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Am79C02/03/031(A) Data Sheet

A-Law and

µ-Law Companding

Table 1 and Table 2 show the companding definitions used for A-law and

µ-law PCM encoding.

Table 1. A-Law: Positive Input Values

Notes:

1. 4096 normalized value units correspond to TMAX = 3.14 dBm0.

2. The character signals are obtained by inverting the even bits of the signals of column 6. Before this inversion, the character

signal corresponding to positive input values between two successive decision values numbered n and n+1 (see column 4)

is 128+n, expressed as a binary number.

3. The value at the decoder output is

, for n = 1,...127, 128.

5. Bit 1 is a 0 for negative input values.

12

3

4

5

6

7

8

Segment

# Intervals

x Interval

Size

Value at

Segment

End Points

Decision

Value

Number n

Decision

(See Note 1)

Character

Signal pre

Inversion of

Even Bits

Quantized

Value (at

Decoder

Decoder

Output

Value No.

Bit No.

Number

1 2 3 4 5 6 7 8

4096

(128)

(4096)

7

6

5

4

1 1 1 1 1 1 1 1

4032

128

3968

127

2048

1024

113

112

97

96

See Note 2

1 1 1 1 0 0 0 0

2176

2048

2112

113

See Note 2

1 1 1 0 0 0 0 0

1088

1024

1056

97

512

81

80

See Note 2

1 1 0 1 0 0 0 0

544

512

528

81

256

65

64

See Note 2

1 1 0 0 0 0 0 0

272

256

264

65

3

128

49

48

See Note 2

1 0 1 1 0 0 0 0

136

128

132

49

2

64

33

32

See Note 2

1 0 1 0 0 0 0 0

68

64

66

33

1

1

0

See Note 2

1 0 0 0 0 0 0 0

2

0

11

16 x 128

16 x 64

16 x 32

16 x 16

16 x 8

16 x 4

32 x 2

y

n

x

n1

–

x

n

+

2

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