US5233632A
Expired / Lapsed
US
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Communication system receiver apparatus and method for fast carrier acquisition
Assignee: Motorola Solutions Inc
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Filing: 1991-05-10
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Granted: 1993-08-03
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Expires: 2011-05-10
Abstract
Abstract A communications system receiver (100) is disclosed which receives a transmitted signal over a radio channel. The transmitted signal includes data and a predetermined synchronization sequence. The receiver (100) includes a demodulator (215), and a stored replica (207) of the predetermined synchronization sequence. The receiver (100) further includes apparatus (102) for computing (308) a reconstructed signal, by using the channel impulse response characteristic and the stored replica (207) of the synchronization sequence. A feature of the invention is to estimate (310) a phase offset value between an incoming signal and the reconstructed signal, for a plurality of synchronization symbols. This serves to establish (315) a relationship between the phase offset and a synchronization symbol index. The receiver then employs this relationship to derive (317) at least one "previous" phase state (214) for initializing (314) the demodulator (215).
Inventors
- 👤 Kevin L. Baum
- 👤 David E. Borth
- 👤 Phillip D. Rasky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:49
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/06; H04B1/16; H04B1/30
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
146 words
A communications system receiver for receiving a transmitted signal over a channel having an impulse response characteristic, the transmitted signal including data and a predetermined synchronization sequence having a plurality of synchronization symbols, the receiver storing a replica of the predetermined synchronization sequence for comparison to a received synchronization sequence, the communications system receiver comprising: means for computing a reconstructed signal using the impulse response characteristic and the replica of the synchronization sequence; means for computing a plurality of phase difference values between an incoming signal and said reconstructed signal for the plurality of synchronization symbols; means for performing a curve-fit of said plurality of phase difference values versus a synchronization symbol index for the plurality of synchronization symbols, whereby a best-fit line is produced; and means for extrapolating from said best-fit line at least one phase state which corresponds to a previous synchronization symbol index.
Claim 2
Dependent Claim
146 words
A communications system receiver for receiving a transmitted signal over a channel having an impulse response characteristic, the transmitted signal including data and a predetermined synchronization sequence having a plurality of synchronization symbols, the receiver storing a replica of the predetermined synchronization sequence for comparison to a received synchronization sequence, the communications system receiver comprising: means for computing a reconstructed signal using the impulse response characteristic and the replica of the synchronization sequence; means for computing a plurality of phase difference values between an incoming signal and said reconstructed signal for the plurality of synchronization symbols; means for performing a curve-fit of said plurality of phase difference values versus a synchronization symbol index for the plurality of synchronization symbols, whereby a best-fit line is produced; and means for extrapolating from said best-fit line at least one phase state which corresponds to a previous synchronization symbol index.
Claim 3
Dependent Claim
23 words
A communications system receiver in accordance with claim 1, further comprising a demodulator which is initialized with said at least one phase state.
Claim 4
Dependent Claim
118 words
A communications system receiver for receiving a transmitted signal over a channel having an impulse response characteristic, the transmitted signal including data and a predetermined synchronization sequence having a plurality of synchronization symbols, the receiver having a demodulator and storing a replica of the predetermined synchronization sequence for comparison to a received synchronization sequence, the communications system receiver comprising: means for computing a reconstructed signal using the impulse response characteristic and the replica of the synchronization sequence; means, coupled to said means for computing, for estimating a phase offset value corresponding to at least one of a plurality of synchronization symbol indices; and means for initializing the demodulator with at least one of said estimated phase offset values.
Claim 5
Dependent Claim
118 words
A communications system receiver for receiving a transmitted signal over a channel having an impulse response characteristic, the transmitted signal including data and a predetermined synchronization sequence having a plurality of synchronization symbols, the receiver having a demodulator and storing a replica of the predetermined synchronization sequence for comparison to a received synchronization sequence, the communications system receiver comprising: means for computing a reconstructed signal using the impulse response characteristic and the replica of the synchronization sequence; means, coupled to said means for computing, for estimating a phase offset value corresponding to at least one of a plurality of synchronization symbol indices; and means for initializing the demodulator with at least one of said estimated phase offset values.
Claim 6
Dependent Claim
88 words
A communications system receiver in accordance with claim 3, wherein said means for estimating further comprises: means for computing a plurality of phase difference values between an incoming signal and said reconstructed signal for the plurality of synchronization symbols; means for performing a curve-fit of said plurality of phase difference values versus said synchronization symbol indices, whereby a best-fit line is produced; and means for extrapolating from said best-fit line at least a first and a second phase state which each correspond to a previous synchronization symbol index.
Claim 7
Dependent Claim
25 words
A communications system receiver in accordance with claim 3, further comprising means, coupled to the demodulator, for removing inter-symbol interference (ISI) within said incoming signal.
Claim 8
Dependent Claim
19 words
A communications system receiver in accordance with claim 5, wherein said means for removing ISI further comprises an equalizer.
Claim 9
Dependent Claim
169 words
A communications system receiver for receiving a transmitted signal over a channel having an impulse response characteristic, the transmitted signal including data and a predetermined synchronization sequence having a plurality of synchronization symbols, the receiver having a demodulator and storing a replica of the predetermined synchronization sequence for comparison to a received synchronization sequence, the communications system receiver comprising: means for computing a reconstructed signal using the impulse response characteristic and the replica of the synchronization sequence; means for computing a plurality of phase difference values between an incoming signal and said reconstructed signal for the plurality of synchronization symbols; means for performing a curve-fit of said plurality of phase difference values versus a synchronization symbol index for the plurality of synchronization symbols, whereby a best-fit line is produced; means for extrapolating from said best-fit line at least a first and a second phase state which each correspond to a previous synchronization symbol index; and means for initializing the demodulator with at least said first and second phase state.
Claim 10
Dependent Claim
169 words
A communications system receiver for receiving a transmitted signal over a channel having an impulse response characteristic, the transmitted signal including data and a predetermined synchronization sequence having a plurality of synchronization symbols, the receiver having a demodulator and storing a replica of the predetermined synchronization sequence for comparison to a received synchronization sequence, the communications system receiver comprising: means for computing a reconstructed signal using the impulse response characteristic and the replica of the synchronization sequence; means for computing a plurality of phase difference values between an incoming signal and said reconstructed signal for the plurality of synchronization symbols; means for performing a curve-fit of said plurality of phase difference values versus a synchronization symbol index for the plurality of synchronization symbols, whereby a best-fit line is produced; means for extrapolating from said best-fit line at least a first and a second phase state which each correspond to a previous synchronization symbol index; and means for initializing the demodulator with at least said first and second phase state.
Claim 11
Dependent Claim
23 words
A communications system receiver in accordance with claim 7, further comprising an equalizer means for removing inter-symbol interference (ISI) within said incoming signal.
Claim 12
Independent Claim
158 words
A method of acquiring carrier signal frequency and phase in a communications system receiver, the carrier signal transporting a signal over a channel having an impulse response characteristic, the signal including data and a predetermined synchronization sequence having a plurality of synchronization symbols, the receiver having a demodulator and storing a replica of the predetermined synchronization sequence for comparison to a received synchronization sequence, the method comprising the steps of: computing a reconstructed signal using the impulse response characteristic and the replica of the synchronization sequence; estimating a phase offset value for the plurality of synchronization symbols, such that a relationship is established between the phase offset value and a synchronization symbol index, wherein the step of estimating comprises the step of computing a plurality of phase difference values between an incoming signal and said reconstructed signal for the plurality of synchronization symbols; and initializing the demodulator with at least one phase offset value derived from said relationship.
Claim 13
Independent Claim
158 words
A method of acquiring carrier signal frequency and phase in a communications system receiver, the carrier signal transporting a signal over a channel having an impulse response characteristic, the signal including data and a predetermined synchronization sequence having a plurality of synchronization symbols, the receiver having a demodulator and storing a replica of the predetermined synchronization sequence for comparison to a received synchronization sequence, the method comprising the steps of: computing a reconstructed signal using the impulse response characteristic and the replica of the synchronization sequence; estimating a phase offset value for the plurality of synchronization symbols, such that a relationship is established between the phase offset value and a synchronization symbol index, wherein the step of estimating comprises the step of computing a plurality of phase difference values between an incoming signal and said reconstructed signal for the plurality of synchronization symbols; and initializing the demodulator with at least one phase offset value derived from said relationship.
Claim 14
Dependent Claim
72 words
A method of acquiring carrier signal frequency and phase in accordance with claim 9, wherein said step of estimating further comprises: performing a curve-fit of said plurality of phase difference values versus the synchronization symbol index for the plurality of synchronization symbols, whereby a best-fit line is produced; and extrapolating from said best-fit line at least a first and a second phase state which each correspond to a previous synchronization symbol index.
Claim 15
Dependent Claim
29 words
A method of acquiring carrier signal frequency and phase in accordance with claim 10, wherein said step of performing a curve fit further comprises performing a least-squares polynomial curve-fit.
Claim 16
Dependent Claim
28 words
A method of acquiring carrier signal frequency and phase in accordance with claim 10, wherein said step of performing a curve-fit further comprises performing a weighted least-squares curve-fit.
Claim 17
Dependent Claim
41 words
A method of acquiring carrier signal frequency and phase in accordance with claim 12, further comprising calculating a weighting coefficient for each of said phase difference values, said weighting coefficient being based on a signal-to-noise ratio variance among phase difference samples.
Claim 18
Independent Claim
168 words
A method of acquiring carrier signal frequency and phase in a communications system receiver, the carrier signal transporting a signal over a channel having an impulse response characteristic, the signal including data and a predetermined synchronization sequence having a plurality of synchronization symbols, the receiver having a demodulator and storing a replica of the predetermined synchronization sequence for comparison to a received synchronization sequence, the method comprising the steps of: computing a reconstructed signal using the impulse response characteristic and the replica of the synchronization sequence; computing a plurality of phase difference values between an incoming signal and said reconstructed signal for the plurality of synchronization symbols; performing a polynomial curve-fit of said plurality of phase difference values versus a synchronization symbol index for the plurality of synchronization symbols, whereby a best-fit line is produced; extrapolating from said best-fit line at least a first and a second phase state which each correspond to a previous synchronization symbol; and initializing the demodulator with said first and second phase states.
Claim 19
Independent Claim
168 words
A method of acquiring carrier signal frequency and phase in a communications system receiver, the carrier signal transporting a signal over a channel having an impulse response characteristic, the signal including data and a predetermined synchronization sequence having a plurality of synchronization symbols, the receiver having a demodulator and storing a replica of the predetermined synchronization sequence for comparison to a received synchronization sequence, the method comprising the steps of: computing a reconstructed signal using the impulse response characteristic and the replica of the synchronization sequence; computing a plurality of phase difference values between an incoming signal and said reconstructed signal for the plurality of synchronization symbols; performing a polynomial curve-fit of said plurality of phase difference values versus a synchronization symbol index for the plurality of synchronization symbols, whereby a best-fit line is produced; extrapolating from said best-fit line at least a first and a second phase state which each correspond to a previous synchronization symbol; and initializing the demodulator with said first and second phase states.
Claim 20
Dependent Claim
28 words
A method of acquiring carrier signal frequency and phase in accordance with claim 14, wherein said step of performing a curve-fit further comprises performing a weighted least-squares curve-fit.
References Cited (Backward Citations)
US4527491A
Cited
US5012491A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-02 | 1997-02-01 | 1997-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-02 | 2001-02-01 | 2001-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-02 | 2005-02-01 | 2005-08-03 | $7700.00 | Window Closed / Lapsed |