Research on multi-points multimedia apprications using VSAT satellite communication system

1.日本东京工业大学采用直径1.8 m的天线接收来自JCSAT卫星的12ghz遥测信号。在天线附近用雨量计测得的接收信号电平和雨率不断重复。得到1998年10月至2001年9月3年雨量衰减和雨量的累积时间分布。结果表明，ITU-R方法的实测值与预测值吻合较好。在由VSAT卫星系统和地面互联网链路组成的非对称网络中，推导了采用TCP协议传输文件和HTTP协议传输WWW数据所需的传输时间和吞吐量的理论公式。对广岛市立大学和东京工业大学之间构建的上述不对称结构进行了实验研究。将公式计算结果与实验结果进行了比较，两者吻合较好。远程学习系统广岛市立大学和东京工业大学之间使用VSAT系统实现了带有可视演示者的视频会议系统。双方进行了四次互动式讲座，每次约1小时。通过问卷调查的方式对参与调查的人员进行问卷调查，并对其有效性和存在的问题进行分析。微波的医学应用。对医用介质材料、热疗材料、蛀牙诊断用微波测量温度特性进行了研究。

1.Propagation characteristics of Ku fand signalThe telemetry signal at 12 GHz from JCSAT satellite was received using 1.8 m diameter antenna at Tokyo University of Technology. Received signal level and rain rate which was measured using raingauge near the antenna were continuously retried. Cumulative time distribution of measured rain attenuation and rain rate were obtained for 3 year from Oct. 1998 to Sept 2001. It was confirmed that the measured value and predicted value by the ITU-R method are well coincide with each other.2. Computer communication using satellite systemThe theoretical formula, which evaluate transfer time and throughput required for the file transfer using TCP and for the WWW data using HTTP, are derived over the asymmetric networks composed of VSAT satellite system and terrestrial internet link. Experimental results were obtained on the above mentioned asymmetric which were constructed between Hiroshima City University and Tokyo University of Technology. Calculated results by the formula and experimentally obtained results were compared and these two results were well conformed.3.Distant learning systemVideo conference systems with visual presenter were implemental between Hiroshima City University and Tokyo University of Technology using VSAT systems. Interactive lectures of about 1 hour were carried out from both side four times. Its effectiveness and problems were extracted by questionnaire from the participants and analyzed.4. Medical application of Micro waves.Research on the measurement temperature characteristics of dielectric material for medical use, thermotherapy, diagnosis of decayed tooth using micro waves were carried out.