US4754465A
Expired / Lapsed
US
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Global positioning system course acquisition code receiver
Assignee: Trimble Inc
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Filing: 1984-05-07
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Granted: 1988-06-28
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Expires: 2004-05-07
Abstract
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.
Inventors
- 👤 Charles R. Trimble
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:03
CPC Classifications
G; G01; G01S; G01S19/00; G01S19/01; G01S19/13; G01S19/24; H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/099; H03L7/0991
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
225 words
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.
Claim 2
Dependent Claim
225 words
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.
Claim 3
Dependent Claim
112 words
A receiver as recited in claim 1 wherein said down-converting means includes local-oscillator means for generating a signal having a frequency one-half the frequency of a predetermined one of the two frequencies which differ from the frequency of said received-satellite signal by said first down-converter-means frequency and a balanced mixer connected to said local-oscillator means, connected to said receiving means by said first coupling means and connected to said hard limiter by said second coupling means, said balanced mixer for developing a signal by doubling the frequency of said local-oscillator-means-generated signal and for mixing said doubled-frequency signal with said signal developed from said received satellite signal to develop said down-converted satellite signal.
Claim 4
Dependent Claim
27 words
A receiver as recited in claim 2 wherein said first coupling means includes means for filtering and amplifying said received satellite signal to develop said down-converting-means-driving signal.
Claim 5
Dependent Claim
27 words
A receiver as recited in claim 2 wherein said second coupling means includes means for filtering and amplifying said down-converted satellite signal to develop said hard-limiter-driving signal.
Claim 6
Dependent Claim
110 words
A receiver as recited in claim 2 wherein said carrier-synthesizer means further generates a second signal which is in phase quadrature with said first carrier-synthesizer-means-generated-signal and wherein the receiver further comprises I-counter means connected to said hard limiter by said third coupling means, connected to said carrier-synthesizer means and connected to said controller means, said I-counter means for developing controller-means-driving signals representing a count which is incremented at each of a series of times marked by said second carrier-synthesizer-means-generated signal when said signal developed from said signal developed by said hard limiter has a predetermined one of two states and decremented at each of said second carrier-synthesizer-means-generated-signal marked times otherwise.
Claim 7
Dependent Claim
185 words
A receiver as recited in claim 2 wherein said satellite signal is biphase modulated by a PRN code, wherein said third coupling means includes PRN-code-synthesizer means for generating an early, a punctual and a late signal each representing said PRN code and each having a phase established by PRN-code-synthesizer-means-driving signals and exclusive-OR-gate means connected to said PRN-code-synthesizer means, connected to said hard limiter and connected to said Q-counter means, said exclusive-OR-gate means for comparing the state of said hard-limiter-developed signal with the state of said punctual-PRN-code-synthesizer-means-generated signal to develop said Q-counter-means-driving signal, wherein the receiver further comprises early/late means connected to said PRN-code synthesizer, connected to said hard limiter and connected to said controller means, said early/late means for comparing the state of said hard-limiter-developed signal with the state of said early and said late-PRN-code-synthesizer-means-developed signals to develop controller-means-driving signals representing the difference between an early and a late count, and wherein said controller means is further responsive to said early/late-means-developed signals and operative to develop said PRN-code-synthesizer-means-driving signals so as to lock the phase of said PRN-code-synthesizer-developed signals to said satellite signal PRN-code phase.
Claim 8
Dependent Claim
190 words
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; 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.
Claim 9
Dependent Claim
190 words
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; 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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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-06-28 | 1991-12-28 | 1992-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-06-28 | 1995-12-28 | 1996-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-06-28 | 1999-12-28 | 2000-06-28 | $7700.00 | Window Closed / Lapsed |