Feature Memory: Feature Memory is a H umminbird® feature that retains the user’s menu settings in permanent memory. Settings are retained even when the unit is powered offindefinitely.

Fish Arch: A Fish Arch is the apparent “arch“ that appears on the display when any obj ect m oves t hrough the s onar co ne. Th e a rch 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, anarch appears.

Fish ID+™: Fish ID+™ is a Humminbi rd® feat ure that uses advan ced sonar processing algorithms to determine fi a detected object is likely to be a fish. When the sonar signal from an obj ect 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 a re shown a s 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 Humm inbird® feature that pauses the sonar scrolling so that t he image on s creen can be stu died with greater detail. See Instant Image Update.

Frequency: Frequency is a measure of the n umber of sou nd wave cycles per second of a sound i mpulse transmittedu nderwater. A ty pical frequency for fishfinders is 200 kHz, which offers a good balance of performance under many conditions. L ower f requencies,s uch as 50 kHz , are capable o f penetrating to greater depths, but with less resolution.Higher frequencies, suchas 455 kHz, offer greater resolution, but are limited in de pth performance. Humminbird® uses a variety of frequencies that are optimizedfor specific applications.

Grayscale: Grayscale is the use of varying shad es of gr ay to r epresent the strength of the s onar signal on the disp lay , and is a very intuit ive method of

presenting info rmation. Tr aditionally, t he strong est sona r sig nals are represented in b lack, and progr essively weak er signa ls a re repr esented in progressively lighter shades of gray.

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Glossary