In order to provide users with detection of whether their current location is within the scope of law enforcement, this APP will collect location data, and it will continue to be collected even when the app is closed or not in use. The location information can be used to inform users in advance whether they are within the scope of law enforcement and warn them in advance. In the background execution mode, the APP can also be combined with other navigation software. Does not affect the alert function. As with other speed camera apps, we provide accurate maps and use warning signs as the main reminder instead of the actual camera installation location. According to the type of sign, provide passers-by to warn the police for law enforcement, and provide users with a real-time reporting system to remind other passers-by to pay attention. Fixed built-in warning items include fixed cameras, mobile speed measurement, area speed measurement, technology law enforcement.. .And so on this kind of speed measuring, banning, evidence collecting devices.