PARITY MONITORING SYSTEM APPLIED TO DIGITAL TRANSMITTER PUT IN SCRAMBLING OPERATION

摘要

PURPOSE:To monitor accurately the quality of transmission by a parity check on a scrambled input signal by ORing exclusively the parity count result of the input signal and that of a scramble signal. CONSTITUTION:A scramble period is denoted as TS and a parity check period is represented as TP; and scramble periods are represented as TP1-TPN from the initial time slot in order, and this section is regarded as the parity check section. The parity count result of the input signal in a section TPi (i=1-N) is denoted as Pi and that of the scramble signal is represented as PSi, which is calculated previously and stored in a memory M. Counted values TPi are read out of the memory M successively through a read circuit R corresponding to the periods TPi while synchronizing with a timing signal C and EXORed with a counted value Pi to output the parity check bit R'i of the scrambled signal. Consequently, the quality of transmission is monitored accurately regardless of the length and contents of the scramble signal.