Advanced Materials Research Vol. 462

Abstract: In recent years, as the indoor wireless communication has gained increasing attention, various kinds of wireless communication techniques have developed rapidly to obtain a better system performance. Chirp signal is also noticed again due to the feature of low power consumption, high processing gain and low cost. A novel M-ary chirp modulation technique is proposed in this paper to increase the system performance both under AWGN channel and indoor wireless channel. Optimal linear chirp signals are designed in this system to reduce the cross correlation, and simplify the complexity of the system. Simulation shows that, compared with the binary orthogonality modulation technique, the M-ary chirp modulation technique using optimal linear chirp signal has a high data rate with a reasonable BER both under AWGN channel and indoor wireless channel.

Abstract: Traditional energy detection algorithm is bad in anti-noise. In this paper, the relationship of energy detection performance and detection sensitivity with average noise power fluctuation in short time is investigated. Detection sensitivity drops quickly with the increment of average noise power fluctuation and becomes worse in low signal-to-noise ratio. To the characteristic, a new energy detection algorithm based on dynamic threshold is presented. Theoretic results and simulations show that the proposed scheme removes the falling proportion of performance and detection sensitivity caused by the average noise power fluctuation with a choice threshold, and also improves the antagonism of the average noise power fluctuation in short time and obtains a good performance. Detection sensitivity and performance improves as the dynamic threshold factor increasing.

Abstract: In cognitive radio networks, nodes should have the capability to decide whether a signal from a primary transmitter is locally present or not in a certain spectrum within a short detection period. Traditional spectrum sensing schemes based on fixed threshold are sensitive to noise uncertainty, a fractional fluctuate of average noise power in a short time can lead the performance of spectrum detection drop seriously. This paper presents a new spectrum detection algorithm based on dynamic threshold. Theoretical results show that the proposed scheme debate the noise uncertainty, and good detection performance can be gained, if suitable dynamic threshold is chosen. In other words, the proposed scheme can enhance the robustness against noise and improve the capacity of spectrum sensing.

Abstract: The diode model for EMC is built on the basis of lumped charge model. The model consists of forward recovery, reverse recovery and carrier recombination and is completed by MAST modeling language in Saber. The simulation results show that this model describes the forward and reverse recovery correctly.

Abstract: This paper presents a design method for communication module design in semiconductor equipment simulation platform. There are several kinds of standardized protocols in semiconductor equipments intra communication, the method with which these standardized protocols can be configured and integrated in single simulation platform. These protocols can be configured statically and dynamically respectively. In static state, protocol configuration provides various protocols for chosen and edit. In the dynamic state, the virtual devices can be communicated with control system with communication module. As a case study, a process chamber system simulator with designed the communication module has been illustrated. The designed communication module accomplishes the data transmission between control system and the chamber simulation system. The devices in chamber system receive the instruction form control system and execute the required actions. The experiment results show that the simulation platform is feasible and effective.

Abstract: Based on ISO/IEC 18000-6 Type B protocol, 915MHz RFID reader has been designed. FPGA is used to process the digital signal that is based on the protocol and C8051F020 is used as the controller. Each module in FPGA and verification module is designed by Verilog HDL. They are synthesized by Quartus II with EP1C6Q240C8 CMOS chip of the Altera as the target device, and they are verified on both timing and function. The result shows that it could satisfy the technology index of ISO/IEC18000-6 Type B requests and possess the advantages of flexible structure, small size and easily upgrading, etc.

Abstract: The analyses of the simulation of a single mode buried waveguide optical phase modulator based on SOI material are here reported. The structure has been simulated by Athena from Silvaco simulation package. The buried waveguide is created by doping phosphorus with concentration of 10e15 cm-3 into the substrate. The real refractive index and the absorption coefficient of the waveguide are changed using the free carrier dispersion effect via carrier injection of a pn junction. The efficiency, VπLπ is calculated and the performance is compared with that of the rib waveguide optical phase modulator of the same material and dimensions. Simulation shows that the device can be an efficient device for application in intensity modulation.

Abstract: To take full advantage of high brightness, wide color gamut and high saturation of the Laser TV, kinds of gamut expansion methods emerged. Most of the methods are based on the hue unchangeable principle. So before gamut expansion, the boundary of Laser TV gamut and that of current display standard gamut should be first obtained. But the traditional method for getting the device color gamut based on physical model was not accurate enough for the Laser TV gamut expansion. Based on this situation, An improved gamut boundary description method based on graham algorithm for laser TV was proposed in this paper. The method first used Convex Hull Algorithm to detect the edge points on the convex edge, and then through multiple iterations to calculate the Concave edge points between the convex edge points. Result of experiment on the CIE L*a*b* color space showed this kind of method could give a more accurate description of the Laser TV gamut boundary.

Abstract: In order to accomplish the optimal design of the most small reduction device of gear-worm, the mathematics model was established and the optimal results was achieved by the method of punishment function. And it has been compared with the traditional design methods.

Abstract: An applicable passive location algorithm of target based on single fixed-site illuminator of opportunity is introduced in this paper. The azimuth can be acquired using DBF (digital beam formation) technique and angle-measuring via amplitude comparison. Based on Time Difference of Arrival (TDOA), the distance between the target and the radar station is achievable. Finally, the accuracy of location is analyzed, and the computer simulation results are presented.