Research of Hybrid Modulation Radar Signal

Based on the advantage of phase coded signal and stepped frequency signal,a new hybrid modulation signal is introduced in this paper. It combines phase code modulation during the pulse with stepped frequency modulation between the pulses, which is named as phase-coded stepped-frequency ( PCSF ) signal. By analyzing its waveform and ambiguity function,the comparison between Stepped-Frequency ( SF) signal and PCSF signal is given,which shows that the PCSF signal is better than SF signal. Finally,the signal processing method with two stage compressed processing is presented. The simulation results show that this new hybrid modulation radar signal can get a higher stepped frequency than ordinary SF signal,realize the same equivalent bandwidth with less pulse number,and solve the conflict among the stepped frequency,the number of pulse, and transmit average power. Under the premises of a certain range resolution,this new hybrid modulation radar signal not only raises the data rate of radar system,but also reduces Doppler sensitivity with a good prospect, and the effect of one-dimensional range profile is much better than that of traditional SF signal. Therefore,this new hybrid modulation radar signal can be widely used in application.

PDM-DPSK-MPPM hybrid modulation for multi-hop free-space optical communication

A hybrid polarization division multiplexed-differential phase shift keying-multipulse pulse position modulation(PDM-DPSK-MPPM) scheme for multi-hop free-space optical(FSO) communication is investigated. The analytical bit error rate(BER) of the proposed system in Gamma-Gamma turbulence channels is derived and verified using computer simulation. The results show that both multi-hop and hybrid modulation schemes are efficient techniques to improve the performance of FSO links. Compared with the traditional binary phase shift keying(BPSK) and MPPM, the hybrid scheme can improve the bandwidth-utilization efficiency and reliability of the system. Compared with the coherent demodulation of PDM-QPSK-MPPM, the system complexity is reduced at the cost of the degradation of BER performance, which can improve the practicality of hybrid modulation technology in FSO system.

A Full-Duplex PON with Hybrid 64/16/4QAM OFDM Downlink and Hybrid 16/8/QPSK OFDM Uplink

In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8/QPSK-OFDM signal for uplink transmission is successfully proposed and experimentally presented in a full-duplex PON based on OFDM system. Here, for the uplink, in order to unit management of the optical line terminal (OLT) and reduce cost, the optical source functioned as the optical subcarrier at optical network units (ONUs) is from OLT in the central station. Moreover, there is an external cavity laser (ECL) with center frequency of 193.2 THz not only employed as optical modulated signal but also acted as LO signal. Our simulation results show that bit error ratio (BER) under hardware detection forward error correction has been successfully gained after 20 km of SSMF transmission. It is observed that the receiver sensitivity of multilevel PSK (M-PSK) is obviously larger than that of the M-QAM in this measurement scheme.

Organic electro-optic polymer materials and organic-based hybrid electro-optic modulators

High performance electro-optic modulator,as the key device of integrated ultra-wideband optical systems,have be-come the focus of research.Meanwhile,the organic-based hybrid electro-optic modulators,which make full use of the advant-ages of organic electro-optic(OEO)materials(e.g.high electro-optic coefficient,fast response speed,high bandwidth,easy pro-cessing/integration and low cost)have attracted considerable attention.In this paper,we introduce a series of high-perform-ance OEO materials that exhibit good properties in electro-optic activity and thermal stability.In addition,the recent progress of organic-based hybrid electro-optic devices is reviewed,including photonic crystal-organic hybrid(PCOH),silicon-organic hy-brid(SOH)and plasmonic-organic hybrid(POH)modulators.A high-performance integrated optical platform based on OEO ma-terials is a promising solution for growing high speeds and low power consumption in compact sizes.

Hybrid Renewable Energy Source Combined Dynamic Voltage Restorer for Power Quality Improvement

In this paper,the hybrid photovoltaic-thermoelectric generator(PVTEG)combined dynamic voltage restorer(DVR)system is proposed for the power quality disturbances compensation in a single-phase distribution system.The stable and precise level of input voltage is essential for the smooth and trouble-free operation of the electrically sensitive loads which are connected at the utility side to avoid system malfunctions.In this context,the hybrid PV-TEG energy module combined DVR system is proposed in this paper.With the support of the hybrid energy module,the DVR will perform the power quality disturbances compensation effectively with needed voltage and/or power.In the proposed system,the PV and TEG energy sources are connected electrically in series to produce adequate voltage for the DVR operation and the fractional factor-based variable incremental conduction(FFVINC)maximum power point tracking(MPPT)control algorithm is employed to extract the possible maximum power from the PV array.The intelligent fuzzy logic controller(FLC)is chosen for implementing the MPPT control algorithm.The half-bridge voltage source inverter(VSI)circuit and in-phase voltage compensation technique are used in the DVR for better power quality disturbances compensation.The performance and usefulness of the proposed DVR system are investigated by an extensive simulation study with four different modes of operation,the study results are confirmed that the proposed system promptly identifies the power quality disturbances for compensation.Moreover,the investigation proved that the combined PV and TEG energy module can provide better energy efficiency in converting solar irradiation into electricity.

Performance and Stability of Supercapacitor Modules based on Porous Carbon Electrodes in Hybrid Powertrain

Hybrid power sources have attracted much attention in the electric vehicle area. Particularly, electric-electric hybrid powertrain system consisting of supercapacitor modules and lithium-ion batteries has been widely applied because of the high power density of supercapacitors. In this study, we design a hybrid powertrain system containing two porous carbon electrode-based supercapacitor modules in parallel and one lithium ion battery pack. With the construction of the testing station, the performance and stability of the used supercapacitor modules are investigated in correlation with the structure of the supercapacitor and the nature of the electrode materials applied. It has been shown that the responding time for voltage vibration from 20 V to 48.5 V during charging or discharging process decreases from about 490 s to 94 s with the increase in applied current from 20 A to 100 A. The capacitance of the capacitor modules is nearly independent on the applied current. With the designed setup, the energy efficiency can reach as high as 0.99. The results described here provide a guidance for material selection of supercapacitors and optimized controlling strategy for hybrid power system applied in electric vehicles.

Hybrid Simulation of Duty Cycle Influences on Pulse Modulated RF SiH_4/Ar Discharge

A one-dimensional fluid/Monte-Carlo（MC）hybrid model is developed to describe capacitively coupled SiH_4/Ar discharge,in which the lower electrode is applied by a RF source and pulse modulated by a square-wave,to investigate the modulation effects of the pulse duty cycle on the discharge mechanism.An electron Monte Carlo simulation is used to calculate the electron energy distribution as a function of position and time phase.Rate coefficients in chemical reactions can then be obtained and transferred to the fluid model for the calculation of electron temperature and densities of different species,such as electrons,ions,and radicals.The simulation results show that,the electron energy distribution f（ε）is modulated evidently within a pulse cycle,with its tail extending to higher energies during the power-on period,while shrinking back promptly in the afterglow period.Thus,the rate coefficients could be controlled during the discharge,resulting in modulation of the species composition on the substrate compared with continuous excitation.Meanwhile,more negative ions,like Si H_3^-and Si H_2^-,may escape to the electrodes owing to the collapse of ambipolar electric fields,which is beneficial to films deposition.Pulse modulation is thus expected to provide additional methods to customize the plasma densities and components.

A Hybrid Si IGBT and SiC MOSFET Module Development

A compact wirebond packaged phase-leg SiC/Si hybrid module was designed,developed,and tested.Details of the layout and gate drive designs are described.The IC chip for gate drive is carefully selected and compared.Dual pulse test confirmed that,the switching loss of hybrid module is close to pure SiC MOSFET module,and it is much less than pure Si IGBT device.The cost of hybrid module is closer to Si IGBT.

An Improved Hybrid Space Vector PWM Technique for IM Drives

In this paper, an improved hybrid space vector pulse width modulation (HSVPWM) technique is proposed for IM (induction motor) drives. The basic principle involved in the proposed random pulse width modulation (RPWM) cuddled SVPWM is amalgamating the pre-calculated switching timings for various sections of hexagonal space vector boundary and the random selection of carrier between two triangular signals, in order to disband acoustic switching noise spectrum with improved fundamental component. The arbitrary selection between triangular carriers, which is decided by digital signal states (Low or High) of the linear feedback shift register (LFSR) based pseudo random binary sequence (PRBS) generator. The SVPWM offers a control degree of freedom in terms of positioning of vectors inside every sampling interval and hence it has six possible variants of the voltage vectors arrangements in each sector. The developed HSVPWM is thoroughly analyzed in using the MATLAB? based simulation for all SVPWM variants. From the simulation and experimental results viz. harmonic spectrum, harmonic spread factor (HSF), total harmonic distortion (THD) etc., and the superiority of the proposed scheme such as better utilization of DC bus and the randomization of the harmonic power are evidenced. For the practical implementation, Xilinx XC3S500E FPGA device has been used.

Experimental Results of MHD Suppression with Modulated LHCD on the HT-7 Tokamak

Modulation of lower hybrid current drive was used successfully to suppress MHD activity. This was achieved in discharges with MHD m = 2 tearing modes during the discharge conditions Ip = 110 kA, Bt = 1.75 T, ne0 - 1.1 × 1013 cm-3. The delivering time of LHCD pulse is less then 30 μs. The amplitude, interval and the period of LHCD modulation pulse can be adjusted very conveniently. The modulation LHCD can be delivered very fast at any time during the discharge. The modulation LHCD period was always much shorter than the plasma resistive time (Tη ≈100 ms). So the profile of plasma current is changed much faster than the plasma resistive time. The different forms of LHCD modulating can be proved.

Review of Si IGBT and SiC MOSFET Based on Hybrid Switch

SiC Hybrid switch(HyS)combines low conduction loss of Si IGBT and low switching loss of SiC MOSFET,and the cost is closer to that of Si IGBT.The promising high performances of HyS will bring considerable achievement in terms of enhancing power density of a converter system.By reviewing the gate drive pattern,gate drive hardware,current sharing,module design,converter design,and cost,this paper introduces state-of-the-art SiC HyS.

112 Gbit/s transmitter optical subassembly based on hybrid integrated directly modulated lasers

Based on the hybrid integration technology, an ultra-compact and low cost transmitter optical subassembly module is proposed. Four directly modulated lasers are combined with a coarse wavelength division multiplexer operated at the O-band. The bandwidth for all channels is measured to be approximately 3 GHz. The 112 Gb∕s transmission is experimentally demonstrated for a 10 km standard single mode fiber（SSMF）, in which an optical isolator is used for avoiding the back-reflected and scattered light to improve the bit error rate（BER） performance. A low BER and clear eye opening are achieved for 10 km transmission.

Error rate performance of Hybrid QAM-FSK in OFDM systems exhibiting low PAPR

Multicarrier transmission systems like orthogonal frequency division multiplexing （OFDM） support high data rate and generally require no equalization at the receiver, making them simple and efficient. This paper studies the design and performance analysis of a hybrid modulation system derived from multifrequency and MQAM signals, employed in OFDM. This modulation scheme has better bit error rate （BER） performance and exhibits low PAPR. The proposed hybrid modulator reduces PAPR while keeping the OFDM transceiver design simple, as it does not require any side information or a little side information （only one bit） to be sent and is efficient for arbitrary number of subcarriers. The results of the implementations are compared with those of conventional OFDM system.

The development and application of the test system for the silicon pixel modules in HEPS-BPIX

Background HEPS-BPIX is a prototype of photon counting pixel detector developed for the High Energy Photon Source.It consists of 16 silicon pixel modules which should be tested individually to ensure the function and performance.Purpose Due to various factors such as the non-uniformity of the processes and voltage drop,the response of each pixel in the silicon pixel module is not identical completely.The response difference of pixels can be minimized by the threshold calibration.This system is developed for the quality test and calibration of the silicon pixel modules.Methods The system consists of a mother board,a control board and a data acquisition(DAQ)system.The mother board provides necessary resources including power supplies and the fanout of calibration signals.Besides,it can be used to test the connectivity by monitoring the power states.The control board reads data out and provides the clock,trigger and configuration data for the silicon pixel module.The DAQ system sends the control commands and receives the readout data through an Ethernet link.Results Compared with the previous readout system,this designed system has a lower noise level and better scanning curves making the calibration more accurate.And it has been successfully applied to the comparison experiments of the through silicon via and wire-bonding silicon pixel modules.Conclusion The results show that this test system can be used to the quality test and calibration of the silicon pixel modules.In addition,the system can be adapted to the measurement of different pixel array detector modules.