RDS DEMODULATOR IC
S1A0905
1
Preliminary
GENERAL DESCRIPTION
THE OUTLINE OF RDS(RADIO DATA SYSTEM)
Since 1988 most European national broadcaststations transmit RDS-
code beside their audio signals. RDS means Radio Data System and
was originally intended to give people in their cars additional informa-
tion about the weather or traffic(jams). But RDS has grown out to one
big channel of information. Radiostations send their name, the time
(with DCF-77 accuracy), their type of music (format) and even more.
The digital data of RDS are multiplexed into an FM radio wave using a
sub-carrier of 57kHz. The transmission rate of RDS data is
1.1875kbit/sec.
The transmission rate of RDS data is 1.1875kbit/sec, and RDS data
are encoded by differential encoding method. Then the encoded RDS data are modulated by BPSK using a clock
of 1.1875kHz. The modulated RDS data is are modulated by carrier suppressed amplitude modulation using a sub-
carrier of 57kHz. And that signal are multiplexed into an FM radio wave.
•RDS data are obtained by demodulating the received RDS modulation signal in RDS demodulator. First, the RDS
modulation signal is extracted from an FM radio wave using a band pass filter. The BPSK signal is obtained from
extracted RDS modulation signal by a 57kHz carrier recovery circuit. Then the bit rate clock of RDS data is
extracted from the BPSK signal, and the BPSK signal is demodulated using the extracted clock signal. Then the
RDS data are decoded by a differential decoding method using the demodulated BPSK signal.
FEATURES
•
Low Current
•
Two Stage Anti-aliasing Filter
•
8'th 57kHz Switched Capacitor Bandpass Filter
•
DSB Demodulation (Carrier Recovery)
•
Clock Recovery Circuit
•
Biphase Decoder & Differential Decoder
•
Quality Indication Output for Demodulated Data
ORDERING INFORMATION
DEVICE
PACKAGE
OPERATING TEMP.
S1A0905-S0B0
16-SOP-225
-40
−
+85
16
−
SOP
−
225
