OVERVIEW

SCIENCE

MISSIONS

NEWSROOM

EDUCATION

GALLERY

GPS - Global Positioning System

OSTM/Jason-2
The GPSP is a tracking system that receives dual-frequency navigation signals continuously and simultaneously from 16 GPS satellites to determine the exact position of a transmitter. The GPSP supports precise orbit determination by the Doris system. It also helps to improve gravity field models and provides data for satellite positioning accurate to about 50 meters and 50 nanoseconds. Additional information on the GPSP is available on the AVISO site.
Jason-1
The TRSR is a high performance GPS receiver designed to provide backup precise orbit determination for Jason-1. It will measure precise GPS "pseudorange" and continuous carrier phase data from up to 12 GPS satellites. The TRSR views the GPS satellites through an up-looking antenna which provides a nearly hemispherical field of view. There will be two complete redundant TRSR systems carried on Jason-1. Data from the BlackJack will be analyzed in post processing to produce continuous Jason-1 orbits. Additional information on the TRSR is available on the AVISO site.
TOPEX/Poseidon
The TOPEX/Poseidon GPS is based on a network of 21 military satellites in circular orbits 20,200 kilometers above the earth. These satellites broadcast signals that allow the GPS receiver aboard TOPEX/Poseidon to calculate the spacecraft's position in orbit. With augmented ground processing, this position is accurate to within 3 centimeters. The Global Positioning System antenna shown here is connected to a GPS Demonstration Receiver housed within the Instrument Module. The GPS receiver was included as an experiment because its use in Precision Orbit Determination for a spacecraft had never been demonstrated. The GPS receiver aboard TOPEX/Poseidon normally does not require commanding or special attention from the ground, and is always tracking. In the event that the receiver loses contact with the GPS satellites, ground-initiated commands are necessary to restart the on-board processor to enable it to re-acquire the GPS signal.