Abstract: A system and method for mitigating a multi-path-induced error in a global navigation satellite system (GNSS) is described. In one embodiment of the method, a composite signal is received. The composite signal includes a band-limited direct-path signal and at least one band-limited multi-path signal that are each modulated with periodic phase reversals. The composite signal is measured as a function of time during a time interval having at least one of the periodic phase reversals. A phase error ?? between the composite signal and the direct-path signal due to the multi-path signal is determined using the measured composite signal as a function of time and a pre-determined filter characteristic corresponding to a filter used to band limit the direct-path signal and the multi-path signal. The phase error ?? in a navigation computation is corrected.

Abstract: A decoherence plate provides reduced field coupling or improved isolation between two or more antennas. An antenna module includes a first antenna, a second antenna and a decoherence plate having a surface. The first antenna transmits one or more electromagnetic signals. The surface of the decoherence plate is positioned in a plane perpendicular to a line connecting the first antenna and the second antenna. For each first path from the first antenna to the plane to the second antenna, in a plurality of paths having a range of path lengths, there is a corresponding second path, from the first antenna to the plane to the second antenna, that is substantially 180° out of phase for a respective wavelength in the one or more electromagnetic signals transmitted by the first antenna. In this way, the decoherence plate reduces the field coupling between the first antenna and the second antenna.

Abstract: The present invention includes a method for a combined use of a local positioning system, a local RTK system and a regional, wide-area, or global differential carrier-phase positioning system (WADGPS) in which disadvantages associated with the local positioning system, the RTK and the WADGPS navigation techniques when used separately are avoided. The method includes determining a first position of the object based on information from the WADGPS, and determining a second position of the object based on position information from a local positioning/RTK positioning system. Thereafter, position determined by the WADGPS and the position determined by the local positioning/RTK positioning system are compared.

Abstract: A local positioning system using co-polarized and cross-polarized radar mapping is provided. In one embodiment of the method, at least a first electromagnetic pulse having a first polarization is transmitted. A first return signal preferentially having the first polarization is received over a respective period of time. The first return signal is processed so as to isolate a first return pulse corresponding to an object within a radar detection area of the positioning system. At least a second electromagnetic pulse having the first polarization is also transmitted. A second return signal preferentially having a second polarization is received over a respective period of time. The second return signal is processed so as to isolate a second return pulse corresponding to the object. A characteristic of the object is determined in accordance with a relative signal strength of the first return pulse and the second return pulse.

Abstract: A positioning system includes a passive, isotropic reflecting landmark at a fixed position and a device. The device transmits an electromagnetic pulse having a circular polarization and receives a return signal over a period of time. The return signal includes a reflected pulse from the reflecting landmark. The processes the return signal to isolate the reflected pulse from the return signal and to determine a range from the device to the reflecting landmark. The reflecting landmark includes a first passive reflector, a second passive reflector, and a static structure configured to statically position the second passive reflector at an angle relative to the first passive reflector. The device optionally moves in a particular direction while receiving the return signal, detects a Doppler shift in the reflected pulse portion of the return signal, and determines an angle between the particular direction and a straight line between the device and the landmark.

Abstract: An antenna includes a first antenna element and a second antenna element. The first antenna element and the second antenna element are configured to transmit and receive signals in a first band of frequencies and in a second band of frequencies. A first pair of delay lines is coupled to the first antenna element and a second pair of delay lines coupled to the second antenna element. A first delay line in the first pair of delay lines and the second pair of delay lines is configured to phase shift electrical signals coupled to the first antenna element and the second antenna element such that a first impedance of the antenna is approximately equal in the first band of frequencies and the second band of frequencies. A second delay line in the first pair of delay lines and the second pair of delay lines is configured to convert the first impedance to a second impedance.

Abstract: A positioning system includes a device, having an antenna and a reflector with a known position proximate to the antenna, that transmits at least an electromagnetic pulse having a carrier signal frequency. The device receives a return signal over a period of time, wherein the return signal includes a return pulse from an object within a radar detection area of the device and at least one multi-path pulse. The device processes the return signal so as to isolate the return pulse and the at least one multi-path pulse from the return signal. The device determines a range from the device to the object and the position of the device relative to the object. The range is determined in accordance with a time of arrival of the return pulse and the position is determined in accordance with a time of arrival of the at least one multi-path pulse.

Abstract: A positioning system includes a plurality of devices configured to exchange RF signals with one another. A first device periodically receives a message from each other device during time slots assigned them. The received message includes information representing a time of arrival at the other device of a respective message transmitted by the first device. A time of arrival of the message from each of the other devices is determined by the first device. The first device periodically transmits messages to the other devices, each transmitted message including information representing the determined time of arrival for at least one of the other devices. A range from the first device to each of a plurality of the other devices is determined as function of the determined time of arrival of the message from the other device and the time of arrival information in the message from the other device.

Abstract: A positioning system includes a passive, isotropic reflecting landmark at a fixed position and a device. The device transmits an electromagnetic pulse having a circular polarization and receives a return signal over a period of time. The return signal includes a reflected pulse from the reflecting landmark. The processes the return signal to isolate the reflected pulse from the return signal and to determine a range from the device to the reflecting landmark. The reflecting landmark includes a first passive reflector, a second passive reflector, and a static structure configured to statically position the second passive reflector at an angle relative to the first passive reflector. The device optionally moves in a particular direction while receiving the return signal, detects a Doppler shift in the reflected pulse portion of the return signal, and determines an angle between the particular direction and a straight line between the device and the landmark.

Abstract: A method and system are provided to determine a relative position vector between primary receiver associated with a reference station and secondary receiver associated with a user. The method and system determine a position of the reference station at the reference station according to signals received thereat from a plurality of satellites, determine a position of the user receiver at the user based on measurements obtained thereat and on error corrections computed at the reference station, and compute the relative position vector by differencing the position of the reference station and the position of the user.

Abstract: The present invention includes a process for navigating an object according to signals from satellites by propagating the position of the object forward in time using successive changes in the carrier-phase measurements. The process computes at a low rate matrices required for solving for the position of the objects, and repeatedly uses the most recently computed matrices to compute position updates at a high rate until the next low-rate computation is completed.

Abstract: The present invention includes a method for a combined use of a local RTK system and a regional, wide-area, or global differential carrier-phase positioning system (WADGPS) in which disadvantages associated with the RTK and the WADGPS navigation techniques when used separately are avoided. The method includes using a known position of a user receiver that has been stationary or using an RTK system to initialize the floating ambiguity values in the WADGPS system when the user receiver is moving. Thereafter, the refraction-corrected carrier-phase measurements obtained at the user GPS receiver are adjusted by including the corresponding initial floating ambiguity values and the floating ambiguity values are treated as well known (small variance) in subsequent processes to position the user receiver in the WADGPS system.

Abstract: A method for generating satellite clock corrections for a WADGPS network computers satellite clock corrections after removing other substantial error components. Errors caused by the ionosphere refraction effects are removed from GPS measurements taken at reference stations using dual-frequency GPS measurements. The multipath noise are removed by smoothing of GPS pseudorange code measurements with carrier-phase measurements. The tropospheric refraction effect can be largely removed by modeling, and if desired, can be improved by the use of small stochastic adjustments included in the computation of the clock correction. After removing the above error factors, satellite clock corrections are computed for individual reference stations, and an average clock correction is formed for each of a plurality of satellites by taking an average or weighted average of the satellite clock corrections over reference stations to which the satellite is visible.

Abstract: The present invention includes a method for a combined use of a local RTK system and a regional, wide-area, or global differential carrier-phase positioning system (WADGPS) in which disadvantages associated with the RTK and the WADGPS navigation techniques when used separately are avoided. The method includes determining a floating ambiguity value and a first position of an object using WADGPS in a first mode of operation, and determining a second position of the object using the local RTK system in a second mode of operation.

Abstract: A method for generating an ambiguity-resolved, refraction-corrected, and noise-minimized carrier-phase measurement. The method includes forming a first composite measurement using GPS carrier-phase measurements on the L1, L2 and L5 frequencies. To reduce the noise in the first composite measurement, the method further includes forming a second composite measurement using GPS carrier-phase measurements on at least two of the three GPS carrier frequencies. The second composite measurement is formed to have a small multi-path noise therein so that it can be used to smooth the first composite measurement so that the multipath noise is minimized.

Abstract: A method for detecting and identifying a faulty measurement among a plurality of GPS measurements, obtained by a GPS receiver with respect to a plurality of satellites in view of the GPS receiver, determines whether the plurality of GPS measurements include a faulty measurement. In response to a determination that the plurality of GPS measurements include a faulty measurement, the method identifies a satellite contributing the faulty measurement by computing a correlation value associated with each of the plurality of satellites, and selecting a satellite associated with a highest correlation value as the satellite contributing the faulty measurement.

Abstract: A communication device includes a transmitter and receiver. The transmitter includes an M-ary encoder configured to generate an M−1 number of distinctive symbols each comprising k bits. M is equal to 2k and k is a positive integer. The transmitter also includes a code generator configured to produce spread spectrum codeword sequences based on the symbols generated by the M-ary encoder and based on a first and a second Gold code polynomials. The transmitter sends a radio signal based on the spread spectrum codeword sequences. The receiver is configured to receive the radio signal. The receiver includes a first shift register configured to receive an input signal generated based on the received radio signal and a second shift register configured to receive and circularly shift a locally generated codeword sequence that is identical to the codeword sequence used to encode the symbols.

Abstract: A method of fast GPS carrier phase integer ambiguity resolution is based on properties of a Residual Sensitivity Matrix (S matrix), which directly relates a set of integer ambiguities to carrier phase residuals. In one embodiment, the method uses the singular value decomposition of the S Matrix to split the integer ambiguity set into two integer ambiguity subsets and to derive a relationship between the two integer ambiguity subsets. Thus, searching for the integer ambiguity set is reduced to searching for one of the two integer ambiguity subsets, resulting in greatly reduced search space. In an alternative embodiment, a portion of the rows of the S matrix that are linearly independent rows are selected and the S matrix is rearranged according to the selection. The rearranged S matrix is then split into four sub-matrices, which are used to relate the two integer ambiguity subsets.

Abstract: A position tracking system for a plurality of mobile tractors and trailers includes an unique electronic identifier for each of a plurality of trailers. For each tractor of a plurality of tractors, the position tracking system includes a navigation system for determining a current position of the tractor, an electronic identifier reader for acquiring the electronic identifier of a trailer coupled to the tractor, and a position-reporting subsystem for reporting to a remote system the current position of the tractor and the electronic identifier of the trailer coupled to the tractor. In addition, the position tracking system includes, at each facility of a plurality of fixed-location facilities, one or more electronic identifier readers for acquiring the electronic identifier of one or more trailers located within the facility, and a trailer-presence reporting subsystem for reporting to the remote system the presence of the one or more trailers located within the facility.

Abstract: A two-way ultrasonic positioning and navigation system and method involve a plurality of objects each capable of transmitting and receiving ultrasonic signals. A first object transmits an initiating ultrasonic signal and identifies a second object for responding to the initiating ultrasonic signal. The second object transmits a responding ultrasonic signal after a predetermined time delay from receiving the initiating ultrasonic signal. The first objectives the responding ultrasonic signal, and determines a distance between the first object and the second object based on a time period starting at the transmission of the initiating ultrasonic signal and ending at the reception of the responding ultrasonic signal, and on knowledge about the predetermined time delay and other known in advance time delays.