Abstract: Alerting a user of an integrity error in a global positioning system (GPS) signal transmitted from a transmitter in a global positioning system (GPS) satellite, by detecting an error in the global positioning system (GPS) signal, alerting the user of the error by shifting a phase of the global positioning system (GPS) signal from an initial value by a predetermined phase-shift amount, and returning, in the case that the detected error is corrected, the phase of the global positioning system (GPS) signal to the initial value. Preferably, the GPS signal is phase-shifted by the predetermined phase-shift amount using an alert timing pattern which indicates the level of detected error.

Abstract: The present invention is a system for providing GPS users with a high level of confidence in the integrity and accuracy of received GPS signals. The system provides a means for each GPS satellite itself to verify the accuracy and/or integrity of its own operations by calculations and processing internal to the GPS satellite and by crosslink communications with other GPS satellites in the GPS constellation. After a GPS satellite verifies the accuracy and/or integrity of its own signals, the GPS satellite transmits an integrity message to all GPS users in view of the satellite. The integrity message can alert GPS users to a loss of integrity or accuracy in the GPS signals. Alternatively, the integrity message can contain information to correct errors in the GPS signals. The integrity message can be incorporated into the existing GPS navigation message transmitted by GPS satellites, or the integrity message can be transmitted over a separate channel such as the planned L5 band channel.

Abstract: Intra-cluster and inter-cluster satellite network and communication method thereof. A satellite network includes a plurality of satellites disposed in one or a plurality of orbits, and a first wireless network formed between each of the plurality of satellites. The first wireless network includes a communication channel to transmit and receive spatial information between at least two of the plurality of satellites. Additionally, the satellite network includes a second wireless network formed between each of the plurality of satellites. The second wireless network includes a receiver, a routing system, and a transmitter.

Abstract: The present invention is a system for providing GPS users with a high level of confidence in the integrity and accuracy of received GPS signals. A waveform monitor allows the GPS satellite to verify the integrity of its transmitted signal by detecting its own transmitted waveform. The waveform monitor includes a receiver mounted in the GPS satellite. The receiver receives the GPS signal transmitted by the GPS satellite. The waveform monitor then compares the received GPS signal with a copy of what the GPS satellite intended to send which is stored in memory. The waveform monitor can compare the received digital navigation message with the copy stored in memory, and/or compare the received RF waveform with waveform data stored in memory. The waveform monitor thereby determines whether the transmitted signal has integrity. The GPS satellite then sends an integrity message to GPS users to inform the GPS users of the integrity of received GPS signals from that satellite.

Abstract: The present invention is a system for providing GPS users with a high level of confidence in the integrity and accuracy of received GPS signals. A beacon is located at a fixed point on the earth at a known location. The beacon emits a coded signal pulse having a precise RF waveform that is received by all GPS satellites in view of the beacon's location. The RF signal pulse is decoded and processed onboard each GPS satellite. The GPS satellite receives beacon position data from the other in-view GPS satellites via crosslinks. The GPS satellite compares the beacon position data with satellite position data such as Autonav data and thereby verifies the integrity of its own operation. The GPS satellite then sends an integrity message to GPS users to inform the GPS users of the integrity of received GPS signals from that satellite.

Abstract: The present invention is a system for providing GPS users with a high level of confidence in the integrity and accuracy of received GPS signals. The system provides a means for each GPS satellite itself to verify the accuracy and/or integrity of its own operations by calculations and processing internal to the GPS satellite and by crosslink communications with other GPS satellites in the GPS constellation. After a GPS satellite verifies the accuracy and/or integrity of its own signals, the GPS satellite transmits an integrity message to all GPS users in view of the satellite. The integrity message can alert GPS users to a loss of integrity or accuracy in the GPS signals. Alternatively, the integrity message can contain information to correct errors in the GPS signals. The integrity message can be incorporated into the existing GPS navigation message transmitted by GPS satellites, or the integrity message can be transmitted over a separate channel such as the planned L5 band channel.

Abstract: The present invention is a system for providing GPS users with a high level of confidence in the integrity and accuracy of received GPS signals. A first GPS satellite broadcasts a GPS navigation message to GPS users in view of the satellite. The first GPS satellite also sends a copy of the GPS navigation message to a second GPS satellite via an RF or optical crosslink. The second GPS satellite then determines the position and time of the first GPS satellite relative to the second GPS satellite based on the contents of the received GPS navigation message. The second GPS satellite compares this relative position and time to satellite position and time data stored in the second GPS satellite, such as ephemeris/almanac data received from a ground station or Autonav data. The second GPS satellite thereby checks whether the GPS navigation message received from the first GPS satellite has integrity. The second GPS satellite then sends an integrity message back to the first GPS satellite via a crosslink.