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.

A receiver device to receive an incoming radio frequency (RF) satellite signal from a satellite vehicle includes a processor and computer-readable storage media. The computer-readable storage media is communicably connected to the processor and has instructions stored thereon that, when executed by the processor, causes the processor to track the incoming RF satellite signal in code phase and carrier frequency, the incoming RF satellite signal having a primary pseudorandom (PRN) code and a secondary PRN code modulated thereon, generate an encoded sequence of dot product values of adjacent integrated in-phase (I) and quadrature-phase (Q) components of the incoming RF satellite signal, compare the encoded sequence with expected secondary code chip transitions, determine a secondary code phase for the secondary PRN code based on the comparison, and coherently integrate the secondary code phase with the incoming RF satellite signal to increase an integration interval.

A receiver for null steering in a navigation or positioning system includes a controlled reception pattern antenna (CRPA) comprising elements, a switch array coupled to the elements of the CRPA, and a receiver circuit. The receiver circuit is configured to receive an incoming radio frequency (RF) satellite signal from the switch array. The receiver circuit is configured to control the switch array to receive digitized samples, wherein each sample is in a respective time interval for each element of the CRPA elements. The receiver circuit is configured to apply a weight value to each sample and sum the samples to provide a null steering beam.

The presence or absence of a preamble is detected with accuracy in a reception. apparatus that receives a signal including a preamble.

A reception section receives a subframe including a subframe preamble and a message and a frame including a frame preamble. A processing section performs a process of detecting the presence or absence of the subframe preamble according to whether or not a given relation holds between a reception timing of the subframe preamble and a reception timing of the frame preamble. A message decoding section extracts the message from the subframe and decodes the message in a case where the presence of the subframe preamble is detected.

In conditions in which Global Navigation Satellite System (GNSS) signal spoofing is likely occurring, a GNSS receiver may be operated in a reduced operational state with respect to one or more GNSS bands that are likely being spoofed. According to embodiments, a reduced operational state with regard to a GNSS band may comprise performing one or more of the following functions with respect to that GNSS band: disabling data demodulation and decoding, disabling time setting (e.g., time of week (TOW), week number, etc.) disabling acquisition of unknown/not visible satellites, disabling satellite differences, disabling error recovery, reducing non-coherent integration time, and duty cycling the power for one or more receiver blocks associated with the GNSS band.

A Global Navigation Satellite System (GNSS) receiver demodulates code shift keying (CSK) data utilizing a binary search. The GNSS receiver receives a signal including a pseudorandom noise (PRN) code modulated by code shift keying (CSK) to represent a symbol (i.e., CSK modulated symbol). The GNSS receiver maintains a plurality of receiver codes each representing a different shift in chips to the PRN code. The GNSS receiver performs a linear combination of portions of the receiver codes. In an embodiment, the GNSS receiver compares correlation power level value for respective portions of the receiver codes to demodulate the CSK data. In a further embodiment, the GNSS receiver compares the correlation power level values for portions of receiver codes with power detection threshold values to demodulate the CSK data. In a further embodiment, the GNSS receiver utilizes signs of the correlation power level values to demodulate the CSK data.

A device for mitigating satellite navigation spoofing includes processing circuitry which detects correlation peaks for PRNs in a satellite navigation signal. The TOAs of subframes of navigation messages associated with each of correlation peaks are recorded and analyzed to determine if they fall within a specified time window. Based on the analysis, the correlation peaks are classified as legitimate or as spoofed. A correct geographic location is computed from the navigation data associated with the legitimate correlation peaks. Corresponding methods for mitigating satellite navigation spoofing may be embodied in a hardware-based GNSS receiver and in a software-based GNSS receiver.

A positioning receiver includes a processor configured to process a GNSS satellite transmitted navigation message received from at least one respective satellite vehicle to provide a navigation message data packet and to determine for each data bit of the navigation message data packet a respective confidence value; and to determine positioning data based on the data bits of the navigation message data packet and respective confidence values.

A GNSS (Global Navigation Satellite System) receiver apparatus includes a bank of correlators configured to receive in-phase and quadrature versions of a received signal. A code numerical controlled oscillator is configured to determine a code frequency. A GNSS pseudo random noise sequence generator is configured to generate a pseudo random noise sequence at the code frequency set by the code numerical controlled oscillator. A GNSS pseudo random noise delayed sequence generator includes a first shift register and a second shift register. Taps of the shift registers are selectable as a punctual replica, an early replica and a delayed replica of the pseudo random noise sequence. An enable circuit is configured to generate an enable signal coupled to an enable input of the flip-flops, the enable signal operating at a selectable enable frequency.

A method and apparatus are provided for demodulating a wireless signal modulated by phase-shift keying. The signal comprises a plurality of symbols. The method comprises: obtaining (310) a first sequence of samples based on the signal; converting (320) the first sequence of samples to a first sequence of frequency domain samples; selecting (330), as a decision variable, the sample that has the maximum magnitude among the first sequence of frequency domain samples; and identifying (340) a symbol or a symbol-transition based on the decision variable.