Kongsberg Simrad ES80, Installation Manual

Page: 56 / 312

54
416739/A
Signal-to-noise ratio (often abbreviated SNR or S/N) is a measure used in science and
engineering that compares the level of a desired signal to the level of background noise.
It is defined as the ratio of signal power to the noise power, often expressed in decibels.
A ratio higher than 1:1 (greater than 0 dB) indicates more signal than noise. While SNR
is commonly quoted for electrical signals, it can be applied to any form of signal [...].
Wikipedia, Copied September 2013
The signal is the echo that we want to know something about, while the noise is any
unwanted signals or disturbances. The echo must be detected in the noise and therefore it is
necessary to keep the noise level as low as possible in order to obtain high interpretation.
The noise that contributes to the signal to noise ratio may be divided into the following
types of noise:
• Self noise
• Ambient noise
• Electrical noise
• Reverberation
• Fishing gear noise
A The transducer can pick up noise from
• Biological disturbances
• Interference
• Cavitation
• Propeller noise
• Flow noise
• Acoustic noise from other hydroacoustic systems
B The transducer cable is long, and may pick up electric noise from generators, pumps,
cooling systems and other electric or electromechanical devices.
Simrad ES80 Installation Manual