| 摘要 |
<p>The invention relates to a device and a method for operating a smoke alarm having at least one light-transmitting unit (1) and at least one light-receiver unit (6), wherein the light receiver unit (6) receives light (5) which is emitted by the light transmitting unit (1) and is scattered/reflected in at least one light measuring section (R1, R2), wherein the light measuring section (R1, R2) is arranged at least partially outside a housing which accommodates the components of the smoke alarm and in which an intensity-modulated light (2) is emitted with the light-transmitting unit (1) in a measuring step starting from a transmission starting time (T0), wherein the frequency of the intensity modulation changes over time according to a predefined modulation function (8), and the light-receiver unit (6) is tuned to an intensity modulation frequency, which is to be received, of light (5) which is received from the light measuring section (R1, R2), in such a way that starting from an adjustable reception time (TE) the tuned reception frequency changes with the same modulation function (10), and a receiver output signal (11) is detected during the frequency tuning.</p> |
