Chinese digital terrestrial television demodulator design of the program – digital TV, chip, high-de
Abstract: The main challenge of chip design is always to provide superior performance and a relatively low cost products. The DTMB standard that is more complex, not easy to do this, need to consider carefully which features are useful and can solve real problems encountered. When the DTMB and DVB -T, ATSC and ISDB-T for comparison, DTMB in a cost disadvantage in the receiver. Therefore, the design focus is not only how to reduce the cost of demodulator chip, while the receiver is how to reduce the overall cost.
China since 1996 on international Digital TV Terrestrial broadcasting technology tracking. After years of unremitting efforts, China in August 2006 issued the “digital terrestrial television broadcasting transmission system frame structure, channel coding and modulation” standard (also often known as DTMB, the standard number for the GB20600-2006), and is scheduled from August 2007 officially mandatory implementation.
Ground GB transfer technology in the use of advanced channel coding techniques, combined with the time domain and frequency domain channel synchronization and equalization, and volume data using clever frame structure, made in a number of technical breakthroughs, a truly complete independent intellectual property rights innovation system.
2008 1 1st, Hong Kong SAR was the first Chinese-based transmission standard for digital terrestrial television broadcasting business operations. May 1, 2008, “CCTV HD “HD channels, formally launched, marking the ground-GB technology into the formal implementation stage. In SARFT Under the guidance of China, including Beijing, Shanghai, Shenzhen, the “6 +2″ a city learn from the Beijing Olympics terrestrial test Test And practical experience, launching the “CCTV HD” high-definition broadcast services and local television broadcasts.
Domestic TV and STB Companies after years of waiting, finally started the substantive products related products design and mass production.
DTMB standard of review Can see the standard text, DTMB standard is a single-carrier systems and multi-carrier systems integration products. Carrier numbers, PN type, constellation points, NR coding and LDPC coding rate, interleaving depth and other parameters derived from 330 kinds of options for a total portfolio. However, some parameters of options is obviously some kind of carrier modulation to set up and will apply them to another carrier debug mode is not meaningful. 330 species in this model, about 260 species that we think of practical value. In fact, the relevant departments to study and formulate a “common standard terrestrial digital TV receivers,” of which only 7 models were required. Reduction mode helps reduce industry costs and quickly achieve the program into practice.
DRX398yZ system block diagram.
DTMB signal for each frame are used for synchronization and channel estimation of the PN sequence, and data loading components. Single-carrier mode, the data load modulation in the time domain, while the multi-carrier mode, the data load modulation in the frequency domain. For the standard multi-carrier section, using frequency domain processing is the traditional solutions, which makes the spectrum associated with various types of channel distortion (such as simulation of interference with the frequency, single frequency interference, etc.) can easily be detected, suppression or compensation . For the standard single carrier part, the best use of time-domain decision feedback Equalizer In order to detect the relevant time-domain distortion (such as echo, jitter, etc.). The operational not only based on PN sequences, and some of the data load can continue. While such time-domain equalizer to achieve the cost may be higher, but their performance is good, or value for money.
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