Raymarine A65, Operation Instructions Manual

Page: 200 / 390

15.1 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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Sonar is effective at a range of speeds. In deeper
waters the CHIRP bandwidth is automatically
optimized to improve bottom lock and the detection
of moving objects (e.g. fish) in the wider water
column.
CHIRP sonar screen example
CHIRP DownVision TM overview
DownVision TM produces a wide–angle side-to-side
beam and a thin fore-to-aft beam. The coverage of
the
DownVision
TM
beam is a water column directly
beneath and to the sides of the vessel.
DownVision TM beam
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LightHouse multifunction display operation instructions