Abstract
The Radio Data System (RDS) intends to improve functionality of FM receivers. Additional information - e. g. call sign, tuning frequency, alternative frequencies, time and date, traffic information, public or encrypted messages,... - can be transmitted during stereophonic or monophonic VHF/FM sound broadcasts. An ASIC is described which can receive or transmit RDS-data-patterns in a standalone or a microprocessor-based environment. Working as a transmitter or as a pattern-generator, the ASIC is able to encode and transmit RDS messages without any microprocessor support. A maximum sequence length of 64 kByte of data can be loaded from an external EPROM using on-chip direct memory access counters. Working as a receiver, the ASIC will detect block synchronisation, receive RDS data blocks and correct errors without any software overhead. A data block is checked and validated in less than five microseconds. An integrated FIR-filter detects valid block sequences immediately, even in the precence of random data which produces false synchronisation pulses on average five times per second. Last not least, due to its extended addressing capabilities, the ASIC can be used as a memory address expander when small single chip microprocessors with limited RAM will have to read and store RDS data during a longer perlod of time. Target technology is 0.8 μm CMOS, the ASIC utilizes the equivalent of 80 k MOS-Transistors.
Published Version
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