Patented "Under-sampling" Technology: Mechanism and Clear Technical Limits

As explained in the previous article, the importance of preserving "Raw Data" that engineers can verify in predictive maintenance is paramount. However, there is a physical barrier: "raw waveform data has a large volume."

Normally, attempting to acquire and transmit raw waveforms in the high-frequency bands required for precision diagnosis of bearings (roller bearings) results in an enormous data volume. This becomes a fatal challenge for wireless sensors, where communication bandwidth and power efficiency are strictly required.

To solve this challenge and continue saving raw data to cloud or local environments while remaining completely wireless, conanair developed and adopted Patent No. 6951474: "Under-sampling Technology."

A Mechanism that Intentionally Utilizes "Aliasing Noise"

Under-sampling technology is a method of acquiring data at an intentionally low sampling rate, contrary to the standard theory of data acquisition (Nyquist-Shannon sampling theorem).

This creates a significant practical advantage: it allows for the detection of minute impacts from "initial bearing anomalies (scratches, chips, etc.)" occurring in high-frequency bands of 1 kHz or higher without missing them, all while minimizing and lightening the data volume to the extreme.

However, Nakayama Mizunetsu honestly informs field engineers that this technology is "not omnipotent." This is because there are clear disadvantages that are unavoidable due to its principles.

[Important] Clear Disadvantages of Under-sampling (Technical Limits)

In under-sampling, vibrations in the high-frequency band are captured as "aliasing" in a lower frequency band than they actually occur.

If strict frequency analysis for a target machine or absolute value measurement at a research and development level is required, it is necessary to use expensive, wired, specialized measuring instruments.

Why can it be used for field predictive maintenance despite "impossible precision measurement"?

Recognizing the disadvantage that precise high-frequency absolute value measurement is not possible, why does conanair adopt this method for monitoring general rotating machinery?

It is because, when the target is narrowed down to "bearings" in general motors and pumps, high-frequency band vibrations simply do not occur under normal conditions.

The most important thing in field predictive maintenance is not knowing "strictly what the absolute value of the high frequency is," but catching the fact (sign of anomaly) that "vibrations in the high-frequency band, which should not normally occur, have started to occur" as early and reliably as possible.

By specializing completely in this "trend management of anomaly occurrence," conanair clears the disadvantages of under-sampling in operation and makes it possible to continue saving "lightweight raw waveform data"—the engineer's greatest weapon—at a low cost.

30-Day Free Trial & Inquiry

Try Conan Air for free for 30 days. Here is what our users are saying:

• Easy installation for immediate use
• No app required; operate via web browser
• No cloud required for fully automatic measurement
• Affordable, including dedicated software

Try equipment anomaly detection and predictive maintenance for free. Please feel free to contact us.

30-Day Free Trial & Inquiry

Try Conan Air for free for 30 days. Here is what our users are saying:

• Easy installation for immediate use
• No app required; operate via web browser
• No cloud required for fully automatic measurement
• Affordable, including dedicated software

Try equipment anomaly detection and predictive maintenance for free. Please feel free to contact us.

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