US3679882A
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Fourier digital filter or equalizer and method of operation therefor
Assignee: International Business Machines Corp
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Filing: 1970-06-11
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Granted: 1972-07-25
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Expires: 1990-06-11
Abstract
Abstract An equalizer system is disclosed which includes a Fourier transform device having first and second input terminals and a separator connected to its output which provides a first output in the time domain and a second output in the frequency domain. A modified version of the second output is obtained by modifying it by a given filter characteristic. The first output and the modified second output are applied to first and second adding means wherein the values of the real and imaginary parts of these outputs are added algebraically to provide an equalized output in the time domain at the output of the first adding means while the output of the second adding means is applied via a feedback path to the second input terminal of the Fourier transform device along with an input on the first terminal thereof which occurs subsequent to the initial input applied to the first terminal. The method of operation consists in adding algebraically the values of the real and imaginary parts of a block of data which has been previously modified by a filter characteristic and transformed to the frequency domain to provide an output consisting of N parts; applying this output to a Fourier transform device to convert it to an apparent frequency domain of N complex parts; separating the output in the apparent frequency domain into frequency and time domain components each of N complex parts and, adding algebraically the values of the real and imaginary parts of the time domain component to provide an equalized or filtered block of data consisting of N real parts in the time domain.
Inventors
- 👤 Gerald K Mcauliffe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 10:10
CPC Classifications
H; H03; H03H; H03H17/00; H03H17/02; H03H17/0211; H03H17/0213; H04; H04B; H04B3/00; H04B3/02; H04B3/04; H04B3/14; H04B3/141
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
176 words
In a data modifying system including a transformation device having first and second input terminals, a separator connected to the output of said device providing a first transformed output at a first output and a second transformed output at a second output and means connected to said second output for modifying said second transformed output by a given characteristic comprising: first and second means connected to said first output and to said modifying means, respectively, for adding algebraically the values of the real and imaginary parts of said first output and said modified second output, respectively, to provide a modified version of an input applied to said input terminal at the output of said first adding means and a further modified output at the output of said second adding means, respectively, and feedback means connected to said second input terminal and said second adding means for applying the output of the latter to said second input terminal along with an input on said first terminal which is subsequent to said first-mentioned input on said first terminal.
Claim 2
Dependent Claim
176 words
In a data modifying system including a transformation device having first and second input terminals, a separator connected to the output of said device providing a first transformed output at a first output and a second transformed output at a second output and means connected to said second output for modifying said second transformed output by a given characteristic comprising: first and second means connected to said first output and to said modifying means, respectively, for adding algebraically the values of the real and imaginary parts of said first output and said modified second output, respectively, to provide a modified version of an input applied to said input terminal at the output of said first adding means and a further modified output at the output of said second adding means, respectively, and feedback means connected to said second input terminal and said second adding means for applying the output of the latter to said second input terminal along with an input on said first terminal which is subsequent to said first-mentioned input on said first terminal.
Claim 3
Dependent Claim
189 words
Apparatus for providing modified blocks of data in a first domain comprising: a transformation device having two input terminals, means for applying a first block of data in said first domain to one terminal of said device, means for separating the output of said device to provide at least a first block of data which has beEn converted to a second domain, means connected to said separating means for modifying said block of data in said second domain by a given characteristic to produce a modified first block of data in said second domain, first means connected to said modifying means for adding algebraically the value of the real and imaginary parts of said modified first block of data, means for applying the output of said adder to the other of said input terminals to carry out a transformation on said output of said adder, and second means connected to said separating means for adding algebraically the values of the real and imaginary parts of the output of said separator in the first domain to provide a modified version of said first block of data in said first domain.
Claim 4
Dependent Claim
189 words
Apparatus for providing modified blocks of data in a first domain comprising: a transformation device having two input terminals, means for applying a first block of data in said first domain to one terminal of said device, means for separating the output of said device to provide at least a first block of data which has beEn converted to a second domain, means connected to said separating means for modifying said block of data in said second domain by a given characteristic to produce a modified first block of data in said second domain, first means connected to said modifying means for adding algebraically the value of the real and imaginary parts of said modified first block of data, means for applying the output of said adder to the other of said input terminals to carry out a transformation on said output of said adder, and second means connected to said separating means for adding algebraically the values of the real and imaginary parts of the output of said separator in the first domain to provide a modified version of said first block of data in said first domain.
Claim 5
Dependent Claim
30 words
Apparatus according to claim 2 wherein said transformation device is capable of providing real and imaginary parts of a real function which are, respectively, even and odd or vice versa.
Claim 6
Dependent Claim
24 words
Apparatus according to claim 2 wherein said means for applying a first block of data in the said first domain includes a data receiver.
Claim 7
Dependent Claim
33 words
Apparatus according to claim 2 wherein said first and second means for adding are operational amplifiers which provide at their outputs the algebraic sum of the values of signals appearing at their inputs.
Claim 8
Dependent Claim
33 words
Apparatus according to claim 2 wherein said means for modifying includes a multiplier and means for generating a filter characteristic in said second domain to provide a modified output in said second domain.
Claim 9
Dependent Claim
27 words
Apparatus according to claim 6 wherein said means for generating a filter characteristic includes storage means for providing in digital form a block of N complex numbers.
Claim 10
Dependent Claim
225 words
Apparatus for providing modified blocks of data in a first domain comprising: a transformation device having two input terminals, means for applying a first block of data in said first domain to one terminal of said device, means for separating the output of said device to provide at least a first block of data which has been converted to a second domain, first means connected to said separating means for modifying said block of data in said second domain by a given characteristic to produce a modified first block of data in said second domain, means connected to said modifying means for adding algebraically the value of the real and imaginary parts of said modified first block of data, means connecting the output of said first adding means to the other of said input terminals for transforming said output of said first adding means to provide a transformed first adder input to said separating means, means for simultaneously applying a second block of data in said first domain to said one input terminal to provide a transformed second block of data, and second means connected to said separating means for adding algebraically the values of the real and imaginary parts of the output of said separator in the first domain to provide a modified version of said first block of data in said first domain.
Claim 11
Dependent Claim
225 words
Apparatus for providing modified blocks of data in a first domain comprising: a transformation device having two input terminals, means for applying a first block of data in said first domain to one terminal of said device, means for separating the output of said device to provide at least a first block of data which has been converted to a second domain, first means connected to said separating means for modifying said block of data in said second domain by a given characteristic to produce a modified first block of data in said second domain, means connected to said modifying means for adding algebraically the value of the real and imaginary parts of said modified first block of data, means connecting the output of said first adding means to the other of said input terminals for transforming said output of said first adding means to provide a transformed first adder input to said separating means, means for simultaneously applying a second block of data in said first domain to said one input terminal to provide a transformed second block of data, and second means connected to said separating means for adding algebraically the values of the real and imaginary parts of the output of said separator in the first domain to provide a modified version of said first block of data in said first domain.
Claim 12
Dependent Claim
195 words
Apparatus for providing equalized or filtered blocks of data in the time domain comprising: a Fourier transform device having two input terminals, means for applying a first block of data in the time domain to one terminal of said device, means for separating the output of said device to provide at least a first block of data which has been converted to the frequency domain, means connected to said separating means for modifying said first block of data in the frequency domain by a given filter characteristic to produce a modified first block of data in the frequency domain, first means connected to said modifying means for adding algebraically the value of the real and imaginary parts of said modified first block of data in the frequency domain, means for applying the output of said adder to the other of said input terminals to carry out a Fourier transformation on said output of said adder, and second means connected to said separating means for adding algebraically the values of the real and imaginary parts of an output of said separator in the time domain to provide an equalized version of said first block of data.
Claim 13
Dependent Claim
195 words
Apparatus for providing equalized or filtered blocks of data in the time domain comprising: a Fourier transform device having two input terminals, means for applying a first block of data in the time domain to one terminal of said device, means for separating the output of said device to provide at least a first block of data which has been converted to the frequency domain, means connected to said separating means for modifying said first block of data in the frequency domain by a given filter characteristic to produce a modified first block of data in the frequency domain, first means connected to said modifying means for adding algebraically the value of the real and imaginary parts of said modified first block of data in the frequency domain, means for applying the output of said adder to the other of said input terminals to carry out a Fourier transformation on said output of said adder, and second means connected to said separating means for adding algebraically the values of the real and imaginary parts of an output of said separator in the time domain to provide an equalized version of said first block of data.
Claim 14
Dependent Claim
33 words
Apparatus according to claim 9 wherein said first and second means for adding are operational amplifiers which provide at their outputs the algebraic sum of the values of signals appearing at their inputs.
Claim 15
Dependent Claim
230 words
Apparatus for providing equalized or filtered blocks of data in the time domain comprising: a Fourier transform device having two input terminals means for applying a first block of data in the time domain to one terminal of said device, means for separating the output of said device to provide at least a first block of data which has been converted to the frequency domain, means connected to said separating means for modifying said first block of data in the frequency domain by a given filter characteristic to produce a modified first block of data in the frequency domain, first means connected to said modifying means for adding algebraically the value of the real and imaginary parts of said modified first block of data in the frequency domain, means connecting the output of said first adding means to the other of said input terminals for transforming said output of said first adding means to provide a transformed first adder input to said separating means, means for simultaneously applying a second block of data in said first domain to said one input terminal to provide a transformed second block of data, and, second means connected to said separating means for adding algebraically the values of the real and imaginary parts of an output of said separator in the time domain to provide an equalized version of said first block of data.
Claim 16
Dependent Claim
230 words
Apparatus for providing equalized or filtered blocks of data in the time domain comprising: a Fourier transform device having two input terminals means for applying a first block of data in the time domain to one terminal of said device, means for separating the output of said device to provide at least a first block of data which has been converted to the frequency domain, means connected to said separating means for modifying said first block of data in the frequency domain by a given filter characteristic to produce a modified first block of data in the frequency domain, first means connected to said modifying means for adding algebraically the value of the real and imaginary parts of said modified first block of data in the frequency domain, means connecting the output of said first adding means to the other of said input terminals for transforming said output of said first adding means to provide a transformed first adder input to said separating means, means for simultaneously applying a second block of data in said first domain to said one input terminal to provide a transformed second block of data, and, second means connected to said separating means for adding algebraically the values of the real and imaginary parts of an output of said separator in the time domain to provide an equalized version of said first block of data.
Claim 17
Dependent Claim
33 words
Apparatus according to claim 11 wherein said first and second means for adding are operational amplifiers which provide at their outputs the algebraic sum of the values of signals appearing at their inputs.
Claim 18
Dependent Claim
33 words
Apparatus according to claim 11 wherein said means for modifying includes a multiplier and means for generating a filter characteristic in the frequency domain to provide a modified output in the frequency domain.
Claim 19
Dependent Claim
27 words
Apparatus according to claim 13 wherein said means for generating a filter characteristic includes storage means for providing in digital form a block of N complex numbers.
Claim 20
Dependent Claim
174 words
In a method for modifying a block of data consisting of N real parts in a first domain, which has been previously applied to one of a pair of terminals of a transformation device, transformed to a second domain, separated and modified by a given characteristic to provide a transformed and modified first block of data in a second domain, the steps of: adding algebraically the values of the real and imaginary parts of said block of data in said second domain to provide an output consisting of N parts, applying said output consisting of N parts to the other of said pair of terminals of said transformation device to convert said output to N complex parts in an apparent second domain, separating said output in the apparent second domain into second domain and first domain components each of N complex parts, and adding algebraically the values of the real and imaginary parts of said first domain component to provide a modified block of data consisting of N real parts in the first domain.
Claim 21
Dependent Claim
174 words
In a method for modifying a block of data consisting of N real parts in a first domain, which has been previously applied to one of a pair of terminals of a transformation device, transformed to a second domain, separated and modified by a given characteristic to provide a transformed and modified first block of data in a second domain, the steps of: adding algebraically the values of the real and imaginary parts of said block of data in said second domain to provide an output consisting of N parts, applying said output consisting of N parts to the other of said pair of terminals of said transformation device to convert said output to N complex parts in an apparent second domain, separating said output in the apparent second domain into second domain and first domain components each of N complex parts, and adding algebraically the values of the real and imaginary parts of said first domain component to provide a modified block of data consisting of N real parts in the first domain.
Claim 22
Independent Claim
178 words
A method for providing modified blocks of data in a first domain comprising the steps of: applying a first block of data in the first domain to one input terminal of a transformation device which has two input terminals, separating the output of said device in a separator to provide at least a first block of data which has been converted to a second domain, modifying said first block of data in the second domain by a given characteristic in a multiplier, adding algebraically the values of the real and imaginary pArts of said modified first block of data in the second domain in an adder, applying the output of said adder to the other of said input terminals and transforming said output of said adder, separating the output of said device in said separator to provide at least a transformed adder output in the first domain, and adding algebraically the values of the real and imaginary parts of said transformed adder output to provide a modified version of said first block of data in the first domain.
Claim 23
Independent Claim
178 words
A method for providing modified blocks of data in a first domain comprising the steps of: applying a first block of data in the first domain to one input terminal of a transformation device which has two input terminals, separating the output of said device in a separator to provide at least a first block of data which has been converted to a second domain, modifying said first block of data in the second domain by a given characteristic in a multiplier, adding algebraically the values of the real and imaginary pArts of said modified first block of data in the second domain in an adder, applying the output of said adder to the other of said input terminals and transforming said output of said adder, separating the output of said device in said separator to provide at least a transformed adder output in the first domain, and adding algebraically the values of the real and imaginary parts of said transformed adder output to provide a modified version of said first block of data in the first domain.
Claim 24
Independent Claim
211 words
A method for providing modified blocks of data in a first domain comprising the steps of: applying a first block of data in the first domain to one input terminal of a transformation device which has two input terminals, separating the output of said device in a separator to provide at least a first block of data which has been converted to a second domain, modifying said first block of data in the second domain by a given characteristic in a multiplier, adding algebraically the values of the real and imaginary parts of said modified first block of data in the second domain in an adder, applying the output of said adder to the other of said input terminals while simultaneously applying a second block of data in the first domain to said one input terminal and transforming said output of said adder and said second block of data, separating the output of said device in said separator to provide a transformed adder output in the first domain and a transformed second block of data output in the second domain, and adding algebraically the values of the real and imaginary parts of said transformed adder output to provide a modified version of said first block of data in the first domain.
Claim 25
Independent Claim
211 words
A method for providing modified blocks of data in a first domain comprising the steps of: applying a first block of data in the first domain to one input terminal of a transformation device which has two input terminals, separating the output of said device in a separator to provide at least a first block of data which has been converted to a second domain, modifying said first block of data in the second domain by a given characteristic in a multiplier, adding algebraically the values of the real and imaginary parts of said modified first block of data in the second domain in an adder, applying the output of said adder to the other of said input terminals while simultaneously applying a second block of data in the first domain to said one input terminal and transforming said output of said adder and said second block of data, separating the output of said device in said separator to provide a transformed adder output in the first domain and a transformed second block of data output in the second domain, and adding algebraically the values of the real and imaginary parts of said transformed adder output to provide a modified version of said first block of data in the first domain.
Claim 26
Dependent Claim
65 words
A method according to claim 17 wherein said first block of data consists of N real parts, said output of said device consists of N complex parts, said output of said adder in the second domain consists of N real parts, said transformed adder output consists of N complex parts and said modified version of said first block of data consists of N real parts.
Claim 27
Dependent Claim
176 words
In a method for filtering a block of data consisting of N real parts in the time domain which has been previously applied to one of a pair of terminals of a Fourier transform device, transformed to a second domain, separated and modified by a given characteristic to provide a transformed and modified first block of data in a second domain, the steps of: adding algebraically the values of the real and imaginary parts of said block of data in said second domain to provide an output consisting of N parts, applying said output consisting of N parts to the other of said pair of terminals of said Fourier transform device to convert said output to N complex parts in an apparent frequency domain, separating said output in the apparent frequency domain into frequency domain and time domain components each of N complex parts, and adding algebraically the values of the real and imaginary parts of said time domain component to provide an equalized block of data consisting of N real parts in the time domain.
Claim 28
Dependent Claim
176 words
In a method for filtering a block of data consisting of N real parts in the time domain which has been previously applied to one of a pair of terminals of a Fourier transform device, transformed to a second domain, separated and modified by a given characteristic to provide a transformed and modified first block of data in a second domain, the steps of: adding algebraically the values of the real and imaginary parts of said block of data in said second domain to provide an output consisting of N parts, applying said output consisting of N parts to the other of said pair of terminals of said Fourier transform device to convert said output to N complex parts in an apparent frequency domain, separating said output in the apparent frequency domain into frequency domain and time domain components each of N complex parts, and adding algebraically the values of the real and imaginary parts of said time domain component to provide an equalized block of data consisting of N real parts in the time domain.
Claim 29
Independent Claim
185 words
A method for providing equalized blocks of data in the time domain comprising the steps of: applying a first block of data in the time domain to one input terminal of a Fourier transform device which has two input terminals, separating the output of said device in a separator to provide at least a first block of data which has been converted to the frequency domain, modifying said first block of data in the frequency domain by a given filter characteristic in a multiplier, adding algebraically the values of the real and imaginary parts of said modified first block of data in the frequency domain in an adder, applying the output of said adder to the other of said input terminals and carrying out a Fourier transformation on said output of said adder, separating the output of said device in said separator to provide at least A transformed adder output in the time domain, and adding algebraically the values of the real and imaginary parts of said transformed adder output to provide an equalized version of said first block of data in the time domain.
Claim 30
Independent Claim
185 words
A method for providing equalized blocks of data in the time domain comprising the steps of: applying a first block of data in the time domain to one input terminal of a Fourier transform device which has two input terminals, separating the output of said device in a separator to provide at least a first block of data which has been converted to the frequency domain, modifying said first block of data in the frequency domain by a given filter characteristic in a multiplier, adding algebraically the values of the real and imaginary parts of said modified first block of data in the frequency domain in an adder, applying the output of said adder to the other of said input terminals and carrying out a Fourier transformation on said output of said adder, separating the output of said device in said separator to provide at least A transformed adder output in the time domain, and adding algebraically the values of the real and imaginary parts of said transformed adder output to provide an equalized version of said first block of data in the time domain.
Claim 31
Independent Claim
219 words
A method for providing equalized blocks of data in the time domain comprising the steps of: applying a first block of data in the time domain to one input terminal of a Fourier transform device which has two input terminals, separating the output of said device in a separator to provide at least a first block of data which has been converted to the frequency domain, modifying said first block of data in the frequency domain by a given filter characteristic in a multiplier, adding algebraically the values of the real and imaginary parts of said modified first block of data in the frequency domain in an adder, applying the output of said adder to the other of said input terminals while simultaneously applying a second block of data in the time domain to said one input terminal and carrying out a Fourier transformation on said output of said adder and on said second block of data, separating the output of said device in said separator to provide a transformed adder output in the time domain and a transformed second block of data output in the frequency domain, and adding algebraically the values of the real and imaginary parts of said transformed adder output to provide an equalized version of said first block of data in the time domain.
Claim 32
Independent Claim
219 words
A method for providing equalized blocks of data in the time domain comprising the steps of: applying a first block of data in the time domain to one input terminal of a Fourier transform device which has two input terminals, separating the output of said device in a separator to provide at least a first block of data which has been converted to the frequency domain, modifying said first block of data in the frequency domain by a given filter characteristic in a multiplier, adding algebraically the values of the real and imaginary parts of said modified first block of data in the frequency domain in an adder, applying the output of said adder to the other of said input terminals while simultaneously applying a second block of data in the time domain to said one input terminal and carrying out a Fourier transformation on said output of said adder and on said second block of data, separating the output of said device in said separator to provide a transformed adder output in the time domain and a transformed second block of data output in the frequency domain, and adding algebraically the values of the real and imaginary parts of said transformed adder output to provide an equalized version of said first block of data in the time domain.
Claim 33
Dependent Claim
65 words
A method according to claim 21 wherein said first block of data consists of N real parts, said output of said device consists of N complex parts, said output of said adder in the frequency domain consists of N real parts, said transformed adder output consists of N complex parts and said equalized version of said first block of data consists of N real parts.
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) | 1975-07-25 | 1976-01-24 | 1976-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-25 | 1980-01-24 | 1980-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-25 | 1984-01-24 | 1984-07-25 | $7700.00 | Window Closed / Lapsed |