arm_rfft_init_f32(&rS , &S_Cr, 128 ,0, 1); /* Process the data through the RFFT/RIFFT module */ arm_rfft_f32(&rS,Chebwin_Output,fft_testOutput); #endif My question is,By using RFFT Spectrum i'm seeing noise in the spectrum.why i'm seeing noise in RFFT case ?