US5386202A
Expired / Lapsed
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Data communication modulation with managed intersymbol interference
Assignee: Conexant Systems Worldwide Inc
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Filing: 1993-11-03
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Granted: 1995-01-31
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Expires: 2013-11-03
Abstract
Abstract A communication system (10) includes a modulation section (12) and a demodulation section (14). The modulation section (12) performs frequency modulation in accordance with a frequency trajectory signal (28, 30, 32). An intersymbol interference (ISI) prediction filter (20) adjusts the amplitude of the frequency trajectory signal (28, 30, 32) in response to data code (16) sequences being conveyed over a plurality of symbols (18). More frequent data changes in the sequence of the data codes (16) lead to greater amplitudes in the frequency trajectory signal. The demodulation section (14) applies a distorted phase signal to a decision circuit (38). The distorted phase signal conveys a received phase (46) that includes ISI. Due to the equalization applied by the ISI prediction filter (20), the received phase (46) approximates a target phase (40, 42) in spite of the ISI.
Inventors
- 👤 Bruce A. Cochran
- 👤 Ronald D. McCallister
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:05
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/38; H04L25/40; H04L25/49; H04L25/497; H04L1/00; H04L1/20
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
87 words
A method for modulating data communications comprising the steps of: obtaining a first data code to be communicated during a first symbol and a second data code to be communicated during a second symbol; predicting intersymbol interference between said first and second symbols in response to said first and second data codes; generating a trajectory signal which is responsive to at least one of said first and second data codes and to said predicted intersymbol interference; and changing a carrier frequency in response to said trajectory signal.
Claim 2
Independent Claim
87 words
A method for modulating data communications comprising the steps of: obtaining a first data code to be communicated during a first symbol and a second data code to be communicated during a second symbol; predicting intersymbol interference between said first and second symbols in response to said first and second data codes; generating a trajectory signal which is responsive to at least one of said first and second data codes and to said predicted intersymbol interference; and changing a carrier frequency in response to said trajectory signal.
Claim 3
Dependent Claim
40 words
A method for modulating data communications as claimed in claim 1 wherein: said first and second data codes are obtained from a stream of data codes; and said predicting step comprises the step of filtering said stream of data codes.
Claim 4
Dependent Claim
35 words
A method for modulating data communications as claimed in claim 2 wherein: said filtering step generates a stream of ISI-adjusted data codes; and said generating step comprises the step of filtering said ISI-adjusted data codes.
Claim 5
Dependent Claim
57 words
A method for modulating data communications as claimed in claim 1 wherein: said first and second data codes are included in a stream of symbols, where each symbol conveys a single data code; and said generating step causes said trajectory signal during any one symbol to be responsive to said data codes for a plurality of symbols.
Claim 6
Dependent Claim
36 words
A method for modulating data communications as claimed in claim 4 wherein said generating step additionally comprises the step of filtering said first and second data codes through a filter that has an approximately Gaussian response.
Claim 7
Dependent Claim
66 words
A method for modulating data communications as claimed in claim 4 wherein: said generating step is responsible for a first portion of said intersymbol interference; said carrier frequency is detected at a receiver having a low pass filter which is responsible for a second portion of said intersymbol interference; and said predicting step predicts a combination of said first and second portions of said intersymbol interference.
Claim 8
Dependent Claim
51 words
A method for modulating data communications as claimed in claim 1 wherein: said trajectory signal exhibits a slope which changes over the course of said first symbol; and said generating step comprises the step of distributing said change in trajectory signal slope generally equally throughout the duration of said first symbol.
Claim 9
Dependent Claim
42 words
A method for modulating data communications as claimed in claim 1 wherein: said first and second data codes are obtained from a stream of data codes; and each of said data codes in said stream conveys more than one bit of data.
Claim 10
Dependent Claim
46 words
A method for modulating data communications as claimed in claim 1 wherein: said carrier frequency is detected at a receiver having a low pass filter which generates at least a portion of said intersymbol interference; and said predicting step predicts said portion of said intersymbol interference.
Claim 11
Dependent Claim
25 words
A method for modulating data communications as claimed in claim 1 additionally comprising the step of amplifying said carrier frequency with a non-linear power amplifier.
Claim 12
Independent Claim
164 words
A method for communicating data at a low bit error rate with high spectral efficiency, said method comprising the steps of: a) filtering a stream of data codes to generate a trajectory signal, each of said data codes being conveyed during a symbol; b) modulating a carrier frequency in response to said trajectory signal; c) translating said modulated carrier into a baseband signal; d) filtering said baseband signal to generate a distorted phase signal, said distorted phase signal exhibiting a phase during each of said symbols that is responsive to data conveyed during at least one other symbol; and e) estimating said stream of data codes in response to said distorted phase signal by employing a decision statistic which associates data codes with predetermined discrete phases; wherein said step a) is configured to shape said trajectory signal so that said distorted phase signal of said step d) exhibits a phase at a common point during each symbol that approximates one of said predetermined phases.
Claim 13
Independent Claim
164 words
A method for communicating data at a low bit error rate with high spectral efficiency, said method comprising the steps of: a) filtering a stream of data codes to generate a trajectory signal, each of said data codes being conveyed during a symbol; b) modulating a carrier frequency in response to said trajectory signal; c) translating said modulated carrier into a baseband signal; d) filtering said baseband signal to generate a distorted phase signal, said distorted phase signal exhibiting a phase during each of said symbols that is responsive to data conveyed during at least one other symbol; and e) estimating said stream of data codes in response to said distorted phase signal by employing a decision statistic which associates data codes with predetermined discrete phases; wherein said step a) is configured to shape said trajectory signal so that said distorted phase signal of said step d) exhibits a phase at a common point during each symbol that approximates one of said predetermined phases.
Claim 14
Dependent Claim
44 words
A method for communicating data as claimed in claim 11 wherein said step a) is further configured to shape said trajectory signal so that during each of said symbols said trajectory signal is responsive to data being conveyed during at least one other symbol.
Claim 15
Dependent Claim
61 words
A method for communicating data as claimed in claim 11 wherein: said step a) is further configured to shape said trajectory signal so that said trajectory signal exhibits an approximately Gaussian response to said data codes, and so that during each of said symbols said trajectory signal is responsive to a data code being conveyed during at least one other symbol.
Claim 16
Dependent Claim
49 words
A method for communicating data as claimed in claim 11 wherein: said trajectory signal shape exhibits a slope which changes over the course of each symbol; and said step a) comprises the step of distributing said change in trajectory signal slope generally equally throughout the duration of each symbol.
Claim 17
Dependent Claim
23 words
A method for communicating data as claimed in claim 11 wherein each of said data codes conveys more than one bit of data.
Claim 18
Dependent Claim
100 words
A method for communicating data as claimed in claim 11 wherein said trajectory signal shape exhibits a slope which changes over the course of each symbol, and said step a) comprises the steps of: filtering said stream of data codes to generate a stream of ISI-adjusted data codes; and filtering said stream of said ISI-adjusted data codes through a filter which causes said trajectory signal during each of said symbols to be responsive to data being conveyed during at least one other symbol, and which distributes said change in trajectory signal slope generally equally throughout the duration of each symbol.
Claim 19
Dependent Claim
24 words
A method for communicating data as claimed in claim 11 additionally comprising the step of amplifying said carrier frequency with a non-linear power amplifier.
Claim 20
Dependent Claim
109 words
A data communication modulator which manages intersymbol interference, comprising: means for obtaining a first data code to be communicated during a first symbol and a second data code to be communicated during a second symbol; a filter coupled to said obtaining means, said filter being configured to predict intersymbol interference between said first and second symbols in response to said first and second data codes and to generate a trajectory signal which is responsive to at least one of said first and second data codes and to said predicted intersymbol interference; and means, coupled to said filter means, for changing a carrier frequency in response to said trajectory signal.
Claim 21
Dependent Claim
109 words
A data communication modulator which manages intersymbol interference, comprising: means for obtaining a first data code to be communicated during a first symbol and a second data code to be communicated during a second symbol; a filter coupled to said obtaining means, said filter being configured to predict intersymbol interference between said first and second symbols in response to said first and second data codes and to generate a trajectory signal which is responsive to at least one of said first and second data codes and to said predicted intersymbol interference; and means, coupled to said filter means, for changing a carrier frequency in response to said trajectory signal.
Claim 22
Dependent Claim
57 words
A data communication modulator as claimed in claim 18 wherein: said first and second data codes are included in a stream of symbols, where each symbol conveys a single data code; and said filter is configured to cause said trajectory signal during any one symbol to be responsive to said data codes for a plurality of symbols.
Claim 23
Dependent Claim
62 words
A data communication modulator as claimed in claim 19 wherein: said filter introduces a first portion of said intersymbol interference; said carrier frequency is detected at a receiver having a low pass filter which introduces a second portion of said intersymbol interference; and said filter is further configured to predict a combination of said first and second portions of said intersymbol interference.
Claim 24
Dependent Claim
50 words
A data communication modulator as claimed in claim 18 wherein: said first and second data codes are obtained from a stream of data codes; and said obtaining and filtering means are each configured so that each of said data codes in said stream conveys more than one bit of data.
Claim 25
Dependent Claim
47 words
A data communication modulator as claimed in claim 18 wherein: said trajectory signal exhibits a slope which changes over the course of said first symbol; and said filter is configured to distribute said change in trajectory signal slope generally equally throughout the duration of said first symbol.
Claim 26
Dependent Claim
23 words
A data communication modulator as claimed in claim 18 additionally comprising a non-linear power amplifier having an input coupled to said changing 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) | 1998-01-30 | 1998-08-01 | 1999-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-30 | 2002-08-01 | 2003-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-30 | 2006-08-01 | 2007-01-31 | $7700.00 | Window Closed / Lapsed |