Environmental assessment with a RAnDom field of Acoustic Receivers RADAR

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Publications

A post-detection maximum ratio combiner. Experimental assessment on high diversity underwater channels

Publication . Silva, A.; Jesus, S. M.

Maximum Ratio Combiner (MRC) is a diversity combining technique applicable to underwater communications when the data transmitted by a single projector is received by more than one antenna/node. Post Detection MRC (PD-MRC) performs a weightedsum over initial detected outputs of multiple nodes. PDMRC can be applied to noise-only or ISI-only channels with the weights computed from the signal to noise ratio or from the channel impulse response of each node, respectively. In this paper it is shown that in the presence of noisy-ISI channels the weighs can be computed from the detector output constellation of each node. A performance of the PD-MRC is evaluated using real data collected during RADAR’07 experiment. Results show that a gain is always attained using two nodes in the PDMRC as compared to the node having the best MSE. Moreover, the PD-MRC gain is higher when both nodes present a similar MSE.

2011Journal article

Open Access

RBR thermistors array for AOB2

Publication . Zabel, F.; Martins, C.

This report describes an electronic circuit board for interfacing the RBR thermistor chain manufactured by Richard Bracker Research, Ontario (Canada), with the Acoustic Oceanographic Buoy (version 2) - AOB2. The interface consists on a set of bridge amplifiers and associated electronics for converting the NTC thermistor signals into temperature related values in the data acquisition CPU control of the AOB2. With this board the temperature measured along the RBR thermistor chain array can be monitored on real time together with the acoustic data via the wireless lan network to which the AOB2 is associated.

2006Report

Open Access

The acoustic oceanographic buoy. A light acoustic data acquisition system

Publication . Soares, C.; Zabel, F.; Martins, C.; Silva, A.; Jesus, S. M.

The Acoustic Oceanographic Buoy (AOB) is a light acoustic receiving device that incorporates acoustic and non-acoustic signals received in various channels along a vertical line array that provide oceanographic and environment measurements all of which are uniquely GPS time referenced. The physical characteristics of the AOB, in terms of size, weight and autonomy, will tend to those of a standard sonobuoy with, however, the capabilities: of local data storage, dedicated signal-processing, GPS self localizing, real-time monitoring and online data transmission.

2007Conference object

Open Access

Maritime rapid environmental assessment - Blue Planet'2007. Acoustic oceanographic buoys data report

Publication . Jesus, S. M.; Zabel, F.; Martins, C.

Among the existing panoply of instrumentation for Rapid Environmental Assessment (REA), underwater unmanned vehicles, satellite remote sensing and oceanographic drifters attract particular attention. In the last years, there has been a growing interest in coupling purely oceanographic surveys and acoustic measurements, in order to provide a final environmental image that is not only oceanographically consistent but also acoustically coherent for the area and period of interest. Thus, the usage of remote acoustic equipment is becoming an integrand part of the REA equipment list. One of the major characteristics of REA equipment is its unique capability for remote, often unsupervised, operation and compactness.

2007Report

Open Access

The acoustic oceanographic buoy telemetry system: an advanced sonobuoy that meets acoustic rapid environmental assessment requirements

Publication . Silva, A.; Zabel, F.; Martins, C.

In the past few years Rapid Environmental Assessment (REA), applied to shallow waters, has become one of the most challenging topics in ocean acoustics. The REA concept evolved after the cold war when the outset of regional conflicts shifted the potential operational areas from open ocean towards littoral areas, and has been identified by NATO as a new warfare requirement.

2007Journal article

Open Access