A hydrophone which is automatically inhibited when the immersion depth exceeds a predetermined threshold by action, on the push element of a switch, of a flexible wall that bends under the action of the outside pressure. The first circuit processes a radio frequency ripple signal to obtain a first processed signal that is multiplied by a first gain value so as to result in a first signal. The bypass circuit includes a electrifying decision circuit that generates an activation signal for activating the control circuit in accordance with the load being put in an operation state. The network device receives TCP data packets and stores them in a queue.