Results from two advanced complementary research echosounding systems are examined and discussed The more complex system is a Hydrographic Wide Swath Sweeping Survey Echosounder for shallow and deep water applications (Hydrosweep) for accurate bathymetric surveys and terrain-following navigation The second system (Parasound) is a hull-mounted Dual Channel Parametric Narrow Beam Deep Sea Survey and Sub Bottom Profiling Echosounder with the functions of a wide beam (20° at 18 kHz, 12° at 33 kHz), narrow beam (25°at 33 kHz, 2° and 4°at 18 kHz), and sub-bottom profiler (4° at 2 5–5 5 kHz).

Both systems have been developed under sponsorship of the Ministry of Research and Technology of the Federal Republic of Germany for the new research vessel Meteor.

OVERALL CONCEPT OF THE HYDROACOUSTIC RESEARCH SYSTEM ON BOARD RV METEOR (see Fig. 1)

Both systems described are part of an overall hydro-acoustic research system consisting of: hydrographic sweeping survey system (Hydrosweep), parametric survey echosounder (Parasound), standard survey echosounder (Deso), pinger signal and slave survey recorder (Deso), multi-beam fishery sonar, fishery net-sounder, navigation echosounder (461), sonar doppler log (Dolog), sound velocity sounder (C-Sonde), various slave recorders (Deso), various slave colour scopes (320), various distal depth indicators (Filia), gyro-stabilized heave/roll/pitch sensor (Heco) All sub-systems of the hydroacoustic research system are connected to a central echosounding control system (Echocontrol) which cross-connects trigger and pre-trigger signals, calculates and distributes blanking delay signals; converts all echosounding signals to a standard carrier frequency for distribution to slave recorders and colour scopes; records or replays a signal to/from a tape deck, distributes common draught, sound velocity, heave (roll/pitch), paper speed, time, and annotation text data to all survey echosounders, slave recorders and slave colour scopes; distributes all distal depth values to remove indicators; provides an instant monitor display of all echosounder status data and of used sounding signals in the various laboratories (Fig 2).

Fig. 1 Hydroacoustic research system on board RV Meteor(available in full paper)

Fig. 2 Echosounder control system-monitor(available in full paper)

It was for us as a manufacturer an exceptional situation we could supply all hydroacoustic subsystems, partly as existing standard products, but the survey echosounders all had to be developed and produced anew in parallel (and in time) within a contract period of only 18 months Technically, this gave us the chance to introduce a very high amount of commonality throughout all products by hardware components such as silent and dust-free thermo-recorders, high resolution colour displays, and-most importantly-a very high commonality of spare parts.

THE HYDROGRAPHIC SWEEPING SURVEY SYSTEM (Fig. 3)

The main characteristic of the Hydrosweep equipment is the large sector of 90° covered by a fan of 59 pre-formed beams This is made possible by a patented real time calibration method without which refraction effects would lead to large measurement errors in the case of the outer sound beams With this method the fan of beams from the echosounder is transmitted in the ship's longitudinal direction at regular intervals The ‘oblique profile’ measured in this way is stored During the distance that has already been sailed.

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