Oscilloscopes display and measure electronic signals including voltage, time, frequency, and waveform characteristics. Calibration verifies the vertical (voltage) and horizontal (time base) accuracy, as well as trigger and bandwidth performance. Modern digital oscilloscopes may also require verification of sampling rate and memory depth effects.
Power on the oscilloscope and allow it to warm up per the manufacturer's recommendation (typically 30 minutes). Run the internal self-calibration routine if available. Record the firmware version.
Apply a known DC voltage to each channel at multiple volts/div settings. Test at three voltage levels per range (10%, 50%, 90% of screen). Record the oscilloscope's measurement and calculate the error relative to the reference voltage.
Apply a known frequency reference signal and measure the period using cursors or automatic measurement. Test at multiple time/div settings. Calculate the time base error at each setting.
Apply a known-amplitude sine wave and sweep the frequency from low to the rated bandwidth. Record the displayed amplitude at each frequency. The -3 dB point (70.7% of low-frequency amplitude) defines the bandwidth.
Verify the trigger functions correctly at each channel on various signal types (sine, square, pulse). Test the trigger level accuracy by comparing the displayed trigger point to the applied signal amplitude.
Record all measurements, reference standard IDs, and calculated errors. Issue the calibration certificate with measurement uncertainty for voltage, time, and frequency. Apply the calibration label.
Vertical accuracy is typically ±3% of full scale (DC accuracy) per manufacturer specification. Time base accuracy is typically ±25 ppm or better for crystal-based oscilloscopes. Bandwidth must meet the rated -3 dB frequency specification.
12 months
Yes, each channel has its own input amplifier and signal path, so each must be calibrated independently. Channel-to-channel skew should also be measured for applications involving multi-channel timing analysis.
Oscilloscope probes have their own compensation and accuracy specifications. Calibrate the oscilloscope first, then verify probe compensation using the oscilloscope's built-in calibration signal. For precise measurements, the probe and oscilloscope should be calibrated as a system.
You need a calibrated voltage source (DC and AC), a frequency reference (crystal or GPS-locked), and optionally a fast pulse generator for bandwidth/rise time verification. Multifunction instrument calibrators like the Fluke 5500A can provide most of these signals.
CalibrationOS tracks due dates, stores certificates, and generates audit-ready reports.
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