Effect of Range Resolution on the performance of Monotonic and Chirp Technology Sonar

Abstract

Avoiding collision of the Autonomous underwater vehicle (AUV) with the floating or fixed objects in the underwater scenario needs either apriori knowledge of the operating environment or sensing equipment for evaluating the environment in real time. The sensing equipment in this case is the forward looking Sonar that is mounted on the AUV which scans the area in front and provides the images as the output. The technology used in this forward looking SONAR is CHIRP. In SONAR, Surface Acoustic Wave devices such as Reflective array Compressors are used to generate the chirped signals. Because of Chirp technology high resolution images of sea bed are produced. The range resolution of the CHIRP technology SONAR is much better than conventional monotonic SONAR. With monotonic SONAR it is very difficult to differentiate two objects separated by less than 37.5 mm whereas using CHIRP technology SONAR it is easy to distinguish the objects if they 7.5mm apart. In this paper the generation of Chirp pulse is analyzed. The pulse compression technique and different windowing techniques are analyzed to detect the peak of the received signal.