For example, if we sample the signal having components of 1, 2 and 6 kHz with a sampling frequency of 10 kHz, we have an imaginary spectrum of 4 kHz, which does not exist practically. But, if we sample it with a frequency of more than 12 kHz (
kHz)
, such an alising problem does not occur. In practical measurements, we do not commonly determine the sampling frequency by trial measurement. Instead, we use a low-pass filter to eliminate the unnecessary high-frequency components in the signal and sample with the frequency higher than twice the cutoff frequency. By such a procedure, we can prevent aliasing.
kHz)
, such an alising problem does not occur. In practical measurements, we do not commonly determine the sampling frequency by trial measurement. Instead, we use a low-pass filter to eliminate the unnecessary high-frequency components in the signal and sample with the frequency higher than twice the cutoff frequency. By such a procedure, we can prevent aliasing.