Here is the magnitude and the phase of the line spectrum of the average V(3,3) EKG signal:
Note that while the magnitude of the spectrum appears to be "well behaved", the phase of the spectrum appears to be random. Furthermore, there appears to be no discernable difference between the phase at each 1 Hz interval (the "lines") and that in between the 1 Hz intervals (at which the magnitude drops to zero).
In order to better visualize the phase, and to reconstruct the signal based on a Fourier series, both the magnitude and the phase are sampled at 1 Hz intervals to produce the following tables of values. In this case, each 1 Hz interval peak comes every 64 pts in each plot.
Here are magnitude/phase and real/imaginary plots of these tables of values:
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