PN 신호열을 이용한 수중음향 실해역 채널 측정 방법 및 결과

Abstract

In this paper, the measuring method of delay profile characteristic of underwater acoustic channel in the shallow water using the auto-correlation characteristic of PN (Pseudo-Noise) sequence is described. For measuring the underwater acoustic channel characteristic, two PN sequences are used as a transmitted data of I-channel and Q-channel of QPSK symbol and QPSK signal is transmitted with symbol rate of 5kHz and carrier frequency of 25kHz carrier. In the receiver, the received signal is sampled at 200 kHz and stored in the memory. The channel delay profile is computed via computing the correlation of received data and transmitted QPSK symbol sequences over one period of PN sequence used as a transmitted data. The authors acquire the channel data for 675m and 1429m propagation distances paths, and analyze the delay profile of each channel cases. For 675m distance case, the delay profile spans about 30ms and there are three paths, having relatively high energy, within 1ms delay time difference. For 1429m distance case, the delay profile spans about 2ms and there are 3 paths.