Acoustic video-signal transmission system for autonomous underwater vehicle

This paper describes the acoustic video-signal transmission system for an autonomous underwater vehicle. The acoustic transmission system can transmit a color image of 160/spl times/120 pixels per one second over 1600 meters in distance. The size and weight of the electronics are very small and light enough to be put in a small AUV. The power consumption, that is less than 20 watts, is small enough for AUVs. The transmission speed is 16,000 BPS. In order to realize this system, quadrature phase-shift-keying, adaptive equalizer, image compression, and error correction code for error free transmissions are employed. A wideband transducer was developed for high-speed transmission. It has a small size, light weight, and high sensitivity. A vertical transmission test was carried out in a depth of 100 meters. As a result of this test, it was found that this system has enough Doppler immunity and can transmit images more than 1600 meters in distance without any errors if the SNR (signal to noise ratio) is greater than 15 dB. In the sea test of our AUV, the images of the sea floor were successfully transmitted. This test was carried out at a depth of 400 meters, and no transmission errors were detected.