System for simultaneously deriving position information from a plurality of satellite transmissions
First Claim
1. A method of determining position information from a composite of spread spectrum, suppressed carrier signals transmitted simultaneously at the same frequencies by a plurality of orbiting satellites and received simultaneously from different directions by an antenna, comprising:
- (a) forming a digital representation of said composite;
(b) applying said digital representation to a plurality of logic circuits, each said logic circuit being responsive to the signal transmitted by a different selected satellite and operating synchronously in response to a common clock;
(c) deriving simultaneously, in each said logic circuit, data representing the signal transmitted by the satellite to which each said logic circuit is responsive; and
(d) combining the simultaneously derived data from a plurality of said logic circuits to determined position information.
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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. 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.
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Citations
12 Claims
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1. A method of determining position information from a composite of spread spectrum, suppressed carrier signals transmitted simultaneously at the same frequencies by a plurality of orbiting satellites and received simultaneously from different directions by an antenna, comprising:
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(a) forming a digital representation of said composite; (b) applying said digital representation to a plurality of logic circuits, each said logic circuit being responsive to the signal transmitted by a different selected satellite and operating synchronously in response to a common clock; (c) deriving simultaneously, in each said logic circuit, data representing the signal transmitted by the satellite to which each said logic circuit is responsive; and (d) combining the simultaneously derived data from a plurality of said logic circuits to determined position information. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus for determining position information from a composite of spread spectrum, suppressed carrier signals transmitted simultaneously at the same frequencies by a plurality of orbiting satellites and received simultaneously from different directions by an antenna, comprising:
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(a) means for forming a digital representation of said composite; (b) a plurality of logic circuits operating synchronously in response to a common clock, each said logic circuit being responsive to a signal transmitted by a different selected satellite included in said digital representation; (c) means in each said logic circuit for deriving simultaneously data representing the signal transmitted by the satellite to which each said logic circuit is responsive; and (d) means for combining the simultaneously derived data from a plurality of said logic circuits to determine position information. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification