Abstract: A system and method for compensating for changes in relative antenna attitude in a single-receiver position detection system, such as a differential carrier phase GPS system, utilizes sensor input to detect changes in the relative attitude of at least two antennas or an antenna positioner, such as an motorized actuator or operator, that orients or re-orients the antennas to a predetermined orientation. The changes in the detected relative carrier phase due to the right hand circular polarized nature of the carrier signals are thus corrected. In this way, the high positional accuracy associated with kinematic GPS systems, for example, can be achieved even when the system's antennas are not constrained by a common rigid body, for example.

Abstract: A system including a mobile vehicle, an implement, a position sensor, a controller, a user interface (a touch-screen monitor, video monitor or keypad, as examples), a software program to compute a calibration trajectory, and a steering system for steering the vehicle to the desired or adjusted trajectory based on the error between the vehicle's desired and actual positions. In one embodiment, non-co-located sensing and control combine with a calibration procedure to help eliminate model error. Another embodiment uses co-located sensing (but not control) to calibrate the model.

Abstract: A measurement system and an associated method for determining the positions of multiple antennas to centimeter level accuracy. The system involves minimal incremental hardware cost per additional antenna to be tracked. The primary frequency RF signals are processed by a primary frequency RF section dedicated to each antenna. The secondary frequency RF signals from all the antennas are multiplexed and input to a secondary frequency RF section corresponding to each secondary RF frequency. A correlator derives code and carrier phase for the processed primary and secondary frequency RF signals. A processor thereafter reconstructs the carrier phase for the secondary frequency RF signals. The processor finally uses these reconstructed phases to resolve carrier cycle ambiguities and to determine the position of the antennas.

Abstract: A method and a system for L1/L2 phase and magnitude determination in satellite navigation equipment is disclosed herein. The method generates separate W code estimates for the L1 signal and the L2 signal, the estimates being uncorrelated with the error in the inphase and the quadrature components of the corresponding signals. The W code is estimated using both the L1 signal as well as the L2 signal. The L1 and L2 baseband signals are obtained from the corresponding RF signals. The baseband signals are added and then filtered using a non-causal FIR LPF. This filter has the property that the output at a time instant is uncorrelated with the input at that time instant. In the preferred embodiment, a one-W-code-bit I&D filter is used instead of a FIR LPF. In an alternate embodiment, a single W code estimate is obtained for both the L1 and the L2 signal.

Abstract: A method for adjusting a desired trajectory of an automatically guided vehicle guidance system to match a physical constraint such as an obstacle or boundary. The method works around obstacles and boundaries as they occur, consistent with the original trajectory. The method is independent of the type of vehicle. The method may be used regardless of whether the vehicle is under automatic guidance, and the method has a low computational cost.

Abstract: A low-cost, solid-state position sensor system suitable for making precise code and carrier phase measurements in the L1 and L2 bands of GPS uses an ordinary, low-cost OEM card single-frequency carrier phase tracking C/A code receiver and includes low-cost hardware for sensing the L1 and L2 components of GPS carrier phase. Such measurements are suitable for general use in a variety of fields, including surveying. They are also of sufficient quality to be used in controlling heavy machinery, such as aircraft, farm tractors, and construction and mining equipment. A C/A code continuous tracking GPS receiver is used to produce GPS positioning fixes and real-time L1 carrier phase measurements. This C/A code receiver generates timing and reference information for a digital sampling component. This sampling component processes the L1 and L2 signals from the GPS signals in view.

Abstract: A low-cost, solid-state position sensor system suitable for making precise code and carrier phase measurements in the L1 and L2 bands of GPS uses an ordinary, low-cost OEM card single-frequency carrier phase tracking C/A code receiver and includes low-cost hardware for sensing the L1 and L2 components of GPS carrier phase. Such measurements are suitable for general use in a variety of fields, including surveying. They are also of sufficient quality to be used in controlling heavy machinery, such as aircraft, farm tractors, and construction and mining equipment. A C/A code continuous tracking GPS receiver is used to produce GPS positioning fixes and real-time L1 carrier phase measurements. This C/A code receiver generates timing and reference information for a digital sampling component. This sampling component processes the L1 and L2 signals from the GPS signals in view.

Abstract: A GPS system and method for generating precise position determinations. The GPS system includes a ground based GPS reference system which receives with a reference receiver GPS signals and makes phase measurements for the carrier components of the GPS signals. The GPS reference system then generates and broadcasts an initialization signal having a carrier component and a data link signal having a data component. The data component of the data link signal contains data representing the phase measurements made by the reference receiver. The GPS system also includes a GPS mobile system which receives with a mobile position receiver the same GPS signals as were received by the reference system. In addition, the GPS position receiver receives the data link and initialization signals broadcast by the reference system.

Abstract: A GPS system and method for generating precise position determinations. The GPS system includes a ground based GPS reference system which receives with a reference receiver GPS signals and makes phase measurements for the carrier components of the GPS signals. The GPS reference system then generates and broadcasts an initialization signal having a carrier component and a data link signal having a data component. The data component of the data link signal contains data representing the phase measurements made by the reference receiver. The GPS system also includes a GPS mobile system which receives with a mobile position receiver the same GPS signals as were received by the reference system. In addition, the GPS position receiver receives the data link and initialization signals broadcast by the reference system.