How to Troubleshoot a Night Vision Camera Problem
Night vision cameras don't really see in the darkness. They use small light-emitting diodes (LED's) that project light onto the subject. The LED light is out of the spectrum viewable by the human eye. It is invisible to the eye, but is actually light. The cameras illuminate the subject and can capture clear images in total darkness or low-light.
Check the power supply. Many of the devices use a 9V battery and a power adapter. If your camera is using the 9V battery, replace it. If you're using the power supply, check the plug at the wall hasn't been hijacked by someone and the device hasn't been unplugged. The 9V solution may not work for very long. You might only get a few hours use in a totally wireless environment.
Check for interference if you see lines or noise on the screen. Wireless versions of these cameras often operate at 2.4Ghz---the same frequency as older cordless phones. Use elimination to see if other wireless networks are interfering. Turn all cordless phones off, and don't forget the bases too. Change the channel on the camera if it has that capability.
Be sure that you're not at the maximum wireless range. 2.4Ghz is a small radio wave, and it works best in line-of-sight applications, but it can travel through walls. Effectively, the range will be no more than 150' even with no obstructions.
Make sure you have a weather-resistant camera if you're using it outdoors. It should be marked as such and you should see heavyier seals. There shouldn't be any obvious openings. If the camera isn't weatherproof, it may have degraded and need to be replaced. In any case, try to shield the camera from rain because the water droplets can cause spotting.
Clean the lens from time to time if the picture degrades.
Make sure you haven't exceeded the distance to subject (DST.) if the subject isn't clear. The nature of the beast is that the LED light is projected onto the subject, and there's a finite distance the invisible light will travel. Many cameras will only show a six-foot person head-to-toe at a maximum of 2.5m away. You may have to add regular light to get a better result.
Check the camera isn't pointing directly at a light source, like a street lamp. It can cause the camera's sensors to get confused. Try to keep the camera in the shade during daytime and again don't point it into bright objects, like the sun. Use the sun or light source to light your subject instead.