Browsing by Author "Farinha, L."
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- Acoustic maritime rapid environmental assessment 2004 during the MREA'04 sea trialPublication . Jesus, S. M.; Soares, C.; Felisberto, P.; Silva, A.; Farinha, L.; Martins, C.Environmental inversion of acoustic signals for bottom and water column properties is being proposed in the literature as an interesting concept for complementing direct hydrographic and oceanographic measurements for Rapid Environmental Assessment (REA). The acoustic contribution to REA can be cast as the result of the inversion of ocean acoustic properties to be assimilated into ocean circulation models specifically tailored and calibrated to the scale of the area under observation. Traditional ocean tomography systems and methods for their requirements of long and well populated receiving arrays and precise knowledge of the source/receiver geometries are not well adapted to operational Acoustic REA (AREA). The Acoustic Oceanographic Buoy (AOB) was proposed as an innovative concept that responds to the operational requirements of AREA. That concept includes the development of water column and geo-acoustic inversion methods being able to retrieve environmental true properties from signals received on a drifting network of acoustic-oceanographic sensors - the AOBs. An AOB prototype and a preliminary version of the inversion code, was tested at sea during the Maritime Rapid Environmental Assessment 2003 (MREA’03) sea trial and was reported in [1]. On a separate register it should be noted that the characterization of the environment between the source and the receiver also contributes to the identification of the acoustic channel response and therefore provides a basis for fulfilling the objectives of project NUACE1. The present report describes the data sets and results gathered during the MREA’04 sea trial that took place from 29 March to 19 April 2004 off the west coast of Portugal, south of Lisboa (Portugal), with the objectives of testing an improved version of the individual AOB and its functionality in a simple network. The acoustic part of the experiment lasted for four days between April 7 and April 10, 2004 and involved the transmission and reception of pre-coded signals along range-dependent and range-independent acoustic tracks.
- Ultra light vertical array remote data acquisition systemPublication . Felisberto, P.; Farinha, L.; Soares, C.In the framework of the ATOMS project, a project devoted to study uppwelling processes off the S. Vicente Cape, Portugal, by oceanographic and acoustic means, it was requested to adapt an existent underwater acoustic acquisition system named Ultra Light Vertical Array (ULVA) to fulfil the project requirements. The ULVA system was a vertical instrumented with up to 16 hydrophones and various non-acoustic sensors (thermistors, tiltmeters and pressure gauges). The ULVA system was used during the INTIFANTE project sea trial, where the acquired data were transmitted through a radio link to a remote PC station located in a vessel for storage, monitoring and online processing. In order to overcome data loses due to radio link fails, identified during the INTIFANTE sea trial, and improve the mobility of the vessel where the PC station is located, a must for the ATOMS project, it was decided to transform the ULVA system into an autonomous acquisition system with local storage facilities, lower power consumption, capability of on line remote quality control of the acquired data and positioning information. The first version of this new system, named Ultra Light Vertical Array/Remote Data Acquisition System (ULVA/RDAS), was described in the report. During the sea trial MREA'04 it was found that an auxiliary UHF radio link used to send some commands to the ULVA, like switch on/off the power or switch on/off the array electronics, remains a source of problems in the ULVA/RDAS. Thus, it was decided to remove the UHF link from the system, emulating its facilities by new developed hardware. In this new version (second) of the ULVA/RDAS system, it was also introduced a new monitoring software, in order to improve its robustness and share a common user interface with other SiPLAB acquisition systems. This report describes the actual ULVA/RDAS system (version 2) and is intended as a system reference and user guide.