Sequencer for a shared channel global positioning system receiver
First Claim
1. A shared channel Global Positioning System (GPS) receiver for receiving a plurality of coded satellite signals from a plurality of satellites, said signals exhibiting Doppler shifting, said GPS receiver comprising:
- means for converting said coded satellite signals to intermediate frequency signals;
A/D means coupled to said means for converting, said A/D means for simultaneously translating said intermediate frequency signals for said plurality of coded satellite signals to a plurality of digital signals;
correlation means coupled to said A/D means, said correlation means for simultaneously separating each of said plurality of digital signals corresponding to each said satellite to provide channel information signals for each said satellite;
channel means coupled to said correlation means, said channel means for estimating a plurality of parameters describing each satellite'"'"'s expected position and an expected frequency of transmission of said coded satellite signals including Doppler compensation for each of said plurality of said satellites on a time division multiplexed basis; and
processor means coupled to said correlation means and to said channel means, said processor means for retrieving information transmitted from each of said satellites in response to channel information signals.
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Abstract
A shared channel GPS (Global Positioning System) receiver for receiving a plurality of coded satellite signals. The plurality of satellite signals is transmitted by a corresponding plurality of satellites. Since these satellites are moving rapidly with respect to the receiver, Doppler shifting of the signals is exhibited. The signals are converted from analog to digital at intermediate frequency levels. The signals are then separated simultaneously into a plurality of digital signals corresponding to channel information for each transmitting satellite. One channel of the receiver sequence through a number of the satellites on a time division multiplexed basis. The channel estimates a plurality of parameter pertaining to each satellite so that re-acquisition of the satellite'"'"'s transmission may be facilitated. A processor then converts these channel information signals to pseudo-range and broadcast data for navigation and time purposes.
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Citations
32 Claims
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1. A shared channel Global Positioning System (GPS) receiver for receiving a plurality of coded satellite signals from a plurality of satellites, said signals exhibiting Doppler shifting, said GPS receiver comprising:
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means for converting said coded satellite signals to intermediate frequency signals; A/D means coupled to said means for converting, said A/D means for simultaneously translating said intermediate frequency signals for said plurality of coded satellite signals to a plurality of digital signals; correlation means coupled to said A/D means, said correlation means for simultaneously separating each of said plurality of digital signals corresponding to each said satellite to provide channel information signals for each said satellite; channel means coupled to said correlation means, said channel means for estimating a plurality of parameters describing each satellite'"'"'s expected position and an expected frequency of transmission of said coded satellite signals including Doppler compensation for each of said plurality of said satellites on a time division multiplexed basis; and processor means coupled to said correlation means and to said channel means, said processor means for retrieving information transmitted from each of said satellites in response to channel information signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A multiplexed sequential scanning method for use in a shared channel GPS receiver which receives a plurality of coded satellite signals from a plurality of satellites, the signals exhibiting Doppler shifting, the shared channel GPS receiver including a processor, random access memory (RAM), read only memory (ROM), and numerically controlled oscillator (NCO), a shared channel, and a code generator, the processor performing the multiplexed sequential scanning method comprising the steps of:
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determining by the shared channel an estimated pseudorange for a satellite being scanned; determining by the shared channel an estimated code position for the satellite being scanned; determining by the shared channel an estimated NCO phase; determining by the shared channel an estimated NCO frequency; and iterating said steps of determining an estimated pseudorange, determining an estimated code position, determining an estimated NCO phase and determining an estimated NCO frequency for each of said plurality of satellites on a time division multiplexed basis. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. In a Global Positioning System (GPS), a GPS receiver for receiving a plurality of coded satellite signals from a plurality of satellites, said signals exhibiting Doppler shifting, said GPS receiver comprising:
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means for converting said coded satellite signals to intermediate frequency signals; A/D means coupled to said means for converting, said A/D means for simultaneously translating said intermediate frequency signals for said plurality of coded satellite signals to a plurality of digital signals; correlation means coupled to said A/D means, said correlation means for simultaneously separating each of said plurality of digital signals corresponding to each said satellite to provide channel information signals for each said satellite; first channel means coupled to said correlation means, said first channel means for continuously receiving said coded satellite signals from a particular one of said plurality of satellites for a period; second channel means coupled to said correlation means, said channel means for estimating a plurality of parameters describing said satellite'"'"'s expected position and an expected frequency of transmission of said coded satellite signals including Doppler compensation for all of said plurality of said satellites except said particular one of said satellites on a time division multiplexed basis; and processor means coupled to said correlation means and to said first and second channel means, said processor means for retrieving information transmitted from each of said satellites in response to channel information signals. - View Dependent Claims (32)
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Specification