3
How Sonar Works
When all the echoes are viewed side by side, an
easy to interpret “graph“ of the bottom, fish, and
structure appears.
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.
