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Micsig Current Probe CP2100A/B Tests and Comparing

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Algasman:
The signal was unbiased, so it should include both. I put my gear away, but if I give it another try, I could measure the rising and the falling delay.
The 10mA offset was an oscilloscope issue, both channels were AC coupled. The offset did not affect the measurement, I checked that.

rhb:

--- Quote from: RobbiTobi on March 19, 2021, 06:11:55 pm ---You have to distinguish two facts:
1. the current probe has a physical signal delay, which is a constant delay as specified in the specs (here <150ns)
2. the phase-shift or phase-error is a function of frequency due to the signal processing chain (filters and more...)

You can compensate the constant signal delay i.e. by the CHskew setting of your scope - this is correct.
However, the phase-shift you can hardly compensate - only in the case you work with simple CW signals like a pure sinusoid.
As soon as you are dealing with complex signals like i.e. a square-wave you get a signal composed of harmonically related sinusoids with different frequencies (see Fourier series).
Your measured signal of the probe will get shifted and distorted due to the phase-shift error vs. frequency.
In that case you hardly can compensate the phase-shift of each sinusoid component and your procedure as described will not work anymore.

--- End quote ---

Once it has been digitized you can correct phase and amplitude errors with DSP to a high degree of accuracy.  This is essentially no different from calibrating an analog  SA/TG or  VNA.  For an SA/TG, you store a thru cal and apply that.  Then any difference is device error.  The cost is 2 FFTs and  a multiply.  Something an FPGA can do *very* fast at typical sweep lengths.  This yields sampling as the limiting variables, sample rate and # of bits.

Take a look at this:

https://www.eevblog.com/forum/testgear/a-high-performance-open-source-oscilloscope-development-log-future-ideas/msg3326904/#msg3326904

We've had hours of discussion about what can be done via DSP on an FPGA.  I have extensive seismic DSP experience.  There is very little cost to doing two FFTs per trace window and a multiply per frequency.  And once you've got a signal in both time and frequency you can do anything quite cheaply.

Ideally you would load FPGA images from flash memory which could be loaded to the fabric in any order and with any connections so that one can form arbitrary pipelines.  This allows writing highly specialized fabrics for triggers and other cool stuff.

Have Fun!
Reg

Peter_O:
Just got a CP2100A. For my very basic purposes this 800kHz version is fine.



The last posts about phase shifts are many months old, but nevertheless:
Here's a quick bode plot of my CP2100A, showing the phase shift.


100kHz square wave, magnitude of 200ns rise time well within spec.
(F1 blue: average n=128)

 

A very basic test with a 60W light bulb:



DMM shows 255.6 mA
Micsig shows RMS 258.6 mA




And a shot of a PC power supply starting into standby with about 20A within the first half wave. Micsig in 100A mode.






Curious:
Apologies, waking up an old post...

Can anybody help translate MicSig's specified Accuracy, identical language for CP2100A & B.  It's entitled "DC accuracy" but then uses "Apk" which I assume means "Amperes Peak", which wouldn't be DC.

DC accuracy (typical)     
3%±50mA (10A)                          {I'm guessing this line is DC, on 10A range, but no equivalent for 100A range}

4%±50mA(100A,500mA~40Apk)  {maybe AC accuracy if Amps peak is <40Amps, up to bandwidth limit  .8 or 2Mhz}

15%(100A,40Apk~100Apk)     {maybe AC accuracy if Amps peak is >40Amps, up to BW  .8 or 2Mhz.  saturation of steel core??  so reads lower than reality}       

ceut:
Hello,
I have received my Misig CP2100B.
It is really a great current probe  :-+

Some photos, because it seems to be a new 2024 batch:
- wire is not a big grey for the clamp, but thin soft black
- piece of rubber to hold the cable
- the in/out of the wires are rigid plastic part  :(

I have also checked the power consumption on RD6006P with its great calibration  ;) : it is really low  8) 0.044mA
And it seems the relay may be a 2 coil-latching one, because there is only a very short peak of current when switching at about 0.15A, then come back to 0.044mA



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