Spectral Analysis & Waterfall Charts
For rotating equipment, vibration frequency content often reveals the failure mode more clearly than overall vibration level. Shoplogix IMS includes a waterfall chart that shows how the frequency spectrum of a machine's vibration changes over time — useful for spotting developing bearing faults, imbalance, and misalignment before they become failures.
What the Waterfall Chart Shows
The waterfall chart is a 3D view: frequency (Hz) on the horizontal axis, time on the depth axis, and vibration magnitude on the vertical axis. Each horizontal slice represents one FFT (Fast Fourier Transform) capture from the sensor at a specific point in time.
By reading across time, you can see:
- Frequency peaks that are growing (suggesting a developing fault)
- Peaks that appeared suddenly (suggesting an event like an impact or installation change)
- Stable, periodic peaks (normal running signature for the machine)
Axes and Measurement Types
The chart can display frequency spectra for three axes:
| Axis | Typical Use |
|---|---|
| Axial | Along the shaft — useful for misalignment and thrust bearing faults |
| Radial | Perpendicular to the shaft — useful for imbalance and radial bearing faults |
| Tangential | Third axis — provides additional directional context |
You can switch the magnitude type between:
| Type | Unit | Best For |
|---|---|---|
| Velocity | mm/s | Low-to-mid frequency faults (imbalance, misalignment) |
| Acceleration | mg | High-frequency faults (bearing wear, gear mesh) |
Navigating the Chart
Zoom controls:
- Frequency range — set the min and max Hz to focus on a specific frequency band
- Magnitude range — set the min and max amplitude to scale the Y-axis and reveal smaller peaks hidden under dominant ones
- Reset — returns both axes to auto-scale
3D navigation:
- Drag to rotate the waterfall view and inspect from different angles
- The time depth shows how many FFT captures fall within your selected date range
Time Range Selection
Use the time range controls to select how far back to show data. Common options include the last 7 days, 30 days, or a custom range. Longer ranges give you trend visibility; shorter ranges provide higher resolution for recent events.
When to Use This View
| Situation | What to Look For |
|---|---|
| Machine just entered a Warning or Critical alarm | Check whether a specific frequency peak is driving the high overall vibration |
| Vibration has been elevated for weeks | Look for gradual growth in bearing defect frequencies |
| Machine was recently repaired or realigned | Compare the post-repair spectrum against the pre-repair baseline |
| Trying to confirm a field technician's diagnosis | Frequency peaks can corroborate or challenge suspected failure modes |
Requirements
Spectral data is available for machines equipped with MVM Eversensor 1 or 2. The MHM 1.0 sensor also supports FFT data. See Hardware Reference for sensor capabilities.
Accessing the spectral analysis view requires the Customer User role or above.
Data via API
FFT timeseries data is available programmatically via the REST API:
GET /v2020-07/machines/{id}/timeseries
See the API documentation for available parameters including time range and data type filters.