Method and system for determining position using signals from satellites
First Claim
1. A method for determining position using carrier suppressed radio signals broadcast from a plurality of earth orbiting satellites, said method comprising:
- a. positioning an upward looking omni-directional antenna at a survey mark;
b. measuring the carrier phases implicit in the signals concurrently received from a plurality of the satellites independently of externally derived knowledge of the information content of the modulation thereof by cross-correlating spectral portions of such concurrently received signals, and thenc. processing the measurements to determine position information.
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0 Petitions
Accused Products
Abstract
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.
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Citations
81 Claims
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1. A method for determining position using carrier suppressed radio signals broadcast from a plurality of earth orbiting satellites, said method comprising:
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a. positioning an upward looking omni-directional antenna at a survey mark; b. measuring the carrier phases implicit in the signals concurrently received from a plurality of the satellites independently of externally derived knowledge of the information content of the modulation thereof by cross-correlating spectral portions of such concurrently received signals, and then c. processing the measurements to determine position information. - View Dependent Claims (2)
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3. A system for use in measuring position using radio signals broadcast from a plurality of earth orbiting satellites, and including a terminal adapted to be positioned at a point on earth, comprising:
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a. an upward looking omni-directional antenna assembly for concurrently receiving radio signals from a plurality of satellites, said antenna assembly including an antenna, and b. an electronic assembly for converting received carrier-suppressed signals into carrier phase data, said electronics assembly including; i. a receiver unit for receiving signals from the antenna assembly and outputting signals, representing the upper sideband component of the received signals, the lower sideband of the received signals, and the output of a reference oscillator; ii. a digital electronics unit for converting the output signals from the receiver unit into carrier phase data, and iii. a computer for processing said carrier phase data to determine position. - View Dependent Claims (4, 5)
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6. A method for determining position comprising the steps of:
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(a) receiving a composite of modulated, carrier-suppressed signals from a plurality of satellites at a first mark with an upward looking omni-directional antenna; (b) generating a first set of data representative of carrier phases implicit in said signals independently of externally derived knowIedge of the information content of the modulation thereof; (c) generating a second set of data related to a second mark; (d) processing said sets of data to determine the relative position of the marks. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. The method of determining position information from carrier suppressed signals transmitted concurrently with the same frequencies by a plurality of satellites, comprising:
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(a) collecting at a first mark a first composite signal simultaneously including components representing carrier suppressed signals received by an upward looking omni-directional antenna, from more than one of the satellites; (b) deriving therefrom data related to a selected carrier implicit in the signals received from a selected satellite, independently of externally derived knowledge of the information content of the modulation of that selected carrier; and (c) processing the data to determine position information. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A system for determining position information from carrier suppressed signals transmitted concurrently with the same frequencies by a plurality of satellites, comprising:
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(a) means for collecting at a first mark a first composite signal simultaneously including components representing carrier suppressed signals received from more than one of the satellites with an upward looking omni-directional antenna; (b) means for deriving, from the first composite signal, data related to a selected carrier implicit in the signals transmitted by a selected satellite, independently of externally derived knowledge of the information content of the modulation of that selected carrier; and (c) means for processing the data to determine position information. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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55. The method of determining position information from wide spectrum signals transmitted concurrently with the same frequencies by a plurality of satellites, comprising;
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(a) collecting at a first mark a first composite signal simultaneously including components representing signals having substantially overlapping wide spectra received from more than one of the satellites; (aa) reconstructing the first composite to form a second composite simultaneously including a plurality of reconstructed components; (b) using the frequency of a selected suppressed signal implicit in the signals received from a selected satellite to separate the component related to that satellite from other components of the second composite signal; and (c) processing the separated component to determine position information. - View Dependent Claims (56, 57, 58, 59, 60, 62, 64, 66, 67, 68, 69, 71, 72, 73, 74, 75, 77)
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- 61. (g) processing the components so separated from both marks to determine relative position.
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70. A system for determining position information from wide spectrum signals transmitted concurrently with the same frequencies by a plurality of satellites, comprising:
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(a) means for collecting at a first mark a first composite signal simultaneously including components representing signals having substantially overlapping wide spectra received from more than one of the satellites; (aa) means for reconstructing the first composite to form a second composite simultaneously including a plurality of reconstructed components; (b) means responsive to the first composite signal for separating the component related to a selected satellite from other components of the first composite signal by use of the frequency of a selected suppressed signal implicit in the signals from that satellite; (c) means for processing the component so separated to determine position information. - View Dependent Claims (76, 78, 79, 80, 81)
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Specification