Patent ID: 6574334
Filing Date: 2003-06-03
Classification: H04M

Abstract:
A method for determining energy threshold detection values for detecting at least one tone having a known frequency and duration in an input signal, the input signal being input over a period of time, the period of time being divided into frame portions including at least an initial frame portion and a last frame portion, an energy value being determined for the at least one tone during each frame portion, the method comprising:generating data signals thereby defining a data table including scaling coefficients and addresses of the energy values for at least two frame portions; setting control flag signals defining a control word for the at least two frame portions, the control flag signals being set based on the energy values being below a threshold value in previous frame portions, and the presence of noise in previous frame portions; determining an offset into the data table based on the control word; and retrieving a scaling coefficient and an address of an energy value from the data table based on the offset.