US3757221A
Expired / Lapsed
US
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Automatic equalizer system for phase modulated data signals
Assignee: Siemens AG
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Filing: 1971-06-02
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Granted: 1973-09-04
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Expires: 1991-06-02
Abstract
Abstract An automatic equalizer system for phase-modulated data signals, which is provided on the receiving side of a band-limited transmission channel and is connected with a receiver via a demodulator, comprises an equalizer which has N filter members with N respective outputs. N-1 outputs are connected with the inputs of a computer and all N outputs are connected via N variable circuit elements with the inputs of an adder; THE OUTPUT OF THE TRANSMISSION CHANNEL IS CONNECTED WITH THE COMPUTER ON THE ONE HAND VIA A SYNC RECOVERY CIRCUIT AND ON THE OTHER HAND, VIA A REFERENCE CLOCK PROVIDED WITH A SYNCHRONIZATION DEVICE. N-1 outputs of the computer are associated with those N-1 variable elements whose inputs lead simultaneously to the inputs of the computer, in such a manner as to effect an adaptive adjustment of the variable circuit elements. The output of the equalizer is connected via automatic gain control means with that variable element of the equalizer which is associated with the filter member whose output does not lead to the computer.
Inventors
- 👤 K Moehrmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:52
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/01
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
259 words
An automatic equalizer system for phase-modulated data signals with random properties, which is provided on the receiving side of a band-limited transmission channel and connected to a receiver via a demodulator, said system comprising an equalizer, the equalizer having input means which are the input means of the fliter members and an output and having the structure of a filter bank formed of N filter members with input means and N respective outputs; a computer comprising means for influencing the equalizer to minimize the distortions in the phase-modulated data signals at the time points of the normal zero crossings of the equalized phase-modulated data signal at the center of the modulation intervals, N-1 of said filter outputs being connected to the inputs to said computer; N variable circuit elements and an adder having inputs and outputs, all of said N filter outputs being connected via said respective N variable elements to the inputs of said adder; a sync recovery circuit, a reference clock with synchronizing means, the output of the transmission channel being connected to said computer on the one hand via said sync recovery circuit and on the other hand vai said reference clock, N-1 outputs of said computer being associated with those N-1 variable elements whose inputs simultaneously lead to the inputs of said computer whereby said variable elements are adaptively adjusted; and automatic gain control means connecting the out-put of said equalizer to that variable element of the equalizer which is associated with the one remaining filter member whose output is not connected to said computer.
Claim 2
Dependent Claim
259 words
An automatic equalizer system for phase-modulated data signals with random properties, which is provided on the receiving side of a band-limited transmission channel and connected to a receiver via a demodulator, said system comprising an equalizer, the equalizer having input means which are the input means of the fliter members and an output and having the structure of a filter bank formed of N filter members with input means and N respective outputs; a computer comprising means for influencing the equalizer to minimize the distortions in the phase-modulated data signals at the time points of the normal zero crossings of the equalized phase-modulated data signal at the center of the modulation intervals, N-1 of said filter outputs being connected to the inputs to said computer; N variable circuit elements and an adder having inputs and outputs, all of said N filter outputs being connected via said respective N variable elements to the inputs of said adder; a sync recovery circuit, a reference clock with synchronizing means, the output of the transmission channel being connected to said computer on the one hand via said sync recovery circuit and on the other hand vai said reference clock, N-1 outputs of said computer being associated with those N-1 variable elements whose inputs simultaneously lead to the inputs of said computer whereby said variable elements are adaptively adjusted; and automatic gain control means connecting the out-put of said equalizer to that variable element of the equalizer which is associated with the one remaining filter member whose output is not connected to said computer.
Claim 3
Dependent Claim
26 words
In an equalizer system according to claim 1, said filter bank being formed of a filter chain network having taps which constitute said respective filter outputs.
Claim 4
Dependent Claim
64 words
In an equalizer system according to claim 2, the filter members contained in said filter chain being formed of delay elements; the input of said filter chain being connected, on the one hand, directly with said computer and on the other hand via an additional variable member with said adder contained in the equalizer; said additional variable element being under control by said computer.
Claim 5
Dependent Claim
126 words
In an equalizer system according to claim 1, said filter bank containing a chain of delay elements, each of which has a delay T equal to the duration of one modulation interval; a further filter (F( omega ); 445) connected with each tap and with the input and the output of the chain of delay elements; the taps of the chain of delay elements, the input and output of the chain and also the outputs of said further filters (F( omega ); 445) being connected via variable elements (43, 30 to 33, 443, 430 to 433) with the inputs (35 to 39, 501, 401, 435 to 439) of said adder (40); and said further filters (F( omega ); 445) being wide-band 90* phase shifters (FIG. 4).
Claim 6
Dependent Claim
127 words
In an equalizer system according to claim 1, said filter bank containing a chain of delay elements (444), each of which has a delay T equal to the duration of a modulation interval; a further filter (F( omega ); 445) connected With each tap and with the input and output of the chain of delay elements (444), the taps of the chain of delay element (444), the input and output of the chain and also the outputs of said further filters (F( omega ); 445) being connected via variable elements (43, 30 to 33, 443, 430 to 433) with the inputs (35 to 39, 501, 401, 435 to 439) of an adder (40); said further filters (F( omega ); 445) being formed of differentiating circuits (FIG. 4).
Claim 7
Dependent Claim
16 words
In an equalizer system according to claim 5, said further filters being formed of integrating circuits.
Claim 8
Dependent Claim
16 words
In an equalizer system according to claim 5, said further filters being formed of all-pass circuits.
Claim 9
Dependent Claim
22 words
An equalizer system according to claim 1, comprising single-side band modulation means for subjecting the signal to a frequency-translation prior to equalization.
Claim 10
Dependent Claim
81 words
In an equalizer system according to claim 1, said computer comprising means for forming, for adaptive adjustment of said variable elements (30, 31, 33, 43, 443, 430 to 433), the partial derivatives of the sum of the error squares at the time points of the normal zero crossings (70 to 74) at the center of the modulation intervals thereby performing a differentiation with respect to the coefficients cj associated with said variable elements (30, 31, 33, 43, 443, 430 to 433).
Claim 11
Dependent Claim
87 words
In an equalizer system according to claim 1, said computer (12) comprising means for forming, for the adaptive adjustment of the variable elements (30, 31, 33, 43, 443, 430 to 433), the partial derivatives fo the sum of the absolute magnitudes of the error amplitudes at the time points of the normal zero crossings (70 to 74) at the center of the modulation intervals thereby performing a differentiation with respect to the coefficients (cj) associated with said variable elements (30, 31, 33, 43, 443, 430 to 433).
Claim 12
Dependent Claim
91 words
In an equalizer system according to claim 1, said computer (12) comprising means for determining, for the adaptive adjustment of the variable elements (30, 31, 33, 43, 443, 430 to 433), that one sign of the two possible signs of the partial derivatives of the absolute magnitudes of the error amplitudes, which occurs more frequently in the statistical average at the instants of normal zero crossings (70 to 74) thereby performing differentiation with respect to the coefficients (cj) associated with said variable elements (30, 31, 33, 43, 443, 430 to 433).
Claim 13
Dependent Claim
48 words
An equalizer system according to claim 1, comprising means for incrementally performing the adjustment of all of said variable elements (30 to 33, 43, 430 to 433, 443) in steps of variable width, in the width of said steps decreasing with increasingly improved adjustment of said equalizer (5).
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |