9. For decimation by D, the input spectrum of the decimator should be bandlimited to π/D, to avoid aliasing in the output spectrum.
10. The filter used to limit the bandwidth of input signal to decimator is called anti-aliasing filter.
11. For interpolation by 1, the spectrum of output signal of interpolator will have I images of input spectrum, in a period of 2π
12. The filter used to eliminate the multiple images in the output spectrum of an interpolator is called anti-imaging filter.
13. The anti-aliasing and anti-imaging filters are lowpass filters.