It won't be state of the art (I think tvb's cesium wrist watch does that..
but it doesn't have the non-digital display you want)
One would think wristwatches based on the Symmetricom CSAC would be on
the market by now.
http://leapsecond.com/images/tvb-csac.jpg
/tvb
In message 1225454799-1347767280-cardhu_decombobulator_blackberry.rim.net-1901
834519-@b27.c1.bise6.blackberry, li...@lazygranch.com writes:
The PWM DAC should have perfect differential linearity, which I
believe is all that matters in this application. (That and no missing
codes.) Not so when
In message 5C1BBD844F6145969FE8A4785FEE490A@pc52, Tom Van Baak writes:
Has anyone on the list done work optimizing the timing accuracy rather than
the frequency stability?
Yes, timing accuracy has been my main focus and in general I have been
using integration times on the low side of 1
Yes, timing accuracy has been my main focus and in general I have been
using integration times on the low side of 1 seconds for that,
but it depends a lot on the OCXO/Rb and environment.
The PLL in NTPns is a (by now) old attempt to make a self-tuning PLL
for optimal time stability, and
Hi
If your definition of timing accuracy is within 100 ns of GPS time ten minutes
after lock then a faster crossover is a better idea. A faster loop will track
GPS better. If your GPS noise is on the order of 10 ns, your time error will
be pretty low. An example: 100s loop and 10 ns GPS, =
On 9/15/2012 2:11 PM, paul swed wrote:
Then respond back with whatever the response might be and then simply pass
through in both direction whatever comes next.
Could an updated rcvr be used.
Is this init command really the only gotcha?
It's more than just the init command. The z3801a also
Anyway, are you sure that the GPS unit is faulty? Can you test it alone?
The unit is responsive on the serial port? Is the Z3801A sending commands?
Can you verify with a 'scope on the serial line if there is any signal?
On Sun, Sep 16, 2012 at 2:54 PM, Mike S mi...@flatsurface.com wrote:
On
I just bought a second-hand Z3801A, it also had a error message when self test
- GPS Rcv error, and I saw a red LED on main board on. I want test it alone but
I don't know GPS board's pin define, can someone tell me? Thanks.
Hui
At 2012-09-16 21:20:26,Azelio Boriani azelio.bori...@screen.it
Hi
It's probably easier to just make up an emulator for the UT rather than doing
it on a string by string basis. Only one of the strings needs to synch up with
the PPS. The rest can all be generated as needed. I'm not saying it would be
easy, only easier.
Maybe put something like an LEA-6T
HI
This is a pretty good start:
http://www.febo.com/pages/hardware/VPCommands.pdf
http://gpsd.berlios.de/vendor-docs/motorola/toc.pdf
There are lots of other references out there.
Bob
On Sep 16, 2012, at 9:38 AM, Hui Zhang ba...@163.com wrote:
I just bought a second-hand Z3801A, it also
In message ce93652a-1da6-48e3-9883-d7616ac24...@rtty.us, Bob Camp writes:
Bob,
There's one thing makes me scratch my head here: Why do you keep
arguing like the timeconstant cannot be changed dynamically ?
I use a very aggresive timeconstants initially, to quickly get the
phase offset under
I just acquired one of fluke.l's Samsung labeled z3805a units (the one
with double-oven 10811A, 2 10 MHz, 2 PPS, and 2 comm ports. Bob tells
me that the comm ports are configured for RS-232, but I haven't powered
the thing up yet (still working on power supply) so haven't inspected
what the
I've been unable to ship this summer but I am back now and have PC boards for
the PICTIC II and DMDT projects for 8 USD each plus shipping. If you are
interested please reply direct to me and not the list. If you have questions
please check links below. Will also help with parts that are not
In message 5C52FBDBA5084AD4A36300FBA73BEF5E@pc52, Tom Van Baak writes:
Yes, timing accuracy has been my main focus and in general I have been
using integration times on the low side of 1 seconds for that,
but it depends a lot on the OCXO/Rb and environment.
The PLL in NTPns is a (by now)
On Sat, Sep 15, 2012 at 7:04 PM, paul swed paulsw...@gmail.com wrote:
As Bob mentions there may be more to it then just nailing that particular
command.
But worth taking a look after I deal with the wwvb psk issue. As far as the
5 to 3 V I would just use a 3 term reg like the cherry semi chip.
On 09/16/2012 05:47 PM, Poul-Henning Kamp wrote:
In message5C52FBDBA5084AD4A36300FBA73BEF5E@pc52, Tom Van Baak writes:
Yes, timing accuracy has been my main focus and in general I have been
using integration times on the low side of 1 seconds for that,
but it depends a lot on the OCXO/Rb
Hi
The time constant can indeed be changed dynamically, that's what is often done.
The purpose of my examples was to keep things simple and look at the running
condition of the loop rather than it's performance while it settles down.
Bob
On Sep 16, 2012, at 9:49 AM, Poul-Henning Kamp
In message 50560a58.5010...@rubidium.dyndns.org, Magnus Danielson writes:
What I did instead was to (badly) reinvent Shewarts ideas for testing
if the phase residual is under statistical process control:
I increase the timeconstant if the phase residual has too frequent
zero-crossings and
Hi
By far the most common approach to optimizing these is the measure it and see
approach.
1) measure the noise out of the GPS ( must be done no matter what)
2) measurer the noise of the specific OCXO (again must be done)
3) *guess* at a cross over
4) try it and measure the result.
5) step and
In message acd158ca-d76c-4a8b-b77d-4fa691d0b...@rtty.us, Bob Camp writes:
The purpose of my examples was to keep things simple and look at
the running condition of the loop rather than it's performance
while it settles down.
But what is running condition ?
I see my PLL adjust to thermal
In message 3a001267-52de-4ee9-b6ee-6638fb270...@rtty.us, Bob Camp writes:
Hi
By far the most common approach to optimizing these is the measure
it and see approach.
1) measure the noise out of the GPS ( must be done no matter what)
2) measurer the noise of the specific OCXO (again must be done)
Great dialog, One thing I have seen is the Allan intercept almost always has a
knee. If you wanted the best possible GPS quartz reference developing a
variable Allan intercept would allow this knee to be moved and then
mathematically removed during a gated measurement.
Allowing to effectively
Am 20.07.2012 00:57, schrieb Richard (Rick) Karlquist:
A fast comparator seems like a good idea, and it
is simple, however it is actually the last thing
you want to use. High thermal sensitivity and high jitter.
Rick
On 7/19/2012 1:35 PM, Dan Kemppainen wrote:
Or use a fast comparator such
Hi
The basic assumption is that this is a lab gizmo and that there is indeed a
static adev (or very low frequency phase noise) plot for the OCXO (or Rb). The
other assumption is that this plot is quite good (say decreasing or flat to
10,000 seconds).
IF that's all true, then the running
Hi
The knee is a basic artifact of the cross over in the noise of one (say the
OCXO) to the noise of the other (say the GPS). It's one of those things you can
reduce, but never eliminate completely. The noise of the combined pair will
always be slightly worse than the best of the two when
In message bay162-w9fff4214c4de8fd1752f3df...@phx.gbl, Tom Knox writes:
Great dialog, One thing I have seen is the Allan intercept almost
always has a knee. If you wanted the best possible GPS quartz
reference developing a variable Allan intercept would allow this
knee to be moved and then
In message 2dea9396-95eb-4092-a443-a72350cc1...@rtty.us, Bob Camp writes:
The basic assumption is that this is a lab gizmo and that there
is indeed a static adev (or very low frequency phase noise) plot
for the OCXO (or Rb).
Bob,
I think this is where the premier-league differs from the
On 9/16/2012 12:03 PM, Gerhard Hoffmann wrote:
Am 20.07.2012 00:57, schrieb Richard (Rick) Karlquist:
A fast comparator seems like a good idea, and it
is simple, however it is actually the last thing
you want to use. High thermal sensitivity and high jitter.
Rick
On 7/19/2012 1:35 PM, Dan
Hi
…but endless testing for minimal return is what being a Time Nut is all about ….
Bob
On Sep 16, 2012, at 3:39 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote:
In message 2dea9396-95eb-4092-a443-a72350cc1...@rtty.us, Bob Camp writes:
The basic assumption is that this is a lab gizmo and
On 16 Sep, 2012, at 00:40 , Tom Van Baak wrote:
I worry in your example about the long cross-over time. This may be ideal for
frequency stability, but probably is not good for time accuracy. If one is
using the GPSDO as a timing reference, I would think a shorter time constant
will keep
On 9/16/12 10:20 AM, Magnus Danielson wrote:
On 09/16/2012 05:47 PM, Poul-Henning Kamp wrote:
Dave Mills coined the term allan intercept as the cross over of
the two sources allan variances and it's a good google search for
his relevant papers.
I'm not entirely sure his rule of thumb for
In message 34d5c3ce-6b3d-4944-996a-7637373b2...@gmail.com, Dennis Ferguson wr
ites:
I'm not sure there could be a difference between the goals of
frequency accuracy and time accuracy that would effect that time
constant.
It does.
A PLL more or less corresponds to an PI regulation, where a FLL
Some GPSDO have both a 1PPS and a PP2S (pulse per 2 second) output. I have two
questions for one of you telecom experts: 1) What is the history, and the
purpose of that PP2S signal? 2) What is the official spec for which second the
PP2S lands on? Is it odd seconds or even seconds? Is it GPS
On 09/16/2012 10:28 PM, Jim Lux wrote:
On 9/16/12 10:20 AM, Magnus Danielson wrote:
On 09/16/2012 05:47 PM, Poul-Henning Kamp wrote:
Dave Mills coined the term allan intercept as the cross over of
the two sources allan variances and it's a good google search for
his relevant papers.
I'm not
On 09/16/2012 10:30 PM, Poul-Henning Kamp wrote:
In message34d5c3ce-6b3d-4944-996a-7637373b2...@gmail.com, Dennis Ferguson wr
ites:
I'm not sure there could be a difference between the goals of
frequency accuracy and time accuracy that would effect that time
constant.
It does.
A PLL more or
On 16 Sep, 2012, at 17:11 , Tom Van Baak wrote:
Some GPSDO have both a 1PPS and a PP2S (pulse per 2 second) output. I have
two questions for one of you telecom experts: 1) What is the history, and the
purpose of that PP2S signal? 2) What is the official spec for which second
the PP2S lands
Per the 58503B brochure:
An even-second (1 PP2S) output is available as an option to the 58503B.
The even-second output option provides one pulse every other second,
synchronized to the even seconds in GPS time. This is the reference time
used in CDMA base stations.
Some GPSDO have both a 1PPS
In message 505642f5.1000...@rubidium.dyndns.org, Magnus Danielson writes:
On 09/16/2012 10:30 PM, Poul-Henning Kamp wrote:
A good PI-based PLL actually combines the FLL and PLL domains [...]
But it is the phase correction that doubles the (absolute) magnitude
of the frequency noise, by
On 16 Sep, 2012, at 16:30 , Poul-Henning Kamp wrote:
In message 34d5c3ce-6b3d-4944-996a-7637373b2...@gmail.com, Dennis Ferguson
wr
ites:
I'm not sure there could be a difference between the goals of
frequency accuracy and time accuracy that would effect that time
constant.
Note that
In message ad054298-f656-477f-9fb1-5d48c1b07...@gmail.com, Dennis Ferguson wr
ites:
If you
are using a PLL in both cases, however, then the problems are
essentially the same.
Well, not quite: Depending on the stiffness of your PLL, you can
minimize phase error at the cost of frequency error or
Sorry I should have said pulse per even second. I recall the pulses are
aligned with the UTC even second.
--- On Sun, 9/16/12, Mark Spencer mspencer12...@yahoo.ca wrote:
From: Mark Spencer mspencer12...@yahoo.ca
Subject: Re: Even pulse per second signals
To: time-nuts@febo.com
Received:
HI
In some cases, the difference can be your definition of time accuracy. If
short term GPS time is what you are worried about, then indeed that's a
different beast than a 30 day plot against your direct line to USNO.
Bob
On Sep 16, 2012, at 4:12 PM, Dennis Ferguson
On 09/16/2012 11:47 PM, Poul-Henning Kamp wrote:
In message505642f5.1000...@rubidium.dyndns.org, Magnus Danielson writes:
On 09/16/2012 10:30 PM, Poul-Henning Kamp wrote:
A good PI-based PLL actually combines the FLL and PLL domains [...]
But it is the phase correction that doubles the
On 09/16/2012 11:51 PM, Poul-Henning Kamp wrote:
In messagead054298-f656-477f-9fb1-5d48c1b07...@gmail.com, Dennis Ferguson wr
ites:
If you
are using a PLL in both cases, however, then the problems are
essentially the same.
Well, not quite: Depending on the stiffness of your PLL, you can
In this green era here in the USA there is a big push toward CFL lighting.
Problem is I can see my CFL lighting on my PN measurements and other equipment.
I am finding it is very noisy so I have started researching cost effective LED
lighting and was amazed at what is available. On eBay there
Hi
The thing that makes the CFL's nasty for lab use are the cheap little switchers
built into them. Conventional LED lights also have cheap little switchers in
them. Doing them with a 30% efficient linear regulator gets you back to halogen
type lumens per watt...
Bob
On Sep 16, 2012, at 8:09
Another good source of low-noise lighting is marine hardware stores.
I owned a sailboat for a while. Sailboats are floating radio
stations. I had Marine HF and VHF and Radar all running off banks of
lead acid batteries. You have the same noise issues on the water as
in ham radio stations.
I've seen lots of halogen power supplies which use cheap switchers too!
On 9/16/2012 8:55 PM, Bob Camp wrote:
Hi
The thing that makes the CFL's nasty for lab use are the cheap little switchers
built into them. Conventional LED lights also have cheap little switchers in
them. Doing them with
The Z3805A has two serial ports:
* An
I/O Port (Port 1) 25-pin female DB series connector which provides a serial
interface under RS-232 control.
* A
second Output Port (Port 2) which provides a continuous (broadcast) time and
date serial output once every two seconds (even
HI
Most of my little desktop cheap halogens got turned into LED's a while back.
Forgot about them….
Bob
On Sep 16, 2012, at 9:06 PM, Peter Gottlieb n...@verizon.net wrote:
I've seen lots of halogen power supplies which use cheap switchers too!
On 9/16/2012 8:55 PM, Bob Camp wrote:
Hi
On 9/16/2012 8:09 PM, Tom Knox wrote:
In this green era here in the USA there is a big push toward CFL
lighting. Problem is I can see my CFL lighting on my PN measurements
and other equipment. I am finding it is very noisy
Run 12 VDC lighting, or hydrocarbon (NG/propane/naptha, which is noisy
12 volt Halogen from a big transformer run from a Variac if you want dimming.
As long as the Variac brushes aren't arcing that setup will create zero noise.
On 9/16/2012 9:55 PM, Mike S wrote:
On 9/16/2012 8:09 PM, Tom Knox wrote:
In this green era here in the USA there is a big push
If you dim the halogens, you will be operating them outside of the
temperature required for the Halogen Cycle to operate.
http://en.wikipedia.org/wiki/Halogen_lamp
Shorter filament life and bulb darkening.
That being said, I have a couple of halogen lights on dimmers and love them
-- I like the
In message 9ae0e07a-568c-43d1-8cb6-0d0e21ee6...@rtty.us, Bob Camp writes:
The thing that makes the CFL's nasty for lab use are the cheap
little switchers built into them. Conventional LED lights also have
cheap little switchers in them. Doing them with a 30% efficient
linear regulator gets you
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