Image bouncing up and down

[trol4o 0]

Hi,

 

We have the following problem:

 

I have two parking lots with 4 cameras total (2 entrances, 2 exits), on a single computer with a capture card based on Conexant BT878A chip. All the cameras are connected via baluns with local power supplies.

 

The problem is that the image is moving slightly - the picture is perfect, there is no ghosting, ground loops, etc, but the image is literally "bouncing" a few pixels up and down every few seconds. The cameras are vandal proof domes installed on the barriers - they are not moving.

 

I've encountered the problem many times before, mainly with Geovision cards, but it never bothered me until now.

 

On these parking lots, though, it is critical, because I'm using the cameras for Licence Plate Recognition - we have developed our own parking solution complete with licence plate recognition, barrier automation, automatic payment terminals and so on.

 

The software takes a capture of the image every 3 seconds after a trigger is used (inductive loop or button). If the capture is taken during a "bounce", though, the number is recognized incorrectly, the barrier doesn't open the my phones start ringing. If you park a car directly in front of the camera and start the recognition, every 4th or 5th attempt will be wrong because of the bouncing.

[SEANHAWG 1]

That sounds like a power supply issue. voltage drop or amperage loss could be one of the problems

[trol4o 0]

Nah, we're using local power supplies - every camera has 1A power supply (they use around 300-400 mA), we're using UTP for power and signal, and the power line lenght isn't greater than 10 m. on any camera (from power supply to camera). One of the power supplies is even 3A and the camera still bounces.

[trol4o 0]

Problem solved - this appears to be capture configuration problem. You have to choose field for scanning - odd or even, or you get this bouncing if it's set to "any" field.