Survey Perspectives – September 2007

August 28, 2007  - By
Image: GPS World


I thought this would be a timely subject, since I’m heading off for two days of CGSIC/NAVCEN presentations before the ION GNSS 2007 conference starts on September 25. I’ll also be staying for the conference, and reporting back to you on what I hear there.

NAVCEN is an acronym for the U.S. Coast Guard Navigation Center. Its mission, according to its website, is to “provide cutting edge services for safe, secure, and efficient maritime transportation.”

CGSIC (est. 1987) is an acronym for the Civil GPS Service Interface Committee. It is the forum for the civil GPS community to communicate with GPS authorities, and vice versa. According to the CGSIC website, the committee “was established and chartered to identify civil GPS user needs in support of the Department of Transportation’s program to exchange information concerning GPS with the civil user community as part of the GPS ‘outreach’ program.”

The NAVCEN and CGSIC work hand in hand in facilitating communications for the civil GPS community; NAVCEN coordinates and manages the CGSIC. The NAVCEN site is one that you should have bookmarked in your web browser; there’s a lot of good information there. Here are some examples:

1. Notice Advisory to NAVSTAR Users (NANU) report: you can sign up for a daily e-mail that reports on the day-to-day status of the GPS constellation, or you can view the GPS constellation online. This is very helpful way to keep track of satellite outages that may affect your GPS field operations. For example, if a particular set of satellites is important to keep the PDOP low in your area, this is a good tool to let you know if one of those satellites is having a problem.

2. GPS Status Message (TIS-PF-NISWS) — This is daily GPS status report. If you subscribe to this mailing list, you will be sent an e-mail within 60 minutes of notification by the U.S. Air Force of a change to the constellation.

3. View and download the daily GPS almanac. (Both YUMA and SEM almanac formats — which most GPS mission planning software packages can handle — are available.)

4. View a list of DGPS and NDGPS sites broadcasting corrections. If you’re not sure you will be in range of a DGPS or NDGPS broadcasting station, this site provides details on each broadcasting station, including the precise location of the station, signal strength, expected coverage area and transmitting frequency.

The CGSIC coordinates some very informative meetings with very good information. Its membership is made up of U.S. and international private, government and industry user groups. The committee membership is free and open to anyone who is interested.

CGSIC meets at least once per year in conjunction with ION GNSS, which is usually held in September. However, there are subcommittee meetings throughout the year. There are four subcommittees:

The International Information Subcommittee last met in May 2007 in Geneva, Switzerland. Members are free to attend, but if you can’t, then you can download all of the presentations for a quick update. Going back and viewing previous years’ agendas and presentations is very informative.

The U.S. States and Localities Subcommittee last met in June 2007 in Bend, Oregon. I attended this meeting. There was good discussion on NDGPS, NGS initiatives and Network RTK. The Subcommittee also met in June 2007 in Minnesota. Notice the central theme of both meetings: NDGPS (but that’s another story).

The Survey, Mapping and Geosciences Subcommittee is a relatively new one. Not sure when they’ve last met, but I’ll get up to speed on that one at the CGSIC meeting. As for the Timing Subcommittee, I don’t stay current with that because it’s outside of the survey/mapping market.

Next week’s annual ION GNSS CGSIC meeting looks to be a good one: two days packed with all that a GPS connoisseur like me can handle. Day One is high-level information — policy stuff as well as program status reports on GPS, L1C, WAAS/LAAS and NDGPS.

Day Two is tough for me, because there are concurrent sessions by the three Subcommittees I follow:

  • GLONASS, Galileo, EGNOS, QZSS/MSAS, GBAS/GRAS, Beidou/Compass from the International Subcommittee.
  • HA-NDGPS, NDGPS and USCG DGPS from the U.S. States Subcommittee.
  • CORS/OPUS, various NGS initiatives, RTK Networks and Space weather from the Surveying, Mapping and Geosciences Subcommittee.

You can find a detailed look next week’s CGSIC agenda here.

This year, GPS World is doing something a little different, and I think you’ll like it. My e-newsletter colleagues and I will be your eyes and ears during the CGSIC and ION GNSS meetings; “We’re Bringing ION to you!” is the theme. We’ll be writing daily reports on subjects we think may interest you, and the website will be updated twice daily during the week.

If there’s something in particular you want me to check out while at the conference, fire off an e-mail to, and I’ll do my best to cover it.

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