Thailand is located in the subtropical zone and thus the atmospheric temperature is always high through a year. Tropospheric scintillation has been often observed. Ionospheric disturbance may occur because Bangkok is located near the geomagnetic equator. In March and September, the occurrence of ionospheric scintillation has increased as compared with other months. Between the standard deviation and the average value of the scintillation, very good correlation has been observed. We will report the results from the analyzed various properties.
To realize the telecommunication infrastructure needed to support the movement from N-ISDN to B-ISDN, one critical element is the development of a cost effective, flexible fiber-optic subscriber network system. Its chief attribute must be the economical support of multiple services by one optical fiber, as well as rapid response to service orders. This paper describes the current approach to lead a fiber-optic subscriber systems, and also presents a trial in Yokosuka VI&P experiments.
For HDTV bit-serial digital interface, it is necessary to transport digital data stream in very high bit rate. We have developed equalization system to equalize high bit rate digital signal (1.485 Gbps) transported by coaxial cable. We have also developed automatic equalization system for various cable length.
Described is an RF signal transmission system for the TV relay station by using a wide band optical modulator which can modulate its optical power by RF signals from the recieving antenna. This system is very effective to prevent damages by lightning at TV relay stations since optical fibers can be used for the circuit between the recieving station and the transmitting station. In addition, use of this system can improve reliability and maintenance work as well as reducing construction cost because only passive circuits are used at the recieving station.
In case of using a large-sized crane near a high power medium wave transmitting station, high-frequency voltages and currents are induced by electromagnetic induction, which can be dangerous to workers. We have developed a equipment for reducing electromagnetic induction at the hook of a crane. Use of a ferrite toroidal core has attenuated the high-frequency energy to human bodies by making use of thermal losses of the core and high impedace part coupled with a parallel resonance clrciut.