Power On the Unit

Follow the instructions below to power on your Humminbird control head.

570 Title Screen

1. Press the

POWER/LIGHT key.

2. When the Title screen is displayed, press the MENU key to access the Start-Up Options Menu. 3. Use the 4-WAY Cursor Control key to select Normal (if there is a transducer attached to the control head) or Simulator (if there isnt a transducer attached to the control head).
NOTE: See Start-Up Options Menu for more information.
If a functioning transducer is connected, Normal operation will be selected automatically at power up, and your Fishfinder can be used on the water. If a transducer is not connected and you wait too long to select a Start-Up Option, the system will default to whichever menu is already highlighted. In Simulator you can learn how to use your control head and save settings in advance for later use. 1

How Sonar Works

Sonar technology is based on sound waves. The 500 Series Fishfinder uses sonar to locate and define structure, bottom contour and composition, as well as depth directly below the transducer. Your 500 Series Fishfinder sends a sound wave signal and determines distance by measuring the time between the transmission of the sound wave and when the sound wave is reflected off of an object; it then uses the reflected signal to interpret location, size, and composition of an object. Sonar is very fast. A sound wave can travel from the surface to a depth of 240 ft (70 m) and back again in less than 1/4 of a second. It is unlikely that your boat can outrun this sonar signal. SONAR is an acronym for SOund and NAvigation Ranging. Sonar uses precision sound pulses or pings which are emitted into the water in a teardrop-shaped beam. The sound pulses echo back from objects in the water such as the bottom, fish, and other submerged objects. The returned echoes are displayed on the LCD screen. Each time a new echo is received, the old echoes are moved across the LCD, creating a scrolling effect.
When all the echoes are viewed side by side, an easy to interpret graph of the bottom, fish, and structure appears.

The sound pulses are transmitted at various frequencies depending on the application. Very high frequencies (455 kHz) are used for greatest definition but the operating depth is limited. High frequencies (200 kHz) are commonly used on consumer sonar and provide a good balance between depth performance and resolution. Low frequencies (83 kHz) are typically used to achieve greater depth capability.
The power output is the amount of energy generated by the sonar transmitter. It is commonly measured using two methods: Root Mean Square (RMS) measures power output over the entire transmit cycle. Peak to Peak measures power output at the highest points. The benefits of increased power output are the ability to detect smaller targets at greater distances, ability to overcome noise, better high speed performance and enhanced depth capability. 3

Single Beam Sonar

The 550 Fishfinder and 560 Fishfinder use a 200 kHz single beam sonar system with a 20 area of coverage. Depth capability is affected by such factors as boat speed, wave action, bottom hardness, water conditions, and transducer installation.

DualBeam Sonar

The 570 Fishfinder uses a 200/83 kHz DualBeam sonar system with a wide (60) area of coverage. DualBeam sonar is optimized to show the greatest bottom definition using a narrow (20) beam yet can still indicate fish found in the wide (60) beam when the Fish ID+ feature is turned on. DualBeam is ideal for a wide range of conditions - from shallow to very deep water in both fresh and salt water. Depth capability is affected by such factors as boat speed, wave action, bottom hardness, water conditions, and transducer installation.
The 500 Series Fishfinder can display a variety of useful information about
Depth - Water depth; can be set to alarm when the water becomes too shallow.
Temperature - Water surface temperature. Timer - Elapsed time with Temp/Speed Accessory. Distance - Distance traveled with Temp/Speed Accessory. Average Speed - Average speed reading with Temp/Speed Accessory.
Second Sonar Return - When the sonar signal bounces between the bottom and the surface of the water and back again. Use the appearance of the second return to determine bottom hardness. Hard bottoms will show a strong second return, while soft bottoms will show a very weak one or none at all. Speed - If a Temp/Speed accessory is attached, the Fishfinder can display the speed of the boat and can keep a Triplog of nautical or statute miles traveled.
NOTE: Entries in this view that list (with Temp/Speed) are available if the accessory is connected
the area under your boat, including the following items:
Bait Ball Hollow Fish Symbol (83kHz, Wide Beam) Thermoclines - Layers of water with different temperatures that appear at different depths and different times of the year. A thermocline typically appears as a continuous band of gray levels moving across the display at the same depth. Structure - Where fish may be hiding. Fish - The Fishfinder displays fish as arches and/or fish icons, and can be set to alarm when a fish of a certain size is detected. When a target is detected, a Fish ID+ symbol appears on the display with the depth displayed above it. The size of the symbol indicates the intensity of the sonar return. The unit will clearly show schools of Bait Fish as "clouds" of different shapes and sizes, depending on the number of fish and boat speed. Shaded Fish Symbol (200 kHz, Narrow Beam) RTS (Real Time Sonar) Window Battery Voltage - The voltage of the boats battery; can be set to alarm if the voltage falls below a certain point.

Bottom Contour Profile with RTS Window

Hard Bottom

Soft Bottom Rocky Bottom
The sonar returns from the bottom, structure, and fish can be represented as Inverse, Structure ID, WhiteLine, or Black (Bottom Black). See Sonar XPress Menu: Bottom View to set the Bottom View.
Inverse is a method where weak returns are shown with dark pixels and strong returns with lighter pixels. This has the benefit of ensuring that weak signals will be clearly visible on the display.
Structure ID represents weak returns as light pixels and strong returns as dark pixels. This has the benefit of ensuring that strong returns will be clearly visible on the display.
WhiteLine highlights the strongest sonar returns in white resulting in a distinctive outline. This has the benefit of clearly defining the bottom on the display.
Black (Bottom Black) displays all pixels below the bottom contour as black, regardless of signal strength. This has the benefit of providing a high contrast between the bottom and other sonar returns on the display.

Sonar View

Sonar Zoom View

Accessory Test View

Self Test View

Big Digits View

The sonar information from your Fishfinder is displayed on the screen in a variety of easy-toread views. There are many views available on your Fishfinder. When you press the VIEW key, the display cycles through the available views on your screen. When you press the EXIT key, the display cycles through the available views in reverse order.
When you first power up the control head, Sonar View will be the default view. You can display and hide any view to suit your fishing preferences.
NOTE: When you change any menu settings that affect the sonar, the view will update immediately. You don't have to exit the menu to apply the change to the screen.

Sonar Views

Sonar View Sonar Zoom View Big Digits View Self Test View
(see Start-Up Options Menu)

Details about each view are available on the following pages.
To customize your view rotation: You can choose which views are hidden or visible in your view rotation. 1. Press the MENU key twice to access the tabbed Main Menu, then press the RIGHT Cursor key until the Setup tab is selected. 2. Press the DOWN Cursor key to highlight Select Views, and press the RIGHT Cursor key to access the Select Views submenu. 3. Press the UP or DOWN Cursor keys to select a View. 4. Press the LEFT or RIGHT Cursor keys to change the status of the view from Hidden to Visible or vice versa.
NOTE: If the Select Views option does not appear under the Setup tab, change the User Mode to Advanced.
To change the Digital Readouts: Each view displays digital readout information (such as speed or time), which varies with the view selected and the accessory attached. The digital readouts on the Sonar View can be customized. See Setup Menu Tab: Select Readouts for more information. 1. Press the MENU key twice to access the tabbed Main Menu, then press the RIGHT Cursor key until the Setup tab is selected. 2. Press the DOWN Cursor key to highlight Select Readouts, and press the RIGHT Cursor key to access the Select Readouts submenu.
NOTE: If the Select Readouts option does not appear under the Setup tab, change the User Mode to Advanced.
3. Press the UP or DOWN Cursor keys to select a Readout position, then press the RIGHT or LEFT Cursor keys to choose what will be displayed in that position. To hide the data window, select Off.
Sonar View presents a historical log of sonar returns. The most recent sonar returns are charted on the right side of the display. As new information is received, the historical information scrolls left across the display. Upper and Lower Depth Range numbers indicate the distance from the surface of the water to a depth range sufficient to show the bottom. Depth is automatically selected to keep the bottom visible on the display, although you can adjust it manually as well (see Sonar X-Press Menu). Digital Readouts shown on the display will change based on the Select Readouts settings or the optional-purchase accessories attached (see Setup Menu Tab: Select Readouts).
Depth Temperature Triplog Upper Depth Range

Sonar History Window

RTS Window

Lower Depth Range

NOTE: If the Depth number is flashing, it means that the unit is having trouble locating the bottom. This usually happens if the water is too deep, the transducer is out of the water, the boat is moving too fast, or for any other reason that the unit cant accurately receive continuous data.

POWER/LIGHT Key

The POWER/LIGHT key is used to power the Fishfinder on and off. You can also use the POWER/LIGHT key to adjust the backlight and contrast of the display. Power On the control head: Press the POWER/LIGHT key to power on the unit. When the Title screen is displayed, press the MENU key to access the Start-Up Options Menu. Power Off the control head: Press and hold the POWER/LIGHT key for 3 seconds. A message will appear to indicate how many seconds there are until shutdown occurs. To ensure that shutdown occurs properly and any menu settings will be saved, your Fishfinder should always be turned off using the POWER/LIGHT key. Adjust the Backlight or the Display Contrast: Press the POWER/LIGHT key to access the Light and Contrast submenu. Use the 4-WAY Cursor Control key to select Light or Contrast, and then use the LEFT or RIGHT Cursor key to change the settings. Press EXIT to exit the Light and Contrast submenu.
NOTE: Your 500 Series Fishfinder will start up with the backlight on and will automatically turn it off to conserve power.

VIEW Key

The VIEW key is used to cycle through all available views. Press the VIEW key to advance to the next view. Repeatedly pressing VIEW cycles through all views available. Views can be hidden to optimize the system to your fishing requirements (see Views or Setup Menu: Select Views).
NOTE: Press the EXIT key to cycle through the views in reverse order.

MENU Key

The MENU key is used to access the menu system. See The Menu System for more information. Start-Up Options Menu: Press the MENU key during the power up sequence to view the Start-Up Options menu. X-Press Menu: Press the MENU key once in any view to access the X-Press Menu, which provides frequently-used menu settings that correspond with the current view. Main Menu: Press the MENU key twice in any view to access the Main Menu, which is organized under tabbed headings to help you find a specific menu item quickly.

4-WAY Cursor Control Key

Use the 4-WAY Cursor Control key to navigate the Menu System. Menu Selection: Press the DOWN or UP Cursor keys to highlight a menu option, then press the RIGHT or LEFT Cursor keys to change a menu setting. The changes will be activated and saved immediately.

EXIT Key

The EXIT key has multiple functions, which depend on the situation: If an alarm is sounding, press the EXIT key to cancel the alarm. If a menu tab is selected, press the EXIT key to exit the menu mode and return to the view. If a menu is active, press the EXIT key to return to the previous level in the menu system. From any view, press the EXIT key to cycle through the available views in reverse order.

The Menu System

The Menu System is divided into easy-to-use menu modules as follows: Start-Up Options Menu: Press the MENU key during the power on sequence to view the Start-Up Options Menu. From the Start-Up Options Menu, you can choose the following Fishfinder Modes: Normal, Simulator, and System Status. X-Press Menu: The X-Press Menu provides a shortcut to the most frequently-used settings, and the options on the X-Press Menu correspond with the current view. Main Menu: The Main Menu is a standard set of menu settings which are organized under the following tabbed headings: Alarms, Sonar, and Setup.
NOTE: The X-Press Menu(s) and the Main Menu options can also be expanded or simplified by setting the User Mode to Advanced or Normal (see Main Menu: User Mode).

Start-Up Options Menu

Press the MENU key during the power on sequence to view the Start-Up Options Menu, and select one of the modes described on the following pages. Also, see Power on the Unit for additional information.

Normal

Use Normal for on-the-water operation with a transducer connected. If a functioning transducer is connected, Normal operation will be selected automatically at power up, and your Fishfinder can be used on the water. To exit Normal operation, power off your Fishfinder.

Simulator

Use Simulator to learn how to use your Fishfinder before taking your boat on the water. The Simulator is a very powerful tool that provides a randomly-updated display which simulates on the water operation.
We recommend going through this manual while using the Simulator, since all of the menus function and affect the display in the same way as they would in Normal operation. Any menu changes you make will be saved for later use.
NOTE: It is important to select Simulator manually from the Start-Up Options Menu as opposed to letting the Fishfinder enter Simulator automatically (as it will if a transducer is not connected and you do nothing during power up).
A message will appear often on the display to indicate Simulator mode. To exit Simulator, power off your Fishfinder.

System Status

Use System Status to view system connections and to conduct a unit self-test. After you select System Status from the Start-Up Options Menu, press the VIEW key to display the following options: Self Test Accessory Test To exit System Status, power off your Fishfinder.

Self Test displays results from the internal diagnostic self test, including unit serial number, Printed Circuit Board (PCB) serial number, software revision, total hours of operation, and the input voltage.

Self Test Screen

Accessory Test lists the accessories connected to the system.
System Status Accessory Test Screen
NOTE: The speed accessory will be detected only if the paddlewheel has moved since your Fishfinder was powered up.

X-Press Menu

The X-Press Menu provides a shortcut to your most frequently-used settings. The options provided on the X-Press Menu correspond with the current view. For example, if you are in a Sonar View and press the MENU key once, the Sonar X-Press Menu will display.
To use an X-Press Menu: 1. In any view, press the MENU key once. 2. Press the UP or DOWN Cursor keys to highlight an X-Press Menu option, then use the RIGHT or LEFT Cursor keys to change the menu setting.
NOTE: The X-Press Menu will collapse temporarily and the screen will update if it is affected by your menu setting change, which allows you to see the effects of your change immediately.
3. Reactivate the X-Press Menu by pressing the UP or DOWN Cursor keys. Total Screen Update - When you change any menu settings that affect the current view, the view will update immediately (i.e. you dont have to exit the menu to apply the change to the screen).
Menu options can be simplified or expanded by setting the User Mode to Normal or Advanced. See Main Menu: User Mode for details.

Main Menu

The Main Menu provides the standard set of menu options, including the settings that are changed less frequently. The Main Menu is organized under the following tabs to help you find a specific menu item quickly: Alarms, Sonar, and Setup.
NOTE: Menu options can be expanded or simplified by setting the User Mode to Advanced or Normal. See Main Menu: User Mode for details.
Main Menu (Normal User Mode)
To use the Main Menu: 1. In any view, press the MENU key twice. 2. Press the RIGHT or LEFT Cursor keys to highlight a menu tab. 3. Press the DOWN or UP Cursor keys to select a specific menu option under that tab. 4. Press the RIGHT or LEFT Cursor keys again to change a menu setting. A down arrow at the bottom of a menu means that you can scroll to additional menu options using the DOWN Cursor key. A right or left arrow on a menu option means that you can use the RIGHT or LEFT Cursor keys to make changes or to see more information. Press the EXIT key to move quickly to the top of the tab.
Total Screen Update - When you change any menu settings that affect the current view, the view will update immediately (i.e. you dont have to exit the menu to apply the change to the screen).

Quick Tips for the Main Menu
From any menu option on a menu tab, press the EXIT key to jump directly to the top of the tab. From the bottom of a menu tab, press the DOWN Cursor key to jump directly to the top of the tab. From the top of a menu tab, press the LEFT or RIGHT Cursor keys to scroll to the next tab. You can also jump to the beginning or end of the tab rotation by repeatedly pressing the RIGHT or LEFT Cursor keys. If there is a down arrow at the bottom of a menu tab, press the DOWN Cursor key to scroll to additional menu options. If there is a right or left arrow on a menu option, press the RIGHT or LEFT Cursor keys to make setting changes or see more information. If you press MENU or EXIT to leave the Main Menu and then return to the Main Menu at a later time, the menu will open to the same tab as the last time the Main Menu was displayed.
Note for all Menu Settings
The settings in all menus are adjusted in the same way. Simply use the 4-WAY Cursor Control key to highlight a menu option, and then change the settings or activate the option (see Main Menu or X-Press Menu). Below is an example of how the menu options are described in this manual. Each description shows the menu option appearance, the available settings, and the specific control head settings required (i.e. advanced user mode, international only, view, navigation, or accesssory).
Menu Option Name Setup User Mode and other control head requirements Available Menu Settings and Default Setting Description

Noise Filter

(Advanced)
Settings: Off, Low, Medium, High1, High2, High3, Default = Low
Noise Filter adjusts the sonar Noise Filter to limit interference on the display from sources such as your boat engine, turbulence, or other sonar devices.
Menu Option as it appears on the screen
User Mode (Normal or Advanced)
Menu options can be simplified or expanded by setting your Fishfinder User Mode to Normal or Advanced. Normal Mode is the default setting when you first power on your 500 Series Fishfinder. Normal mode is provided for users who want greater simplicity and fewer menu choices. Advanced Mode is provided for users who want the highest level of control over the Fishfinder. Several menu settings are added to the Main Menu when the User Mode is changed to Advanced. To change the User Mode setting: 1. Press the MENU key twice to access the Main Menu. 2. Press the RIGHT Cursor key until the Setup tab is selected. 3. Press the DOWN Cursor key to highlight User Mode on the Setup main menu. 4. Press the LEFT or RIGHT Cursor keys to change the User Mode setting. (Normal, Advanced, Default = Normal)

Off All Large/Medium Large

Low Battery Alarm

Settings: Off, 8.5V - 13.5V, Default = Off
Low Battery Alarm sounds when the input battery voltage is equal to or less than the menu setting. The battery alarm will only sound for the battery that is connected to the Fishfinder. The Low Battery Alarm should be set to warn you when the battery voltage drops below the safety margin that you have determined.
For example, if you are running a trolling motor (battery operated), you would want to set the Low Battery Alarm to sound before the battery voltage drops too low for it to be used to start your main, gasoline-powered engine.

Temp. Alarm

Settings: Off, 33-120 [Fahrenheit], 0-50 [Celsius], Default = Off
Temp. Alarm sounds when the water temperature detected by the Fishfinder reaches the Temp. Alarm setting, which is either set in degrees Fahrenheit or Celsius [International Models only].
For example, if the Temp. Alarm is set to 58 degrees Fahrenheit, and the water temperature falls from 60 degrees to 58 degrees, the Temp. Alarm will sound. Similarly, if the water temperature rises from 56 degrees to 58 degrees, the Temp. Alarm will also sound.

Alarm Tone

Settings: High, Medium, Low, Default = Medium
Alarm Tone selects the pitch of the alarm sound. A brief tone will be produced as you adjust the Alarm Tone so that you can select the tone that you can hear best.
Press the MENU key twice to access the Main Menu and then press the RIGHT Cursor key until the Sonar tab is selected.

Sonar Menu

Surface Clutter
Settings: Low = 1 to High = 10, Default = 5
Surface Clutter adjusts the filter that removes surface clutter noise caused by algae and aeration. The lower the setting, the less surface clutter will be displayed.
Settings: Clear Mode, Max Mode; Default = Clear Mode
SwitchFire controls how the sonar returns are displayed in the Sonar Views. Choose Max Mode to see only raw sonar returns on the display. When Max Mode is selected, you will see the maximum sonar information available within the transducer beam, so more fish arches and better jig tracking are shown. Choose Clear Mode to see less clutter and more fish size accuracy on the display. When Clear Mode is selected, the clutter is filtered, and sonar returns are interpreted to provide more details about the objects within the transducer beam, regardless of their location. In other words, a large arch on the display means a large fish has been detected.

Fish ID+

Settings: Off, On, Default = On
Fish ID+ uses advanced signal processing to interpret sonar returns and will display a Fish Symbol when very selective requirements are met. When a fish is detected, a fish icon and its depth are displayed above the return that has been classified as being a fish. Three different fish size icons represent the intensity of the sonar return and provide an indicator of relative fish size. DualBeam sonar models represent targets detected in the 200 kHz narrow beam as Shaded Fish Symbols and targets detected in the 83 kHz wide beam as Hollow Fish Symbols.

200 kHz, Narrow Beam Shaded Fish Symbols
83 kHz, Wide Beam Hollow Fish Symbols
When Fish ID+ is turned off, the Fishfinder shows only the raw sonar returns on the display. These returns will often result in arches forming on the display, indicating potential targets. Due to the transducer beam angle, the distance to a fish decreases as the fish moves into the beam, and then increases as it moves out again, creating a Fish Arch when this distance change is shown on the display. Boat speed, chart speed, and the position of the fish within the sonar beam greatly affect the shape of the arch.
Transducer Cone and Fish Arches

Fish ID Sensitivity

Settings: Low = 1, High = 10, Default = 5
Fish ID Sensitivity adjusts the threshold of the Fish ID+ detection algorithms. Selecting a higher setting allows weaker returns to be displayed as fish. This is useful for identifying smaller fish species or baitfish. Selecting a lower setting displays fewer fish from weak sonar returns. This is helpful when seeking larger species of fish. Fish ID Sensitivity is used in conjunction with Fish ID+. Fish ID+ must be On for Fish ID Sensitivity to affect the ability of the Fishfinder to identify sonar returns as fish.
Settings: Wide, Narrow, Off, Default = Narrow
RTS Window sets the RTS Window to either Wide or Narrow, or turns it off in the Sonar View. The RTS Window always updates at the fastest rate possible and only displays returns that are within the transducer beam. See Whats on the Sonar Display for more information.
NOTE: The Wide RTS Window does not use grayscale.
RTS Window (Wide) RTS Window (Narrow) RTS Window (Off)

Zoom Width

Settings: Narrow, Medium, Wide, Default = Wide
Zoom Width adjusts the width of the zoomed view on the Sonar Zoom View, which is on the left side of the display. See Views: Sonar Zoom View for more information. 39

Depth Lines

Depth Lines divide the display into four equal sections which are separated by three horizontal depth lines. The depth of each line is displayed along the depth scale. You can turn Depth Lines On or Off.
Noise Filter adjusts the sonar Noise Filter to limit interference on the display from sources such as your boat engine, turbulence, or other sonar devices. The Off setting removes all filtering. Low, Medium, and High1, High2, High3 settings add progressive filtering of the sonar returns. High1, High2, and High3 are useful when there is excessive trolling motor noise, but in some deep water situations, the High settings may actually hinder your units ability to find the bottom.

Max Depth

Max Depth controls the maximum depth of operation. When Max Depth is set to Auto, the Fishfinder will acquire bottom readings as needed (within the capacity of the unit). When Max Depth is set to match your fishing maximum depth, your Fishfinder will not attempt to acquire sonar data below that depth, so more detail will be shown on the screen.

Triplog Reset

Settings: Follow screen instructions to activate.
Triplog Reset resets the Triplog to zero, and will appear in the menu if a Temp/Speed Accessory is connected and the paddlewheel has moved at least once. The Triplog provides the following information: timer for elapsed time, distance traveled since last reset, and average speed.
NOTE: See Views to find out how to display Triplog information on the screen.

Restore Defaults

Use this menu choice with caution! Restore Defaults resets ALL menu settings to their factory defaults.

Select Views

Settings: Visible, Hidden, Default = Visible
Select Views allows you to set the available views to either hidden or visible in the view rotation. The view will be removed from the view rotation if it is set to Hidden and will be displayed in the view rotation if it is set to Visible.
NOTE: See Views for more information.

Select Readouts

(Advanced, Sonar View only)
Settings: Various, Default = Off
The readout position on the screen is shown in the Select Readouts Window.
Select Readouts sets the information to display in each of the 6 fixed-position data windows arranged around the left and bottom edges of the Sonar View screen. To leave the data window blank, select Off. See Views to change the Select Readouts. Data windows can display readouts from supported accessories such as Temp/Speed. Each data window can be empty or contain one of the following information categories:
Speed Temperature Triplog Voltage 45
NOTE: The availability of the digital readout information corresponds with the view selected and the accessory attached.

Default Sonar View

Sonar View with Select Readouts

Depth Offset

Settings: -10.0 to +10.0 ft or -3 to 3 m [International Models only], Default = 0
Depth Offset will adjust the digital depth readout to indicate depth from the waterline or boat's keel. Enter a positive vertical measurement from the transducer to the waterline to read the depth from the waterline. Enter a negative vertical measurement from the transducer to keel to read the depth from the keel.

Glossary

Sonar Terms: Beam (Sonar Beam) The wide, cone-shaped projection of sound waves formed as sound
travels underwater. See Cone Angle.
Bottom Contour The profile of the bottom graphed to the display as the depth changes. Bottom Hardness The density (or composition) of the bottom. Varying levels of hardness
can be determined by interpreting the thickness of the main sonar return. Hard returns appear thin and black, softer returns appear thicker and less black. It is important to note that a sonar return from a sloping bottom can have the appearance of a softer bottom.
Cavitation The effect of air bubbles created as the propeller rotates and the boat moves

through the water.

Cone Angle The angular measurement of the sonar beam at a specific dB down point
(i.e. -10 dB). See dB Down Point.
Dead Zone The area of the sonar beam that receives the sonar signal after the main
bottom return. Fish and other objects close to the bottom that fall within the dead zone will probably not be visible in the sonar beam. Precision sonar beams, such as the Humminbird 20 beam, have a smaller dead zone than wider sonar beams.
Decibel The measurement for sound pressure level, or intensityof the sonar return. See dB Down Point. dB Down Point The standard decibel level at which the sonar cone angle is measured,
and is written as @ -10 dB or @ -3 dB. Measurements at smaller down points (bigger negative numbers) indicate that the less intensive sonar signals are being used for the measurement.
Display, FSTN (Film Super-Twist Nematic) FSTN is a monochrome display technology
characterized by black, high-contrast pixels. All monochrome fixed mount Humminbird products use FSTN technology.
Frequency A measure of the number of sound wave cycles per second of a sound impulse
transmitted underwater. A typical frequency for fishfinders is 200 kHz, which offers a good balance of performance under many conditions. Lower frequencies, such as 50 kHz, are capable of penetrating to greater depths, but with less resolution. Higher frequencies, such as 455 kHz, offer greater resolution, but are limited in depth performance. Humminbird uses a variety of frequencies that are optimized for specific applications.

Grayscale The use of varying shades of gray to represent the strength of the sonar signal
on the display. Traditionally, the strongest sonar signals are represented in black, and progressively weaker signals are represented in progressively lighter shades of gray.
Noise The unintentional, external sound waves that interfere with the optimal operation
of sonar. Noise appears as random dots on the display and is caused by a variety of sources. Many Humminbird products have a Noise Filter menu setting that allows the user to clear the screen of noise that is difficult to eliminate (also, see Troubleshooting).
Pixels The picture elements, or small square blocks, that make up the image on the LCD.
Measured as a vertical by horizontal number (i.e. 640V x 320H), this key specification typically indicates the quality of resolution. In fishfinders, the total resolution (vertical multiplied by horizontal) is often less important than the Vertical Pixel resolution because a greater number of vertical pixels provide finer resolution of targets detected by sonar. Sonar information on the horizontal axis can vary greatly, depending on boat speed and the Chart Speed setting.
Power Output The amount of sound energy emitted into the water by the transducers
transmitter. Power output is measured using either RMS (Root Mean Square) or P-T-P (Peakto-Peak) measurement systems. Either method is acceptable, but it is important when comparing power outputs, to make sure that the same measurement system is being used for both outputs, because P-T-P numbers are 8 times higher than RMS numbers. Greater power output allows the sonar signal to penetrate through weeds and thermoclines, reach deeper depths and operate more effectively in noisy environments, such as when the boat is running at high speed.
Pulse Width (Pulse Length) The length of time that a sonar sound burst is transmitted
into the water. Shorter pulse widths provide better target separation, but cannot travel to great depths. Longer pulse widths provide better depth penetration, but result in poorer target separation. Humminbird varies pulse width based on depth to optimize both target separation and depth performance. See Target Separation.
Second Return Describes the appearance of a second sonar return below the primary
sonar return (bottom contour) at exactly twice the true depth. The second return is caused by the same sonar energy bouncing off the bottom once, rebounding to the water surface and then traveling back down to the bottom to be reflected again. Second returns are more common in shallow water and over hard bottoms; it is possible to see a third sonar return under some circumstances. The second return provides useful information to help determine bottom hardness, as areas with harder bottoms will generally create a second return. The second return can be used as a guide to set Sensitivity when in shallower water.