21/25

¡ Semiconductor

MSM7575

(4) CR3 (Side tone and other tone generator gain setting)

The tone generator gain setting table for receive side, shown by Table-4, depends upon the

following reference level.

DTMF low-group tones ................................ –2 dBm0

DTMF high-group tones and others ............ 0 dBm0

For example, when selecting –6 dB (B3, B2, B1, B0) = (1, 1, 1, 1) as a tone generator gain, each DTMF

tone signal amplitude on SAO or VFRO is as follows.

DTMF low-group tone .................................. –8 dBm0

DTMF high-group tone or other tones ....... –6 dBm0

B7, B6, B5 ... Side tone path gain setting, refer to Table-3.

B4 ... Tone generator enable :

0/Disable, 1/Enable

B3, B2, B1, B0 ... Tone generator gain adjustment for receive side, refer to Table-4

Table-3 Side Tone Gain Setting Table

B7

B6

B5

00

0

00

1

01

0

01

1

10

0

10

1

11

0

11

1

Side Tone Path Gain

OFF

–21 dB

–19 dB

–17 dB

–15 dB

–13 dB

–11 dB

–9 dB

Table-4 Receive Tone Generator Gain Setting Table

Side. Tone

Initial Value

CR3

Side. Tone Side. Tone

TONE

TONE

TONE

TONE

TONE

GAIN0

0

0000000

B7

B6

B5

B4

B3

B2

B1

B0

GAIN2

GAIN1

GAIN0

ON/OFF

GAIN3

GAIN2

GAIN1

B3

B2

B1

B0

00

0

0

00

0

1

00

1

0

00

1

1

01

0

0

01

0

1

01

1

0

01

1

1

Tone Generator Gain

–36 dB

–34 dB

–32 dB

–30 dB

–28 dB

–26 dB

–24 dB

–22 dB

B3

B2

B1

B0

10

0

0

10

0

1

10

1

0

10

1

1

11

0

0

11

0

1

11

1

0

11

1

1

Tone Generator Gain

–20 dB

–18 dB

–16 dB

–14 dB

–12 dB

–10 dB

–8 dB

–6 dB