Discussion:
Ashtech Z12T
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JF PICARD via time-nuts
2018-11-28 17:33:38 UTC
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Hello,
I am looking for a time transfer system Ashtech Z12T or equivalent. Thank you.

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Tom Van Baak
2018-11-28 21:12:22 UTC
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The Z12T is a bit old by now, although some of us own or have used them. Z12 documentation is available on multiple archived Ashtech web sites. Lots of conference / technical papers describing time transfer with Z12T receivers exist. AFAIK a number of national timing labs still use them.

What is it you're trying to do? Do you own a Z12T and are just looking for spare parts? Or are you looking for modern time transfer via GPS / GNSS? If so, what level of timing accuracy are you looking for? Perhaps you could explain a bit more what your actual request is, or what timing infrastructure you already have running.

/tvb

----- Original Message -----
From: "JF PICARD via time-nuts" <time-***@lists.febo.com>
To: <time-***@lists.febo.com>
Cc: "JF PICARD" <***@yahoo.com>
Sent: Wednesday, November 28, 2018 9:33 AM
Subject: [time-nuts] Ashtech Z12T
Post by JF PICARD via time-nuts
Hello,
I am looking for a time transfer system Ashtech Z12T or equivalent. Thank you.
_______________________________________________
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and follow the instructions there.
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Bob kb8tq
2018-11-28 22:17:35 UTC
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Hi

Only as an example:

One key “feature” of the Z12T is the ability to come up with an absolute offset between a local
reference and GPS time. To some degree, that is as much a function of the Z12T being in some
sort of “round robin” comparison system as anything else. If that full offset information is part
of what you need, that adds even more complexity to the request.

A somewhat more modern approach than the Z12T would be one of the new(er) Novatel boards
and a bit of custom code running on it. Even there the same problem(s) with calibrating an
offset come up.

Note that indeed you *can* get a time offset number from a simulator feeding the device. How
good that number is (and how much you trust it) is very much a “that depends” sort of thing.
Again - right back to the “what are you trying to do?” question.

Bob
Post by Tom Van Baak
The Z12T is a bit old by now, although some of us own or have used them. Z12 documentation is available on multiple archived Ashtech web sites. Lots of conference / technical papers describing time transfer with Z12T receivers exist. AFAIK a number of national timing labs still use them.
What is it you're trying to do? Do you own a Z12T and are just looking for spare parts? Or are you looking for modern time transfer via GPS / GNSS? If so, what level of timing accuracy are you looking for? Perhaps you could explain a bit more what your actual request is, or what timing infrastructure you already have running.
/tvb
----- Original Message -----
Sent: Wednesday, November 28, 2018 9:33 AM
Subject: [time-nuts] Ashtech Z12T
Post by JF PICARD via time-nuts
Hello,
I am looking for a time transfer system Ashtech Z12T or equivalent. Thank you.
_______________________________________________
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
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JF PICARD via time-nuts
2018-12-03 11:14:44 UTC
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Permalink
Thank you for answer and sorry for delay. Purpose is simultaneous view of GPS satellites with the french official time laboratory LNE SYRTE . The corrections factors from the laboratory will enable to get with our high performance cesium about 5. 10-13 . Today the cesium is running alone. Discussion with some people involved in this worlwide common practice spoke about the Z12T but if there is anything more modern..
--------------------------------------------
On Wed, 11/28/18, Tom Van Baak <***@LeapSecond.com> wrote:

Subject: Re: [time-nuts] Ashtech Z12T
To: "Discussion of precise time and frequency measurement" <time-***@lists.febo.com>
Date: Wednesday, November 28, 2018, 10:12 PM

The Z12T is a bit old by now, although some
of us own or have used them. Z12 documentation is available
on multiple archived Ashtech web sites. Lots of conference /
technical papers describing time transfer with Z12T
receivers exist. AFAIK a number of national timing labs
still use them.

What is it you're trying to do? Do you
own a Z12T and are just looking for spare parts? Or are you
looking for modern time transfer via GPS / GNSS? If so, what
level of timing accuracy are you looking for? Perhaps you
could explain a bit more what your actual request is, or
what timing infrastructure you already have running.

/tvb

----- Original Message -----
From: "JF PICARD via time-nuts" <time-***@lists.febo.com>
To: <time-***@lists.febo.com>
Cc: "JF PICARD" <***@yahoo.com>
Sent: Wednesday, November 28, 2018 9:33
AM
Subject: [time-nuts] Ashtech Z12T
Post by JF PICARD via time-nuts
Hello,
I am looking for a time transfer
system Ashtech Z12T or equivalent. Thank you.
_______________________________________________
Post by JF PICARD via time-nuts
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions
there.



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Michael Wouters
2018-12-03 19:42:02 UTC
Reply
Permalink
Hello

There are many alternatives to the Z12T. It all depends on your budget. I
am guessing that you want to establish legal traceability to your local
UTC, is that right?

Starting at the top end, you can buy complete systems from Dicom and
Piktime. These cost about $25K and $40K respectively. These are
multi-frequency, multi-GNSS systems.

There are also some cheaper, single frequency systems (GPS only) available
too, from a company in Japan and one in the U.K. Just search for "time
transfer system".

Some NMIs in countries like Canada, Australia, Japan, ... offer remote
calibration services of the kind you want to set up. These are too far
away for common view but I suppose all in view would be the method in this
case ( you would still have traceability to your UTC via the CIPM Mutual
Recognition Agreement). Costs are something like $5K per year, in addition
to the hardware.

You can just buy a shiny new time-transfer receiver like the Septentrio
PolaRx5TRPRO with a geodetic antenna for about $20K. These are the most
popular in the timing community at the moment. But other receivers like
Javad and Trimble are good too.

If single frequency performance is good enough, and you're willing to do a
bit of work setting up software, then the really low cost solution is
something like the software from www.openttp.org
The main receiver supported, the NVS NV08C is less than $100. You can get
accurate antenna positions from this receiver in a base rover
configuration. All the rest is post processing and there are various
options here. You will also need a counter/timer and the low cost solution
here is the TAPR TICC, which is also supported by OpenTTP.

Cheers
Michael


On Mon, 3 Dec 2018 at 10:21 pm, JF PICARD via time-nuts <
Post by JF PICARD via time-nuts
Thank you for answer and sorry for delay. Purpose is simultaneous view of
GPS satellites with the french official time laboratory LNE SYRTE . The
corrections factors from the laboratory will enable to get with our high
performance cesium about 5. 10-13 . Today the cesium is running alone.
Discussion with some people involved in this worlwide common practice spoke
about the Z12T but if there is anything more modern..
--------------------------------------------
Subject: Re: [time-nuts] Ashtech Z12T
To: "Discussion of precise time and frequency measurement" <
Date: Wednesday, November 28, 2018, 10:12 PM
The Z12T is a bit old by now, although some
of us own or have used them. Z12 documentation is available
on multiple archived Ashtech web sites. Lots of conference /
technical papers describing time transfer with Z12T
receivers exist. AFAIK a number of national timing labs
still use them.
What is it you're trying to do? Do you
own a Z12T and are just looking for spare parts? Or are you
looking for modern time transfer via GPS / GNSS? If so, what
level of timing accuracy are you looking for? Perhaps you
could explain a bit more what your actual request is, or
what timing infrastructure you already have running.
/tvb
----- Original Message -----
Sent: Wednesday, November 28, 2018 9:33
AM
Subject: [time-nuts] Ashtech Z12T
Post by JF PICARD via time-nuts
Hello,
I am looking for a time transfer
system Ashtech Z12T or equivalent. Thank you.
_______________________________________________
Post by JF PICARD via time-nuts
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
Post by JF PICARD via time-nuts
and follow the instructions
there.
_______________________________________________
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and follow the instructions there.
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JF PICARD via time-nuts
2018-12-03 11:19:11 UTC
Reply
Permalink
Hello,

Thank you for answer and sorry for delay. As I explained to another answer, purpose is simultaneous view of GPS satellites with the french official time laboratory LNE SYRTE . The corrections factors from the laboratory will enable to get with our high performance cesium about 5. 10-13 . Offset is for us without any utility.
You spoke about Novatel boards ; can you please explain more.

JFP




--------------------------------------------
On Wed, 11/28/18, Bob kb8tq <***@n1k.org> wrote:

Subject: Re: [time-nuts] Ashtech Z12T
To: "Discussion of precise time and frequency measurement" <time-***@lists.febo.com>
Date: Wednesday, November 28, 2018, 11:17 PM

Hi

Only as an example:

One key “feature” of the Z12T is the
ability to come up with an absolute offset between a local

reference and GPS time. To some degree,
that is as much a function of the Z12T being in some
sort of “round robin” comparison system as
anything else. If that full offset information is part
of what you need, that adds even more
complexity to the request.

A somewhat more modern approach than the Z12T
would be one of the new(er) Novatel boards
and a bit of custom code running on it. Even
there the same problem(s) with calibrating an
offset come up.

Note that indeed you *can* get a time offset
number from a simulator feeding the device. How
good that number is (and how much you trust it)
is very much a “that depends” sort of thing.
Again - right back to the “what are you
trying to do?” question.

Bob
Post by Tom Van Baak
On
The Z12T
is a bit old by now, although some of us own or have used
them. Z12 documentation is available on multiple archived
Ashtech web sites. Lots of conference / technical papers
describing time transfer with Z12T receivers exist. AFAIK a
number of national timing labs still use them.
Post by Tom Van Baak
What is it
you're trying to do? Do you own a Z12T and are just
looking for spare parts? Or are you looking for modern time
transfer via GPS / GNSS? If so, what level of timing
accuracy are you looking for? Perhaps you could explain a
bit more what your actual request is, or what timing
infrastructure you already have running.
Post by Tom Van Baak
/tvb
----- Original
Message -----
Post by Tom Van Baak
From: "JF PICARD
Sent: Wednesday, November 28, 2018 9:33
AM
Post by Tom Van Baak
Subject: [time-nuts] Ashtech Z12T
Post by JF PICARD via time-nuts
Hello,
I am
looking for a time transfer system Ashtech Z12T or
equivalent. Thank you.
_______________________________________________
Post by Tom Van Baak
Post by JF PICARD via time-nuts
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
Post by Tom Van Baak
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
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Bob kb8tq
2018-12-03 13:42:57 UTC
Reply
Permalink
Hi

Ok, if frequency is the only concern, then a fairly conventional GPSDO would do the job.
One of many out there is the FS 740.

https://www.thinksrs.com/downloads/pdfs/manuals/FS740m.pdfAnother

There are a lot of others. The approach used is normally a very long comparison ( as in
weeks). The advantage is that they are pretty much “plug and play” with little intervention
required from the user.

The Novatel boards

https://www.novatel.com/assets/Documents/Papers/OEM7-Receivers-BR-D21517-v1.pdf <https://www.novatel.com/assets/Documents/Papers/OEM7-Receivers-BR-D21517-v1.pdf>

are a more “hands on” way to do the task. There would be some software development
required on your part to get them going. They would allow more careful control over the
exact nature of the comparison.

Indeed there are a number of similar devices on the surplus market. The two items above
are only a random selection of what’s out there.

In the US, NIST used to supply a service (for a charge of course) that set up a comparison
system at your location. I do not know if there are similar services available outside the US.

Bob
Post by JF PICARD via time-nuts
Hello,
Thank you for answer and sorry for delay. As I explained to another answer, purpose is simultaneous view of GPS satellites with the french official time laboratory LNE SYRTE . The corrections factors from the laboratory will enable to get with our high performance cesium about 5. 10-13 . Offset is for us without any utility.
You spoke about Novatel boards ; can you please explain more.
JFP
--------------------------------------------
Subject: Re: [time-nuts] Ashtech Z12T
Date: Wednesday, November 28, 2018, 11:17 PM
Hi
One key “feature” of the Z12T is the
ability to come up with an absolute offset between a local
reference and GPS time. To some degree,
that is as much a function of the Z12T being in some
sort of “round robin” comparison system as
anything else. If that full offset information is part
of what you need, that adds even more
complexity to the request.
A somewhat more modern approach than the Z12T
would be one of the new(er) Novatel boards
and a bit of custom code running on it. Even
there the same problem(s) with calibrating an
offset come up.
Note that indeed you *can* get a time offset
number from a simulator feeding the device. How
good that number is (and how much you trust it)
is very much a “that depends” sort of thing.
Again - right back to the “what are you
trying to do?” question.
Bob
Post by Tom Van Baak
On
The Z12T
is a bit old by now, although some of us own or have used
them. Z12 documentation is available on multiple archived
Ashtech web sites. Lots of conference / technical papers
describing time transfer with Z12T receivers exist. AFAIK a
number of national timing labs still use them.
Post by Tom Van Baak
What is it
you're trying to do? Do you own a Z12T and are just
looking for spare parts? Or are you looking for modern time
transfer via GPS / GNSS? If so, what level of timing
accuracy are you looking for? Perhaps you could explain a
bit more what your actual request is, or what timing
infrastructure you already have running.
Post by Tom Van Baak
/tvb
----- Original
Message -----
Post by Tom Van Baak
From: "JF PICARD
Sent: Wednesday, November 28, 2018 9:33
AM
Post by Tom Van Baak
Subject: [time-nuts] Ashtech Z12T
Post by JF PICARD via time-nuts
Hello,
I am
looking for a time transfer system Ashtech Z12T or
equivalent. Thank you.
_______________________________________________
Post by Tom Van Baak
Post by JF PICARD via time-nuts
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
Post by Tom Van Baak
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
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and follow the instructions there.
_______________________________________________
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Don
2018-12-03 14:49:25 UTC
Reply
Permalink
https://www.thinksrs.com/downloads/pdfs/manuals/FS740m.pdfAnother 
https://www.thinksrs.com/downloads/pdfs/manuals/FS740m.pdf
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Magnus Danielson
2018-12-04 21:50:24 UTC
Reply
Permalink
Hi Bob,
Post by Bob kb8tq
Hi
Ok, if frequency is the only concern, then a fairly conventional GPSDO would do the job.
One of many out there is the FS 740.
https://www.thinksrs.com/downloads/pdfs/manuals/FS740m.pdfAnother
There are a lot of others. The approach used is normally a very long comparison ( as in
weeks). The advantage is that they are pretty much “plug and play” with little intervention
required from the user.
The Novatel boards
https://www.novatel.com/assets/Documents/Papers/OEM7-Receivers-BR-D21517-v1.pdf <https://www.novatel.com/assets/Documents/Papers/OEM7-Receivers-BR-D21517-v1.pdf>
are a more “hands on” way to do the task. There would be some software development
required on your part to get them going. They would allow more careful control over the
exact nature of the comparison.
Indeed there are a number of similar devices on the surplus market. The two items above
are only a random selection of what’s out there.
In the US, NIST used to supply a service (for a charge of course) that set up a comparison
system at your location. I do not know if there are similar services available outside the US.
I've been shown one in a certain German vendors location as they just
recently got it. They where proud and happy. I really enjoyed seeing it
there, that they took the step.

Cheers,
Magnus

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Michael Wouters
2018-12-04 11:30:56 UTC
Reply
Permalink
Hello JF

(Ccing to time nuts because probably still of interest)
The TTR6 is a single channel receiver so you had to install an observing
schedule appropriate to your geographical region, which specified which
satellite you would track at which time. The BIPM used to generate and
distribute these schedules every 6 months or so but stopped doing this 7?
years ago - I think this is what you mean by "ephemerides".

If you have N satellites tracked then you can reduce the time transfer
noise by sqrt(N) roughly speaking. You can either do common view, where you
match satellites at each location and time, and then take an average of the
differences, or all in view, where you average all of the satellites
visible at each location, and then difference. Common view gives you less
noise (because of better cancellation of eg the effects of the ionosphere)
on short baselines. However as the baseline increases in length, the number
of satellites in common view decreases and the statistical noise increases.
At distances of a few thousand km, all in view starts to win because more
satellites are used. You can improve the processing by doing things like
weighting the satellites according to their elevation.

The current best method of doing GNSS time-transfer is PPP or precise point
positioning, and is a form of all in view, with much better post-processing
that uses both code and phase observatIons. You can do this with the
Septentrio receivers. But CGGTTS-based time transfer is still used in the
timing community.

Cheers
Michael
Post by JF PICARD via time-nuts
Hello,
Thank you very much for your explanations but, as a newbie in this immense
domain, I have got some questions. With the Allen Osborne TTR-6 we received
from the LNE SYRTE (french observatory) and loaded the ephemiredes (data
about the GPS satellites passing above us the next week or month) and we
will follow satellite X, the Y... , we sent our received data and we got
the data from LNE for the same satellite...
How does the actual system operate with several satellites ? I haven't
seen any mention (quick overlook in the data sheet) neither in the
Septentrio nor in the NVS...
Cheers.
JF
--------------------------------------------
Subject: Re: [time-nuts] Ashtech Z12T
To: "Discussion of precise time and frequency measurement" <
Date: Monday, December 3, 2018, 8:42 PM
Hello
There are many alternatives to the
Z12T. It all depends on your budget. I am guessing that you
want to establish legal traceability to your local UTC, is
that right?
Starting
at the top end, you can buy complete systems from Dicom and
Piktime. These cost about $25K and $40K respectively. These
are multi-frequency, multi-GNSS systems.
There are also some cheaper, single
frequency systems (GPS only) available too, from a company
in Japan and one in the U.K. Just search for "time
transfer system".
Some NMIs in countries like Canada,
Australia, Japan, ... offer remote calibration services of
the kind you want to set up. These are too far away for
common view but I suppose all in view would be the method in
this case ( you would still have traceability to your UTC
via the CIPM Mutual Recognition Agreement). Costs are
something like $5K per year, in addition to the
hardware.
You can just
buy a shiny new time-transfer receiver like the Septentrio
PolaRx5TRPRO with a geodetic antenna for about $20K. These
are the most popular in the timing community at the moment.
But other receivers like Javad and Trimble are good
too.
If single
frequency performance is good enough, and you're willing
to do a bit of work setting up software, then the really low
cost solution is something like the software from www.openttp.orgThe
main receiver supported, the NVS NV08C is less than $100.
You can get accurate antenna positions from this receiver in
a base rover configuration. All the rest is post processing
and there are various options here. You will also need a
counter/timer and the low cost solution here is the TAPR
TICC, which is also supported by OpenTTP.
CheersMichael
On Mon, 3
Thank you
for answer and sorry for delay. Purpose is simultaneous view
of GPS satellites with the french official time laboratory
LNE SYRTE . The corrections factors from the laboratory will
enable to get with our high performance cesium about 5.
10-13 . Today the cesium is running alone. Discussion with
some people involved in this worlwide common practice spoke
about the Z12T but if there is anything more modern..
--------------------------------------------
Subject: Re: [time-nuts] Ashtech Z12T
To: "Discussion of precise time and frequency
Date: Wednesday, November 28, 2018, 10:12 PM
The Z12T is a bit old by now, although some
of us own or have used them. Z12 documentation is
available
on multiple archived Ashtech web sites. Lots of conference
/
technical papers describing time transfer with Z12T
receivers exist. AFAIK a number of national timing labs
still use them.
What is it you're trying to do? Do you
own a Z12T and are just looking for spare parts? Or are
you
looking for modern time transfer via GPS / GNSS? If so,
what
level of timing accuracy are you looking for? Perhaps
you
could explain a bit more what your actual request is,
or
what timing infrastructure you already have running.
/tvb
----- Original Message -----
Sent: Wednesday, November 28, 2018 9:33
AM
Subject: [time-nuts] Ashtech Z12T
Post by JF PICARD via time-nuts
Hello,
I am looking for a time transfer
system Ashtech Z12T or equivalent. Thank you.
_______________________________________________
Post by JF PICARD via time-nuts
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
Post by JF PICARD via time-nuts
and follow the instructions
there.
_______________________________________________
To unsubscribe, go to
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and follow the instructions there.
_______________________________________________
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and follow the instructions there.
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