Method of crossover region phase correction when summing signals in multiple frequency bands
First Claim
1. A method for adjusting a phase relationship between signals from multiple frequency bands that are being summed to reduce potential destructive interference therebetween, comprising the steps of:
- identifying a crossover region corresponding to a frequency range in which a lower frequency content signal overlaps with a higher frequency content signal;
determining a magnitude difference between a magnitude of the lower frequency content signal and a magnitude of the higher frequency content signal in the crossover region, a small magnitude difference being indicative of a possibility of excessive destructive interference between the signals;
comparing the determined magnitude difference to a predetermined threshold to determine whether the determined magnitude difference is less than the predetermined threshold;
if it is determined that the determined magnitude difference is less than the predetermined threshold, determining a phase difference in the crossover region between the signals and adjusting a phase of one of the signals so that the phase difference between the signals is reduced, thereby reducing the possibility of excessive destructive interference between the signals; and
combining the adjusted signal with the other of the signals, thereby producing a composite frequency content having a substantially reduced crossover region phase error, and a substantially reduced likelihood of destructive interference between the signals.
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Abstract
A signal processing system compensates for the relative phase difference between multiple frequency bands so that the combination of the bands is constructive throughout a substantial portion of the band overlap or crossover region. In one embodiment, a signal combining system may include a comparator for determining a relative phase difference between the two signals within a predefined crossover region, a phase adjusting element for adjusting a phase of one of the two signals; and a combiner for combining the phase-adjusted signal and the other of the two signals.
61 Citations
17 Claims
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1. A method for adjusting a phase relationship between signals from multiple frequency bands that are being summed to reduce potential destructive interference therebetween, comprising the steps of:
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identifying a crossover region corresponding to a frequency range in which a lower frequency content signal overlaps with a higher frequency content signal; determining a magnitude difference between a magnitude of the lower frequency content signal and a magnitude of the higher frequency content signal in the crossover region, a small magnitude difference being indicative of a possibility of excessive destructive interference between the signals; comparing the determined magnitude difference to a predetermined threshold to determine whether the determined magnitude difference is less than the predetermined threshold; if it is determined that the determined magnitude difference is less than the predetermined threshold, determining a phase difference in the crossover region between the signals and adjusting a phase of one of the signals so that the phase difference between the signals is reduced, thereby reducing the possibility of excessive destructive interference between the signals; and combining the adjusted signal with the other of the signals, thereby producing a composite frequency content having a substantially reduced crossover region phase error, and a substantially reduced likelihood of destructive interference between the signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for improving a response upon the combination of two signals to reduce potential destructive interference therebetween, comprising the steps of:
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determining a magnitude difference between the two signals in a crossover region between the two signals, a small magnitude difference being indicative of a possibility of excessive destructive interference between the signals; comparing the determined magnitude difference to a predetermined threshold to determine whether the determined magnitude difference is less than the predetermined threshold; if it is determined that the determined magnitude difference is less than the predetermined threshold, determining a relative phase difference between the two signals within the crossover region; adjusting a phase of one of the two signals to reduce a phase difference therebetween; and combining the phase-adjusted signal and the other of the two signals. - View Dependent Claims (11, 12, 13, 14)
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15. A system for improving a response upon the combination of two or more signals to reduce potential constructive interference therebetween, comprising:
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a comparator for comparing a magnitude difference between the two or more signals in a crossover region therebetween to a predetermined threshold to determine whether the magnitude difference is less than the predetermined threshold; a phase adjusting element for adjusting a phase of one or more of the two or more signals if it is determined that the magnitude difference is less than the predetermined threshold, thereby reducing the possibility of excessive destructive interference between the signals, said phase adjusting element employing one or more filter coefficient and delay specification; and a combiner for combining the phase-adjusted signals and the other of the signals. - View Dependent Claims (16, 17)
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Specification