satellite you would track at which time. The BIPM used to generate and
years ago - I think this is what you mean by "ephemerides".
noise by sqrt(N) roughly speaking. You can either do common view, where you
visible at each location, and then difference. Common view gives you less
on short baselines. However as the baseline increases in length, the number
of satellites in common view decreases and the statistical noise increases.
satellites are used. You can improve the processing by doing things like
weighting the satellites according to their elevation.
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.
Post by JF PICARD via time-nutsHello,
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-nutsHello,
I am looking for a time transfer
system Ashtech Z12T or equivalent. Thank you.
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