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CRO probes calibration

pradeepa kumar

Nov 4, 2014
2
Joined
Nov 4, 2014
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2
Hi, can anybody tell me how to calibrate a CRO probe? Also, is calibrating and compensating the probe both same? Kindly reply if you know about it. Thank you.
 

hevans1944

Hop - AC8NS
Jun 21, 2012
4,878
Joined
Jun 21, 2012
Messages
4,878
Most CROs have a fixed-gain or CAL position on each input channel sensitivity control. An internal calibration potentiometer can tweak the CAL position to produce a specific sensitivity, such as 20 mV per division. Many CROs provide a square wave signal to check the CAL position sensitivity, but that too needs calibration (infrequently) by an instrument calibration service.

Compensating a probe applies only to probes that provide attenuation of the input signal, typically 10X and 100X attenuation. Compensation is not the same as calibration. Compensation (or frequency compensation) is a capacitor adjustment that allows the probe to pass a band of frequencies without appreciable attenuation discrepancies as a function of frequency. You make the adjustment by connecting the probe to a fast rise-time square-wave signal source, adjusting the compensation capacitor for maximal flatness of the waveform, neither over-shoot nor rounding the edges of the pulses. There usually is no attenuation calibration adjustment. You can determine the actual probe and CRO sensitivity if you have a square-wave pulse generator whose peak-to-peak amplitude is accurately known.
 

pradeepa kumar

Nov 4, 2014
2
Joined
Nov 4, 2014
Messages
2
Most CROs have a fixed-gain or CAL position on each input channel sensitivity control. An internal calibration potentiometer can tweak the CAL position to produce a specific sensitivity, such as 20 mV per division. Many CROs provide a square wave signal to check the CAL position sensitivity, but that too needs calibration (infrequently) by an instrument calibration service.

Compensating a probe applies only to probes that provide attenuation of the input signal, typically 10X and 100X attenuation. Compensation is not the same as calibration. Compensation (or frequency compensation) is a capacitor adjustment that allows the probe to pass a band of frequencies without appreciable attenuation discrepancies as a function of frequency. You make the adjustment by connecting the probe to a fast rise-time square-wave signal source, adjusting the compensation capacitor for maximal flatness of the waveform, neither over-shoot nor rounding the edges of the pulses. There usually is no attenuation calibration adjustment. You can determine the actual probe and CRO sensitivity if you have a square-wave pulse generator whose peak-to-peak amplitude is accurately known.
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I got the difference now. Thank you so much.
 
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