Following are the errors that can be encountered in Echo Sounder:
1. Stylus speed error: The stylus is rotating with a certain constant speed and the speed of the stylus that the time is taken for the stylus to travel from top to bottom is exactly equal to that for an acoustic pulse to travel twice the distance of the range selected. Due to the fluctuation in the voltage, the speed of the stylus motor changes hence the depth recorded Will be inaccurate. It should be checked periodically and adjusted as per the instruction is given in the manual.
2. Multipath Echoes: The echo may be reflected a number of times between the keel and the seabed, thereby giving multiple depth marks on the record, in such case the first echo is the correct depth.
3. Pythagoras error: This error is found when two transducers are used one for transmission and other for reception.
4. Thermal and Density layer. The density of the water varies with temperature and salinity, which will tend to form different layers. It is possible for echoes to return from the surface of these layers and a faint line appears between zero and actual depth.
5. Zero line adjustment error If the zero adjustment is not correct, the depth recorded will not be correct.
6. The velocity of acoustic wave changes if temperature, salinity or pressure changes and since velocity is not correct, the depth recorded will be inaccurate.
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