Measuring Procedure Function Sequence
- The sonar system is based on the ultrasonic measuring procedure. As such, the sonar control unit actuate the sonar sensors directly.
- As a result of this these emit an ultrasonic signal. The ultrasonic waves reflected by an obstacle are received again by the sonar sensors. The sonar control unit directly reads in the signals of the sonar sensors and evaluates them. In principle a distinction is made between two measurements. On the one hand the direct measurement, resulting from a direct echo and on the other hand the indirect distance measurement which is achieved via a cross echo. Echoes can usually also be received from adjacent sonar sensors due to the large sonar sensor detection angles; these are known as cross echoes. These occur at the obstacle due to scattered reflection. The distance between the vehicle and obstacle can be calculated from two echo signals using the triangulation method. The propagation times of the signals from the direct measurement and from the cross measurement are required for this method. A long signal runtime thus equals a long distance between the vehicle and the obstacle, a short signal runtime equals a short distance between the vehicle and the obstacle.
NOTE:
The sonar system cannot work correctly in certain cases due to the function principle (transmitting and receiving sound waves). So for example, when approaching a strong sound absorbent obstacle (e.g. a vehicle covered in snow) it is possible that false data may be displayed.