Locating sound sources

The camera has different filters that help locate interesting sound sources. These filters limit the frequency range that the camera uses to detect sound sources. The filters typically filter out the background noise, allowing the camera to display only the relevant sound sources on the screen.

The camera cycles through user‑defined areas to look for the strongest sound sources within each area and performs its analysis based on that.

The location of the sound source is highlighted using the Acoustic Map in rainbow color. Sound sources that are significantly weaker than the dominant source will not be displayed or analyzed.

The strongest sound source depends on the selected filter, meaning that different sound sources may occur when you use different filters. See section Filters.

The configurator tool connected to the camera displays both the actual sound sources but also any reflections produced by them or by surrounding surfaces.

Reflections may appear in places where you would not expect sound to come from, for example in the center of walls or ceilings. This is more common in enclosed environments where acoustic waves bounce off surrounding surfaces. Also keep in mind that different elements, including electronic or lighting components, which can emit ultrasonic or audible signals that mimic fault‑related noise. To confirm a sound of interest, ensure it aligns with the correct location and originates from a component capable of producing those frequencies.

Reflections often appear with lower dB levels because they result from acoustic waves bouncing off surfaces rather than from the actual emitting source. If the main source has a significantly higher dB level, you can safely disregard the weaker reflections. In PD mode, the camera identifies the true source and displays the PRPD pattern, which you can use to verify that the detected signal corresponds to a genuine partial discharge.

When necessary, use the area‑selection tool to focus the analysis on the components or regions you want to inspect.

Identify the area you want to inspect, as sound sources can be directional and their displayed levels will vary depending on the direction of the incoming waves. Position the camera to capture the phenomenon of interest and point it at specific components or elements that it should capture.

The minimum distance between the sound source and the camera is 0.3 meters. If the distance is shorter than this, the location of sound sources will not be accurately displayed. Additionally, the optical camera will not focus at such short distances.

The autofocus adjusts automatically, make sure the subject is beyond the minimum focus distance of 10 cm for a clear image.

In practice, the camera can be used at distances up to 200 meters. Strong sound sources in quiet environments can be detected from larger distances. However, environmental factors such as temperature, humidity, and background noise may affect distances detection range.

When you set up an alarm, see section Assigning alarms, the configurator tool automatically captures a snapshot of the camera’s view when the alarm conditions are met. You can also manually take a snapshot in the configurator tool by hovering over the selected area and click the capture icon. All saved snapshots appear in the Gallery section, where you can export them by selecting the download option. This generates an NLZ file, which contains the image, a 2–second video, and all associated metadata. The NLZ file is not directly viewable, you must use Flir Thermal Studio to open the file, visualize the image and video, review the signal plots, and generate reports.

The snapshot displays the image and the dB levels captured by the camera at the exact moment the phenomenon occurred.