138 GPSMAP 496 Owner’s ManualSetting up and Using Sonar > Using the Sonar PageZoom—used to quickly select a zoom scale or to split the screen.When a scale other than no Zoom is selected, the Adjustment Menushows a new selection labeled View or Span. The Zoom function isdivided into six levels:2X Split—shows two reduced-size sonar pictures at the sametime. The right half of the screen shows the complete sonarpicture at its original scale. The left half shows a portion of theoriginal picture at 1/2 depth scale.2X Zoom—shows the 2X zoomed picture on the full screen.4X Split—shows two reduced pictures, the right at the originaldepth scale and the left at 1/4 the original depth scale.4X Zoom—shows the 4X zoomed picture on the full screen.Btm (Bottom) Split—shows two reduced pictures, the right atthe original depth scale and the left showing sonar returns fromthe bottom up. All target depths read as a distance from thebottom.Btm (Bottom) Lock—shows returns from the bottom up on thefull screen.notE: Quickly zoom in and out of the Sonar Page by pressingthe in and out keys. Stop the zoom function by pressing theout key until the no Zoom setting appears.••••••View/Span—available when a Zoom scale other than no Zoom isselected. The View or Span setting is used to change the viewing rangeof a zoomed screen. If the screen is 2X or 4X split, only the zoomedportion on the left side of the screen is affected by the change. If thescreen is Bottom Split or Bottom Lock, Span adjusts how far off thebottom the unit shows data.gain—allows you to control the sensitivity of the unit’s receiver,which provides flexibility in what is shown. To see more detail,increase the receiver sensitivity by selecting a higher gain. If there istoo much detail or if the screen is cluttered, select a lower gain.target Level—adjusts which colors are used to show sonarinformation. A Color Bar appears on the right side of the screen asyou adjust this setting. A higher percentage results in more strong-signaled colors shown on the sonar screen. A lower percentageresults in more weaker-signaled colors shown on the sonar screen.This setting does not increase or decrease the unit Gain.Whiteline—controls how the unit shows information about thebottom type (hard or soft). With the Whiteline Off, the bottom returnshows as red. Set Whiteline at normal or 1–100% to determinebottom hardness. See page 145 for more information.Frequency—allows you to choose a transducer frequency.Frequency refers to the “pitch” of the sound that the transducersends and receives.
