An electronic watch includes a GPS receiver, a first time correction unit configured to correct time using the time information received by the GPS receiver, a beacon receiver configured to receive a beacon signal containing beacon identification information transmitted from a beacon installed indoors, a first storage unit configured to store beacon identification information and time difference information corresponding to the beacon identification information, a second time correction unit configured to correct a time difference using the beacon signal received by the beacon receiver and the time difference information stored in the first storage unit, and a button configured to accept a reception instruction of the beacon signal, which is operated by an operator. The beacon receiver is configured to receive a beacon signal when the button accepts the reception instruction.

An electronic watch includes a GPS receiver, a first time correction unit configured to correct time using the time information received by the GPS receiver, a beacon receiver configured to receive a beacon signal containing beacon identification information transmitted from a beacon installed indoors, a first storage unit configured to store beacon identification information and time difference information corresponding to the beacon identification information, a second time correction unit configured to correct a time difference using the beacon signal received by the beacon receiver and the time difference information stored in the first storage unit, and a button configured to accept a reception instruction of the beacon signal, which is operated by an operator. The beacon receiver is configured to receive a beacon signal when the button accepts the reception instruction.

A method for image-based point measurement includes moving a surveying system along a path through a surrounding and capturing a series of images of the surrounding. A subset of images are defined as frames and a subset of frames are defined as key-frames. Textures are identified in first and second frames and are tracked in successive frames to generate first and second frame feature lists. A structure from motion algorithm is used to calculate camera poses for the images based on the first and second frame feature lists. Corresponding image points in images of the series of images are identified using feature recognition in at least a plurality of images. Three-dimensional coordinates of the selected image point are determined using forward intersection with the poses of the subset of images in which corresponding image points are identified. The three-dimensional coordinates of the selected image point are presented to the user.

A surveying system for a construction site has a restricted antenna system with a plurality of fixed location antennas each defined by a set of location data associated with a specific deployment position. The surveying system also has a computing device with a data processor and a display screen. A communications module establishes a data transfer link with the restricted antenna system over which spatial data for distances between current positions of the computing device and one or more of the plurality of fixed location antennas are received. The computing device is loadable with project drawings corresponding to the construction site and displayable on the display screen. A position marker is overlaid on the display of the project drawing at a position thereon corresponding to a computing device location value derived from the spatial data and the location data of one or more of the fixed location antennas.

A surveying system for a construction site has a restricted antenna system with a plurality of fixed location antennas each defined by a set of location data associated with a specific deployment position. The surveying system also has a computing device with a data processor and a display screen. A communications module establishes a data transfer link with the restricted antenna system over which spatial data for distances between current positions of the computing device and one or more of the plurality of fixed location antennas are received. The computing device is loadable with project drawings corresponding to the construction site and displayable on the display screen. A position marker is overlaid on the display of the project drawing at a position thereon corresponding to a computing device location value derived from the spatial data and the location data of one or more of the fixed location antennas.

A method including operating a vehicle in a medium. The vehicle is subject to advection due to movement of the medium. The method also includes measuring, using a navigation system, positions of a vehicle over time. The method also includes measuring, using a directional sensor, a course-through-medium over the time. The method also includes calculating, using the positions and the course-through-medium, a variation of a speed-over-ground of the vehicle over the time as a function of the course-through-medium over the time. The method also includes concurrently estimating, using the variation, 1) an average speed-through-medium for the vehicle over the time, and 2) an advection rate of the medium, and 3) an advection direction of the medium.

The present invention discloses a high-precision point positioning method and device based on a smartphone. The method of the present invention, which belongs to the technical field of satellite positioning, improves the conventional PPP uncombined positioning model, and only uses original GNSS observation values received by a smartphone to carry out high-precision positioning without GNSS reference stations. The positioning method of the present invention comprises following steps: acquiring original observation values of the smartphone, such as GNSS pseudoranges and carrier phases; after preprocessing the data to decrease part of error influences, generating an uncombined model from the original observation values according to an improved precise point positioning method based on an estimation of double clock biases; determining each satellite observation value weight according to a satellite elevation angle; and carrying out filtering positioning by an improved Kalman filtering method to give a high-precision point positioning result.

A method for detecting time rollovers is disclosed. The method may include receiving time data including week data and second data and processing the time data to generate a first date. The method may include generating, based on the first date and an offset value, a second date and obtaining, when the second date is prior to a baseline date, a network date. The method may include assigning the network date as the baseline date and processing the network date and the first date to determine an updated offset value. The method may include storing the updated offset value as the offset value and determining, based on the network date, a system date.

A method for detecting time rollovers is disclosed. The method may include receiving time data including week data and second data and processing the time data to generate a first date. The method may include generating, based on the first date and an offset value, a second date and obtaining, when the second date is prior to a baseline date, a network date. The method may include assigning the network date as the baseline date and processing the network date and the first date to determine an updated offset value. The method may include storing the updated offset value as the offset value and determining, based on the network date, a system date.

Location polygons are defined along traffic lanes and parking spaces to facilitate determination of the location of a vehicle relative to features associated with the location polygons. The location polygons are used, in one application, to identity entrance and exit of a special toll lane along a roadway, and to ensure that the vehicle properly enters and exits the tolling lane.