Rail transit vehicle-mounted emergency alerter for passenger

The invention discloses a rail transit vehicle-mounted emergency alerter for a passenger. The alerter comprises a camera, an emergency press-to-talk button, a POE power supply unit, a low-power microprocessor, a noise detection unit, a speaker and a microphone; the POE power supply unit can supply electricity to a whole alerter main machine; the noise detection unit can detect sound signals in a compartment, convert the detected sound signals and transmit the converted sound signals to the low-power microprocessor, and the broadcasting volume in the compartment where the passenger is located is controlled; the low-power microprocessor can automatically control timing for turning on or turning off the camera and automatically shooting a positive image of the passenger and the process for asking for help according to button trigger information of the emergency press-to-talk button. According to the rail transit vehicle-mounted emergency alerter for the passenger, a special power supply module is not needed, wiring is less, the electrical interface is simple, and equipment is small in size and small in heating. In addition, interference of voices of the passenger and a driver who talk through an intercom to noise detection can be removed, and the anti-interference property is good. Meanwhile, the positive image of the passenger using the alerter can be shot, and post tracking can be facilitated.