EVM (train protection)
EVM is a train control system that is installed on all main lines of the Hungarian State Railways (MÁV).
The trackside part of the system consists of coded track circuits that work with a carrier frequency to transmit information. The carrier frequency is coded by an amplitude modulation of 100% with an electronic coding device. The data transmission between the coded track circuits and the on-board unit takes place via inductively coupled air coil antennas above the rails .
The data transfer from the line to the trains takes place through:
- 75 Hz carrier frequency
- Amplitude modulated codes (100%)
- 7 codes (6 speed codes)
The driver is shown:
- Cab signaling
- Signal position: stop, permissible speed at the next signal (15 km / h, 40 km / h, 80 km / h, 120 km / h, MAX km / h),
- no transmission / failure,
- Maneuvering mode
The following is monitored:
- Speed limit
- Vigilance control every 1,550 m, if v is <v target ,
- Vigilance control every 200 m, if v is > v target
- Stop signal
- Speed limit in maneuvering mode
The emergency brake is triggered
- if the driver does not react
- if the speed limit is exceeded after the alertness signal, or
- if a stop signal is passed at more than 15 km / h
- in maneuvering mode immediately after exceeding 40 km / h (in this case the brake is activated without any acoustic signal)
There are also additional functions:
- Roll-away protection
- Comfort function (display that the signal has moved to the running position when the train is stationary)
With regard to ETCS , EVM is managed as a Class B system (Class B system). A Specific Transmission Module (STM) exists for EVM .