The AD71028 dual digital BTSC encoder provides two complete digital BTSC encoder channels, including the pilot-tone generation and subcarrier mixing functions. Two built-in high performance DACs are provided to output the BTSC baseband composite signal. The output of the AD71028 can be connected with minimal external circuitry to the input of a 4.5 MHz aural FM modulator.
In addition to the BTSC encoders, the AD71028 also includes a stereo image enhancement function, Phat Stereo, to increase the sense of spaciousness available from closely spaced TV loudspeakers. A dialog enhancement algorithm is also included to solve the problem of playing wide dynamic range sources over limited-performance TV speakers and amplifiers. An extensive SPI port allows click-free parameter updates. The AD71028 also includes ADI’s patented multibit Σ-Δ DAC architecture. This architecture provides 92 dB SNR and THD+N of -92 dB.