SAA7284ZP データシートの表示（PDF） - Philips Electronics

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SAA7284ZP

Terrestrial digital sound decoder for conventional intercarrier PLL-IF systems

Philips Electronics 

Philips Semiconductors

Terrestrial digital sound decoder for

conventional intercarrier PLL-IF systems

Preliminary specification

SAA7284

Channel coding

Time-slots are encoded as biphase mark data. Each bit

transmitted is represented by a symbol comprising two

consecutive binary states. The first state of a symbol is

always different from the second state of the previous

symbol. The second state of the symbol is identical to the

first if the bit being transmitted is logic 0, however it is

different if the bit is logic 1 (see Table 14).

Table 15 Preambles

PRECEDING STATE

PREAMBLE

B

M

W

0

1

CHANNEL CODING

11101000

11100010

11100100

00010111

00011101

00011011

Table 14 Channel coding

PRECEDING STATE

TRANSMITTED BIT

0

1

0

1

CHANNEL CODING

11

00

10

01

Preambles

Preambles are specific patterns providing synchronization

and identification of the sub-frames and blocks.

A set of three preambles is used. These preambles are

transmitted in the time allocated to four time-slots and are

represented by eight successive states. The first state of

the preamble is always different from the second state of

the previous symbol. Depending on this state the

preambles are as shown in Table 15.

The preambles preceding each digital audio sample are

used to indicate the beginning of a sample as follows:

• Preamble B indicates the start of Channel A data and

the beginning of a block

• Preamble M indicates the start of Channel A data but

not the beginning of a block

• Preamble W indicates the start of Channel B data.

Channel status

The channel status information is organized in 192-bit

words. The first bit of each word is carried in the frame with

Preamble B. The 192-bit word is organized into sections

as shown in Table 16.

Table 16 Channel status codes

BIT

0

1

2

3 and 4

5

6 and 7

8 to 15

16 to 19

20 to 23

24 to 27

28 and 29

30 to 191

CODE

0

0

1

00

11

0

00

00110001

0000

0000

1100

00

all 0s

DESCRIPTION

consumer

sound data

digital copy permitted

indicates digital de-emphasis switched in

indicates digital de-emphasis switched out

−

−

category code

source code (don't care)

channel number (don't care)

sampling frequency (32 kHz)

clock accuracy (level II)

−

1996 Oct 24

19

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