Oscilloscope

Oscilloscopes are essential instruments for viewing, analyzing, and measuring time-varying electrical signals. Modern digital storage oscilloscopes (DSOs) digitize the input signal using high-speed analog-to-digital converters and display the waveform on a screen. Key specifications include bandwidth (the frequency at which the response drops by 3 dB), sample rate, memory depth, vertical accuracy, timebase accuracy, and trigger capabilities. Oscilloscope bandwidths range from tens of MHz for basic models to tens of GHz for high-performance instruments.

Calibration of oscilloscopes involves verifying the vertical (amplitude) accuracy, horizontal (timebase) accuracy, bandwidth, trigger sensitivity, and probe compensation. Reference standards include calibrated signal generators, frequency counters, and precision attenuators. Vertical calibration checks the accuracy of voltage measurements at various V/div settings and input coupling modes. Timebase calibration verifies the accuracy of time measurements using a reference frequency source. Bandwidth verification confirms the frequency response meets the manufacturer's specification.

In calibration management, oscilloscopes require moderately complex calibration setups. The calibration laboratory needs signal generation equipment with bandwidth and accuracy exceeding the oscilloscope under test. Calibration intervals are typically 12 months. Many modern oscilloscopes include internal calibration routines (self-calibration) that should be run regularly but do not replace traceable external calibration. Probe calibration is equally important — probes have their own bandwidth, compensation, and attenuation accuracy specifications that must be verified.