Distributed low-power wireless monitoring
A distributed wireless monitoring system with a cloud server and low-power remote sensors includes data encoding/compression at sensors to reduce power use from transmission and storage, event activated operation/data logging triggered by configurable thresholds, remote configuration via the cloud server of event triggering thresholds and correlation templates, distributed processing capabilities, and sensor clock synchronization from a network time service.
1. A method implemented by a remote data acquisition platform in a distributed wireless monitoring system, the method comprising:
receiving over a wireless internet link from a cloud server a difference threshold for event triggering, a sampling interval, a sensor baseline value, a reporting schedule, sensor calibration information, and current time and date information;
sampling by comparators at the sampling interval a sensor value;
activating a data logger if the comparators sense a differential change in the sensor value exceeding the difference threshold for event triggering;
logging the sensor value together with a timestamp as stored data while the data logger is activated;
deactivating the data logger and entering a sleep mode if the sensor value returns to the sensor baseline;
compression encoding the stored data;
periodically transmitting during wireless reporting sessions the compression encoded stored data over the wireless internet link to the cloud server according to the reporting schedule, and receiving during the wireless reporting sessions adjusted configuration parameters from the cloud server, wherein the adjusted configuration parameters comprise difference thresholds for event triggering, data sampling intervals, sensor baseline values, sensor calibration values, reporting schedule intervals, and comparator threshold trip points;
receiving over the wireless internet link from the cloud server a device control parameter;
sending a control signal to a device actuator based on the received device control parameter.
2. The method of claim 1 wherein transmitting the compression encoded stored data over the wireless internet link to the cloud server comprises transmitting the compression encoded stored data if a predetermined threshold of data has been logged.
3. The method of claim 1 further comprising transmitting to the cloud server over the wireless internet link an alarm if a low battery capacity state is detected, if a sensor value exceeds a predefined threshold, or if a predefined comparator difference is exceeded.
4. The method of claim 1 further comprising deactivating the data logger and entering a sleep mode if communications over the wireless internet link to the cloud server is disrupted and more than three connection attempts fail.
5. The method of claim 1 further comprising dynamically downloading over the wireless internet link from the cloud server application code, executing the application code, and uploading over the wireless internet link to the cloud server results of the executing, wherein the application code is a component of a separable program for distributed processing.
6. The method of claim 1 further comprising performing data analysis of sensor values prior to data being transmitted to the cloud server.
7. The method of claim 1 further comprising performing signal processing of sensor values prior to logging sensor values, wherein the signal processing is selected from the group consisting of performing numerical derivatives, low pass filtering, frequency domain adaptive filtering, and time averaging.
8. The method of claim 1 further comprising simultaneously sampling and logging multiple sensor values representative of multiple distinct physical parameters selected from the group consisting of weather, air quality, water level, water flow, water quality, fluid pressure, vibration, image, electric current, solar irradiance, soil moisture.