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**Ocean Acoustic Data Transmission System for Seabed Experiment**

Proposal for acoustic data acquisition and transmission system. Includes storage, compression, and networking infrastructure for underwater experiments in East-Sicily. Utilizes high-speed internet, radio links, and data servers for efficient data transfer and analysis.

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**Ocean Acoustic Data Transmission System for Seabed Experiment**

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  1. Giorgio Riccobene, INFN-LNS LIDO 2nd Meeting

  2. Acoustics at LIDO East-Sicily TSS OFF-SHORE ON-SHORE Hydrophones + preamplifiers Digital audio data + GPS time TCP/IP Audio Data ADC (192kHz/24 bit) FCMb off-shore local internet network FCMb on-shore ADS (Acoustic Data Server) ADC (192kHz/24 bit) Data acquisition board ADC (96kHz/24 bit)

  3. The INFN-LNS Shore Lab infrastructure in Catania The Shore laboratory is equipped with workshops, a large structures construction hall, a data acquisition hall a computing room. A 32 Mbps radio link is available to transmit data from the Shore Lab to the Laboratori Nazionali del Sud (LNS-INFN) of Catania, i.e. one of the 4 major laboratores of INFN in Italy. LNS is directly connected to the high speed ethernet link EumedConnect and to the main Italian Internet infrastructure for research (GARR)

  4. Data acquisition and transmission proposal STORAGE STORAGE Client CIBRA /LNS Client UPC Public Data Storage Streaming server MADS (private) CTSL Undersea experiment ADS Acoustic Data Server PADS LNS RADS LNS Wireless Bridge

  5. Data acquisition and transmission proposal Constraints: Radio Link CTSL – LNS  26 Mbps 2 Mbps for standard communications 24 Mbps left for LIDO LIDO payload 24 bits x 96 kHz x 4 Ch = 8 Mbps TSN acoustics + Geophysics data 32 bits x 192 kHz x 4 Ch = 22 Mbps TSS acoustics External accesses for monitoring and controls 2 Mbps We need a storage and compression Unit at CTSL

  6. LNS networking architecture GARR Internet LNS Wireless Bridge LNS Firewall DNS WEB Router MAIL DMZ LNS-LAN 172.16.X.X Media Converter Filtering Bridge Metropolitan Area Network CTSL University of Catania CTSL- LAN

  7. Data acquisition and transmission proposal

  8. LNS networking architecture News from INFN Computing and Networking Committee: The LNS has 1 GBit connection to the fast interntet infrastructure. News from the Italian Networking Infrastructure for the Research (GARR): A 2.5 Gbit link to Catania Univ. Campus is foreseen in 2011.

  9. The DAQ scheme at CTSL: ADS Data from deep sea will be acquired by a machine called Acoustic Data Server (ADS) that will receive the raw data stream and will make it available on the CTSL Local Area Network. The ADS will be equipped with a dedicated board (at the moment an RME AES32) capable to sustain the underwater hydrophones data stream. Then, data will be checked and sent to clients using TCP-IP protocol. Sample data format for LIDO TSS: HEADER Time in units of us (from the GPS on shore) Sampling frequency (192000 Hz) Number of frames of the acquired AES packet (192 if no frame is lost) Number of Channels Channel ID(S) Data Frame 1: Channel 1 (24 bits)| Channel 2 | Channel 3 | Channel 4 Data Frame 2: Channel 1 (24 bits)| Channel 2 | Channel 3 | Channel 4 …. Data Frame 192: Channel 1 (24 bits)| Channel 2| Channel 3 | Channel 4

  10. The DAQ scheme at CTSL: ADS Data sent from the ADS will be analysed on-line by another PC that performs: On-line data visualisation: e.g. amplitude vs. time and compact spectrogram for the 4 channels Summary information recorder (“recording info file”): e.g. average, maximum and percentiles of Sound Pressure Density in a given time period (eg. for a 15’-or shorter- time slices, according to the length of the raw hydrophone data file). To be decided by the Acoustic Noise and Source Tracking W.G. These data will be uploaded to the RADS and will represent an info file for the recorded raw hydrophone data file.

  11. The DAQ scheme at CTSL: RADS The Raw Acoustic Data Storage will be controlled by a dedicated PC that will recover raw data from the local CTSL internet, re-arrange them and record them on audio files (standard format such as .wav or BVF). The given the data rate should allow file recording for 15’(or max 20’) time length corresponding to approx 1.5 GB single file size on disk. Recorded file will be compressed (several audio file compression algorithms are under test at CIBRA-Pavia) and will be stored on the RADS. A preliminary estimate on these algorithms gives 75% compression ratio for standard wav files. This gives about 50 GB/day of required audio data storage. RADS will act as a large circular buffer storage unit. Data on RADS will be acquired, compressed, transferred to LNS (MADS) and deleted. The requested disk size of RADS is of the order of 1 TB to allow data storage redundancy and possibility of local backup in case of radio link failures for long time periods. Continuous transfer of compressed audio files to the Main Acoustic Data Storage unit at LNS is then possible: 500 MB every 15’ leads to a requested link speed of 3.5 Mbps for the file data transfer. A minimal fraction of the band will be used to transfer the associated “recording info file” that allows fast previews of acquired data.

  12. The DAQ scheme at CTSL: RADS CIBRA is presently testing different algorithms, the best one seems to be FLAC FLAC stands for Free Lossless Audio Codec; it is a lossless compressor, meaning that audio is compressed in FLAC without any loss in quality. Something like winzip but optimized to work on digital audio signals in any of the Microsoft supported formats, including 24 bits and multichannel. Main requisite is a file header structured according exactly to MS WAVE_FORMAT_EXTENSIBLE rules. http://flac.sourceforge.net/documentation_tasks.htmlTests carried out using the NEMO files (2 Channels reduced from 24 to 16 bits) shown a reduction of 90% file size

  13. The DAQ scheme at LNS: MADS The Main Acoustic Data Storage will have a dedicated link to CTSL and it will continuously download the compressed data files and store them (together with the associated “info file”) on disks. MADS will be the main data repository of the experiment (i.e. also for the geophysics data). Access to the MADS will be restricted to dedicated machines of the LIDO partners. The total disk size is expected to be approx 20 TB (for a year) for acoustic raw data files (compressed) plus a 20 TB backup unit. The LNS Computer Centre will also take care of MADS software/hardware maintenance.

  14. A Fiber channel cabinet for the MADS NetApp FAS2040 A fiber Channel HD cabinet Permits fast data Reading writing from internet access

  15. The DAQ scheme at LNS: Web and streaming General Public Acoustic Data Server and Storage This server will run public outreach applications. This machine will be placed on the DMZ (De-Militarized Zone) of LNS network to permit general public access (via web, streaming etc.) to selected files or raw data.

  16. The GPS system To be discussed with Tecnomare and INGV

  17. Open questions from the last meeting Agreement on Data Acquisition/distribution architecture Quantify the data to be saved, i.e. Quantify disk space. Software : Automatic download procedures (Tested) Data format protocol in the final stage... Costs: Servers and disks Run shifts or automatic procedure ? (external collaborators ??) Main science results and test (develop) dedicated software Define software test procedures Agreement with external Institutions ? Alert to Military / Institutes/ Volunteers

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