Abstract: An efficient covariance matrix computation method is disclosed in connection with certain GNSS applications, including ARAIM and geometry screening. The system and method of the present application enable computation of multiple covariance matrices with substantially greater efficiency than previous approaches, including the rank-one update formula. For example, the system and method of the present application advantageously involves substantially fewer and simpler arithmetic operations than previous approaches. In addition, unlike the rank-one update formula, the system and method of the present application can be used to compute the subsolution in which all the satellites of a given constellation are removed.

Abstract: A global navigation satellite system (GNSS) receiver including a processing device configured to: group GNSS satellites in view of the GNSS receiver into subsets based on relative geometries of the GNSS satellites relative to the GNSS receiver, wherein a GNSS satellite of the GNSS satellites is included in at most one subset of the subsets, wherein each subset of the subsets includes at least one GNSS satellite of the GNSS satellites and less than all GNSS satellites of the GNSS satellites, and wherein at least one subset includes more than one GNSS satellite; calculate a plurality of navigation sub-solutions based on data received at the GNSS receiver from the GNSS satellites using at least one GNSS antenna, wherein each navigation sub-solution of the navigation sub-solutions is calculated with at least one different subset of the subsets excluded; and calculate a protection level based on the navigation sub-solutions.

Abstract: A global navigation satellite system (GNSS) receiver includes radio frequency front end and digital processing functionality. Radio frequency front end includes radio frequency input; first variable gain amplifier adjusts first gain of first frequency range of first analog GNSS signal received from radio frequency input by first amount; and second variable gain amplifier adjusts second gain of second frequency range of second analog global navigation satellite system signal received from radio frequency input by second amount. Digital processing functionality compares first amount of adjustment of first gain of first frequency range with second amount of adjustment of second gain of second frequency range; and detects first interference signal present in first frequency range or second frequency range when first amount of adjustment of the first gain of first frequency range differs from second amount of adjustment of second gain of second frequency range by more than first threshold amount.

Abstract: Systems and methods for a scanning correlator for global navigation satellite system signal tracking are provided. In one embodiment, a method for Global Navigation Satellite System (GNSS) receiver tracking comprises: receiving a GNSS navigation signal; generating a local Pseudo Random Noise (PRN) sequence; sampling the GNSS navigation signal over a plurality of integration periods to produce a plurality of scanning values, wherein each scanning value has a respective time offset such that at least one first time offset is not equal to at least one second time offset; estimating at least two points of an autocorrelation function for the GNSS navigation signal based on the plurality of scanning values; and calculating an alignment between the GNSS signal and the local PRN sequence based on the autocorrelation function estimate.

Abstract: Systems and methods for a scanning correlator for global navigation satellite system signal tracking are provided. In one embodiment, a method for Global Navigation Satellite System (GNSS) receiver tracking comprises: receiving a GNSS navigation signal; generating a local Pseudo Random Noise (PRN) sequence; sampling the GNSS navigation signal over a plurality of integration periods to produce a plurality of scanning values, wherein each scanning value has a respective time offset such that at least one first time offset is not equal to at least one second time offset; estimating at least two points of an autocorrelation function for the GNSS navigation signal based on the plurality of scanning values; and calculating an alignment between the GNSS signal and the local PRN sequence based on the autocorrelation function estimate.

Abstract: Embodiments for satellite subset selection for use in monitoring the integrity of computed navigation solutions are disclosed. In one embodiment, a Global Navigation Satellite System (GNSS) receiver comprises: a processing device configured to: group a plurality of satellites in view of the GNSS receiver into a plurality of subsets, wherein a satellite of the plurality of satellites is included in at most one subset of the plurality of subsets, wherein each subset of the plurality of subsets includes at least one satellite of the plurality of satellites and less than all satellites of the plurality of satellites, and wherein at least one subset includes more than one satellite; calculate a plurality of navigation sub-solutions, wherein each navigation sub-solution of the plurality of navigation sub-solutions is calculated with at least one different subset of the plurality of subsets excluded; and calculate a protection level.

Abstract: A global navigation satellite system (GNSS) receiver includes radio frequency front end and digital processing functionality. Radio frequency front end includes radio frequency input; first variable gain amplifier adjusts first gain of first frequency range of first analog GNSS signal received from radio frequency input by first amount; and second variable gain amplifier adjusts second gain of second frequency range of second analog global navigation satellite system signal received from radio frequency input by second amount. Digital processing functionality compares first amount of adjustment of first gain of first frequency range with second amount of adjustment of second gain of second frequency range; and detects first interference signal present in first frequency range or second frequency range when first amount of adjustment of the first gain of first frequency range differs from second amount of adjustment of second gain of second frequency range by more than first threshold amount.

Abstract: A global navigation satellite system (GNSS) receiver includes a processor to determine whether a first satellite is in view of GNSS receiver; whether a second satellite is in view of GNSS receiver when first satellite is in view of GNSS receiver; and whether a third satellite is in view of GNSS receiver when first satellite is not in view of GNSS receiver. Second satellite was previously determined more likely to be in view when first satellite is in view based on a first average distance between first satellite and second satellite based on a first orbit of first satellite and a second orbit of second satellite. Third satellite was previously determined more likely to be in view when first satellite is not in view based on a second average distance between first satellite and third satellite based on first orbit of first satellite and a third orbit of third satellite.

Abstract: Systems and methods for satellite signal tracking are provided. In one embodiment, a GNSS tracking system comprises: a carrier demodulator that receives a navigation signal including pilot and data signal components; a correlator block that implements early, prompt and late correlators, generates prompt values from the pilot signal, and generates early and late values from the data signal; a carrier tracking loop that generates a reference signal using the prompt values, and outputs the reference signal to the carrier demodulator; a code tracking loop that outputs a pilot signal local replica to the prompt correlator and a data signal local replica to the early and late correlators, wherein a chip rate for the local replicas is adjusted by the code tracking loop as a function of the early and late values; and a symbol demodulator that extracts navigation data from the data signal component using the early and late values.