A frequency value becomes more meaningful when it is related to machine speed. Order tracking expresses vibration as a multiple of rotational frequency, allowing engineers to compare behaviour even when RPM changes.
The 1X reference
The first order, or 1X, corresponds to one vibration cycle per shaft revolution. Strong 1X activity may be associated with unbalance or other once-per-revolution effects, but diagnosis requires phase, direction, load and structural context.
Higher harmonics and sidebands
Harmonics at 2X, 3X and higher orders can indicate waveform distortion, mechanical looseness, misalignment, rubbing or periodic forcing. Sidebands around a carrier frequency may show modulation caused by load variation, gear defects or speed interaction.
A sensor that exposes multiple harmonic frequencies and amplitudes per axis allows a PLC or SCADA system to trend selected components without transferring the full waveform.
Speed-quality considerations
- Confirm the tachometer or speed estimate is stable before trusting order-normalised results.
- Use the correct shaft speed when gear ratios create multiple rotating speeds within one machine.
- Allow for slip in belt drives and induction motors where mechanical speed differs from the nominal electrical frequency.
- Do not treat a frequency match alone as proof of a specific fault.
Technical basis: PyXis Smart 3-Axis Vibration Sensor datasheet TTN-DS-2026-002, issued 19 July 2026. Confirm the current hardware, firmware and controlled document revision before implementation.
