Global Positioning System
Introduction: Global Positioning System, GPS
Summary of key findings: Google, ALZ.org, Wikipedia,
In a nutshell describing GPS - A navigational system involving satellites and computers that can
determine the latitude and longitude of a receiver on Earth by computing the time difference for
signals from different satellites to reach the receiver. Today, it is widely used by the civilian
public for both commercial and recreational use.
In addition to GPS, other systems are in use or under development. The Russian Global
Navigation Satellite System (GLONASS) was in use by only the Russian military, until it was
made fully available to civilians in 2007. The navigational signals transmitted by GPS satellites
encode a variety of information including satellite positions, the state of the internal clocks, and
the health of the network. These signals are transmitted on two separate carrier frequencies
that are common to all satellites in the network. Two different encodings are used: a public
encoding that enables lower resolution navigation, and an encrypted encoding used by the U.S.
military. So in 20 years you can just imagine where this will lead…
As of December 2013, there are 32 satellites in the GPS constellation. The additional satellites
improve the precision of GPS receiver calculations by providing redundant measurements. With
the increased number of satellites, the constellation was changed to a non-uniform arrangement.
Such an arrangement was shown to improve reliability and availability of the system, relative to
a uniform system, when multiple satellites fail. About nine satellites are visible from any point
on the ground at any one time, Ensuring considerable redundancy over the minimum four
satellites needed for a position.
Summary of key findings: Google, ALZ.org, Wikipedia,
In a nutshell describing GPS - A navigational system involving satellites and computers that can
determine the latitude and longitude of a receiver on Earth by computing the time difference for
signals from different satellites to reach the receiver. Today, it is widely used by the civilian
public for both commercial and recreational use.
In addition to GPS, other systems are in use or under development. The Russian Global
Navigation Satellite System (GLONASS) was in use by only the Russian military, until it was
made fully available to civilians in 2007. The navigational signals transmitted by GPS satellites
encode a variety of information including satellite positions, the state of the internal clocks, and
the health of the network. These signals are transmitted on two separate carrier frequencies
that are common to all satellites in the network. Two different encodings are used: a public
encoding that enables lower resolution navigation, and an encrypted encoding used by the U.S.
military. So in 20 years you can just imagine where this will lead…
As of December 2013, there are 32 satellites in the GPS constellation. The additional satellites
improve the precision of GPS receiver calculations by providing redundant measurements. With
the increased number of satellites, the constellation was changed to a non-uniform arrangement.
Such an arrangement was shown to improve reliability and availability of the system, relative to
a uniform system, when multiple satellites fail. About nine satellites are visible from any point
on the ground at any one time, Ensuring considerable redundancy over the minimum four
satellites needed for a position.