Rapidly fluctuating battery current-draw readings

ArduPlane Plane 3.9
1

I have an Omnibus F4 Pro ver3 FC board ArduPlane V3.9.7 that I am setting up on the bench.

To calibrate the current sensor, I connected a 4.2 ohm/40W resistor where the ESC will be powered. At 12 V, this should draw about 2.8A in addition to the quiescent current (~ 0.5A) - a total of 3.3A.

However, the reading that is displayed in Mission Planner fluctuates rapidly between about 3.1A to 3.5A. When I view the battery current in the log file, this is what I see:

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which shows that the current reading is very noisy.

Is this noise due to sampling errors in the F4 ADC?

Is there any way to reduce or eliminate that noise?

2

as to my knowledge noise / sampling errors on F4 adcs are not a typical issue. shunt type resistors however typically yield limitied accuracy at low currents, that’ why http://ardupilot.org/copter/docs/common-power-module-configuration-in-mission-planner.html recommends to calibrate using at least 10A load.
most likely you won’t find any noise of that sort on other adc pins that don’t use the current shunt.