Battery power conservation in a selective call system

Claim 2

A method as claimed in claim 1, characterised in that said predetermined codeword (PCW) is transmitted in the frame (F1) immediately following the synchronisation codeword (26) transmitted in a first of said N batches.

Claim 3

A method as claimed in claim 1 or 2, characterised in that each frame (F1 to F8) has a duration corresponding to the transmission of at least two receiver identity codes, in that the base station (10) transmits identity codes in an ordered sequence and in that the control section (14) of a receiver in response to determining that an identity code being transmitted follows the transmission of its own identity code in the sequence de-energises its receiving section (16) prior to the expiry of its frame.

Claim 4

A method as claimed in claim 1 or 2, characterised in that selective call receivers operating different battery conservation regimes are assigned to respective groups, in that the identity codes of the selective call receivers in each of said groups has a prefix which is unique to that group, and in that the control section (14) of a selective call receiver (P1 to P4) in response to determining that the prefix of an identity code being transmitted does not correspond to its group de-energises its receiving section prior to the expiry of its frame.

Claim 6

A selective call system comprising a base station (10) and a plurality of selective call receivers (P1 to P4), wherein the base station (10) comprises means (14) for formatting signals to be transmitted in accordance with a signal format including a succession of batches, each batch commencing with a synchronisation codeword (26) followed by a predetermined integer number, m, of frames (F1 to F8), each frame having a duration corresponding to the transmission of at least one receiver identity code, and transmitting means (12) for transmitting the signals so formatted, and each receiver (P1 to P4) comprises a receiving section (16) and a control section (18) which includes means (30) for controlling the energisation of the receiving section (16), characterised in that the base station comprises means for inserting a predetermined codeword (PCW) in a preselected one of the m frames, in every 1 in N batches, where N is an integer of at least 2, and in that at least one of the receivers (P1 to P4) is controlled by its control section (18) to energise its receiving section (16) to receive said predetermined codeword (PCW), said control section (18) in response to receiving said predetermined codeword (PCW) de-energising said receiving section (16) for a predetermined period and thereafter re-energising said receiving section (16) for a duration corresponding to at least one frame in at least one predetermined batch of said N batches.

Claim 7

A selective call receiver adapted to receive signals transmitted in accordance with a signal format including a succession of batches (22,24,28), each batch commencing with a synchronisation codeword (26) followed by a predetermined integer number, m, of frames (F1 to F8), each frame having a duration corresponding to the transmission of at least one receiver identity code, the receiver comprising a receiving section (16) and a control section (18), said control section (18) including means (42) for storing a synchronisation codeword (26), the receiver's identity codeword(s) and a predetermined codeword (PCW), characterised in that the control section(18) has timing means(32) for controlling the energisation of the receiving section(16), in that the control section(18) in response to detecting the synchronisation codeword(26) causes the timing means(32) to maintain energisation of the receiving section(16) in order to receive the predetermined codeword(PCW) which is transmitted in a preselected one of the m frames, in every 1 in N batches, where N is an integer of at least 2, said control section(18) in response to detecting the predetermined codeword(PCW), causing the timing means (32) to control the energisation of the receiving section(16) in accordance with a predetermined battery power conservation regime, whereby in response to the control section detecting receipt of said predetermined codeword (PCW), the receiving section is de-energised until the expiry of a first predetermined time period after which it is energised for the duration of a frame (F) and thereafter it is de-energised until the expiry of a second predetermined period whereat the receiving section is energised to receive the synchronisation codeword (26) of the batch containing said predetermined codeword (PCW), the sum of said first and second predetermined periods exceeding the duration of a batch.

Claim 8

A selective call receiver as claimed in claim 7, for use in a system in which receiver identity codes of receivers assigned to the same frame (F) of the same batch are transmitted in an ordered sequence, characterised in that the control section (18) comprises means for determining whether a receiver identity code as received is after its own assigned receiver identity code in the ordered sequence, and in response to determining that it is, the control section de-energises the receiving section prior to the expiry of the frame.

Claim 9

A selective call receiver as claimed in claim 7, for use in a system in which receivers which operate a particular battery conservation regime are assigned receiver identity codes including a prefix unique to those receivers, characterised in that the control section (18) comprises means for determining the presence of said prefix in a received identity code and in response to determining that it is absent, the control section (18) de-energises the receiving section (16) prior to the expiry of the frame.