Global positioning system course acquisition code receiver
First Claim
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1. A GPS satellite receiver for locking to a satellite signal, the receiver comprising in combination:
- means for receiving the satellite signal;
first coupling means;
down-converting means connected to said receiving means by said first coupling means, said down-converting means for down converting to a first frequency the frequency of a signal developed from said received satellite signal;
second coupling means;
a hard limiter connected to said down-converting means by said second coupling means, said hard limiter for converting from analog-to-digital form a signal developed from said down-converted satellite signal;
third coupling means;
carrier-synthesizer means for generating a first signal having a frequency established by carrier-synthesizer-means-driving signals;
Q-counter means connected to said hard limiter by said third coupling means and connected to said carrier-synthesizer means, said Q-counter means for developing signals representing a count which is incremented at each of a series of times marked by said first carrier-synthesizer-means-generated signal when a signal developed from a signal developed by said hard limiter has a predetermined one of two states and decremented at each of said first carrier-synthesizer-means-generated-signal marked times otherwise; and
controller means connected to said carrier-synthesizer means and connected to said Q-counter means, said controller means being responsive to said Q-counter-means-developed signals and operative to develop said carrier-synthesizer-means-driving signals so as to lock the frequency of said first carrier-synthesizer-means-generated signal to said down-converter-means first frequency.
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Abstract
A GPS satellite receiver is disclosed in which the frequency of the received satellite signal is down converted in a single step by a balanced mixer driven by a half-frequency local oscillator and the down-converted satellite signal is converted from analog-to-digital form by a hard limiter.
281 Citations
7 Claims
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1. A GPS satellite receiver for locking to a satellite signal, the receiver comprising in combination:
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means for receiving the satellite signal; first coupling means; down-converting means connected to said receiving means by said first coupling means, said down-converting means for down converting to a first frequency the frequency of a signal developed from said received satellite signal; second coupling means; a hard limiter connected to said down-converting means by said second coupling means, said hard limiter for converting from analog-to-digital form a signal developed from said down-converted satellite signal; third coupling means; carrier-synthesizer means for generating a first signal having a frequency established by carrier-synthesizer-means-driving signals; Q-counter means connected to said hard limiter by said third coupling means and connected to said carrier-synthesizer means, said Q-counter means for developing signals representing a count which is incremented at each of a series of times marked by said first carrier-synthesizer-means-generated signal when a signal developed from a signal developed by said hard limiter has a predetermined one of two states and decremented at each of said first carrier-synthesizer-means-generated-signal marked times otherwise; and controller means connected to said carrier-synthesizer means and connected to said Q-counter means, said controller means being responsive to said Q-counter-means-developed signals and operative to develop said carrier-synthesizer-means-driving signals so as to lock the frequency of said first carrier-synthesizer-means-generated signal to said down-converter-means first frequency. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A GPS satellite receiver for locking to a satellite signal, the receiver comprising in combination:
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means for receiving the satellite signal; first coupling means; down-converting means connected to said receiving means by said first coupling means, said down-converting means for down converting to a first frequency the frequency of a signal developed from said received satellite signal; second coupling means; carrier-synthesizer means for generating a first signal having a frequency established by carrier-synthesizer-means-driving signals; Q-counter means connected to said down-converting means by said second coupling means and connected to said carrier-synthesizer means, said Q-counter means for developing signals representing a count which is incremented at each of a series of times marked by said first carrier-synthesizer-means-generated signal when a signal developed from said down-converted satellite signal has a predetermined one of two states and decremented at each of said first carrier-synthesizer-means-generated-signal marked times otherwise; and controller means connected to said carrier-synthesizer means and connected to said Q-counter means, said controller means being responsive to said Q-counter-means-developed signals and operative to develop said carrier-synthesizer-means-driving signals so as to lock the frequency of said first carrier-synthesizer-means-generated signal to said first down-converter-means frequency.
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Specification