GPS and satellite positioning, Galileo, Glonass, Compas Navigation Satellite System, RTK GPS surveying

Professional Surveyor March 2008 Volume 28 Number 3
Editor's Desk: GPS Is Everywhere
Tom Gibson, PE

On a weekend cross-country ski trip in early February, I ventured to Lapland Lake Nordic Vacation Center in New York's Adirondack Mountains, a complex with 50 kilometers of trails that wander in circuitous routes. I skied with my friend Pete, who carries a handheld GPS receiver strapped to his backpack. As we navigated the trail network, we would come to an occasional critical intersection, and he would say, "let me take a reading on this." Then at the end of the day, after he punched a button or two on the receiver, he announced that we had skied 12 miles.

This shows how prevalent GPS and satellite positioning have become. It permeates the surveying world more all the time and takes a parallel path in the civilian arena as well (more and more cars are equipped with GPS navigation functions). This issue focuses on satellite positioning just for this reason. Construction companies increasingly use machine control in their earthmoving operations. Aerial mapping companies are adopting airborne GPS, as we detailed in our Aerial Mapping 2008 supplement. Satellite constellations continue to increase in number and size, as Galileo and Glonass take shape, and we also hear about China's Compass Navigation Satellite System and one being built by India. RTK GPS surveying continues to see increased use as it becomes more affordable for surveyors, and base station networks proliferate around the world.

In January, I got a good glimpse of this when I attended the Pennsylvania Society of Land Surveyors' Surveyors Conference 2008. Brian Naberezny, a surveyor pursuing his Ph.D. at Penn State, taught a session entitled "Static GPS Post Processing." I thought it might be an esoteric class on math and software algorithms, but it turned out to be a complete historical overview of GPS and satellite positioning. Did you know it all started when the Russians launched Sputnik in 1957? Scientists at Johns Hopkins University noticed that radio signals received from the satellite varied based on its position. They measured Doppler shifts and used these to calculate Sputnik's position, theorizing that if the satellite position is known, they could compute positions on Earth.

But this issue also focuses on another area experiencing rapid technological advancement: subsurface surveying. Surveyors have long used magnetic locators to locate buried markers and underground pipelines as a means to an end in doing their job. Now, with the advent of ground-penetrating radar, they can take on the actual mapping of our underground infrastructure. This becomes more important as this expands while parts of existing infrastructure decay and need upgrading and replacement. As our infrastructure grows, it becomes more advantageous to map it in 3D and not just have plan-view layout drawings of it. GIS plays a huge role in creating a geospatial picture of this.

On a more immediate note, yours truly experienced a hard drive crash in his computer recently and lost all the data on it (it suffered what they call a head crash, and I joke that it wasn't wearing its helmet). I had backed up my document files but not my email. So if any of you have been corresponding with me by email, either about contributing a future story or to send me information on your company, please get back in touch with me so nothing falls though the cracks. And yes, I have since learned how to back up my email.