Abstract: A main pulse train at a main frequency and at least two derived pulse tra at submultiples of the main frequency are transmitted over a transmission path, from a transmitter to a receiver, in the form of pulses of alternating polarity. A first one of the derived pulse trains is transmitted as a single violation of bipolarity in the main pulse train while a second one of the derived pulse trains is transmitted as two successive violations of bipolarity in the main pulse train. The system is applicable to multiple synchronization (bit, frame etc . . . ) in a PCM digital transmission or switching system.

Abstract: The invention concerns a position measuring device used for measuring the sition of a vessel equipped with three hydrophones arranged at the apexes of a right-angled triangle in relation to a transmitting beacon on the sea bed. Measuring of the differences in the travel time between the beacon and the various hydrophones as well as of the depth of the water and analogic calculating of the position of the vessel in a simple way and without approximation.