SUPPORT > SIDE SCAN IMAGERY > ESTIMATING THE SONAR DEPTH

We have previously seen how we can calculate the depth below the sonar (altitude), and we can use a similar technique to estimate the sonar depth below the surface.

In the example image shown opposite, we can see two bright echoes close-up on either side of the sonar.

The echoes are produced by the transmitted sound from the sonar hitting and being reflected back from the surface of the water (as air is an excellent reflector of sound in water).

As the sound does not leave the sonar at 90° straight up, we cannot use this as a true depth.

However, this method gives a good rough estimate for general use.