Raymarine E70085 Dragonfly, Operation Manual

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2.3 Product information
Information relating to your product is shown below
Part
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Features
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E70085
• Internal GPS.
• Internal 2 channel CHIRP sonar
module
– Sonar — Centred 200 KHz
– DownVision — Centred 350 KHz
.
CHIRP Sonar overview
Sonar interprets signals from the transducer and builds up a
detailed underwater view. The 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.
Sonar produces a 25° conical shaped beam, the coverage of the
conical beam is the water column directly beneath the vessel.
Conical beam
D12784-1
Sonar is effective at a range of speeds. In deeper waters the
CHIRP bandwidth is automatically restricted to improve bottom
lock and the detection of moving objects (e.g. fish) in the wider
water column.
CHIRP sonar screen example
CHIRP DownVision overview
DownVision interprets signals from the transducer and builds up
a detailed underwater view. The 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.
DownVision produces a 60° side to side and 1.4° fore to aft
beam. The coverage of the DownVision beam is a water column
directly beneath and to the sides of the vessel.
DownVision beam
D12777-1
DownVision is effective at lower vessel speeds. In deeper
waters the CHIRP bandwidth is automatically restricted to
improve bottom lock and the detection of moving objects (e.g.
fish) in the wider water column.
The wide, thin beam produces clear target returns. The use of
CHIRP processing and a higher operating frequency provide
a more detailed image, making it easier to identify bottom
structures around which fish may reside.
CHIRP DownVision screen example
Handbook and product information
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