TDA7333 Datasheet, PDF (8/21 Pages) STMicroelectronics – RDS/RBDS PROCESSOR

TDA7333
Figure 7. Phase Response of the RDS Bandpass Filter
Phase of RDS Filter
3
2
1
0
1
2
3
5.6
5.65
5.7
Frequency [Hz]
5.75
5.8
x 10 ⁴
The output sample of the bandpass filter is picked up from a linear interpolator with sinc2 characteristics. The
interpolation factor is 32. A zero cross detection is simply formed by taking the sign bit of the interpolated signal.
This signal which contains only phase informations is processed by the RDS Demodulator.
7.5 Demodulator
– The demodulator includes :
– RDS quality indicator with selectable sensitivity
– Selectable time constant of 57kHz PLL
– Selectable time constant of bit PLL
– time constant selection done automatically or by software
Figure 8. Demodulator Block Diagram
MPX
Input-stage
(digital Filter)
ARI-indicator
57 kHz PLL
frequency
offset comp.
Sine comp.
Cosine comp.
mclk
(8,550 or 8,664 MHz)
to RDS group and block synchronisation
module:
RD
RDSDAT
RDSQUAL
from RDS group and block synchronisation
module:
AR_RES
Half Wave
Integrator
mclk
Clock Generator
1187.5Hz
PLL
Half Wave
Extractor
RDS Data
Extractor
RDS Quality
Extractor
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