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What is Under-Sampling?

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Expensive, high-resolution vibration sensors were conventionally required to capture the impact vibration caused by bearing damage.

However, the inexpensive, low-resolution "conanair" has captured the same impact vibrations, enabling the diagnosis of bearings.

This technology is called Under-Sampling, which actively uses aliasing noise to handle high-frequency signals even at low sampling frequencies. It is mainly used in wireless communication systems that take high-frequency signals.

When a bearing is damaged, high-frequency impact vibrations are generated, and the bearing can be diagnosed by checking the envelope (change in amplitude) and the interval between the vibrations. This is an established technology with a track record of more than half a century.

Traditionally, expensive vibration sensors have been used to measure high-frequency shock vibration.

It is also believed that inexpensive digital output sensors with low sampling frequencies cannot measure such vibrations or that high-frequency impact vibrations create a large fold-back noise that impedes measurement.

However, using a general-purpose vibration sensor capable of under-sampling, we could confirm the impact vibration intervals necessary for bearing diagnosis. The result is a very inexpensive bearing diagnostic machine.