Let’s set up an example with four channels (much of this material is taken from a real project I architected for a super-precise electricity meter built with Cypress Semiconductor’s PSoC 3).
Extreme sample converter manual sampling how to#
The error doesn’t come from the sampling process itself, but from our choice of how to interpret and manipulate the sample values.
This is equivalent to a small phase shift, which really messes up any calculation that’s sensitive to the phase difference between voltage and current (like, um, power). By pretending that you did, you’ve introduced a time delay between the voltage and the current sequences. 【Webinar】Achieving High Defect Coverage for Safety Critical and High Reliability Designsīut! If you use a multiplexed ADC, you didn’t take the voltage and the current readings at the same time. Integrate these readings over time and you accumulate the total energy.
The result, when multiplied by the length of time you assumed the samples were valid over-essentially, the sample period-gives you the energy. You sample the voltage and the current and multiply those readings together. Say you want to calculate the instantaneous energy being absorbed in an AC power circuit. If you need to do any sample-by-sample processing that involves data from more than one channel, you’re going to have to ‘pretend’ that the readings you took from different channels at different times actually happened at the same time, so that you can combine them in a calculation. So, what’s the problem sequential sampling? After all, if you’ve got, let us say, four channels that you need to sample at some rate F S, and an ADC that’ll sample fully at 4F S and that can be driven through a 4‑way multiplexer, then isn’t that a nice economical way of getting the job done? You can sample a number of analog input channels sequentially with a single ADC in such a way that the data appears to have been acquired at the same instant in time on every channel.
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