The manhole cover is installed on the back of the manhole cover. It measures the current inclination angle of the manhole cover through the acceleration sensor. The alarm condition is triggered when the manhole cover is tilted and the inclination angle is over 10° (configurable). The alarm signal is sent to the monitoring center through wireless transmission.
The device supports setting the regular reporting interval, and alarm angle threshold (default 10°). In the normal condition, the device sends the report message at the regular interval. The status flag in the message can be used to differentiate whether it’s the alarm or normal status. When the device detects that the battery voltage is low, the device reports a low voltage warning message.
The conditions of abnormal movement are: ABS (current angle – initial angle) ＞ alarm angle threshold. When the condition is met, an alarm message is sent.