Selecting a geographical area for accurate target tracking

When you have an echo you wish to track, the tracking functionality places a geographical area around the object. An invisible area - the tracking area - is created as an acquisition area. In order for the ST90 system to find and lock on the intended target, it needs to be kept within this tracking area. If the intended target falls outside the area, the tracking can not be started.

Illustration:

  1. Each Tracking Area option controls the distance from the inner to the outer radius of the area.
  2. The width of the area is fixed, and stretches across a predefined number of beams. This means that the actual width depends on the distance from your vessel to the area.

The Tracking Area function is used to select the physical size of the area. You can choose from a set of predefined sizes.

To track a target efficiently, the area should be as small as possible. For example, use a small area if you track single fish or small schools. However, if the target is large, or moves very fast, a larger area may be beneficial. This may be useful if you track a large school of fish.

Tip:

Under certain circumstances the target tracking may not follow the intended echo. This may for example happen if the tracking area is too large.

Procedure

  1. Open the Setup menu.
  2. Use the Tracking Area function to define the size of the area that you want to detect moving objects in.

Use the Tracking Area Setup dialog box to change the size of the predefined area sizes.