用通用DSP实现话带MODEM

概述了设计话带ＭＯＤＥＭ时所要考虑的基本问题。介绍了一种用通用ＤＳＰ设计的ＭＯＤＥＭ，并讨论了相应的控制程序和调制，解调程序的设计方法和结构框图，而且设计了一个简单实用的握手协议。最后，进一步分析了这种ＭＯＤＥＭ的特点和它的应用前景。     

话音ATM交换的实现─—ATM论坛电路仿真系列建议

近年来，随着ATM主干网络的建设和发展，研究ATM对现有通信业务的支持方式和适配技术是目前ATM技术研究的热点之一。话音ATM交换在降低话音通信成本和简化网络操作环境等方面提供了大量的技术手段，并且支持在单一网络环境中的多种综合业务传输。ATM论坛制定了电路仿真系列建议，话音ATM交换的技术已经基本成熟。文章通过对话音ATM交换在实现和优化方面的技术进行分析，并提出一种基于NativeModeATM的话音通信方式。     

Evaluation of the Kushida Method of short-term earthquake prediction

Kushida and Kushida found that FM radio waves from stations at distances over-the-horizon are received before earthquakes. Based on this finding, since the mid-1990’s, the Kushidas have been practicing “Earthquake Precursor Detection Experiment”. The performance of the Kushida method during 2000–2003 has been evaluated by checking their predictions against the actual seismicity. During the period, there were 92 Kushida predictions mentioning the possibility of M ≥ 5.5 event, whereas there were 49 M ≥ 5.5 earthquakes in the Japanese region. If the criteria for successful prediction are set as: the errors in date is less than one day, epicentral position is roughly within specified area, and error in M is less than 0.5, the success rate was 20% and the alarm rate was 12%. If we relax the criteria to: the errors in dates within 10 days, epicenter within additional 100 km of specified area and the magnitude error less than 1.0, the success rate was 40% and the alarm rate was 27%. These rates may look insufficient for a practical prediction method. Considering, however, the fact that no other short-term prediction has ever been made in Japan so far it is a significant achievement. Moreover, it was found that in almost all failed predictions, meaningful signals were detected although the interpretations were incorrect. This indicates that the method is promising provided further investigation is carried out. The same evaluation at the M ≥ 6.0 level showed that the general performance was similar to the M ≥ 5.5 level, except that both success rate and alarm rate were lower at the M ≥ 6.0 level. If this unexpected finding is real, it might be inherent to the methodology using scattering of short-wave length radio waves as suggested by M. Hayakawa and may contain important information in understanding the earthquake physics and LAI-coupling. The results of the present study indicate strongly that the earthquake prediction research using anomalous transmission of VHF FM radio waves should be enhanced in parallel with complementary research in other frequency ranges.     

Discrete storage processes and their Poisson flow and fluid flow approximations

Consider discrete storage processes that are modulated by environmental processes. Environmental processes cause interruptions in the input and/or output processes of the discrete storage processes. Due to the difficulties encountered in the exact analysis of such discrete storage systems, often Poisson flow and/or fluid flow models with the same modulating environmental processes are proposed as approximations for these systems. The analysis of Poisson flow and fluid flow models is much easier than that of the discrete storage processes. In this paper we give sufficient conditions under which the content of the discrete storage processes can be bounded by the Poisson flow and the fluid flow models. For example, we show that Poisson flow models and the fluid flow models developed by Kosten (and by Anick, Mitra and Sondhi) can be used to bound the performance of infinite (finite) source packetized voice/data communication systems. We also show that a Poisson flow model and the fluid flow model developed by Mitra can be used to bound the buffer content of a two stage automatic transfer line. The potential use of the bounding techniques presented in this paper, of course, transcends well beyond these examples.Supported in part by NSF grant DMS-9308149.     

标准气体在检测可燃气体报警器中的重要性

介绍可燃气体报警器的检测现状，分析可燃气体报警器检测元件中毒的原因，强调了检测可燃气体报警器时使用标准气体的重要性，以及标准气体的正确使用。     

大功率扬声器与功率有关的若干问题

在大功率扬声器设计中音圈线径设计是关键。从介绍音圈线径与功率的关系开始,谈到最大振幅(位移)及各注意要点,最后介绍了大功率扬声器用胶粘剂的一些使用问题。     

ROK101007蓝牙模块及其在无线火灾自动报警系统中的应用

ROK101007是Ericsson公司生产的一种实现蓝牙功能的中短距离通信模块.从应用的角度出发,将ROK101007作为通信模块集成到无线火灾自动报警系统中,对蓝牙技术在火灾报警中的应用进行了探讨和研究,并给出了火灾自动报警系统原理框图和ROK101007与单片机及上位机的接口电路,及相应的主要软件设计方法.     

语音增强用于坦克驾驶舱内无线语音通信

讨论了一种基于传统谱相减算法的改进方法。利用语音的短时平稳性,通过先验幅度比来连续更新噪声谱的估计,从而代替复杂的VAD(话音活性检测)。计算机仿真结果表明,这种改进方法有效抑制了噪声干扰,语音得到了增强,在极大地提高信噪比的同时,将残留的音乐噪声和语音失真保持在人耳听觉容忍的范围以内,从而较好的保持了语音自然度。     

声音转换技术的研究与进展

声音转换是一项改变说话人声音特征的技术,可以将一人的语音模式转换为与其特性不同的另一人语音模式.声音转换算法的目标是确定一个什么样的模式转换规则,使转换语音保持第一个说话人原有语音信息内容不变,而具有第二个说话人的声音特点.本文介绍了当前声音转换技术领域的研究状态,主要分析现有声音转换技术中各种转换算法的实现原理,描述声音转换系统性能的各种评估方法,最后给出了对声音转换技术的简要评述和展望.