Extraction of Feature Value in Metal Magnetic Memory Testing Based on Wavelet Packet Transform

A self-made magnetic memory test system was used to collect magnetic signals of aeronautic ferromagnetic components. Wavelet packet transform was utilized to reduce noise signals, and meanwhile, Hilbert transform was used to get the envelope curve of magnetic signals. According to experiment results, the reduction of noise was improved, and gradient eigenvalues were more exactly picked. The novel method is expected to have practical application worth.