Data from the tracking stations whose positions are well known, are transmitted to the master station. Here, the orbits of the satellites are pre-calculated with corrections clock satellites. This data is then transmitted to satellites that form an essential part of the satellite message. Simultaneously visibility in two or more satellite stations ensure its continued pursuit even if one or more stations are not working properly.
At the same time, these observations provide training for single or double differences processing. Satellite datum is maintained by their ephemeris (satellite coordinates at a time), expressed in Terrestrial Reference System. There are a number of datum satellites reflecting various combinations of gravity field models, models of the rotation of the Earth or monitor stations coordinates are used. Selective Availability is a reduction technique willful positioning accuracy in real time, thus influencing mostly real – time navigation.
Decrease accuracy is achieved on the one hand by manipulating the satellite controlled phone tracker when errors occur controlled long and short in all sizes measurable and secondly through a distortion controlled ephemeris transmitted. The GPS receivers are key components of user segment and include GPS receiver itself, antenna, connector cable, defenders against reflected signals, cables, battery and antenna height measuring sticks.
The peripheral device user segment consists of computers that have implemented specific software, printers, diskettes. This peripheral is required for data processing and printing of a suitable form and for storing information.
The antenna receives signals from satellites visible physical reference point for the received signals being center stage, which may differ from the geometric center of the antenna. The phase center position depends on the construction of the antenna and varies depending on the direction of incidence of the satellite signals. Signals are transmitted to the amplifier signal and high frequency drive afterwards to the actual reception unit. Here signals are then identified and processed. In most receptors signals from a satellite are routed to a single channel reception. The entire reception facility is managed by a microprocessor that provides data storage and performs positioning calculations in real time.
Through a control unit, which essentially consists of a keyboard and a monitor, the user can communicate with the receiver. Measurements are recorded in the receiver’s memory and navigation messages. Power supply can be performed directly from the network or by external batteries. The aim is to determine signal processing during signal propagation through code C / A, decode and reconstruct the navigation signal carrier wave signal. If a receiver can record only the codes and messages navigation, navigation receivers are talking about.
For purposes geodetic receivers are needed in addition to recording the time of propagation and phase measurements allow the carrier wave. This can be done again differentiate between handsets operating on one frequency and receivers that operate on both frequencies.
Over time people have developed several ways of determining the position of a point and how to travel from one point to another. Initially sailors used for orientation angle measurements of the stars, sun and moon and after some laborious calculations determines the position of the observer. The 1920’s are witnessing the introduction of revolutionary technologies in navigation – radio navigation – which began allowing seafarers to determine the direction of the radio signal coming from stops located on the shore where the ships were within range of the transmitter.