| 摘要 |
<p>The remote control or e.g. intruder alarm system, includes a transmitter which produces several carrier frequencies simultaneously from several partial transmitters (1,2,3). These signals are received by a corresponding group of partial receivers (10,11,12) which control operation of gates (22,24). The received signals are decoded into analogue form (14-16) and applied via resistors (19-21) to the control electrodes of transistors serving as the gates. When the transmitters simultaneously transmit, the respective gates may become conducting, and for example, an alarm signal (18) may be initiated. This is powered from a battery (17) via a switch (13). The system is less susceptible to interference than a single transmission. The transmitted signals may be radio waves, or ultrasonic or light signals. They may also be sequential, rather than simultaneous.</p> |
