Implementation of an Underwater Acoustic Mobile Modem Based on the Direct Sequence Spread Spectrum Scheme 


Vol. 47,  No. 8, pp. 1170-1184, Aug.  2022
10.7840/kics.2022.47.8.1170


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  Abstract

In this paper, we describe the implementation of an underwater acoustic mobile modem based on direct sequence spread spectrum scheme using a bandwidth of about 2.1kHz at a carrier frequency of 6.25kHz and spreading to 16 chip symbols per symbol with a channel symbol rate of about 97.6 symbol/sec. The implemented underwater acoustic mobile modem uses DQPSK modulation to simplify signal processing in the receiver. In addition, in order to respond to a change in the movement speed of the modem within one packet, one packet is divided into 20 sub-frames and transmitted, and the receiver estimates the Doppler shift for each sub-frame and compensates for the Doppler shift for each sub-frame. The effective information data transmission speed of the implemented modem is about 82.5bps when using the Turbo code with a code rate of 1/2, and about 109.8bps when using the Turbo code with a code rate of 2/3. The implemented modem is well operates at a moving speed of up to 18m/s using a channel simulator, and it is successfully received data at a distance of 5km in the shallow water when an other implemented modem transmits data with the 1/10 of the normal output amplitude. The implemented modem will be used for the purpose of delivering a short message in a long-distance mobile environment.

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  Cite this article

[IEEE Style]

S. Kim, S. Kim, H. Baek, "Implementation of an Underwater Acoustic Mobile Modem Based on the Direct Sequence Spread Spectrum Scheme," The Journal of Korean Institute of Communications and Information Sciences, vol. 47, no. 8, pp. 1170-1184, 2022. DOI: 10.7840/kics.2022.47.8.1170.

[ACM Style]

Seung-Geun Kim, Sea-Moon Kim, and Hyuk Baek. 2022. Implementation of an Underwater Acoustic Mobile Modem Based on the Direct Sequence Spread Spectrum Scheme. The Journal of Korean Institute of Communications and Information Sciences, 47, 8, (2022), 1170-1184. DOI: 10.7840/kics.2022.47.8.1170.

[KICS Style]

Seung-Geun Kim, Sea-Moon Kim, Hyuk Baek, "Implementation of an Underwater Acoustic Mobile Modem Based on the Direct Sequence Spread Spectrum Scheme," The Journal of Korean Institute of Communications and Information Sciences, vol. 47, no. 8, pp. 1170-1184, 8. 2022. (https://doi.org/10.7840/kics.2022.47.8.1170)

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pISSN : 1226 - 4717
eISSN : 2287 - 3880