| 摘要 |
THE INVENTION IS RELATED TO A METHOD AND A DEVICE (500) FOR USE IN AN APPARATUS, PREFERABLY A PORTABLE RADIOTELEPHONE, EQUIPPED WITH A NUMBER OF KEYS (103). UPON ACTIVATION OF A KEY (103) , THE DEVICE (500) DETECTS WHICH KEY HAS BEEN ACTIVATED. THE DEVICE COMPRISES A SIGNAL GENERATING UNIT (523) WHICH GENERATES AN OSCILLATING SIGNAL WHOSE CHARACTER, E.G. FREQUENCY, UNAMBIGUOUSLY CORRESPONDS TO THE ACTIVATED KEY. A SIGNAL DETECTING UNIT (522) DETERMINES FROM THE CHARACTER OF THE OSCILLATING SIGNAL(702, 703) A DIGITAL VALUE (521) WHICH UNAMBIGUOUSLY INDICATES WHICH KEY HAS BEEN ACTIVATED. AN ADVANTAGE OFFERED BY THE INVENTION IS THAT THE DEVICE (500) CAN BE IMPLEMENTED BY USE OF SIMPLER AND CHEAPER CIRCUITS THAN PRIOR KNOW DEVICES OF SIMILAR TYPE.(FIG. 5)
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