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The Cedar Mesa Project

Global Positioning Systems

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"The ultimate achievement of humankind's urge to know where he or she is at, at extraordinarily high levels of precision, is manifested in today's Global Positioning System. Those who have grown up with Star Trek may find the idea of simply flipping open a small device to locate where you are on the planet something of a yawner. The fact is this technology represents a true revolution, comparable in scope to the invention of the accurate ship-board clock that heralded the age of global circumnavigation of the 1700's."
Gregory T. Finch, "Understanding the GPS", GeoResearch Inc., 1996.

Global Positioning Systems

Directory to the Global Positioning System page -

GPS - An Opportunity and a Responsibility
in Geologically, Archaeologically and Culturally Sensitive Areas

The Global Positioning System (GPS), with its seemingly miraculous capability of providing instantaneous location and tracking information anywhere on earth, offers a fantastic opportunity to explore our world. This has been especially the case for exploring the High Desert areas where many of the cultural artifacts, such as remnants of Anasazi dwellings, petroglyphs, and pictographs, from the early Native Americans are found.

But this easy access has become a problem. Many of these artifacts, which have survived in the ravages of hundreds of years of being exposed to the elements, are becoming degraded by the very fact that there is such easy human access to them. And they - with their treasures of information and heritage - are being lost to us and to future generations because of this easy access.

When you use this technology, please bear in mind that the artifacts, be they from the mountain building processes that sculpted this beauty, to the long history of the early Native Americans struggling to survive in what to them was probably a very challenging environment, and artifacts from the early American explorers and settlers, are still very important - to us for the information they contain about these early people and their efforts to live here; they are important to us because of their cultural and spiritual significance and relevance to many of the Native Americans who live in the area and regard some of these artifacts as an important part of their history, a perspective which should be respected.

It is pertinent to remind readers that there are explicit regulations that limit public disclosure of the locations or character of historic resources when it is determined that the disclosure of such information may create a substantial risk of harm, theft, or destruction to such resources or to the areas or place where such resources are located. One example of this is the State of Colorado's "Dissemination of Information - Policy/Procedures, publication 1333" as managed by the State Office of Archaeology and Historic Preservation.

The State of Utah has similar regulations about this area - Regulatory Assistance for Federal, State and Local Access - http://www.dced.state.ut.us/history/Services/lchome.html

Furthermore,these regulations are enabled by an explicit exclusion in the Freedom of Information Act which reads as follows -

Excerpt from The Freedom of Information Act - Section 552 (b)

This section does not apply to matters that are-

(3) specifically exempted from disclosure by statute (other than section 552b of this title), provided that such statute:

(A) requires that the matters be withheld from the public in such a manner as to leave no discretion on the issue,

(B) establishes particular criteria for withholding or refers to particular types of matters to be withheld;

Other considerations -

"The authority to restrict information about historic and archaeological resources applies to inventories that receive Federal assistance under the authority of the NHPA or Executive Order 11593. Such inventories include the survey and inventory data of all State Historic Preservation Offices, Federal agencies, and Certified Local Governments." National Register Bulletin 29.

To this end, please use the easy access to these geologically, culturally and archaeologically sensitive discoveries as an opportunity to enrichen your life experiences and not to degrade them for others to enjoy the same.

Consider the simple "common knowledge" considerations mentioned in the following pages within the context of this modern technology which can make the exploration experience much more enjoyable for yourself and for others who will be coming later -

Introduction to the GPS System

The Global Positioning System is a fleet of satellites (currently some 27 are operational) that were put up by and are maintained by the United States military, originally for military defense positional location purposes.

As of May 1, 2000, the "Selective Availability" feature that degraded the signals for civilian use was turned off. Which now means that most civilian GPS receivers should now display longitude and longitude position to an accuracy of less than 12 meters (35 feet) greater than 95 percent, and less than 6 meters (20 feet) greater than some 50 percent of the time, anywhere on earth.

Height accuracy is about two-thirds that for horizontal - some 18 meters (55 feet).

The operational GPS system aims for 24 satellites in orbit at all times, with 21 fully functioning and three available as backups.

These one-thousand kilogram (two-thousand pounds) satellites are in six orbital planes that are inclined 55 degrees to the equator and at an altitude of 20,220 km (10,900 miles) - an orbit takes 12 hours. Three or four satellites are in each orbital path. The design goal is for five to eight satellites to be always visible from any point on earth at all times.

The satellite carrier signals are transmitted at carrier frequencies of 1575.42 (L1 band) and 1227.62 (L2 band) Mhz. Which means the signals can be attenuated by some building roofs and rock overhangs, or even your hand, to the extent that the receiver can loose the signals.

For an extensive discussion of this system, see "Global Postioning System Overview," by Peter Dana, The Geographer's Craft Project, at the University of Colorado.

GPS Lingo and Buzzwords

There are a lot of cryptic military-type abbreviations in this field. A few are -

Links to GPS Information

The following links will take you into several GPS support areas for much more information about this system -

Schriever Air Force Base (in Colorado Springs, Colorado) is the management center for GPS. This site has current satellite status, links to may other resources and is the primary source of military support information. (Be warned this site posts a separate "Notice and Consent" natter page which comes up in a separate browser window - which must be explicitly Exited before you can do much else!)

Some fact sheets about GPS from Schriever Air Force Base site -

  • http://www.schriever.af.mil/fact_sheets/gps/index.htm

    The Coast Guard makes extensive use of GPS. Here is the Coast Guard's Navigation Center GPS Home Page with internal links to several areas of interest: Status, Alamanacs, User Input. Issues, Interrupts, General Information, GPS Management, NGS Data, Archives, Policy Notes, FAQ, Links, Year 2000 -

    A press release about Selective Availability being turned off is available from

    You can subscribe to an emailed report on current status of the GPS systemthat is sent to you every day:

    An excellent overview and introduction plus in depth discussion about GPS and an extensive list of references to other sites for even further information is -

    An Animated, but educational, tutorial about GPS is available from Trimble Navigation -

    The following is billed as the Navstar Home Page; and has links to much more GPS information -

    Examples from NASA about GPS applications around the world -

    An Interagency GPS Executive Board has several interesting fact sheet pages available -

    More GPS information -

    A commercial site that offers a wide variety of GPS software for most recivers -

    An Introduction to the Global Positioning System, which includes an explanation of how GPS works -

    GPS Equipment Manufacturers

    Here is a list of links to most manufacturers of Global Positioning Systems -

    The following link was originally developed for the Y2K situation - note that the GPS satellites had a clock counter rollover on August 22, 1999 - (when taxicabs in Tokyo, Japan were getting lost!) and may still be available for general information -

    GPS Mathematics

    Aviation Formulary Support Information. Contains some of the detailed mathematical formulas that are used by the GPS receivers for calculating positions -

    Literature on GPS

    Some books that explain the GPS system are -

    A Comprehensive Guide to Land Navigation with GPS
    Noel J. Hochkiss, 1994
    Basic introduction to using GPS for orienteering.

    Differential GPS Explained
    Jeff Hurn, 1993
    Trimble Navigation
    Basic introduction to differential navigation

    GPS, The Guide to the Next Utility
    Jeff Hurn, 1989
    Trimble Navigation
    Beginner's book to GPS

    GPS Surveyor's Field Guide,
    A Field Guidebook for Dynamic Surveying
    Trimble Navigation, 1991

    GPS, Theory and Practice
    B. Hoffman-Wellenhof, et. al., 1994
    Technical guide to most questions

    Guide to GPS Positioning
    David Wells, 1987
    Canadian GPS Associates
    Comprehensive, fairly technical, but dated

    The Global Positioning System and GIS, An Introduction
    Micheal Kennedy, 1996
    Trimble Navigation
    Detailed manual for the Trimble receivers

    Understanding the NAVSTAR GPS ...
    Tom Logsdon, 1995
    Comprehensive, informative general coverage

    Understanding the GPS
    Gregory T. Finch, 1996
    GeoResearch, Inc.
    Comprehensive explanation and definitions of the system

    An especially interesting and detailed article on the global positioning system is the following -

    "You are Here!"
    by William Walling
    Analog Science Fiction and Fact magazine
    October 1999 issue; page 38.

    The author goes into considerable detail about the methodology (and the several levels of approximation that take place before you are given the final display) of deriving the location, and presents some interesting examples of some GPS applications the original planners probably never thought of.

    Be aware that listing the address of a web site in the Cedar Mesa Project web site does not imply endorsement or condonement of the organization, its views or its products.

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