DFRobot SEN0521 User Manual page 7

(3) Appropriate configurations of detection distance, sensitivity, and delay time
parameters can eliminate interference from certain objects.
2. Installation of Multiple Modules:
When installing multiple modules together, ensure a distance of at least 1 meter
between them and have them facing the same or opposite direction, avoiding any mutual
irradiation among the modules.
3. Reasonable distance parameter testing
(1) The module's maximum detection distance can reach up to 11 meters, with a default
factory setting of 6 meters. However, excessive detection distances may result in
unwanted target interference in scenarios with low installation height or narrow
spaces due to the effects of secondary and multiple reflections, as well as L-
shaped and right-angle reflections, leading to the detection of unnecessary
targets and affecting normal operation.
(2) In scenarios with low installation height and narrow spaces, such as bathrooms,
toilets, and kitchens, it is recommended to set the detection distance to be
smaller than the installation height and lower the sensitivity accordingly.
4. Optimal sensitivity parameters.
The module can be set to 10 levels of sensitivity ranging from 0 to 9, with 9 being
the highest sensitivity and 0 being the lowest. The default sensitivity upon factory
setting is 7. Lower sensitivity levels require greater movement or breathing
amplitudes and closer proximity in order to be detected. Conversely, higher
sensitivity levels in complex situations where weak and interference signals are
present within a wider range of angles can lead to an increase in false positives. In
scenarios with low installation height and narrow spaces, it is recommended to lower
the sensitivity.
5. Reasonable delay time parameters. There are two parameters for delay time:
(1) The first parameter is confirmation delay. Configuring the optimal parameter value
can greatly reduce false positives. Although a larger value is more reliable, it
will take longer for the module to report the detected target when it actually
appears, and it may trigger only when someone walks underneath it. For scenarios
with low real-time triggering requirements and no motion, this value can be
increased to reduce false positives.
(2) The second parameter is disappearance delay (the time delay after the target
disappears). The larger the configured parameter value, the easier it is to reduce
the missed detection rate caused by accidental target disappearance or natural
electromagnetic interference in the environment. Although a larger value is more
reliable, it will take longer for the module to report that the target has
disappeared after it actually disappears. It is recommended that the target
disappearance confirmation time (delay time) should not be set too short. The
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