MT312 Zarlink Semiconductor, MT312 Datasheet - Page 15

• Manufacturer Part Number: MT312
• Description: Satellite Channel Decoder
• Manufacturer: Zarlink Semiconductor

2.4.4
DVB and DSS data are encoded using shortened versions of the Reed-Solomon code of block length 255,
containing 239 message bytes and 16 check bytes, that is (255,239) with T = 8. Both encoders use the same
generator polynomial. The code block size for DVB is 204 and that for DSS is 146. Hence DVB code is (204, 188)
and DSS code is (146, 130), with both having T = 8. The block structure of the DVB and DSS Reed-Solomon codes
are as shown in Figure 8 and Figure 9 below.
The Reed-Solomon decoder can correct up to eight byte errors per packet. If there are more than eight bytes
containing errors, the packet is flagged as uncorrectable using the pin BKERR. In the case of DVB the Transport
Error Indicator (TEI) bit of the MPEG packet is set to 1, if setting of TEI is enabled.
The Reed-Solomon decoder block
One
byte per
position
Figure 6 - DVB conceptual diagram of the convolutional de-interleaver block
Figure 7 - DSS conceptual diagram of the convolutional de-interleaver block
Input
10
11
0
1
2
3
4
5
6
7
8
9
12D
Zarlink Semiconductor Inc.
Sync word route
17x11 bytes
MT312
17x10 bytes
15
17x9 bytes
17x8 bytes
17x7 bytes
12D
17x6 bytes
17x5 bytes
17x4 bytes
17x3 bytes
2
17x2 bytes
145
1
0
17x1
12D
Output
10
11
0
1
2
3
4
5
6
7
8
9
Design Manual