DigiOpG2
Digital Video Recorder
Page
48
3040-00052
7.
Appendix
7.1
Sensitivity Setting
Motion Detection and Motion Detection Recording
Motion detection is to quantitatively calculate the movement of objects in a series of video images from camera and to
determine if it is over user-defined threshold (motion sensitivity). In motion detection recording, an image with small
movement will be skipped and not be recorded while an image with big movement will be recorded without skip. If motion
sensitivity is set to a value below 100, then recording mode will be changed into ‘Motion Detection Recording’ to activate this
feature.
Continuous Recording
When motion sensitivity is set to 100, the recording mode is changed from motion detection recording to continuous
recording. In this mode, every motion and camera noise will be saved regardless of the quantity of the motion.
Conversely, the required storage space per hour increases at least 2~3 times, compared with motion detection recording, and
the total recording period is decreased to that extent. Therefore, be cautious with settings for important camera channels so
that no motion is skipped.
Noise Detection
AGC (Auto Gain Control) circuit amplifies the output signal of CCD in dark light when the AGC feature of the camera is
turned on (normally selected as ‘on’). At this time, the thermal noise of CCD is amplified as well, displaying numerous small,
insignificant red and blue spots.
Due to the high frequency nature, such CCD noise decreases the compression efficiency and, consequently, leads to increased
byte size per image. The size is almost 2~3 times bigger than that with high motion image at daytime. Besides, since the
distinction between real motion and noise is practically impossible, motion detection algorithm can save unnecessary images
of no real motion, but noise, resulting in continuous recording. As a result, hard disk will be filled with unnecessary images
with noise.
To decrease such unnecessary fill-up of storage with noisy images at night, noise detection feature is included in the motion
detection feature. It makes it possible to skip the images of no motion but noise.
The lower the motion sensitivity setting is, the higher the efficiency of the noise detection is. In order to set the motion
sensitivity to 90, the use of cameras with high CCD sensitivity is recommended.
