Abstract
Verification about adaptability of an underground wireless communication system applying low frequency electro-magnetic wave, which has been developed for improving the efficiency during installation of transducers and stability of measurement, was carried out by monitoring test of pore water pressure at the existing rock fill dams. But, after five and half years, these were out of order and not able to perform data communication. The authors examined the reason they were out of order from the capacity test of their batteries and voltage data of batteries measured in site. From these results, it was clarified that capacity of its battery was sufficient but the voltage descent happened when the high electric current was required, for example, in a data communication procedure. Then the batteries were set in parallel to moderate the effect of voltage decent. Improved transducers were able to reduce the effect of voltage decent comparing with test models and perform correctly during six years after installed. Then it was verified the long term performance of a wireless transducer working by inner batteries depended on not only capacity of batteries but also voltage decent of them.
