Patent ID: 6073849
Filing Date: 2000-06-13
Classification: G06K

Abstract:
In a barcode scanner system, a second derivative signal processor for detecting edges representing bar and space transitions in an input signal, said second derivative signal processor comprising an overall filter polynomial having even order which further comprises:a first filter receiving the input signal and providing a filtered signal;a first output channel terminating with a first filter having a complex pole pair with a first cutoff frequency and damping ratio, said first output channel receiving the filtered signal and producing the first derivative of the input signal; and,a second output channel parallel to said first output channel and terminating with a second filter having a complex pole pair with the first cutoff frequency and damping ratio; said second output channel receiving the filtered signal and producing the second derivative of the input signal,wherein the first filter is a low pass filter of second order and the second filter is a high pass filter of second order, and wherein the cutoff frequency and damping ratio of the low pass filter and the high pass filter are substantially equal.