New Transducers 250C ユーザーズマニュアル

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ASIC

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PERATION

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NDERSTANDING

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ONAR

The area covered by the transmitted sound waves is determined by 

the cone angle of the transducer and the water depth. Cone angles 

may vary among different types of transducers. For example, 

a 50kHz frequency may provide a wide 40° cone angle with a 

coverage width that is approximately 2/3 of the water depth. As 

shown in the diagram on the right, the 40° cone angle (50kHz 

frequency) approximately covers the area of a 20-foot diameter 

circle at a 30-foot depth. A 200kHz frequency may provide a narrow 

10° cone angle with a coverage width that is approximately 2/10 of 

the water depth. As shown, the 10° cone angle (200kHz frequency) 

approximately covers the area of a 6-foot diameter circle at a 30-foot 

depth. 
When using the Fishfinder 250/250C with Frequency set to Dual, 

the unit alternately transmits 50kHz and 200kHz signals and 

combines the information. This allows the unit to cover a large 

area and still retain good bottom resolution. The unit uses the 

narrow cone angle (200kHz) to display detailed bottom information 

(keeping dead zones to a minimum) and the wide cone angle 

(50kHz) for the large coverage area.

200kHz - 10˚ cone angle

6-foot coverage at 30-foot depth

50kHz - 40˚ cone angle

20-foot coverage at 30-foot depth

Transducer coverage

Fish returns from the wide and narrow beams appear differently on 

the display. The wide beam tends to show longer fish returns than 

the narrow beam, as shown below.

Wide cone angle

Narrow cone angle