The paper proposed a new method for the detection of QPSK carrier signal that based on double duffing oscillator to solve the problems as high attenuation and strong noise interference in the QPSK carrier communication of low voltage power line. This method has making use of the different phase of QPSK carrier signal to stimulate the double duffing oscillators to enter different states and thro...

We experimentally demonstrate a tunable optical correlator to search for multiple patterns among QPSK symbols in 20 Gbuad stream. We use an optical frequency comb to generate coherent signals and add them coherently using a single PPLN waveguide. Multiple patterns with different lengths are successfully searched on QPSK signals.

We present a technique to derive -quadrature amplitude modulation (QAM) signals from quaternary phase-shift keying (QPSK) constellations when = 2 and is an even number. By utilizing QPSK Golay sequences, we have constructed -QAM sequences with low peak-to-mean envelope power ratios. Several upper bounds for these -QAM sequences were derived.

This paper presents new visualization techniques for 4D Quadrature-Quadrature Phase Shift Keying (QPSK), Saha’s Constant Envelope (CE) QPSK, and Cartwright’s CEQPSK in ideal bandlimited channels. The signal diagrams analyzed are: time-signal eye patterns for 4D passband signals, 2D complex trajectory diagrams of baseband signals, and time-signal eye patterns for the 1D outputs of the baseband m...

We demonstrate reconfigurable orbital angular momentum (OAM) and polarization manipulation of OAM- and polarization-multiplexed 100 Gbit/s quadrature phase shift keying (QPSK) data channels. Each data channel's OAM value and its polarization state can be arbitrarily changed by taking advantage of the unique wavefront profile of OAM beams using liquid crystal on silicon-based spatial light modul...

This letter investigates a distinct set of complex unitary matrices for differential space time coding by using QPSK modulation. The numerical results show that the properly selection of the initial transmission matrix and the set of unitary matrices can efficiently improve the bit error rate (BER) performance, especially for the antennas correlated fading channel. The computer simulations are ...

Due to great noise interference and strong signal attenuation in low voltage power line, two Duffing oscillator methods is proposed to detect QPSK carrier signal. At the same time, after analyzing the law of system solution of Duffing Oscillator, the algorithm of difference distribution of system solution is proposed to identify phase transition, which can greatly decrease calculation. The expe...

We demonstrate four wave mixing (FWM) based wavelength conversion of 40 Gbaud differential phase shift keyed (DPSK) and quadrature phase shift keyed (QPSK) signals in a 2.5 cm long silicon germanium waveguide. For a 290 mW pump power, bit error ratio (BER) measurements show approximately a 2-dB power penalty in both cases of DPSK (measured at a BER of 10(-9)) and QPSK (at a BER of 10(-3)) signa...

In many applications such as TDMA cellular telephone, OFDM, Bluetooth, Satellite communication etc. QPSK digital modulation technique is used due to its higher bandwidth efficiency, higher noise immunity and simpler circuit. Simpler circuit is having lower cost, smaller size and lower power dissipation. In this paper a new circuit for QPSK modulator is designed which improves the area of the ci...