一種不用乘法器的增量調(diào)制DFT新結(jié)構(gòu)
A NEW MULTIPLIER-FREE STRUCTURE FOR DFT BASED ON DELTA MODULATION
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摘要: 本文提出一種基于增量調(diào)制(DM)序列的離散傅里葉變換(DFT)結(jié)構(gòu),它不同于基于脈沖編碼調(diào)制(PCM)的常規(guī)方法。提出這一想法是為了解決在常規(guī)的數(shù)字信號處理中的乘法運算問題,從而減小系統(tǒng)的復雜性,降低設備成本。我們將看到,本文提出的新的DFT結(jié)構(gòu)取消了A/D變換器和乘法器,可望簡化硬件設計、降低造價,而信噪比同樣能夠達到與常規(guī)的處理方法,如FFT相近的結(jié)果。計算機模擬表明,對于確定性信號,結(jié)果與常規(guī)的DFT相一致。對于帶限高斯信號,只要適當?shù)剡x擇步長和過采樣率系數(shù),同樣也能得到與常規(guī)DFT相近的結(jié)果。我們采用ROM存貯各個系數(shù)值,因此,整個運算完全是閱讀和求和的過程,因而速度快,硬件結(jié)構(gòu)簡單,適用于語音、地震等信號的處理。本文最后給出了硬件實現(xiàn)方案和各個參數(shù)的選擇方法,同時提供了計算機模擬結(jié)果。
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關(guān)鍵詞:
Abstract: A new implementation of the DFT based on delta modulation (DM) is proposed. It is different from the conventional implementation based on PCM. The hardware structure of the method is constructed without A/D converter and multiplier, so it is simpler and of lower cost. Its SNR can approach that of the conventional one, such as FFT. Computer simulations demonstrate that for deterministic signals, results obtained agree well with theoretical analyses, for band-limited Gaussian signals; if step size is suitably selected, results similar to the conventional DFT can still be obtained. Because of the limitation of the working speed of the device, this method will be suitable for processing speech and seismic signals. Finally, the hardware structure which simply consists of a ROM, an adder and some other auxiliary circuits is given. -
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