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111.
根据采油厂油井监控的需求,将油井数据采集、网络视频监控技术和无线通信技术紧密结合起来,设计规划适用于油井的远程智能监控系统。重点介绍了远程智能监控技术的系统原理、组成结构、实现方式及其实际应用效果。 相似文献
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113.
PC作为Profibus-DP单主站的实现 总被引:1,自引:0,他引:1
主要介绍Profibus现场总线的基本特性和通信协议,讨论了以PC作为Profibus—DP单主站实现的可行性,并给出了C语言实现的程序。 相似文献
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Xiaofeng Liao Xueming Li Jun Pen Guanrong Chen 《International Journal of Communication Systems》2004,17(5):437-445
In this paper, a simple image secure communication scheme based on the chaotic Chebyshev map and chaos synchronization is proposed. The scheme relies on the excellent correlation property of chaotic sequences, which is very desirable for secure image communication. The results obtained by computer simulation indicate that the transmitted source image can be correctly and reliably recovered using the proposed scheme, even through a noisy channel. Notably, the scheme possesses relatively high security and can be easily implemented. Moreover, the quality of the recovered image is satisfactory, quantified by such common criteria as the bit‐error rate performance. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
117.
设计了一种结构简单,抗干扰能力极强的计算机通信接口电路。该电路利用模拟开关实现了全数字二态电平(1,0)与三态电平(1,0,-1)之间的相互转换;利用模拟开关导通电阻的动态效应以及MOS晶体管开启电压Vτ的衬偏效应,提高了接收电路的抗干扰能力,提出了一种与共模干扰无关的模拟数字混合接收电路。 相似文献
118.
Claudio Sacchi Gianluca Gera Carlo S. Regazzoni 《International Journal of Satellite Communications and Networking》2004,22(2):193-215
This paper aims at focusing on the aspects concerning the physical layer design for an innovative satellite communication experiment. Such an experiment, denoted by the acronym DAVID–DCE (Data and Video Interactive Distribution—Data Collection Experiment) is based on the exploitation of the W‐band (75–110 GHz) for high‐bit‐rate satellite transmission. The potential advantages of using of the W‐band are mainly related to the great bandwidth availability, and to the absence of interference. Moreover, an expected result of the experiment is a substantive improvement in the communication system's performances in the presence of meteorological phenomena (e.g. rain) as compared with the more conventional Ka‐band satellite transmission. On the other hand, problems to be faced concern the non‐ideal behaviours of hardware devices employed for high‐frequency digital transmission. In particular, carrier recovery and timing recovery are the most crucial signal‐processing tasks to be carefully considered in the design of the physical level of the system, because they considerably suffer from hardware impairments. The purpose of this work is to illustrate the proposed solutions in terms of the most critical modulation, demodulation and synchronization design issues, together with the effects of non‐ideal behaviours of hardware components on BER performances. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
119.
移动通信基站在高层建筑天台架设的定向天线,对周围环境的电磁辐射影响水平的监测进行分析,探讨高层建筑天台电磁辐射环境的污染防治对策。 相似文献
120.
Docherty Nancy M.; Cohen Alex S.; Nienow Tasha M.; Dinzeo Thomas J.; Dangelmaier Ruth E. 《Canadian Metallurgical Quarterly》2003,112(3):469
This study examined the degree to which different types of communication disturbances in the speech of 48 schizophrenia patients and 28 controls were variable and state related versus stable and traitlike. Clinically rated formal thought disorder and 5 types of referential disturbance showed substantial stability within participants over time. The sixth type of referential disturbance, the vague reference, was not stable over time. Formal thought disorder was associated with the severity of core psychotic symptoms in patients, whereas referential disturbances showed little or no association with positive or negative symptom severity. Furthermore, changes in psychotic symptoms over time were accompanied by corresponding changes in formal thought disorder but not referential disturbances. These results support the idea that some types of referential disturbances are traitlike and may be reflective of vulnerability as well as manifest illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献