Overview

The LC7851E demodulates the QPSK (quadrature phase shift keying) modulated audio data broadcast by the Japanese BS and CS broadcast satellites and converts that data to an analog audio signal. This IC integrates on a single chip the audio system signal processing required for BS and CS receivers from QPSK demodulation to analog audio reproduction. The main functions provided by the LC7851E include QPSK demodulation, differential decoding conversion, descrambling, deinterleaving, and error correction. It also generates a PCM audio signal. The PCM audio signal is converted to an analog audio signal by on-chip digital filters and A/D converters.

Features

• QPSK demodulator, PCM decoder, digital filters, D/A converters, and operational amplifiers integrated on a single chip.

• The number of required external components has been reduced and adjustment-free operation achieved in the QPSK demodulator by implementing that block as a digital circuit on a single chip.

• CPU interface using an I2C bus

• Interface circuits for CORTEC and SkyPort descramblers