Method and device for locating at least one touch on a touch-sensitive surface of an object

A device for locating at least one touch on a touch-sensitive surface of an object, comprising:

• at least one transducer designed to transmit and receive elastic mechanical waves propagated in the touch-sensitive surface of the object;
• and
• one central processing unit, connected to said at least one transducer, configured:
• to propagate elastic mechanical waves in the touch-sensitive surface of the object from said at least one transducer and to detect said elastic mechanical waves by said at least one transducer in order to obtain at least one sensed signal, and
• to locate at least one touch on the touch-sensitive surface of the object by comparing certain spectral characteristics of the sensed signal to a set of reference characteristics, the set of reference characteristics including interfered radiation information for predetermined single or multiple touches received during a transient phase of the propagation of the transmitted waves when resonances have not been established in the touch-sensitive surface and the transmitted waves are not stable over time,
• wherein the central processing unit is further configured to start to measure the sensed signal during a time interval starting during the transient phase of the propagation of the transmitted waves, for supplying, to said at least one reception point, information on radiation interfered with by said at least one touch, such that the central processing unit is configured to locate of the at least one touch on the touch-sensitive surface includes based on a comparison of certain spectral characteristics of the sensed signal measured during the transient phase to the interfered radiation information included in the set of reference characteristics.