vacuumtube

If a posted firmware comes with a md5 or SHA checksum, then it'd be a lot easier to verify the integrity of the file.

you might wanna talk to your dealer for an upgrade.

MTBF（Mean time between failures) might be very important when choosing HDD. I prefer Seagate, but WD is cheap, Samsung is good, Hitachi is fast. it's up to you.

I would say AVD744 4CH H.264 IVS DVR http://www.cpcamcctv.com/En/Prod_Overview.aspx?prod_id=P101008060

please find the following on page 6 of your user manual: 1. If the HDD is not installed correctly or not installed, the “NO HDD!”, “HDD KEY UNLOCK!”, “UNKNOWN FILE SYSTEM! PLEASE FORMAT IT!” messages will appear for 3 seconds, and then return to 4 CH Multiplexer display mode. *** “UNKNOWN FILE SYSTEM!”: The format of HDD is not accepted by the DVR system. The system only accepts EXT3 format. Users can format HDD by selecting “HDD FORMAT” on SYSTEM menu.

If you would like to physically wipe your hard drive, use Zero Fill, your HDD manufacturer might have it on their website.

Page 22 of your user manual. Please find: *) LS (Level of Sensitivity) “LS” is to set the sensitivity of comparing two different images. The smaller the value is, the higher sensitivity for motion detection. The highest sensitivity setting is 00, and the lowest sensitivity setting is 15. The default value is 07. *) SS (Spatial Sensitivity) “SS” is to set the sensitivity for detecting the size of one object (the number of the grids) on the screen. The smaller the value is, the higher sensitivity for motion detection. The highest sensitivity setting is 00, and the lowest sensitivity setting is 15. The default setting is 03. Note: The default setting of SS is 03, which means once an object is detected more than 3 grids, the system will get triggered. So the value of SS must be less than the number of grids that you set up for the motion detection area. *) TS (Time of Sensitivity) “TS” is to set the sensitivity regarding how long one object stays in the detection area and triggers the recording. The smaller the value is, the higher sensitivity for motion detection. The highest sensitivity setting is 00, and the lowest sensitivity setting is 15. The default setting is 02. *) RE (Reference) “RE” is to set a reference for detection. The default value is 10, which means the DVR will compare the 1st image and the 10th image according to the sensitivity of LS, SS, TS simultaneously. The bigger the value is, the higher sensitivity for motion detection. The highest sensitivity is 61. *) ALARM Select N.C. (Normally Closed) / N.O. (Normally open) / OFF for the alarm polarity. The default alarm value is OFF.