ERMES

ERMES (European Radio Messaging System or Enhanced Radio Messaging System[1]) 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.[2]

ERMES failed to develop[3] and its frequency band has been reassigned to different use.[4]

Technical specification[edit]
Transmission parameters Transmission parameters, pager interrogation Pager interrogation
 * ERMES transmits the data at 6250 bit/s.
 * ERMES uses Frequency Shift Keying (4-FSK) modulation.
 * 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.