The invention relates to a method for calibrating a receiver comprising a plurality of analog reception channels each including an antenna element of a multi-element antenna, the plurality of analog reception channels comprising a reference channel, the method comprising determining (E1-E4) and correcting (E5), for each analog reception channel other than the reference channel, a phase shift with the reference channel, said determination comprising: calculating (E1) an observed covariance matrix (R.sub.ZZ.sup.t,e) representative of the covariance between samples (Z.sub.t.sup.e), collected in parallel on each of the analog reception channels over a period of time, of one or more incident reference radio signals on the multi-element antenna, obtaining (E2) an estimate () of a reference covariance matrix representative of the covariance between samples of said incident radio signal(s) which would be collected in parallel on each of the analog reception channels over the period of time in the absence of phase shift between the analog reception channels, calculating (E3) a product matrix (), resulting from the term-by-term matrix product of the observed covariance matrix with the estimate of the reference covariance matrix; determining (E4) the argument () of complex terms of the product matrix.

The present teaching relates to apparatus, method, medium, and implementations for initiating sensor calibration. A first GPS signal is received by a GPS receiver residing in an ego vehicle and is used to determine a first geo-position of the ego vehicle. A GPS related signal transmitted by a fiducial marker is received and is used to obtain a second geo-position of the fiducial marker. A distance between the ego vehicle and the fiducial marker is determined based on the first and second geo-positions and is used to determine whether to initiate calibration of one or more sensors using the fiducial marker.

A test device determines a Global Navigation Satellite System (GNSS) signal propagation delay in a GNSS signal distribution system (GSDS) for a radio access network, and can further perform long-term tests on a GSDS without having access to a GNSS satellite. The test device includes a GNSS receiver and a clock that can be re-tuned to accommodate performing tests on the GSDS.

A system for managing a time reference includes a real-time clock, an interface, and a processor. The real-time clock store an RTC time. The interface is configured to receive a GPS time and a cellular time. The processor is configured to: indicate to start a time-speed adjustment loop; determine a true time based at least in part on the GPS time and the cellular time; determine an error between the true time and the RTC time; determine an RTC speed calibration adjustment based at least in part on the error; and adjust the real-time clock speed based at least in part on the RTC speed calibration adjustment.

A method, apparatus, and system are disclosed for providing modified orbital assistance data to a mobile station to determine its location using global navigation satellite system (GNSS). The modified orbital assistance data may include predicted orbital information for the GNSS satellites combined with antenna phase center offset data for one or more GNSS satellites. The antenna phase center offset data may indicate an offset distance from the center of mass of the GNSS satellite to a position on an antenna of the respective GNSS satellite. The modified orbital assistance data may be in an earth-centered earth-fixed (ECEF) frame of reference and the antenna phase center offset data may be in a body-centered frame of reference.

Methods and apparatus to monitor GPS/GNSS atomic clocks are disclosed. An example method includes establishing a measured difference between an atomic frequency standard (AFS) and a monitoring device. The method also includes modeling an estimated difference model between the AFS and the monitoring device, and computing a residual signal based on the measured difference and the estimated difference model. In addition, the method includes analyzing, by a first detector, the residual signal at multiple thresholds, each of the thresholds having a corresponding persistency defining the number of times a threshold is exceeded before one or more of a phase jump, a rate jump, or an acceleration error is indicated. Furthermore, the method includes analyzing, by a second detector, a parameter of the estimated difference model at multiple thresholds, each of the thresholds having a corresponding persistency defining the number of times a drift threshold is exceeded before a drift is indicated.

A positioning system having an onboard positioning device and a roadside device is provided. The onboard positioning device receives a plurality of first positioning signals and records a positioning moving locus of a vehicle according to the first positioning signals. The roadside device detects a real moving locus of the vehicle. The onboard positioning device obtains the real moving locus from the roadside device, and calculates a positioning calibration value according to coordinates of the positioning moving locus and coordinates of the real moving locus. Furthermore, the onboard positioning device receives a plurality of second positioning signals and calculates and outputs a plurality of calibrated positioning coordinates according to the second positioning signals and the positioning calibration value.

Techniques described herein leverage multi-constellation, multi-frequency (MCMF) functionality to provide a local Real-Time Kinematic (RTK) solution for a mobile device in which an initial highly-accurate location determination for the mobile device can be leveraged to generate RTK correction information that can be used to make subsequent, highly-accurate location determinations without the need for measurement information from an RTK base station. This RTK correction information can be applied to Global Navigation Satellite System (GNSS) measurements taken by the mobile device over a long period of time while retaining the ability to produce highly-accurate location determinations for the mobile device. And additional correction information may be obtained and applied to the RTK correction information to extend this period of time even longer.

A method for compensating group delay variations in a CDMA spread spectrum receiver, comprising: receiving an RF signal; generating an ideal replica signal; filtering the RF signal by one or more filters; obtaining an ideal auto-correlation function (ACF) of the ideal replica signal; distorting the ideal ACF to generate a distorted ACF by a filtering model of the one or more filters; aligning the ideal ACF and the distorted ACF; calculating a set of correction factors based on a ratio of the ideal ACF and the distorted ACF; calculating a cross-correlation signal based on the filtered RF signal and the ideal replica signal; and obtaining a compensated correlation signal by applying the set of correction factors to the cross-correlation signal.

Techniques described herein leverage MCMF functionality to provide a local RTK solution for a mobile device in which an initial highly-accurate location determination for the mobile device can be leveraged to generate RTK correction information that can be used to make subsequent, highly-accurate location determinations without the need for measurement information from an RTK base station. This RTK correction information can be applied to GNSS measurements taken by the mobile device over a long period of time while retaining the ability to produce highly-accurate location determinations for the mobile device. And additional correction information may be obtained and applied to the RTK correction information to extend this period of time even longer.