Errors of dopller log are as follow : –
Error in transducer orientation-
The transducers should make a perfect angle of 60° with respect to the keel or else the speed indicated will be inaccurate.
Error in Oscillator frequency-
The frequency generated by the oscillator must be accurate and constant, any deviation in the frequency will result in the speed indicated being in error.
Error in propagation velocity of acoustic wave-
The velocity of the acoustic wave at the temp of 16°C and salinity of 3.4% is 1505 m/sec, but generally it is taken as 1500 m/sec for calculation.
This velocity changes with temperature, salinity or pressure. To compensate the error due to temperature variation, a thermistor i.e. a resistance whose value changes with temperature, is mounted near the transducer and change in velocity of the acoustic wave through water from the standard value due to the change in sea water temperature is accounted for.
Leave a Comment