Paging or other selective call system with battery power conservation

Abstract

Selective call systems such as the CCIR Radiopaging Code No. 1 (or POCSAG) have a signal format of successive data batches, each batch having a synchronization codeword followed by a 8 data frames. Each pager is assigned to a frame in every batch, resulting in a battery power conservation duty cycle of 1:8. The invention enables any number of the pagers to operate in accordance with a preselected longer duty cycle. Every N (N>2) successive batches constitute a superbatch, and a pager is assigned to only one or certain ones of the frames thereof. To provide superbatch synchronization a predetermined codeword (PCW) is transmitted in one frame of one batch, preferably the first, of the entire superbatch. A pager energizes its receiving section to receive the PCW codeword, based thereon synchronizes to the batch and super batch, then de-energizes its receiving section for a predetermined interval T1 until reception of the its assigned frame, after which it de-energizes again for another predetermined interval T2 until the PCW codeword of the next succeeding superbatch is received. If N=16, a battery power conservation duty cycle of 1:128 can be achieved. Since the PCW codeword is only transmitted once in every N batches, it does not significantly effect the standard signal format and so the system is transparent to pagers which are to operate at the conventional 1:8 duty cycle. Also, since the synchronization codewords are not effected, rapid recovery of synchronization is retained following deep fade or loss of the transmitted carrier.