US5544200A
Expired / Lapsed
US
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Acquisition of carrier phase and symbol timing through joint estimation of phase and timing adjustments
Assignee: Linkabit Wireless Inc
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Filing: 1994-12-08
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Granted: 1996-08-06
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Expires: 2014-12-08
Abstract
Abstract A signal acquisition system rapidly acquires carrier phase and symbol timing of a received PSK-modulated communication signal having a 110-symbol pattern through joint estimation of carrier-phase adjustment and symbol-timing adjustment by processing a common set of sampled data. A reference signal at a local oscillator frequency is mixed with a received communication signal to provide the communication signal at an intermediate frequency. The intermediate-frequency communication signal is converted into a digital communication signal, which is formatted into in-phase (I) and quadrature-phase (Q) components. A sampling circuit samples the I components at twice a predetermined symbol rate to provide a first series of I-component samples at the predetermined symbol rate and a second series of I-component samples that are intermediate to the first series of I-component samples and at the predetermined symbol rate, and for sampling the Q components at twice the predetermined symbol rate to provide a first series of Q-component samples at the predetermined symbol rate and a second series of Q-component samples that are intermediate to the first series of Q-component samples and at the predetermined symbol rate. A processor processes the samples to estimate a phase-adjustment value and a symbol-timing-adjustment value. The phase of the reference signal is adjusted in accordance with the phase-adjustment value and the timing of the sampling is adjusted in accordance with the symbol-timing-adjustment value.
Inventors
- 👤 Song H. An
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:08
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/18; H04L27/22; H04L27/227; H04L27/2271; H04L27/2272; H04L7/00; H04L7/02; H04L7/033; H04L7/0334
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
233 words
A system for acquiring carrier phase and symbol timing of a received communication signal, comprising a local oscillator for providing a reference signal at a local oscillator frequency; a mixer for mixing a received communication signal with a reference signal to provide the communication signal at an intermediate frequency; an analog-to-digital converter for converting the intermediate-frequency communication signal to a digital communication signal; a circuit for formatting the digital communication signal into in-phase (I) and quadrature-phase (Q) components; a sampling circuit for sampling the I components at twice a predetermined symbol rate to provide a first series of I-component samples at the predetermined symbol rate and a second series of I-component samples that are intermediate to the first series of I-component samples and at the predetermined symbol rate, and for sampling the Q components at twice the predetermined symbol rate to provide a first series of Q-component samples at the predetermined symbol rate and a second series of Q-component samples that are intermediate to the first series of Q-component samples and at the predetermined symbol rate; and a processor for processing the samples to estimate a phase-adjustment value and a symbol-timing-adjustment value; wherein the processor is coupled to the local oscillator for adjusting the phase of the reference signal in accordance with the phase-adjustment value and to the sampling circuit for adjusting the timing of said sampling in accordance with the symbol-timing-adjustment value.
Claim 2
Independent Claim
233 words
A system for acquiring carrier phase and symbol timing of a received communication signal, comprising a local oscillator for providing a reference signal at a local oscillator frequency; a mixer for mixing a received communication signal with a reference signal to provide the communication signal at an intermediate frequency; an analog-to-digital converter for converting the intermediate-frequency communication signal to a digital communication signal; a circuit for formatting the digital communication signal into in-phase (I) and quadrature-phase (Q) components; a sampling circuit for sampling the I components at twice a predetermined symbol rate to provide a first series of I-component samples at the predetermined symbol rate and a second series of I-component samples that are intermediate to the first series of I-component samples and at the predetermined symbol rate, and for sampling the Q components at twice the predetermined symbol rate to provide a first series of Q-component samples at the predetermined symbol rate and a second series of Q-component samples that are intermediate to the first series of Q-component samples and at the predetermined symbol rate; and a processor for processing the samples to estimate a phase-adjustment value and a symbol-timing-adjustment value; wherein the processor is coupled to the local oscillator for adjusting the phase of the reference signal in accordance with the phase-adjustment value and to the sampling circuit for adjusting the timing of said sampling in accordance with the symbol-timing-adjustment value.
Claim 3
Dependent Claim
24 words
A system according to claim 1, wherein the timing of said sampling is adjusted by a number of samples indicated by the symbol-timing-adjustment value.
Claim 4
Dependent Claim
118 words
A system according to claim 2, wherein the processor is adapted for estimating an amplitude component "y" of the symbol-timing-adjustment value by computing: y=(BB2-BB1)/(BB2+BB1), wherein ##EQU3## ##EQU4## B1(1)=W1.sub.1 +W1.sub.4 +W1.sub.7 +W1.sub.10 +. . . , B1(2)=W1.sub.2 +W1.sub.5 +W1.sub.8 +W1.sub.11 +. . . , B1(3)=W1.sub.3 +W1.sub.6 +W1.sub.9 +W1.sub.12 +. . . , B2(1)=W2.sub.1 +W2.sub.4 +W2.sub.7 +W2.sub.10 +. . . , B2(2)=W2.sub.2 +W2.sub.5 +W2.sub.8 +W2.sub.11 +. . . , B2(3)=W2.sub.3 +W2.sub.6 +W2.sub.9 +W2.sub.12 +. . . , W1 n is a complex sample consisting of a first-series I-component sample and a coincident first-series Q-component sample; and W2 n is a complex sample consisting of a second-series I-component sample and a coincident second-series Q-component sample, for n=1, 2,3, . . .
Claim 5
Dependent Claim
76 words
A system according to claim 3, wherein the processor is adapted for estimating a phase-adjustment value "φ A " by computing: φ.sub.A =(φ.sub.1 +φ.sub.2 +φ.sub.3)/6, wherein if BB1≧BB2, φ k is the phase angle Φ B of B1 (k) after removing the modulation for k=1, 2, 3, and otherwise, φ k is the phase angle Φ B of B2 (k) after removing the modulation for k=1, 2, 3; and wherein for B=a+jb, Φ.sub.B -tan.sup.-1 (a/b). 5.
Claim 6
Dependent Claim
45 words
A system according to claim 3, wherein the processor is adapted for estimating the sign of the symbol-timing-adjustment value by computing: ##EQU5## wherein, the sign is positive when CC1<CC2, and the sign is negative when CC1≧CC2, C1(k)=B1(k)+B2(k) for k=1, 2, 3, C2(1)=B1(1)+B2(3), C2(2)=B1(2)+B2(1), and C2(3)=B1(3)+B2(2).
Claim 7
Dependent Claim
75 words
A system according to claim 5, wherein the processor is adapted for estimating a phase-adjustment value "φ A " by computing: φ.sub.A =(φ.sub.1 +φ.sub.2 +φ.sub.3)/6, wherein if BB1≧BB2, φ k is the phase angle Φ B of B1 (k) after removing the modulation for k=1, 2, 3, and otherwise, φ k is the phase angle Φ B of B2 (k) after removing the modulation for k=1, 2, 3; and wherein for B=a+jb, Φ.sub.B=tan.sup.-1 (a/b). 7.
Claim 8
Dependent Claim
169 words
A system according to claim 1, wherein the processor is adapted for estimating a phase-adjustment value "φ A " by computing: φ.sub.A =(φ.sub.1 +φ.sub.2 +φ.sub.3)/6, wherein if BB1≧BB2, φ k is the phase angle Φ B of B1 (k) after removing the modulation for k=1, 2, 3, and otherwise, φ k is the phase angle Φ B of B2 (k) after removing the modulation for k=1, 2, 3; wherein for B=a+jb, Φ.sub.B =tan.sup.-1 (a/b); and wherein ##EQU6## ##EQU7## B1(1)=W1.sub.1 +W1.sub.4 +W1.sub.7 +W1.sub.10 +. . . , B1(2)=W1.sub.2 +W1.sub.5 +W1.sub.8 +W1.sub.11 +. . . , B1(3)=W1.sub.3 +W1.sub.6 +W1.sub.9 +W1.sub.12 +. . . , B2(1)=W2.sub.1 +W2.sub.4 +W2.sub.7 +W2.sub.10 +. . . , B2(2)=W2.sub.2 +W2.sub.5 +W2.sub.8 +W2.sub.11 +. . . , B2(3)=W2.sub.3 +W2.sub.6 +W2.sub.9 +W2.sub.12 +. . . , W1 n is a complex sample consisting of a first-series I-component sample and a coincident first-series Q-component sample; and W2 n is a complex sample consisting of a second-series I-component sample and a coincident second-series Q-component sample, for n=1, 2,3, . . .
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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) | 1999-08-06 | 2000-02-05 | 2000-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-08-06 | 2004-02-05 | 2004-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-08-06 | 2008-02-05 | 2008-08-06 | $7700.00 | Window Closed / Lapsed |