September 4, 1996
National Semiconductor Corporation has announced an integrated solution for cable modems and set-top box systems.
The NDV9022 16/64 QAM Digital Demodulator plus Forward Error Correction (FEC) Decoder is the first major new product in National's comprehensive program to deliver a full family of optimal system solutions for the next generation of digital set-top boxes and cable modems. The device is a programmable 16 or 64-QAM demodulator with adaptive equalization and FEC optimized for high performance yet low cost in cable modems and digital Cable TV (CATV) receiver applications. It is available in two speeds, the NDV9022A for 8 MHz TV channel applications (PAL/SECAM for Europe and Japan) and the NDV9022B for 6 MHz TV channel applications (NTSC for North America).
According to Douglas McBurnie, senior vice president of National's communications and consumer division, "Quadrature Amplitude Modulation or QAM technology is key to digital set-top box implementation because it allows existing analog transmission media, such as coaxial cable, to carry digitally compressed information. Such digital compression of video and audio data can allow an analog system to carry up to five channels of information in a single 6 MHz channel space. As a result, traditional cable systems with approximately 100 channels can be boosted up to 500 channel capacities which will open the door for Video on Demand and high-speed Internet access services directly into the home."
Mr. McBurnie went on to say, "National's traditional strengths in analog and mixed-signal design plus our 0.35 micron CMOS manufacturing capabilities have allowed us to develop a state-of-the-art 16/64 QAM integrated solution with built-in Forward Error Correction that is targeted for use with existing CATV transmission standards. Combined with other National components, the NDV9022 provides the core for designing a high-speed cable modem and set-top box systems."
QAM (Quadrature Amplitude Modulation) refers to a signal-modulation scheme that dial-up modems and broadband networks use to increase data traffic by packing multiple bits into a single symbol period. The QAM designation, such as 16 QAM, 64 QAM, etc., refers to the size of the signal constellation, e.g. the 16 QAM has 4 bits per symbol whereas the 64 QAM increases the data stream up to 6 bits per symbol. QAMs are basically multi-processor hardwired DSP engines working in parallel to provide the needed processing power. For instance, a 64 QAM design requires in excess of 1 Giga-operations per second.
The NDV9022 is a highly integrated 16/64 QAM device which integrates all of the baseband signal processing functions, such as 64 QAM demodulation, adaptive equalization, and on-chip timing and carrier recovery. Because the NDV9022 directly processes IF data, no external analog components are required to do I/Q splitting. The NDV9022 performs digital quadrature detection on IF data resulting in precise I/Q amplitude and phase. This all-digital acquisition and tracking allows the NDV9022 to acquire and demodulate signals under severe CATV transmission conditions, such as phase noise, micro-reflections and multi-path distortions. In addition, the NDV9022's high level of integration simplifies system design and reduces cost by eliminating the need for external I/Q splitting or timing/recovery VCXOs while at the same time allowing it to operate with inexpensive off-the-shelf analog TV tuners, A/D converters and other components.
The NDV9022 also integrates on-chip the complete Forward Error Correction (FEC) decoding function for a DVB compliant CATV receiver, including MPEG sync byte detection, de-interleaving, Reed-Solomon decoding and descrambling. In a typical application, the NDV9022 is programmed to receive and demodulate a 41.4 Mbps data stream, encoded into 64-QAM symbols at 6.9 Msymbols/sec. To meet the very demanding bit error rate requirements of digital TV, the NDV9022 is designed to accommodate the noise, distortion, reflections and phase jitter from a worst case HFC, tuner and IF/AGC transmission channel.
The NDV9022 is manufactured using an advanced CMOS process and requires only a single 3.3 volt supply. Designed for easy integration with existing standards and tuner components, it includes an on-chip signal level estimator and AGC controller to provide a feedback loop for tuner/IF automatic gain control. In addition, many of the NDV9022's parameters can be programmed via the built-in M-Bus serial interface.
Price & Availability
Samples of the NDV9022 will be available to Alpha/Beta sites in Q1/97 with general sampling in Q2/97. Housed in an 84-pin PLCC package, the device will be priced at $32 in 10K quantities.
National Semiconductor Corporation provides Technologies For Moving and Shaping Information. The company focuses on four strategic markets: communications, personal systems, industrial, and consumer. National Semiconductor is headquartered in Santa Clara, California, and has 20,000 employees worldwide. In fiscal 1996, the company reported sales of $2.6 billion.