To prevent this an anti-aliasing filter is used to remove components above the Nyquist frequency prior to sampling.
Choice of an appropriate sample-rate (see Nyquist frequency) is the key to minimizing that distortion.
However, considering Hales' article it could be sufficient to simply remove the Nyquist frequency.
That means to let the frequency close to Nyquist frequency be the cutoff frequency.
This representation gives a good picture of what happens around the Nyquist frequency when filtering with the low-pass filter is done.
In this period (starting about 30th second) all the harmonics, up to the Nyquist frequency, clearly follow the pattern of decreasing frequency.
Therefore strains can be measured which vary at frequencies up to the Nyquist frequency of 1 kHz.
Does anyone remember what the Nyquist frequency is?
The bandwidth of the digital system is determined, according to the Nyquist frequency, by the sample rate used.
In signal processing the critical frequency it is also another name for the Nyquist frequency.