Fish - Depth Finder Glossary of Terms.


See the Newest Lowrance fishfinder the HDS12 Gen 2 -  You can see the relation of the fish to the branches on the brush.

Fish Finders Installing a Fish Finder  Fish Finder Basics    Questions & Answers About Fish Finders



Acquisition Time:
The time it takes for your GPS to acquire a fix on your position.

Actual Sonar Returns
The targets you get displayed as arches on your screen when the Fish I.D. is turned off.

Advanced Fish Symbol I.D.â„¢
Part of the Lowrance system which when turned on automatically interprets sonar echoes and displays them as fish symbols. Also known as Fish I.D.

Advanced Signal Processing (ASPâ„¢)
Component of the Lowrance system which automatically fine tunes your sonar settings for clarity and accuracy. ASPâ„¢ is a noise rejection system that evaluates and constantly adjusts for speed, water conditions and interference. It takes into account equipment like bilge pumps, engine ignition, wiring and air bubbles on the transducer. Reducing unwanted marks on the display.

The sounds you hear so you don't have to keep looking at the screen. These can be turned on or off or set for certain events. Usually 3 different sonar alarms, Fish Alarm, Zone Alarm and Depth Alarm. Of course if the fish alarm goes off its reading an echo of a fish (Maybe) It will sound on other echos. The Zone Alarm is a bar on the side of the screen and any echo inside the bar triggers an alarm. The depth alarm goes off if your current position is outside the shallow or deep setting you have selected.

Height above sea level.

Top of Fish Finder Glossary


Illumination of screen best at night or in low light.

Bearing (BRG)
The exact compass direction from where you are to the next waypoint.


Turbulence which creates air bubbles around your transducer. The signal from the transducer is then reflected back and creates noise which interferes with your echoes making it impossible or difficult to see fish, bottom and structures.

Chart Speed
Speed at which your picture scrolls across the screen.

Compressed High Intensity Radar Pulse

Actual time it is.

Cold Start
Time it takes the GPS receiver to power up, search and lock onto the satellites. This may take some time because it is looking for your approximate present position, local time and date.

Lowrance component that separates fish and structures on or near the bottom from the actual bottom.

Course Deviation Indicator
Shows you your distance to the side of the actual course line.

COG - Course Over Ground
Current direction you are actually travelling.

Cross Track Error (XTE)
Digital reading on your GPS steering screen indicating exactly how far you are off course from the center.



Differential GPS (DGPS)
The international maritime standard created by the U.S. Coast Guard to improve GPS accuracy to 10 meters. Requires and added beacon receiver to communicate with the standard GPS unit.

Distance (DIS)
Distance remaining between your present position and a waypoint.

Distance To Go (DTG)
Indicates in a digital readout the remaining distance from your present position and a waypoint.


Estimated Position Error (EPE)
A calculation using geometry, satellite position, time clock offset, satellite signal quality and more to estimate the accuracy of your positon.

Estimated Time En-Route (ETE)
Using your speed and direction a calculation is made to estimate the time to the next waypoint or pre-selected waypoint.

Event Marker
Using an icon, a graphic symbol is placed on the display to represent an interesting event to be reviewed at a later time.



FasTrackâ„¢ (Lowrance)
A standard feature which displays flasher-style sonar in a vertical column on the right of the screen.

Film SuperTwist
The technology used by Lowrance on their Liquid Crystal Display. It provides excellent screen reading in direct sunlight, backlighting at night and from any angle.

Fish Arches
The boomerang shapes displayed on your screen which indicate fish.

Fish Symbol I.D.â„¢ (Lowrance)
See Advanced Fish Symbol I.D.  TURN THEM OFF!!! You will see a better representation of what's really under you if you don't use fish symbols.

Fish I.D.â„¢ (Humminbird)
When a target is detected and Fish ID is on a Fish ID+ symbol with depth is displayed. The size of the symbol shows the strength of the sonar return.

Fish Revealâ„¢ (Lowrance)
10 adjustable levels of gray tones to help you expose fish in surface debris, thermocline and weed beds when using actual sonar returns.

Fish Trackâ„¢ (Lowrance)
You have to have the Advanced Fish I.D.â„¢ and Fish Trackâ„¢ on for this to work. It gives the displays the digital depth above each fish symbol.

A quality measurement of your receiver's position. 1 is poor, 9 is good.

Combination of scrolling sonar graph, digital LCD flasher and GRAYLINE® or COLORLINE™. It puts all the information on your screen in the two most popular formats.

A floating transducer used when fishing from shore.



Global Positioning System (GPS)
Owned and operated by the U.S. Department of Defense and is a set of satellites orbiting the earth allowing people to pinpoint their location.

Grayline® (Lowrance)
Patented feature used to distinguish between hard and soft bottoms.

Ground Speed (GS)
Actual speed you are moving in a certain amount of time.


Locates and displays fish at higher boat speeds with more soundings per second.


A graphic symbol placed on the plotter screen to mark an interesting event.

The procedure that occurs when the new GPS receiver is turned on for the first time.






Magnetic North
The location your compass points. It is located in Canada, several hundred miles to the south of the true north.

MGRS (Military Grid Reference System)
An alphanumeric version of a numerical Universal Transverse Mercator grid coordinate.

Man Overboard


Visual clutter that appears on the display caused by unwanted signals being picked up by the fish finder.


Output Power
The electrical energy applied to the transducer by the sonar transmitter.



Parallel-Channel Receiver
Your GPS tracks multiple satellites to give you the fastest, most reliable, accurate information under the worst weather conditions.

Peak to Peak
Describes the output power of your sonar transmitter.

Active sonar creates a pulse of sound, often called a "ping", and then listens for reflections (echo) of the pulse. The PING works by transmitting an ultrasonic (well above human hearing range) burst and providing an output pulse that corresponds to the time required for the burst echo to return to the sensor. By measuring the echo pulse width the distance to target can easily be calculated.

Ping Speed
Ping Speed controls the rate at which the transmitter and transducer sonar sound waves -- Pings --- into the water.

Pixels or "picture elements"
Are colored or gray dots that form shapes on a liquid crystal display the more the better.

Plotter Display
Using your waypoints and markers your given a "bird's eye view" of your current position and the shortest route to a chosen waypoint.

Present Position
Where you are now in terms of latitude and longitude coordinates, displayed in degrees/minutes/thousandths of a minute.

Pulse Length
The amount of time the sonar transmits a pulse into the water.




Root Mean Square

The combination of two or more waypoints.


The manual way to adjust your fish finder. The Advanced Signal Processing (ASPâ„¢) does this automatically.

Sensors you can digitally display surface water temperature, boat speed and distance.

All solid objects rising from the bottom that aren't part of the actual bottom.



Areas where layers of warm water meet cool water.

Time To To (TTG)
A digital reading showing the time left from where you are now to the next waypoint.

Track (TRK)
The direction you are travelling.

The Main sensor that sends out sound waves and receives echoes that get displayed on the screen. An improperly installed transducer will give you nothing but problems. The transducer surface (face) must remain in contact with the water at all times. It will not transmit or receive thru air.
Air bubbles across the surface will also distort readings, therefore it is best to avoid placement near hull ribs and thru-hull fittings. The best position is located where the hull and transom meet and as near to the center of the transom as allowed.
 Basically there are two types of transducers a 50 khz and a 200khz.

True North
The top of the world and is not to be confused with magnetic north.


Coordinated Universal Time. Time at the Prime Meridian at Greenwich, England.

Universal Transverse Mercator



Your battery voltage running your fish finder. Most fish finders quit or erratically work when voltage drops below 9 volts.


A spot, destination or location that can be stored in device memory which can be recalled at a later date.

Wide Area Augmentation System is a satellite navigation system designed by the U.S. Federal Aviation Administration to increase the accuracy of GPS satellite navigation. It was originally created for aviation applications and because of satellite configuration you may experience a loss of signal in North America.




Feature that allows you to enlarge the sonar or gps map display for a closer look at the details.

Top of Fish Finder Glossary

Click to visit

Privacy Notice  I   Striper Links I   Glossary of Fish Terms 

Arkansas Parks and Tourism
Take a Kid Fishing
  |  Striper Fishing  Waters in Arkansas  |  Arkansas Record Striper
Striper Recipes
   |      Fishing Tackle


Ben Sanders'

Arkansas Striper Site Map

Striper Pictures

Striper Facts

Striper Boats

Live Wells for Stripers

Live Shad for Stripers

Catch and Release Can Kill Stripers

Fishing Line

Striper Age Weight Chart


Bait Tanks

Cast nets

Best Times To Catch Stripers

Striper Seasons


The National Striped Bass Association:

Search the Outdoors


Local Fishing "Slang"

Morone saxatilis

  Depth / Fish Finders