The satellites continuously transmit radio signals at a certain frequency and with a specific code. A satellite receiver can receive the codes from four or more satellites and compare these with the possible code sequences. Since the time structure of the various satellite codes is known, the receiver is then able to calculate which satellites it is receiving information from and when they transmitted their signals.
The receiver can calculate how long the radio signal took to reach the receiver from the satellite by comparing its own time with the time when the code was transmitted. Accurate clocks are required to measure the delay time of the signals and obtain a highly accurate position.

For this reason, the satellites are equipped with atomic clocks. The cheap satellite receivers used by end consumers do not have to be fitted with atomic clocks because these units correct their time automatically based on the satellite data.

This technology, which has now been in use for around 20 years, was developed for military requirements. The benefits of this system for civilian applications were recognized and suitable applications were developed.

Due to the fact that the existing systems are primarily oriented towards military requirements, they do not guarantee the signal accuracy and availability required by end customers for civilian applications. This is why a number of potential applications (especially in safety-critical fields) have not yet been fully exploited to date.

The development of the European satellite navigation system "Galileo", which is scheduled to become fully operational from 2013, is expected to give an important boost to the development of civilian applications.

Applications are expected to be developed in the fields of power supply, health, logistics, public and private safety, production technology, rescue services, rail transport, tourism, environmental protection, traffic, the insurance sector and science.