| 摘要 |
<p>The electrical load control system 10 of the invention is illustrated with reference to a controller 10 intended to control an electrical load constituted by a hot water cylinder 12. The controller 10 relies on a public broadcaster to inject switch actuation codes into the normal signal broadcast by the broadcast, either as radio frequency (RF) signals, preferably in the form of RDS (Radio Data System) signals, or as audio frequency, in-band signals, whether in the form of humanly audible tones or as inaudible tones having an audio frequency outside of the normal humanly audible frequency range. The system or controller 10 comprises, at the load 12, a switch 14 connected in circuit with the electrical load 12. The controller 10 includes a RF receiver 20 preset to receive the RF signal of a predetermined public broadcasting service. In the audio-signal embodiment of the invention, the receiver 20 receives the broadcast RF signal and outputs an audio signal through an audio output transducer (not shown) similar to an audio speaker. The controller 10 includes an interface including a control circuit 22 that is interfaced with the switch 14 over a switch interface 24 and with the receiver 20 over a receiver interface 26. The control circuit receiver interface 26 is adapted to monitor the audio output of the receiver transducer for receipt of the publicly broadcast audio control signal. The control circuit 22 includes programmable logic means programmed, on receipt of the publicly broadcast audio control signal, to actuate the control circuit 22 by means of the switch interface 24, to actuate the switch 14, in use to switch the load OFF or ON.</p> |
