With a view to providing paramedical care within moving vehicles, a telemedicine technique using mobile satellite communication was proposed. With this technique, the diagnosis from a specialist and the emergency care under his/her instructions would be available on the spot without unnecessary delay. The characteristic problems of this technique were identified as: channel capacity, size of the system, reliability of vital sign transmission, real-time operation and electromagnetic interference. Measures against these problems were devised, and their effectiveness was analyzed. A data format was designed and an experimental system was developed. The system can simultaneously transmit a color image, an audio signal, 3 channels ECG and blood pressures from a mobile station to a ground station. It can transmit an audio signal and error control signals from a ground station to a mobile station in a full duplex mode. Fundamental transmission characteristics were measured in a fixed station. Finally, experiments of medical data transmission were conducted with a navigating ship and an aircraft flying an international route. The measured threshold values of C/N(o) to guarantee satisfactory data reception were well below the lower boundary of C/N(o) of the communication link. Consequently, the feasibility of this technique was verified.
MIURAAbstruct-The Japanese domestic experimental mobile satellite system (EMSS) has been studied to establish high qnality channels for small vessels with compact and low-gain antennas. The present international maritime satellite communication system (INMARSAT) has also been studied for the next generation to extend services for small ships, for which the present ship terminals inclnding the antenna systems are too large and too heavy. By using a low-gain antenna, however, mdtipath fading caused by sea reflections wiU become a serious problem in designing the new system. To take effective countermeasures to the fading effect, it is verg important to get a better knowledge of the fading phenomena caused by sea reflections.From a standpoint of maritime satellite communications, experiments measuring the amount of fading were performed nuder various sea conditions and in two frequency bands. The wave height, which is considered the most important experimental parameter, was measured objectively by a wave rider buoy. The experimental results show that the amonnt of fading depends on a wave height and radio frequency and, as the most interesting result, as a wave increases above a certain level, the amount of fading decreases. These results are also discussed theoretically.
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