The GPS is a network of 24 satellites equipped with atomic clocks and equally accurate position measuring telemetry gear. Combining GPS with mapping (GIS) and AVL offers many benefits for public safety. In a car wreck, for example, such a system could automatically notify the dispatcher of a possibly injured officer in a specific location. If an officer engages in a high-speed chase, such a system would provide the vehicle's location automatically. If an officer is injured in an encounter with a suspect, help can be sent immediately. Small handheld GPS devices and a wireless modem fitted with a GPS option are the two types of GPS systems currently available. These devices remain continuously connected to a generic street map. Law enforcement GPS provides two-way communications that serve two functions. The system tells the officer where he/she is on a map, and its AVL feature lets the dispatch center know the officer's location. Generally, GPS is used to track fleets for routing purposes and for rolling emergencies. It can also be used to track the route over time and to monitor the vehicle's speed. A hands-free wearable GPS that fits in a backpack is already in the works with a major GPS manufacturer.