HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
GESMA's (Groupe d'Etudes Sous-Marines de l'Atlantique) objective is to develop a sufficiently robust acoustic link allowing the transmission of different data (text, images, etc.). Implementation of the acoustic link has led the ENST Bretagne to develop a real-time platform called TRIDENT (TRansmission d'Images et de Données EN Temps réel). To reduce the various perturbations caused by the underwater acoustic channel (UWA), a blind spatio-temporal equalizer is used. The acoustic link performance was evaluated and has shown its robustness for transmission over a strongly disturbed channel. GESMA also wants to increase the link reliability and provide a strongly protected low bit rate speech (MELP, 2400 bit/s) transmission. In order to do so, channel coding will be added to the system. Different kinds of error correcting schemes will be tested including convolutional codes (CC) and Reed Solomon (RS) block codes.
In 1997 GESMA (Groupe d'Etudes Sous-Marines de l'Atlantique), in collaboration with TELECOM Bretagne, launched a new project, called TRIDENT. First objectives were to develop a multiple rate underwater acoustic link for images, text and data transmission. This link was designed to provide a wireless communication to AUVs. Since 2006, the platform was extended to low bit rate speech transmission using a MELP coder working at 2400 bps. Such a rate allows to use lower carrier frequencies, able to reach longer ranges in the case of speech transmissions. More recently two channel coding options were added to the TRIDENT platform. Convolutionnal codes (CC) and Reed Solomon (RS) block codes were then checked. These simple codes were not able to improve significantly the Bit Error Rate (BER) at the channel decoding output. That is why, GESMA decided to introduce the turbo codes options and more precisely the Reed Solomon Block Turbo Codes (RS BTC) to enhance the channel decoding efficiency. The data transmitted are interleaved and frame recovery is performed in reception. After system validation in static condition, in Brest Penfeld river (November 2009), sea trials have been recently conducted in Brest bay (March 22 to 26, 2010) in moving condition. This paper presents the different possibilities offered by the platform for images and speech transmissions and the RS BTC channel coding options.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.