Demodulator IC ensures solid in-car DVB-T reception.
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Press Release Summary:
Incorporating Maximum Ratio Combining technology, mixed-signal Model DRX 3976D allows for sophisticated processing of COFDM signals received simultaneously by multiple antennas. It includes progressive channel estimator with diversity interface. Implemented digital filtering algorithms comprise movement estimation with adaptive prediction and interference detection. Two or more DRX 3976Ds may be daisy-chained directly using diversity I/O ports of chip.
Original Press Release:
Micronas' New Diversity Demodulator With True-Adaptive MRC Ensures Solid In-Car DVB-T Reception
Micronas 4th generation COFDM demodulator DRX 3976D facilitates automotive DVB-T applications due to a unique implementation of the Maximum Ratio Combining technology patented by R&S
Freiburg, Germany, November 09, 2004 - Micronas (SWX Swiss Exchange: MASN, Frankfurt: MNSN, Prime Standard Segment, TecDAX), today announced the launch of a new COFDM (coded orthogonal frequency division multiplex) demodulator IC, the flagship of the Micronas 4th generation demodulator series. The DRX 3976D is designed to support so-called diversity techniques using two or more antennas which ensure optimum reception quality in car entertainment applications. The mixed-signal IC incorporates Maximum Ratio Combining (MRC) technology licensed to Micronas by Rohde & Schwarz. It allows for sophisticated processing of COFDM signals received simultaneously by multiple antennas while yielding a superior signal quality, even under specific in-car reception conditions.
"When receiving DVB-T in a moving car, the receiver must be able to handle fast channel variations and deep fading effects. A glueless interface between two or more DRX 3976D devices with true-adaptive Maximum Ratio Combining algorithms allows a smooth implementation and the best possible reception under all conditions." says Wladimir Punt, marketing manager of digital TV at Micronas Holland. He believes that, "The market for in-car TV reception will expand exponentially by using true-adaptive Maximum Ratio Technology for DVB-T reception."
Tomo Mlakar, Director of Standardization and Development Support, Rohde & Schwarz, adds: "Maximum Ratio Combining has been proven to be a successful architecture for in-car DTV reception and we are pleased that Micronas is licensing our patented technology in their true-adaptive MRC solution."
The heart of the DRX 3976D is the progressive channel estimator with a diversity interface. The implemented digital filtering algorithms comprise movement estimation with adaptive prediction and interference detection. The benefit is that the quality of the channel analysis is extremely high, resulting in strong, general COFDM Demodulation behavior in dynamic environments, and also in very precise signal reliability information per data carrier. This data is used by the true-adaptive MRC function to join the data carriers for optimized, distortion-free reception. Two or more DRX 3976Ds may be daisy-chained directly using the diversity I/O ports of the chip. Moreover, the DRX 3976D allows both the diversity-data-output bus and the MPEG2-TS output bus to be active simultaneously. The DRX 3976D's may operate individually, such as one for single-antenna reception and one for a band-scan action. This will take place from time-to-time when driving, in order to re-locate the channels.
A complete in-car audio/video entertainment system can be easily assembled in combination with other Micronas products, such as the DRX 3960A for analog TV reception, the MDE 9500B hybrid decoder, the MSP 44xyG stereo/sound processor and the DPS 9455B LCD panel driver.
The DRX 3976D is housed in a 14 x 14 mm² 80 pin PMQFP package. Engineering samples as well as an evaluation kit with high level software drivers will be available from December 2004 with mass production ramping up in the second quarter of 2005.
Background information
Although DVB-T has been developed to cope with severe channel conditions, it was originally not intended to cover all of the specific characteristics of mobile reception. A car TV receiver, as well as a portable indoor unit, typically receives many multi path signals. For portable indoor reception, such dynamic echoes may be caused by people or objects moving in the room. This results in deep fading or even flat fading effects of the selected channel [flat fading = complete cancellation of the desired channel]. Additionally, the movement of the receiver causes so-called Doppler effects, distorting the DVB-T channel information, based on the speed of the mobile receiver and the DVB-T transmission frequency and the direction of the incoming echo. Each multi path signal to the receiver will be influenced by this Doppler Effect, resulting in a complex, time-varying channel shape.
Diversity techniques significantly improve reception performance by using two or more antenna / demodulator combinations. A diversity system uses the information of each demodulator and obtains for each data-carrier of the COFDM signal the best possible quality. In case one antenna is experiencing poor reception conditions, for example deep or flat fading, the other antenna(s) will probably receive a better signal. By continuously combining the antenna information at the correct moment by the correct weighting, a diversity receiver will deliver an optimal output signal.
