Fishing and Gear Technology

Unit 16 - Electronic equipments for fishing

16.3.Echo Sounder
The echo sounder is the most common fish detection device. It consists of four main components, the transmitter, the transducer, the receiver and the recorder. The function of the transmitter is to produce energy in the form of pulses electrical oscillations. The transducer converts the electrical energy is to sound in the water and conversely the sound waves of the returning echoes to electrical energy. The function of the receiver is to amplify the weak electrical oscillations produced in the transducer by the echo, so that they can be recorded and displayed. In modern fish finding echo sounders various signal processing controls are built into the receiver. The echoes from nearest targets are stronger than those from distant targets. From the echo gram or display one can understand the relative abundance of fish at a particular depth. To read the depth of occurrence of the fish or sea bed directly from the echogram or display, the time delay is calibrated to a scale marked in meter or fathom or both.