Binary registration mark detection using 3-state sensing and matched filtering

摘要

A system and method for detecting a registration mark representing a binary code sequence of N bits. A sensor is provided to output values indicating whether positive bits, negative bits, or no bits of the binary code sequence are detected. A sequence of N sensor values are provided to a code matching filter for comparison with the binary code sequence. The code matching filter increases a value of a detection signal for each sensor value which matches its corresponding bit, decreases the detection signal value for each sensor value which is complementary to its corresponding bit, and neither increases nor decreases the detection signal value in response to a sensor value indicating detection of no bit of the binary code sequence. When the binary code sequence is a Barker code, the code matching filter yields the ideal Barker auto-correlation function response whenever the binary code sequence is detected.