Electronic 4* code transmitter unit

The MÜA120-01 electronic code transmitter – an add-on unit for the MATÜA-01 block code transmitter – generates the 120 km/h track information (the so-called 4* code) in the 75 Hz track circuits of signalling equipment, which is needed to operate EVM-120 train stop equipment.

Since this code is needed only very rarely, even on lines with speeds above 120 km/h, the circuits for generating and monitoring the 4* code were – for economic reasons – not built into the new MATÜA-01 electronic block code transmitters developed for the introduction of higher-speed operation.

The MÜA120-01 has no mains power supply or AC power switch of its own, so it can only be used together with a MATÜA-01 code transmitter.

One unit provides the coded feed for one track, so two units are needed on a double-track line. The format of the 4* code was defined by MÁV essentially when development of the EVM-120 train stop equipment began.

The code transmitter is built into a unit matching the design and dimensions of the D55 single-width rack unit; the cover can be sealed. It plugs in through a fixed 12-pin DS connector strip on the unit and a matching socket strip that is part of the interlocking. The electronics are on one 225 × 110 mm printed circuit board, divided into the power supply, the 4* code transmitter and the 4* code monitoring circuits. Two green LEDs give visual indication of operation.

Advantages

• operates from 24 V DC, with low current consumption
• integrated circuit design
• code transmitter and code follower function
• monitoring relay output

References

10 units in operation in automatic block systems on the high-speed lines of MÁV