Abstract: A 1-sigma pseudorange ground monitor (sigma monitor) is described. The sigma monitor calculates a weighted sum of squared deviations referred to as the discriminator for one or several reference receiver for a specific time period. The sigma monitor also calculates an alert threshold based on the chi-square or near chi-square probability distributions for one or several reference receivers and for the specific time period. The sigma monitor then compares the discriminator with the alert or alarm threshold. If the discriminator is greater than the alert or alarm threshold, an alert or alarm is issued and logged.

Abstract: A method and system pertaining to a dual antenna compensation algorithm is provided. A local area augmentation system may include a dual antenna system to receive signals from satellites. The system may switch between the antennas to receive signals, and the transition between the antennas should be seamless. Thus, phase variations between the antennas can be determined to correct for code phase variations, and hardware delays between the antennas can be determined to correct for delay differences in signals received from both antennas.

Abstract: A global positioning system for use with a plurality of transmitting satellites is disclosed wherein a full position solution is obtained from a number N of satellite transmissions and a plurality of sub-solutions each based on a different number (N−1) of satellite transmissions are obtained to determine if a satellite is faulty. A plurality of sub-sub-solutions is then obtained based on a different combination of N−2 satellites with each combination containing the satellites of different sub-solutions and excluding one other satellite in addition. An examination of the sub-sub-solutions provides an indication of which one of the satellites is the failed satellite.

Abstract: A global positioning system for use with a plurality of transmitting satellites is disclosed wherein a full position solution is obtained from a number N of satellite transmissions and a plurality of sub-solutions each based on a different number (N−1) of satellite transmissions are obtained to determine if a satellite is faulty. A plurality of sub-sub-solutions is then obtained based on a different combination of N−2 satellites with each combination containing the satellites of different sub-solutions and excluding one other satellite in addition. An examination of the sub-sub-solutions provides an indication of which one of the satellites is the failed satellite.