Improve the Compression Ratio by Compacting Bit-Streams and Using Modified Hadamard Transform

A modified Hadamard matrix is proposed and the compression ratio is improved by using the compatible preconditioning method on the basis of transforming and decomposing compression method. With the modified matrix to transform the energy more focused, to better match test sets, and the hardware implementation is relatively simple. With the idea of test vector compaction, input bit-streams of the circuit under test are converted to compatible before the test set is decompose, so that a number of continuously compatible bit-streams are compacted into a single bit-stream. Experiments on the Mintest test set of the ISCAS89 circuit show that both of these methods can improve the compression ratio and the hardware cost is small. The average compression rate of the VIHC coding method can reach 79.69%.