Equivalent-Time Sampling

Most Digital Storage Oscilloscopes (DSOs), including Pico PC oscilloscopes, feature Equivalent-Time Sampling (ETS). ETS allows a digital oscilloscope to capture high-frequency signals with a much higher effective sampling rate.

Equivalent-Time Sampling works by constructing a picture of the input signal by accumulating the samples over many wave cycles. Because ETS samples the waveform over a number of cycles it can only be used to measure signals that are repetitive. ETS cannot be used for single-shot or non-repetitive signals.

Figure 1 below shows a 25 MHz sine wave that was captured using a Pico handheld oscilloscope, using a real-time sampling rate of 100 MS/s. Figure 2 shows the same 25 MHz sine wave sampled using digital ETS. From these waveforms you can see that the real-time sampling gives a wave shape so distorted as to be nearly useless, while ETS gives a much more accurate representation of the input signal.

On repetitive waveforms, a Pico oscilloscope with equivalent-time sampling can provide the same accuracy as higher-cost oscilloscopes that have higher real-time sampling rates.

real time sampling

Figure 1:  25 MHz sine wave sampled using real-time sampling


equivalent time sampling

Figure 2:  25 MHz sine wave sampled using Equivalent Time Sampling

ETS is available for:

  • PicoScope 2000 Series
  • PicoScope 3200 Range
  • PicoScope 5000 Series

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