Humminbird 737 - Manual (Page 11)

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The sound pulses are transmitted at various frequencies
depending on the application. Very high frequencies (455kHz)
are used for greatest definition but the operating depth is
limited. High frequencies (200kHz) are commonly used on
consumer sonar and provide a good balance between depth
performance and resolution. Low frequencies (83kHz) 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.