Raymarine gS Series, Инструкция по установке и эксплуатации, Страница: 96 / 208

17.1 How the fishfinder works
The fishfinder application uses a sonar module and a suitable
sonar transducer. The sonar module interprets signals from the
transducer and builds up a detailed underwater view. Various
sonar technologies are available, all of which work on the same
basic principles.
The sonar transducer sends pulses of sound waves into the
water and measures the time it takes for the sound wave to
travel to the bottom and back. The returning echoes are affected
by bottom structure and by any other objects in their path,
for example reefs, wrecks, shoals or fish. The Sonar module
interprets these signals and builds up a detailed underwater view
which is displayed in the Fishfinder application.
The Fishfinder application uses colors and shading to indicate
the strength of the returns. You can use this information to
determine the bottom structure, the size of fish and other objects
in the water, such as debris or air bubbles
Note: Some transducers include additional sensors to
measure water temperature and/or speed.
17.2 Sonar technologies
Traditional sonar technology
Traditional sonar uses a single carrier frequency or carrier wave
for the sonar ping. The sonar works by measuring the time
it takes the ping echo to return to the transducer to determine
target depth.
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CHIRP technology
CHIRP sonars use a swept frequency 'CHIRP' signal which can
distinguish between multiple close targets, this enables the sonar
to display multiple targets instead of large combined targets that
you would see when using traditional non-CHIRP sonar.
Benefits of CHIRP include improvements to target resolution,
bottom detection even through bait balls and thermoclines and
detection sensitivity.
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CHIRP Sonar overview
CHIRP sonar produces a conical shaped beam, the coverage of
the conical beam is the water column directly beneath the vessel
Conical beam
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gS Series