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Chapter 4 Finding Your Location with the Global Positioning System
Smartphones will often have GPS capability as a standard function. Use of the
GPS is free for everyone and available worldwide, no matter what remote area
you find yourself lost in. So the first questions to ask are —who built this type
of geospatial technology and why?
Who Made GPS?
The acronym “GPS” seems to be in the common vocabulary to describe any
number of devices that use Global Positioning System technology for finding
a location, but it’s really an inaccurately used term. The term “GPS” originated
with the initial designers and developers of the setup, the U.S. Department of
Defense, and is part of the official name of the system, called NAVSTAR GPS.
Other countries besides the United States have developed or are currently engaged in developing systems like the NAVSTAR GPS, so when we’re describing “GPS,” we’re really discussing the United States system. Since the United
States isn’t the only nation with this technology, the more accurate way of
describing things would be to call GPS one type of Global Navigation Satellite
System (GNSS).
GPS isn’t the first satellite navigation system. During the 1960s, the U.S.
Navy used a system called Transit, which determined the location of sea- going
vessels with satellites. The drawback of Transit was that it didn’t provide continuous location information—you would have to wait a long time to get a
fix on your position rather than always knowing where you were. The Naval
Research Laboratory Timation program was another early satellite navigation
program of the 1960s, which used accurate clock timings for ground position
determination from orbit. The first GPS satellite was launched in 1978, and
the twenty-fourth GPS satellite was launched in 1993, completing an initial
full operating capacity of satellites of the system for use. Today, GPS is overseen and maintained by the 50th Space Wing, a division of the U.S. Air Force
headquartered at Schriever Air Force Base in Colorado.
What Does the Global Positioning System
Consist of?
Finding your position on the ground with GPS relies on three separate components, all operating together. They are as follows: a space segment, a control
segment, and a user segment.
Space Segment
There are numerous GPS satellites (also referred to as “SVs” or “Space
Vehicles”) orbiting Earth in fixed paths, which make up the space segment.
GPS satellites make two orbits around Earth every day (their orbit time is
actually about 11 hours and 58 minutes) at an altitude of 20,200 kilometers
(12,552 miles). The satellites are set in specific orbits, called a constellation,
NAVSTAR GPS the
United States Global
Positioning System.
GNSS the Global
Navigation Satellite
System, an overall term
for the technologies
using signals from
satellites for finding
locations on the Earth’s
surface.
space segment one
of the three segments
of GPS, consisting of
the satellites and the
signals being broadcast
from space.
constellation the
full complement of
satellites comprising a
GNSS.
Chapter 4 Finding Your Location with the Global Positioning System
Smartphones will often have GPS capability as a standard function. Use of the
GPS is free for everyone and available worldwide, no matter what remote area
you find yourself lost in. So the first questions to ask are —who built this type
of geospatial technology and why?
Who Made GPS?
The acronym “GPS” seems to be in the common vocabulary to describe any
number of devices that use Global Positioning System technology for finding
a location, but it’s really an inaccurately used term. The term “GPS” originated
with the initial designers and developers of the setup, the U.S. Department of
Defense, and is part of the official name of the system, called NAVSTAR GPS.
Other countries besides the United States have developed or are currently engaged in developing systems like the NAVSTAR GPS, so when we’re describing “GPS,” we’re really discussing the United States system. Since the United
States isn’t the only nation with this technology, the more accurate way of
describing things would be to call GPS one type of Global Navigation Satellite
System (GNSS).
GPS isn’t the first satellite navigation system. During the 1960s, the U.S.
Navy used a system called Transit, which determined the location of sea- going
vessels with satellites. The drawback of Transit was that it didn’t provide continuous location information—you would have to wait a long time to get a
fix on your position rather than always knowing where you were. The Naval
Research Laboratory Timation program was another early satellite navigation
program of the 1960s, which used accurate clock timings for ground position
determination from orbit. The first GPS satellite was launched in 1978, and
the twenty-fourth GPS satellite was launched in 1993, completing an initial
full operating capacity of satellites of the system for use. Today, GPS is overseen and maintained by the 50th Space Wing, a division of the U.S. Air Force
headquartered at Schriever Air Force Base in Colorado.
What Does the Global Positioning System
Consist of?
Finding your position on the ground with GPS relies on three separate components, all operating together. They are as follows: a space segment, a control
segment, and a user segment.
Space Segment
There are numerous GPS satellites (also referred to as “SVs” or “Space
Vehicles”) orbiting Earth in fixed paths, which make up the space segment.
GPS satellites make two orbits around Earth every day (their orbit time is
actually about 11 hours and 58 minutes) at an altitude of 20,200 kilometers
(12,552 miles). The satellites are set in specific orbits, called a constellation,
NAVSTAR GPS the
United States Global
Positioning System.
GNSS the Global
Navigation Satellite
System, an overall term
for the technologies
using signals from
satellites for finding
locations on the Earth’s
surface.
space segment one
of the three segments
of GPS, consisting of
the satellites and the
signals being broadcast
from space.
constellation the
full complement of
satellites comprising a
GNSS.