A low-earth orbit (LEO) satellite includes a non-atomic clock configured to generate a clock signal, a navigation signal receiving and processing module, and a navigation signal generation and transmission module. The navigation signal receiving and processing module is configured to receive the clock signal from the non-atomic clock, receive first signaling including first timing data generated based on a high precision clock, and generate clock state data based on the clock signal and the first timing data. The navigation signal generation and transmission module is configured to receive the clock signal from the non-atomic clock, generate a navigation message that indicates the clock state data, generate a broadcast carrier signal by utilizing the clock signal, generate a navigation signal based on modulating the navigation message upon the broadcast carrier signal, and broadcast the navigation signal for receipt by at least one client device.

A method for monitoring an integrity of reference stations, having known and fixed coordinates, of a correction service system for a satellite-supported navigation system. A first group of the reference stations is operated to receive satellite signals of a plurality of satellites of the satellite-supported navigation system. It is provided that a) a first reference station is selected from the first group, and b) at least one first correction value is ascertained as a function of the satellite signals respectively received by the remaining reference stations of the first group, and c) the monitoring of the integrity is carried out in that first coordinates of the first reference station, determined using the satellite signals received by the first reference station and using the at least one first correction value, are compared with the known coordinates of the first reference station and checked for at least one first deviation.

A reinforcement information adjustment unit reduces an amount of information in reinforcement information by combining: update cycle adjustment processing to set an update cycle of the reinforcement information to be an integer multiple of a predetermined update cycle; geographic interval error value adjustment processing to reduce the number of geographic interval error values by selecting from among a plurality of the geographic interval error values each of which is an error at every predetermined geographic interval out of a plurality of error values, a geographic interval error value at every geographic interval that is an integer multiple of the predetermined geographic interval; and bit count adjustment processing to reduce a bit count of the error value for each error value. A reinforcement information output unit outputs, to an output destination, reinforcement information after being reduced in the amount of information by the reinforcement information adjustment unit.

A system to mitigate errors in GPS corrections and ephemeris uncertainty data broadcast to a vehicle is presented. The system includes reference receivers in a first ground subsystem and a processor. The processor: receives, from reference receivers in a wide area network of reference receivers, satellite measurement data for a first plurality of satellites and receives, from the reference receivers in the first ground subsystem, satellite measurement data and ephemeris data from a second plurality of satellites; evaluate the satellite measurement data to determine if the GPS corrections are degraded by a current ionosphere disturbance activity; determine a current quality metric of the ionosphere; adjust a Vertical Ionosphere Gradient standard deviation sigma-vig; evaluate the ephemeris data to determine if the GPS corrections provided to the vehicle are degraded by ephemeris errors; and establish ephemeris uncertainty to protect integrity based on the evaluation of the ephemeris data.

An error correcting location system includes a ground station with fixed reference coordinates. The ground station may receive satellite broadcast messages from a plurality of location system satellites. Further, the ground station may determine location coordinates based on the satellite broadcast messages, and compare the location coordinates to the fixed reference coordinates to determine a compensation value. In addition, the ground station may send the compensation value to location system devices. Upon receipt of the compensation value, the location system devices may utilize the compensation value to generate highly accurate location coordinates.

FAST provides a method of “bootstrapping” a pseudo-range (PR) stage and one or more carrier-phase (CP) stages to quickly produce a highly accurate, high integrity receiver-to-receiver lever arm survey based on differential GNSS processing. The lever arm estimates of a previous stage are used to resolve the carrier phase ambiguities of the next stage. The method can be integrated with the warm-up of the integrity monitors to reduce the entire survey and warm-up startup time to 90 minutes or less, which is critical for mobile and make shift and precision approach and (automated) landing operations.

A method for providing integrity information for checking atmospheric correction parameters for the correction of atmospheric disturbances for satellite navigation for a vehicle includes reading state signals relating to a state of an atmosphere between at least one satellite receiver and at least one satellite of the at least one satellite receiver. Each state signal represents certain state data that are transmitted between a satellite and a satellite receiver. The method further includes using at least one satellite signal and that are dependent on a state of the atmosphere between the satellite and the satellite receiver. The method further includes determining the integrity information using the state data. A variation of the state data against time is analyzed.

The interval between grid points to which transmitting positioning augmentation information is transmitted from a quasi-zenith satellite is set according to a fluctuation of an index value of an ionospheric state for each of a plurality of areas divided on the ground.

Differential ranging measurements are formed using first ranging measurements from reference GNSS receivers and second ranging measurements from GNSS receivers on a rover, the first and second ranging measurements received from a plurality of GNSS satellites. A main navigation solution and a main protection level (PL) set are computed based on the differential ranging measurements. Ionospheric threat scenarios associated with experiencing severe ionospheric gradients to one or more of the plurality of GNSS satellites are determined. A supplemental navigation solution and a corresponding supplemental PL set for each of the plurality of ionospheric threat scenarios are computed. A maximum PL set is selected based on the main PL set and the supplemental PL sets to form a final PL set that protects the main solution against nominal navigation threats and severe ionospheric threats.

Systems and methods for sharing convergence data between GNSS receivers are disclosed. Convergence data received at a GNSS receiver via a communication connection may be utilized to determine a position of the GNSS receiver.