Qpsk demodulator
AssigneeNational Chiao Tung University
InventorsChi-Yi LO, Hao-Chiao Hong
Life of this patent
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Abstract
A novel quadrature phase-shift keying (QPSK) demodulator, called the bowknot quadrature phase-shift keying (BQPSK) demodulator, is disclosed. The BQPSK demodulator uses a delay circuit to delay a BQPSK signal and mixes the delayed BQPSK signal with the undelayed BQPSK signal to output an I-channel data signal and a Q-channel data signal. The BQPSK demodulator further uses a phase rotation circuit to demodulate the orthogonal data signals and obtain a recovery clock signal. The BQPSK demodulator neither uses an A/D converter nor uses a quadrature oscillator, featuring high data rate, low power consumption, simple architecture and superior reliability. The BQPSK demodulator can be realized by digital circuits and analog circuits.
Claims19
A bowknot quadrature phase-shift keying demodulator comprising
- a delay circuit, receiving a bowknot quadrature phase-shift keying (BQPSK) signal, delaying said BQPSK signal by a first delay time to output a first delayed signal, and delaying said BQPSK signal by a total delay time to output a second delayed signal or an opposite-phase second delayed signal, wherein said opposite-phase second delayed signal is an opposite-signal of said second delayed signal;
- and
- a decision-making circuit, electrically connected with said delay circuit, mixing said BQPSK signal with said second delayed signal or said opposite-phase second delayed signal to generate a first heterodyne signal, sampling said BQPSK signal according to said first heterodyne signal to output an I-channel data signal of said BQPSK signal, mixing said first delayed signal with said BQPSK signal to generate a second heterodyne signal, and sampling said second heterodyne signal according to said first heterodyne signal to output a Q-channel data signal of said BQPSK signal, wherein said first delay time and said total delay time meets following relationships:
- 0.125T≦TD1≦0.375T, 0.375T<TD<0.625T, 0.125T≦TD−TD1<0.5T, wherein TD is said total delay time, TD1 is said first delay time, and T is a period of a carrier wave of said BQPSK signal.
(canceled)
Dependencies are inferred from the claim text.