Abstract: A method of communicating satellite tracking information among a network of global navigation satellite system receivers is described. The method includes determining at a first GNSS receiver which satellites in a constellation of satellites have been continuously tracked over a preceding selected time period, and for each such satellite determining its elevation with respect to the zenith. Only the elevation value for the lowest satellite in the set of satellites for which all satellites of higher elevation values have been continuously tracked over the selected time period is then transmitted to the second GNSS receiver. That receiver can then reconstruct the set of satellites which have been continuously tracked.

Abstract: A surveying apparatus includes an antenna to receive a positioning signal. The surveying apparatus further includes a tilt sensor to obtain a tilt measurement that indicates a degree of tilt of the survey apparatus. The surveying apparatus further includes a processor to obtain a positioning measurement from the positioning signal, and to determine a degree of accuracy of the positioning measurement based on the tilt measurement.

Abstract: A method of communicating corrections for information related to satellite signals among global navigation satellite system (GNSS) receivers is described. An ionosphere correction for ionosphere signal path delay is determined for a first satellite. This ionosphere correction is then compared to an ionosphere correction for ionosphere signal path delay for a satellite assumed to be directly over the receiver. The receiver then sends a message which includes only the difference between the ionosphere correction for the actual observation and the ionosphere correction for a satellite assumed to be at the zenith.

Abstract: A format for providing messages among GNSS apparatus includes providing a message identification block and a message body. The message identification block includes information specifying a message length and a message type block specifying a message type. Rather than sending all data from one apparatus to another, ambiguous observation data is sent to conserve bandwidth. At the sender a deconstruction of GNSS code and carrier observations using knowledge of the signal structure and constellation geometry, together with simplifications of atmospheric models, allows removal from the observation data of that information which can be implicitly understood or recreated by the recipient. This enables only the necessary information to be packed for transmission to the recipient.

Abstract: A format for providing messages among GNSS apparatus includes providing a message identification block and a message body. The message identification block includes information specifying a message length and a message type block specifying a message type. Rather than sending all data from one apparatus to another, ambiguous observation data is sent to conserve bandwidth. At the sender a deconstruction of GNSS code and carrier observations using knowledge of the signal structure and constellation geometry, together with simplifications of atmospheric models, allows removal from the observation data of that information which can be implicitly understood or recreated by the recipient. This enables only the necessary information to be packed for transmission to the recipient.

Abstract: A method of communicating corrections for information related to satellite signals among global navigation satellite system (GNSS) receivers is described. An ionosphere correction for ionosphere signal path delay is determined for a first satellite. This ionosphere correction is then compared to an ionosphere correction for ionosphere signal path delay for a satellite assumed to be directly over the receiver. The receiver then sends a message which includes only the difference between the ionosphere correction for the actual observation and the ionosphere correction for a satellite assumed to be at the zenith.

Abstract: A method of communicating satellite tracking information among a network of global navigation satellite system receivers is described. The method includes determining at a first GNSS receiver which satellites in a constellation of satellites have been continuously tracked over a preceding selected time period, and for each such satellite determining its elevation with respect to the zenith. Only the elevation value for the lowest satellite in the set of satellites for which all satellites of higher elevation values have been continuously tracked over the selected time period is then transmitted to the second GNSS receiver. That receiver can then reconstruct the set of satellites which have been continuously tracked.

Abstract: A surveying apparatus includes an antenna to receive a positioning signal. The surveying apparatus further includes a tilt sensor to obtain a tilt measurement that indicates a degree of tilt of the survey apparatus. The surveying apparatus further includes a processor to obtain a positioning measurement from the positioning signal, and to determine a degree of accuracy of the positioning measurement based on the tilt measurement.

Abstract: In accordance with embodiments of the invention, a skyward-looking sensor enables classification of points in its hemispherical field of view as either sky, partial sky or not sky, which in turn enables determination from data supplied by the GNSS receiver of whether each satellite in the GNSS antenna's field of view is in a region of sky, partial sky or not sky. Pseudrange and phase data from GNSS satellites determined to be in a region of sky can be considered reliable and used with confidence in a positioning solution. Pseudrange and phase data from GNSS satellites determined to be in a region of partial sky can be considered suspect and can therefore only contribute to a position solution with limited confidence and decreased accuracy. Pseudorange and phase data from GNSS satellites determined to be in a region of no sky can be considered unreliable and excluded from use in a positioning solution.

Abstract: A method and system for variable data rate transmission in a real-time kinematic (RTK) positioning system. An RTK positioning system having a reference station and a rover utilizes wireless communications for data transfer. The data transmission rate between the reference station and the rover is dynamically controlled by a programmable transmission controller. The transmission rate is determined on the basis of specific parameters. Parameters that may be used to determine the data transmission rate include rover demand, required rover accuracy, satellite positioning system (SATPS) events, the required data for ambiguities, and the type and content of the data transmitted.

Abstract: In accordance with embodiments of the invention, a skyward-looking sensor enables classification of points in its hemispherical field of view as either sky, partial sky or not sky, which in turn enables determination from data supplied by the GNSS receiver of whether each satellite in the GNSS antenna's field of view is in a region of sky, partial sky or not sky. Pseudrange and phase data from GNSS satellites determined to be in a region of sky can be considered reliable and used with confidence in a positioning solution. Pseudrange and phase data from GNSS satellites determined to be in a region of partial sky can be considered suspect and can therefore only contribute to a position solution with limited confidence and decreased accuracy. Pseudorange and phase data from GNSS satellites determined to be in a region of no sky can be considered unreliable and excluded from use in a positioning solution.

Abstract: A method and system for variable data rate transmission in a real-time kinematic (RTK) positioning system. An RTK positioning system having a reference station and a rover utilizes wireless communications for data transfer. The data transmission rate between the reference station and the rover is dynamically controlled by a programmable transmission controller. The transmission rate is determined on the basis of specific parameters. Parameters that may be used to determine the data transmission rate include rover demand, required rover accuracy, satellite positioning system (SATPS) events, the required data for ambiguities, and the type and content of the data transmitted.

Abstract: A method and system for variable data rate transmission in a real-time kinematic (RTK) positioning system. An RTK positioning system having a reference station and a rover utilizes wireless communications for data transfer. the data transmission rate between the reference station and the rover is dynamically controlled by a programmable transmission controller. The transmission rate is determined on the basis of specific parameters. Parameters that may be used to determine the data transmission rate include rover demand, required rover accuracy, satellite positioning system (SATPS) events, the required data for ambiguities, and the type and content of the data transmitted.

Abstract: The system and method for long baseline RTK survey are disclosed. The system includes a primary base station (PBS), a secondary base station (SBS), a primary data link between the PBS and the SBS, and a secondary data link between the SBS and a rover. The PBS, the SBS, and the rover are equipped with satellite antennas for satellite navigational purposes, and with the wireless Internet data accesses devices (WIDAD). The long baseline vector between the PBS and the rover is established by combining the primary baseline vector between the SBS and the PBS and the secondary baseline vector between the SBS and the rover. The PBS is placed in a position with a known location. The PBS wirelessly downloads its logged set of data into the Internet server using the (PBS-WIDAD). The SBS determines its precise position coordinates by accessing wirelessly the PBS logged data on the Internet server using the (SBS-WIDAD).

Abstract: The system and method for long baseline RTK survey are disclosed. The system includes a primary base station (PBS), a secondary base station (SBS), a primary data link between the PBS and the SBS, and a secondary data link between the SBS and a rover. The PBS, the SBS, and the rover are equipped with satellite antennas for satellite navigational purposes. The long baseline vector between the PBS and the rover is established by combining the primary baseline vector between the SBS and the PBS and the secondary baseline vector between the SBS and the rover. The PBS is placed in a position with a known location. The final SBS position is accurately determined using the PBS position during two initialization steps.

Abstract: A first position determining device at a known position transmits a data signal identifying the known position. A second position determining device is responsive to the data signal and movable to a position near but displaced from a survey point. The position of the second position determining device is determined relative to the known position, and the range and bearing of the survey point is determined relative to the second position determining device.

Abstract: A method and a system for remote control of a rover over a long base line is disclosed. The system includes a primary base station (PBS), a secondary base station (SBS), a rover, a primary long line data link between PBS and SBS, and a secondary two-way data link between the SBS and the rover. The primary data link and the secondary data link comprise a long baseline feedback loop that is used to transmit the control data to the rover, to adjust the control data, and to transmit back from the rover to the SBS and to the PBS the collected feedback data.

Abstract: An apparatus and a method of purchasing or leasing the time dependent option of operation of an instrument are disclosed. An apparatus generates and uses a time dependent password configured to be matched with at least one time dependent parameter in order to activate the instrument. The apparatus includes a time-antispoof device in order to prevent spoofing the purchased time of operation of the instrument. The time-antispoof device includes a satellite navigation receiver in order to enforce the antispoof option.

Abstract: A method and apparatus for automatic event detection and processing is provided. A positioning system receiver includes a position measurement device and a logging device. The position measurement device is configured to receive and process signals from a positioning system. The logging device is coupled to the position measurement device for recording data received from the position measurement device. The logging device records the data at a current logging rate. The positioning system receiver detects an event via an external sensor or with reference to satellite data, for example. In response to the event, the logging device automatically modifies data logging processing such as the current logging rate. Additionally, to allow a post processing system to go backwards in time relative to the event, the current logging rate may be increased for a predetermined amount of time preceding the occurrence of the event.

Abstract: A system embodiment of the present invention comprises a fixed and a roving pair of four-observable GPS receivers and a communication link between them for double differencing code and carrier measurements. Carrier phase integer ambiguities are resolved efficiently by searching the simultaneous narrow-lane intersections of both the L1 and L2 wave fronts propagated by the GPS satellites being tracked. External constraint information, such as elevation, is additionally used to speed up integer ambiguity resolution. Data between the reference station and the rover is communicated in compressed form at a regular interval, e.g., once a second at each epoch, and demi-measurements of carrier phase are obtained more frequently, e.g., ten times a second, and used to propagate solutions between epochs.