How to know if someone covered your CCTV camera, and get an alert

Two different problems look alike. A covered camera is still sending video, but the picture is blocked. An offline camera has stopped sending video at all. Recorders usually treat them as two separate alerts, and you should switch on both.

• Covered, sprayed or blacked out: look for video tampering, tamper or occlusion in the event or alarm settings.
• Camera disconnected or switched off: look for video loss, IPC offline or network disconnect.
• Alert route: the recorder's phone app, or software that sends a photo of what the camera now sees.
• Test it: cover a lens for a minute and see whether the alert arrives.

You can often tell from the live view, or from a gap in the recordings. Check these in the app or on the recorder.

• A picture that is black, grey or one solid colour.
• A blurry picture that was sharp yesterday.
• A view that has moved, such as the ceiling or the wall where a road used to be.
• A recording that looks unchanged for hours, or a gap that ends when the camera returns.
• A camera that shows no video, with the recorder marking it as no signal or offline.

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Not every model has these checks, and the menu names change with the firmware, so use these as a guide and check your manual.

• Hikvision. On a recorder, go to System, Event, Normal Event, Video Tampering. Select a camera and tick Enable. Drag on the preview to draw the area. Set the Sensitivity from 0 to 2, which gives three levels, where a higher value makes the alarm trigger more readily. Then set the arming schedule and the linkage actions.
• Dahua. On a recorder's local menu, go to Main Menu, Setting, Event, Video Detect, Tampering. Dahua describes it as alerting you when someone masks the lens, or when the output video turns one colour because of a light change. Sensitivity runs from 1 to 6, with 3 as the default. Newer interfaces use different menus.
• CP Plus. In the gCMOB or iCMOB app, push notifications cover four events: motion detection, video loss, tampering and network disconnect. CP Plus says each push message carries only the device, the camera name and the event type.

For a camera that has stopped sending video, the recorder has a separate alert. On Dahua recorders, look under Event, Alarm for IPC Offline. Dahua says the system can raise an alarm when the front-end camera disconnects from the recorder, and that the alarm can start recording, a snapshot and other actions. The disconnection on first start-up is not counted as offline. On CP Plus, the app's video loss and network disconnect events do the same job.

Whatever the brand, the alert only helps if it reaches a person. Check that notifications are enabled in the app and allowed on the phone.

• A sudden change in light can look like covering. Dahua's own description includes video that turns one colour because of a light change, so switching off a light can trigger it.
• Sensitivity set too low misses a partial cover. Set too high, it alerts on every shadow.
• The alert is text. It says which camera and which event. It does not show what the camera sees.
• Not every model has it. An older recorder may only detect video loss.
• Each brand has its own app, and a camera behind a different recorder needs its own setup.

Software on a computer at your site watches each camera's picture. When a view goes dark or loses its focus and stays that way, it raises an event. A second, larger model checks the event before you are told. You get a photo of what the camera now sees, so you can tell in a few seconds whether it is a covered lens or a power cut.

A camera that stops sending video is reported too, after about ten minutes. Read more on camera tampering detection.

• Look at the photo. Is the lens covered, sprayed or blocked, or has the camera lost power?
• Check the other cameras near it. Tampering is often the first step in a theft.
• Call the site or ask someone nearby to look. Decide whether to call the police.
• Afterwards, move the camera out of reach, add lighting or a cage, and review who has access.

We are software, not a camera brand. Our software installs on a Windows computer at your site in 60 seconds and works with Hikvision and Prama, Dahua, CP Plus, TVT, Uniview, Axis, Hanwha, and any camera, DVR or NVR with RTSP or ONVIF.

• A covered, sprayed, blacked-out or out-of-focus camera is standard on every site. You get a photo of what the camera now sees on Telegram and in the Foreman app.
• A camera that stops sending video is reported after about ten minutes, on Telegram and in the Foreman app.
• Smoke and fire, and people after hours in zones you mark, are standard too, and can arrive on WhatsApp.
• Recordings stay on site. Your recorder keeps recording.
• Free 7-day trial on up to 32 cameras, no card. In India it is ₹400 per camera per month plus GST, four cameras minimum.