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Viterbi Decoder

Viterbi decoder is the maximum likelihood sequence decoder for a convolutional code. In this IP core the encoder is the industry standard convolutional code of code rate R = 1/2, constraint length K = 7 and generator polynomials G0 = 133 and G1 = 171. The decoder is a soft input high throughput Viterbi decoder.

The Viterbi decoder has three functional units: the Branch Metric Unit, the Add Compare Select Unit, and the Trace Back Unit. The Branch Metric Unit calculates the four possible branch metrics based on the input symbol and the Add Compare Select Unit generates the trellis diagram. The Trace Back Unit starts from state 0 to trace back a certain amount of stages on the Trellis diagram. At the end of the trace back all the paths are supposed to have converged to the correct path. The decision bit at the end of the trace back path is the decoded data bit.

Resource usage and performance parameters are listed in table 1.

Table 1. Resource Usage And Performance Parameters

Platform CLB Slices Block Ram Clock Speed Data Rate Trace Back Length Latency Input Resolution
Virtex II 1168 4 122 MHz 122 Mbps 64 Stages 267 Clock Cycles 4 bit
Spartan III 1236 4 108 MHz 108 Mbps 64 Stages 267 Clock Cycles 4 bit

Availability And Deliverables

The Viterbi decoder is available now. Deliverables include source code in VHDL or Verilog, netlist file for Xilinx FPGA, testbenches in VHDL or Verilog, and C/C++ source code for modeling and verification.

Data Sheet

Please use the following link to down load the data sheet. Please contact us for more information.

Viterbi Decoder

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