GPS receiver and method for processing GPS signals
First Claim
1. A method for using a GPS receiver having a communication system, said method comprising:
- activating said GPS receiver in a first mode of operation which comprises;
receiving first GPS signals from in view satellites;
demodulating said first GPS signals to extract satellite information regarding in view satellites and computing pseudorange information for said in view satellites;
activating said GPS receiver in a second mode of operation which comprises;
receiving second GPS signals from in view satellites;
receiving non-differential GPS satellite assistance data from said communication system, wherein said non-differential GPS satellite assistance data comprises Doppler information for in view satellites;
processing said second GPS signals to determine pseudoranges to in view satellites.
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Accused Products
Abstract
A global positioning system (GPS) receiver has first circuitry for receiving and processing pseudorandom sequences transmitted by a number of GPS satellites. The first circuitry is configured to perform conventional correlation operations on the received pseudorandom sequences to determine pseudoranges from the GPS receiver to the GPS satellites. The GPS receiver also includes second circuitry coupled to the first circuitry. The second circuitry is configured to receive and process the pseudorandom sequences during blockage conditions. The second circuitry processes the pseudorandom sequences by digitizing and stoning a predetermined record length of the received sequences and then performing fast convolution operations on the stored data to determine the pseudoranges. The GPS receiver may have a common circuitry for receiving GPS signals from in view satellites and downconverting the RF frequency of the received GPS signals to an intermediate frequency (IF). The IF signals are split into two signal paths; a first of which provides the conventional con-elation processing to calculate the pseudoranges. During blockage conditions, the IF signal is passed to the second signal path wherein the IF signals are digitized and stored in memory and later processed using the fast convolution operations to provide the pseudoranges. Alternative arrangements for the two signal paths include separate downconverters or shared digitizers. One embodiment provides both signal paths on a single integrated circuit with shared circuitry executing computer readable instructions to perform GPS signal processing appropriate to the reception conditions.
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Citations
12 Claims
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1. A method for using a GPS receiver having a communication system, said method comprising:
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activating said GPS receiver in a first mode of operation which comprises; receiving first GPS signals from in view satellites; demodulating said first GPS signals to extract satellite information regarding in view satellites and computing pseudorange information for said in view satellites; activating said GPS receiver in a second mode of operation which comprises; receiving second GPS signals from in view satellites; receiving non-differential GPS satellite assistance data from said communication system, wherein said non-differential GPS satellite assistance data comprises Doppler information for in view satellites; processing said second GPS signals to determine pseudoranges to in view satellites. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A dual mode receiver comprising:
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a communication system for receiving non-differential GPS satellite assistance data; a GPS receiver coupled to said communication system, said GPS receiver having a first mode of operation and a second mode of operation, in said first mode said GPS receiver receives first GPS signals from in view satellites and demodulates said first GPS signals to extract satellite information regarding in view satellites and computes pseudorange information for said in view satellites, and in said second mode said GPS receiver receives second GPS signals from in view satellites and receives said non-differential GPS satellite assistance data from said communication system and processes said second GPS signals to determine pseudorange to in view satellites, wherein said non-differential GPS satellite assistance data comprises Doppler information for in view satellites. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification