I have two voltage signals (both 400 kHz), one is approx 1 Vrms (output from Pearson current montior, 1A = 1V), the other approx 0.5 Vrms (output from Tek 1000:1 voltage probe). I need to divide these two signals (V/I) to display impedance real time (updating at least 2 Hz). It is a purely resistive circuit. I have both a TEK TDS2014 o'scope and an Agilent 34401A multimeter available with windows based data aquisition software. Should be simple, but not being a programmer, I can't seem to find a way to do this. Thanks for any help.
Impedance calculation
Dec 15, 2005
4 Replies
does the scope support math functions that would let you do trace A / Trace B? I know that the TDS 3014 that I have does.
Unless the resistance is variable, Z will be constant, so one V/I reading is all you need. Do you know: 1)how to get your two voltages into your windows program as numbers accurately representing the voltage and current measurements; 2) how to get your program to divide the two numbers; 3) how to get your program to present the result; and, if necessary (because the resistance varies) 4) how to get your program to loop back to 1) ?
Ed
Good point that I should have stated up front. The impedance is continuously varying between approx 50 and 200 ohms. I'm familiar with the process of capturing waveforms from an o'scope to a pc, then exporting the data to excel, etc., but in this case I need to have continuous instantaneous impedance feedback. Thanks anyway, though!
Unfortunately, no. The TEK 2000 series only has + - x math functions. Actually, I'm trying to get a 3000 series in as a "demo / loaner" to try out the division function. Surprising that very few o'scopes come with a division math function; maybe because of "divide by zero" error problems?
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