ERMES (European Radio Messaging System) is a pan-European radio paging system. Radio paging services depend on the allocation and availability of appropriate frequencies in order to transmit and receive between fixed-base stations and radio paging receivers respectively. European Telecommunications Standard Institute (ETSI) has developed the European Telecommunications Standard ETS 300 133 for ERMES operating in the frequency band 169.4125-169.8125 MHz.
- ERMES transmits the data at 6250 bit/s.
- ERMES uses Frequency Shift Keying (4-FSK) modulation.
Transmission parameters, pager interrogation
- Each paging transmission is divided into 60 cycles of 1 minute in length.
- Each cycle is divided into 5 subsequences of 12 seconds.
- Each subsequence is further divided into 16 batches, labeled A through P.
- The pager population is divided into 16 groups.
- Each pager group is allocated to one of the 16 transmission batches [A...P].
- The pager needs only to be active during the period it has been allocated to, allowing it to go into sleep mode 15/16 (~=93%) of the time (a ~7% duty cycle). This scheduling allocation protocol extends the battery life of the pager by several orders of magnitude.
- Council Directive 90/544/EEC of 9 October 1990 on the frequency bands designated for the coordinated introduction of pan-European land-based public radio paging in the Community
- Ofcom's Public Wide Area Paging Information
- Commission Decision of 20 December 2005 on the harmonisation of the 169,4-169,8125 MHz frequency band in the Community