Xilinx V2.1 Depuncture, Xilinx System Generator v2.1 Reference Guide, Xilinx Development System

Models: V2.1

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Depuncture

Xilinx System Generator v2.1 Reference Guide

Depuncture

The Xilinx Depuncture block allows you to insert arbitrary symbol into your input data at the location specified by the depuncture code and creates a new value. This value is presented as output from the block. The Xilinx depuncture block accepts data of type UFixN_0 where N

equals the length of insert string x (the number of ones in the depuncture code) and produces output data of type UFixK_0 where K equals the length of insert string x (the length of the depuncture code ).

The Xilinx Depuncture block can be used to decode a range of punctured convolution codes. The following diagram illustrates an application of this block to implement soft decision Viterbi decoding of punctured convolution codes.

Figure 3-32: Example of Depuncture block use

The previous diagram shows a matched filter block connected to a serial to parallel block. The serial to parallel block concatenates two continuous soft inputs and presents it as a 6-bit word to the depuncture block. The depuncture block inserts the symbol '100' after the 3-bits from the MSB for code 0 ( [1 0 1] ) and 6-bits from the MSB for code 1 ( [1 1 0] ) to form a 9-bit word. The output of the depuncture block is serialized as soft decision 3-bit input words for the Viterbi decoder which decodes the punctured convolutional code and outputs the decoded data.

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Xilinx Development System

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Xilinx V2.1 manual Xilinx System Generator v2.1 Reference Guide, 32:Example of Depuncture block use