| 摘要 |
Signal recognition circuitry provides a control signal which is initiated following the receipt of successive input signals provided they are spaced less than a first duration apart and have been received for at least a second duration with such control signal continuing for at least a third duration. A first pulse generator is controlled by the input signals and is used to assure that the spacing between pulses is proper by producing a pulse if the spacing is improper with such pulse being used to inhibit operation of a second pulse generator used to measure the second duration. The second pulse generator controls operation of a switching circuit and operation of a third pulse generator. If the second duration is satisfied, a pulse is provided by the second pulse generator causing the switching circuit to provide the control signal. The third pulse generator begins operation after the pulse has been provided by the second pulse generator and connects with the switching circuit to terminate the control signal in response to a pulse produced by the third pulse generator when it has been operating for said third duration. |
