... | ... | @@ -23,22 +23,31 @@ We don't care of the in-band nonflatness in frequency response, so it |
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was decided to build Chebyshev filter,
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where edge sharpness is good.
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Schematic of the filter:
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Schematic of the
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filter:
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![](/uploads/34ac4da4a98a9087e2a919296c504a1c/filter_schematic.jpg)
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Simulated frequency response:
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https://www.ohwr.org/project/fmc-adc-100m14b4cha/uploads/c17e05408f3fc2465a5cec4c32618018/filter_frequency_response.jpg
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Photo of the
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filter:
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![](/uploads/40a1fe40de6a627f897a8d5ca9408fca/P1040722.JPG)
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Frequency response - marker at the frequency that is subharmonic of the
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sampling frequency (no "signal leakage" in FFT).
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Measured frequency response - marker at the frequency that is
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subharmonic of the sampling frequency (no "signal leakage" in FFT).
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This is the frequency of our desired input
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signal.
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![](/uploads/40183edda830c26609c83dfec4912084/P1040720.JPG)
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Marker at the second harmonics. Filter's attenuation at this frequency
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is 46 dB (-4 dB for the base signal
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frequency).
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![](/uploads/0c8296bbd8c6e74dc2cc9daabb13448f/P1040721.JPG)
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SUCCESS\!\!\! FFT of the filtred signal indicates the second harmonics
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