Member Discussion

Camera Location Fluorescent Lighting

I understand that fluorescent lighting can cause inteference with the video signal, for an IP system where is the best location for a camera when this lighting is being used above / below a certain distance away


There are a number of possibilities here, from high-voltage EMI, to rapid flickering effects seen in the image.

Preventing EMI in the cable is best avoided by running the data in raceways, trays or with hooks that are separated from high-voltage cables by 8" or more. In the context of most installs, this is not very difficult. Basic steps like not lazily laying cable runs atop light fixtures usually prevent problems.

The 'flickering' problem can be mitigated generally with camera settings. The flickering is caused of the frequency of fluorescent light ballasts vs the shutter speed of the camera. This is not a very common issue, but the 'Flicker Free' setting in many cameras will disrupt the sync very slightly to avoid it.

As Brian says, your main concern with fluorescent lighting will be the flicker... I've seen UTP cables draped across the tops of fluorescent fixtures without causing issues; twisted pair is designed specifically to reject EMI.

I've only ever seen one model of IP camera that had issues with fluorescent lighting, and that was a HIK model re-sold under the 3xLOGIC brand some years ago... with that though, the interference on the picture looked like the EMI was actually getting straight to the camera innards; EMI into the network cable would only cause connection failures, not noisy picture.

I have also heard the above referred to as 'banding' rather than flicker. But the cause/affect is the same. This may not even relate to actual EMI (as Matt mentions), but rather a consequence of the exposure/ballast speed syncing up

As mentioned above changing the shutter speed should help resolve it...but most manufacturers have a 'Anti-Banding' or 'Anti-Flicker' mode that auto-magically fixes it :).

Banding is usually related to the line frequency of the mains the lights are on where some parts of the world use 50 hertz and in the US we use 60 hertz. Not usually a concern but in today's world of OEM Asian cameras you could find a camera with a defult 50 hertz setting that needs to be switched to 60 to eliminate banding.

Obviously the "laying line across ballast" issue is a possible source of interference, but I suspect there's enough sheilding in cables this is less of an issue than other sources of interference like HVAC systems or other industrial equipment. Symptoms would be different than banding--more likely intermittement packet loss most likely showing up in macro-blocking in the image.