A portable unit that may be called from a base station through a radio control channel by a succession of terminating call signals that is sent through the control channel from the base station to the portable unit for a first or restricted time duration (T1), selected in consideration of a battery saving period of a battery saving operation carried out in the portable unit. Within the battery saving period, the portable unit is put into transient active and inactive states during a first time interval and a second time interval, respectively. Selection is made so that the first time duration is longer than the second time interval to receive at least one of the terminating call signals within the first time duration in the portable unit. The base station monitors an acknowledgement signal for a second time duration (T2) after the lapse of the first time duration and interrupts the control channel when the acknowledgement signal is not received within the first and the second time durations. In the portable unit, the battery saving operation is released when the presence of the terminating call signals is detected by a squelch circuit.

Method of transmitting terminating call signals within a restricted duration and a base station and a portable unit for use in the same

A radioactive material detection apparatus includes a transmitter, a radiation sensor and a controller. The transmitter is capable of transmitting information in correspondence with a signal. The radiation sensor has a sensor output and is configured to detect radiation over a predetermined period of time. The controller is configured to receive the sensor output from the radiation sensor and to send the signal to the transmitter for transmission.

Method and apparatus for detection of radioactive material

A method and apparatus for providing extended battery saving operation in a conventional selective call signaling protocol, such as the POCSAG signaling protocol includes the transmission of an ordered batch identifier code word in the first frame following a preamble transmission. Upon detection of the ordered batch identifier code word, those selective call receivers capable of extended battery saving operation would supply power to the receiver only during those batches assigned to the receiver group to which the selective call receiver belongs, such as for every second or fourth batch transmission. The method for providing extended battery saving capability is transparent to conventional selective call receivers operating within the system.

Selective call receiver having extended battery saving capability

A communication device 200 capable of operating in a communication system 100 having a control system which generates information signals with redundant information is disclosed. The communication device comprises: a receiver 214 for receiving the information signals; a circuit which can determine the signal quality of the received information signals 234; and a controller 226 which decodes the received information signals, and further compares the signal quality of the information signals with a predetermined value, and decides if the received signal quality is at least equal to the predetermined value in order to only decode a portion of the information signal. Upon the communication device decoding a portion of the information signal, the communication device 200 is placed in a battery saving mode in order to conserve battery life.

Method and apparatus for providing power conservation in a communication system

A paging receiver includes an improved battery saving circuit which reduces battery usage by powering the radio section and the waveform shaping circuitry only during intervals which include address codewords specific to the given receiver group. Power is not supplied during intervals containing synchronization code signals other than during the first such interval directly following the preamble code. Upon detecting a preamble code during said intervals, power is supplied continuously for a time period sufficient to encompass the synchronization code interval.

Paging receiver having battery saving circuit

In a decoder suitable for use in a paging receiver of the type responsive to a transmission which includes a preamble sequence followed by batches each containing a synchronization word followed by a plurality of address and/or message words, the decoder is operative to detect a single synchronization word. Thereafter, the decoder is powered up to search in its specific frame in each batch by means of a clock which has been synchronized with the transmission and which provides the timing for searching in the specific frame of all subsequent batches. The clock may have coarse and fine modes of timing control, the coarse mode being applicable when initial bit synchronization is being attained, and the fine mode being applied subsequently to reduce the risk of the clock drifting out of synchronization.

Alexander P. Lax

Papers

Decoding arrangements for synchronous receivers