DIGITAL INFILL

DIGITAL INFILL

Designed by the SITE Research & Development Division, the Digital Infill system allows the early track opening for travelling trains. Used as part of the national SCMT system (Railway Control System), it helps keep the service regular.
Among its most common applications is one for managing the opening tracks for safe passage of trains following such events as: a delayed activation of a first-category signal; departure from a priority track whose signal is very decentralised compared to normal passenger train stations.

FULLY DIGITAL SYNTHESIS AND CONTROL OF INFILL CODE
HIGH POWER APPLICATIONS FOR VERY LONG TRACKS
• MODULARITY AND VERSATILITY FOR DIFFERENT TYPES OF SYSTEMS

EXCELLENT QUALITY OF GENERATED INFILL CODE (420@178HZ) THANKS TO DIGITAL SYNTHESIS

  • High definition of the waveform
  • High precision and consistent repeatability of all the characteristic parameters of the 420@178Hz code
  • Code synthesis used for increased reliability (innovative feature regarding code application upon completion of the 178Hz sinusoid arcs)
  • Optimisation of power supply, regulated according to the electrical characteristics of the track circuit to be served

HIGH POWER AVAILABILITY AND HIGH EFFICIENCY

  • High available power (about 250 VA) that could be supplied entirely to the given track (possibility of covering long distances)
  • Low power dissipation thanks to high switching amplifier efficiency
  • Optimised consumption thanks to the accurately regulated power supplied to the track circuit

EXTREME MODULARITY DUE TO THE FACT THAT THE SYSTEM WAS DESIGNED FOR THE SINGLE INFILL FUNCTION

  • Ability to implement the exact number of INFILL functions required in each station
  • No dependency constraint between INFILL functions implemented in each station

ERGONOMIC DEVICES THAT CAN BE INSTALLED ON FS (ITALIAN RAIL COMPANY) RELAY BACKPLATES

  • Possibility of installing on 2 or 3-row horizontal relay frames (in the case of a 3-row frame, each of the 3 Infill functions can have its own independent mixer)
  • Possibility of installing on 2 or 3-row vertical relay frames (in the case of a 3-row frame, each of the 3 Infill functions can have its own independent mixer)
  • Possibility of installing in standard 19” rack cabinet, setting the height according to the number of systems to be installed inside.

Reliability, Availability, Maintainability, and Safety (RAMS)

  • SIL 4 system
  • High general readiness of INFILL functions at the station in case of failure of one of the systems
  • Corrective maintenance operations can be applied to individual infill functions

The Infill 420 code is a 178 Hz sinusoidal signal modulated with a square wave at a 420 cpm (7 Hz) frequency; its generation and transmission of track activation are linked to data received from the IS system. Interfacing with coded track circuits requires the use of a mixer, which transmits the INFILL code to the track together with the block codes in the primary band. In systems where no mixer has already been installed, SITE provides a dedicated mixer of its own design.

The DIGITAL INFILL system performs the INFILL function, using synthesis techniques and digital control of the generated signal. The Infill function has a security integrity level rating 4 (SIL 4) and is based on a 2oo2 (two out of two) digital architecture; it inspects the generated signal and, if necessary, intervenes to return the system to a safe state.