Satellite echoing for geolocation and mitigation of Global Navigation Satellite System (GNSS) denial are provided herein, where an example method comprises: transmitting an initiated message to a communication satellite along a communication path that has a target device with an unknown distance to the communication satellite; receiving a returned message from the communication satellite over the communication path in response to the initiated message; determining a local time difference between the transmission time and the reception time; calculating a distance between the communication satellite and the target device, the distance calculated based on a portion of the determined time difference associated with only a single traversal of a portion of the communication path that is between the communication satellite and the target device; and performing one or more actions based on the distance between the communication satellite and the target device.

According to one or more of the embodiments herein, systems and techniques for multi-system-based detection and mitigation of Global Navigation Satellite System (GNSS) spoofing are provided. In one embodiment, a method comprises: obtaining a first location of an object from a primary location determination hardware system; obtaining a second location of the object from a secondary location determination hardware system; determining a distance difference between the first location and the second location; determining whether the distance difference between the first location and the second location is acceptable based on a threshold distance; and initiating one or more mitigation actions in response to the distance difference between the first location and the second location being unacceptable.

According to one or more of the embodiments herein, systems and techniques for multi-subset-based detection and mitigation of Global Navigation Satellite System (GNSS) spoofing are provided. In one embodiment, a method comprises: determining data associated with a distance between an object and each of a plurality of satellites to produce a corresponding plurality of datums; creating a plurality of different subsets of the datums; determining a plurality of possible computed solutions for the object based on the subsets of datums; determining, in response to the plurality of possible computed solutions falling within an acceptable proximity of each other, a trusted computed solution for the object based on the plurality of datums; and initiating, in response to at least one the plurality of possible computed solutions not falling within the acceptable proximity of each other of the plurality of possible computed solutions, one or more mitigation actions.

According to one or more of the embodiments herein, systems and techniques for satellite relaying for geolocation and mitigation of Global Navigation Satellite System (GNSS) denial are provided. In one embodiment, a method comprises: receiving, at a processing device from a communication satellite along a communication path, a message initiated by a transmitting device and indicating a transmission time, the communication path having a target device with an unknown distance to the communication satellite; determining a reception time upon receiving the message, (the processing device and the transmitting device have synchronized clocks); determining a time difference between the transmission time and the reception time; calculating a distance between the communication satellite and the target device based on a portion of the determined time difference associated with only traversal of a portion of the communication path between the communication satellite and the target device; and performing action(s) based on the distance.

A precise point position and real-time kinematic (PPP-RTK) positioning method, including: when direct emission signals broadcast by a multi-system navigation satellite and a low-earth-orbit constellation are detected, determining raw observation data (S11); receiving navigation satellite augmentation information broadcast by the low-earth-orbit constellation, and a low-earth-orbit satellite precise orbit and precise clock difference (S12); using the navigation satellite augmentation information, the low-earth-orbit satellite precise orbit and precise clock difference and the raw observation data for precise point positioning (S13); or when comprehensive ground-based augmentation error correction information is received, using the navigation satellite augmentation information, the low-earth-orbit satellite precise orbit and precise clock difference, the raw observation data and the comprehensive ground-based augmentation error correction information for precise point positioning of ground-based augmentation (S13′). The present application further relates to a precise point position and real-time kinematic (PPP-RTK) positioning device, a computer-readable storage medium and a processor.

The present application provides a fast and precise positioning method and system. The method includes: acquiring observation data of navigation satellites and LEO augmentation satellites at a current epoch; respectively acquiring navigation telegrams of the navigation satellites and the LEO augmentation satellites, and obtaining precise orbit and clock bias; correcting errors received in the positioning process according to the acquired navigation telegrams; normalizing by taking a type of satellite navigation system as reference to obtain unified linear observation equations, and calculating observation values of positioning and velocity measurement parameters; calculating estimated values of positioning and velocity measurement parameters at the current epoch through a state equation according to the calculated observation values of positioning and velocity measurement parameters and estimated values of positioning and velocity measurement parameters at the previous epoch; generating and saving positioning and velocity measurement results at the current epoch according to the estimated values of positioning and velocity measurement parameters.

A navigation system includes a receiver and a signal processor. The receiver is mounted on a second aircraft. The second aircraft is an acquisition target of location information. The receiver is configured to receive a navigation signal from each of three or more first aircrafts. The navigation signal includes the location information on a location of the corresponding first aircraft. The navigation signal is transmitted as a radio signal from a navigation apparatus mounted on each of the three or more first aircrafts. The signal processor is mounted on the second aircraft. The signal processor is configured to calculate a location of the second aircraft on the basis of the navigation signal.

In one implementation, first and second messages are received that include encoded position information for a transmitter. It is determined that both were received within some time of a previous message and that the second message was received within some time of the first message. A first location of the transmitter is determined based on the encoded position in the first message and the previously determined location. A second location of the transmitter is determined based on the encoded position in the second message and the previously determined location. It also is determined that the first and second locations are within a threshold distance. An updated second location of the transmitter is determined based on the encoded position information in the second message and the first location. A determination is made that the second location and the updated second location are within a threshold distance.

Provided is a method and apparatus for selecting an airborne position reference node. A weight center coordinate of the repeaters is calculated by using position coordinates of repeaters, a plane having a vector connecting the weight center coordinate and a position coordinate of a user as a normal vector is determined, and the position coordinates of the repeaters are orthographically projected onto the plane. A certain number of repeaters located farthest from the weight center coordinate of the repeaters are selected to be airborne position reference nodes, on the basis of the orthographically projected coordinates of the repeaters and the weight center coordinate.

A system and method are described for mitigating the jamming or spoofing of information that is used in a Global Navigation Satellite System (GNSS) geolocation system, such as the Global Positioning System (GPS). In an area of interest where accurate geolocation information is criticalfor example, at an airport, harbour, or other locations where accurate navigation is criticalseveral receiving stations having known and pre-determined geolocations are positioned. These receiving stations receive location signals from a constellation of geolocation satellites, and send the information about received signals to a central processing hub. The processing hub includes facilities to compare location information received by a particular receiving station and to determine whether the location information received by that receiving station from a particular satellite is consistent with known location information about that receiving station. In the event that there is a discrepancyas measured by filters designed to identify signals outside set thresholdsbetween the known location information and the received location information, the processing hub can send a warning signal that the location information from a satellite whose location information is found outside of thresholds should be ignored and that other positioning information should be used. The system and method may also be adapted to allow overriding of incorrect or undetectable location information with correct information so that an end user may use that information to correctly navigate within an area where jamming or spoofing may be occurring.