Here is the device variance, treated the same way as the network. I have replotted the network, overlaying the smoothed curve with the original. You can tell me if you have a pref for the overlay presentation.
Note: The device variance is the time ordered sample variances of normalized trial scores for 1 minute resolution. The variance, of course,  is chi-squared (or nearly so, to the accuracy of calling the normalized trial scores normal random variables) but the degrees of freedom increases with the number of trials in a minute (i.e., increases with number of online regs). The variances are all normalized to 1, but the variance of the variances increases with df. Thus the device variance time series should be thought of as a series drawn from a changing underlying distribution. This is why the fourier components show a skew, as you can see in the plot - the values are slightly more extended to the high side of the mean (the smoothed curve gives a good indication of where the mean is).