| 摘要 |
<p>The signal absence detector controls an operator circuit which periodically provides an operator signal to render the processor circuit (12) in a communication receiver (10) operative. The absence detector responds to a processed signal which is not of a predetermined character to terminate the operator signal. In one form of the invention, the operator circuit is a battery saver (20) which intermittently provides a supply voltage. When the incoming signal is of the predetermined character, the supply voltage continues. The absence detector terminates the supply voltage when it is determined that the incoming signal does not have that character. In another form of the invention, the absence detector is employed in a scanning receiver, in which case the operator circuit steps the receiver between the various channels. The receiver will remain tuned to a channel as long as the incoming signal may be of the predetermined character. As soon as determination is made that the incoming signal does not have such character, the receiver is stepped to the next channel.</p> |
