Title :
Toward a digital acoustic underwater phone
Author :
Goalic, A. ; Labat, J. ; Trubuil, J. ; Saoudi, S. ; Rioualen, D.
Author_Institution :
Dept. Signal et Commun., Ecole Nat. Superieure des Telecommun. de Bretagne, Brest, France
Abstract :
The paper deals with the design of a digital acoustic underwater phone prototype. Digital techniques allow to achieve a synthesized speech with a quality close to the telephonic one. The input speech signal is compressed down to 5.45 kbit/s using a CELP coder. The bit rate is 6 kbit/s before channel coding and expected to be about 8 kbits/s after channel coding. A QPSK modulation with differential encoding was chosen to transmit the useful signal. For the receiver the authors use a scheme where synchronization and equalization (FSE+DFE) were jointly optimized. The whole system (unidirectional link) has been implemented on single DSPs (Motorola 56001) and tested successfully in a very difficult environment (IFREMER pool)
Keywords :
acoustic receivers; channel coding; data compression; decision feedback equalisers; digital communication; linear predictive coding; quadrature phase shift keying; speech codecs; synchronisation; telephone sets; telephony; transmitters; underwater sound; 5.45 to 8 kbit/s; CELP coder; Motorola 56001; QPSK modulation; bit rate; channel coding; differential encoding; digital acoustic underwater phone; equalization; input speech signal; synchronization; synthesized speech; unidirectional link; Channel coding; Decoding; Digital signal processing; Prototypes; Quadrature phase shift keying; Signal synthesis; Speech coding; Speech synthesis; Transmitters; Underwater acoustics;
Conference_Titel :
OCEANS '94. 'Oceans Engineering for Today's Technology and Tomorrow's Preservation.' Proceedings
Conference_Location :
Brest
Print_ISBN :
0-7803-2056-5
DOI :
10.1109/OCEANS.1994.364247
