Omnibus telephone circuits - Regulations for construction and equipment

Summary

This leaflet concerns the technical aspects of railway telephony, dealing with omnibus circuits as defined in UIC Leaflet 750, Chapter II, B .

The principles defined in this leaflet are old in conception, but have in most cases remained valid to this day.

The systems have benefited from technological advances and their performance has improved.

Fibre optics and new transmission equipment ensure better-quality service on omnibus circuits.

Point 2 is dedicated to transmission channels (overhead lines, copper cables and fibre optics), frequency band widths, attenuation and connections.

Point 3 is devoted to call systems; those most generally used being centralised call lines (many railways having replaced their decentralised call systems with an automatic telephone network).

This point also deals with the various call modes, the nature of call pulses and different call current sources (generators, receivers and repeaters).

Point 4 covers the classification of telephones according to the method of use and defines the technical and operating conditions.

Points 5 and 6 contain recommendations for the construction of new omnibus circuits and their maintenance.

This leaflet does not consider the possible future replacement of omnibus circuits by radio services furnished by GSM-R.