Some aspects of the present disclosure provide for methods, apparatus, and computer software for low-power synchronization of wireless communication devices. In one example, an asynchronous code division multiple access (CDMA) channel may be utilized for uplink communication. By utilizing asynchronous CDMA on the uplink, synchronization requirements are relaxed relative to other forms of communication. Accordingly, a synchronization period after coming out of a sleep state can be short, reducing power consumption during re-synchronization. In another example, a low-power companion receiver, rather than the full-power WWAN receiver, may be utilized to acquire a sync signal while the device is in its sleep state. Once synchronism is achieved via the low-power companion receiver, the full-power radio may power up and perform communication with the network. By shifting the synchronization from the full-power radio to the low-power companion radio, power consumption during re-synchronization can be achieved.

A hydrant apparatus may be employed to monitor a water distribution system, and may include a sensor, a processor, and a local clock source. The apparatus may wake from a low power mode to a sensing mode, receive the sensor data, associate the sensor data with a first local clock time, and return the apparatus to the low power mode from the sensing mode. The apparatus may subsequently wake to an operational mode, determine a second local clock time subsequent to the first local clock time, associate an external clock time with the second local clock time, determine an offset for the received sensor data based on the first local clock time and the association between the second local clock time and the external clock time, and transmit the sensor data and the offset to an external monitoring system.

A communications processor is operative in a plurality of modes including at least a high performance mode, a power savings mode with lower computational capability, and a shutdown mode with a wakeup capability. A memory for the communications processor has a high speed segment and a low speed segment, the high speed segment and low speed segment respectively on a high speed data bus and a low speed data bus, the high speed data bus and low speed data bus coupled by a bidirectional bridge.

A hydrant apparatus may be employed to monitor a water distribution system, and may include a sensor, a processor, and a local clock source. The apparatus may wake from a low power mode to a sensing mode, receive the sensor data, associate the sensor data with a first local clock time, and return the apparatus to the low power mode from the sensing mode. The apparatus may subsequently wake to an operational mode, determine a second local clock time subsequent to the first local clock time, associate an external clock time with the second local clock time, determine an offset for the received sensor data based on the first local clock time and the association between the second local clock time and the external clock time, and transmit the sensor data and the offset to an external monitoring system.

Disclosed is a method of operating a low power wireless receiver in which a radio is periodically operable for receive intervals with sleep intervals therebetween and comprising a sleep clock having a sleep clock accuracy. A first transmission or packet is received. Based on a start moment of the first received packet, and an expected interval between packets, a nominal start moment is determined to start the radio for a packet window until a nominal end moment, for receiving a second packet; the packet window duration is extended in dependence on an estimated drift based on the SCA to provide a widened window. A start moment of a second received packet is measured within the widened window. An actual drift is calculated, from the start moment of the second packet; and an actual start moment and an actual window duration is determined, for receiving a third packet, based on the actual drift.

A communications processor is operative in a plurality of modes including at least a high performance mode, a power savings mode with lower computational capability, and a shutdown mode with a wakeup capability. A memory for the communications processor has a high speed segment and a low speed segment, the high speed segment and low speed segment respectively on a high speed data bus and a low speed data bus, the high speed data bus and low speed data bus coupled by a bidirectional bridge.

A circuit system comprises a processor, a first clock with a first frequency, a second clock with a second frequency, such second frequency being higher than said first frequency and a clock calibration module. The clock calibration module comprises a plurality of counters configured to count cycles of the second clock when triggered. Each of the plurality of counters is configured to be triggered at successive cycles of the first clock. Each of the plurality of counters is configured, after a predetermined number of cycles of the first clock, to output a count of elapsed second clock cycles and the processor is configured to determine, using the counts outputted by the plurality of counters, a ratio between the first frequency and the second frequency.

Disclosed is a method of operating a low power wireless receiver in which a radio is periodically operable for receive intervals with sleep intervals therebetween and comprising a sleep clock having a sleep clock accuracy. A first transmission or packet is received. Based on a start moment of the first received packet, and an expected interval between packets, a nominal start moment is determined to start the radio for a packet window until a nominal end moment, for receiving a second packet; the packet window duration is extended in dependence on an estimated drift based on the SCA to provide a widened window. A start moment of a second received packet is measured within the widened window. An actual drift is calculated, from the start moment of the second packet; and an actual start moment and an actual window duration is determined, for receiving a third packet, based on the actual drift.

A hydrant apparatus may be employed to monitor a water distribution system, and may include a sensor, a processor, and a local clock source. The apparatus may wake from a low power mode to a sensing mode, receive the sensor data, associate the sensor data with a first local clock time, and return the apparatus to the low power mode from the sensing mode. The apparatus may subsequently wake to an operational mode, determine a second local clock time subsequent to the first local clock time, associate an external clock time with the second local clock time, determine an offset for the received sensor data based on the first local clock time and the association between the second local clock time and the external clock time, and transmit the sensor data and the offset to an external monitoring system.

A terminal state indicating method, a terminal state determining method, a base station and a terminal are provided. The terminal state indicating method includes: transmitting a subsequence in a predetermined subsequence set, the predetermined subsequence set includes at least one subsequence, each of the at least one subsequence is configured to indicate that at least two terminals are in a target state, and the target state includes a wake-up state or a sleep state.