I have a circuit fed from a 14 to 37V DC feed. The circuit naturally uses between 20 and 80mA however it musn't present more than a 20uA ripple current to the feed incase it corrupts communication on the line. I have used a shunt regulator to try and control the current and the normal array of caps to help smooth the current usage.
My question is what would be a valid way to measure that I have achieved a20uA range, Is just inserting a DVM set to AC current sufficient or is it likely to distort the results with any internal resistance it may have. The DVM I am using is an old TTI 1905a although it is still within calibration.