Datasheet

SAMPLE RATE

The sample rate of an oscilloscope is similar to the frame rate of a movie

camera. It determines how much waveform detail the scope can capture.

Determine what you need

 Sample rate (samples per second, S/s) is how often an oscilloscope samples the

signal. Again, we recommend a ‘ﬁve times rule’: use a sample rate of at least 5x your

circuit’s highest frequency component.

 Most basic scopes have a (maximum) sample rate of 1 to 2 GS/s. Remember, basic

scopes have bandwidth up to 200 MHz, so scope designers usually build in 5 to 10

times oversampling at maximum bandwidth.

 The faster you sample, the less information you’ll lose and the better the scope will

represent the signal under test. But the faster you will ﬁll up your memory, too, which

limits the time you can capture.

Accurate reconstruction of a signal depends on both the

sample rate and the interpolation method used. Linear

interpolation connects sample points with straight lines, but

this approach is limited to reconstructing straight-edged

signals. Sin(x)/x interpolation uses a sine function to ﬁll in

the time between real samples. It lends itself to curved

and irregular signal shapes, which are far more common

than pure square waves and pulses. Consequently, sin(x)/x

interpolation is the preferred method for most applications.

10 FACTORS IN CHOOSING A BASIC OSCILLOSCOPE

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