Calibration of sensors in sensor networks

In this paper we present a new approach to calibrate sensors in sensor networks in an uncontrolled environment. The proposed algorithm makes a model ofthe distribution ofthe measured quantity. This model can be used to estimate and correct the bias of the sensor The proposed, centralized calibration algorithm is a macro-calibration algorithm which tries to improve the system response as a whole, instead of optimizing the response of an individual sensor The algorithm decides, based on measurements to apply the calculated corrections or not. Testing shows that the algorithm can be applied on e.g. temperature sensors. Systematic measurement errors can be reduced. A combination of a few accurate (expensive) sensors, and a large amount of less accurate (cheap) sensors, can be used together with the algorithm in real life applications to improve the quality of the measurements

A new wireless underground network system for continuous monitoring of soil water contents

A new stand-alone wireless embedded network system has been developed recently for continuous monitoring of soil water contents at multiple depths. This paper presents information on the technical aspects of the system, including the applied sensor technology, the wireless communication protocols, the gateway station for data collection, and data transfer to an end user Web page for disseminating results to targeted audiences. Results from the first test of the network system are presented and discussed, including lessons learned so far and actions to be undertaken in the near future to improve and enhance the operability of this innovative measurement approach

Industry: Using dynamic WSNs in smart logistics for fruits and pharmacy

In this paper we describe a smart way to apply dynamic wireless sensor networks (WSN) in logistics. Especially in the temperature controlled supply chain (cold chain), perishable goods like fruits and pharmaceuticals greatly benefit from real-time quality monitoring during storage and transport in order to avoid quality degradation and spoilage. In our system, wireless sensor nodes called SmartPoints monitor the environmental conditions and generate alarms when specific events are detected. Additionally, they calculate the remaining shelf life of the perishable goods they travel with. When there is an Internet-connected WSN available during travel, the shelf-life prediction and associated alarms are directly sent to a back-end server. Alternatively they are logged on the SmartPoints and flushed upon arrival, such that the remaining shelf-life and alarms are immediately clear and a full history will be available later. Our dynamic WSN supports a number of protocols that enable support for the dynamic processes in logistic processes. The Ambient middleware supports real-time monitoring and remote maintenance across the Internet via wired and mobile wireless network access technologies. Additionally, the middleware offers easy integration with third-party applications. Ambient Studio utilizes the middleware for remote WSN configuration and monitoring