| 摘要 |
TDM DATA TRANSMISSION SYSTEM The invention concerns a system for transmitting digital data by TDM, the system comprising a transmission terminal for transmitting a TDM data stream having a frame structure which includes fixed stuff bytes and/or frame overheads forming part of the payload but not normally available to the user. The system includes processor means for locating said fixed stuff bytes, and overwriting at least some of the said fixed stuff bytes to introduce mark parity, and a receive terminal having processor means for detecting the introduced parity bytes and determining whether or not there has been an error in transmission. The processing means at the receive terminal comprise an AND-gate 20 to which the transmitted TDM signal containing mark parity is fed, means for supplying a clock signal to said AND-date, a bistable 21 connected to the output of said AND-gate, and a band pass filter 22 for filtering the output of said AND-gate. |
