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

1. Ku波段信号的传播特性东京工业大学用直径1.8米的天线接收了JCSAT卫星12 GHz的遥测信号。接收信号电平和降雨率，这是使用附近的天线雨量计测量不断重试。获得了1998年10月至2001年9月3年的实测雨衰减和降雨率的累积时间分布。经验证，实测值与ITU-R方法预测值吻合较好.利用卫星系统进行计算机通信本文推导了在由VSAT卫星系统和地面Internet链路组成的非对称网络上，用TCP传输文件和用HTTP传输WWW数据所需的传输时间和吞吐量的理论公式。实验结果是在广岛市立大学和东京工业大学之间建造的上述不对称上获得的。将公式计算结果与实验结果进行了比较，两者吻合较好。3.远程教学系统利用VSAT系统在日本东京工业大学和广岛城市大学之间实现了具有可视主持人的视频会议系统。双方进行了四次约1小时的互动讲座。通过问卷调查的方式抽取参与者的有效性和存在的问题进行分析.微波在医学上的应用：研究了医用介质材料的测温特性、微波热疗、龋齿诊断等方面的应用。

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.