Transmitter-receiver and method for transmitting and receiving digital information

摘要

For digital communication between a preferably stationary transmitter and a receiver temporarily located in the reception area of the transmitter, the radio-frequency signal containing the digital information is provided with an audio-frequency signal component serving as an activation signal. In the receiver, only one corresponding recognition circuit (13) for the activation signal then needs to be supplied continuously with power, whereas power is supplied to the other circuit components of the receiver only following reception and recognition of the activation signal by the recognition circuit (13). A recognition circuit (13) with a minimum power consumption, which nevertheless guarantees an adequately short response time for the receiver, is possible if the activation signal has a frequency of several kHz.