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Sonar Operation at Cabela's

Sonar Operation

Author: Lowrance

After starting your boat, go to a protected cove and stop. Leave the engine on. You may want to take a partner along to operate the boat while you learn how to use the sonar. Press the sonar unit’s ON key and idle slowly around the cove. You’ll probably see a screen similar to the one to the left. The dashed line at the top of the screen represents the surface. The bottom shows in the lower part of the screen. The current water depth (33.9 feet) shows in the upper left corner of the screen. The depth range in this example is 0 to 40 feet. Since the unit is in the automatic mode, it continually adjusts the range, keeping the bottom signal on the display.
Fish Symbol ID
Fish Symbol ID™
Every Lowrance LCG offers the convenience of our Advanced Fish Symbol I.D. Activated by the press of a button, Advanced Fish Symbol I.D. lets your unit do the work of interpreting return sonar signals. Advanced Fish Symbol I.D. works in automatic mode only. If you turn it on while in manual mode, it will switch to automatic mode. Fish and other suspended targets are clearly displayed as fish-shaped symbols in four different sizes.

Advanced Fish Symbol I.D. is designed to give a simplified, easy to interpret display of suspended targets that are assumed to be fish. After gaining experience with your sonar, you will probably turn it off much of the time so you can see all of the detailed information on fish movement, thermoclines, schools of baitfish, weed beds, bottom structure, etc.

ASP™(Advanced Signal Processing)
Advanced Signal Processing (ASP) is another exclusive Lowrance innovation that uses sophisticated programming and advanced digital electronics to continually monitor the effects of boat speed, water conditions, and other interference sources - and automatically adjusts the sonar settings to provide the clearest picture possible.

ASP sets the sensitivity as high as possible while keeping the screen free of "noise." It automatically balances sensitivity and noise rejection. The feature can be turned off and on and will work whether the sonar is in automatic or manual mode. With ASP operating behind the scenes you’ll spend less time making routine sonar adjustments and more time spotting fish.

The sensitivity controls the ability of the unit to pick up echoes. A low sensitivity level excludes much of the bottom information, fish signals, and other target information. High sensitivity levels enable you to see this detail, but it can also clutter the screen with many undesirable signals. Typically, the best sensitivity level shows a good solid bottom signal with Grayline® and some surface clutter. When in the automatic mode, the sensitivity is automatically adjusted to keep a solid bottom signal displayed, plus a little more. This gives the unit the capability to show fish and other detail. In automatic mode, the unit also adjusts sensitivity automatically for water conditions, depth, etc. When you adjust the sensitivity up or down, you are biasing up or down the normal setting the unit’s automatic control would choose. With ASP enabled, the automatic mode picks the proper sensitivity level for 95% of all situations so it is recommend to always use this normal mode first. But, for those unusual situations where it is warranted you can bias it up or down. You can also turn off the automatic sensitivity control for special uses.

To properly adjust the sensitivity while the unit is in the manual mode, first change the range to double its current setting. For example, if the range is 0 - 40 feet, change it to 0 - 80 or 0 - 100 feet. Now increase the sensitivity until a second bottom echo appears at twice the depth of the actual bottom signal. This "second echo" is caused by the echo returning from the bottom reflecting off the surface of the water, making a second trip to the bottom and returning. Since it takes twice as long for this echo to make two trips to the bottom and back, it shows at twice the depth of the actual bottom. Now change the range back to the original scale. You should see more echoes on the screen. If there is too much noise on the screen, back the sensitivity level down a step or two.

Grayline lets you distinguish between strong and weak echoes. It "paints" gray on targets that are stronger than a preset value. This allows you to tell the difference between a hard and soft bottom. For example, a soft, muddy or weedy bottom returns a weaker symbol which is shown with a narrow or no gray line. A hard bottom returns a strong signal which causes a wide gray line.

If you have two signals of equal size, one with gray and the other without, then the target with gray is the stronger signal. This helps distinguish weeds from trees on the bottom or fish from structure.

Grayline is adjustable. Since Grayline shows the difference between strong and weak signals, adjusting the sensitivity may require a different Grayline level also.
The zoom feature enlarges all echoes on the screen.
You may see fish arches while trolling with the unit in a 0 - 60 foot scale, however it it much easier to see the arches when using the zoom feature. This enlarges all echoes on the screen. Turning the zoom feature on gives you a screen similar to the one at right. The range is 8 - 38 feet, a 30-foot zoom. As you can see, all targets have been enlarged, including the bottom signal. Fish arches (A & B) are much easier to detect, and important structure (C) near the bottom is magnified. This also shows small fish hanging just beneath the surface clutter (D). The above steps are all that’s required to manually adjust your sonar unit for optimum fish finding capability. After you’ve become more familiar with your unit, you’ll be able to adjust the sensitivity properly without having to look for a second echo.