LS 90


LS is a cab signalling and a train protection system used on the main lines of the Czech and Slovak railways. This system continuously transmits and shows a signal aspect of the next main signal in driver's cabin and when the driver's activity is needed, it periodically checks the driver's vigilance. This is the main function of on-board part of the LS-system.
Trackside part of the LS-system is based on coded track circuits using carrier frequency 75 Hz with 100% amplitude modulation. The signal aspect of the next signal is coded in modulation frequency.
The LS-system can transmit these signal aspects:
The trackside part of the LS-system became an integral part of every Automatic Block used on the lines in the Czech Republic and in Slovakia. Almost the entire fleet of locomotives is equipped with the on-board part of the LS-system.

Mirel VZ1

The on-board device Mirel VZ1, unlike older devices, generates a braking curve according to a received restrictive signal. Nevertheless, the trackside part of the LS-system offers too little information to generate a usable braking curve. Thus, this braking curve is so restrictive that its use is questionable. The driver has two choices then. He has to regulate the speed so that it is lower than the generated speed, otherwise emergency braking is applied; or he can use manual mode and there is no braking curve. However, the Mirel VZ1 has an optional ability to decode the Hungarian signals of the EVM 120. Therefore, the newest Škoda locomotive 380/381 were equipped with Mirel VZ1 instead of LS90 board unit.