Using an external motions sensor will give you a much better result in your alarm recordings. All Software based motion detection is prone to false alerts due to changes in lighting or general wheather conditions, like rain, snow or fog. Surveillance Solutions, as offered by, e.g., QNAP or Synology, provide a superior software based motion detection. But they still can´t match the accuracy of a hardware sensor, operating in unison with your surveillance camera. Those systems, therefore, offer the option to use the external sensor as the alarm trigger - instead of relying on their internal detection.
Check to trigger an alarm when the alarm inside your camera is triggered. Use the first option if you want to couple the internal motion detection of your camera with the external sensor. Or check the second line to leave the triggering to the external motion detector.
After adding your camera to the QNAP Surveillance Station, just go to Event Management and check the needed option. If you deactivated the internal motion detection of your camera and solely rely on the external motion detector, choose the second check box and let the Surveillance Station monitor the state of your camera´s alarm input. Whenever some trips the detection of your motion sensor, an alarm recording will be triggered on your QNAP NAS.
The first option, on the other hand, monitors the internal alarm state of your INSTAR camera and triggers an alert whenever your camera does. Use this option, if you coupled the internal motion detection of your camera with external sensor! This way the Surveillance Station will only start recording, if both your IN-Motion Sensor and the software based detection of your camera is triggered. This mode will significantly reduce false alerts!