Method and apparatus are disclosed for accurately determining position from GPS satellites and received on a ship using C/A code group delay observable TAU, 308 f o implicit carrier phase observable PHI, L1 band implicit f o carrier residual phase observable PSI L1 , and L2 band implicit f o carrier residual phase observable PSI L2 . A precise measurement of the group-phase delay range to each satellite is made based upon the L1 center frequency carrier phase. A correction for ionospheric effects is determined by simultaneous observation of the group delays of the wide bandwidth P code modulations in both the L1 and L2 bands. These group delays are determined by measuring the phases of carrier waves implicit in the spread-spectrum signals received in both bands. These carriers are reconstructed from both the L1 and L2 band signals from each satellite without using knowledge of the P code. The unknown biases in the L1 center frequency carrier phase range measurements are determined from simultaneous, pseudorange measurements, with time averaging. The instantaneous position of the ship may then be determined from the ranges so determined, with both the bias and the ion-spheric effects having been eliminated.

Method and system for determining position on a moving platform, such as a ship, using signals from GPS satellites

Method and apparatus are disclosed for accurately determining position from GPS satellites and received on a ship using observations of C/A code group delay, L1 band center frequency carrier phase, L1 band 5115 MHz implicit carrier phase, and L2 band 5115 MHz implicit carrier phase A precise measurement of the range to each satellite is made based upon the L1 center frequency carrier phase A correction for ionospheric effects is determined by simultaneous observation of the group delays of the wide bandwidth P code modulations in both the L1 and L2 bands These group delays are determined by measuring the phases of carrier waves implicit in the spread-spectrum signals received in both bands These carriers are reconstructed from both the L1 and L2 band signals from each satellite without using knowledge of the P code The unknown biases in the L1 center frequency carrier phase range measurements are determined from simultaneous, pseudorange measurements, with time averaging The instantaneous position of the antenna receiving these signals, and therefore the ship, may then be determined from the ranges so determined, with both the bias and the ionospheric effects having been eliminated Additional antennas are positioned on the ship and a seismic streamer towed by the ship to reject false signals, compensate for blockage of signals by the ship's structure, and determine the position of sensors in the streamer

Multi-antenna gas receiver for seismic survey vessels

A method and a system are disclosed for measuring the baseline vector b between a pair of survey marks on the ground by radio interferometry using radio signals broadcast from the earth orbiting satellites of the NAVSTAR Global Positioning System (GPS), the radio signals broadcast by the satellites being double-sideband modulated with their carriers suppressed. An antenna is positioned at each survey mark. The signals received by one antenna during a predetermined time span are separated into upper and lower sideband components. These separate components are filtered, converted to digital form, and then multiplied together. Their product is analyzed digitally by means of correlation with quadrature outputs of a local oscillator to determine the power, and the phase relative to that local oscillator, of the carrier wave that is implicit in the double-sideband signal being received from each satellite. Differences in Doppler shift are utilized to distinguish the carriers of different satellites. The signals received at the same time by the other antenna are processed in the same manner. Thus, the powers and carrier phases of the signals from a plurality of satellites are measured simultaneously and numerical data representing the measurement results are obtained at each survey mark. The measurements are performed in real time at each mark without reference to signals that are received at any other place and without knowledge of any of the coded signals that modulate the GPS carriers. The data from the measurements performed simultaneously but independently at the two survey marks.

Method and system for determining position using signals from satellites

A method and a system are disclosed for measuring the baseline vector b between a pair of survey marks on the ground by radio interferometry using radio signals broadcast from the earth orbiting satellites of the NAVSTAR Global Positioning System (GPS), the radio signals broadcast by the satellites being double-sideband modulated with their carriers suppressed The signals received by one antenna during a predetermined time span are separated into upper and lower sideband components These separate components are filtered, converted to digital form, and then multiplied together Differences in Doppler shift are utilized to distinguish the carriers of different satellites Thus, the powers and carrier phases of the signals from a plurality of satellites are measured simultaneously and numerical data representing the measurement results are obtained at each survey mark The measurements are performed in real time at each mark without reference to signals that are received at any other place and without knowledge of any of the coded signals that modulate the GPS carriers

System for simultaneously deriving position information from a plurality of satellite transmissions

A method and a system are disclosed for measuring the baseline vector b between a pair of survey marks on the ground by radio interferometry using radio signals broadcast from the earth orbiting satellites of the NAVSTAR Global Positioning System (GPS), the radio signals broadcast by the satellites being double-sideband modulated with their carriers suppressed An antenna is positioned at each survey mark The signals received by one antenna during a predetermined time span are separated into upper and lower sideband components These separate components are filtered, converted to digital form, and then multiplied together Their product is analyzed digitally by means of correlation with quadrature outputs of a local oscillator to determine the power, and the phase relative to that local oscillator, of the carrier wave that is implicit in the double-sideband signal being received from each satellite Differences in Doppler shift are utilized to distinguish the carriers of different satellites The signals received at the same time by the other antenna are processed in the same manner Thus, the powers and carrier phases of the signals from a plurality of satellites are measured simultaneously and numerical data representing the measurement results are obtained at each survey mark The measurements are performed in real time at each mark without reference to signals that are received at any other place and without knowledge of any of the coded signals that modulate the GPS carriers The data from the measurements performed simultaneously but independently at the two survey marks, once per second for a predetermined time span, are then processed together to determine the baseline vector that extends from one mark to the other Two methods of processing are disclosed In either method, an "ambiguity function", is computed which is a function of the measurement data and of a trial value b of the baseline vector The vector space of b is systematically searched to find the unique value of b that maximizes the computed function This value of b is taken to be the desired determination of b By using signals from a plurality of five satellites and a time span of about 5000 seconds, a baseline vector determination can be obtained by the method of the present invention with an accuracy of about 5 millimeters in each coordinate for a baseline length of about 100 meters

Method and system for determining position from signals from satellites

A radar system for determining the position of a target using a radio frency source of opportunity. The system uses an interferometer antenna and cross-correlation techniques to measure the time delay in receiving a reflected signal from the target as compared to receiving a direct signal from the signal source. Thereby, the distance from the RF source via the target to the antenna is determined. Additionally, the system uses a plurality of interferometer antennas and cross-correlation techniques to measure the relative phase difference between the signals received by the antennas. Thereby the angle of arrival of the reflected signals from the target is determined. Combining the range and angular information locates the target.

Dual base line interferometer antenna

A system for quasi real-time computer aided characterization of symmetrical-way microwave power combining structures which utilizes a network analyzer to measure scattering parameters of said combining structure at various RF frequencies and at desired transmission routes through said combining structure. The routes are selected by a coaxial switching network which is controlled by said network analyzer which also computes and outputs the maximum combining efficiency, η, and the input impedance of the ith port under conditions of maximum combining efficiency, Zic.

Marko Afendykiw

Papers

Dual base line interferometer antenna

N-way summing network characterization system