Advanced Materials Research Vols. 760-762

Abstract: In the digital transmission system, an efficient fractionally-spaced equalizer (FSE) for blind equalization based on modified constant modulus algorithm (MCMA) and phase locked loop (PLL) is proposed. Comparing with conventional FSE based on famous CMA, the proposed algorithm has not only lower steady-state mean square error and faster convergence rate but also the ability to recover carrier phase rotation. The efficiency of the method is proved by computer simulation.

Abstract: Ultra-wide-band (UWB) is a promising short-range indoor wireless communication technology for large communication capacity, high transmission rate, low power consumption, etc. Multi-band orthogonal frequency-division multiplexing ultra-wide-band (MB-OFDM UWB) system can achieve much higher anti-noise capability and flexibility. However, the transmission power of UWB systems is strictly restricted for avoiding the interference with other wireless communication systems existing in the same frequency spectrum range. It is necessary that adequately utilizes channel estimation to allocate bit and power effectively. According to the change of channel gain, UWB systems modify the allocation factor to optimize the performance of systems and reduce power allocation remainder. Simulation shows modified bit-power allocation algorithm can enhance power allocation efficiency. Furthermore, it is found that the power remainder of modified allocation factor algorithm is less influenced by the bit error rate.

Abstract: In the digital transmission system, constant modulus algorithm (CMA) is a famous blind equalization to overcome the inter-symbol interference without the aid of training sequences. But for the non-constant modulus signals such as higher-order QAM signals, the CMA just achieve moderate steady-state mean square error (MSE). So a new dual-mode fractionally-spaced equalization (FSE) suitable for high-order QAM signals is proposed, which makes full use of the character which is that the high-order QAM signals have the different modulus. This algorithm uses the FSE based on CMA as the basal mode and in the second mode it uses the FSE based on variable modulus algorithm. The simulation results show that compared with CMA the proposed algorithm has faster convergence rate and lower steady-state mean square error.

Abstract: The Eu complexes-Eu (TTA)₃phen (TTA: thenoyltrifluoroacetone, phen: 1,10-phenanthroline) were encapsulated, uniformly distributed into the channels of the modified SBA-15 (labeled with MSBA-15), and structurally characterized. The photoluminescence properties of the encapsulated complexes were systematically studied in contrast to the pure complexes. The results indicate that the excitation bands assigned to the π-π* electron transition of the ligands for Eu³⁺ complexes in encapsulated complexes were split into different components, and the ⁵D₀-⁷F₀ transitions became partly allowed. The emission lines for the ⁵D₀-⁷F₂ transitions became broader and the relative intensity for different crystal field components varied greatly in comparison to the pure complex. Most importantly, the photostability and thermostability of the emissions improved considerably.

Abstract: In order to solve the problem of design and optimization for E-shaped patch microstrip antenna, chaotic particle swarm optimization (CPSO) algorithm was proposed to assist the procedure. First, the E-shaped antennas model was created, and then, the parameters of this antenna were adjusted according to the CPSO algorithm, and the procedure was repeated until the antennas capabilities meet the requirements. The simulation results showed that, the optimized model of such antenna, was capable of dual-frequency operation in 1.8GHz and 2.4GHz, and it was also capable of wide bandwidth, could meet the requirements very well.

Abstract: The rapid development of the Terahertz technology has been the essential focus among all application fields. In order to applying the spectral technology to the security and analyzing all exploders spectrum characteristics, the paper aims to three exploders spectrums researches including the HNS, DNMT and DNAN. The three reflected spectrums are tested and analyzed, using the most advanced portable terahertz spectrometer, and the absorption peaks among 0.1~2.5THz are determined successfully.

Abstract: Since the resolution of digital micro-mirror device (DMD) which is used to reconstruct the digital holograms captured in experiments is relatively low, only a part of the digital hologram can be effectively reproduced in the experiment. For the hologram has the feature of high redundancy, in this paper, we propose that compress holograms based on Binary holographic interference. First, only the amplitude of the digital hologram is retained after Fresnel diffraction, recover the phase information from the amplitude, then generate a new compressed digital hologram with the phase and amplitude, and then process the new hologram according to the principle of binary holographic interference to improve the diffraction efficiency and to obtain a high-quality reconstruction.

Abstract: In order to eliminate the zero-order and conjugate image in off-axis digital holography, a new method based on the spatial filtering of the hologram illuminated with the reference (written as RI_h) wave is proposed. By using RI_h and the low-pass filter to do the convolution operation, the real image of the object without the zero-order and conjugate image is directly obtained. Simultaneously, the real image always appears in the center of the reconstructed image plane. The spectrum characteristic of RI_h is analyzed. A comparative analysis of the spectrum characteristics of the hologram and RI_h is discussed. The theoretical and experiment results show that: this method requires only one hologram, and do once Fourier transform. The process of designing filtering window is simple and convenient.

Abstract: Design a high-precision real-time high-speed sampling fiber grating demodulation signal system based on a USB2.0 interface and FPGA; system hardware design and software design are introduced in detail. It is proved that has a good reliability and stability by the experiment. So this design has a strong value in use.

Abstract: Synchronous jitter is one of the factors that influence GPS receiving precision a lot. Jitter is the effective data offset off the ideal position in a data stream, which is divided into deterministic jitter and random jitter. A theoretical analysis was done to the influence of jitter. It can be seen that bit error rate gets larger due to the jitter of synchronous clock. By means of a simulation platform, a simulation was done to the synchronous jitter influence on bit error rate in the circumstance of white noise and single frequency interference. The result shows that as the synchronous jitter gets larger, the system bit error rate gets larger and the system function gets worse.