2019_programme: HIGH-RATE VERTICAL ACOUSTIC COMMUNICATION FOR IMAGE TRANSMISSION FROM A DEEP SUBMERSIBLE SHINKAI6500



  • Session: 05. Underwater Communications and Networking
    Organiser(s): Tsimenidis Charalampos, Mitchell Paul, Pelekanakis konstantinos
  • Lecture: HIGH-RATE VERTICAL ACOUSTIC COMMUNICATION FOR IMAGE TRANSMISSION FROM A DEEP SUBMERSIBLE SHINKAI6500 [invited]
    Paper ID: 767
    Author(s): Shimura Takuya, Kida Yukihiro, Deguchi Mitsuyasu
    Presenter: Shimura Takuya
    Presentation type: oral
    Abstract: In Japan Agency for Marine-Earth Science and Technology (JAMSTEC), a manned submersible SHINKAI6500 have been operated for deep sea research. Last year, a new uplink communication system was developed for image transmission form the vehicle. The frequency band used for the system is 20 kHz +/- 5 kHz, and the transmitting level is typically 195 dB re 1 μPa and signals are received with a receiver on the bottom of the mothership. The communication signal is modulated with single-carrier modulation of 16 to 128 quadrature amplitude modulation (QAM) at the symbol rate of 10 kS/s. In each packet, 50, 400 and 8192 symbols are assigned for the synchronization, training and information-bearing signals, respectively, and forward error correction (FEC) is not used. Thus, the percentage of the information bearing part is 98.9 %. As a method of channel equalization, a single-channel decision feedback equalizer (DFE) is adopted. This new developed communication system was installed in SHINKAI6500 and its performance tests were carried out in trial cruises diving to the depth of 3,600 m. The performance with the single-channel DFE is compared with that of OFDM in this experiment additionally. As results, the demodulation with the single-channel DFE was very stable and no bit error occurred in most of the packets even under Doppler shift up to 15 Hz caused by the heave motion of the mother ship and ascending/descending motion of the vehicle. In case of 128QAM, the number of bit errors was just 10 bits in the total 700,000 bits transmitted. Thus, it was demonstrated that communication at the data rate of 69.2 kbps (=70*0.989) was achieved stably. In the meantime, demodulation results with OFDM are degraded depending on the Doppler shift, although the techniques of 1/3 pilot interpolation and re-sampling based on the estimated frequency shifts are applied.
  • Corresponding author: Dr Shimura Takuya
    Affiliation: JAMSTEC
    Country: Japan
    e-mail: