It is provided of a system capable of estimating a current position of a terminal apparatus, even if a terminal apparatus for mobile communication is in a condition of non-receiving or inability to receive GNSS signals. A radio relay apparatus, in which a relay station mounted on a drone, transmits radio waves from a directional antenna toward the ground while flying in an upper airspace above a target area on the ground, and transmits position information on its own apparatus obtained based on the GNSS signal, to an information processing apparatus. The terminal apparatus measures a reception power or a reception quality of radio waves transmitted from the radio relay apparatus, and transmits reception measurement information regarding the measurement result of the reception power or the reception quality, to the information processing apparatus. The information processing apparatus estimates the position of the terminal apparatus in the target area, based on the position information from the radio relay apparatus received in a flight time period during which the radio relay apparatus flies in the upper airspace above the target area and the reception measurement information from the terminal apparatus. The information processing apparatus may estimate the position where the reception power or the reception quality from the terminal apparatus is maximum, as the position of the terminal apparatus.

A method and devices are disclosed that locate a target station moving at a constant velocity. A method and devices are disclosed for producing an RTT vector that is based upon the changes in position of the airborne measuring station position and the relative change in position of the target station. In one embodiment, the target station is an access point or station conforming to the IEEE 802.11 Standard and the airborne measuring station may also be a device that conforms to the IEEE 802.11 Standard.

A computer-implemented method is for detecting Global Navigation Satellite System (GNSS) signal spoofing. The method includes storing sample sequences of the predictable part and of the unpredictable part of a GNSS signal at a GNSS receiver. The predictable part includes predictable bits and the unpredictable part includes unpredictable bits. The value of the unpredictable bits from which the unpredictable sample sequences are extracted is verified. A first and a second partial correlation between the unpredictable, respectively predictable, sample sequences and a locally stored GNSS signal replica are computed. A predefined metric from the complex valued partial correlations is calculated. The predefined metric is compared with a predefined threshold value. In a zero-delay replay attack, the spoofer estimates the unpredictable bits introduced by a GNSS authentication protocol and introduces distortion into the signal. Detecting this distortion indicates whether the signal under analysis is being spoofed or is authentic.

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.

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 preprocessing system includes a first port, where one end of the first port is coupled to a first switch, and the other end of the first port is suspended, where the first switch has a connecting end configured to couple to a first interface and is configured to connect a filter and the first interface, a second port configured to receive a first signal or a second signal, where the filter is configured to filter the first signal to obtain a first positioning signal and a second positioning signal, provide the first positioning signal for the first switch, and provide the second positioning signal for a second interface of a global navigation satellite system (GNSS) chip to adapt to a plurality of antenna configuration types and to achieve universality.

A platform with a signal generation unit and a transmitting unit. The signal generation unit is adapted to generate a spreading code sequence. The spreading code sequence has a reference chip with a rising edge and a falling edge. The signal generation unit is adapted to adjust the spreading code sequence to ensure that the rising edge or the falling edge of the reference chip arrives at a Virtual Timing Reference Station, VTRS, on a predetermined time (t.sub.ref,VTRS). The transmitting unit is adapted to engage with the signal generation unit and adapted to transmit the spreading code sequence. Further, a user device for receiving the transmitted spreading code sequence.

The embodiments described herein provide ranging and location determination capabilities in RF-opaque environments, such as a jungle, that preclude the use of Global Positioning System (GPS) and/or laser ranging systems, utilizing transponders and Global Positioning System (GPS) receivers located on aerial vehicles. The aerial vehicles operate above the RF-opaque environment, and communicate with a ranging device within the RF-opaque environment on frequencies that propagate in the RF-opaque environment. The ranging device transmits RF signals to the transponders, which are received by the transponders and re-broadcasted back to the ranging device on a different frequency. The aerial vehicles also provide their coordinates to the ranging device using their GPS receivers. The ranging device uses information about the transmitted and received RF signals and the GPS coordinates of the aerial vehicles to calculate a perpendicular distance to a property line from the ranging device, and/or to calculate a coordinate location of the ranging device.

The present disclosure relates generally to satellite communication systems, and, more particularly, to trilateration-based satellite location accuracy for improved satellite-based geolocation are provided. In one embodiment, a method comprises: determining, by a processing device, a location of each of a plurality of reference antennas with known locations; obtaining a plurality of distances between a communication satellite and the plurality of reference antennas, each distance of the plurality of distances corresponding to a respective reference antenna of the plurality of reference antennas, at least one distance of the plurality of distances based on an echo message communicated between a particular reference antenna of the plurality of reference antennas and the communication satellite; determining an accurate location of the communication satellite based on trilateration of the plurality of distances from the known locations of the plurality of reference antennas; and utilizing the accurate location of the communication satellite.

According to one or more embodiments herein, interferometry-based satellite location accuracy is provided. In one embodiment, a method comprises: determining, generally at a substantially given time, a reference satellite having a known accurate location within angular proximity of a communication satellite having a known general location; determining an accurate angular position of the communication satellite with relation to the reference satellite from the perspective of at least one ground station antenna of a known accurate location; determining an additional location reference measurement of the communication satellite; determining an accurate location of the communication satellite at the substantially given time based at least in part on the accurate angular position of the communication satellite with relation to the reference satellite from the perspective of the at least one ground station antenna and the additional location reference measurement of the communication satellite; and utilizing the accurate location of the communication satellite.