Abs 重 ract Remotely operated vehicle ( ROV ) is a useful tool in underwater investigation . However , the guidance of ROV to a target is a very difficu 工 t task without the assistance of a locating system . We , therefore , tried to develop a locating system for the ROV which displays , in Ieal time , both the locations of a ROV and a target by the use of multiple piIlgers ( ultrasonlc fish tag ) of a single frequency attached to them . From a practical point of view , the authors adopted a

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... of time division scheme in order to distinguish each pinger . The syste エ n consists of four hydrophones , a four channel − receiver , and a personal computer . As the signal is received , it interrupts ontQ a personal computer so that the signal can be processed . When three pulses of an interval are found in the received pulse train, a corresponding pinger can be ident三fied. Tracking of the pinger can be performed by the prediction of the next receiving time Qf the pulse using both the phase difference and the pulse interva1. The same is to be applied to other pingers . In this system , the pinger position is calculated by the method of hyperbolic line of position calculation . In the experiments , the guidance of ROV to the target pinger was achieved witll ease , and each pinger was distinguished successfully ,