Patent ID: 7357306
Filing Date: 2008-04-15
Classification: B65H,G07D,G07F

Abstract:
1. An apparatus comprising: a sound transmitter, operative to transmit a sound signal through a pathway; a sound receiver operative to produce at least one receiver signal responsive to the sound signal after having passed through the pathway; a first correlation filter and a second correlation filter, wherein the first correlation filter is operative responsive to the at least one receiver signal and a first reference signal to generate a first output representative of a difference in phase with respect to the at least one receiver signal and the first reference signal, wherein the second correlation filter is operative responsive to the at least one receiver signal and a second reference signal to generate a second output representative of a difference in phase with respect to the at least one receiver signal and the second reference signal, wherein the second reference signal lags in phase relative to the first reference signal; at least one processor, wherein the at least one processor is operative responsive to changes in the first and the second outputs of the correlation filters to determine information representative of a phase delay produced in the sound signal responsive to the sound signal passing through sheet media in the pathway, wherein the at least one processor is operative to distinguish between sheet media in the pathway that corresponds to a single sheet and sheet media in the pathway that corresponds to multiple sheets responsive to the information representative of phase delay.