TDA8960 datasheet(13/32 Pages) PHILIPS

13 / 32 page

1999 Jun 14

Philips Semiconductors

Preliminary speciﬁcation

ATSC 8-VSB demodulator and decoder

TDA8960

Transport stream interface

The transport stream interface provides an output of 8-bit

parallel MPEG-2 transport packets at a data rate of

5.38 Mbytes/s.

IMPLEMENTATION

The transport interface consists of a FIFO, which has two

tasks:

1. Removal of the field sync segment from the generation

of output data

2. Increase of the data rate of the de-randomizer from

2.69 to 5.38 MHz.

Basically the 208 bytes of a field segment (187 data bytes,

20 error correcting bytes and one segment sync byte) are

distributed over the remaining 312 data segments.

The FIFO has a depth of two data segments. As the output

data rate is 5.38 MHz we have to distribute 416 bytes, or

two field sync data segments over 312 data segments.

Every MPEG-2 transport packet corresponding to a data

segment gets a delay equal to one 5.38 MHz clock cycle.

Further, every third MPEG-2 transport packet gets an

extra delay of one 5.38 MHz transport packet.

EXTERNAL INTERFACE

The transport stream consists of four signals and one data

bus as shown in Table 4.

Table 4

Transport stream interface

FUNCTIONAL DESCRIPTION

The timing of the transport stream interface signals is shown in Fig.5.

NAME

FUNCTION

DATACLK

output clock

DATAVALID

valid demodulator output data or one valid MPEG transport packet

DATA[7 to 0]

output data stream (8-bit wide output bus)

SOP

indicates the start of a packet. It goes HIGH at the start of a packet and remains HIGH

during the ﬁrst byte of the packet, the so called sync byte

ERROR

a transport packet error indicator, which is HIGH for each 188 byte transport packet in

which the Reed Solomon decoder found more errors than it could correct

Fig.5 Timing diagram of the transport interface (normal mode).

handbook, full pagewidth

MGR604

MPEG-2

sync byte

DATACLK

DATAVALID

DATA7 to DATA0

SOP

ERROR

185.9 ns

188 bytes/34.9

µs

188 bytes/34.9

µs

77.5

µs

00H

sync

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