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US 5,125,100 AGranted
Optimal signal synthesis for distortion cancelling multicarrier systems
OwnerRon D. Katznelsoninventor
Life of this patent
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Abstract
A system and method for minimizing peak amplitudes and distortion in a communication system generating a composite signal. The present invention provides and maintains optimum phase conditions and a near-optimal set of auxiliary carriers in a closed-loop feedback system. An application to community antenna television (CATV) is disclosed.
Claims51
A system for generating a composite signal having a plurality of harmonically related signals, comprising:
- a signal generator for generating a plurality of harmonically related, receivable signals wherein the receivable signals have frequencies that are integral multiples of a preselected fundamental frequency;
- a signal generator for generating a plurality of harmonically related, auxiliary signals wherein the auxiliary signals have frequencies that are integral multiples of said fundamental frequency, the frequencies of the auxiliary signals selected so that they are different from the frequencies of said receivable signals, said auxiliary signals generated with specific phasor val so that peak-to-peak amplitude of said composite signal is less than that obtained from only combining the receivable signals;
- and
- a signal combiner that combines said receivable signals and said auxiliary signals thereby forming said composite signal.
1 more element
A system for generating a bilevel composite signal having a plurality of harmonically related signals, comprising:
- a signal generator for generating a plurality of harmonically related, receivable signals wherein the receivable signals have frequencies that are integral multiples of a preselected fundamental frequency;
- a signal generator for generating a plurality of harmonically related, auxiliary signals wherein the auxiliary signals have frequencies that are integral multiples of said fundamental frequency, the frequencies of the auxiliary signals selected so that they are different from the frequencies of said receivable signals, said auxiliary signals generated with specific phasor values so that the composite signal is substantially a bilevel signal;
- and
- a signal combiner that combines said receivable signals and said auxiliary signals thereby forming said bilevel composite signal.
1 more element
A multicarrier system, comprising:
- a signal generator that generates a composite signal, said composite signal comprising a plurality of harmonically related signals wherein the signals have frequencies that are integral multiples of a preselected fundamental frequency, and wherein each signal has a characteristic phasor;
- a distortion generator for processing said composite signal with a predetermined function so as to form a distorted composite signal comprising a plurality of nonlinearly derived signals, wherein each nonlinearly derived signal has a characteristic phasor;
- an analyzer that estimates the phasor value of at least a portion of the nonlinearly derived signals;
- and
- a phasor adjuster responsive to said analyzer that adjusts the phasor value of at least a portion of the signals of the composite signal thereby producing peak-to-peak amplitude of the composite signal.
2 more elements
A multicarrier controller for CATV, comprising:
- receivable signal generation means for generating a plurality of harmonically elated, receivable signals wherein the signals have frequencies that re integral multiples of a preselected fundamental frequency, and wherein each the receivable signals is characterized by a phase parameter;
- modulation means for impressing said receivable signals with television waveforms;
- auxiliary signal generation means or generating a plurality of harmonically related, auxiliary signals wherein the signals have frequencies that re integral multiples of said fundamental frequency, and wherein each of the auxiliary signals is characterized by a phasor, the frequencies of the auxiliary signals nonintersecting with the frequencies of said receivable signals;
- means for combining said modulated receivable signals and said auxiliary signals, thereby forming a composite signal having peak-to-peak amplitude less than that obtained from only combining the modulated receivable signals;
- nonlinear distortion means for processing said composite signal with a predetermined nonlinear function so as to form a distorted composite signal, the signals of the distorted composite signal having a harmonic relationship based on said fundamental frequency and wherein each of said signals of the distorted composite signal is characterized by a phasor;
- pahsor analyzer means for estimating phasor increments of said signals comprising the distorted composite signal;
- phase adjustment means responsive to said phasor analyzer means for adjusting the phase parameters of the receivable signals, said phase adjustment means in communication with said receivable signal generation means;
- and
- phasor adjustment means responsive to said phasor analyzer means for adjusting the phasor values of the auxiliary signals, said phasor adjustment means in communication with said auxiliary signal generation means.
6 more elements
A coherent multicarrier controller, comprising;
- carrier generation means for generating a set of harmonically related carriers for the transmission of television signals, each said carrier having a frequency that is an integral multiple of a predetermined fundamental frequency, wherein the phase of each carrier can be varied;
- modulation means in communication with said carrier generation means for modulating said harmonically related carriers with television signals received from an outside program source;
- signal combination means in communication with said modulation means for combining said modulated harmonically related carriers into a multicarrier signal;
- nonlinear sampling means in communication with said signal combination means for limiting the amplitude of said multicarrier signal nonlinearly so as to distort the phasor associated with each carrier;
- phasor estimation means in communication with said nonlinear sampling means or estimating each distortion phasor;
- and
- phase adjustment means in communication with said phasor estimation means for calculating a phase difference for each carrier, said phase difference communicated to said carrier generation mans for phase adjustment of said harmonically related carriers, thereby reducing peak-to-peak amplitude of said multicarrier signal.
4 more elements
In a system having a first group of harmonically related signals having frequencies that re integral multiples of a preselected fundamental frequency, a method for generating a composite signal with reduced peak-to-peak amplitude, said method comprising the steps of:
- generating a second group of harmonically related, auxiliary signals wherein the auxiliary signals have frequencies that are integral multiples of said fundamental frequency, the frequencies of the auxiliary signals selected so that the are different from the frequencies of said signals of the first group, said auxiliary signals generated with specific phasor values so that the peak-to-peak amplitude of said composite signal is less than that obtained from only combining the signals of the first group;
- and
- combining said first group of signals and said second group of auxiliary signals, thereby forming said composite signal.
In a system having a first group of harmonically related signals having frequencies that are integral multiples of a preselected fundamental frequency, a method for generating a bilevel composite signal, said method comprising the steps of:
- generating a second group of harmonically related, auxiliary signals wherein the auxiliary signals have frequencies that are integral multiples of said fundamental frequency, the frequencies of the auxiliary signals selected so that they are different from frequencies of said signals of the first group, said auxiliary signals generated with specific pahsor values so that the composite signal is substantially a bilevel signal;
- and
- combining said fist group of signals and said second group of auxiliary signals thereby forming said bilevel composite signal.
In a multicarrier system, a method of generating a composite signal with reduced peak-to-peak amplitude, said method comprising the steps of:
- generating a composite signal, said composite signal comprising a plurality of harmonically related signals wherein the signals have frequencies that are integral multiples of a preselected fundamental frequency, and wherein each signal has a characteristic phasor;
- distorting said composite signal with a predetermined nonlinear function so as to form a distorted composite signal comprising a plurality of nonlinearly derived signals wherein each nonlinearly derived signal has a characteristic phasor;
- estimating the characteristic phasor value of at least a portion of the nonlinearly derived signals;
- and
- adjusting the phasor value of at least a portion of the signals of said composite signal in accordance with a predetermined function of the phasor values of said nonlinearly derived signals, thereby reducing the peak-to-peak amplitude of said composite signal.
2 more elements
Dependencies are inferred from the claim text.