参数资料
型号: L64781
厂商: LSI CORP
元件分类: 消费家电
英文描述: SPECIALTY CONSUMER CIRCUIT, PQFP100
封装: PLASTIC, QFP-100
文件页数: 95/164页
文件大小: 2003K
代理商: L64781
2-16
Architectural Overview
according to an algorithm dened in the DVB-T specication. It then
passes one symbol’s worth of reordered data onto the bit deinterleaver.
Echoes cause minimal (“holes”) in the received spectrum, leading to
groups of carriers on which the data is unreliable. For optimum operation
of the Viterbi decoder, these groups of unreliable carriers must be split
up. The symbol deinterleaver fullls part of this function, and the bit
deinterleaver performs the remainder.
2.16 Bit Deinterleaver
In the presence of multipath or interference, some COFDM carriers
convey data less ruggedly than others. Each COFDM carrier supplies
two, four, or six soft decisions. These are impaired if they came from an
impaired carrier. For optimum operation of the Viterbi decoder, groups of
unreliable soft decisions must be spaced as far apart as possible. The
purpose of the bit deinterleaver is to split up unreliable soft decisions
caused by a single unreliable COFDM carrier. The symbol deinterleaver
does the task of separating groups of unreliable COFDM carriers.
The bit deinterleaver accepts groups of 3- or 4-bit soft decisions
generated by the same COFDM carrier from the symbol deinterleaver; it
then rearranges these groups so that soft decisions generated from the
same carrier are separated.
2.17 Demux Output Format (DOF)
The
demux output format (DOF) block formats soft decisions for
presentation to the Viterbi decoder and/or to the output interface of the
L64781 for external decoding (output signals SOFT_BPSK[3:0]). The
overall process is split into hierarchical and nonhierarchical transmission
modes.
In nonhierarchical mode, a single-bit stream is sent to the on-chip Viterbi
decoder. In this case, the output signal SOFT_BPSK[3:0] is in 3-state.
l64781.book Page 16 Friday, January 19, 2001 1:28 PM
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L64782 制造商:未知厂家 制造商全称:未知厂家 功能描述:L64782 Single-Chip COFDM Receiver
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