共查询到20条相似文献,搜索用时 609 毫秒
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文中介绍了G.726语音编解码算法的原理,详细论述了ADPCM编解码算法在DSPTMS320VC5509A上实现的硬件结构及软件算法,并给出了在实现过程中的程序优化方法. 相似文献
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系统研究了现有语音通信系统中使用的几种语音编解码算法以及主流的单通道语音增强算法,并将二者相结合,对实际通信系统中的结构进行仿真.研究发现,现有的基于线性预测分析技术的语音编解码算法,在高编码率的情况下对于语音增强算法的性能不仅不会有损失,反而会在一定程度上改善增强算法带来的语音失真的情况,提高语音增强算法的效果. 相似文献
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首先介绍了ITU-TG.729A建议的编解码算法,然后根据此算法的特点,并结合实际系统的应用要求,介绍了基于此建议的语音管理系统的实现。整个系统完全采用软件编制,并达到了编解码的实时性,有较高的实用价值。 相似文献
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对G.729编解码算法的原理进行了简要分析,并提出了一种基于TMS320C54x的G.729语音编解码算法的实现方法.针对算法特征及DSP体系结构的特点,提出了一些有效的优化措施.仿真结果表明,运算复杂度大大降低,而重建语音具有很好的编解码效果. 相似文献
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G.728是ITU-T于1992年制定的比特率为16kbit/s的语音编解码标准,采用低时延码激励线性预测(LD-CELP)算法。文中介绍了G.728语音编解码算法的基本原理,并给出在视频会议系统中实现该算法时的优化策略。 相似文献
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本文介绍了 G.723.1语音编解码算法及 LSI Logic 公司推出的一种基于 ZSP400内核的定点 DSP(LSI402ZX),设计了一个用于可视电话的语音编解码子系统,并描述了 G.723.1算法在 LSI402ZX 上的实时实现方法,从而实现了实时语音传输的功能。 相似文献
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介绍了ITU-T G.72 3.1标准和FD216的特征.分析了以FD216实现编解码系统的设计要点,设计了G.72 3.1实时语音编解码系统.该系统实现了ITU-T G.72 3.1标准包括附录A在内的全部功能,通过了所有测试矢量. 相似文献
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简要分析DBD型臭氧发生器逆变电源的工作原理,在对PDM调功原理与实现方法的分析的基础上,针对其调功方式的优点和缺点,提出了一种PDM和PWM的混合调功策略.通过对拓扑结构功率输出单元工作过程和功率输出周期工作过程的分析,得到了多频臭氧发生电源的功率调节规则,并通过仿真对其进行了验证. 相似文献
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Kunihiko Koike Shingo Ichimura Akira Kurokawa Ken Nakamura 《Journal of Electronic Materials》2002,31(2):108-112
We have investigated the characteristics of silicon oxidation by concentrated ozone gas through the comparison of the oxidation
by oxygen molecules. A sophisticated high-concentration ozone generator, which exploits the ozone/oxygen gas separation technique
with silica gel, has been developed for the study. The generator can continuously supply ozone-oxygen mixtures with ozone
concentrations up to 30 at.% at one atmospheric pressure. Ozone gas with a concentration of 25 at.% from the generator formed
SiO2 films as thick as 2 nm and 6 nm on Si for a 30 min. exposure at 200°C and 600°C, respectively. On the other hand, oxygen
gas by itself could form SiO2 films with only 1 nm and 3 nm thickness, respectively, at the same conditions. Moreover, in the oxide film formation at 600°C,
the oxide film growth by ozone was proceeded with an oxidation time in excess of 240 min., while it saturated within very
short time in the oxidation by oxygen. These phenomena verify the strong oxidation power of ozone. In addition, we confirmed
that the growth rate of the silicon oxide with ozone dramatically changed when the substrate temperature was over 500°C, and
this suggested the change of oxidation mechanism at this point. However, such a characteristic was not found in oxidation
with oxygen. 相似文献
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全固态PDM发射机因其操作简便、保护功能齐全、质量稳定可靠、效率高等优势,逐渐淘汰了效率低下、能耗偏高的大功率电子管。主要介绍全固态PDM 1 kW发射机和调制高频功率放大器的技术原理,并结合常见案例,提出故障处理需要注意的要点。 相似文献
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P. Asvestas G.K. Matsopoulos K.S. Nikita 《Journal of Visual Communication and Image Representation》1998,9(4):392-400
Fractal dimension has been used for texture analysis as it is highly correlated with the human perception of surface roughness. Several methods have been proposed for the estimation of the fractal dimension of an image. One of the most popular is via its power spectrum density, provided that it is modeled as a fractional Brownian function. In this paper, a new method, called the power differentiation method (PDM), for estimating the fractal dimension of a two-variable signal from its power spectrum density is presented. The method is first applied to noise-free data of known fractal dimension. It is also tested with noise-corrupted and quantized data. Particularly, in the case of noise-corrupted data, the modified power differentiation method (MPDM) is developed, resulting in more accurate estimation of the fractal dimension. The results obtained by the PDM and the MPDM are compared directly to those obtained using four other well-known methods of fractal dimension. Finally, preliminary results for the classification of ultrasonic liver images, obtained by applying the new method, are presented. 相似文献
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Junghan Lee Tino Copani Terry Mayhugh Jr. Bhaskar Aravind Sayfe Kiaei Bertan Bakkaloglu 《Analog Integrated Circuits and Signal Processing》2012,72(1):173-186
Pulse density modulation (PDM) based class-D amplifiers can reduce non-linearity and tonal content due to carrier signal in pulse width modulation based amplifiers. However, their low-voltage analog implementations also require a linear loop filter and a quantizer. A PDM based class-D audio amplifier using a frequency-domain quantization is presented. The digital intensive frequency-domain approach achieves high linearity under low supply regimes. An analog comparator and a single-bit quantizer are replaced with a current controlled oscillator (ICO) based frequency discriminator. By using the ICO as a phase integrator, a third-order noise shaping is achieved using only two analog integrators. A single-loop, single-bit, class-D audio amplifier is presented with an H-bridge switching power stage, which is designed and fabricated on a 0.18???m CMOS process with 6 layers of metal achieving a total harmonic distortion plus noise (THD+N) of 0.065% and a peak power efficiency of 80% while driving a 4-?? loudspeaker load. The amplifier can deliver the output power of 280 mW. 相似文献
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周友芝 《光纤与电缆及其应用技术》2011,(5):22-25
风力发电变桨电机用动力软电缆是中央变桨控制柜与变桨电机之间的动力电源线,其安装在风力发电机的轮毂内。详细介绍了风力发电变桨电机用动力软电缆的应用场合和使用要求、产品结构设计和选材、生产工艺流程,并与国外同类产品进行了比较。所研制的变桨电机用动力软电缆在1.5Mw变桨风力发电机组的变桨自动控制系统中使用了一年多,运行稳定可靠。 相似文献
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介绍了用AT89C51作为控制器核心,对电冰箱的工作过程进行控制,采用臭氧发生器专用集成电路TWH9221组成电冰箱的异味消除电路。并给出了控制程序流程图。 相似文献
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由于臭氧(O2)的独特性质使得它在社会发展中的应用得到越来越多的重视,但是由于臭氧合成效率低,人们一直在寻求高效的臭氧合成方法和装置.在众多臭氧合成方法中,介质阻挡放电法因其结构简单、成本低廉一直为大规模工业臭氧合成的主要方法.这篇论文对平板型介质阻挡放电臭氧发生器的实验过程及结果进行了陈述和理论分析,在本实验室的条件下对影响臭氧产量和浓度的主要因素,诸如气隙宽度、电源电压和频率以及介质层厚度,进行了实验研究,得出最佳的工作条件为;气隙宽度为1.7mm,电源电压为7.5kV,电源频率为38kHz,介质层厚度为1.5mm。 相似文献