Date: Thu, 18 Dec 2003 11:34:57 -0800
From: Pascal Willis <Pascal.R.Willis@jpl.nasa.gov>
To: Martine Feissel <feissel@ensg.ign.fr>
Subject: Fwd: Choice of satellite codes for CGGTTS standard format

>Date: Thu, 18 Dec 2003 19:27:10 +0100
>From: "W. Lewandowski" <wlewandowski@bipm.org>
>Subject: Choice of satellite codes for CGGTTS standard format
>To: wlewandowski@bipm.org
>
>To the CGGTTS distribution list:
>
>Dear Colleagues,
>
>At the request of Judah Levine, the chairman of the CCTF Group on GNSS
>Time Transfer Standards (CGGTTS), I am forwarding you his comments and
>questions about the choice of satellite codes for CGGTTS standard
>format.
>
>
>With best wishes for upcoming holiday season and the new year,
>Wlodek Lewandowski
>Secretary of the CGGTTS
>
>-----------------------------------------------------------------------
>Dear Colleagues,
>    At the recent meeting of the BIPM committee on time transfer
>standards, which was held in San Diego the evening before the
>PTTI meeting, we discussed the problem of combining the data from
>different satellite systems. As you may recall, we suggested using the
>100s digit of the SV/PRN number to indicate the source of the data.
>However, there are a number of different satellite systems that are now
>operational or are proposed, and it would be best to adopt a system that
>was compatible with as many of them as possible.
>    The SV number is treated as a numerical value by many of the existing
>programs, and it would be best to preserve this design. Therefore, using
>a prefix letter to identify the source of the data is not desirable,
>since it would cause problems with many existing programs, which expect
>only a numerical value in this field. (However, this would be possible
>in principle if no other solution can be found.)
>    I am writing to ask for your assistance and advice in this matter.
>Please help me by answering the following questions:
>
>    1. Do you currently use data from systems other than GPS or do you
>plan to do so in the near future? Other systems include GLONASS, or any
>augmentation system.
>    2. If the answer to question 1 is yes, how do you identify the
>source of the data? Do you use the SV/PRN number or some other method?
>    3. Do you have any suggestions about how the data from the
>different satellite systems should be identified? If we were to
>decide to use the 100s digit of the SV/PRN number for this purpose, do
>you have any specific suggestions about which values to use?
>
>Please reply to me or to Wlodek at the BIPM. It would be most helpful if
>you could reply by the end of January.
>
>Please forward this letter to any colleague who might be interested in
>this matter.
>
>Thank you for your assistance and advice.
>
>With best wishes for the new year,
>
>Judah Levine
>Chair of the CGGTTS
>Time and Frequency Division
>NIST Boulder
>[jlevine@india.colorado.edu]
>________________________________________________________________________
>_
>
>  Wlodzimierz Lewandowski                     E-mail:
>wlewandowski@bipm.org
>  Bureau International des Poids et Mesures   Phone:  +33-1-45-07-70-63
>  92312 Sevres Cedex, France                  Fax:    +33-1-45-07-70-59
>                                              Web site: www.bipm.org
>________________________________________________________________________