Philips Semiconductors Provides Complete Chip-Sets For Digital Video Broadcast Reception Via Cable Or Satellite

Business Wire, April 17, 1996

SUNNYVALE, Calif.--(BUSINESS WIRE)--April 17, 1996--With the explosive growth in digital video broadcasting predicted over the next few years, time-to-market and system integration will be key factors in determining success or failure for manufacturers of DVB set-top boxes and TV sets. To minimize this time-to-market, manufacturers will have to work closely with semiconductor suppliers that have total system know-how in DVB receiver design, right through from the front-end tuners that pick up satellite, cable or terrestrial signals to the digital video encoders that re-create baseband video and audio signals. On stand number 261 at Cable & Satellite '96, Philips Semiconductors is demonstrating its system know-how with a complete line up of ICs for DVB reception.

For satellite reception in the 700 MHz to 2150 MHz band, Philips Semiconductors has a new mixer/oscillator that out-performs much more expensive GaAs devices. The TDA8010AM achieves the exceptionally low levels of phase noise required to minimize the error rate in DVB receivers. Its ability to operate within the phase-locked-loop of standard TV tuners, and to cover the entire satellite band without the need for band switching, results in extremely simple and cost effective tuner designs.

Also new, the TDA8042 QPSK Demodulator and TDA8043 Digital Demodulator/Decoder provide a 2-chip solution to decoding BPSK or QPSK transmissions received by the TDA8010AM. Both ICs can handle symbol rates as high as 32 Msymbols/second. The TDA8042 includes the IF mixers and AGC circuits required to generate separate in-phase and quadrature baseband signals, which are then digitized by on-chip A/D converters in the TDA8043 Demodulator/Decoder. The TDA8043 performs all subsequent decoding of the signals into MPEG2 transport packet data.

The TDA8043 can be used in single-cast, multi-cast and simul-cast applications and is unique in being the only QPSK decoder on the market to support true variable symbol rates without any external loops. The reduction in component count that results from its unprecedented level of integration is further enhanced by the fact that no SAW filter switching is required to accommodate different symbol frequencies. In addition, all AGC, clock recovery and carrier recovery functions are performed entirely on-chip.

The equivalent decoding of DVB broadcasts received via cable is performed by Philips Semiconductors' new TDA8046H Multi-Mode QAM Demodulator. This demodulator handles all modes up to 256 QAM at symbol rates as high as 7 Msymbols/second, allowing it to be used in the latest European systems as well as in North American systems. To avoid the need for complex analog filtering, the TDA8046H features on-chip square-root raised-cosine half-Nyquist filters. These remove unwanted harmonics from the baseband signal without introducing phase errors that might otherwise affect the accuracy of symbol decoding. Another important feature of the TDA8046H is its adaptive equalizer, which cancels signal echoes without the need for training sequences to be embedded into the transmission. As a result, it can lock onto 256-QAM constellations in transmissions with signal-to-noise ratios as low as 27 dB. The TDA8046H performs well with commercially available standard tuners.

Philips Semiconductors has a wide range of high-speed low-power A/D converters suitable for digitizing the QAM signal before it is decoded by the TDA8046H. These include the 8-bit, 75-Msps, TDA8790 and the 9-bit, 30-Msps, TDA8761AM, both of which achieve the excellent linearity and signal-to-noise ratios required for low error-rate demodulation.

Any errors remaining in the demodulated data are largely corrected by Philips Semiconductors' SAA7207H Reed/Solomon Decoder and Forward Error Corrector. This IC handles DVB compliant Reed Solomon code and features automatic byte, block and frame synchronization, convolutional de-interleaving and energy dispersal de-randomizing. Its Reed Solomon decoding is implemented in three fully pipelined hardware units, each performing one of the algorithms required in the decoding process.

Whether delivered by cable or satellite, conditional access and descrambling are an integral part of modern DVB systems. These functions are performed by Philips Semiconductors' SAA7206H DVB Compliant Descrambler and SAA7205H MPEG2 Systems Demultiplexer ICs, which provide a large number of possible access filters.

Based on the Super Descrambler Mechanism algorithm, the SAA7206H performs stream and block deciphering to produce an MPEG2 data stream, and also extracts conditional access data for authentication by the system microcontroller. The deciphered MPEG2 data stream is routed to the SAA7205H Systems Demultiplexer, which separates out the relevant audio, video and teletext information. The SAA7205H accepts synchronous data from a descrambler, for which it generates a 9-MHz clock, or asynchronous data direct from a modem. In addition to outputting separate audio and video data streams, it also provides a combined audio and video data stream for the latest generation of MPEG2 audio/video decoders, such as Philips Semiconductors' new SAA7201 MPEG2 Decoder.