Possible interference from fluorescent lighting MV21

SOLVED
Stirloin
Here to help

Possible interference from fluorescent lighting MV21

Hi,

 

I've recently setup a Meraki MV21 internal security camera and it's working fine except when the overhead fluorescent lighting gets turned on. This causes lines of shading to roll up the frame. I've played around with the camera settings but it doesn't seem to make a great deal of difference. As a temporary fix I've removed the starter from the nearest light so that doesn't come on anymore but not really a practical solution for the long term. I've taken two screenshots from the dashboard and you can see the change in hue between fixed points on the frame, more pronounced on the left hand side. Any suggestions?

 

Thanks

1 ACCEPTED SOLUTION

Compensation for flickering lights based on the local electrical frequency is now available in the latest stable firmware 3.1. Upgrading to this firmware is now possible in Dashboard. The change notes for 3.1 are below:

 

Bug fix
  • Decreased volume of DNS queries.
New feature
  • Camera Frequency. This setting can be used to reduce flicker by synchronizing the camera's shutter speed with the electrical frequency of artificial lighting in the scene.
Other
  • General stability and performance improvements.

View solution in original post

13 REPLIES 13
jdsilva
Kind of a big deal

We saw something similar with some LED pot lights. Tweaking the aperture value (which implicitly changes shutter speed) helped with the problem. 

Thanks, I've gone through the entire aperture range, the interference effect did improve slightly above 60%, above 85% the picure became unuseable as it became too dark. I've dropped the resolution to standard as well which combined with the aperture setting change has made a difference but it's still very noticeable and would probably be a show-stopper for a full building implementation (this is just PoC at the moment)

GeorgeB
Meraki Employee

What country are your MV21s deployed in? The electrical frequency could be a cause of flickering. We will be releasing a feature in the next couple of weeks which allows for the camera to be configured for 50hz or 60hz frequency compensation to eliminate this.

The camera's are based in the UK, do you have a tentative release date for this feature?

It is expected to reach beta availability in the next 2 weeks.

Ok thanks for the update, I'll keep an eye out on the dashboard

MRCUR
Kind of a big deal

We also saw this with an MV21 in the US that is mounted about 1' above a light. Seemed to not be as noticeable after adjusting the focus a bit, but it's still there at times. 

MRCUR | CMNO #12
GeorgeB
Meraki Employee

If the camera determines it needs a high shutter speed to correctly expose the scene, this may cause bands, strobing, or grey bars to appear in the video when placed next to a fluorescent light. This is because unlike incandescent lights, a fluorescent lights pulses at the electrical frequency of your region (50/60Hz). When the shutter speed is synchronized, or closely synchronized with the pulse rate, it can capture the gaps between the pulses which are not visible to the human eye.

 

The way to avoid this is to either locate the camera further away from the fluorescent light source, enable the correct electrical frequency compensation, set a specific shutter speed, or replace the light source with one that does not pulse.

 

Manually fixing the shutter speed can cause other problems, such as too bright an image when lighting conditions change. MV dynamically adjusts the shutter speed to correctly expose the scene and does not offer manual controls for this setting.

Compensation for flickering lights based on the local electrical frequency is now available in the latest stable firmware 3.1. Upgrading to this firmware is now possible in Dashboard. The change notes for 3.1 are below:

 

Bug fix
  • Decreased volume of DNS queries.
New feature
  • Camera Frequency. This setting can be used to reduce flicker by synchronizing the camera's shutter speed with the electrical frequency of artificial lighting in the scene.
Other
  • General stability and performance improvements.

The MV71 and MV21 I have running both picked up the 3.2 firmware version and I can't see the option to set the camera frequency anywhere in the dashboard, was this feature removed in 3.2?

It can be found under "Network-wide > General > Device Configuration" on F/W 3.1 onward.Screen Shot 2017-11-13 at 9.52.48 AM.png

 

Wouldn't have thought to look for it there as I was looking on the individual camera settings. Unfortunately I don't seem to have that option:

meraki_dashboard_net-wide_general.PNGMV21.PNG

I would suggest you contact the support team who can investigate why you are unable to see the option.

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