User manual NORTHSTAR 490 ECHOSOUNDER

[. . . ] Northstar 490 Echo Sounder Operations Manual Limited warranty policy Northstar Technologies, Inc. warrants the Northstar 490 to be free from defects in materials and workmanship for a period of two (2) years. This warranty applies to the original purchaser and to any subsequent owner during the warranty period, which begins on the date of shipment of the unit, F. O. B. Acton, Massachusetts, to an authorized Northstar dealer. [. . . ] For example, if you select a signal level of 3, echo strengths of 0 through 3 are all displayed using the same color. Press RETURN to go back to the ECHO screen. Suppressing interference (the noise limiter) The noise limiter reduces the adverse effects of interference from other nearby echo sounders or electronic devices. however, the noise limiter may cause some very weak echoes to be made smaller or entirely eliminated, since it removes any echoes that aren't sustained for at least two pings. At the PICTURE screen, press NOISE LIMITER. At the NOISE LIMITER window, press the CURSOR PAD up to turn the noise limiter on (or press NOISE LIMITER again). Press the RETURN key to go back to the ECHO screen. Turning the noise limiter on changes a portion of the PICTURE key tab from green to yellow, as a reminder. 490 Echo Sounder Operations Manual Rev. B2 Page 3-5 Chapter 3 - Adjusting the Echo Sounder Picture Selecting the color bar (hue) and white level Understanding the color bar The color bar displayed at the extreme left of the ECHO screen shows the range of colors used to display different echo strengths. Weaker echoes are displayed with colors near the bottom of the scale, and stronger echoes are displayed with colors near the top. You can choose any one of nine palettes of colors to represent the echo strengths from weakest to strongest. · · · · Color bar #1 is the one most often used. Color bar #2 is similar but with fewer colors, to aid visibility under some conditions. Color bars # 3-8 are additional variations with different background colors. Color bar #9 uses only a single color, ranging from very dark to very bright. Selecting the color bar (hue) To select the color bar: 1. At the HUE AND WHITE LEVEL window, press the CURSOR PAD left or right to select the color bar desired, or use the KEYPAD to manually enter the number of the color bar. Page 3-6 490 Echo Sounder Operations Manual Rev. B2 Chapter 3 - Adjusting the Echo Sounder Picture Hue and white level window 4. Press RETURN to go back to the ECHO screen. Setting the white level You can replace any single color in the color bar with white. On the HUE AND WHITE LEVEL window, press the CURSOR PAD up or down to select that color. To remove the white level and return to using all the colors on the color bar, press the CURSOR PAD down until the white level moves off the color bar. 490 Echo Sounder Operations Manual Rev. B2 Page 3-7 Chapter 3 - Adjusting the Echo Sounder Picture Page 3-8 490 Echo Sounder Operations Manual Rev. B2 Understanding Depth Settings Viewing the seabed depth . 4-2 Setting the picture's shift (starting depth) . 4-4 chapter explains how to override the system's automatic depth settings and manually control the depth range shown on the screen, and how to use the depth marker. This 490 Echo Sounder Operations Manual Rev. [. . . ] The actual path of your vessel relative to the surface of the earth. Distracting echoes caused by turbulence, plankton, etc. The horizontal movement of water caused by tidal or other forces. A choice made automatically by the echo sounder; some defaults can be overridden in partial automatic mode. [. . . ]