Here are the basics of what you need to know: X-Band is the least common police radar. It is rarely used anymore except in a couple of states, most notably New Jersey and Ohio. Some small towns might also use it on occasion. X-Band IS frequently used by motion sensors, such as those that automatically open the doors at your local supermarket, so in most cases this is what causes X-band false alerts. K-Band probably has the most radar units out there on the road. However, K-Band is also used for some motions sensors too. Treat K-Band alerts with caution, until you have identified the source. Ka-Band radar is the newest band utilized for police radar. Some sources claim that most of the new units sold are Ka. Generally, with the higher end detectors, false alerts on Ka are rare, so every Ka alert should be treated as police radar until you know otherwise.