System Description; Em 712B, Upgrade From Em 710 - Kongsberg EM 712 Maintenance Manual

Kongsberg EM 712

System description

The EM 712 multibeam echo sounder is a high to very high resolution seabed mapping
system.
The EM 712 multibeam echo sounder is capable of meeting all relevant survey standards.
The system configuration can be tailored to the user requirements, allowing for choice of
beamwidths as well as transmission modes. The minimum acquisition depth is from less
than 3 m below its transducers, and the maximum acquisition depth is up to 3600 m.
The EM 712 replaces the EM 710. EM 712 is built with new, state of the art technology.
By increasing the frequency range from 70-100 kHz to 40-100 kHz, the range
performance is greatly improved. The transmit transducer arrays are the same, while the
receive arrays has got a built in preamplifier. The preamplifier reduces the electronic self
noise and this gives extended range capability as long as the external noise (ships noise,
flow noise , sea-state) is low. The EM 712 receiver can be configured for 0.5°, using
two receiver modules. For upgrade from EM 710 to EM 712, the TX and RX frames
plus the transmit array(s) can be reused.
Acrosstrack coverage (swath width) is up to 5.5 times water depth and the maximum
achievable depth is 3600 m. The sounding density is very high, allowing even the very
demanding LINZ special order survey specification for object detection to be met in full.
There are three basic versions of the EM 712:
• EM 712 - Full performance version
• EM 712S (shallow) - Continuous wave (CW) pulse forms only
• EM 712RD (reduced depth) - Short CW pulse only, restricted to 600 m water depth.
The reduced performance versions EM 712S and EM 712RD can be upgraded to full
performance.

EM 712B, upgrade from EM 710

With EM 712B it is possible to upgrade EM 710 to EM 712 without replacing the
transducer modules.
To achieve this we have made a separate Receiver Unit scientifically tailored for
use with the EM 710 receive transducers. The EM 712B Receiver Unit has the same
measurements and weight as the regular Receiver Unit, but performs the preamplification
in the Receiver Unit instead of in the receive transducer.
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