Address free fault location in PCM system - uses closed loop digital test system evaluating bit failures over repeated cycles

摘要

The address free fault location system is for use with the transmission of digital, in particular PCM, signals over distances requiring intermediate repeating stations (ZWR1 to ZWRn). The transmission (OS) includes a closed loop digital signal (PF11 to PFin) and test signals that can be analysed by the receiver (OE). The intermediate stations can send signals both ways. The loop closed signal in a digital HDBn or mBnT code only becomes operative after a number of repeated cycles and evaluation for bit failures and signal delay time.