參數(shù)資料
型號(hào)： L64781
廠商： LSI CORP
元件分類： 消費(fèi)家電
英文描述： SPECIALTY CONSUMER CIRCUIT, PQFP100
封裝： PLASTIC, QFP-100
文件頁數(shù)： 46/164頁
文件大小： 2003K
代理商： L64781
1-2
Introduction
including a COFDM DVB-T/ETSI-compliant demodulator and a
concatenated FEC decoder. The input/output format and pin-outs
simplify the direct interconnection of the L64781 to the L64x08 (the
MPEG-2 transport stream chip from LSI Logic) through synchronous
serial or parallel MPEG-2 transport stream interface.
The DVB-T/ETSI specication incorporates many modes, providing a
wide range of capacity/performance trade-off options.
Terrestrial transmission paths are prone to multipath, which can result in
“ghosting” on analog television pictures. With conventional methods of
digital transmission, multipath causes inter-symbol interference. This
becomes increasingly problematic as the bit rate increases.
The DVB-T/ETSI specication uses a special form of modulation that
uses Coded Orthogonal Frequency Division Multiplexing, which is well-
suited to channels with signicant multipath. It can tolerate signals with
long delay and high relative amplitude. Consequently, the L64781 can
accommodate natural multipath (from terrain, buildings, etc.) and it can
be used in a Single Frequency Network (SFN). In an SFN, many
transmitters operate on the same frequency with the same modulation
(used in Digital Audio Broadcasting, which also uses COFDM). The
DVB-T/ETSI specication includes modes suitable for SFN operation.
In the frequency domain, multipath can be seen as channel frequency
selectivity. COFDM applies concatenated FEC coding, then distributes
the coded data over many carriers (1705 or 6817 in this case, depending
on the mode). At the receiver, the frequency selectivity of the channel
causes some carriers to be degraded or suppressed. However, the
receiver can determine how much each carrier is affected by noise, then
pass this information to the inner-code Viterbi decoder by means of soft-
decision bits. This allows the Viterbi decoder to decode the data more
efciently. A second decoder, for the Reed-Solomon FEC, completes the
process. In a similar way, COFDM can also cope with interfering signals
which are localized in frequency.
1.2 Using the L64781 Chip in a Receiver
The L64781 chip provides maximum integration and exibility for system
designers at a minimum costs. It contains an on-chip 10-bit analog-to-
digital converter (ADC). Minimal external components are needed to
l64781.book Page 2 Friday, January 19, 2001 1:28 PM
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L64782 制造商:未知廠家 制造商全稱:未知廠家 功能描述:L64782 Single-Chip COFDM Receiver
L6480 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:The L6480, realized in analog mixed signal technology, is an advanced fully integrated solution suitable for driving two-phase bipolar stepper motors with microstepping.
L64801GC-20 制造商:未知廠家 制造商全稱:未知廠家 功能描述:32-Bit Microprocessor
L64801GC-25 制造商:未知廠家 制造商全稱:未知廠家 功能描述:32-Bit Microprocessor
L64801GM-20 制造商:未知廠家 制造商全稱:未知廠家 功能描述:32-Bit Microprocessor
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