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題 名 | 一個適用於近似週期信號的新自適性向量量化法及其在心電圖資料壓縮上的應用=A Novel Adaptive Vector Quantization Scheme for Quasi-periodic Signals and Its Application to ECG Data Compression |
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作 者 | 繆紹綱; 藍仁宏; | 書刊名 | 中華醫學工程學刊 |
卷 期 | 19:4 1999.12[民88.12] |
頁 次 | 頁253-261 |
分類號 | 410.1644 |
關鍵詞 | 近似週期信號; 心電圖資料壓縮; 自適性向量量化; 碼向量間的冗餘性; Quasi-periodic signals; ECG data compression; Adaptive vector quantization; Codevector redundancy; |
語 文 | 中文(Chinese) |
中文摘要 | 近似週期信號可視為一個有週期及振幅變動的週期信號。本文探討以向量量化法 對近似週期信號做資料壓縮的問題,其中週期性帶來二維碼簿儲存空間浪費的效應,振幅變 動則帶來碼簿適應性降低使得品質下降的效應。 傳統的向量量化( VQ )具有固定的碼向量,因此無法適應各種不同的信號,造成所謂訓練 集和測試集不匹配的問題,因此有人提出自適性向量量化( AVQ )。 此外,對於近似週期 信號, 用傳統二維碼簿的 VQ 或 AVQ 均易使碼簿中的碼向量間產生冗餘性,造成儲存空間 的浪費,並增加硬體製作上的成本及困難。因此本研究提出一維條狀碼簿架構為基礎的自適 性向量量化法來進行近似週期信號的資料壓縮, 此方法稱為一維 AVQ 或簡稱 1D-AVQ。 1D-AVQ 除可降低傳統 VQ 中碼向量間的冗餘性及訓練集與測試集不匹配的問題外, 還可控 制重建信號的品質。 對 1D-AVQ 及一種稱之為 GW-AVQ 的二維碼簿方法,以 MIT/BIH 資料 庫中 3 組特性明顯不同的心電圖資料來進行實驗比較。 結果 1D-AVQ 都比 GW-AVQ 有較佳 的編碼表現,更重要的是碼簿的儲存空間只約需其 1/12 ∼ 1/6,因此 1D-AVQ 極適合在有 記憶體容量限制的 DSP 單晶片處理器上實現。 |
英文摘要 | A quasi-periodic signal is a periodic signal with period and amplitude variations. In this paper, we investigate the problems of using vector quantization (VQ) for the data compression of quasi-periodic signals. It is found that the periodicity of the signal introduces a waste of the storage space for traditional two-dimensional (2D) codebooks and the amplitude variation causes the quality degradation of the signals. The fixed codevectors in traditional VQ result in no adaptation to various signals, creating the problem of incompatibility between training and testing sets. One useful solution to this problem is the use of adaptive VQ or AVQ. In addition, the quasi-periodic characteristic of a signal will create the data redundancy among codevectors in the 2D codebook. Consequently, the storage space is wasted, the cost and the difficulty in hardware implementation are increased as well. To solve these problems, we propose a novel AVQ scheme called 1D-AVQ based on a onedimensional (1D) codebook structure. The 1D-AVQ scheme not only can reduce the codevector redundancy but can also control the quality of reconstructed signals. The 1D-AVQ and a 2D-codebook based AVQ method called GW-AVQ are used to test on three different records of ECG signals from the MIT/BIH database. The experiment shows that 1D-AVQ is better than GW-AVQ in coding performance and most importantly, the codebook storage requirement is around 1/12∼1/6. Therefore, 1D-AVQ is more suitable for the implementation on a memory-limited DSP processor. |
本系統中英文摘要資訊取自各篇刊載內容。