Author Topic: Humminbird Glossary - Sonar Terms  (Read 11772 times)

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Offline RGecy

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Humminbird Glossary - Sonar Terms
« on: May 21, 2009, 05:27:33 PM »
Glossary - Sonar Terms

Alarm, Depth: Depth Alarm is a user-controllable, audible alert that sounds when depth is less than or equal to the setting.

Alarm, Temperature: Temperature Alarm is a user-controllable, audible alert that sounds when the water surface temperature equals the setting.

Backlight: Backlight is a user-controllable illumination for the LCD for night and low light use.

Beam (Sonar Beam): A sonar beam is the wide, cone-shaped projection of sound waves formed as sound travels underwater. See Cone Angle.

Big Digits View: Big Digits View is a Humminbird® feature that displays the sonar graph and enlarged digital readouts for easy reading from a distance. This is a great tool when monitoring the digital depth is important - such as with higher boat speeds, or when viewing the unit from a distance. When speed input is available, the Big Digits View also shows the TripLog. See TripLog.

Bottom Black: Bottom Black is a Humminbird® feature that "fills in" the area of the display below the bottom contour. Bottom Black is preferred by some anglers because of its high contrast and easy readability, even though it can obscure bottom hardness information.

Bottom Contour: Bottom Contour is the profile of the bottom graphed to the display as the depth changes.

Bottom Hardness: Bottom Hardness is the density (or composition) of the bottom, which can often be determined by interpreting the main sonar return. Varying levels of hardness can be determined by interpreting the "thickness" of the 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: Cavitation is the effect of air bubbles created as the propeller rotates and the boat moves through the water.

Chart Speed: Chart Speed is a user-controllable feature that sets the speed at which sonar information moves across the display. A faster setting displays sonar information from more pings and shows more detail, but the information moves quickly across the display: a slower setting permits viewing of more sonar history, but does not display as much detail. The best setting is often the user's personal choice. 

Cone Angle: The cone angle is the angular measurement of the sonar beam at a specific dB down point (i.e. -10 dB). See dB Down Point.

Customizable Digital Readouts: Customizable Digital Readouts is a Humminbird® feature that permits the user to select the specific digital information that appears in the main Sonar view (i.e. Speed, Temperature, Barometric Pressure, TripLog, etc.)

Dead Zone: The dead zone is 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: A Decibel is the measurement for sound pressure level, or "intensity" of the sonar return. See dB Down Point.

dB Down Point: The dB Down Point is 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: FSTN is an acronym for 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.

DualBeam PLUS™: DualBeam PLUS™ is a Humminbird® sonar configuration that uses two sonar beams simultaneously, and combines the information from both beams into one view by overlapping the data on-screen, or shows each beam individually side by side, or permits each beam to be viewed individually full screen.

Feature Memory: Feature Memory is a Humminbird® feature that retains the user's menu settings in permanent memory. Settings are retained even when the unit is powered off indefinitely.

Fish Arch: A Fish Arch is the apparent "arch" that appears on the display when any object moves through the sonar cone. The arch results from a gradual decrease in distance to an object as it moves into the sonar cone. The distance to an object changes due to the conical shape of the sonar beam, which causes the distance to be greater at the edges of the beam than at the center of the beam. When this distance change is graphed on the display, an arch appears.

Fish ID+™: Fish ID+™ is a Humminbird® feature that uses advanced sonar processing algorithms to determine if a detected object is likely to be a fish. When the sonar signal from an object meets strict parameters, the unit draws a Fish Symbol (or icon) and the digital depth of the target. On DualBeam and DualBeam PLUS™ units, fish detected in the narrow center beam are shown as shaded symbols, and fish detected in the wider beam are shown as hollow symbols.

Fish Symbol: A Fish Symbol is the graphic that is displayed on the screen when Fish ID+™ determines that a sonar return is likely to be a fish. See Fish ID+™.

Freeze Frame: Freeze Frame is a Humminbird® feature that pauses the sonar scrolling so that the image on screen can be studied with greater detail. See Instant Image Update.

Frequency: Frequency is 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: Grayscale is the use of varying shades of gray to represent the strength of the sonar signal on the display , and is a very intuitive method of presenting information. Traditionally, the strongest sonar signals are represented in black, and progressively weaker signals are represented in progressively lighter shades of gray.

Grayscale, Inverse: Inverse Grayscale is a Humminbird® feature that reverses the correlation of sonar signal strength and the shade of gray typically used to represent it. The strongest sonar signals are represented by "white", and progressively weaker signals are represented in progressively darker shades of gray. While somewhat counter-intuitive, this method makes the sonar images crisper, and has the benefit of enhancing the apparent sensitivity because the weaker signals appear bolder. Inverse grayscale works well in very clear water. Debris-laden water often appears as a lot of clutter on the screen.

Instant Image Update: Instant Image Update is a Humminbird® feature that updates all the sonar information on the display when Sensitivity and a variety of sonar settings (Bottom View, Range, etc.) are modified. This differs from the traditional functionality that only updates the new sonar information collected after the setting change. Instant Image Update permits more accurate fine-tuning of the display because the user can see the results on the complete sonar graph. When combined with the Freeze Frame feature, the user can adjust and understand the effects of many different sonar settings quickly and easily.

Maximum Depth Menu: The Maximum Depth Menu is a Humminbird® feature that optimizes performance based on the maximum operational depth set by the user. Many Humminbird® units can operate across a very broad depth range (up to 2500 feet) which causes the unit to "look" up to that full depth under some circumstances. Due to the speed of sound in water, this can result in less responsiveness because the unit has to wait for a longer period of time to receive the sonar signal. When the Maximum Depth menu is set to a lower value, the unit only looks up to the setting, which increases the responsiveness of the unit. This is an important feature for anyone operating in shallower depths!

Noise: Noise is 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. Electrical noise (from trolling motors, bilge pumps, VHF radios) typically manifests as a consistent dot pattern. Electrical noise can be isolated by selectively turning on and off other electrical devices to determine the source. Often re-routing the power cable, or connecting to an alternative power supply (second battery) can help overcome electrical noise. Hydrodynamic noise (from propeller and/or hull cavitation) has a more random appearance and is generally related to boat speed, so that faster operation results in more noise. Hydrodynamic noise can be overcome by proper transducer installation. Many Humminbird® products have a Noise Filter menu setting that allows the user to clear the screen of noise that is difficult to eliminate.

Pixels: Pixels are the "picture elements", or small square blocks, that make up the image on the LCD. Measured as a vertical by horizontal number (i.e. 640 V x 320 H), 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. See Pixels, Vertical.

Pixels, Vertical: Vertical Pixels are a number of vertical picture elements in a single column on an LCD display. A greater number of vertical pixels provide finer resolution of targets detected by sonar. Essentially, a vertical distance (the depth), when divided by a larger number, breaks that distance into smaller samples, each representing a smaller area and thus providing more detail. In fishfinders, vertical pixels are more critical than horizontal pixels because the horizontal axis of the display represents time, or history. Sonar information on the horizontal axis can vary greatly, depending on boat speed and the Chart Speed setting. A greater number of horizontal pixels show more sonar history that the boat has passed through. On many models, Humminbird® provides the most vertical pixels to provide a better display resolution. See Chart Speed and Pixels.

Power Output: Power output is the amount of sound energy emitted into the water by the sonar transmitter. Power output is measured using either RMS (Root Mean Square) or P-T-P (Peak-to-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): Pulse Width is 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.

QuadraBeam PLUS™:[/color][/b] QuadraBeam PLUS™ is a Humminbird® sonar configuration that uses four sonar beams for a more detailed bottom image. QuadraBeam PLUS™ uses the DualBeam PLUS™ configuration for downlooking, and also adds two additional beams to look to the left and right. The sonar beams pointing to the left and right provide the ability to spot fish and structure over a wide 90° area, and to identify on which side of the boat they are located. See DualBeam PLUS™.

Quick Disconnect Mount: The Quick Disconnect Mounting system is an exclusive Humminbird® feature that permits the unit to be easily removed from the mounting base by pressing a release button, and re-installed by simply snapping it back into place. All cable connections are made when installing, so that no separate wiring connections are required. Additionally, the mount offers 90° tilt and 360° swivel capability to adjust the viewing angle of the unit as you move about the boat.

Real Time Sonar: Real Time Sonar is a Humminbird® technology that delivers ultrafast sonar transmitter/receiver operation and results in a more detailed instantaneous view of what is under the boat. The Real Time Sonar window is a vertical band at the right side of the display that shows the instantaneous sonar return from the transducer at a particular instant. The RTS® Window menu option permits the user to adjust the window to show the full sonar signal return, or just a narrower band that indicates intensity using grayscale. Real Time Sonar relies on very fast Sonar Update Rate (Ping Speed). See Sonar Update Rate.

Receiver: See Transmitter.

Second Return: The Second Return is a term that 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 actually 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.

Sensitivity: Sensitivity is a user feature that adjusts the sensitivity of the sonar system to show more or less detail in the water. Higher sensitivities are often preferred, however, when the water contains debris (silt, storm debris, etc.) and it can be difficult to pick out targets. Conversely, if sensitivity is set too low, relevant targets may be missed.

SONAR: SONAR is the acronym for SOund and NAvigation Ranging. Sonar technology uses precision sound bursts transmitted underwater to determine the distance and other attributes of objects in the water. Distance can be determined because the speed of sound in water is constant, and the time for the signal to return is measured. Sound also travels very quickly underwater, making sonar a responsive, cost-effective tool. Sonar is the basic technology behind all recreational and commercial fishfinding and depthfinding devices.

Sonar Echo Enhancement: Sonar Echo Enhancement is a Humminbird® feature that describes the high degree of sonar sensitivity achieved through a combination of transmitter/receiver and software algorithms. The result of Sonar Echo Enhancement is to display virtually everything in the water that is of interest to the angler, including bait fish, game fish, thermoclines, weed beds, subtle structure, and more.

Sonar Update Rate: Sonar Update Rate is the number of times per second that the transmitter/receiver sends and receives sonar signals. A very fast sonar update rate collects more information and provides a more detailed image of the bottom, fish and structure. Many Humminbird® units operate at up to 40 times per second when in single frequency operation. Due to the limitation of the speed of sound in water, the update rate begins to slow as depth increases to deeper than 50 feet. In very shallow water (less than 10 feet), however, update rates as much as 60 times per second can be achieved.

Speed: Speed is the rate at which the boat moves through the water. Boat speed can be measured as Speed Over Ground or Speed Through Water. Speed Over Ground is provided by GPS, and is the measurement of the boats progress across a given distance. Speed Through Water is provided by a speed paddlewheel, and is the measurement of the flow past the boat, which may vary depending on current speed and direction. Speed Through Water is most critical for anglers using downriggers, as it impacts the running depth of the down riggers. Speed Over Ground is optimal for navigation, as accurate destination times can be derived from this measurement. Humminbird® products allow for input and display of both sources.

Structure: Structure is a general term for objects on the bottom that present a discontinuity and are a likely attractor for fish. This includes bottom contour features (drop-offs, humps, and holes), standing structure (stumps, timbers, brush piles) and a wide range of other potential objects (sunken boats, reefs). Humminbird® units excel at showing structure with great detail over a wider area due to unique sonar configurations developed for the angler.

Structure ID®: Structure ID® is a Humminbird® feature that describes the traditional grayscale method of presenting sonar information. See Grayscale.

Surface Clutter: Surface Clutter is a phenomenon where sonar returns are reflected off of tiny objects near the surface of the water, including algae and even air bubbles. Typically, saltwater environments have significantly greater surface clutter than freshwater due to continuous wind and wave action that causes aeration at the surface. The Surface Clutter menu provides manual control to bias the default settings under extreme conditions.

Target Separation: Target Separation is the measurement of minimum distance that a fishfinder needs to be able to recognize two very close objects as two distinct targets (i.e. two fish hanging very close, or a fish hanging very close to structure). Humminbird® fishfinders provide a very good 2 1/2 inches of target separation in shallower than 100 feet of depth. Target separation decreases as depth increases due to the need for longer Pulse Width to achieve greater depth. See Pulse Width.

Thermoclines: Thermoclines are water layer(s) of distinctly different temperatures that create a sonar reflection due to the density of the differing water temperatures. Typically a thermocline will appear as a continuous band across the display at some distance above the bottom contour. Thermoclines are of interest to anglers because fish will suspend above or below the thermocline as they seek the optimum temperature and oxygen levels.

Time Variable Gain: Time Variable Gain is a processing step applied to the sonar return to "normalize" the data so that objects of equal size (i.e. fish) appear to be the same size, even if they are separated by a good distance. Time Variable Gain is a fundamental attribute of good sonar, but is often promoted as a feature. Total Screen Update®: A Humminbird® feature that refreshes and updates all the sonar information on the display when a range change occurs. Without Total Screen Update®, only the most recent sonar information would be drawn to the new range, and the old sonar information would continue to scroll off the screen at the old range.

Transducer: The transducer is part of the sonar system, which mounts on the boat and is in contact with the water, that converts the electrical energy from the transmitter into sound energy, and that forms the sonar beam in turn. Internally, the transducer consists of one or more piezo electric disks that expand by very minute amounts to create the sound wave. This element also works in reverse, converting the returned sound energy back into an electrical signal that the receiver interprets. Transducers are available for many specific mounting applications for the boat, such as a transom mount, trolling motor mount, etc. Humminbird® offers many sophisticated transducers, often with multiple piezo electric elements designed to form specifically-shaped sonar beams, providing the angler with superior tools for finding and catching fish. See Transmitter and SONAR.

Transmitter: The transmitter and receiver are matched parts of the sonar system that send (transmit) and listen to (receive) the sonar signals, and work in conjunction with the transducer. Humminbird® transmitters have an extremely fast cycling design that can send signals up to 60 times per second, as well as produce the varying levels of power output needed for different depths and conditions.  Additionally, the transmitter has the capability to create very precise sonar pulses needed for a high degree of target separation. Humminbird® receivers are extremely sensitive, but within a narrow "bandwidth" to discriminate against noise from external sources. Additionally, the receiver offers a wide "dynamic range" which provides the ability to receive very strong signals alternating with very weak signals, without the strong signal overwhelming the weak signal. See Transducer and Noise.

TripLog: TripLog is a Humminbird® feature that provides an on-screen counter for Elapsed Time, Average Speed and Total Distance traveled, and requires a speed input to activate the feature. TripLog appears on the Big Digits View, and can be reset to zero through the TripLog menu.

TrueArch®: TrueArch® is a Humminbird® feature that provides true fish arches, not artificial arches or symbols. Humminbird® units are capable of producing fish arches due to the wide 60° sonar beam of DualBeam PLUS™, an extremely sensitive sonar receiver. See Fish Arch.

Viewing Angle: Viewing Angle is an attribute of an LCD that characterizes visibility of the display when viewing from off the central access, such as when standing to the side of the fishfinder. Wider viewing angles are better because the information remains visible even when viewing from the side.

WhiteLine®: WhiteLine® is a Humminbird® feature that highlights the strongest sonar return on the display using a very light gray band. This is preferred by some anglers who have grown accustomed to the feature on paper graph chart recorders.

WideSide®: WideSide® is a Humminbird® sonar configuration used in an optional transducer. WideSide® uses three sonar beams pointing to the left, right and down. Beams pointing to the left and right are effective for spotting fish and structure near the surface or on the bank. The downlooking beam provides depth information directly below the boat.

X-Press™ Menu: X-Press™ Menus are a Humminbird® feature that make the most commonly-used menu selections available with one press of the MENU key. Items that appear on the X-Press™ Menu are related to the current view, and present the most logical choices for that view. Sonar View X-Press™ menus will differ from Chart View X-Press™ menus, etc. X-Press™ menus are one of the principal reasons that Humminbird® products are easier to use.

Zoom: Zoom is a feature that focuses in on a smaller area of the bottom to provide enhanced resolution. With enhanced resolution, the angler can more easily see fish hanging in structure or multiple fish hanging close together. Split screen zoom divides the display into the full range view on the right, and the zoomed view on the left. Humminbird® offers One-Touch® Zoom which allows the zoom feature to be easily accessed from the regular sonar view with just one key press, eliminating the need to use menus to access the feature.

Zoom, Bottom Lock: Bottom Lock Zoom is a feature that focuses on a smaller area just above the bottom to provide enhanced resolution. Unlike regular zoom, it continuously graphs the bottom at a constant point on the display regardless of changes in depth. This "flattens" out the bottom contour, but is effective at showing fish on or near the bottom, and is preferred by many saltwater anglers.
« Last Edit: August 18, 2011, 10:00:16 PM by RGecy »
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