Abstract: The invention is related to a method and a device for use in an apparatus, preferably a portable radiotelephone, equipped with a number of keys. Upon activation of a key, the device detects which key has been activated. The device comprises a signal generating unit which generates an oscillating signal whose character, e.g. frequency, unambiguously corresponds to the activated key. A signal detecting unit determines from the character of the oscillating signal a digital value which unambiguously indicates which key has been activated. An advantage offered by the invention is that the device can be implemented by use of simpler and cheaper circuits than prior known devices of similar type.

Abstract: A device for use in an apparatus, preferably a radiotelephone, is equipped with a plurality of keys. Upon activation of a key, the device detects which key has been activated. The device includes a signal generating unit which generates an oscillating signal whose character corresponds to the activated key. A signal detecting unit determines, from the character of the oscillating signal, a digital value which indicates which key has been activated.