US3864632A
Expired / Lapsed
US
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Fast Equalization System
Assignee: Boeing North American Inc
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Filing: 1973-10-01
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Granted: 1975-02-04
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Expires: 1993-10-01
Abstract
Abstract A discrete frequency domain equalization system is disclosed for utilization in a high-speed synchronous data transmission system where, in a preferred embodiment, samples of an input signal in the time domain are transformed by a discrete fast Fourier transform device into samples in the frequency domain. Reciprocal values of these frequency domain samples are derived from a reciprocal circuit and then transformed by an inverse discrete fast Fourier transform device into time domain samples which are the desired tap gains that are applied to a transversal equalizer in order to minimize the errors in a received signal caused by intersymbol interference and noise.
Inventors
- 👤 Tien-Lin Chang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 02:07
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03159; H04L2025/03433; H04L2025/03439; H04L2025/03522
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
130 words
An equalization system for automatically adjusting the tap settings of a transversal equalizer to correct for distortions of a data signal received from a transmission channel, said system comprising: first means responsive to a first signal in the time domain from the transmission channel for developing time domain samples of the first signal; second means for performing a discrete fast Fourier transform on the time domain samples of the first signal to develop samples in the frequency domain; third means for developing reciprocal values of the samples in the frequency domain; and fourth means for performing an inverse discrete fast Fourier transform on said reciprocal values of the samples in the frequency domain to develop time domain tap gains for automatically adjusting the tap settings in the transversal equalizer circuit
Claim 2
Dependent Claim
130 words
An equalization system for automatically adjusting the tap settings of a transversal equalizer to correct for distortions of a data signal received from a transmission channel, said system comprising: first means responsive to a first signal in the time domain from the transmission channel for developing time domain samples of the first signal; second means for performing a discrete fast Fourier transform on the time domain samples of the first signal to develop samples in the frequency domain; third means for developing reciprocal values of the samples in the frequency domain; and fourth means for performing an inverse discrete fast Fourier transform on said reciprocal values of the samples in the frequency domain to develop time domain tap gains for automatically adjusting the tap settings in the transversal equalizer circuit
Claim 3
Dependent Claim
125 words
The system of claim 1 wherein said first means includes: means for selectively sampling said first signal and said data signal received from the transmission channel to develop samples thereof in the time domain; means coupled to the transmission channel for generating a first control signal when the first signal is being received from the transmission channel and for generating a second control signal when the data signal is being received from the transmission channel; fifth means having first and second outputs for allowing samples of the first signal to be passed to said first output in response to the first control signal and for allowing samples of the data signal to be passed to said second output in response to the second control signal.
Claim 4
Dependent Claim
26 words
The system of claim 1 wherein: said second means is a fast Fourier transform device; and said fourth means is an inverse fast Fourier transform device.
Claim 5
Dependent Claim
126 words
The system of claim 3 wherein said first means includes: means for selectively sampling said first signal and said data signal received from the transmission channel to develop samples thereof in the time domain; means coupled to the transmission channeL for generating a first control signal when the first signal is being received from the transmission channel and for generating a second control signal when the data signal is being received from the transmission channel; and fifth means having first and second outputs for allowing samples of the first signal to be passed to said first output in response to the first control signal and for allowing samples of the data signal to be passed to said second output in response to the second control signal.
Claim 6
Dependent Claim
45 words
The system of claim 4 further including: a first source for generating the first signal: a second source for generating the data signal; and means coupled to said first and second sources for selectively transmitting the first signal and data signal into the transmission channel.
Claim 7
Dependent Claim
80 words
The system of claim 5 wherein said transmitting means includes: sixth means coupled to said first and second sources for selectively permitting the first signal and the data signal to be transmitted into the transmission channel; and seventh means for controlling said sixth means to pass the first signal to the transmission channel during a first mode of operation and for controlling said sixth means to pass the data signal to the transmission channel during a second mode of operation.
Claim 8
Independent Claim
198 words
A system for adjusting the tap settings in a transversal equalizer circuit adapted to be responsive to a transmission channel, said system comprising: a first signal source for generating test pulse signals; a second signal source for generating digital data signals; first means for applying test pulse signals to the transmission channel during a first mode of operation and for applying the digital data signals to the transmission channel during a second mode of operation; second means being responsive to the signals received from the transmission channel for developing samples of the test pulse signals during the first mode of operation and for developing and applying samples of the digital data signals to the transversal equalizer circuit during the second mode of operation: third means for performing a discrete fast Fourier transform on the samples of the test pulse signals to develop samples in the frequency domain; fourth means for developing reciprocal values of the samples in the frequency domain; and fifth means for performing an inverse discrete fast Fourier transform on the reciprocal values of the samples in the frequency domain to develop time domain tap gains for automatically adjusting the tap settings in the transversal equalizer.
Claim 9
Independent Claim
198 words
A system for adjusting the tap settings in a transversal equalizer circuit adapted to be responsive to a transmission channel, said system comprising: a first signal source for generating test pulse signals; a second signal source for generating digital data signals; first means for applying test pulse signals to the transmission channel during a first mode of operation and for applying the digital data signals to the transmission channel during a second mode of operation; second means being responsive to the signals received from the transmission channel for developing samples of the test pulse signals during the first mode of operation and for developing and applying samples of the digital data signals to the transversal equalizer circuit during the second mode of operation: third means for performing a discrete fast Fourier transform on the samples of the test pulse signals to develop samples in the frequency domain; fourth means for developing reciprocal values of the samples in the frequency domain; and fifth means for performing an inverse discrete fast Fourier transform on the reciprocal values of the samples in the frequency domain to develop time domain tap gains for automatically adjusting the tap settings in the transversal equalizer.
Claim 10
Independent Claim
409 words
A system adapted to equalize data signals transmitted through a transmission channel of limited bandwidth, said system comprising: a first source for generating first signals; a second source for generating data signals; a first switching circuit being responsive to first and second states of a first control signal for selectively controlling the passage of the first signals and data signals therethrough to the transmission channel; a first control circuit for generating and applying the first control signal to said first switching circuit, said first switching circuit being responsive to the first and second states of the first control signal for respectively passing the first and data signals to the transmission channel; means being responsive to signals from the transmission channel for providing samples thereof; a second control circuit coupled to the transmission channel for generating a first state second control signal when first signals are being passed through the transmission channel and for generating a second state second control signal when data signals are being passed through the transmission channel; a second switching circuit having first and second output terminals, said second switching circuit being responsive to the second control signal for applying samples of the first signals to said first output terminal when the second control signal iS in the first state and for applying samples of the data signals to said second output terminal when the second control signal is in the second state; a transversal equalizer circuit having a plurally tapped delay circuit coupled to said second switching circuit, a plurality of adjustable tap gains coupled to respective taps of said tapped delay circuit, and a summation circuit coupled to said adjustable tap gains, said transversal equalizer circuit being responsive to the application of samples of the data signals from said second switching circuit to said delay circuit for providing output equalized data signals as a function of the adjustment of said adjustable tap gains; transformation means being responsive to the samples of the first signals from said first output terminal for transforming same from a time domain to a frequency domain, and a reciprocal circuit being responsive to the frequency domain samples of the first signals for developing and applying reciprocal values of the frequency domain samples to said transformation means, said transformation means being responsive to the reciprocal values of the frequency domain samples for transforming same into time domain tap gain signals to adjust said adjustable tap gains in said transversal equalizer circuit.
Claim 11
Independent Claim
409 words
A system adapted to equalize data signals transmitted through a transmission channel of limited bandwidth, said system comprising: a first source for generating first signals; a second source for generating data signals; a first switching circuit being responsive to first and second states of a first control signal for selectively controlling the passage of the first signals and data signals therethrough to the transmission channel; a first control circuit for generating and applying the first control signal to said first switching circuit, said first switching circuit being responsive to the first and second states of the first control signal for respectively passing the first and data signals to the transmission channel; means being responsive to signals from the transmission channel for providing samples thereof; a second control circuit coupled to the transmission channel for generating a first state second control signal when first signals are being passed through the transmission channel and for generating a second state second control signal when data signals are being passed through the transmission channel; a second switching circuit having first and second output terminals, said second switching circuit being responsive to the second control signal for applying samples of the first signals to said first output terminal when the second control signal iS in the first state and for applying samples of the data signals to said second output terminal when the second control signal is in the second state; a transversal equalizer circuit having a plurally tapped delay circuit coupled to said second switching circuit, a plurality of adjustable tap gains coupled to respective taps of said tapped delay circuit, and a summation circuit coupled to said adjustable tap gains, said transversal equalizer circuit being responsive to the application of samples of the data signals from said second switching circuit to said delay circuit for providing output equalized data signals as a function of the adjustment of said adjustable tap gains; transformation means being responsive to the samples of the first signals from said first output terminal for transforming same from a time domain to a frequency domain, and a reciprocal circuit being responsive to the frequency domain samples of the first signals for developing and applying reciprocal values of the frequency domain samples to said transformation means, said transformation means being responsive to the reciprocal values of the frequency domain samples for transforming same into time domain tap gain signals to adjust said adjustable tap gains in said transversal equalizer circuit.
Claim 12
Dependent Claim
51 words
The system of claim 8 wherein said transformation means is a fast Fourier transform device for performing a discrete fast Fourier transform on the samples of the first signals and for performing an inverse discrete fast Fourier transform on the reciprocal values of the frequency domain samples from said reciprocal circuit.
Claim 13
Dependent Claim
78 words
The system of claim 8 wherein said transformation means includes: a fast Fourier transform device for performing a discrete fast Fourier transform on the samples of the first signals to transform them into frequency domain samples of the first signals; and an inverse fast Fourier transform device for performing an inverse discrete fast Fourier transform on the reciprocal values of the frequency domain samples from said reciprocal circuit to transform them into the time domain tap gain signals.
Claim 14
Dependent Claim
155 words
An equalization system for automatically adjusting the tap settings of a transversal equalizer to correct for distortions of a data signal received from a transmission channel, said system comprising: sampling means responsive to a first signal in the time domain from the transmission channel for developing time domain samples of the first signal; a transformation device responsive to the time domain samples of the first signal for performing a discrete fast Fourier transform thereon to transform them into frequency domain samples of the first signal; and a reciprocal circuit responsive to the frequency domain samples of the first signal for developing and applying reciprocal values of the frequency domain samples to said transformation device, said transformation device being responsive to the reciprocal values of the frequency domain samples for performing an inverse discrete fast Fourier transform thereon to transform them into time domain tap gain signals to adjust the tap settings in the transversal equalizer.
Claim 15
Dependent Claim
155 words
An equalization system for automatically adjusting the tap settings of a transversal equalizer to correct for distortions of a data signal received from a transmission channel, said system comprising: sampling means responsive to a first signal in the time domain from the transmission channel for developing time domain samples of the first signal; a transformation device responsive to the time domain samples of the first signal for performing a discrete fast Fourier transform thereon to transform them into frequency domain samples of the first signal; and a reciprocal circuit responsive to the frequency domain samples of the first signal for developing and applying reciprocal values of the frequency domain samples to said transformation device, said transformation device being responsive to the reciprocal values of the frequency domain samples for performing an inverse discrete fast Fourier transform thereon to transform them into time domain tap gain signals to adjust the tap settings in the transversal equalizer.
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) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |