ERMES

From Wikipedia, the free encyclopedia
Jump to: navigation, search

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.[1]

ERMES failed to develop[2] and its frequency band has been reassigned to different use.[3]

Technical specification[edit]

Transmission parameters

  • 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.

Pager interrogation

  • 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.

Related websites[edit]

References[edit]