An apparatus and a method for providing a global localization output are provided. When the apparatus receives navigation signals, the apparatus processes the signals to determine, based on a fixed earth-centered, earth-fixed (ECEF) reference pose of a reference point in an ECEF coordinate, a new ECEF pose, and to convert the fixed ECEF reference pose to an east-north-up (ENU) reference pose in an ENU coordinate. When the apparatus determines that a jump occurs in the new ECEF pose based on a pose change between the new ECEF pose and a previous ECEF pose, the apparatus calculates a reference shift of the ENU reference pose based on the pose change to absorb the jump in the ENU coordinate, and updates the ENU reference pose based on the reference shift. Thus, a new ENU local pose may be obtained using the ENU reference pose.

Various arrangements for compensating for Doppler shift on a non-terrestrial orthogonal frequency division multiplex (OFDM) network are presented. A received frequency of a downlink satellite message received from a satellite may be determined. A downlink frequency delta between an expected frequency of the downlink satellite message and the received frequency of the downlink satellite message can be calculated. An uplink frequency delta based on the calculated downlink frequency delta may be calculated. An uplink transmission frequency at which an uplink OFDM symbol is transmitted may be calculated based on the calculated uplink frequency delta.

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.

A positioning device receives positioning signals from multiple positioning satellites respectively provided by multiple positioning systems, selects one or more use systems to be used in a positioning calculation processing among the multiple positioning systems based on a determination of whether a surrounding environment is an environment in which a multipath is likely to occur, and performs the positioning calculation processing by using the positioning signals from the positioning satellites provided by the positioning systems selected as the use systems.

Apparatus and method for communication in non-terrestrial networks are disclosed. A set of Doppler shift curves for different distances to one or more satellite orbits is obtained. Measurements of satellite transmission are performed to obtain estimate of instantaneous Doppler shift of the transmission, the measurements including a timestamp. A Doppler shift curve corresponding to the measurements is calculated. A time offset on the selected curve is determined utilising the timestamps of the measurements, the time offset indicating the position of the Doppler shift of the apparatus on the curve. The Doppler shift of the satellite transmission is determined utilising the selected curve and the time offset

An assisted satellite positioning system based on detecting signals from a number of satellites includes: (a) a mobile receiver; and (b) a base station communicating with the receiver over a low-power wireless communication network, the base station providing ephemeris data of a selected number of the satellites, but not all, using a compressed data format. The ephemeris data may include data concerning doppler frequency variations or elevation variations of the selected satellites over a predetermined time interval. The doppler frequency variations and the elevation variations may be represented in the compressed format by coefficients of a polynomial function of time. The polynomial function may be weighted to have lesser relative errors in larger doppler frequencies than lesser doppler frequencies, or to have lesser relative errors in lesser elevations than larger elevations. In one implementation, the low-power wireless communication network—such as a LoRa network—that has a range of at least 10 miles.

A system for updating almanac data in low-power GNSS mobile devices (30-34), including a server that keeps a local copy of the almanacs stored in each of the devices and evaluates repeatedly the quality of the almanac of each of the mobile devices (30-34). The evaluation comprises predicting the Doppler shifts for all the satellites potentially receivable by the mobile device using the orbital parameters in the copy and comparing the result with an accurate determination of the same Doppler shifts based on real orbital data.

An electromagnetic transmission carrying a bauded signal, such as a transmission from an orbiting satellite, is processed for Doppler shift analysis. The electromagnetic transmission is captured and a non-linear operation is performed to expose a cyclostationary feature of the captured transmission that defines a rate-line having a rate-line frequency that is related to the bauded signal and to the motion of the transmitter relative to the receiver. The rate-line frequency is tracked in time to generate data indicative of Doppler shift associated with the satellite. The data are then supplied to a tracking receiver.

A tracking loop and associated method for tracking a satellite signal in a GNSS receiver and for determining a line-of-sight (LOS) signal from a plurality of satellite signals received by the GNSS receiver from a satellite. One or more first correlators perform a correlation between a code signal derived from one of the received satellite signals and a plurality of corresponding replica code signals to determine a plurality of code correlation sums comprising a prompt code correlation sum, one or more early code correlation sums and one or more late code correlation sums. One or more second correlators correlate the plurality of code correlation sums with a plurality of replica carrier signals, each having a different Doppler frequency offset, to determine, for each of the plurality of code correlation sums, a set of correlation magnitudes at frequencies of the plurality of replica carrier signals. An LOS identification module identifies the LOS signal based on a signal propagation delay corresponding to one or more local maxima within the sets of correlation magnitudes.

A system and method for determining accurate positions of stationary global navigation satellite system (GNSS) sensors are provided. The method comprises triggering collection of satellite measurements by each of at least a first stationary GNSS sensor and a second stationary GNSS sensor, wherein the satellite measurements are collected per epoch; determining a position of the first stationary GNSS sensor using the satellite measurements collected by the first stationary GNSS; and determining a position of the second stationary GNSS sensor using the satellite measurements collected by the second stationary GNSS and at least the determined position of the first stationary GNSS, wherein the first stationary GNSS sensor is deployed in the vicinity of the second GNSS sensor.