability, hence shielding ability,
by mechanical stress or heat. Some mumetals are made to bend for boxes
and the like, sheets available from electronics
Attila Kinali wrote:
On Mon, 01 Apr 2013 09:08:51 +1300
Bruce Griffithsbruce.griffi...@xtra.co.nz wrote:
Nothing to do with laser line width.
Merely indicating that the photodiode mixer can be used with a suitable
LO to build an optical spectrum analyser front end.
Are you refering
Attila Kinali wrote:
On Mon, 01 Apr 2013 22:32:11 +1300
Bruce Griffithsbruce.griffi...@xtra.co.nz wrote:
Attila Kinali wrote:
On Mon, 01 Apr 2013 09:08:51 +1300
Bruce Griffithsbruce.griffi...@xtra.co.nz wrote:
Nothing to do with laser line width.
Merely indicating that
Nothing to do with laser line width.
Merely indicating that the photodiode mixer can be used with a suitable
LO to build an optical spectrum analyser front end.
Bruce
Attila Kinali wrote:
Moin,
On Sun, 31 Mar 2013 12:28:59 +1300
Bruce Griffithsbruce.griffi...@xtra.co.nz wrote:
With a
A photodiode is in fact a nonlinear device for optical fields as it is
essentially a linear optical power detector.
The output is proportional to the incident optical power not the field
amplitude.
Photomixers are routinely used in wide range of diverse application such
as translating the
slow detectors to see it, or mixing in nonlinear optical
materials.
Ed
Bruce Griffiths wrote:
A photodiode is in fact a nonlinear device for optical fields as it is
essentially a linear optical power detector.
The output is proportional to the incident optical power not the field
amplitude
with the optical carrier frequency. I was also picturing
wavelength/spatial separation with interference in order to allow
relatively slow detectors to see it, or mixing in nonlinear optical
materials.
Ed
Bruce Griffiths wrote:
A photodiode is in fact a nonlinear device for optical fields
The lack of synchronisers when crossing clock domains is a design flaw
that should be corrected.
Bruce
ewkeh...@aol.com wrote:
Brooks GPSDO may be 15 years old but is still perfect for today's
applications. If you look at tvb's Tbolt plot or Ulrich's plots with and without
sawtooth correction
There are essentially 4 clock domains in the circuit
1) PPS
2) Divided down 10MHz (~300kHz)
3) 24 MHz
4) The microprocessor internal clock ( the micro probably has internal
synchronisers for at least some external inputs).
Depending on internal delays and jitter this may be regarded as
Both edges of the 24MHz clock gating pulse are asynchronous with respect
to the signal being gated.
Metastability can result with clock pulse widths that lie within a
critical range.
Bruce
Chris Albertson wrote:
On Mon, Mar 25, 2013 at 12:45 PM, David McGawn1...@alum.dartmouth.org wrote:
Tom Van Baak wrote:
Both edges of the 24MHz clock gating pulse are asynchronous with respect
to the signal being gated.
Metastability can result with clock pulse widths that lie within a
critical range.
Bruce
I don't disagree with your statement above, but my question was -- does it
Richard H McCorkle wrote:
Hi Tom,
In the Shera design the instability of the XO timebase is
a key factor in improving the 30-second update resolution.
With the XO drift varying the sample point across the 1PPS
and 312.5 KHz edges the samples are constantly varying and
the average of the samples
Switch mode power supply ?
FLL or PLL loop?
Bruce
Magnus Danielson wrote:
Fellow time-nuts,
I got the oppertunity to measure a cesium with my TimePod, I hooked up
on the FS 730/1 and noticed a bump in the phase-noise. I by-passed it
and the bump was not there. Turns out that it had a 20 dB
/22/2013 10:01 PM, Bruce Griffiths wrote:
Switch mode power supply ?
FLL or PLL loop?
Bruce
Magnus Danielson wrote:
Fellow time-nuts,
I got the oppertunity to measure a cesium with my TimePod, I hooked up
on the FS 730/1 and noticed a bump in the phase-noise. I by-passed it
and the bump
Ulrich Bangert wrote:
Gentlemen,
although it has been discussed here by Bruce et al how the noise floor of
integrated distribution amplifiers designs may compare to discrete designs I
have never seen a *real* phase noise measurement of a *real* amplifier here.
My own measurements on a DIY
Not quite, the contribution to AD of a gaussian jitter source is SQRT(6)
times the rms jitter.
Bruce
Ulrich Bangert wrote:
Mark,
given the fact that the measurement results of a 5370 are integer multiples
of 20 ps it is absolutely natural to see these steps in a phase plot, at
least if the
Poul-Henning Kamp wrote:
Content-Type: text/plain; charset=ISO-8859-1
In messagebay162-w38a3ac22812ac79a0fbfc6df...@phx.gbl, Tom Knox writes:
Starting with a hp supply this finesse regulator will really clean
up the output. http://www.wenzel.com/documents/finesse.html
I've
Lester Veenstra wrote:
The typical test supply on a bench for clean VCO testing is a small gel cell
battery. For a regulated power supply, make one using a 723. The 723 has
far lower noise out than the monolithic regulators.
Depends on the variety of 723 some are noisier than others.
Some
Poul-Henning Kamp wrote:
Content-Type: text/plain; charset=ISO-8859-1
In message7cc93b1acc5743a3b5536dbf798b7...@vectron.com, Bob Camp writes:
There's a paper in the February IEEE UFFC transactions proposing that the SI
standard of mass be replaced with a 1 KG quartz resonator.
is
that a quartz resonator could be monitored for change to a much tighter
level than that.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bruce Griffiths
Sent: Tuesday, January 22, 2013 2:39 PM
To: Discussion of precise time and frequency
Hal Murray wrote:
albertson.ch...@gmail.com said:
The Heliax will only do good if the length of the run is long.
I don't understand that. What does the type of antenna have to do with the
length of the run?
Do Heliax antennas have a couple of dB gain over other antennas? I can
No the noise in the upper and lower sidebands are correlated
Thus the DSB PN is 6dB greater than the SSB PN.
Bruce
Graham / KE9H wrote:
Bruce:
The last time I looked, the thermal noise floor was still -174 dBm/Hz
(at 300 Kelvin).
http://en.wikipedia.org/wiki/Thermal_noise
Are you saying
Graham / KE9H wrote:
Bruce:
The last time I looked, the thermal noise floor was still -174 dBm/Hz
(at 300 Kelvin).
http://en.wikipedia.org/wiki/Thermal_noise
Are you saying Boltzmann's constant is off by 3 dB, or are we mixing
apples and oranges here?
Is there a 3 dB adjustment between
I've noticed a disturbing tendency to quote the thermal noise
contribution to phase noise as -174dBm/Hz instead of the corrent value
of -177dBm/Hz as verified by measurement by NIST:
http://tf.nist.gov/phase/noisemeas.html
This error occurs in papers from Spectrum Microwave, Wenzel Associates
the noise, since it only looks on one side of the reference signal?
--- Graham / KE9H
==
On 1/15/2013 1:38 PM, Bruce Griffiths wrote:
I've noticed a disturbing tendency to quote the thermal noise
contribution to phase noise as -174dBm/Hz instead of the corrent
value of -177dBm/Hz as verified
so their combined power level
is 6dB higher when translated to baseband as is done in a traditional
analog diode mixer based phase noise measurement system.
Bruce
--- Graham / KE9H
==
On 1/15/2013 1:38 PM, Bruce Griffiths wrote:
I've noticed a disturbing tendency to quote the thermal
The thermal contribution to SSB phase noise power is -177dBm/Hz.
For a carrier level of 0dBm the corresponding SSB phase noise is -177dBc/Hz.
Its even possible to measure the residual phase noise of components
where the component phase noise is below the phase noise due to thermal
noise.
PN
Attila Kinali wrote:
On Sun, 23 Dec 2012 22:45:40 +0100
Fabio Ebolifabi...@quipo.it wrote:
Il 2012-12-23 07:42 Bruce Griffiths ha scritto:
The classic TAC using current mode switching is similar to the
attached circuit schematic.
http://pastebin.com/EkgqmgfE
I have
Since injection locking is possible when the ratio of the 2 frequencies
involved is a rational number, a 16 MHz oscillator can be directly
injection locked to a 10MHz signal without the need for dividers etc.
Bruce
paul swed wrote:
Tom.
OK the challenge simple. CD4046 16 MHz vco and div by 8
. There
were some articles that the spread spectrum hams used that describe it.
On Wed, Jan 2, 2013 at 2:48 PM, Bruce Griffiths
bruce.griffi...@xtra.co.nzwrote:
Since injection locking is possible when the ratio of the 2 frequencies
involved is a rational number, a 16 MHz oscillator can be directly
Tom Knox wrote:
Dual oscillators in Cross Correlated
measurements will also produce a 3dB theoretical reduction in a Phase
Noise measurement system.
Since when?
Its way better than that.
I routinely achieve a PN floor below -170dBc/Hz (I don't have an OCXO
with a phase noise floor below ~
Robert Atkinson wrote:
Hi,
While it may be a waste of time and money for time nuts, it may be a good
introduction for others. It may even spawn a few time nuts. Better someone
build this and learn something than just buy a cheap Chinese counter on ebay.
I've seen much worse projects
.
Only the phase noise that is common to both measurement channels
remains after sufficient averaging.
Average in the power summer? Taking hundreds or thousands
oscillators it seems possible to reach astonishing levels...
Bruce
On Sun, Dec 30, 2012 at 10:44 AM, Bruce Griffiths
bruce.griffi
Fabio Eboli wrote:
Hello
How could I test the time to analog converter
we talked few posts ago?
Something that can be done with things I have
or can easily find.
One method is to use a statistical fill the buckets technique to measure
the linearity.
To do this one needs to use an incoherent
One potential source of non monotonicity is the ADC particularly those
embedded in a microprocessor.
The only cure being to either use an external ADC that is monotonic or
truncate the ADC result until it's monotonic.
Varying the synchroniser clock frequency (a 2:1 range should suffice to
Fabio Eboli wrote:
Bruce, Bob, now I have more questions
than before :)
First and most important:
Where can I find references about the
statistical method you mentioned?
I tried to search online but didnt't find
any info.
Fabio Eboli wrote:
Bruce, Bob, now I have more questions
than before :)
Fabio.
P.S. The micro's adc is charachterized
for total unadjusted error of +-2LSB Max
at 25°C, 12bit total.
It's s-h is 8pF with 1kohm in series,
probably I can sync the sampling to
open just before the pulse, and close
Tom Harris wrote:
Watch out for Silicon Chip designs, they have a habit of not making the
source code available, which you only find out at the end of the project. I
suppose that it is to allow the author to make a few extra $$ selling
programmed micros. They had a nice 3 phase inverter design a
Fabio Eboli wrote:
Hello, hope you all had a happy Christmas.
Back to the topic.
Bob Camp asked:
Hi
One very simple question - how good would it do if you just did it
all with logic gates? Tri-state buffers and things like that….
Now that you are up to a 100 to 200 ns long pulse, a lot of the
Fabio
The simplest (lowest part count and least number of power supplies)
consists of a tristate buffer driving an RC circuit.
The PPS signal is connected directly to the buffer input whilst the
output of the PPS synchroniser (at least 2 stages to minimise the
probability of metastabilty at
Fabio Eboli wrote:
Il 2012-12-23 07:42 Bruce Griffiths ha scritto:
The classic TAC using current mode switching is similar to the
attached circuit schematic.
Bruce I tried to replicate the circuit
you attached, the pic was low resolution
so I tried to figure the values.
This is the circuit
Fabio Eboli wrote:
Il 2012-12-23 11:36 Bruce Griffiths ha scritto:
The simulation indicates that the TAC capacitor charging current is
far from constant whilst charging.
This is due to the use of saturated switches rather than current
steering switches.
The capacitor charging current is poorly
Fabio Eboli wrote:
Hello, Bruce
Using saturated transistors as switches in the current source and
elsewhere isn't conducive to fast switching.
The traditional arrangement using current mode switches is much
faster and more predictable.
This is something I'd like to understand better.
I'm
Magnus Danielson wrote:
Dear Fabio,
On 12/22/2012 02:34 PM, fabi...@quipo.it wrote:
I answer here to Bob Bill and Magnus.
Hi
I think I would grab some sort of USB thermometer and start logging
the room temperature.
CMOS input op-amps are a pretty good way to buffer the integrating
capacitor.
Its actually a relatively low performance implementation of a classic
technique.
The ramp capacitor reset switch (a saturated transistor) has a
relatively slow turnoff and poorly defined reset voltage.
For shorter time delays lower capacitance current source and reset
devices are required.
Hal Murray wrote:
jim...@earthlink.net said:
You mean RG65 http://www.awcwire.com/ProductSpec.aspx?id=M17/
34-RG65-Coaxial-Cable or RG186 http://www.awcwire.com/ProductSpec.aspx?id=RG1
86-Coaxial-Cable
Interesting stuff. Thanks.
RG-65 says no longer available. It also says:
Ulrich Bangert wrote:
Gentlemen,
I own a dead HP34401. On switching it on the display stays dark. It will
however react on pressing the SHIFT key.
By changing pcbs against a working one the display board has shown to be ok.
There must be a problem with the main board. Without knowing whats
paul swed wrote:
Two comments the manuals available on agilent
What on earth is a crossguard?
Crossguard comms (Agilents term) refers to the optoisolators used for
serial communication between the floating and earth referenced logic
sections.
Bruce
It only resets the earth referenced micro (8051) on power up and when
pulses on the optocoupler output arent present.
There is no other connection to the reset pin of this micro.
The floating logic is reset by the LM2925 5V regulator reset output.
There is no connection to this reset line aprt
Magnus Danielson wrote:
On 12/11/2012 11:50 PM, Azelio Boriani wrote:
I think that the TBolt's schematic(s) are sort of HolyGrail for
TimeNuts.
They are pretty simple, so I am amazed that there has been no major
attempt to reverse engineer them. The GPS front-end chip I haven't
been able to
Hal Murray wrote:
albertson.ch...@gmail.com said:
What is the simplest phase detecter that could work? I think only that, and
then a duouble oven crystal from eBay, a GPS and and Arduido.
You also need a good D2A to drive the EFC on the osc.
A synchronous filter of a suitably
A low noise sample and hold is still required.
Bruce
Bob Camp wrote:
Hi
Does the synchronous filter on the PWM still have a sample and hold in it, or
has somebody come up with a different approach?
Bob
On Dec 5, 2012, at 3:06 AM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote:
Hal
The lasers arent that difficult to make or expensive if one adopts a
modified Littrow ECDL configuration.
Laser diodes without AR coatings have been used successfully in such lasers.
Low noise current sources and close temperature control of the laser
diode chip are required.
Bruce
paul swed
Support HpW-Works.com wrote:
Hi Bruce,
The equivalent phase noise (measured in dBc/Hz) is essentially independent of
the sample size.
The dBc/Hz normalization is based on this (also the sample rate). While the
sample
rate sample size = FFT Bin size (resolution or filter band
Demian Martin wrote:
I asked Wenzel about mixers for phase noise measurement and they directed me
to Marki Microwave as what they use:
http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or
tested any myself but it's a pretty solid recommendation I think.
I got this guy to add
Adrian wrote:
Bruce Griffiths schrieb:
Demian Martin wrote:
I asked Wenzel about mixers for phase noise measurement and they
directed me
to Marki Microwave as what they use:
http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or
tested any myself but it's a pretty solid
Adrian wrote:
Bruce Griffiths schrieb:
Adrian wrote:
Bruce Griffiths schrieb:
Demian Martin wrote:
I asked Wenzel about mixers for phase noise measurement and they
directed me
to Marki Microwave as what they use:
http://www.markimicrowave.com/2770/Mixers.aspx I have not
obtained
Support HpW-Works.com wrote:
Bruce,
There's no evidence of a cross power spectrum function in this suite.
One needs to be able to average at least 10,000 cross power spectra for some
applications.
In the PSD (power density) PSP (power spectrum) there are cross power and
cross
Richard (Rick) Karlquist wrote:
On 11/23/2012 9:38 AM, Bruce Griffiths wrote:
NIST have shown (at least at 10MHz) that the high level mixers they
tested are noisier than the ZRPD1.
Bruce
Do you have a citation to where they said that?
What you quoted doesn't make sense, at least, out
Rick Karlquist wrote:
Bruce Griffiths wrote:
Richard (Rick) Karlquist wrote:
On 11/23/2012 9:38 AM, Bruce Griffiths wrote:
NIST have shown (at least at 10MHz) that the high level mixers they
tested are noisier than the ZRPD1.
Bruce
http
NIST have shown (at least at 10MHz) that the high level mixers they
tested are noisier than the ZRPD1.
Bruce
Alan Melia wrote:
Hi Anders, isn't this format exactly what is inside the high level
mixers (spec'e +17dBm) from Minicircuits?
Alan
G3NYK
- Original Message - From: Anders
Magnus Danielson wrote:
Hi Anders,
On 11/23/2012 04:42 PM, Anders Time wrote:
I have been using an minicircuits mixer as a phase detector for
measuring
low frequency(5-10MHz) and it is usually good enough. But when I want to
measure 100MHz the sensitivity of the mixer decreases a lot, so when
combination isolation amplifiers may not be necessary.
Bruce
Bruce Griffiths wrote:
Since mixer noise is one of the limiting factors using a mixer with low flicker
noise will help.
NIST found that a custom mixer using diode connected (collector base short)
2N222As had
Its actually Tau with a subscript 0.
This is the the time interval between successive measurements.
e.g. if a measurement is taken every second then Tau0 is 1 sec.
Bruce
Edgardo Molina wrote:
Dear John Ackermann,
I find your reply to my request to be very interesting. Without fear of asking.
ewkeh...@aol.com wrote:
The D/M is being revisited because of the counter performance. 1 E-13 is
easily attainable but the Czech IREE published a paper and claim 2 E-15.
Do you mean the paper optimization of dual-mixer time-difference
multiplier ?
The ZCD developed in this is a bit of a
Since mixer noise is one of the limiting factors using a mixer with low
flicker noise will help.
NIST found that a custom mixer using diode connected (collector base
short) 2N222As had a significantly lower flicker phase noise than either
the ZRPD1 or the 10534A.
They used off the shelf 1:5
for a 2x ZRPD1 +
Splitter combination isolation amplifiers may not be necessary.
Bruce
Bruce Griffiths wrote:
Since mixer noise is one of the limiting factors using a mixer with
low flicker noise will help.
NIST found that a custom mixer using diode connected (collector base
short) 2N222As
-2-1).
The ZRPD1 has an RF1 - RF2 isolation of around 70dB at 10MHz.
With a channel to channel isolation of around 110dB for a 2x ZRPD1 + Splitter
combination isolation amplifiers may not be necessary.
Bruce
Bruce Griffiths wrote:
Since mixer noise is one of the limiting factors using
of around 70dB at 10MHz.
With a channel to channel isolation of around 110dB for a 2x ZRPD1 + Splitter
combination isolation amplifiers may not be necessary.
Bruce
Bruce Griffiths wrote:
Since mixer noise is one of the limiting factors using a mixer with low flicker
noise
A 50% duty cycle square wave with an amplitude 5V pp should be OK.
Bruce
Edgardo Molina wrote:
Dear Group,
Does anybody know is the TAPR TADD-2 Mini works with input signals with square
wave geometry? Or Sine wave only?
Thank you.
Regards,
Edgardo Molina
Dirección IPTEL
That should be OK connected directly to the input as the resultant
reverse bias on the switching transistor base-emitter junctions is well
within the specified limits
One can check this both by simulating the performance and by actual
measurement with a scope.
Bruce
Edgardo Molina wrote:
For those that have Timelab the link to the E1938A PN measurement data is:
https://dl.dropbox.com/u/59708595/E1938A.tim
Bruce
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
Magnus Danielson wrote:
On 09/29/2012 02:45 PM, Bruce Griffiths wrote:
For those that have Timelab the link to the E1938A PN measurement
data is:
https://dl.dropbox.com/u/59708595/E1938A.tim
Thank you. I will measure mine so that we can compare them.
Cross-correlation with a pair of BVAs
Ulrich Bangert wrote:
Gentlemen,
I know that lots of you own a GPSDO, some of you two or even more. For that
reason I conclude that there must be a lot of knowledge available on how
different GPSDOs perform against each other. This is why I want to put
forward the question for the BEST GPSDO in
Hal Murray wrote:
d...@montana.com said:
Michael: Actually implementing a 16 bit DAC to its 1-bit minimum resolution
will be headache enough. You will gain a real education in good grounding
practice, shielding, power supply stability and noise, and other Murphy
intrusion. A 32 bit DAC
Azelio Boriani wrote:
Also you need a super ultra fantastic voltage reference for a 32bit DAC.
Not really, the reference only needs to have low noise and good short
term stability.
Long term drift in the reference voltage will be corrected by the
feedback loop.
Anyway, yes, in my GPSDO
Jim Lux wrote:
On 9/9/12 9:37 PM, li...@lazygranch.com wrote:
What am I missing here? Vce = Vbe, so the diode connected transistor
isn't saturated.
I think it's where the diode is fully conducting, and into the linear
part of the V/I curve, not in the square law part any more.
In normal
For this particular application a capacitive termination (NIST used such
a termination in their DMTDs) of the IF port followed by a low pass
filter is advantageous.
For precision work screw connectors (SMA, TNC, N etc) are more stable
than bayonet connectors like the BNC.
Bruce
J. Forster
David Kirkby wrote:
On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote:
Hello Brian,
I am a radio amateur and and also in the Time nuts list, At the
moment I am planning to bild a DMTD for experimentation. and as you have a nice
experience
NIST have indicated that mixer PN noise measurements with a non
dissipative terminations (even RF) are intended to be made.
Using a discrete mixer using diode connected transistors may also be
useful at least for 5MHz and 10MHz input frequencies in that their
flicker noise can be
Not transistor saturation but mixer saturation where the RF input is
sufficiently that for a given LO level the IF output level is saturated
(ie doesnt increase (or increases very slowly) with increasing RF signal
level).
Bruce
li...@lazygranch.com wrote:
What am I missing here? Vce = Vbe,
at Agilent pointed me to this paper
entitled
The Design of Low Jitter Hard Limiters by Oliver Collins. In
Bruce Griffiths' precision time in frequency webpage, this paper is
described
as
seminal.
(http://www.ko4bb.com/~bruce/ZeroCrossingDetectors.html)
Since I'm
Chris Wilson wrote:
13/08/2012 22:18
David Partridge was able to supply one of his last remaining frequency
dividers to me, for use with my TB GPS standard. It works perfectly
and is now in a nice enclosure feeding a small array of BNC sockets on my
shack wall. My question is, if I take the
John Ackermann N8UR wrote:
Magnus inspired me to try my own cross-correlation experiment with the
TimePod today. I used two fairly normal OCXO frequency standards as
the reference, and a Wenzel 5 MHz ULN as the device under test.
By doing single-reference measurements of each OCXO versus the
The problem of optimal zero crossing detector design was essentially
solved by Oliver Collins in the 1990's.
Essentially a series of cascaded limiter stages with appropriate gain
and bandwidth distribution are used.
With a 10MHz 1V rms signal only 2-3 stages suffices.
However unless you need fs
Chuck Forsberg WA7KGX N2469R wrote:
OK, what are the differences between
37265
34310
49422
The 32765 is in one of my thunderbolts.
I replaced the failed OCXO in another Thunderbolt with the 49422.
The 49422 has a different pinout, is taller, and has opposite gain.
Is there a difference in
cell
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bruce Griffiths
Sent: Monday, May 28, 2012 1:44 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] DDS in GPSDO design?
Since the Taylor series
Poul-Henning Kamp wrote:
In message4fc2a5e9.7050...@partiallystapled.com, Michael Tharp writes:
Does anyone have any comments or experience with DDS-based frequency
references?
I belive that is basically how the optional output generator works for
hydrogen masers.
The
Michael Tharp wrote:
Greetings,
I've been pondering topologies for a custom GPSDO design and two
obvious choices seem to present themselves. The first, and seemingly
more popular by far, is to use a pullable oscillator as many OCXO
and Rb oscillators are and discipline it using a slow but
The keyword is good most commercial DDS chips aren't (at least when used
directly for a fine offset generator ).
The Symmetricom TSC5120A phase noise test set implements the DDS in an
FPGA wherein which its possible to virtually avoid the phase truncation
errors produced by commercial DDS
Michael Tharp wrote:
On 05/27/2012 06:23 PM, Bruce Griffiths wrote:
The principal problem with conventional DDS implementations is phase
truncation spurs which can occur close to the desired carrier.
Virtually all commercial DDS chips produce such phase truncation spurs.
It is possible
Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bruce Griffiths
Sent: Monday, May 28, 2012 12:10 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] DDS in GPSDO design?
Michael Tharp wrote:
On 05/27/2012 06:23 PM
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bruce Griffiths
Sent: Monday, May 28, 2012 12:10 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] DDS in GPSDO design?
Michael Tharp wrote:
On 05/27/2012 06
Of Bruce Griffiths
Sent: Monday, May 28, 2012 12:36 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] DDS in GPSDO design?
These Xilinx datasheets indicate the performance of some techniques:
http://www.xilinx.com/support/documentation/ip_documentation
Mark Sims wrote:
It appears to be the same as the other one (which has an unreadable label).
This one is marked Trimble 0001-262T 34310-T2.
So far it appears to be oblivious to external temperature changes. I don't
know about its phase noise. The other unit had been running 24/7 for
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