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Transmitted GPS Signals

The principle of position determination by GPS and the accuracy of the positions strongly depend on the nature of the signals. A variety of criteria was considered in the development of a suitable signal structure. In consequence the GPS signal is quite complex and...

Achievable Accuracy

A standard GPS receiver for civil use offers an accuracy down to a few meters. In praxis the number and geometry of the received satellites influences the accuracy considerably, and in daily use, accuracies of about 20 m can be expected. More sophisticated GPS Tracker...

Composition of the Data Signal

In addition to the C/A code navigational information is modulated into the L1 signal. The information consists of a 50 Hz signal and contains data like satellite orbits, clock corrections and other system parameters (information about the status of the satellites)....

Sources of Errors in GPS

Selective Availability The most relevant factor for the inaccuracy of the GPS tracking system is no longer an issue. On May 2, 2000 5:05 am (MEZ) the so-called selective availability (SA) was turned off. Selective availability is an artificial falsification of the...

WAAS and EGNOS

 The Logos of WAAS und EGNOS (From: FAA und ESA) Very much simplified, WAAS (Wide Area Augmentation System) is a satellite based differential GPS system (DGPS). The difference is, that no additional long-wave receiver is necessary to receive the correction data and...

History of NAVSTAR GPS

The GPS System was created and realized by the American Department of Defense (DOD) and was originally based on and run with 24 satellites (21 satellites being required and 3 satellites as replacement). Nowadays, about 30 active satellites orbit the earth in a...