Continuous integration digital demodulator for use in a communication device
First Claim
1. A digital demodulator comprising:
- an oscillator generating as output an oscillator clock signal;
a frequency divider coupled to the oscillator clock signal, wherein the oscillator generates the oscillator clock signal at a first frequency and the frequency divider divides the oscillator clock signal by a divider factor to generate a sampling clock signal at a second;
a mixer coupled to the sampling clock signal, the mixer suitable for receiving as input a limited IF signal derived from a received radio frequency (RF) signal and sampling the limited IF signal in accordance with the sampling clock signal to generate as output a resulting IF signal;
a continuous integrator connected to the mixer and coupled to the sampling clock signal, the continuous integrator integrating the resulting IF signal over a predetermined number of samples of the limited IF signal to generate a numerical value representative of a modulation frequency of a baseband signal, the continuous integrator being driven by the sampling clock signal and generating as output a numerical value for each sample of the limited IF signal; and
a peak-valley bit slicer connected to the continuous integrator and to the oscillator, the peak-valley bit slicer comparing each numerical value with thresholds to determine corresponding digital data of the baseband signal.
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Abstract
A digital demodulator (100) for use in a communication device comprising a mixer (110) which samples a limited IF signal derived from a received radio frequency (RF) signal at a rate less than a Nyquist rate of the limited IF signal and generates a resulting IF signal. A continuous integrator (130) is connected to the mixer (110) and integrates the resulting IF signal over a predetermined number of samples thereof to generate a numerical value representative of a modulation frequency of a limited IF signal. An adaptive peak-valley bit slicer (150) is connected to the continuous integrator (130) and compares each numerical value with a peak threshold, a valley threshold and a mid threshold and generates most-significant-bit (MSB) and least-significant-bit (LSB) values for each sample. The adaptive peak-valley bit slicer (150) adjusts the peak and valley thresholds for use in determining a level of a current numerical value based on the LSB and MSB values determined for a prior sample of the numerical value.
115 Citations
29 Claims
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1. A digital demodulator comprising:
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an oscillator generating as output an oscillator clock signal; a frequency divider coupled to the oscillator clock signal, wherein the oscillator generates the oscillator clock signal at a first frequency and the frequency divider divides the oscillator clock signal by a divider factor to generate a sampling clock signal at a second; a mixer coupled to the sampling clock signal, the mixer suitable for receiving as input a limited IF signal derived from a received radio frequency (RF) signal and sampling the limited IF signal in accordance with the sampling clock signal to generate as output a resulting IF signal; a continuous integrator connected to the mixer and coupled to the sampling clock signal, the continuous integrator integrating the resulting IF signal over a predetermined number of samples of the limited IF signal to generate a numerical value representative of a modulation frequency of a baseband signal, the continuous integrator being driven by the sampling clock signal and generating as output a numerical value for each sample of the limited IF signal; and a peak-valley bit slicer connected to the continuous integrator and to the oscillator, the peak-valley bit slicer comparing each numerical value with thresholds to determine corresponding digital data of the baseband signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A digital demodulator for use in a receiver comprising:
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an oscillator generating as output an oscillator clock signal; a frequency divider coupled to the oscillator and receiving as input the oscillator clock signal and frequency dividing the oscillator clock signal by a divider factor to generate as output a sampling clock signal; a mixer coupled to the sampling clock signal, the mixer suitable for receiving as input a limited IF signal derived from a received radio frequency (RF) signal and sampling the limited IF signal in accordance with the sampling clock signal derived from the oscillator clock signal to generate as output a resulting IF signal; a continuous integrator connected to the mixer and coupled to the sampling clock signal, the continuous integrator integrating the resulting IF signal over a predetermined number of samples of the limited IF signal to generate a numerical value representative of a modulation frequency of a baseband signal, the continuous integrator being driven by the sampling clock signal and generating as output a numerical value for each sample of the limited IF signal; an adaptive peak-valley bit slicer connected to the continuous integrator and to the sampling clock signal, the adaptive peak-valley bit slicer comparing each numerical value with a peak threshold, a valley threshold and a mid threshold and generating digital data comprising most-significant-bit (MSB) and least-significant-bit (LSB) values for each sample, wherein the adaptive peak-valley bit slicer adjusts the peak and valley thresholds for use in determining a level of a current sample of the numerical value based on the LSB and MSB values determined for a prior sample. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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29. In combination, a digital demodulator and control means for controlling the digital demodulator, the digital demodulator comprising:
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an oscillator generating as output an oscillator clock signal; a frequency divider connected to the oscillator and receiving as input the oscillator clock signal and frequency dividing the oscillator clock signal by a divider factor to generate as output a sampling clock signal; a mixer connected to the frequency divider, the mixer suitable for receiving as input a limited IF signal derived from a received radio frequency (RF) signal and sampling the limited IF signal in accordance with the sampling clock signal to generate as output a resulting IF signal; a continuous integrator connected to the frequency divider and coupled to the oscillator, the continuous integrator integrating the resulting IF signal over a predetermined number of samples of the limited IF signal, the continuous integrator being driven by the sampling clock signal and generating a preliminary numerical value for each sample of the limited IF signal, the continuous integrator comprising a multiplier for multiplying the preliminary numerical value by a multiplier factor in order to generate a numerical value representative of a modulation frequency of a baseband signal; and a peak-valley bit slicer connected to the continuous integrator and to the oscillator, the peak-valley bit slicer comparing each numerical value with thresholds to determine corresponding digital data of the baseband signal; wherein the control means controls the divider factor of the frequency divider and the multiplier factor of the multiplier depending upon an expected baud rate of the digital data in the baseband signal.
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Specification