Kongsberg-Simrad EM300 Multibeam Echo Sounder
The EM300 is manufactured by:
Kongsberg-Simrad AS
Horten, Norway
SYSTEM DESCRIPTION
Introduction
The Kongsberg Simrad EM 300 multibeam echo sounder is designed to do
mapping from 10m depth to beyond the continental rises, including the
shallower ocean basins. It operates down to approximately 5000 m depth
with swath widths up to about 5000 m. Small transducers and compact
electronics make the installation easy, and the system accuracy is
generally well within the IHO standards.
The design of the EM 300 is based on more than 50 years of hydrographic
experience with echo sounders, sonars and underwater positioning for
civilian and military use. Kongsberg Simrad is today a part of the
Kongsberg Group, a world wide organisation supplying advanced
instrumentation for civilian, research and military maritime communities.
The Kongsberg Sirnrad EM 300 is a complete system. All necessary sensor
interfaces, data displays for quality control and sensor calibration,
seabed visualization, and data logging are a standard part of the system,
as is integrated seabed acoustical imaging capability (sidescan).
Key features
Operating frequency and coverage sector
Operating frequency and coverage sector
The nominal sonar frequency is 30 kHz with an angular coverage sector of
135 beams per ping at 1 degree. The angular coverage sector and beam
pointing angles may be set to vary automatically with depth according to
achievable coverage. This maximizes the number of usable beams. The beam
spacing is normally equidistant with equiangle available.
Transmission
The transmit fan is split in several individual sectors with independent
active steering according to vessel roll, pitch and yaw. This will place
all soundings on a "best fit" to a line perpendicular to the survey line,
thus ensuring a uniform sampling of the bottom and 100% coverage.
The sectors are frequency coded (30 to 34 kHz), and they are all
transmitted sequentially at each ping. The steering is fully taken into
account when the position and depth of each sounding is calculated, as is
the refraction due to the sound speed profile, vessel attitude and
installation angles. Pulse length and range sampling rates are variable
with depth for best resolution, and in shallow waters due care is taken to
the near field effects. The ping rate is mainly limited by the round trip
travel time in the water up to a ping rate of 10Hz.
Transducer arrays
The EM 300 transducers are linear arrays in a Mills cross configuration
with separate units for transmit and receive. The arrays are divided into
modules that may be replaced by a diver. The arrays are 1 degree
beamwidth for receive and transmit. The physical array lengths are 3.3
meters. A combination of phase and amplitude detection is used, resulting
in a measurement accuracy practically independent of beam pointing angle.
Created July 2002
Last Updated 15 February 2003
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