TDA7333

10/21

7.6 Group and block synchronization module

The group and block synchronization module has the following features :

– Hardware group and block synchronization

– Hardware error detection

– Hardware error correction using the quality bit information of the demodulator

– Hardware synchronization flywheel

– TAinformation extraction

– reset by software (ar_res)

Figure 9. Group and block synchronization block diagram

This module is used to acquire group and block synchronization of the received RDS data stream, which is pro-

vided in a modified shortened cyclic code. For the theory and implementation of the modified shortened cyclic

code, please refer to the specification of the radio data system (RDS) EN50067.

It further detects errors in the data stream. Depending on the quality bit information of the demodulator an error

correction is made.

The RDS data bytes are available to the software together with status bits giving an indication on the reliability

of the data.

It also extracts TA information which can be used as interrupt source (cf page 12).

S(4:0)

RDSCLK

RDSDAT

RDSQAL

rds_bd_h,rds_bd_l

rds_corrp

rds_qu

rds_int

RDSDAT(15:0)

Q(3:0)

CP(9:5)

Correct. pat.

Syndrome register

S(9:0)

Correction

logic

Corrected

Data_OK

Block

missed

QU(0:3)

RDS block counter

ABH

DBH

BLOCKE detected

Syndrom zero

Group & Block Synchronization Control Block

set

set

new

Block

available

next

RDS

bit

int

bit_int

res

AR_RES

read only

read only

read only

read/write

BLOCK A

Quality bit counter

from RDS

Demodulator

BLOCK B

BLOCK D

TAEON

TA