531524-1_A - 717 & 727 Man_Eng.qxp 9/30/2006 7:23 PM Page 7

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.

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Humminbird manual 531524-1A 717 & 727 ManEng.qxp 9/30/2006 723 PM