抄録
Resolution in time difference between signals in separate channels of a cassette recorder for an ocean bottom seismograph is investigated. The small-size recorder utilizing compact cassette tapes has been developed especially for ocean bottom seismographs since 1971. Compact cassette recorder is better than open reel tape-recorder regarding size, cost, proof against shock, electric power consumption, and so forth. However, for maintaining required quality of observation at sea bottom, cassette-type recorders demand careful adjustments. It is because thin cassette tapes are very sensitive to the state of tape path and tape transport mechanism. Unstability of tape transportation extremely increases amplitude modulation noises in recorded signals and phase distortion between channels.
In the present paper, the following elements which are important for stable tape transportation are studied; (1) relative position of a cassette half to a pinch-roller and heads, (2) alignment of tape guide, head, capstan and pinch-roller, (3) tension of driving, belt, (4) parallelism of pinch roller axis to capstan.
When all these key factors which control the quality of recording are satisfied, the error in time resulted from recording and reproducing process is reduced less than 1/125sec.
