Patent ID: 9341661
Filing Date: 2016-05-17
CPC Classification: G01R,H03K

Claim Text:
1. A tone detector comprising: a comparator configured to connect to an input, the input intermittently receiving a tone signal, such that the comparator generates a square wave output signal in response to the tone signal; one or more edge detectors configured to detect an edge of the square wave output signal and responsive to detection of an edge, generate a reset signal; a counter configured to generate a maximum value signal unless reset by receipt of the reset signal prior to reaching the maximum counter value; a logic element configured to receive the maximum value signal and an output from the one or more edge detectors and responsive thereto, generate a flip flop clocking signal; and a flip flop configured to receive the square wave signal and the flip flop clocking signal and in response output a first signal when a tone signal is not present at the input and a second signal when a tone signal is present at the input.