VP310

PRELIMINARY DATA

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1.4.4 The Reed Solomon Decoder block

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 7 and

Figure 8 on page 10.

The Reed-Solomon decoder can correct up to eight byte errors per packet. If there are more than

8 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.

Sync byte

187 bytes

Sync byte

187 bytes

16 check bytes

Reed Solomon encoded block

MPEG transport packet

Figure 7. DVB block structure.

130 bytes

130 bytes

16 check bytes

Reed Solomon encoded block

DSS transport packet

Figure 8. DSS block structure.