SAA6588 데이터 시트보기 (PDF) - Philips Electronics

부품명

상세내역

제조사

SAA6588

RDS/RBDS pre-processor

Philips Electronics 

Philips Semiconductors

RDS/RBDS pre-processor

Product specification

SAA6588

FUNCTIONAL DESCRIPTION

General

The following functions are performed by the SAA6588:

• Selection of the RDS/RBDS signal from the MPX input

signal

• 57 kHz carrier regeneration

• Demodulation of the RDS/RBDS signal

• Symbol decoding

• RDS/RBDS block detection

• Error detection and correction of transmission errors

• Fast block synchronization and synchronization control

• Detection of multi-path distortion and audio signal

pauses

• Determination of the signal quality

• Mode control of processing and RDS/RBDS data output

via I2C-bus interface

• Sensing of pause and multi-path, information via extra

output pins.

The block diagram of the RDS/RBDS pre-processor is

shown in Fig.1. For the application of the device only a few

external components are required. The pre-processors

functional blocks are described in the following sections.

RDS/RBDS signal demodulation

BAND-PASS FILTER

The band-pass filter has a centre frequency of 57 kHz.

It selects the RDS/RBDS sub-band from the multiplex

signal MPX and suppresses the audio signal components.

The filter block contains an analog anti-aliasing filter at the

input followed by an 8th order switched capacitor

band-pass filter and a reconstruction filter at the output.

CLOCKED COMPARATOR

The comparator digitizes the output signal from the 57 kHz

band-pass filter for further processing by the digital

RDS/RBDS demodulator. To attain high sensitivity and to

avoid phase distortion, the comparator input stage

contains an automatic offset compensation.

DEMODULATION

The demodulator provides all functions of the SAA6579

but has improved performance under weak signal

conditions.

The demodulator includes:

• 57 kHz carrier regeneration from the two sidebands

(Costas loop)

• Symbol integration over one RDS clock period

• Bi-phase symbol decoding

• Differential decoding

• Synchronization of RDS/RBDS output data with clock.

The RDS/RBDS demodulator recovers and regenerates

the continuously transmitted RDS/RBDS data stream out

of the multiplex signal (MPX) and provides the internal

signals clock (RDCL) and data (RDDA) for further

processing by the RDS/RBDS decoder block.

RDS/RBDS data processing

The RDS/RBDS data processing of the pre-processor

handles the complete processing and decoding of the

continuous serial RDS/RBDS demodulator output data

stream.

Different data processing modes are software controllable

by the external main controller via I2C-bus.

Processed RDS/RBDS data blocks, decoder status

information and signal quality information are also

available via I2C-bus.

RDS/RBDS DECODER

The RDS/RBDS decoder contains:

• RDS/RBDS block detection

• Error detection and correction

• Synchronization

• Flywheel for synchronization hold

• Bit slip correction

• Data processing control

• RDS/RBDS data output.

1997 Sep 01

6

Share Link: