Typical rescue beacon radios transmit a 5 watt signal for 0.5 second once every 50 seconds. Most of these terminals sold since 1997 include a GPS receiver so they can report precise GPS lat-lon location. Aircraft distress radiobeacons (ELTs) are automatically activated by g-force switches that detect sudden deceleration during a crash, while maritime radiobeacons (EPIRBs) are normally activated by contact with sea water. The "406 MHz" distress radiobeacon band is 100 kHz wide and centered at 406.05 MHz. Individual beacons transmit in assigned 3 kHz channels