| 摘要 |
PURPOSE:To simplify the circuit constitution of a code error detecting circuit for HDBn codes, by monitoring digital integral values of the HDBn codes by using a universal shift register. CONSTITUTION:The principal part of an error detecting circuit which detects errors of HDBn (High Density Bipolar n) codes used by a digital transmission system consists of two stages of universal shift registers and two AND gates 22 and 24. The universal shift registers 20 are capable of transferring data to left and right and this operation is utilized to monitor digital integral values of HDBn codes. An HDBn code free from a code error never has >=3 successive pulses of the same polarity, so the largest digital integral value of the HDBn is 2 and when the digital integral value exceeds two, the code is regarded as an error. |
