Filter and Smoothing

To ensure smooth and accurate measurements, applying filter or smoothing algorithms can be beneficial. To disable the filters, set the values to 0.

Filter

The filters helps reduce sudden jumps in distance measurements, which can be caused by unwanted reflections not coming from the primary target. These jumps typically occur when the sensor's alignment to the main target is momentarily disrupted.

Maximum Distance: Set the maximum distance parameter to a value that represents the largest realistic difference between two consecutive measurements for your application. This ensures that only plausible changes in distance are accepted, while any distance differences exceeding this value will trigger the filter.

Maximum Time: Set the maximum time parameter to define the duration after which a new value should be accepted, even if an unrealistic distance jump occurred.

How the Filter Works:

• Triggering the Filter: The filter is activated when a sudden change between two consecutive measured distance values exceeds the defined maximum distance change.

• Output During Filtering: The sensor will continue to output the previous stable measurement until one of the following conditions is met:

  • Restoring the Original Level: The measured distance change returns to within the previous value ± the maximum distance change. At this point, the sensor will start displaying the new measured value.

  • Maximum Time Reached: If the maximum time limit is reached before the original level is restored, the sensor will start displaying the new measured value.

By setting the parameters for maximum distance and maximum time, you ensure the sensor ignores erratic measurements and provides more stable and accurate readings.

The following figure is a simplified representation of the Target view, where x represents time and y represents the measured distance. The events a, b, and c illustrate jumps in the measurement values and how they are managed by the filter.

The filter is not triggered because the change in distance between two consecutive values does not exceed the max distance parameter.

The filter is triggered because the max distance is exceeded. The filter is then deactivated as the value returns to the original level.

The filter is triggered because the max distance is exceeded. The filter is deactivated because the max time limit is reached, and the value is adjusted to the new measured distance.

Smoothing

Smoothing applies exponential averaging to the measurements, which is useful for stabilizing fluctuating distances to the target. This is particularly helpful in dynamic applications, such as monitoring filling levels.

The averaging time affects the time frame over which the exponential averaging is applied and specifies that 95% of the output distance come from the new distance value.

The larger the averaging time, the slower the sensor adapts to new distance values, resulting in a more smoothed output. This means that sudden changes in distance are less immediately reflected in the measurements, providing a more stable reading at the expense of responsiveness. A shorter averaging time allows the sensor to respond more quickly to changes in distance, reflecting new values more rapidly but with less smoothing, which may result in a more fluctuating measurement.