This European Telecommunication Standard (ETS) applies to 2@45 GHz Short Range Devices (SRDs) for use in Railway AVI whose protocol is defined by UIC Specifications[1]: - with an Radio Frequency (RF) output connection and specified antenna or with an integral antenna; - for data transmission only; - operating on radio frequencies in the 2@446 ?C 2@454 GHz Industrial@ Scientific and Medical (ISM) band@ with power levels up to 500 Mw eirp as defined in the CEPT Recommendation T/R 60-01E[2]. It covers the minimum characteristics considered necessary in order to make the best use of the available frequencies. It does not necessarily include all the characteristics which may be required by a user@ nor does it necessarily represent the optimum performance achievable. This ETS is based upon CEPT Recommendation T/R 60-01E[2]. It is a specific standard covering various Railway applications where the data transmission of the system will be active only during the presence of the train. This ETS covers fixed installed Interrogators (track units) and transponders (mobile stations). For certain measurements the transponders should be measured together with the whole interrogating system. This ETS includes specifications for methods of measurement for equipment fitted with antenna sockets and/or integral antennae. Additional standards or specifications may be required for equipment such as that intended for connection to the Public Switched Telephone Network (PSTN) or other systems.