Method and apparatus for detecting transitions in a time sampled input signal

摘要: A method and apparatus for determining the transitions between binary levels of an input signal such as a scanned bar code label by detecting zero crossings approximated second derivative signal. Samples are obtained using delay lines, sample-and-hold circuits, analog shift register or similar device. The first is slope straight line two sampled points on waveform. difference derivatives. Zero indicating may be determined either peak both sides crossing, comparing to when exceeds positive negative threshold. time sample adjusted match particular range setting scanner having plurality settings.