What is the time accuracy of data recorded with the Nordic Power Profiler Kit II?

RE: What is the time accuracy of data recorded with the Nordic Power Profiler Kit II?

Alphanoob — Wed, 18 Sep 2024 17:33:06 GMT

Hello PaKa,

thanks a lot for that hint. I will look into the number of packets in order to check for any lost data. The accuracy I need is in the range of about 5 %. So I will be able to trust the PPK 2 data (of course not to the same extent as calibrated lab equipment but in I should be able to see functional issues with the device under test resulting in a wrong timing).

tesc : Since toggling GPIOs/voltages is not an option for my measurement I do have to rely on current measurement. So far I was not able to get my hands on "high-quality lab equipment" for measuring currents less than 1 mA with a time resolution better than 50 kHz and a specified clock accuracy. Even the big-brand power analyzers I looked at so far don't specify their clock accuracies.

Thanks!
Alphanoob

RE: What is the time accuracy of data recorded with the Nordic Power Profiler Kit II?

PaKa — Wed, 18 Sep 2024 07:53:06 GMT

The timing of the PPK measurements are controlled by the crystal on the device so as long as you don't have any packet losses you should be in >>>1% accuracy. I would expect this to be in the PPM range but as there is SW on top there is always the possibility for skews. Note: this is with no packet loss so you should check that the number of samples you have match what the time period measured should contain if you feel the data seems unlikely.

RE: What is the time accuracy of data recorded with the Nordic Power Profiler Kit II?

tesc — Tue, 17 Sep 2024 14:34:06 GMT

Hi,

I am afraid we do not have numbers for the accuracy of the time difference between two current samples in the measurement data. What we do have, is the ±20 % accuracy of average current measurement, of which the time domain would be a factor. From that it follows that expected time accuracy is also within ±20 %.

Please note that the Power Profiler Kit II, while a good tool for measuring power consumption during development, does not replace high-quality lab equipment. For timing measurements, the recommendation is to toggle a GPIO and use proper lab equipment (e.g. oscilloscope, logic analyzer) with the wanted time accuracy.

Regards,
Terje