The so-called Si-function is the pulse response of an ideal "rectangular" filter. It is also a practically ideal band-limited LF-signal which contains all the amplitudes up to cut-off frequency at (virtually) the same strength.
(a) Switch on DASYLab and select the circuit in Illustration 48. A Si-function is produced and its spectrum displayed. Using the formula component change the form of the Si-function and the effect on the spectrum by experimenting.
(b) Make sure that the ripple content of the Si-function is identical with the highest frequency of the spectrum.
(c) You wish to measure the properties of a high-quality low-pass filter but you only have a normal oscilloscope to observe the Si-like pulse response. How can you deduce the features of the filter from this?