US5048053A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Detecting and tracking circuit for component PN codes
Assignee: Unisys Corp
•
Filing: 1989-11-20
•
Granted: 1991-09-10
•
Expires: 2009-11-20
Abstract
Abstract In a demodulator circuit for receiving a direct sequence spread spectrum signal having composite PN codes, there is provided a novel detecting and tracking circuit for faster acquisition of the component PN codes. The first component code of the received composite direct sequence spread spectrum code is noncoherently detected in a noncoherent detection branch and the subsequent component codes of the composite code are automatically detected in a coherent lock detection branch to provide faster acquisition than was heretofore possible. Further, while the noncoherent detection branch is acquiring the first component PN code, a novel coherent carrier tracking loop is acquiring and locking onto the direct sequence spread spectrum signal carrier.
Inventors
- 👤 Vaughn L. Mower
- 👤 John W. Zscheile, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:06
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/7073; H04B1/7075; H04B1/708; H04B1/7085; H04B1/70735
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
201 words
A detection and tracking circuit for fast acquisition of a PN composite code composed of PN component codes, comprising: a first correlator/mixer having an input coupled to receive a signal containing a down converted PN composite code, a PN generator having a first PN, component code output and a second component code PN X output for producing PN 2 to PN N component codes, said PN 1 code output being coupled to said first correlator/mixer for producing a data modulated IF carrier signal output, coupled to an input of second correlator/mixer and to a coherent carrier tracking loop, said second correlator/mixer having an input coupled to said PN X output from said PN generator and an output coupled to a down converter/mixer which provides a baseband data bearing signal output, said baseband data bearing signal output being coupled to a noncoherent detection branch and to a coherent lock detection branch, said noncoherent detection branch providing means for detecting the alignment of said first PN 1 component code with said PN composite code to be acquired, and said coherent lock detection branch providing means for coherently detecting alignment of said PN 2 to PN N component codes with said PN composite code.
Claim 2
Dependent Claim
201 words
A detection and tracking circuit for fast acquisition of a PN composite code composed of PN component codes, comprising: a first correlator/mixer having an input coupled to receive a signal containing a down converted PN composite code, a PN generator having a first PN, component code output and a second component code PN X output for producing PN 2 to PN N component codes, said PN 1 code output being coupled to said first correlator/mixer for producing a data modulated IF carrier signal output, coupled to an input of second correlator/mixer and to a coherent carrier tracking loop, said second correlator/mixer having an input coupled to said PN X output from said PN generator and an output coupled to a down converter/mixer which provides a baseband data bearing signal output, said baseband data bearing signal output being coupled to a noncoherent detection branch and to a coherent lock detection branch, said noncoherent detection branch providing means for detecting the alignment of said first PN 1 component code with said PN composite code to be acquired, and said coherent lock detection branch providing means for coherently detecting alignment of said PN 2 to PN N component codes with said PN composite code.
Claim 3
Dependent Claim
33 words
A detecting and tracking circuit as set forth in claim 1 wherein said data modulated IF carrier signal output is further coupled to a data demodulator for producing a sequence of data signals.
Claim 4
Dependent Claim
33 words
A detecting and tracking circuit as set forth in claim 1 wherein the output of said coherent carrier tracking loop is coupled to a data demodulator for producing a sequence of data signals.
Claim 5
Dependent Claim
32 words
A detecting and tracking circuit as set forth in claim 3 wherein said output of said coherent carrier tracking loop is further coupled to said down converter/mixer through a quadrature phase shifter.
Claim 6
Dependent Claim
33 words
A detecting and tracking circuit as set forth in claim 1 wherein said data modulated IF carrier signal output is further coupled to a code tracking loop for producing a PN clock signal.
Claim 7
Dependent Claim
43 words
A detecting and tracking circuit as set forth in claim 1 wherein of said noncoherent and said coherent detecting branches are provided with outputs coupled to a search controller for producing command control signals which control a search sequence of said PN generator.
Claim 8
Dependent Claim
51 words
A detecting and tracking circuit as set forth in claim 6 wherein said PN generator produces a PN 1 component code for a first PN 1 search sequence at the input of said first correlator/mixer and produces an enable PN X component code signal at the input of said second correlator/mixer.
Claim 9
Dependent Claim
60 words
A detecting and tracking circuit as set forth in claim 7 wherein the second and subsequent PN 2 to PN N component codes are searched by said PN generator to produce a PN 1 component code at the input of said first correlator/mixer and produce PN 2 to PN N component codes, respectively, at the input of said second correlator/mixer.
Claim 10
Dependent Claim
30 words
A detection and tracking circuit as set forth in claim 1 wherein said noncoherent detecting branch comprises a low pass filter coupled to the baseband output of said down converter/mixer.
Claim 11
Dependent Claim
32 words
A detecting and tracking circuit as set forth in claim 1 which further comprises means for A.C. coupling the output of said down converter/mixer to said noncoherent and said coherent detection branches.
Claim 12
Dependent Claim
44 words
A detecting and tracking circuit as set forth in claim 10 wherein said means for A.C. coupling the output of said down converter/mixer comprises an amplifier and a capacitor in series with a multiplier for reducing D.C. noise offset produced by the down converter/mixer.
Claim 13
Dependent Claim
47 words
A detecting and tracking circuit as set forth in claim 11 which further includes a predetermined clock signal synchronized with the incoming PN 1 signal from said PN generator is coupled to an input of said multiplier for restoring the error signal produced by the down converter/mixer.
Claim 14
Dependent Claim
31 words
A detecting and tracking circuit as set forth in claim 12 wherein said predetermined clock signal is a Manchester coded clock signal synchronized with the first component code PN 1 .
Claim 15
Dependent Claim
34 words
A detecting and tracking circuit as set forth in claim 1 which further comprises means for A.C. coupling the IF carrier signal output of from said first correlator/mixer to said coherent carrier tracking loop.
Claim 16
Dependent Claim
32 words
A detecting and tracking circuit as set forth in claim 14 wherein said means for A.C. coupling the output of said mixer comprises an amplifier, a capacitor, and a multiplier in series.
Claim 17
Dependent Claim
43 words
A detecting and tracking circuit as set forth in claim 1 which further includes a frequency offset loop embedded in series in said coherent carrier tracking loop for providing means for compensating for doppler frequency shift of the PN composite code being received.
Claim 18
Dependent Claim
30 words
A detecting and tracking circuit as set forth in claim 16 wherein said frequency offset loop comprises means for presenting doppler error correction information into said coherent carrier tracking loop.
Claim 19
Dependent Claim
23 words
A detecting and tracking circuit as set forth in claim 17 wherein said frequency offset loop comprises a highly accurate reference frequency source.
Claim 20
Dependent Claim
48 words
A detecting and tracking circuit as set forth in claim 18 wherein said frequency offset loop further includes a pair of dividers for coupling the output of said frequency reference source and said means for presenting doppler error correction information to a highly accurate voltage controlled crystal oscillator.
References Cited (Backward Citations)
US4638494A
Cited
US4776012A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-09 | 1995-03-11 | 1995-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-09 | 1999-03-11 | 1999-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-09 | 2003-03-11 | 2003-09-10 | $7700.00 | Window Closed / Lapsed |