Method and system for data detection in a global positioning system satellite receiver
First Claim
1. A GPS receiver, comprising:
- a radio frequency system receiving GPS signals from GPS satellites and providing digitized signals of a complex format derived from the GPS signals, wherein the GPS signal from each satellite comprises a spread spectrum modulated signal encoding a data signal, each bit of the data signal spanning a predetermined data epoch;
a digital memory including a plurality of buffers for storing the digitized signals, each buffer having a predetermined size to hold digitized signals received over a time period exceeding the predetermined epoch of the data signal, the digital memory organized such that, at any given time, the digitized signals in a first one of the buffers is made available for retrieval, while the digitized signals from the radio frequency system is received into a second one of the buffers; and
a digital processor coupled to the digital memory, wherein the digital processor processes the digitized signals retrieved from the digital memory to provide a de-spreaded digitized signal, and wherein the digital processor further comprisesdata detection circuitry configured to decode the data signal from the de-spreaded over successive data epochs.
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Accused Products
Abstract
A data detection circuit within a global positioning system (GPS) satellite receiver operates to detect and decode data sent in a spread spectrum signal. The data detection circuit receives input from a radio receiver, the information containing data from a plurality of satellites. The data is supplied to a circular memory device, which determines which data corresponds to which satellite. The memory device sends the received signal to a matched filter, which decodes the signal received from each satellite. This signal is analyzed to determine whether a phase inversion due to data modulation on the received signal is present. The phase inversion can occur at boundaries, known as data epochs, in the received signal, and corresponds to data in the received signal. This data contains information relating to the position of each satellite and is collected by the data detection circuit for use by the GPS receiver.
152 Citations
8 Claims
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1. A GPS receiver, comprising:
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a radio frequency system receiving GPS signals from GPS satellites and providing digitized signals of a complex format derived from the GPS signals, wherein the GPS signal from each satellite comprises a spread spectrum modulated signal encoding a data signal, each bit of the data signal spanning a predetermined data epoch; a digital memory including a plurality of buffers for storing the digitized signals, each buffer having a predetermined size to hold digitized signals received over a time period exceeding the predetermined epoch of the data signal, the digital memory organized such that, at any given time, the digitized signals in a first one of the buffers is made available for retrieval, while the digitized signals from the radio frequency system is received into a second one of the buffers; and a digital processor coupled to the digital memory, wherein the digital processor processes the digitized signals retrieved from the digital memory to provide a de-spreaded digitized signal, and wherein the digital processor further comprises data detection circuitry configured to decode the data signal from the de-spreaded over successive data epochs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification