User Manual DDS200 Digital Demodulation System 070-9952-00
User Manual DDS200 Digital Demodulation System 070-9952-00
User Manual DDS200 Digital Demodulation System 070-9952-00
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<strong>Manual</strong> OperationTransmission of 188data bytesTransmission of 16 errorprotection bytes203 SY 1 2 3 4 5181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 2<strong>00</strong> 201 202 203 SY 1 2 3 4180 DATA (0 to 7)CLOCKPSYNCSY: Sync byteDATA VALIDFigure 2–64: Signals at parallel interface in 188-byte mode (STATUS: SER/PAR MPEG FRAME SIZE)Transmission of 188data bytesTransmission of 16 errorprotection bytes203 SY 1 2 3 4 5180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 2<strong>00</strong> 201 202 203 SY 1 2 3 4DATA (0 to 7)CLOCKPSYNCSY: Sync byteDATA VALIDFigure 2–65: Signals at parallel interface in 204-byte mode (STATUS: SER/PAR MPEG FRAME SIZE)The serial MPEG-2 interface (X7) uses asynchronous data transmission(asynchronous serial interface, ASI). Asynchronous means that the datatransmission rate is fixed, irrespective of the data rate of the transmitted MPEG-2signal. To this end, padding bits are inserted where no valid information ispresent. With the serial MPEG-2 interface, very long transmission links (severalhundred meters) can be realized. The switch SER/PAR MPEG FRAME SIZE:188/204 bytes has the same function for the parallel and the serial interface: inthe 204-byte mode, the error protection bits are transmitted, in the 188-bytesmode, padding bits are transmitted instead of the error protection bits.<strong>DDS2<strong>00</strong></strong> <strong>Digital</strong> <strong>Demodulation</strong> <strong>System</strong> <strong>User</strong> <strong>Manual</strong> 2–87
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