Patent US5003552A successfully refreshed from Google Patents.
US5003552A
Expired / Lapsed
US
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Carrier aided code tracking loop
Assignee: Unisys Corp
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Filing: 1989-11-20
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Granted: 1991-03-26
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Expires: 2009-11-20
Abstract
Abstract A fast acquisition coherent code tracking loop for use in direct sequence spread spectrum systems is provided with an embedded frequency offset loop. The frequency offset loop in the code tracking loop is provided with a pair of multipliers, one of which is coupled to the carrier tracking loop through a scaling circuit and the second multiplier is coupled to the output of the highly stable VCO of the carrier tracking loop to provide extremely fast phase acquisition of the received PN code and very high frequency stability of the code tracking loop.
Inventors
- 👤 Vaughn L. Mower
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:49
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/707
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
174 words
A fast acquisition coherent code tracking loop of the type employed to produce a synchronized PN clock from a received PN code signal, comprising: a PN generator for generating a PN replica code, a code alignment detector coupled to receive said received PN code signal and coupled to said PN generator for providing an unfiltered error signal indicative of the phase offset between the received PN code signal and said PN replica code, a loop filter coupled to receive said unfiltered error signal for producing a phase offset error signal, frequency offset loop means, an accurate VCO having its input port coupled to receive said phase offset error signal and its output port coupled in series with said frequency offset loop means and to said PN generator, a coherent carrier tracking loop for producing an I.F. carrier frequency signal, and scaling means in said coherent carrier tracking loop for injecting scaled carrier tracking loop correction information into said frequency offset loop means to enhance the speed of acquisition of said received PN code signal.
Claim 2
Dependent Claim
174 words
A fast acquisition coherent code tracking loop of the type employed to produce a synchronized PN clock from a received PN code signal, comprising: a PN generator for generating a PN replica code, a code alignment detector coupled to receive said received PN code signal and coupled to said PN generator for providing an unfiltered error signal indicative of the phase offset between the received PN code signal and said PN replica code, a loop filter coupled to receive said unfiltered error signal for producing a phase offset error signal, frequency offset loop means, an accurate VCO having its input port coupled to receive said phase offset error signal and its output port coupled in series with said frequency offset loop means and to said PN generator, a coherent carrier tracking loop for producing an I.F. carrier frequency signal, and scaling means in said coherent carrier tracking loop for injecting scaled carrier tracking loop correction information into said frequency offset loop means to enhance the speed of acquisition of said received PN code signal.
Claim 3
Dependent Claim
57 words
A fast acquisition coherent code tracking loop as set forth in claim 1 wherein said frequency offset loop means comprises a first multiplier in series in said frequency offset loop means and having a negative input port coupled to the output port of said scaling means for introducing doppler error correction information into said code tracking loop.
Claim 4
Dependent Claim
58 words
A fast acquisition coherent code tracking loop as set forth in claim 2 wherein said frequency offset loop means comprises a second multiplier in series in said frequency offset loop means and having a positive input port coupled to the output of said accurate VCO in said code tracking loop for enhancing stability of said code tracking loop.
Claim 5
Dependent Claim
30 words
A fast acquisition coherent code tracking loop as set forth in claim 1 wherein said frequency offset loop means further comprises phase/frequency comparator means in said frequency offset loop means.
Claim 6
Dependent Claim
28 words
A fast acquisition coherent code tracking loop as set forth in claim 4 which further comprises a highly accurate frequency reference source coupled to said phase/frequency comparator means.
Claim 7
Dependent Claim
31 words
A fast acquisition coherent code tracking loop as set forth in claim 5 which further includes a frequency divider in series between said frequency reference source and said phase/frequency comparator means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-03-25 | 1994-09-24 | 1995-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-03-25 | 1998-09-24 | 1999-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-03-25 | 2002-09-24 | 2003-03-26 | $7700.00 | Window Closed / Lapsed |