| The EM 122 is designed to perform seabed mapping
to full ocean depth with an unsurpassed resolution, coverage and accuracy. The
system is cost effective, reliable, and easily operated. The design of the EM
122 is based on more than 50 years of hydrographic experience with echo
sounders, sonars and underwater positioning for civilian and military use. It is
the latest model in a series of deep sea multibeam echo sounders started with
the EM 12 in 1990 and followed by the EM 121 and the EM 120, of which about 40
systems are operational. |
| Up to four times better resolution |
| It uses the same transducers as in the EM 120 but
with new electronics and software. Compared with the EM 120 the EM 122 has up to
four times the resolution in terms of sounding density through inclusion of
multiping capability and more than twice the number of detections per swath.
High density signal processing is a major improvement, to keep the acoustic
footprint size small even for the outer beams in the swath. In typical ocean
depths a sounding spacing of about 50 m across and along is achievable. |
| 25 percent more swath width |
The achievable swath width of
the EM 122 is in the order of 30,000 m, or about 25% more than possible with the
EM 120. This is obtained by using long FM chirps which gains about 15 dB in
signal to noise ratio compared to CW pulses. The EM 122 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). |
| Meeting the strictest IHO requirements |
| Including
a higher frequency multibeam echo sounder such as EM 710 with the EM 122 system
can give a total system solution meeting the strictest IHO requirements for all
water depths. As proven with the EM 120, an accuracy of better than 0.2% of
depth in deep waters is readily achievable with the EM 122. |
| Performance |
|
Operating
frequency......................................................................................................12
kHz
Depth
range...........................................................................................................20-11000
m
Swath
width....................................................................................6
x Depth, to approx 30 km
Pulse
forms..................................................................................................CW
and FM chirp
Swath profiles per
ping....................................................................................................1
or 2
Motion compensation:
-
Yaw..................................................................................................................±
10 degrees
-
Pitch.................................................................................................................±
10 degrees
-
Roll...................................................................................................................±
15 degrees
Sounding pattern..................................................................Equi-distant
on bottom/equiangular
Depth resolution of
soundings...........................................................................................1
cm
High resolution
mode...........................................................................High
Density processing
Sidelobe
suppression....................................................................................................-
25 dB
Suppression of sounding artefacts.........................................9 frequency coded
transmit sectors
Beam focusing.............................................On transmit (per sector) and on
reception (dynamic)
Beamforming
method...............................................................................................Time
delay
Gain
control.............................................................................................................Automatic
Swath width control..Manual or automatic, all soundings intact even with reduced
swath width
Seabed imagery/sidescan sonar
image.......................................................................Standard
Water column
display.................................................................................................Standard
Mammal
protection....................................................................................................Standard
Multi frequency operation.....................Yes, by integration with EM 3002, EM 710
and/or EM 302
Sub bottom profiling............................................................... Yes,
by integration with SBP 120 |
