If you’ll pardon the cliché, the proof of the pudding is in the eating. Figures 6 and 7 are “before and after” plots for a segment of data from a four-channel .wav file acquired from a multiplexed-ADC project built on a PSoC3 development board. The source signal consists of equal amounts of 50 Hz and its first 21 harmonics, phased randomly. It was generated by playing out a synthesized .wav file through a PC’s line output, and applied to the four multiplexed inputs (through carefully matched input AC coupling networks). We took a lot of care to ensure that everything on one channel settled really well before switching over to the next multiplexer channel (otherwise you get crosstalk, which can cause significant accuracy problems in a meter). Because the four channels aren’t sampled at the same time, the data points for the four streams plotted in Figure 6 aren’t identical. This extreme waveform was chosen to make a visual point, even though it would be a rather unusual signal to apply to an actual electricity meter.
Closer detail of the passband gain and the different group delay values