Blar i Havforskningsinstituttet på emneord "ekkolodd"
Viser treff 41-60 av 66
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Nominal performance measures for two 710-kHz transducers
(ICES CM Documents;1992/B:9, Working paper, 1992)Two new transducers have been designed by SIMRAD for the EK500 echo sounding system. The nominal operating frequency is 710 kHz. Each transducer is composed of a single, circular, active element, with diameter of 25 or ... -
Note on the measurement of target strength of fish at sea
(ICES CM Documents;1966/F:9, Working paper, 1966) -
Observation of fish behaviour, density and distribution around a surveying vessel by means of a deployable echo sounder system
(ICES CM documents, Working paper, 1999)Detailed acoustic obsewations of fish behaviour, distribution and density in the trawl area are necessary in order to establish quantitative relationships between trawl samples and fish density. Acoustic observation close ... -
Observed avoidance behaviour in herring in relation to passage of an echo survey vessel.
(ICES CM Documents;1979/B:18, Working paper, 1979) -
On subjectivity in the judging of acoustic records; comparison of degree of homogenity in allocation of echo values by different teams
(ICES CM Documents;1993/B:21, Working paper, 1993)On four fish abundance estimation surveys in the Barents Sea, january-february 1993, the acoustic records were judged by two independent teams. We have analyzed the degree of homogenity in allocation of echo values to ... -
On the shape, size and density of North Sea herring schools as mapped by echo integration and accurate sonar projection
(ICES CM Documents;1993/B:16, Working paper, 1993)The shape and horizontal extent of herring schools in the North Sea have been mapped by a naval sonar (SIMRAD SA 950) with narrow horizontal beam width. The density of schools that were passed over was measured by the ... -
Optimal acoustic beam pattern corrections for split beam transducers
(ICES CM Documents;1990/B:30, Working paper, 1990)Precise in situ target strength estimates of fish can only be made when the effect of the transducer directivity is totally removed from the recorded target amplitudes. By guiding a standard calibration target through the ... -
Optimizing copper spheres for precision calibration of hydroacoustic equipment
(Journal article; Peer reviewed, 1982)n operational definition of backscattering cross section is developed for the wideband reception of finite echoes. This is supported by relative measurements on a set of copper spheres by each of four echo sounders operating ... -
Postprocessing system for echo sounder data
(Journal article; Peer reviewed, 1991)Echo sounding is a powerful and widely used technique for remote sensing of the marine environment. In order to enhance the power of the echo sounder, a postprocessing system has been designed and realized in standard ... -
Power-budget and echo-integrator equations for fish abundance estimation
(Fisken og Havet;10-2013, Research report, 2013-12-31)For abundance estimation and species identification on fisheries acoustic surveys, control with temperature and finite amplitude effects in the sea demands the calibration factor C of the conventional echo-integrator ... -
Probing the deep: Acoustic characterization of the Mid-Atlantic Ridge ecosystem
(Journal article; Peer reviewed, 2006) -
Rapport om tokt med F/F "Johan Hjort" til Vest Grønland i april/mai 1964
(Fisken og havet;1964 - Nr. 7, Journal article, 1964) -
Report of the PGNAPES Scrutiny of Echograms Workshop (WKECHOSCRU) [16–18 February 2009 Bergen, Norway]
(ICES CM documents;2009/RMC:02, Working paper, 2009) -
Report on echo-integrator surveys for sprat undertaken in the North Sea during the 1981 -82 winter season.
(ICES CM Documents;1982/H:13, Working paper, 1982) -
Simple calibration of a split-beam echo-sounder
(ICES CM Documents;1986/B:8, Working paper, 1986) -
Simulating echograms
(ICES CM Documents;1989/B:6, Working paper, 1989)Simulation of echo data can be useful for verifying echo integrators realized in computer software. A model is presented which associates distinct stochastic processes with each of the following: bottom depth; number, ... -
Some methods for the generation of combined-frequency echograms
(Fisken og havet, Research report, 2002)Calibrated and digitised data from two or more discrete echo sounder frequencies can be combined for the purpose of separating and extracting the acoustic scattering from zooplankton and fish in mixed recordings. Methods ... -
Some pitfalls of short-range standard-target calibration
(ICES CM Documents;1996/B:36, Working paper, 1996)Often it is necessary or desirable to perform a standard-target calibration at rather short range, for example, because of shallow water or interest in measuring animals at short range. A number of general range-dependent ... -
Sonar kurs for fiskere
(Fisken og havet;1964 - Nr. 2, Journal article, 1964)