Subject: [SCIGN-0591] SCIGN Site Logs, ref Msg. # 590
From: Ruth Neilan
Date: 30 Jun 1999 17:38:42

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SCIGN Electronic Mail    Wed Jun 30 17:38:42 PDT 1999      Message Number 0591
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Author: Ruth Neilan
Subject: SCIGN Site Logs, ref Msg. # 590

Dear colleagues,

This message is in response to SCIGN mail message # 590 message concerning
SCIGN site log format changes. It is important to note that variations in
the fundamental format of the site logs can have an impact on other
processes   accessing the GPS data and ancillary information such as the
site log.

The SCIGN regional array has adopted a log format that differs from the
accepted log format used globally by all agencies associated with the IGS.
For analysts who use only data and information from SCIGN, this may not
cause any obvious problems. However, for users attempting to access SCIGN
data and logs and who wish to include these with data and log information
from other data centers, this becomes a thorny problem.  It can impact the
ability of other users to mix SCIGN data with other global or regional data
in a consistent or automated fashion.

The philosophy that has been adopted and adhered to by the IGS is that the
site log is the fundamental source of information on a GPS tracking
station. To promote uniformity in the use of GPS the site log format has
been standardized with obvious upgrades since at least 1991. It is a
convention that literally all GPS users adopt including campaign style GPS
observations. There is a discussion that has been initiated to further
develop the current site log format and it is expected that a number of
changes will be adopted later this year. In general this happens only after
agreement is achieved as to additional log content and revised format with
a broader based discussion. Then everyone converts to the new site log by a
specified time -- many of you may recall that the last major effort like
this occurred in 1996.

Currently, the IGSCB is attempting to ensure that all site logs are in
compliance, both in format and content, so that RINEX generation programs,
verification programs and SINEX templates can be easily generated and match
a common format, the content of which can be considered robust and
reliable.  This current exercise is sparked by the recently revised and
adopted antenna/receiver naming conventions which must be reflected in all
logs, RINEX files and SINEX files by July 4 for IGS processing upgrade.

I hope that this clarifies the current situation on the divergent file
format. Yehuda Bock, Angelyn Moore and myself have had a few constructive
telephone conversations as to how to resolve this situation. The SOPAC
groups effort is no doubt well intentioned and while the format may be more
machine readable for SCIGN implementation, it is incompatible with
practically every other reader in use. I have recommended that the SCIGN
logs should certainly match the current accepted log format until a new one
is adopted.

regards,

Ruth

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Ruth E. Neilan                    Telephone:     (818)-354-8330
Director, IGS Central Bureau      FAX:           (818)-393-6686
Jet Propulsion Laboratory         E-mail (IGS):  [email-masked]
MS 238-540                        E-mail:        [email-masked]
4800 Oak Grove Drive
Pasadena, CA 91109                IGS CBIS:  http://igscb.jpl.nasa.gov/

Secretary: Carol Lorre / tel:818-354-2077 /email:<carol.lorre @jpl.nasa.gov>
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[Mailed From: "Ruth E Neilan" <[email-masked]>]