System for extracting timing information from a digital waveform
First Claim
1. A method of extracting timing information from an original waveform representing digital information and composed of elementary signals, the method comprising transforming the original waveform into a transformed waveform by the steps of modulating a carrier wave with the original waveform, passing the modulated waveform through a surface acoustic wave transversal filter and demodulating the output of the filter to produce said transformed waveform and detecting zero crossings of the demodulated signal, the characteristics of the surface acoustic wave transversal filter being such as to transform an isolated elementary signal in the original waveform into an elementary transformed waveform which has at least one zero crossing and is substantially zero at each instant at which a zero crossing of any other elementary transformed waveform can occur, and outputting timing signals in response to the detection of zero crossings in the demodulated signal.
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Abstract
System for extracting timing information from a digital waveform supplied to the system in which the waveform is modulated by a modulator, passed through a surface acoustic wave transversal filter and demodulated by a demodulator. Zero crossings in the resultant transformed waveform are detected by a detector and used to determine the times at which another version of the original waveform is sampled by a sampling circuit.
The characteristics of the surface acoustic wave transversal filter are chosen to be such that each elementary pulse in the original waveform is transformed into an oscillatory waveform, the zero crossings of the different oscillatory waveforms coinciding with one another and defining the sampling times.
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10 Claims
- 1. A method of extracting timing information from an original waveform representing digital information and composed of elementary signals, the method comprising transforming the original waveform into a transformed waveform by the steps of modulating a carrier wave with the original waveform, passing the modulated waveform through a surface acoustic wave transversal filter and demodulating the output of the filter to produce said transformed waveform and detecting zero crossings of the demodulated signal, the characteristics of the surface acoustic wave transversal filter being such as to transform an isolated elementary signal in the original waveform into an elementary transformed waveform which has at least one zero crossing and is substantially zero at each instant at which a zero crossing of any other elementary transformed waveform can occur, and outputting timing signals in response to the detection of zero crossings in the demodulated signal.
- 6. Apparatus for extracting timing information from an original waveform representing digital information and composed of elementary signals, the apparatus comprising means for transforming the original waveform into a transformed waveform, which means comprises in sequence a modulator for modulating a carrier wave with the original waveform, a surface acoustic wave transversal filter for passing the modulated waveform and a demodulator for demodulating the filter output to produce said transformed waveform and means for detecting zero crossings of the demodulated signal and outputting timing signals in response thereto, the characteristics of the surface acoustic wave transversal filter being such as in operation to transform an isolated elementary signal in the original waveform into an elementary transformed waveform which has at least one zero crossing and is substantially zero at each instant at which a zero crossing of any other elementary transformed waveform can occur.
Specification