The present disclosure provides a compliance test method and system for Receiver Autonomous Integrity Monitoring (RAIM) performance of a BeiDou navigation satellite system (BDS) airborne equipment. The method includes: acquiring BDS almanac parameters and test parameters (101); determining whether the satellites are visible according to the almanac parameters and the test parameters (102); acquiring space-time points when the satellites are visible (103); computing the Horizontal Protection Limit (HPL) of each of the space-time points (104); selecting marginal geometries space-time points according to the HPL (105); test the space-time points and the marginal geometries space-time points to obtain a first test result (106); acquiring the configuration parameters and the BDS almanac of the satellite navigation vector signal generator for the marginal geometries space-time points (107); decoding the configuration parameters and the BDS almanac to obtain the number of visible satellites (108); determining whether the number of visible satellites is greater than a threshold (109); testing the marginal geometries space-time points to obtain the second test result if yes (110); and determining whether the first test result is matched with the second test result (111). The method can check whether the BDS airborne equipment meets airworthiness requirements.

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.

Disclosed are techniques for positioning. A receiver measures a time of arrival (ToA) of a positioning reference signal (PRS) transmission of a first PRS sequence transmitted by a first transmitter, measures a ToA of a PRS transmission of a second PRS sequence transmitted by a second transmitter, and determines an observed time difference of arrival (OTDOA) as a difference between the ToA of the PRS transmission of the first PRS sequence and the ToA of the PRS transmission of the second PRS sequence, wherein the OTDOA is less than half a maximum differential delay expected between the PRS transmission of the first PRS sequence and the PRS transmission of the second PRS sequence, and wherein a repetition duration of the first PRS sequence and the second PRS sequence is greater than 10 milliseconds (ms) and at least twice the maximum differential delay.

A method and system for operating an ad hoc communication network under suboptimal commercial global navigation satellite system (GNSS) conditions and a loss of a base station communication link is disclosed. The method includes configuring the ad hoc communication network to operation in in-band or out-of-band mode, allowing device-to-device D2D communication. The method further includes configuring the ad hoc communication system to operate in overlay mode, sharing communication resources between network-controlled resources and D2D resources. The method further includes configuring the D2D resources with a base station precedent to the loss of the base station communication link and enabling the ad hoc communication network to operate in frequency hopping mode. The method further includes disabling physical sidelink control channel synchronization and/or resource management within the ad hoc communication network. In some embodiments of the method, and configuring the ad hoc communication network to include at least one nonstandard-GNSS time-synchronization method.

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.

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 method, apparatus and computer program product are provided to correct a predicted value of the position of a navigation satellite and/or a clock offset of a clock of the navigation satellite. In the context of a method implemented by a client computing device, a prediction is received, from a serving computing device, that includes at least one predicted value for the position of the navigation satellite at one or more points in time within a prediction interval. The method also determines, with the client computing device, such as an Internet of Things device, at least one error component and, based thereupon, corrects the prediction received from the serving computing device by correction at least one predicted value for one or more of: (i) the position of the navigation satellite or (ii) the clock offset for the clock of the navigation satellite.

A target tracking device to estimate a position of a target with high accuracy will be provided. The target tracking device is provided with a communication device and a processor. The communication device performs communication with a plurality of observation satellites that observe the target. The processor executes a selection of satellites, a setting of a schedule and an estimation. The selection of satellites includes selecting two or more selected satellites that observes the target among the plurality of observation satellites. The setting of the schedule includes determining an observation schedule for each of the two or more selected satellite to observe the target and transmitting an observation request signal that represents the determined observation schedule to a corresponding selected satellite. The estimation includes estimating the position of the target based on two or more pieces of high-precision observation information respectively observed by the two or more selected satellites.

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.

A positioning system including a satellite signal receiver 20 that receives satellite signals from a plurality of positioning satellites; a plurality of indoor pseudo satellite stations that transmit pseudo satellite signals; and a pseudo station control device that selects the positioning satellites to be allocated to the plurality of pseudo satellite stations based on the received satellite signals, allocates a PRN code corresponding to each of the selected positioning satellites to each of the plurality of pseudo satellite stations one by one, determines a delay time of the PRN code allocated to the plurality of pseudo satellite stations, and transmits a plurality of pseudo satellite signals generated using the PRN code corresponding to each of the plurality of pseudo satellite stations and the delay time to each of the plurality of pseudo satellite stations.