Wireless systems use radio frequencies that are designated by governments for unlicensed use. For example, in North America frequencies near 49 MHz, 902 MHz or 2.4 GHz are available. While these frequencies are not assigned to powerful television or radio broadcasting transmitters, interference from other wireless devices such as cordless telephones, wireless toys, computer wireless networks, radar, Smart Power Meters and microwave ovens is possible.
When it comes to video monitors, you'll want to make sure that the one you're buying offers night vision and a decent resolution. Most baby monitors with a dedicated viewer sadly have low VGA resolutions, which are much worse than the majority of smartphones you can buy these days. A few have a 720p HD resolution, which is decent. We hope more baby monitors go that route in the future.