Let us assume that we obtained data sequence 
by sampling. These data are extended periodically, as shown by in the dashed curve in Figure 11.26.
by sampling. These data are extended periodically, as shown by in the dashed curve in Figure 11.26.
Figure 11.26. Sampled signal sequences
The fundamental period is 
and the fundamental frequency is 
. If this dashed curve is given as a continuous time function, its Fourier series expansion is given by the expressions obtained by replacing 
and 
in equations (11.14) and (11.15).