Definitions of GPS System

Definitions of GPS System

Professional GPS station and receiver for centimeter accuracy.

According to abbreviationfinder, GPS is evolving towards a more robust system (GPS III), with greater availability and that reduces the complexity of GPS augmentations. Some of the planned enhancements include:

  • Incorporation of a new signal in L2 for civil use.
  • Adding a third civil signal (L5): 1176.45 MHz
  • Protection and availability of one of the two new signals for Security for Life (SOL) services.
  • Improved signal structure.
  • Increase in signal power (L5 will have a power level of –154 dB).
  • Improved accuracy (1 – 5 m).
  • Increase in the number of monitoring stations: 12 (double)
  • Enable better interoperability with the Galileo L1 frequency

The GPS III program pursues the goal of ensuring that GPS will meet anticipated military and civilian requirements for the next 30 years. This program is being developed to use a 3-stage approach (one of the transition stages is GPS II); very flexible, allows future changes and reduces risks. The development of GPS II satellites began in 2005, and the first of these will be available for launch in 2012, with the goal of achieving the full transition from GPS III in 2017. The challenges are as follows:

  • Represent the requirements of users, both civil and military, in terms of GPS.
  • Limit GPS III requirements within operational objectives.
  • Provide flexibility to allow future changes to meet user requirements through 2030.
  • Provide robustness for the growing reliance on precise time and position determination as an international service.

The system has evolved and new positioning systems have been derived from it. IPS-2 refers to the Inertial Positioning System, an inertial positioning system, a data capture system that allows the user to perform measurements in real time and in motion, the so-called Mobile Mapping. This system obtains 3D mobile cartography based on a device that collects a laser scanner, an inertial sensor, GNSS system and an odometer on board a vehicle. Great accuracies are achieved, thanks to the three positioning technologies: IMU + GNSS + odometer, which working at the same time give the option of measuring even in areas where the satellite signal is not good.


Earth in Space

The galaxy or the Milky Way, is simply one more in the vastness of the Universe. Our closest star, the Sun, is just one of the billions of stars in the Milky Way. The planet Earth is one of 9 satellites that give laps around the sun in an elliptical orbit. These planets, from the closest to the furthest from the Sun, are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. The rules that govern the motion of these solar satellites (the planets) are studied in the discipline of Celestial Mechanics, and were discovered by exceptional scientists such as Johannes Kepler and Isaac Newton hundreds of years ago.

The movement of the 9 solar planets is like a fascinating clockwork machinery. The force that holds them together and determines their relative movements is ” gravity.” The closer a planet is to the Sun, the gravitational force it feels is greater and it must move faster in its orbit to avoid falling into the Sun. For example, Earth, located about 150,000,000 km from the Sun, it travels in its orbit at an average speed of about 30 kilometers per second and completes one revolution around the Sun in one year.

Several planets, in turn, have one or more satellites orbiting them. For example, the only natural satellite of the Earth, the Moon, is located at an average distance of about 385,000 kilometers from the Earth and makes a complete revolution around it in about 29 days. The different positions of the Moon with respect to the Earth determine its four phases: full moon, new moon, first quarter and last quarter. The definition of satellite is therefore quite easy to guess. It is simply one body orbiting another. Gravity is the force of attraction that makes possible the relative movement of the orbits described by the satellites.

Satellites orbiting the Earth

The detailed knowledge of the rules of Celestial Mechanics and the study of the movement of natural satellites has allowed scientists to design and put into orbit artificial satellites around the Earth and Mars (like, for example, the Viking). Powerful rockets are used to launch satellites into space. If the launch speed is very low, the satellite will fall back to Earth attracted by the force of gravity., in the same way that when throwing a stone it falls back to the earth’s surface. On the other hand, if the launch speed is excessively high, the Earth’s gravitational force will not be enough to keep the satellite in orbit and it will escape into space. Today there are many artificial satellites orbiting the Earth with different purposes:

  • Telecommunications
  • Weather forecast
  • Military applications
  • Scientific investigation
  • Geophysics

The orbits of some satellites are synchronized with the rotation period of the Earth. If their speeds coincide exactly with that of the Earth’s rotation, the satellites are called geostationary and they always remain at the same point in the sky with respect to the Earth. If the speeds are different from the Earth’s rotation, then the satellites “rise” and “set” at different times, just like the Moon. Some go off and on multiple times throughout a day. Some form of communication is needed to send orders and receive responses from satellites to Earth. Although there are many ways to do this, the basic alphabet of communication consists of radio waves., such as those used to broadcast television and radio programs.

GPS System

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