I have a GVC-800 card(legit) with 4 infrared 480 resolution cameras. 1 run is about 150', another 90, the other 2 about 70'.
The cameras intermittently ALL seem to have one problem or another. Mostly, the screen will go black with raster lines. if I remove the infrared ring around the lens, the camera 'ususally' picture clears up. Another camera periodically gets a green hue phasing in/out. They are all new cameras and this is a new system setup.
I sent the cameras back to the vendor and he claims he set them up overnight and did not see any problems. They are 24 led, Sony chipset cameras that can be mounted in/outdoors . These problems are significant and there CLEARLY is a problem someplace.
I am using siamese cable (18 gu) and have the AC adapters (4 of them, supplied with the cameras) plugged in at the PC.