Re: [time-nuts] Ashtech Z12T

[Magnus Danielson]

Hi Bob,

On 12/3/18 2:42 PM, Bob kb8tq wrote:
> 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
>  
> 
> 
> 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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Re: [time-nuts] Ashtech Z12T

[Michael Wouters]

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


On Tue, 4 Dec 2018 at 9:19 pm, JF PICARD  wrote:

> 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
> 
> On Mon, 12/3/18, Michael Wouters  wrote:
>
>  Subject: Re: [time-nuts] Ashtech Z12T
>  To: "Discussion of precise time and frequency measurement" <
> time-nuts@lists.febo.com>, "JF PICARD" 
>  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
>  Dec 2018 at 10:21 pm, JF PICARD via time-nuts 
>  wrote:
>  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 

Re: [time-nuts] Ashtech Z12T

[Michael Wouters]

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 <
time-nuts@lists.febo.com> wrote:

> 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  wrote:
>
>  Subject: Re: [time-nuts] Ashtech Z12T
>  To: "Discussion of precise time and frequency measurement" <
> time-nuts@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" 
>  To: 
>  Cc: "JF PICARD" 
>  Sent: Wednesday, November 28, 2018 9:33
>  AM
>  Subject: [time-nuts] Ashtech Z12T
>
>
>  > Hello,
>  > I am looking for a time transfer
>  system Ashtech Z12T or equivalent. Thank you.
>  >
>  >
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>
>
>
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Re: [time-nuts] Ashtech Z12T

[Don]

On Mon, 2018-12-03 at 08:42 -0500, Bob kb8tq wrote:
> https://www.thinksrs.com/downloads/pdfs/manuals/FS740m.pdfAnother 
https://www.thinksrs.com/downloads/pdfs/manuals/FS740m.pdf
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Re: [time-nuts] Ashtech Z12T

[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. 

Bob


> On Dec 3, 2018, at 6:19 AM, JF PICARD via time-nuts 
>  wrote:
> 
> 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  wrote:
> 
> Subject: Re: [time-nuts] Ashtech Z12T
> To: "Discussion of precise time and frequency measurement" 
> 
> 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
> 
>> On
> Nov 28, 2018, at 4:12 PM, Tom Van Baak 
> wrote:
>> 
>> 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" 
>> To: 
>> Cc: "JF PICARD" 
>> Sent: Wednesday, November 28, 2018 9:33
> AM
>> Subject: [time-nuts] Ashtech Z12T
>> 
>> 
>>> Hello,
>>> I am
> looking for a time transfer system Ashtech Z12T or
> equivalent. Thank you.
>>> 
>>> 
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>>> time-nuts mailing list -- time-nuts@lists.febo.com
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>>> and follow the instructions there.
>> 
> 
>> 
>> 
>> 
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> 
> 
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Re: [time-nuts] Ashtech Z12T

[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..

On Wed, 11/28/18, Tom Van Baak  wrote:

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

[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 - 
From: "JF PICARD via time-nuts" 
To: 
Cc: "JF PICARD" 
Sent: Wednesday, November 28, 2018 9:33 AM
Subject: [time-nuts] Ashtech Z12T


> Hello,
> I am looking for a time transfer system Ashtech Z12T or equivalent. Thank you.
> 
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[time-nuts] Ashtech Z12T

[JF PICARD via time-nuts]

Hello,
I am looking for a time transfer system Ashtech Z12T or equivalent. Thank you.

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