STV82X6D datasheet(47/95 Pages) STMICROELECTRONICS

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STV82x6

CAROFFSET1

Channel 1 DCO Carrier Offset Compensation

9.7

Demodulator Channel 2

IAGCR

Channel 2 Internal AGC Reference for QPSK

Bit Name

Reset

Function

SQTH1[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 (hex): 22h

Type: R/W

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

CAROFFSET1[7:0] (S)

Bit Name

Reset

Function

CAROFFSET1[7:0]

00000000

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

frequency control in FM mode can be implemented by registers FM_DCR and FM_DCL.

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

by AUTOTSD in the CARFQ1 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 displays by FM_DCL can be directly loaded in

CAROFFSET1 to exactly compensate the carrier offset on Channel 1

Address (hex): 25h

Type: R/W

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

IAGC_REF[7:0]

Bit Name

Reset

Function

IAGC_REF[7:0]

10001000

Sets the mean value of the internal AGC, used for QPSK demodulation. The default setting

corresponds to half full scale amplitude at the baseband PLL input.

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