Consider the sinusoidal signals shown in Figure 1. For the top one, the solid line represents
the continuous time signal (40 Hz sinusoidal signal) and the dots are the sampled
signals. The bottom plots show two sinusoidal signals (plotted in solid line and dash line
with 90 and 10 Hz, respectively) superimposed by dots signals that are the sampled ones.
Identify which are appropriately sampled signals, and which are not.
Frequency ambiguity effects of Eq. (2–5): (a) sampling a 7-kHz
sinewave at a sample rate of 6 kHz; (b) sampling a 4-kHz sinewave at
a sample rate of 6 kHz; (c) spectral relationships showing aliasing of
the 7- and 4-kHz sinewaves.