Satellite Navigation: Aviation GPS Systems – How They Work

Satellite Navigation is based on a global network of satellites that convey radio signals in medium earth orbit. Users of Satellite Navigation are most familiar with the 32 Global Positioning System satellites. The United States, who industrialised and operates GPS, and Russia, who established a similar system known as GLONASS, has offered free use of their respective systems to the international community. The International Civil Aviation Organization (otherwise known as ICAO), as well as other international user assemblies, have now accepted GPS and GLONASS as the core for an international civil satellite navigation capability known as the Global Navigation Satellite System (also referred to as GNSS).

The basic GPS service offers users with approximately 7.8 meter accurateness, 95% of the time, anywhere near or on the surface of the earth. To accomplish this, each of the 32 satellites emits signals to receivers that determine their location by computing the difference between the time that a signal is sent and the time it is received. GPS satellites carry atomic clocks that offer extremely accurate time. The time information is placed in the codes broadcast by the satellite so that a receiver can uninterruptedly determine the time the signal was broadcast. The signal contains data that a receiver uses to calculate the locations of the satellites and to make other adjustments needed for precise positioning. The receiver uses the time difference between the time of signal reception and the broadcast time to calculate the range, or distance, from the receiver to the satellite. The receiver must reason for proliferation delays, or decreases in the signal’s speed caused by the troposphere and the ionosphere. With information about the ranges to three satellites and the location of the satellite when the signal was sent, the receiver can calculate its own three-dimensional position. An atomic clock coordinated to GPS is required in order to compute ranges from these three signals. However, by taking a measurement from a fourth satellite, the receiver avoids the need for an atomic clock. Therefore, the receiver uses four satellites to calculate altitude, latitude, longitude, and time.

GPS’s have played a huge role in the avionics industry and the new innovations keep coming, and improve the field of work greatly. If you are in need of avionics equipment then please do not hesitate to contact Century Avionics for more information. Here you will find top quality avionics equipment that will ensure you have a safe and enjoyable flight.