Digital demodulator using numerical processor to evaluate period measurements
First Claim
1. A digital demodulator for efficient demodulation of temporally modulated signals, the demodulator comprising:
- a zero-crossing event detector, responsive to a temporally modulated signal, that serves to detect zero-crossing events of said temporally modulated signal, and thereby provide zero-crossing event information;
a period measurer, connected to said zero-crossing detector, that serves to receive said zero-crossing event information and measure the period between said zero-crossing events, thereby providing a sequence of period measurement values; and
a numerical processor, connected to said period measurer, that serves to convert said sequence of period measurement values into a demodulated signal with a high signal-to-noise ratio.
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Abstract
A digital demodulator provides efficient demodulation of frequency modulated, pulse-width modulated, and other temporally modulated signals. Without employing an analog-to-digital converter, modulating signal information is extracted from a modulated signal as numerical information. For frequency demodulation, a high gain stage is applied to an incoming FM signal to produce a corresponding sequence of square waves. The period between zero-crossings of the square waves is accurately measured to within one clock pulse using a high-speed clock and at least one counter. Period information is then provided to a numerical processor, wherein it is at least scaled and low-pass filtered to produce a high-quality demodulated signal with a high signal-to-noise ratio.
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Citations
15 Claims
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1. A digital demodulator for efficient demodulation of temporally modulated signals, the demodulator comprising:
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a zero-crossing event detector, responsive to a temporally modulated signal, that serves to detect zero-crossing events of said temporally modulated signal, and thereby provide zero-crossing event information; a period measurer, connected to said zero-crossing detector, that serves to receive said zero-crossing event information and measure the period between said zero-crossing events, thereby providing a sequence of period measurement values; and a numerical processor, connected to said period measurer, that serves to convert said sequence of period measurement values into a demodulated signal with a high signal-to-noise ratio. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for demodulating a temporally modulated signal, the method comprising the steps of:
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measuring the period between zero-crossings of an intermediate signal of a modulated signal to provide a sequence of period values; and numerically processing said sequence of period values to provide a demodulated signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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Specification