最新刊期
      卷 ， 期 2 ， 1989
      • Tian Liren
        Issue 2, Pages: 1-10(1989) DOI: 10.13756/j.gtxyj.1989.02.001
        摘要：In this paper, analyses have been made on several foreign supervisory systems, then, based on the state-of-the-art of the technologies in China, the appropriate design schemes for system structure, transmission medium and communication mode arc suggested.  
          
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      • Issue 2, Pages: 11-20(1989) DOI: 10.13756/j.gtxyj.1989.02.002
        摘要：<正> 六、对激光管的要求为了相干光纤通信真正能够实用,发送信号的光源和接收端作为本振的光源必须使用半导体激光管,不能考虑暂时方便而借用气体激光器。具体地说,在单模光纤1.55μm实现相干通信,必须使用InGaAsP材料、DC PBH结构,加上DFB或ECL的单频激光管,频率高度稳定、波谱高度纯洁、不随温度变化、不受高码速调制的影响,还要线宽窄和可调谐。半导体激光管的相位噪声是影响相干光纤通信性能的重要因素,它有明确的频率特性,如图13（a）所示。大约在频率1 MHz以下,噪声的谱密度是与1/f至1/f2成比例。在此  
          
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      • Lu Rongchun
        Issue 2, Pages: 21-27(1989) DOI: 10.13756/j.gtxyj.1989.02.003
        摘要：This paper introduces a PFM repeater for fiber transmission of one colour TV signal. After a brief description of the working principle of the repeater, the performance indexes of the transmission of video signal and their measurements are discussed. Results show that these performances have come up to the main indexes prescribed in Technical Criteria of Short Distance Fiber Cable Transmission of TV Programme.  
          
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      • He Yan
        Issue 2, Pages: 28-34(1989) DOI: 10.13756/j.gtxyj.1989.02.004
        摘要：By combining LSI with computers, an intelligent phase-locked loop using digital processing （DP-PLL） can be created. It features a excellent performance of synchronization by a stored program control, and it is an ideal component for network synchronization, because it is able to suppress the ex（?）remely low frequency jittering and can tolerate disturbances of input signal. This paper mainly describes the structure and the design method of the DPPLL. The results of the experiment and the test of the DP-PPL are also presented.  
          
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      • Zhang Zhibing
        Issue 2, Pages: 35-42(1989) DOI: 10.13756/j.gtxyj.1989.02.005
        摘要：The conjugate gradient algorithm for displacement estimation is presented based on the algorithms of Netravali and Robbins and other recursive algorithms. The theoretical and experimental results show that the convergence of the new algorithm has been considerably improved comparing with that of Netravali and Robbins.  
          
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      • Zhang Keli Qing Zhudian Xia Youlang Yuan Qihua
        Issue 2, Pages: 43-46(1989) DOI: 10.13756/j.gtxyj.1989.02.006
        摘要：AlF3 is used as dopant for controlling the refractive index of fluoride glass. Preforms with waveguide structure have been formed by using a built -in casting method.  
          
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      • Huang Shouping
        Issue 2, Pages: 47-50(1989) DOI: 10.13756/j.gtxyj.1989.02.007
        摘要：In this paper, a proper way for the designing of segmented-core fiber with a triangularly profiled inner core has been found out by analysing the influence of the refractive index profile parameters on the fiber characteristics. In this way, the satisfied values of the cutoff wavelength, the dispersion and the field radius of the fiber can be obtained.  
          
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      • Su Chao Yang Zhuang Huang Shouhua
        Issue 2, Pages: 51-53(1989) DOI: 10.13756/j.gtxyj.1989.02.008
        摘要：An experiment by means of low-loss single mode fiber at 1.55μm has been conducted. The LD was modulated by 1.12 Gb/s PRBS. It provides an experimental basis for extra large-capacity communication system.  
          
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      • Su Chao
        Issue 2, Pages: 54-60(1989) DOI: 10.13756/j.gtxyj.1989.02.009
        摘要：In this paper, the dynamic spectrum of DSM-LD under ultra-high rate modulation is discussed, especially for small signal modulation At the same time, the occurrence of Chirp effect is discussed and some measures are considered in order to reduce the Chirp noise.  
          
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