2
\$\begingroup\$

I am trying to measure the power consumption of a low power embedded system. As the embedded system consumes current in random pulses from the battery pack, I am using an oscilloscope to analyze the signal. The blue graph represents current consumed over time.

enter image description here

I want to know how I can go ahead and find out power consumed with respect to the time varying current consumption graph.Various modules in the embedded system consumes current in varying random pulses and I have similar graphs for each operation. How can I accurately measure power consumed and eventually find energy for each specific operation?

\$\endgroup\$
2
  • \$\begingroup\$ Please scale down your images before linking to them. We don't need multiple megapixels to see a scope waveform, and if these images are inlined, it can slow the site down since the full image size has to be loaded. (I scaled and re-uploaded your picture) \$\endgroup\$
    – Adam Lawrence
    Commented Nov 4, 2012 at 23:57
  • \$\begingroup\$ @Madmanguruman Often we leave a link to the original as the click text for an image. \$\endgroup\$
    – Kortuk
    Commented Nov 5, 2012 at 2:29

1 Answer 1

Reset to default
2
\$\begingroup\$

Your Tektronix scope should have a math function. You can measure voltage and the representative current, multiply them and synthesize an instantaneous power trace. Then you can use the scope's RMS measurement capability to get average power, or just keep the peak power reading from the multiplication.

\$\endgroup\$
3
  • \$\begingroup\$ Currently I am measuring voltage across current sense resistor.I use the math variable to find the current from this. Oscilloscope is limited to one math function which prevents doing further calculations. Is there a way to find power and energy using area under the curve ? \$\endgroup\$
    – Elsa Adams
    Commented Nov 5, 2012 at 0:10
  • \$\begingroup\$ You should be able to set the probe scaling so that your representation on the screen is 1:1 with the current you want to measure, then you don't need to burn a math function. \$\endgroup\$
    – Adam Lawrence
    Commented Nov 5, 2012 at 0:11
  • \$\begingroup\$ I am not so sure about the probe scaling. I tried googling it but couldn't find much information. Any views on it would be highly appreciated. \$\endgroup\$
    – Elsa Adams
    Commented Nov 5, 2012 at 0:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.