A set of 1023 digit m-sequence codes for acoustic tomography
Akio Kaya (Oki Electric Industry), Toshiaki Nakamura, Tomoyuki Kanaizumi, Hidetoshi Fujimori and lwao Nakano (JAMSTEC)
New acoustic tomography experiment was just started on Dec. 1998 for observation of the temperature and the weak but large-scale of water-circulation in the central equatorial region (0.8-14.3｡?, 177.7｡?-172.05｡?) by deploying 5-acoustic transceivers. To keep high accuracy, short time valiance on the reciprocal travel time of acoustic rays between each transceiver is reduced by the transmission of signal at same time on each transceiver. Our system used PSK signal modulated by a 1023 digit m-sequence code. On the locations of the transceiver in this experiment, some transceivers receive signals with overlap in time from different transceivers, which have almost same travel time. To distinguish with each other, each transceiver has different code but same number of digit. The correlation results of the replica and overlap signal will be discussed in the presentation on Symposium.
