DON Mc

The HD-CVI camera format is an analog signal also. It is called Composite Video Interface because it is in fact a Composite of a Sync signal at a higher rate to start the video line, a color burst to synchronize the chroma (color) carrier, a white area just like the analog signal but at a higher rate to fit all the pixels. The Color carrier for the CVI signal is in the 21MHz region as seen on a spectrum analyzer. Both the TVI and CVI signals have a vertical interval also with serrated pulses just like the analog signals of old for vertical blanking. If they were digital signals you would not be able to see any of these things on an oscilloscope. Take a look, you will be surprised. Both the TVI and CVI formats are pure analog High Definition.

Just for the record HD-TVI is NOT a digital signal as transmitted on a cable. It has a Sync pulse, back porch with color burst, White area and chroma information just like the analog video of old. The big difference is the Sync rate is more than doubled to handle the higher picture pixels, and most important the chroma carrier and information is set at a much higher frequency around 29MHz in the spectrum. HD-CVI is also an analog signal, not digital on the cable and both are designed to use 75 Ohm cable. Take a look at the signal on an oscilloscope and you will see what I mean.

If you make your own panel, make sure you use a non-conducting panel material, or insulated through hole BNC connectors to avoid common grounding all the video signals together. Keep them ground isolated from ground and each other or else you might have a big problem if a ground loop gets into your video, it will be distributed to all video images.

It does look like you have a ground loop. There are several articles on this website that explain the different ways a ground loop gets into your video signal, and how to get rid of them. Go to FMSYSTEMS-INC.com and click on the Publications, Technical Publications, then use the search box using ground loop as a key word. You will get all the information you need about ground loops and how to get rid of them.

I hope the gang boxes are not grounded, ground loops can make trouble. You can also buy a low cost round flat plastic pads used as door knob protectors for walls, they are just large enough to cover the box and they are thin so you can drill holes in them. They come in many colors and are less than 1$ each. Buy them at any hardware store.

If you are having lose BNC connections you may have a poorly terminated connector (attachment to cable). Or you must be careful to purchase 75 Ohm BNC connectors. About 70% of the connectors sold in the USA are 50 Ohm type BNC connectors for radio use. Sold as BNC connectors but what impedance. The 50 Ohm type connectors look just like the 75 Ohm type but they have a center pin that is larger in diameter and when mated with a 75 Ohm connector on a camera or DVR they bend the connector and permanently damage the 75 Ohm connector and makes it intermittent in a short amount of time.

By the number of lines of interference it looks like either RF or Switching power supply interference. Does this system have a UPS uninterruptable power supply in use, or is there one operating near by on the same power mains as the camera with this problem? If so try turning it off and disconnecting it from the power mains. If not is the camera grounded by a DC power supply on the negative side or the BNC cable side? Disconnect the camera from its mount and hang the camera from its cables to find out. Do the lines stay in one place but dance around, that would be a classic UPS interference signature. Or do you live across the street from a high power Radio tower? If this interfering signal exists on your power mains then you can try isolating the power supply, if 12 volts use a battery to test for ground loop by powering the camera from a battery. If hanging the camera from its cables works then mount the camera on an insulator to lift the ground. A UPS interference is usually the cause of this type of multiple lines on the screen. If it is a UPS then try to find a simi-sign wave type of UPS instead of the cheap square-wave type so commonly used.

There is a device that will take PTZ (RS422) control and put it onto a video coax cable and recover to RS422 at the other end for the camera. Both the RS422 and the video both use the coax cable without interference. The unit is called DLT/DLR-1, you can find all the info at: fmsystems-inc.com.