The transmitter comprises an array of electro-acoustic transducers (1), each of which is connected to an oscillator circuit (9) which has a start input (11). The start inputs (11) successively receive start signals from a start signal generator (13) which comprises a number of comparators (15), each...http://www.google.fr/patents/US4457177?utm_source=gb-gplus-shareBrevet US4457177 - Ultrasonic transmitter
