Disclosed herein are methods, devices, and systems for determining geographic location and time. In one embodiment, a radio and a processor configured for deriving a first signal tone originating from a first remote antenna located at a first location; deriving a second signal tone originating from a second remote antenna located at a second location; deriving a third signal tone originating from a third remote antenna located at a third location; determining a first frequency and a first phase at a first time of the first signal tone; determining a second frequency and a second phase at a second time of the second signal tone; and determining a third frequency and a third phase at a third time of the third signal tone. The method further includes determining a geographic location based on the first, second, and third frequencies; the first, second, and third phases; and the first, second, and third locations.

A method for generating a physical model of a path from GPS data. The method involves receiving GPS data defining a path from a GPS-enabled device and receiving a digital terrain model for an area that includes the path. An area of interest along the path is then identified and the GPS data associated with the area of interest is smoothed. The digital terrain model is sampled along the path and an elevation of the path is smoothed using a weighted average of the digital terrain model and the GPS data to create modified path data that is scaled to produce a first ribbon that is printed.

A method is for detecting loss-of-lock of a GNSS (Global Navigation Satellite System) signal tracking loop based on frequency compensation, comprising the following steps of: performing multi-channel frequency compensation on I-channel and Q-channel signals after down-conversion, pseudo-code stripping and integration clearing; then, performing coherent integration and non-coherent integration for a fixed time, and taking a maximum value of non-coherent integration results as a signal value; performing parabolic interpolation frequency identification, and taking an average value of the non-coherent integration results with the frequency differences of +/−50 Hz and +/−100 Hz as a noise value; and finally, calculating a ratio of the signal value to the noise value, and performing loss-of-lock detection with the ratio as a detection volume.

A navigation receiver, a navigation system and a method of time stamping asynchronous sensor measurements is provided. Sensor measurement data is received at a first port. A signal pulse is received at a second port. The signal pulse represents a time of measurement according to a first time domain of the received sensor measurement data. Based on the received signal pulse, a timestamp according to a second time domain is generated. The generated timestamp is associated in the second time domain with the received sensor measurement data.

A method of receiving two chip-by-chip multiplexed CSK signals (e.g., GNSS signals) and searching for a non-CSK signal with optimal performance at a given digit capacity of a sampling memory resided in parallel correlators. For CSK signals Prompt, Early and Late results for each of possible code shift are calculated as different sums of four punctured convolutions. Depending on configuration, the method allows to receive both multiplexed CSK signals with lesser quality or one of the CSK signals with better quality. The method can be implemented as an apparatus with four punctured correlators, a set of multipliers by 1 or 2.sup.N, another set of multipliers by 1 or 0, summers of four input to one result, a RAM, searchers of maximum, and conditional commutators.

A direct digital synthesis transmitter that uses a programmable digital circuit to generate a digital signal representing at least one radio frequency signal, the generated signal is filtered, amplified by an amplifier, and provided to a transmission antenna without upconversion. The transmitter generating the digital signal at a desired output frequency range such that a frequency upconverter is not needed to produce signals in the desired radio frequency range.

A system or method for generating or distributing GNSS corrections can include or operate to: generate a set of corrections based on satellite observations, wherein each correction of the set of corrections comprises an area associated with the correction, a tag, and correction data; update a set of stored corrections with the set of received corrections based on a tag associated with each correction of the set of stored corrections and the tag associated with each correction of the set of received corrections; and transmit stored corrections of the set of stored corrections to the GNSS receiver when the area associated with the stored corrections matches the locality of the GNSS receiver.

An apparatus that performs spoof detection of satellite signals based on clock information derived from the satellite signals. The apparatus may include a position, velocity, time (PVT) component that derives the clock information from the satellite signals and provides the clock information to a spoof detection mechanism. In some embodiments, the clock frequency estimate is modeled as a Wiener process.

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.

Aspects of the present disclosure relate to identifying points of interest by generating and storing virtual geofence information that is captured around a physical structure based in part on global positioning system (GPS) data from a plurality of devices that is then processed to identify GPS trajectory and kernel density estimation. Specifically, the techniques include receiving, at the network-based control computer, GPS data from a plurality of devices and grouping the GPS data from the plurality of devices to generate GPS trajectory information for each group of the plurality of devices. Based on the GPS trajectory information, the network-based control computer may calculate kernel density estimation and determine an isoline on a virtual map for the each group of the plurality of devices. By overlaying the isoline data on a geographic coordinate information of a physical structure, the network-based control computer may generate a virtual geofence around the physical structure and store, in a memory, geofence information for the facility.