A time-free position determination of a roving receiver includes acquiring from a snapshot receiver in a cloud executing process, a snapshot position of the snapshot receiver received by the snapshot receiver for a single epoch from a constellation of global positioning satellites, the snapshot position including a multiplicity of time-free observables. The method additionally includes retrieving into the cloud executing process baseline position data for a fixed receiver received from the constellation and comprising time-referenced observables. Finally, the method includes compositing in the cloud executing process the time-free observables of the snapshot position with the time referenced observables of the baseline position data to produce time and position data for the snapshot receiver.

Systems, methods and apparatuses for generating long coherent integrations of received global navigation satellite system (GNSS) signals are described. One method includes generating coherent 1 second I/Q correlations by at least two stages of summation starting with 1 millisecond correlated I/Q signal samples. Intermediate stage coherent I/Q correlations may be modified based on, for example, lack of carrier phase lock and/or the carrier signal-to-noise density (C/N.sub.0). Such modifications include phase rotation. Energy/power amplitudes calculated from the coherent 1 second I/Q correlations may be used for improving multipath mitigation, the signal-to-noise ratio (SNR), and other GNSS receiver operations and functions.

Embodiments of the present invention provide a method, system and computer program product for bit transition enhanced direct position estimation (DPE) from global navigation satellite system (GNSS) signals and includes the reception in a GNSS receiver of signals from multiple, different satellites in multiple satellite constellations adapted for use with the GNSS. The method estimates the GNSS receiver parameters position, velocity, clock bias, clock drift, and optionally and if unknown, the receiver time. The method generates a model of the received GNSS signals that depends on the receiver parameters. Uniquely, the method includes the synchronization of both a primary code and also a secondary code in the received GNSS signal model, in addition to time delays, Doppler shifts, and other relevant parameters for positioning. Finally, if the secondary code of a particular signal is unknown, the method determines the combination of bit transitions that maximizes the optimization problem.

Examples for enhancing sensitivity to reflected GNSS signals are presented herein. An example may involve identifying, by a receiver, a particular positioning signal that reflected off a reflecting plane prior to reaching the receiver. The receiver may be in motion. The example may also involve determining a reflected satellite position for a satellite that transmitted the particular positioning signal based on identifying the particular positioning signal. The reflected satellite position may be determined by reflecting a position of the satellite about the reflecting plane. The example may also involve determining a direction vector to the reflected satellite position for the satellite and performing coherent integration over a threshold duration of time to increase a signal to noise ratio for the particular positioning signal based on the direction vector to the reflected satellite position.

A signal acquiring unit (3) performs signal detection and initial synchronization on an output from a RF frontend (2) by performing circular convolution operation using a first code replica corresponding to a case where a ranging code does not change in polarity and a second code replica corresponding to a case where a ranging code changes in polarity. A signal tracking unit (4) performs synchronization tracking using a result of signal acquisition output from the signal acquiring unit (3) as an initial value.

A tones processing system including an interference tone determination module (ITDM), an interference tone tracker module (ITTM) and an interference tone removal module (ITRM) is provided. The ITDM sequentially searches for one or more continuous wave interference (CWI) tones in N samples of intermediate frequency (IF) data within a programmable signal frequency band. The ITTM tracks the detected CWI tones. The ITRM removes the tracked CWI tones from the N samples of IF data using one or more interference tone removal units (ITRUs). Each of the ITRUs includes a second signal generator, a second mixer, a tone filter for suppressing the tracked CWI tones, and a quantizer for reducing the number of processing bits in a tone suppressed output signal. The ITRM performs frequency shift compensation and phase rotation compensation with reduced logic area and power consumption in the global navigation satellite system receiver.

A method and apparatus detects and estimates geo-observables of navigation signals employing civil formats with repeating baseband signal components, i.e., “pilot signals,” including true GNSS signals generated by satellite vehicles (SV’s) or ground beacons (pseudolites), and malicious GNSS signals, e.g., spoofers and repeaters. Multi-subband symbol-rate synchronous channelization can exploit the full substantive bandwidth of the GNSS signals with managed complexity in each subband. Spatial/polarization receivers can be provided to remove interference and geolocate non-GNSS jamming sources, as well as targeted GNSS spoofers that emulate GNSS signals. This can provide time-to-first-fix (TTFF) over much smaller time intervals than existing GNSS methods; can operate in the presence of signals with much wider disparity in received power than existing techniques; and can operate in the presence of arbitrary multipath

An aircraft and non-transitory computer-readable medium for detecting the spoofing of a signal from a satellite in orbit. A receiver on the aircraft to receive an apparent satellite signal. A computer for determining at least two characteristic signatures of the signal including a power level, and indicating the apparent satellite signal is a spoofed satellite signal.

In an embodiment, a method is provided. The method comprises selecting at least one set of line of sight (LOS) vectors oriented in one or more directions outward from a vehicle; determining at least one air data solution based on the at least one set of LOS vectors; adjusting at least one value of an air vector equation based on a predetermined quantity; upon adjusting the at least one value, then determining at least one modified air data solution, wherein the at least one modified air data solution is determined based on the at least one set of LOS vectors and the at least one value; and comparing a difference between the at least one air data solution and the at least one modified air data solution to a threshold value, wherein the threshold value is indicative of error with respect to the at least one set of LOS vectors.

Described herein is a method for improving the reception of a satellite navigation message divided in several pages and transmitted by one or several satellites. A satellite navigation message M of k pages is encoded inn pages, and any k retrieved pages from any satellite enables decoding of the original satellite navigation message M. An implementation of the method uses parallel block encoding for a binary erasure channel with high parity and zero overhead, where symbols at a fixed position of all pages are encoded in parallel into shorter codes. This method achieves full page interchangeability in the message transmission, optimizes message reception and reduces decoding cost.