DRAHTLOSER MELDER UND ALARMMELDER

摘要

A radio or alternatively ultrasonically operated alarm network consists of a small button operated transmitter. It is carried typically by an old or sick person. There is a remote receiver and associated acoustic or optical alarm, which is intended for personal protection of the person carrying the transmitter and which can also be used in certain burglar alarm situations, such a window protection. The transmitter consists typically of a quartz crystal frequency defined UHF radio transmitter which transmits a multivibrator modulated signal from an amplified transmitter and aerial when power is applied to the circuit by an alarm button. At some remote point, a receiving aerial and receiver amplifier set, process the signal and activate an acoustic or optical alarm device via relays.