System and method for temperature-calibration of a crystal oscillator (XO) in a mobile device. A temperature-calibration status of the XO is determined and a trigger condition related to temperature-calibration of the XO is detected. If the temperature-calibration status of the XO is not fully temperature-calibrated or if the XO has not been previously temperature-calibrated, a temperature-calibration session is initiated by an XO manager based on the condition, wherein a receiver is configured to receive signals and temperature-calibration of the XO is performed in a background mode based on the received signals. The condition based triggering ensures that the XO is temperature-calibrated prior to launch of any position based or global navigation satellite systems (GNSS) based applications on the mobile device. The trigger condition can include first use or power-on, charging, presence in an outdoor environment, variation in operating temperature, pre-specified time, and/or user input pertaining to the mobile device.

A GNSS data collection system includes a pole mounted GNSS receiver and inclination sensors. A data collection module provides a data collection graphical user interface (GUI) visible on a hand-held data collector computer. The data collector computer is communicably coupled to the GNSS receiver and receives three-dimensional location data and inclination data for the range pole in real-time. A virtual level component uses the inclination data to display on the GUI real-time tilt information in the form of a virtual bubble level indicator. The inclination data and height of the range pole are used to calculate and display horizontal distance and direction to level the GNSS receiver, using: incline=sqrt(xtilt*xtilt+ytilt*ytilt) where, xtilt=the inclination data for the range pole along the x axis, ytilt=the inclination data for the range pole along the y axis, and horizontaldistancefromlevel=rh*sin(incline) where, rh=the height of the range pole.

A method is provided for calibrating a vehicle-mounted GNSS antenna. The method comprises measuring a response of the antenna, while the antenna is mounted on the vehicle. Based on the measured response, data characterizing a group delay variation of the antenna is calculated. The data may be used to correct ranging measurements derived from GNSS signals received via the vehicle-mounted antenna. Alternatively or in addition, the data may be used in estimating the integrity of a position fix.

A Global Navigation Satellite System (GNSS) receiver that includes a satellite signal generator generating signal data for a signal that is not being tracked by the receiver. The receiver includes a satellite signal generator running an algorithm to process first and second received signals to produce a software-synthesized satellite signal, and the generated signal data is used to correct bias or is communicated to a spaced-apart GNSS receiver or used for onboard positioning calculations. The satellite constellation may be the Galileo constellation, with the first and second signals being E5A and E5B signals tracked by the receiver and the generated third signal being an E5AltBOC signal. With a half-a-cycle bias resolution technique, the satellite signal generator generates synthetic E5AltBOC data of high quality. For a receiver, which physically tracks E5AltBOC, synthetic E5AltBOC may be used to monitor polarity of a physically tracked E5AltBOC and correct it if error is detected.

An apparatus and method of intersensor calibration including using a zero airmass response constant proportional to sensor absolute radiometric gain coefficients to monitor sensor radiometric stability. Tracking the ratio of zero airmass response constant values for similar bands between two sensors provides a parameter on a common radiometric scale for evaluating interoperability performance. The method includes imaging a solar signal using a mirror to create an image reference target, detecting the image reference target using a first sensor, generating a zero airmass response constant based on a ground sampling distance of the first sensor and an at-sensor radiance value, computing a radiometric gain coefficient of the first sensor using the zero airmass response constant, and comparing the radiometric gain coefficient of the first sensor to a radiometric gain coefficient of a second sensor to determine a gain ratio between the first sensor and second sensor.

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 satellite radio wave sensitivity distribution management system for a work vehicle that travels automatically in a work site by satellite navigation technology includes a satellite positioning module that outputs satellite position data and reception sensitivity based on satellite information from a satellite, a sensitivity reduction event detection section that detects occurrence of a sensitivity reduction event, a sensitivity reduction event information generation section that generates sensitivity reduction event information including an occurrence location of the sensitivity reduction event, an occurrence time of the sensitivity reduction event, and satellite identification data, a sensitivity reduction event information storage section, a reception obstacle determination section that determines a reception obstacle as the cause of the sensitivity reduction event, and a sensitivity reduction management section that manages a sensitivity reduction area and a sensitivity reduction time zone.

A method is provided for calibrating a test platform including a plurality of system outputs to align RF signals generated by the system outputs. RF power of a combined RF signal is detected, where the combined RF signal is from a reference RF signal generated by a reference system output in the plurality of system outputs and a test RF signal generated by a test system output in the plurality of systems outputs. A phase of the test RF signal is iteratively shifted relative to the reference RF signal until the detected RF power reaches a minimum. The test RF signal is inverted to be in-phase with the reference RF signal when the combined RF power reaches the minimum. A system is also provided for calibrating a test platform including a plurality of system outputs to align RF signals generated by the system outputs.

Disclosed is a system for providing multiple location corrections streams to receiving devices using a high-power transmitter, such as a television station, for correcting errors in the determination of a location of a receiving device based on satellite data. The system enables a receiving device to select one of the location corrections streams for processing without any upstream/return path link to the television station or processing server. The system includes multiple base stations distributed across a geographic area that each transmit location corrections stream to the processing server, which combines them to a composite corrections stream and transmits it to television stations for further broadcasting. A receiving device within a coverage area of a television station receives the composite corrections stream, selects a corrections stream corresponding to a base station closest to the receiving device, and uses the selected corrections stream to correct the location determined using satellite data.

Methods and apparatus for sensor calibration of a system having an aperture, primary mirror, secondary mirror, and a sensor, such as an FPA IR sensor. A calibration system includes calibration energy sources with a movable first mirror configured to be selectively inserted into the optical path and select one of the calibration energy sources and a second mirror configured to image the selected calibration energy source.