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Time-Frequency Reassignment
2010/11/25
林祐霆 D99945006
Reassignment
• 重新移動time-frequency plane的energy
content
• 時間的移動 和 頻率的移動
• 使用phase information : arg[ s(t,f) ]
• 提高時間解析度和頻率解析度
• 消除 Cross-terms.
Reassignment的原理
• 將能量從幾何中心移動到「質量中心」
STFT
WDF
設 w=-x 代入STFT
如何Reassignment
類比 :
舊的計算方式
• Reassigned spectrogram
令
較好的計算方式
特性
• Non Bilinearity
– 無法做 reconstruction
• Energy conservation
• Time and frequency shift
• Reassigned spectrogram的計算複雜度 :
STFT的計算複雜度 X 3 + N X N的位移
Reference
1.
F. Auger and P. Flandrin, “Improving the readability of
time-frequency and time-scale representations by the
reassignment method,” IEEE Trans. Signal Process., vol. 43,
no. 5, pp. 1068–1089, May 1995.
2. K. Kodera, R. Gendrin, and C. De Villedary, Analysis of
time-varying signals with small BT values, IEEE Trans.
Acoust. Speech Signal Process., ASSP-26(1), 64–76, 1978.
Appendix