GPS

A Key Note of GPS

Introduction GPS is a Global Positioning System based on satellite technology. The fundamental technique of GPS is to measure the ranges between the receiver and a few simultaneously observed satellites. The positions of the satellites are forecasted and broadcasted along with the GPS signal to the user. Through several known positions (of the satellites) and […]

A Brief Message About GLONASS (GPS)

GLONASS is a Global Navigation Satellite System (GNSS) managed by the Russian Space Forces and the system is operated by the Coordination Scientific Information Center (KNITs) of the Ministry of Defense of the Russian Federation. The system is comparable to the American Global Positioning System (GPS), and both systems share the same principles of the […]

Basic Information of Galileo (GPS)

Galileo is a Global Navigation Satellite System (GNSS) initiated by the European Union (EU) and the European Space Agency (ESA) for providing a highly accurate, guaranteed global positioning service under civilian control (cf., e.g., ESA homepage). As an independent navigation system, Galileo will meanwhile be interoperable with the two other global satellite navigation systems, GPS […]

A Combined Global Navigation Satellite System

The start of the Galileo system is a direct competition of the GPS and GLONASS systems. Without a doubt, it has a positive influence on the modernisation of the GPS system and the further development of the GLONASS system. Multiple navigation systems operating independently help increase the awareness and accuracy of the real time positioning […]

Geocentric Earth-Fixed Coordinate Systems (GPS)

GPS satellites are orbiting around the Earth with time. GPS surveys are made mostly on the Earth. To describe the GPS observation (distance) as a function of the GPS orbit (satellite position) and the measuring position (station location), suitable coordinate and time systems have to be defined. It is convenient to use the Earth-Centred Earth-Fixed […]

Coordinate System Transformations (GPS)

Any Cartesian coordinate system can be transformed to another Cartesian coordinate system through three succeeded rotations if their origins are the same and if they are both right-handed or left-handed coordinate systems. These three rotational matrices are: where a is the rotating angle, which has a positive sign for a counter-clockwise rotation as viewed from […]

Local Coordinate System (GPS)

The local left-handed Cartesian coordinate systemcan be defined by placing the origin to the local point, whose z’-axis is pointed to the vertical,x’-axis is directed to the north, andy’ is pointed to the east (cf., Fig. 2.5). The x’y’-plane is called the horizontal plane; the vertical is defined perpendicular to the ellipsoid. Fig. 2.5. Astronomical […]

Earth-Centred Inertial Coordinate System (GPS)

To describe the motion of the GPS satellites, an inertial coordinate system has to be defined. The motion of the satellites follows the Newtonian mechanics, and the Newtonian mechanics is valid and expressed in an inertial coordinate system. For reasons, the Conventional Celestial Reference Frame (CRF) is suitable for our purpose. The xy-plane of the […]

Geocentric Ecliptic Inertial Coordinate System (GPS)

As discussed above, ECI used the CIO pole in the space as the z-axis (through consideration of the polar motion, nutation and precession). If the ecliptic pole is used as the z-axis, then an ecliptic coordinate system is defined, and it may be called the Earth Centred Ecliptic Inertial (ECEI) coordinate system. ECEI places the […]

Time Systems (GPS)

Three time systems are used in satellite surveying. They are sidereal time, dynamic time and atomic time (cf., e.g., Hofman-Wellenhof et al. 1997; Leick 1995; McCarthy 1996; King et al. 1987). Sidereal time is a measure of the Earth’s rotation and is defined as the hour angle of the vernal equinox. If the measure is […]

← Previous Entries

Next Entries →