Sampling Law

Tech Note

Analog data is stored by modern acquisition systems in digital form. Therefore, analog information must first be transformed to its digital equivalent using an analog-to-digital converter (ADC). In this type of system, the sample rate MUST exceed the highest frequency contained in the “detectable” input signal. This is not an option; it’s the law! In fact, the Nyquist criterion (part of the law) demands that we sample at greater than twice the highest frequency applied to the ADC. This is required to avoid aliasing, which may result in severe errors.

This eNewsletter links you to an application note that explains aliasing, the Nyquist criterion, and the importance of selecting the best sampling rate for your next data acquisition project. This App Note (AN115) also references another excellent document that goes into even more detail.

Dataforth Application Note AN115 - Sampling Law (227kb pdf)

All of Dataforth's signal conditioners include anti-aliasing, low-pass, filters! Bandwidths are set at the factory as "narrow band" or "wide band". That is, the cut-off frequencies are set to provide analog output information for slow-moving signal (3Hz to 4Hz) or for faster-moving signals (3000Hz or 10,000Hz).

Moreover, Dataforth has hundreds of custom signal conditioners that have been designed over the years which could fit your specific application needs. These previously-designed custom products are available in any quantities and can be built and shipped within four weeks, sometimes sooner. New designs are available in low quantities and can be shipped within a few weeks after spec-sheet approval.

Remember, our Application Engineers can assist you with signal conditioner selection over the phone or via fax and email. Call us at our manufacturing facility in Tucson at 520-741-1404 (fax 520-741-0762) or Email us at

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