Modulation distortion reducer
First Claim
1. Distortion reducing apparatus for a distorted double-sideband amplitude modulated carrier with sidebands of unequal amplitude or unequal phase relationship to the carrier, or both, which comprises an amplitude modulator which receives said distorted modulated carrier and delivers the modulated carrier with reduced distortion to an output circuit, and an angle modulation detection and compensation circuit, which receives said modulated carrier with at least some angle modulation and delivers its output as a modulating wave to said amplitude modulator with a phase and level which cause said modulator to substantially reduce the distortion of said distorted modulated wave.
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Abstract
A double-sideband amplitude modulated (DSBAM) carrier passed through band-pass circuits wich are too narrow for the modulated carrier or are misaligned, may have one or both side-bands altered in relative amplitude, or in phase relative to the carrier. These effects result in amplitude modulation distortion and produce angle modulation of the carrier, with the same waveform as the amplitude distortion. In this invention the angle modulation is detected and applied to an amplitude modulator in the required phase and amplitude to substantially eliminate the distortion of the modulated carrier.
14 Citations
3 Claims
- 1. Distortion reducing apparatus for a distorted double-sideband amplitude modulated carrier with sidebands of unequal amplitude or unequal phase relationship to the carrier, or both, which comprises an amplitude modulator which receives said distorted modulated carrier and delivers the modulated carrier with reduced distortion to an output circuit, and an angle modulation detection and compensation circuit, which receives said modulated carrier with at least some angle modulation and delivers its output as a modulating wave to said amplitude modulator with a phase and level which cause said modulator to substantially reduce the distortion of said distorted modulated wave.
Specification