IMPACT SUBSEA
INNOVATIVE UNDERWATER PRODUCTS
www.impactsubsea.com
Document No:
0000.1991 |
Version No:
1.6 | 6
th
October 2020
31
6.2.4 Directional Index (DI)
The Directional Index gives a reduction in noise level, governed by the properties of the
transmit/receive transducer.
An omni-directional transducer will theoretically pick-up noise from all directions. A
directional transducer will hear noise from only one direction. Thus, a method of reducing
the apparent background noise is to utilise a highly directional transducer.
The ISS360 sonar utilises a 23° fan beam which is 2.2° wide. Meaning that any potential
interference effects, which exist outside of this beam, will not have a negative impact on
the operation of the unit.
6.2.5 Detection Threshold (DT)
The Detection Threshold is a property of the acoustic system. It is defined as the minimal
signal to noise ratio required in order to detect the acoustic signal.
The threshold can be lowered by minimising the device self-generated noise: utilising
advanced acoustic signalling, whilst having a highly capable matching filter or a highly
sensitive transducer on the receive side to detect the signal.
The ISS360 Sonar utilises a proprietary acoustic correlator to detect the returning acoustic
signal, low noise digital electronics and a highly sensitive composite transducer to enable it
to detect extremely small acoustic signals.
An appreciation of the Sonar equation will provide an understanding of the fundamental
operation of the ISS360 Sonar. It may help during installation and fault-finding, as it
provides an indication to influential factors.
