Time-domain Plotting

We just learned about how we can plot signals in Python and visually explore our data. We used the matplotlib library and IPython magic to plot a test signal. A test signal is a sum of various sinusoids at different frequencies, multiplied by an exponential decay function. And we can also use the package mpld3 to make it more interactive to better examine the signals and data. Next we will look at plotting specific events on top of a time series.

We just learned about zero crossings and plotting them over the time series we just created. A zero-crossing is the point in time that the signal changes sign. The zero-crossings we found aren't exactly at 0. This is because our original signal isn't continuous; it's digitally sampled! That means we didn't sample the signal exactly when it crossed zero and our zero-crossings are the closest point we have to a "real" zero-crossing.

We can visualize this by only plotting the signal points that we have and not connecting them with lines in between.