GP1670F_1870F Operator's Manual - Furuno USA

7.3 How to Activate the Fish FinderSelect a fish finder display at the home screen. See section 1.8.7. FISH FINDER OPERATIONS7.4 How to Select a DisplayYour fish finder has these display modes: single frequency (50 kHz or 200 kHz), dualfrequency (50 kHz + 200 kHz), bottom lock, bottom zoom, marker zoom, A-scope, andbottom discrimination.7.4.1 How to select a single frequency or dual frequencySingle frequencyThe single frequency display shows eitherthe low-frequency or high-frequency pictureon the full screen. Select a frequency accordingto your purpose.• A low frequency gives a wide detection area.Use the low frequency for generalsearch and to find bottom conditions.• A high frequency gives better resolution.Use the high frequency to inspect a schoolof fish.LowfrequencyTo select a single frequency display, openthe RotoKey menu, select [Frequency] then [200 kHz] or [50 kHz].HighfrequencyDual frequencyThe dual frequency display provides both low- and high-frequency pictures. Use thedual frequency display to compare the same picture with two different soundingfrequencies.The low-frequency picture is on the left, and the high-frequency is on theright.LowfrequencyHighfrequencyFreq.(kHz)LowHighBeamwidth Resolution DetectionrangeWideNarrowLowHighDeepShallowBottomtailLongShortTo select a dual frequency display, open the RotoKey menu then select [Frequency]and [Dual].7-3