S1A0905

Preliminary RDS DEMODULATOR IC S1A0905 GENERAL DESCRIPTION THE OUTLINE OF RDS(RADIO DATA SYSTEM) 16−SOP−225 Since 1988 most European national broadcaststations transmit RDScode beside their audio signals. RDS means Radio Data System and was originally intended to give people in their cars additional information 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 subcarrier 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 deco...