Selective call receiver with battery saving features and method therefor

#This invention relates in general to selective call receivers and in particular to a method and apparatus for battery saving in a selective call receiver.

#Selective call receivers known in the art are typically battery powered to allow for portability and convenience. As batteries have a limited energy content, reducing the current consumption of a selective call receiver helps to increase an operating duration of the selective call receiver.

#One method of reducing the current consumption of the selective call receiver is to turn off its receiver circuitry when there are no radio signals intended for it. A substantial savings in current is obtained because the receiver circuitry consumes a large portion of the current supplied to the selective call receiver. Typically, the method skips over portions of a selective call signal and thereby saves current during specific time intervals of inactivity when the receiver circuitry is turned off. One prior art method which skips over the POCSAG synchronization codeword is adopted in U.S. Pat. Nos. 4,663,623 and 4,802,240 assigned.

#FIG. 1 is a signaling diagram of a prior art POCSAG protocol signal.

#FIG. 2 is a block diagram of a selective call receiver in accordance with an embodiment of the present invention.

#FIG. 3 is a flow chart of the operation of the selective call receiver processor of FIG. 2 in accordance with an embodiment of the present invention.

#Referring now to FIG. 1, a signaling diagram according to the British Postal Office Code and Standardization Advisory Group (POCSAG) is shown. In a selective call signal that uses a POCSAG signal format 10, a preamble 102 precedes a plurality of data batches. Each data batch of the plurality of data batches in the POCSAG signal format 10 comprises a synchronization codeword 104 and eight data frames. A data frame 106 further comprises two thirty-two bit data word 108, 110. The preamble 102 and the synchronization codeword 104 allows a selective call receiver to bit synchronize with the selective call signal. Prior to receiving the selective call signal, the selective call receiver typically operates in an asynchronous battery saving mode. As is known in the art for POCSAG signaling, a plurality of assigned data frames from the eight data frames is allocated to the selective call receiver.

#In accordance with a preferred embodiment of the present invention, FIG. 2 shows a block diagram of a selective call receiver 20. The selective call receiver 20 comprises a receiver circuit 202 block coupled to an antenna 204 and a processor 206. The processor 206 further couples to a baud rate detector 210, a preamble detector 212, and a synchronization codeword detector 214. Typically, the processor 206 will access a memory device 208, such as a codeplug, for a plurality of predetermined selective call signal parameters that include a predetermined baud rate used by the selective call receiver for the selective call signal and information identifying the plurality of assigned data frames allocated to the selective call receiver.

#A method 30 for battery saving in the selective call receiver 20 is shown in FIG. 3 in accordance with a preferred embodiment of the present invention. The method begins at step 302 after having earlier identified from a preamble that the selective call signal is intended for the selective call receiver 20. A next step in the method 30 occurs when the processor 206 accesses a codeplug 304 for the plurality of predetermined selective call signal parameters. The selective call receiver 20 then performs a baud rate detection 306 at each of the plurality of assigned data frames in one of the plurality of data batches. The baud rate detection is repeated until all the plurality of assigned data frames in the one of the plurality of data batches is completed. Otherwise, the method 30 loops back at step 310 to continue the baud detection at step 306.