Reconstruction of Low-Frequency and High-Frequency Coefficients at Each Level with Wavelet Packet Analysis

This program is designed to reconstruct low-frequency and high-frequency coefficients at each decomposition level and generate corresponding power spectrum plots. The x-axis represents frequency, while the y-axis indicates power values. The implementation involves wavelet packet decomposition algorithms to extract signal components across different frequency bands. Key technical aspects include: - Applying wavelet packet transform to decompose signals into multiple frequency subbands - Implementing reconstruction algorithms to restore coefficients from different decomposition levels - Calculating power spectral density using Fourier transform or Welch's method - Utilizing tree structure visualization to display the hierarchical relationship between wavelet packet nodes In the final stage of wavelet packet decomposition, the program displays the four-level decomposition tree structure, providing clear visualization of data details and hierarchical relationships. This helps analyze signal characteristics across different frequency resolutions and decomposition paths.