Continuing on from the post Don’t let your being slack set them free, the CCTV system not recording at the time of an incident is the second most common reason we don’t get useable footage.
Check it’s recording every week
You would be amazed how many systems I have been called out to do an audit on where the recordings stopped several months ago.
Assuming nobody reading this is still using a VCR to record, the common cause of recording failure in most CCTV designs is hard drive failure. The risk of this occurring can be significantly reduced by replacing the hard drives every 20,000 hours or at what ever the manufacturer states it’s MTBF at. However this does not eliminate the unexpected failure, which may have been caused by over heating or power jolts due to no UPS being installed.
Checking that the system is recording once a week will dramatically reduce the chances of you having a missed recording due to the DVR / NVR having stopped some time ago.
Ensure you have the required storage time
When you first designed your CCTV system, one of the questions should have been ‘how long do you require to store the footage before deletion?’ Assuming you required 30 days, the system would have been tuned to give you the resolution and frame rate to achieve this on your hard drive capacity. Because most DVR’s and NVR’s record based on a motion based compression such as H.264 or MPEG4, if the scene on one or more cameras changes significantly over time, your storage may reduce.
Common causes of a reduced storage time are:
- An object hanging in the camera’s view such as an advertising display that is being moved by an air conditioner
- A camera that is recording all night with no lights on so the image is filled with speckles of electronic noise
- Interference in the cameras signal
The easy check for this is to search for a date 30 days ago and play it. If it does not not have any recordings, most DVR’s will go to the oldest recording, which may only be a few days back.
If you are not achieving the required time, first check several night time recordings for each camera to see if there is noise from interference or poor lighting. Then look for objects hanging in the scene that could be seen as movement. Lastly, some DVR’s have the ability to remove a faulty hard drive and keep recording on the others so you will need to check the status of your drives.
