14KC音響測深機とそれと同一機構を有する試作極超音波音響測深機による海底記録像の比較(日本航海学会第21回講演会)

概要

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We published that the echo-trace of the sea-bottom obtained by the 200kc echosounder with sharp beam is much more similar to the true shape than that by the lower frequency echo-sounder. We made a 200kc echo-sounder, the sounding range, the recording paper speed and the width of paper of which were the same as those of 14kc echosounder and made an experiment by these two echo-sounders on the sea off Kurihama, Kanagawa Prefecture, on 24th April 1959. We installed the 14kc and 200kc transducers on one side of the ship in order to avoid the change which the echo-traces underwent by the installation. There is no appreciable difference for the even bottom but differences come out as the shape of bottom becomes complicated. In case of 14kc it is often that one cannot measure the depth of the sea-bottom because many false bottoms are recorded on account of the dull beam, but in case of 200kc it is easy to measure the depth of the sea-bottom because nothing but the bottom is recorded and the accuracy of sounding is high on account of the sharp beam. In case of 14kc, the accuracy of sounding might be high if its beam is made as sharp as that of 200kc, but it is not practical because a very large transducer is necessary. A sharp beam is much more easily obtained by the high frequency than by the low one.
社団法人日本航海学会の論文