Research On The Key Technologies Of Data Acquisition And Transmission In Hydrophone Linear Array

Hydrophone linear array is a type of acoustic sensing array which has a broadapplication prospects in the field of ocean exploration, and can be used to achieve thetime and space domain equally acoustic information acquisition underwater, as animportant dual-use technology in marine areas. This paper focused on the commonkey technologies for active and passive underwater acoustic detection modes,including multi-channel piezoelectric hydrophones signal conditioning and dataacquisition, cascaded digital base-band channel data transmission of fiber-opticinterferometric and piezoelectric hydrophones, the real-time data-sequence-filestorage and waveform echo technology in shipboard master workstation. Meanwhile,we designed dedicated distributed array data acquisition clock synchronization system,explored Turbo coding technology used in cascade channel, and two different type ofpractical linear array streamer for really explorations.The main content and completion of the work as follows:1. Designed and implemented a common type hydrophone line array dataacquisition and transmission system, which can support both active and passiveacoustic detection, The system includes variable-gain signal conditioning formulti-channel piezoelectric hydrophones and multi-channel synchronoushigh-resolution analog-to-digital conversions, underwater circuit node’s local dataframing and cascaded uploading, underwater distributed power supply network, theshipboard master workstation data interface based on the PCI interface and mastersoftware component.2. Proposed and implemented a master-slave data acquisition clocksynchronization method based on the simplification and improvement of IEEE1588precision clock synchronization protocol. Established a data acquisitionsynchronization clock transfer model for full array, determined the clock transmissionerror compensation method by experiments, and achieved a full-arraysub-microsecond-level data acquisition clock synchronization.3. Studied the Turbo channel coding and decoding system for the applicationtarget of hydrophone line array cascade channel, analyzed Turbo codes performancethrough computer-aided simulation. Studied multistage quantization problem in the Turbo decoding section, especially for the characteristics of transmission channel inlinear hydrophone array. Designed the real program in underwater circuit nodes.4. Studied and implemented complete protocol stack of linear arraycommands, data and synchronization signals transmission in marine environments,including the ship-sea communications, inter-packet communications andcommunications in packages. Designed a layered open command and data transferprotocol, and a storage file format compatible with the SEG Y industry standardformat. Put the protocol stack in the actual hydrophone linear array, formed a reliabletransmission system.5. For different occasions, this paper designed a variety of master software.Achieved long-term uninterrupted data receiving based on double ping-pong structurememory-mapped data files, the SEG Y underwater acoustic detection standard formatdata file storage, and the real-time displaying based on waveform of the MATCOMand other functions.6. Obtained the real data sets through data acquisition experiments held intwo different regions of outfields. Verified the reliability of the linear array dataacquisition and transmission system.