STV8237 datasheet(71/149 Pages) STMICROELECTRONICS

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STV82x7

SQTH2

Channel 2 FM Squelch Threshold

CAROFFSET2

Channel 2 DCO Carrier Offset Compensation

12.7

NICAM Registers

NICAM_CTRL

NICAM Decoder Control Register

Address: 39h

Type: R/W

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

SQTH2[7:0]

Bit Name

Reset

Function

SQTH2[7:0]

00111100

The squelch detector measures the level of high frequency noise (> 40 kHz) and compares it to

the threshold level (SQTH). If the level is below this value, the S/N of the FM signal is

considered to be acceptable. Values are given for FM with standard deviation.

SQTH

S/N (dB)

FAh

77h

3Ch

15 (Default)

23h

19h

Address: 3Ah

Type: R/W

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

CAROFFSET2[7:0] (S)

Bit Name

Reset

Function

CAROFFSET2[7:0] 00000000

This value is used to correct the carrier frequency offset of the incoming IF signal. Automatic

frequency control in FM mode can be implemented by registers DC_REMOVAL_L and

DC_REMOVAL_R.

A DCO frequency offset (in two’s complement format) is added to the pre-programming value

by AUTOTSD in the CARFQ2 registers (corresponding to the standard IF carrier frequency).

The programmable carrier offset ranges from -192 kHz to +190.5 kHz with a resolution of

1.5 kHz.

For standard FM deviation, the value displayed by register DC_REMOVAL_R can be directly

loaded in register CAROFFSET2 to exactly compensate the carrier offset on Channel 2.

Address: 3Dh

Type: R/W

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

000

DIF_POL

ECT

MAE

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