Furuno GP-3700F, Operator'S Manual

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11. ECHO SOUNDER
11-2
11.2.1 Single frequency display (50 kHz or 200 kHz)
Low frequency (50 kHz)
The sounder uses ultrasonic signals to detect bottom
conditions. The lower the frequency of the signal, the
wider the detection area. Therefore, the 50 kHz frequen-
cy is useful for general detection and judging bottom con-
dition.
High frequency (200 kHz)
The higher the frequency of the ultrasonic signal, the bet-
ter the resolution. For this reason the 200 kHz frequency
is ideal for detailed observation of schools of fish.
*: In this chapter, the combination of VRM and time marker on the echo sounder dis-
play is referred to as “cursor”.
High
freq.
Low
freq.
Coverage area
Water
temperature
Ship
speed
Gain
Sound
reference
Temp. scale
Color bar
Bottom
School of fish
Depth
Frequency
Depth scale
Picture advance speed
Water temp. graph
VRM* (variable range marker)
Time marker*
Minutes and seconds for time marker/
Depth for VRM