| IFREMER is involved in long range oceanography experiments, such as acoustic tomography, using very low frequency transducers. Thus, the possibility to measure in tank or in pool the transducer Transmitting Voltage Response (TVR) is a real need for reliability controls after several months deployment at sea. Because of large wavelengths, usual methods like burst excitation are unsuitable to tank measurement. The use of Maximum Length Sequences (MLS) allows the fast determination of the impulse response of the system made up the projector and its environment. MLS generation and signal cross correlation calculation using Fast Hadamard Transform are achieved by a software called "MITAS". The separation between transducer contribution and environment effect... |
