 If you need deeper reduction ratio, you need longer bit length for the filter coefficients. So let's change it to "20".
Then the reduction ratio has become at least -90dB.
U_5's spectrum says 3kHz has been decreased -90dB or more.
You can save the quantized coefficients by choosing "Tools" -> "Save Coefficients" on the menu when U_6 window is enabled. Data formats are Real, Bin, Dec, Hex.
That's it for this class. A digital filter accumulates quantization errors.
So even if the coefficients consist of 16bits, the reduction ratio could
not be -96dB (= 6.02 x Bit length). I think the coefficients need more than
20bits for -96dB reduction ratio.
See also this class to see how to quantize a signal.
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