| 摘要 |
In a two-way remote control system a plurality of apparatus, including the hand-held unit, does not only comprise a transmitter but also a receiver. The receiver, inter alia, in the hand held unit is battery-fed. Since the receiver must be continuously in the operative state, this battery is exhausted very rapidly. To improve this, transmitters which deliver messages of a particular type have been selected in this system. In fact, each message comprises a series of pulses and the beginning of each message is marked by a wake-up pulse. At least the receiver which is battery-fed is provided with a wake-up pulse detection circuit controlling a switching circuit which switches the receiver from a rest state to the operative state after it has received of a wake-up pulse and which switches the receiver back to the rest state, in which state it consumes very little energy, if no wake-up pulse has been received for a certain period. |
