1.
Assume a Sigma-Delta ADC has a sampling rate of 1MHz. The interested signal band is
from 0 to 8kHz.
a. What value of R and C in an RC anti-aliasing filter should be used to assure that the
signal distortion within the interested band has less than -80dB.
b. Suppose there is a white noise presence between 0 to 1MHz with magnitude of 10uV
RMS. With your RC filter, what kind of extra noise level will be seen by the ADC due to
the aliasing effect?
2 .
Suppose a signal is sampled at the sampling rate Fs. Now you want to resample it at half
the rate 1/2Fs. From the lecture, one needs to insert a low pass filter with cut off
frequency at ¼Fs and beyond before the down sampling. This combined process is called
decimation. Please explain why the low pass filter is needed.
谢谢您通俗的解释. |
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