US4035625A
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Method and apparatus for performing binary equalization in voice-band phase-modulation modems
Assignee: Racal Data Communications Inc
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Filing: 1975-07-31
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Granted: 1977-07-12
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Expires: 1995-07-31
Abstract
Abstract A phase modulation modem providing switch selectable speeds on voice-band channels utilizes four phase, modified eight phase, and optimized eight phase, two amplitude modulation techniques. A binary equalizer automatically corrects for envelope delay and amplitude distortion of the carrier signal caused by the voice-band channel. Each symbol time, the X-axis error and Y-axis error for the received symbol is determined by comparing the received X and Y components with stored ideal X and Y components for that symbol. These error X and error Y values are used to modify primary and secondary equalization constants. The equalization constants, thus modified during this symbol time, are used on the next received symbol to correct for the phase and amplitude distortion measured during past symbol times. This sequence is repeated for each symbol time. Preselected equalization constants are utilized on the first symbol received. To equalize the line very rapidly at start-up, a phase training signal is sent prior to data transmission. After this "course" adjustment the equalizer operates on the received data symbols to very accurately correct the phase and amplitude distortions of the received symbols. A symbol quality signal is conveniently generated as a result of the equalizer operation.
Inventors
- 👤 Ran-Fun Chiu
- 👤 James Bryon Sherman
- 👤 Judson Truman Gilbert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:47
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03012; H04L25/03019; H04L25/03038; H04L27/00; H04L27/18; H04L27/22
Claims Analysis
Total Claims: 41
Claim 1
Independent Claim
95 words
A method for correcting the envelope delay and amplitude distortion characteristic of voice-band transmission channels on signals propagated therethrough, comprising: converting a received symbol into its corresponding binary X and binary Y components; equalizing the binary X and binary Y components of the received symbol according to previously defined equalization constants; generating the difference between the equalized components of said received symbol and the ideal binary X and binary Y components of said symbol; and utilizing said difference and the binary X and binary Y components of the received symbol to modify the equalization constants.
Claim 2
Independent Claim
95 words
A method for correcting the envelope delay and amplitude distortion characteristic of voice-band transmission channels on signals propagated therethrough, comprising: converting a received symbol into its corresponding binary X and binary Y components; equalizing the binary X and binary Y components of the received symbol according to previously defined equalization constants; generating the difference between the equalized components of said received symbol and the ideal binary X and binary Y components of said symbol; and utilizing said difference and the binary X and binary Y components of the received symbol to modify the equalization constants.
Claim 3
Dependent Claim
84 words
The method of claim 1 wherein said generating step includes: locating the area of the phase plane in which the received symbol belongs by use of the equalized binary X and binary Y components; generating the ideal binary X and ideal binary Y component in the area of the phase plane occupied by the received symbol; and subtracting the ideal X component and ideal Y component from the equalized X component and Y component, respectively, to obtain an error X and error Y value.
Claim 4
Dependent Claim
74 words
The method of claim 1 wherein said utilizing step includes: generating a change of correction factor by using said difference and the binary X and binary Y components of said received symbol; generating a new correction constant by use of the newly generated change of correction factor; generating a change of equalization factor by use of the new correction constant; and modifying the equalization constants according to the newly generated change of equalization factor.
Claim 5
Dependent Claim
61 words
The method of claim 1 further comprising: generating the ideal phase angle of the received symbol in response to the equalized binary X and binary Y components of the received symbol; subtracting said generated ideal phase angle from the ideal phase angle generated for the previously received symbol to get a phase change; and converting the phase change to digital data.
Claim 6
Independent Claim
138 words
A method for correcting for the phase and amplitude distortion characteristic of voice-band transmission channels on double-sideband modulated carrier signals, comprising: converting a received symbol into its corresponding binary X and binary Y components; storing the binary X and binary Y components of the received symbol with a plurality of binary X and binary Y components of previously received symbols; equalizing the stored binary X and binary Y components of a symbol according to previously calculated equalization constants; generating an error X and error Y factor by taking the difference between the equalized binary X and binary Y components and the respective ideal binary X and binary Y components of the symbols, and; calculating new equalization constants based upon the generated error X and error Y factor and the binary X and binary Y components of received symbols.
Claim 7
Independent Claim
138 words
A method for correcting for the phase and amplitude distortion characteristic of voice-band transmission channels on double-sideband modulated carrier signals, comprising: converting a received symbol into its corresponding binary X and binary Y components; storing the binary X and binary Y components of the received symbol with a plurality of binary X and binary Y components of previously received symbols; equalizing the stored binary X and binary Y components of a symbol according to previously calculated equalization constants; generating an error X and error Y factor by taking the difference between the equalized binary X and binary Y components and the respective ideal binary X and binary Y components of the symbols, and; calculating new equalization constants based upon the generated error X and error Y factor and the binary X and binary Y components of received symbols.
Claim 8
Dependent Claim
72 words
The method of claim 5 wherein said generating step includes: normalizing the equalized binary X and binary Y components to a magnitude and sign indication; locating the area of the phase plane in which the received symbol belongs by use of the normalized binary X and binary Y components; and generating the X component and Y component of the ideal point in the area of the phase plane occupied by the symbol.
Claim 9
Dependent Claim
35 words
The method of claim 6 wherein said locating step, comprises: addressing a memory with the magnitude indication of the binary X and binary Y components of the symbol to retrieve a first quadrant area indication.
Claim 10
Dependent Claim
56 words
The method of claim 7 wherein said X and Y component generating step, comprises: addressing a memory with the first quadrant area indication and binary X and binary Y component sign indications to retrieve the X component and Y component of the ideal point in the area of the phase plane occupied by the received symbol.
Claim 11
Dependent Claim
55 words
The method of claim 6 further comprising: generating the phase angle of the ideal point in the area of the phase plane occupied by the received symbol; subtracting said generated phase angle from the phase angle generated for the previous received symbol to get a phase difference; and converting the phase difference to digital data.
Claim 12
Dependent Claim
36 words
The method of claim 9 wherein said locating step, comprises: addressing a first memory with the magnitude of the normalized binary X and binary Y components of the symbol to retrieve a first quadrant area indication.
Claim 13
Dependent Claim
58 words
The method of claim 10 wherein said generating the X component and Y component step, comprises: addressing a second memory with the first quadrant area indication and binary X and binary Y component sign indication to retrieve the X component and Y component of the ideal point in the area of the phase plane occupied by the symbol.
Claim 14
Dependent Claim
44 words
The method of claim 11 wherein said generating the phase angle of ideal point step, comprises: addressing said second memory with the first quadrant area indication and binary X and binary Y component sign indication to retrieve the phase angle of the ideal point.
Claim 15
Independent Claim
201 words
A method for correcting the delay and amplitude distortion created in double-sideband modulated signals propagated in voice-band transmission channels, comprising: converting a received symbol into its corresponding binary X and binary Y components; storing the binary X and binary Y components of the received symbol; prior to reception of the next symbol, calculating equalization constants based on N, (N being any positive integer equal or greater than 1) previously received binary X and binary Y symbol components and a previously calculated error X and error Y factor; prior to reception of the next symbol, equalizing a stored binary X and binary Y set of components of a received symbol according to the calculated equalization constants; prior to reception of the next symbol, comparing the equalized binary X and binary Y components of the symbol with its respective ideal binary X and binary Y components; prior to reception of the next symbol, calculating an error X and error Y factor by taking the difference between the equalized binary X and binary Y components and the ideal binary X and binary Y components of the symbol; and storing the calculated error X and error Y factors for use in calculating new equalization constants.
Claim 16
Independent Claim
201 words
A method for correcting the delay and amplitude distortion created in double-sideband modulated signals propagated in voice-band transmission channels, comprising: converting a received symbol into its corresponding binary X and binary Y components; storing the binary X and binary Y components of the received symbol; prior to reception of the next symbol, calculating equalization constants based on N, (N being any positive integer equal or greater than 1) previously received binary X and binary Y symbol components and a previously calculated error X and error Y factor; prior to reception of the next symbol, equalizing a stored binary X and binary Y set of components of a received symbol according to the calculated equalization constants; prior to reception of the next symbol, comparing the equalized binary X and binary Y components of the symbol with its respective ideal binary X and binary Y components; prior to reception of the next symbol, calculating an error X and error Y factor by taking the difference between the equalized binary X and binary Y components and the ideal binary X and binary Y components of the symbol; and storing the calculated error X and error Y factors for use in calculating new equalization constants.
Claim 17
Dependent Claim
80 words
The method of claim 13 wherein said comparing step, includes: normalizing the equalized binary X and binary Y components to a magnitude and sign indication; locating the area of the phase plane in which the received symbol belongs by use of the normalized binary X and binary Y components; and generating the X component and Y component of the ideal point in the area of the phase plane occupied by the symbol in response to the located phase plane area.
Claim 18
Dependent Claim
116 words
In a double-sideband modulated carrier system for use with communication channels, said system having means for converting a received analog symbol into corresponding binary X and binary Y components, apparatus for correcting for the phase and amplitude distortion characteristic of said communication channels, comprising: means for equalizing the binary X and binary Y components of the received symbols according to previously generated equalization constants; means for generating the difference between the equalized components of said received symbol and the ideal binary X and binary Y components of said symbol; and means utilizing the signals from the difference generating means and the binary X and binary Y components of the received symbol for generating modified equalization constants.
Claim 19
Dependent Claim
116 words
In a double-sideband modulated carrier system for use with communication channels, said system having means for converting a received analog symbol into corresponding binary X and binary Y components, apparatus for correcting for the phase and amplitude distortion characteristic of said communication channels, comprising: means for equalizing the binary X and binary Y components of the received symbols according to previously generated equalization constants; means for generating the difference between the equalized components of said received symbol and the ideal binary X and binary Y components of said symbol; and means utilizing the signals from the difference generating means and the binary X and binary Y components of the received symbol for generating modified equalization constants.
Claim 20
Dependent Claim
94 words
The apparatus of claim 15 wherein said difference generating means, comprises: means for locating the area of the phase plane in which the received symbol belongs by use of the equalized binary X and binary Y components; means for generating the X component and Y component of the ideal point in the area of the phase plane occupied by the received symbol; and means for subtracting the X component and Y component of the ideal point from the equalized X component and Y component, respectively, to obtain an error X and error Y value.
Claim 21
Dependent Claim
87 words
The apparatus of claim 15 wherein said modified equalization constant generating means, comprises: means for generating a change of correction factor by using the output from said difference generating means and the unequalized binary X and binary Y components of said received symbol; means for generating a new correction constant by use of the change of correction factor; means for generating a change of equalization factor by use of the new correction constant; and means for modifying the equalization constant according to the change of equalization factor.
Claim 22
Dependent Claim
64 words
The apparatus of claim 16 further comprising: means for generating the phase angle of the received symbol in response to the equalized binary X and binary Y components of the received symbol; means for subtracting the generated phase angle from the phase angle generated for the previously received symbol to get a phase change; and means for converting the phase change to digital data.
Claim 23
Dependent Claim
220 words
In a double-sideband modulated carrier system for use with voice-band communication channels, said system having means for converting a received analog symbol into corresponding binary X and binary Y components, apparatus for correcting for the phase and amplitude distortion characteristic of said communication channels, comprising: means for storing the binary X and binary Y components of the received symbol; means for calculating equalization constants based on N (N being any positive non-zero integer) previously received binary X and binary Y symbol components and a previously calculated error X and error Y factor, prior to reception of the next symbol; means for equalizing the binary X and binary Y components of a received symbol according to the calculated equalization constants, prior to reception of the next symbol; means for comparing the equalized binary X and binary Y component of the symbol with its respective ideal binary X and binary Y components, prior to reception of the next symbol; means for calculating an error X and error Y factor from the difference between the equalized binary X and binary Y components and the ideal binary X and binary Y components, prior to reception of the next symbol; and means for storing the calculated error X and error Y factor for use in calculating new equalization constants upon reception of the next symbol.
Claim 24
Dependent Claim
220 words
In a double-sideband modulated carrier system for use with voice-band communication channels, said system having means for converting a received analog symbol into corresponding binary X and binary Y components, apparatus for correcting for the phase and amplitude distortion characteristic of said communication channels, comprising: means for storing the binary X and binary Y components of the received symbol; means for calculating equalization constants based on N (N being any positive non-zero integer) previously received binary X and binary Y symbol components and a previously calculated error X and error Y factor, prior to reception of the next symbol; means for equalizing the binary X and binary Y components of a received symbol according to the calculated equalization constants, prior to reception of the next symbol; means for comparing the equalized binary X and binary Y component of the symbol with its respective ideal binary X and binary Y components, prior to reception of the next symbol; means for calculating an error X and error Y factor from the difference between the equalized binary X and binary Y components and the ideal binary X and binary Y components, prior to reception of the next symbol; and means for storing the calculated error X and error Y factor for use in calculating new equalization constants upon reception of the next symbol.
Claim 25
Dependent Claim
85 words
The apparatus of claim 19 wherein said comparing means, comprises: means for normalizing the equalized binary X and binary Y components to separate magnitude and sign indications; means for identifying the area of the phase plane in which the received symbol belongs by use of the normalized binary X and binary Y components; and means for generating the X component and Y component of the ideal point in the area of the phase plane occupied by the symbol in response to the identified phase plane.
Claim 26
Dependent Claim
41 words
The apparatus of claim 20 wherein said identifying means, comprises: a memory means addressable by the magnitude of the binary X and binary Y components, said memory means containing first quadrant phase plane area indications in which the symbol could belong.
Claim 27
Dependent Claim
57 words
The apparatus of claim 21 wherein said generating means, comprises: a memory means addressable by the first quadrant phase plane area indication and the binary X and binary Y component sign indications, said memory means containing the X component and Y component of the ideal point in the area of the phase plane occupied by the symbol.
Claim 28
Dependent Claim
81 words
The apparatus of claim 20, further comprising: means for generating the phase angle of the ideal point in the area of the phase plane occupied by the symbol, in response to the identified phase plane area of the received symbol; means for storing the generated phase angle; means for subtracting the generated phase angle from the phase angle generated for a previous received symbol in said storing means; and means for converting the difference from said subtracting means to digital data.
Claim 29
Dependent Claim
42 words
The apparatus of claim 23 wherein said identifying means, comprises: a memory means addressable by the magnitude of the binary X and binary Y components, said memory means containing first quadrant phase plane area indications in which the received symbol could belong.
Claim 30
Dependent Claim
58 words
The apparatus of claim 24 wherein said generating means, comprises: a memory means addressable by the first quadrant phase plane area indication and the binary X and binary Y component sign indications, said memory means containing the X component and Y component of the ideal point in the area of the phase plane occupied by the received symbol.
Claim 31
Dependent Claim
106 words
In a double-sideband modulated carrier system for use with voice-band-communication channels, said system having means for converting a received analog symbol into corresponding binary X and binary Y components, apparatus for compensating for phase and amplitude distortion in said channel said apparatus including: means for equalizing the binary X and binary Y components; first memory means responsive to the equalized binary X and binary Y components of the received symbols for generating an address indication; and second memory means responsive to the address indication from said first memory means for generating data represented by the equalized X and Y symbol components addressing said first memory means.
Claim 32
Dependent Claim
106 words
In a double-sideband modulated carrier system for use with voice-band-communication channels, said system having means for converting a received analog symbol into corresponding binary X and binary Y components, apparatus for compensating for phase and amplitude distortion in said channel said apparatus including: means for equalizing the binary X and binary Y components; first memory means responsive to the equalized binary X and binary Y components of the received symbols for generating an address indication; and second memory means responsive to the address indication from said first memory means for generating data represented by the equalized X and Y symbol components addressing said first memory means.
Claim 33
Dependent Claim
122 words
In a modulated carrier system for use with a communication channel, said system having means for converting a received analog symbol into corresponding binary X and binary Y components, said channel exhibiting a phase and amplitude distortion characteristic apparatus for compensating for the phase and amplitude distortion in said channel said apparatus including: means for equalizing the binary X and binary Y components; first memory means responsive to the equalized binary X and binary Y components of the received symbols for generating an address indication; and second memory means responsive to the address indication from said first memory means for generating ideal binary X and binary Y symbols represented by the equalized X and Y symbol components addressing said first memory means.
Claim 34
Dependent Claim
122 words
In a modulated carrier system for use with a communication channel, said system having means for converting a received analog symbol into corresponding binary X and binary Y components, said channel exhibiting a phase and amplitude distortion characteristic apparatus for compensating for the phase and amplitude distortion in said channel said apparatus including: means for equalizing the binary X and binary Y components; first memory means responsive to the equalized binary X and binary Y components of the received symbols for generating an address indication; and second memory means responsive to the address indication from said first memory means for generating ideal binary X and binary Y symbols represented by the equalized X and Y symbol components addressing said first memory means.
Claim 35
Dependent Claim
72 words
The apparatus of claim 27 wherein said apparatus for compensating further includes: means for equalizing the binary X and binary Y components of the received symbols according to previously defined equalization constants; means for generating the difference between the equalized components of said received symbol and the ideal binary X and binary Y components of said symbol; and means utilizing the signals from the difference generating means for generating modified equalization constants.
Claim 36
Dependent Claim
83 words
The apparatus of claim 28 wherein said modified equalization constant generating means, comprises: means for generating a change of correction factor by using the output from said difference generating means and the unequalized binary X and binary Y components; means for generating a new correction constant by use of the change of correction factor; means for generating a change of equalization factor by use of the new correction constant; and means for modifying the equalization constant according to the change of equalization factor.
Claim 37
Dependent Claim
125 words
In a modulated carrier system for use with a communication channel, said system having means for converting a received analog symbol into corresponding binary X and binary Y components, a method for correcting for the phase and amplitude distortion characteristic of said channel, comprising: equalizing the binary X and binary Y components of the received symbol according to previously defined equalization constants; generating the difference between the equalized components of said received symbol and the ideal binary X and binary Y components of said symbol; and modifying the equalization constants by utilizing the difference between the equalized binary X and binary Y components and their respective ideal binary X and binary Y components, and the binary X and binary Y components of the received symbol.
Claim 38
Dependent Claim
125 words
In a modulated carrier system for use with a communication channel, said system having means for converting a received analog symbol into corresponding binary X and binary Y components, a method for correcting for the phase and amplitude distortion characteristic of said channel, comprising: equalizing the binary X and binary Y components of the received symbol according to previously defined equalization constants; generating the difference between the equalized components of said received symbol and the ideal binary X and binary Y components of said symbol; and modifying the equalization constants by utilizing the difference between the equalized binary X and binary Y components and their respective ideal binary X and binary Y components, and the binary X and binary Y components of the received symbol.
Claim 39
Dependent Claim
84 words
The method of claim 30 wherein said generating step includes: locating the area of the phase plane in which the received symbol belongs by use of the equalized binary X and binary Y components; generating the ideal binary X and ideal binary Y component in the area of the phase plane occupied by the received symbol; and subtracting the ideal X component and ideal Y component from the equalized X component and Y component, respectively, to obtain an error X and error Y value.
Claim 40
Dependent Claim
98 words
The method of claim 30 wherein said modifying step includes: generating a change of correction of factor for the X and Y components, respectively, by using the difference between the corrected binary X and binary Y components and the ideal binary X and binary Y components, and the received unequalized binary X and binary Y components; generating a new correction constant by use of the newly generated change of correction factor; generating a change of equalization factor by use of the new correction constant; and modifying the equalization constants according to the newly generated change of equalization factor.
Claim 41
Dependent Claim
60 words
The method of claim 30 further comprising: generating the ideal phase angle of the received symbol in response to the equalized binary X and binary Y components of the received symbol; subtracting the generated phase angle from the ideal phase angle generated for the previously received symbol to get a phase change; and converting the phase change to digital data.
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) | 1980-07-11 | 1981-01-10 | 1981-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-11 | 1985-01-10 | 1985-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-11 | 1989-01-10 | 1989-07-12 | $7700.00 | Window Closed / Lapsed |