Tom Van Baak wrote:
> Hal writes:
>
>> It might be possible to avoid hanging bridges by dithering
>> the sawtooth. I'm thinking of something like a heater under
>> the xtal for the GPS unit that gets driven by a medium
>> frequency - slow relative to the normal sawtooth but fast
>> relative to t
In message <[EMAIL PROTECTED]>, "Tom Van Baak" writes:
>Warm-up time --
>Many Rb will lock in 5 minutes, typically. Some Qz
>take much longer to get on-frequency from cold start.
>This can simplify the initial loop locking algorithm.
Initial capture is best done with a looser timecons
In the matter of lifetime (outside of MTBF issues), is it correct that
Rb has a built-in life limiting mechanism (the lamp wears out), where Qz
does not? If so, Rb oscillators will eventually fail but one might hope
a Qz oscillator may not.
Didier
Tom Van Baak wrote:
>> Hello folks,
>>
>> i li
> Hello folks,
>
> i like to play the bad boy again: My claim is
>
> a) that for most of us a GPSD Rb is of little to no
> use compared to a good GPSD xtal oscillator
Ulrich,
That's a rather general statement, but I understand what
you mean. Consider, instead of a bold general assertion
which ca
Yes, agreed!
> -Ursprüngliche Nachricht-
> Von: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Im Auftrag von Poul-Henning Kamp
> Gesendet: Mittwoch, 20. Dezember 2006 16:43
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] LPRO-101 w
At 10:25 AM 12/20/2006, you wrote:
>Hello folks,
>
>The controller's task is to always pour just enough fluid from the
>second pot into the first pot to keep the fluid level constant despite
>the fluid lost through the small hole. One refinement of the model is
>that we also consider that the amoun
In message <[EMAIL PROTECTED]>, "Ulrich Bangert" writes:
>a) that for most of us a GPSD Rb is of little to no use compared to a
>good GPSD xtal oscillator
... if your hold-over requirement is trivial.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
[EMAIL PROTECTED] | TCP/IP sin
f say 50 s to improve the ADEV for small
observation times.
Regards
Ulrich Bangert, DF6JB
> -Ursprüngliche Nachricht-> Von: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Im Auftrag von Brooke Clarke
> Gesendet: Dienstag, 19. Dezember 2006 20:05
> An: time-nuts@febo.com
>
Hal writes:
> It might be possible to avoid hanging bridges by dithering
> the sawtooth. I'm thinking of something like a heater under
> the xtal for the GPS unit that gets driven by a medium
> frequency - slow relative to the normal sawtooth but fast
> relative to the PLL time constant. This some
Hal Murray wrote:
>> Noise like the oncore sawtooth isn't always a bad thing.
>>
>
> I was going to comment on that area... Thanks for the reminder.
>
> The problem is that the sawtooth isn't noise in the normal Gaussian sense.
> If you happen to hit a long/wide hanging bridge, the resultin
> Noise like the oncore sawtooth isn't always a bad thing.
I was going to comment on that area... Thanks for the reminder.
The problem is that the sawtooth isn't noise in the normal Gaussian sense.
If you happen to hit a long/wide hanging bridge, the resulting offset may get
past your PLL fil
From: "Poul-Henning Kamp" <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
Date: Tue, 19 Dec 2006 23:17:03 +
Message-ID: <[EMAIL PROTECTED]>
> In message <[EMAIL PROTECTED]>, Magnus Danielson wri
> tes:
In message <[EMAIL PROTECTED]>, Magnus Danielson wri
tes:
>It actually uses the CPU builtin counter, which
>will do for the purpose. They could have spent a little more and got better
>single shot resolution out of it, but I suspect they didn't see the need.
They are limited by digital noise insi
From: Dr Bruce Griffiths <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
Date: Wed, 20 Dec 2006 11:24:42 +1300
Message-ID: <[EMAIL PROTECTED]>
> Magnus Danielson wrote:
> > From: Brooke Clarke <[EMAIL PROTECTED]>
>
From: Magnus Danielson <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
Date: Tue, 19 Dec 2006 23:00:55 +0100 (CET)
Message-ID: <[EMAIL PROTECTED]>
> From: Brooke Clarke <[EMAIL PROTECTED]>
> Subject: Re: [time-nuts] LPR
Magnus Danielson wrote:
> From: Brooke Clarke <[EMAIL PROTECTED]>
> Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
> Date: Tue, 19 Dec 2006 13:42:28 -0800
> Message-ID: <[EMAIL PROTECTED]>
>
>
>> Hi Brendan:
>>
>>
From: Brooke Clarke <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
Date: Tue, 19 Dec 2006 13:42:28 -0800
Message-ID: <[EMAIL PROTECTED]>
> Hi Brendan:
>
> It's interesting that the PRS10 can time stamp the 1 PPS inpu
Hi Brendan:
It's interesting that the PRS10 can time stamp the 1 PPS input with a
resolution of 10 ns. I wonder how they do that.
http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf
When I picked up my PRS10 at the factory during the tour I learned that
the 10 MHz oscillator in the PRS10
On Tue, 2006-12-19 at 11:05 -0800, Brooke Clarke wrote:
> Hi Brendan:
>
> Keep in mind that this design does work and that the above items relate
> to optimization not bug fixes.
I currently have the Brooks Shera design disciplining my LPRO-101
without any mods and using the ADC connected direc
Hi Brendan:
It's my take that there are two aspects of the Brooks (no relation)
design that need to be addressed for optimum operation:
1. the filter time constants of the stock design are not correct for a
Rb oscillator, and that can be fixed by getting a custom PIC from Brooks.
2. the TIC alth
My original Question has sparked off quite an interesting discussion and
I learnt a lot
Since it seems that the Brooks Shera Project is not the optimum way of
GPS disciplining a Rubidium Oscillator can anyone here point me in the
direction of other DIY projects (or even ideas) that might yield a
[EMAIL PROTECTED] wrote:
Hi Bruce,
great ideas, thanks!
Said
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Said
Attached circuit illustrates how a PT100 may be interfaced to a single
ch
Hi Bruce,
great ideas, thanks!
Said
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[EMAIL PROTECTED] wrote:
> Hi Bruce,
>
> would you have pointers to good temperature sensing circuits with sub
> millidegree resolution?
>
> thanks,
> Said
> ___
> time-nuts mailing list
> time-nuts@febo.com
> https://www.febo.com/cgi-bin/mailman/li
[EMAIL PROTECTED] wrote:
> Hi Bruce,
>
> would you have pointers to good temperature sensing circuits with sub
> millidegree resolution?
>
> thanks,
> Said
> ___
> time-nuts mailing list
> time-nuts@febo.com
> https://www.febo.com/cgi-bin/mailman/li
Hi Bruce,
would you have pointers to good temperature sensing circuits with sub
millidegree resolution?
thanks,
Said
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[EMAIL PROTECTED] wrote:
>
>
> Hi Ulrich,
>
> good details on how to set the time constant for best GPSDO performance etc!
>
> Some issues you did not mention are but that are essential to get a good
> GPSDO are:
>
>* Aging compensation
>
>* Temperature compensation
>
>
Hi Ulrich,
good details on how to set the time constant for best GPSDO performance etc!
Some issues you did not mention are but that are essential to get a good
GPSDO are:
* Aging compensation
* Temperature compensation
* fault recovery, such as mechanical shock to crystal
In a message dated 12/16/2006 12:31:31 Pacific Standard Time,
[EMAIL PROTECTED] writes:
In message <[EMAIL PROTECTED]>, Hal
Murray writes:
>
>> You still want to produce some form of quality measure for the ADEV
>> shape in order to form some form of control loop.
>
>Suppose I build I goo
Hal Murray wrote:
>> You still want to produce some form of quality measure for the ADEV
>> shape in order to form some form of control loop.
>>
>
> Suppose I build I good GPSDO. How do I determine how good it is? (or even
> if it is any good)
>
> How much do I learn by just plotting the co
> Betreff: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS
> locking circuit
>
>
>
> > You still want to produce some form of quality measure for the ADEV
> > shape in order to form some form of control loop.
>
> Suppose I build I good GPSDO. How do I deter
In message <[EMAIL PROTECTED]>, Hal Murray writes:
>
>> You still want to produce some form of quality measure for the ADEV
>> shape in order to form some form of control loop.
>
>Suppose I build I good GPSDO. How do I determine how good it is? (or even
>if it is any good)
Since you pretty much
esendet: Samstag, 16. Dezember 2006 20:52
> An: Magnus Danielson
> Cc: time-nuts@febo.com
> Betreff: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS
> locking circuit
>
>
> In message <[EMAIL PROTECTED]>,
> Magnus Danielson writes:
>
> >You still wan
> You still want to produce some form of quality measure for the ADEV
> shape in order to form some form of control loop.
Suppose I build I good GPSDO. How do I determine how good it is? (or even
if it is any good)
How much do I learn by just plotting the control voltage?
How much do I learn
In message <[EMAIL PROTECTED]>, Magnus Danielson writes:
>You still want to produce some form of quality measure for the ADEV shape in
>order to form some form of control loop. It needs to be articulated.
Yes. I'll leave this as an exercise to the reader, only with the footnote
that what Dave Mi
From: "Poul-Henning Kamp" <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
Date: Sat, 16 Dec 2006 17:06:00 +
Message-ID: <[EMAIL PROTECTED]>
> In message <[EMAIL PROTECTED]>, Magnus Danielson writes:
>
>
In message <[EMAIL PROTECTED]>, Magnus Danielson writes:
>> The way you do this is by measuring the ADEV between your two sources
>> and how it changes with changes in your timeconstant.
>
>I.e. out of your TIC. The trouble is that you do not get one result but
>several. Either you just drive the
From: "Poul-Henning Kamp" <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
Date: Sat, 16 Dec 2006 15:56:32 +
Message-ID: <[EMAIL PROTECTED]>
> In message <[EMAIL PROTECTED]>, "Ulrich Bangert" writ
In message <[EMAIL PROTECTED]>, "Ulrich Bangert" writes:
>Poul,
>
>i appreciate your comments always a lot! But dynamical methods are
>especially usefull when the input parameters are subject of change,
>aren't they?
They are also very useful for amateur projects where the users do
not have the ne
PROTECTED]
> [mailto:[EMAIL PROTECTED] Im Auftrag von Poul-Henning Kamp
> Gesendet: Samstag, 16. Dezember 2006 15:32
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS
> locking circuit
>
>
>
In message <[EMAIL PROTECTED]>, "Ulrich Bangert" writes:
>ONE SIMPLE RULE applies to this question despite the fact that some math
>for drawing tau-sigma-diagrams is indispensable.
Ulrich,
The real challenge is to build an algorithm which finds this point dynamically.
--
Poul-Henning Kamp
tion required to avoid
> degrading the performance of an M12+ by using a clock
> frequency of 1GHz or more. Thus this method is probably too
> expensive and difficult to implement.
Bruce, the clue is NOT to go out for a high clock frequency. Instead
search for sub-clock interpolation
Brooks Shera wrote:
> - Original Message -
> From: "Ulrich Bangert" <[EMAIL PROTECTED]>
> To: "'Discussion of precise time and frequency measurement'"
>
> Sent: Friday, December 15, 2006 05:47
> Subject: Re: [time-
- Original Message -
From: "Ulrich Bangert" <[EMAIL PROTECTED]>
To: "'Discussion of precise time and frequency measurement'"
Sent: Friday, December 15, 2006 05:47
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
Brooke Clarke wrote:
> Hi Ulrich:
>
> I think the answer is what other low cost options are available? I
> would like to have a more modern TIC capability to add to the clock I'm
> working on. But although there's been a lot of discussion about
> different ways of making TIC measurements, it's
Hi Ulrich:
I think the answer is what other low cost options are available? I
would like to have a more modern TIC capability to add to the clock I'm
working on. But although there's been a lot of discussion about
different ways of making TIC measurements, it's not clear to me how to
do it o
-
> Von: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Im Auftrag von Tom Van Baak
> Gesendet: Freitag, 15. Dezember 2006 08:23
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS
> locking circuit
>
&
> Tom
>
> A TIC with 0.5ns jitter at 1 second isn't actually too much in the way
> of overkill when the PPS signal has 2ns of jitter.
Bruce,
Can you clarify about the jitter, though. The TIC jitter
that was quoted (500 ps) is the single-shot resolution
for the 53131A. The "2 ns" M12+ jitter is
On Fri, December 15, 2006 0:55, Dr Bruce Griffiths said:
>
> Björn
>
> You will need a dual frequency receiver to more accurately correct for the
> ionospheric delay.
Sure, that is an improvement. But how large is really the time rate of
change of the ionosphere? (Depends on the solar activity nat
From: [EMAIL PROTECTED]
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
Date: Fri, 15 Dec 2006 00:21:25 +0100 (CET)
Message-ID: <[EMAIL PROTECTED]>
> On Thu, December 14, 2006 23:07, Dr Bruce Griffiths said:
>
> > Thus devising inexpensive ph
From: Dr Bruce Griffiths <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
Date: Fri, 15 Dec 2006 12:55:19 +1300
Message-ID: <[EMAIL PROTECTED]>
> Björn
Bruce,
> You will need a dual frequency receiver to more accurately correct
[EMAIL PROTECTED] wrote:
> On Thu, December 14, 2006 23:07, Dr Bruce Griffiths said:
>
>
>> Thus devising inexpensive phase detectors/TICs with subnanosecond
>> performance allows one to take advantage of improvements in GPS timing
>> receiver performance when they occur.
>>
>> The possibility o
[EMAIL PROTECTED] wrote:
> On Thu, December 14, 2006 23:07, Dr Bruce Griffiths said:
>
>
>> Thus devising inexpensive phase detectors/TICs with subnanosecond
>> performance allows one to take advantage of improvements in GPS timing
>> receiver performance when they occur.
>>
>> The possibility o
On Thu, December 14, 2006 23:07, Dr Bruce Griffiths said:
> Thus devising inexpensive phase detectors/TICs with subnanosecond
> performance allows one to take advantage of improvements in GPS timing
> receiver performance when they occur.
>
> The possibility of utilising GPS carrier phase tracking
Tom Van Baak wrote:
>> But is it really an improvement that you get out of it? The answer is
>> NO! He, why not? The answer is: Because you have to PAY the increase in
>> precision with the increase in observation time. For every increase of
>> 10 in precision you need to increase the observation t
> But is it really an improvement that you get out of it? The answer is
> NO! He, why not? The answer is: Because you have to PAY the increase in
> precision with the increase in observation time. For every increase of
> 10 in precision you need to increase the observation time by 10!
Ulrich,
Th
limited changes in the LO frequency and it depends on the loop time
constant and some parameters more whether the so induced LO's frequency
changes stay within allowable bounds or not.
Best regards
Ulrich Bangert, DF6JB
> -Ursprüngliche Nachricht-
> Von: [EMAIL PROTECTED]
> [ma
Tom Van Baak wrote:
>> On the subject of Brooks Shera's design, the one thing that troubles me is
>>
> the
>
>> use of a 24 MHz oscillator to count the width of the 1PPS signal.
>> This yields a precision of 4.16e-8, but does it really?
>>
>
> No, with averaging it's much better than t
the problem of locking to the undesired harmonic.
>
> Jack
>
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
> Of Dr Bruce Griffiths
> Sent: Wednesday, December 13, 2006 7:52 PM
> To: Discussion of precise time and frequency measure
> On the subject of Brooks Shera's design, the one thing that troubles me is
the
> use of a 24 MHz oscillator to count the width of the 1PPS signal.
> This yields a precision of 4.16e-8, but does it really?
No, with averaging it's much better than that.
> This oscillator is uncontrolled and any d
I'm sure Brooks Shera can describe the nuances of his GPS locking circuit
far better than I can; but that said, the 24MHz oscillator is not used to
directly count the 1PPS signals. It is used over a 30 second measurement
interval, yielding a precision of about 1.4nS per count. Also the digital
-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
Of Dr Bruce Griffiths
Sent: Wednesday, December 13, 2006 7:52 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
The Brooks Shera circuit relies on
t; with an LPRO attached directly to the DAC.
> Enjoy!
> Richard
>
> - Original Message -
> From: "Brendan Minish" <[EMAIL PROTECTED]>
> To: "Discussion of precise time and frequency measurement"
>
> Sent: Wednesday, December 13, 2006 9:13 AM
> the one thing that troubles me is the use of a 24 MHz oscillator to
> count the width of the 1PPS signal. This yields a precision of
> 4.16e-8
> Question: Why not multiply the VCXO or OCXO output by 5 or 10 and run
> that into 24 or 32 bit counter? OR just sample the counter on every
> 10th PP
al Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
Of Richard H McCorkle
Sent: Wednesday, December 13, 2006 4:44 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
Hi Brendan,
I would
ROTECTED]>
To: "Discussion of precise time and frequency measurement"
Sent: Wednesday, December 13, 2006 9:13 AM
Subject: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit
> Hi I am looking for info on using the Brooks Shera GPS-VCXO Controller
> with an EFRATOM LPRO
Hi I am looking for info on using the Brooks Shera GPS-VCXO Controller
with an EFRATOM LPRO-101?
I currently have it locking an old and unknown single oven Xtal
oscillator this is working as well but I hope to replace this with the
LPRO-101
Has anyone any suggestions as to how best to choose the
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