Abstract: The electromagnetic transmission in an interference-laden environment of events defined by the time of their occurrence is accomplished by repeatedly generating, at equal intervals after occurrence of the event, signals representing the occurrence of the event. An event which must be defined by the time t.sub.e at which it occurs triggers a switch which in turn triggers a time base whose signal is sent to a counter. The counter produces at its output a sequence of pulses which are coded in a coder. The code indicates for each pulse the deviation in time .DELTA.T.sub.i which separates it from the time at which the event occurred. The sequence of pulses is sent electromagnetically to a receiver via a transmitter. The first interference-free pulse received is processed by a decoder which provides the value .DELTA.T.sub.i to an arithmetic unit. The arithmetic unit subtracts the value .DELTA.T.sub.i from the time of day t.sub.h to obtain the time of day t.sub.e of the event.

Abstract: A plurality of contacts, each comprising two electrodes, are arranged beh a plate to be used as a touch pad in a swimming competition timing device. Closing of a contact results in a signal being transmitted from a transistor to control electronic chronometric equipment. The contacts are connected in parallel and are coupled between the emitter and base of the transistor. The voltage across the contact is thereby held to the base-emitter voltage of the transistor, which is below the decomposition voltage of the electrodes. In a second embodiment, contacts are connected to either of two transistors which are in series to act as an "OR" circuit.