Hi Bill,
should have added a disclaimer, I am involved with Jackson Labs Tech..
The Trimble part with oscillator looks interesting, probably an NCO not a
GPSDO I would think. They are as usually not putting any real data in their
specsheets.. The TCXO they are using will determine performa
Here is a typical high end OCXO. (It may blow your budget, but we can use it
as an example.)
http://www.mti-milliren.com/ocxo_270_ocxo.html
The typical 5 MHz aging performance is 5E-10
per day and 5E-08 per year.
That's not in the right ballpark.
Here's another way to look at it.
A typica
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On Feb 19, 2012, at 10:20 PM, Dennis Ferguson wrote:
> I think you may find that in many (most?) other
> countries the GSM BTS gear has no idea what time it is.
Pretty wide range there… I've certainly seen some pretty crazy time-and-dates
show up
On 19 Feb, 2012, at 21:08 , Bill Woodcock wrote:
> It's my assumption that some of them will be able to get enough GPS signal
> (or GPS via a GSM BTS, as we also have a Sierra Wireless GSM chipset onboard)
> and would thus be able to act as Stratum 1 servers for the others.
In the US I suspect
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On Feb 19, 2012, at 9:02 PM, saidj...@aol.com wrote:
> this is potentially possible with the small M9108
> or the Jackson Labs Technologies GPSTCXO.
Thanks for the pointer to both of them… It looks like Jackson Labs have
several interesting simil
Hi Bill,
the good news is that industrial units are becoming as inexpensive as hobby
type units..
bye,
Said
In a message dated 2/19/2012 21:48:36 Pacific Standard Time, wb6...@cox.net
writes:
Hi Said,
That may be, but I think he indicated he was using the common hobby type
units.
Hi Said,
That may be, but I think he indicated he was using the common hobby type units.
I
seriously don't think they measure up to your unit. I should have stated I was
speaking specifically about GPS by itself not using differential methods.
Your comments are noted, however. Thanks,
Bill..
In a message dated 2/19/2012 21:21:35 Pacific Standard Time, wb6...@cox.net
writes:
Doing a few fixes for 30 minutes will, under best conditions, get you
somewhere on a circumference around your location with a radius of 15 meters
(50 feet). For GPS to get a useful coordinate result with m
> From that point forward (and we hope the devices will have an operational
> life of at least ten years) they'll be dependent on their internal clock and
> NTP, but we really need them to stay synchronized to within 100
> microseconds. 10 microseconds would be ideal, but 100 would be acceptable.
Hello Bill Woodcock,
Many, many questions come to mind. Is this a fixed network that never changes
its character ? Or by network do you mean via the internet where you have no
control over path variations ? I guess the latter based upon your comments
thus far.
What is driving the requiremen
> ... but then they get taken indoors and plugged into the network, and
> probably never get a clear view of a GPS or GLONASS satellite again.
A high-sensitivity GPS receiver might still give useful results here,
especially if it has a high-quality reference oscillator like an OCXO.
Even 20 or 3
On Sun, Feb 19, 2012 at 5:48 PM, Bill Woodcock wrote:
..
> So that's something I've been having a hard time understanding… If that's
> the amount of inaccuracy _per oscillation_, then at the time-scales I'm
> dealing with, it would quickly accumulate and become unuseful…
I think you have it ri
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On Feb 19, 2012, at 7:28 PM, Dennis Ferguson wrote:
> 10, or even 100, microseconds is tough with NTP. I don't think it is
> impossible, but it
> requires a good, reliable network connection…
We will have a very large mesh of devices, but the con
Hello Bill,
this is potentially possible with the small M9108 or the Jackson Labs
Technologies GPSTCXO.
Some caveats:
1) The Trimble Resolution-T May work, but the above stated units have a 50
channel WAAS/EGNOS/MSAS GPS receiver and are also GPS Disciplined
Oscillators not just timing
On Sun, Feb 19, 2012 at 3:56 PM, Bill Woodcock wrote:
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>
> Hi. This is my first posting to this list, and I'm not a timekeeping
> engineer, so my apologies in advance for my ignorance in this area.
>
> I'm building a small device to do one-way de
On 19 Feb, 2012, at 15:56 , Bill Woodcock wrote:
> Hi. This is my first posting to this list, and I'm not a timekeeping
> engineer, so my apologies in advance for my ignorance in this area.
>
> I'm building a small device to do one-way delay measurements through network.
> Once I'm done with
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On Feb 19, 2012, at 5:07 PM, Bill Hawkins wrote:
> If you are going to correct it with NTP, a simple crystal
> oscillator will do.
Yeah, my assumption was that something like a DOCXO or a VCTCXO would be about
the best I'd get within budget. But
What you are looking for is the Caesium standard on a chip that
is presently only available for mostly military projects. This
will become available as war surplus after WW III.
But if you are going to correct it with NTP, a simple crystal
oscillator will do. If you're using NTP, why do you need t
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Hi. This is my first posting to this list, and I'm not a timekeeping engineer,
so my apologies in advance for my ignorance in this area.
I'm building a small device to do one-way delay measurements through network.
Once I'm done with prototyping
Thank you, Tom.
I REALLY look forward to your tutorials. How interesting and thought
provoking for you to take your time(sic) for such.
Thanks a million.
-Don
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From: time-nuts-boun...@febo.com [mailto
On 2/19/12 2:47 PM, Tom Van Baak wrote:
There seems to be some confusion about stability and drift; about
ADEV and other tools. The tone of this thread is not heading in a
positive direction.
So instead I will offer to put together a short tutorial or series of
tutorials that focus on factual ed
There seems to be some confusion about stability and drift; about
ADEV and other tools. The tone of this thread is not heading in a
positive direction.
So instead I will offer to put together a short tutorial or series of
tutorials that focus on factual education and gracious explanation.
Give m
John said in part;
ignore the last two (ADEV) plot points as there isn't enough data for
them to be very meaningful.
you need a lot more than 10 days data to draw any real conclusions;
IMHO, ADEV is not the right tool or even a very useful tool for evaluation
the long term performance of the
"Do you believe there may be a problem for those who are
reverse-engineering, and posting on the open net, items which may be
covered under these regulations?
If you do, you may want to consider contacting them off-list and letting
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Man, export controls are
Hi Warren -- for these tests, I wasn't capturing raw data, jut using the tables
and graphs that come out of the TSC box.
John
On Feb 18, 2012, at 11:57 PM, "ws at Yahoo" wrote:
> John
>
> If you have the raw phase data, can you post a plot of what the well filtered
> freq offset looks like o
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