Communication system with demodulation of two-level differential amplitude-shift-keying signals
First Claim
1. A two-level differential amplitude-shift-keying (D-ASK) signal demodulator for demodulating an amplitude bit of an input signal, comprising:
- a first envelope detector for detecting an amplitude of the input signal and providing an amplitude signal of the input signal;
a first delay unit for delaying the amplitude signal of the input signal to generate a delayed amplitude signal;
a first subtractor for subtracting the delayed amplitude signal from the amplitude signal of the input signal;
a second envelope detector for detecting an amplitude signal of an output signal from the first subtractor;
a threshold value generator for receiving the amplitude signal of the input signal and generating a threshold value dynamically; and
a comparator for comparing the output of the second envelope detector with the threshold value produced by the threshold value generator, determining if there is any change between the amplitude of the consecutive input signals, and outputting a comparison result as the amplitude bit of the input signal.
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Abstract
A structure and method for demodulating two-level differential amplitude-shift-keying signals using simple adding operations are provided. Threshold values are dynamically adjusted according to the channel response. By comparing the threshold values and the differential amplitude values, it can be found whether the amplitude of the received signal is changed. Furthermore, it no needs to know the changed value of received signal amplitudes and the differential two-level amplitude-shift-keying signals can be demodulated by just detecting whether the amplitude of the received signal is changed. By this idea, the complexity of the receiver implementation is simplified and the demodulator can get better performance.
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Citations
13 Claims
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1. A two-level differential amplitude-shift-keying (D-ASK) signal demodulator for demodulating an amplitude bit of an input signal, comprising:
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a first envelope detector for detecting an amplitude of the input signal and providing an amplitude signal of the input signal;
a first delay unit for delaying the amplitude signal of the input signal to generate a delayed amplitude signal;
a first subtractor for subtracting the delayed amplitude signal from the amplitude signal of the input signal;
a second envelope detector for detecting an amplitude signal of an output signal from the first subtractor;
a threshold value generator for receiving the amplitude signal of the input signal and generating a threshold value dynamically; and
a comparator for comparing the output of the second envelope detector with the threshold value produced by the threshold value generator, determining if there is any change between the amplitude of the consecutive input signals, and outputting a comparison result as the amplitude bit of the input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of demodulating a two-level differential amplitude-shift-keying (D-ASK) signal, comprising:
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receiving an input signal generated from adding a channel effect to a two-level D-ASK signal;
detecting an amplitude of the input signal to generate an amplitude signal;
delaying the amplitude signal to generate a delayed amplitude signal;
dynamically generating a threshold value according to the amplitude signal, wherein the threshold value responds to the channel effect;
obtaining a difference value between the amplitude signal and the delayed amplitude signal;
detecting an amplitude of the difference value; and
comparing the amplitude of the difference value with the threshold value, wherein the comparison result is used to determine an amplitude bit of the input signal. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification