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10-29-2015
08:10 AM

745 Views

FFT + IFFT processing

Hello! I use FFT + IFFT pair, my adc is 12 bit and Vp 3,3 Volts, input signal is sin Amp 400mv DC offset 800mv, i have right amplitude spectrum after FFT (the square root of the sum of squares х 2, exactly DC component) .

Now i add IFFT to my project, connect source_fft to sink ifft directly and make sum scalling after ifft. assign EXP_SUM = ((~SOURCE_EXP1 + 1'b1) + (~SOURCE_EXP2 + 1'b1) - 4'd8); assign REAL_EXP = ~EXP_SUM + 1'b1; The output IFFT - sin with right frequency, but amplitude peak values is wrong, something about 2000 - 6000(the square root of the sum of squares). I'm expect values of 12 bit ADC, it's right? please help me calculate output voltage or tell what i doing wrong. mmm...if this values divide by 4 and calculate voltage (0.0008 V - 1 bit), it's will be right)))) but why?)Link Copied

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