User manual FURUNO CH-250

[. . . ] Back COLOR LCD SEARCHLIGHT SONAR CH-250 C Your Local Agent/Dealer 9-52, Ashihara -cho, Nishinomiya, Japan Telephone: Telefax: 0 7 9 8 - 6 5 - 2111 0798-65-4200 All rights reserved. Printed in Japan FIRST EDITION K2 : : M A R. O M E -1 3 1 6 0 C H -2 5 0 SAFETY INSTRUCTIONS WARNING ELECTRICAL SHOCK HAZARD Do not open the equipment. Only qualified personnel should work inside the equipment. Immediately turn off the power at the switchboard if water leaks into the equipment or something is dropped in the equipment. [. . . ] Horizontal range and depth appear on the screen. To erase the depth and horizontal range markers, press the [R/B] key again, or place the cursor on the depth or horizontal range marker and press the [R/B] key. Horizontal range 94 105 NAV DATA Horizontal range marker Depth Depth marker Figure 3-12 Depth and horizontal range markers 3-9 3. 11 Adjusting the Picture 3. 11. 1 Displaying weak echoes clearly Echoes from targets (such as the bottom or a fish) return to the transducer in order of the distance to them, and when their intensities are compared at the transducer face, those from nearer targets are generally stronger when their reflecting properties are nearly equal. The sonar operator will be quite inconvenienced if these echoes are directly displayed on the screen, since he won't be able to judge the actual size of the target from the size of echoes displayed on the screen. To overcome this inconvenience, use the TVG function. It compensates for propagation loss of sound in water: amplification of echoes on short range is suppressed and gradually increased as range increases, so that similar targets are displayed in similar intensities irrespective of the ranges to them. The TVG also functions to suppress unwanted echoes and noise which appears in a certain range area on the screen. Press to select MENU and then press MENU TVG LEVEL TVG DISTANCE GAIN ADJ RES. COLOR or to select the VERT menu. COMN HORZ VERT ES SHORT-CUT SYS 4. 0 4. 0 0 LOG : SELECT : CHANGE MENU: END Figure 3-13 VERT menu 3. Press or to select TVG DISTANCE and press TVG DISTANCE GAIN Hi to show the following dialog box. 4. 0 Lo 200m 3-10 4. Press or to adjust TVG distance, considering sea conditions. The larger the figure the greater the distance at which the TVG works. TVG Distance Setting Meters Feet Passi/braza Hiro 0 3 10 2 2 0. 5 8 30 5 5 1. 0 20 70 10 10 1. 5 40 130 20 20 2. 0 60 210 40 40 2. 5 100 330 60 60 3. 0 130 410 80 80 3. 5 160 520 100 100 4. 0 200 660 120 130 4. 5 250 820 150 170 5. 0 320 1040 180 210 . . . . Press or to close the dialog box and return to the VERT menu. To suppress reflections by the sea surface or plankton, select TVG LEVEL and press 7. Press or to adjust TVG LEVEL, considering sea conditions. The larger the figure the less the gain over distance. Press the [MENU] key to register your selection and close the menu. Wrong Correct Level too high Distance too high Figure 3-14 Examples of proper and improper TVG 3. 11. 2 Suppressing noise and interference You may encounter occasional or intermittent noise and interference as shown below. This is mostly caused by electrical equipment, engine, propeller noise from own ship, or noise from other sonars being operated nearby. If interference appears, turn on the interference rejector in the COMN menu to suppress it. Interference rejector ON Interference (In this display, interference shows itself every 6°. ) Figure 3-15 Appearance of interference 3-11 3. 12 Vertical Menu Overview This section presents an overview of the items on the VERT menu. Press to select MENU and then press MENU TVG LEVEL TVG DISTANCE GAIN ADJ RES. COLOR or to select the VERT menu. COMN HORZ VERT ES SHORT-CUT SYS 4. 0 4. 0 0 LOG : SELECT : CHANGE MENU: END Figure 3-16 VERT menu 3. Press or to select item desired. to show corresponding dialog box. Press the [MENU] key to register your selection and close the menu. 3. 12. 1 Vertical menu description TVG LEVEL: Compensates for propagation loss of sound in water. [. . . ] 2-17 position mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18 selection of mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17 Test pattern. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8 TILT control echo sounder mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ]