Importance

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Abstract

A dial pulse restorer for receiving and restoring telephone dial pulses which may be distorted, and also for discriminating telephone-hang-up pulses which may be applied to a telephone line when a remote telephone coupled to the telephone line hangs up. A particular use for such a dial pulse restorer is to control the functions of dictation apparatus operatively coupled to one end of the telephone line in response to the operation of the dial mechanism at the remote telephone. The dial pulse restorer comprises a transition pulse generator for generating transition pulses in response to telephone pulse transitions that are received over the telephone line, such telephone pulse transitions being received either in response to telephone dial pulses or to a telephone hang-up pulse. A window generator is responsive to a transition pulse to generate a window pulse of predetermined duration and substantially centered on the expected time of occurrence of the next following transition pulse. A control pulse generator produces a control pulse in the event that the next-following transition pulse occurs during the window pulse duration; and a hang-up pulse detector indicates the receipt of a telephone hang-up pulse if a transition pulse does not occur during the window pulse duration.

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First Claim