【正文】 ol during a real shipment. The experiment was conducted in a refrigerated truck traveling through two countries (Spain and France) which means a journey of 1,051 kilometers. The paper illustrates the great potential of this type of motes, providing information about several parameters such as temperature, relative humidity, door openings and truck stops. Psychrometric charts have also been developed for improving the knowledge about water loss and condensation on the product during shipments. 1. Introduction Perishable food products such as vegetables, fruit, meat or fish require refrigerated transportation. For all these products, Temperature (T) is the most important factor for extending shelf life, being essential to ensure that temperatures along the cold chain are adequate. However, local temperature deviations can be present in almost any transport situation. Reports from the literature indicate gradients of 5 176。C or more, when deviations of only a few degrees can lead to spoiled goods and thousands of Euros in damages. A recent study shows that refrigerated shipments rise above the optimum temperature in 30% of trips from the supplier to the distribution centre, and in 15% of trips from the distribution centre to the stores. Roy et al. analyzed the supply of fresh tomato in Japan and quantified product losses of 5% during transportation and distribution. Thermal variations during transoceanic shipments have also been studied. The results showed that there was a significant temperature variability both spatially across the width of the container as well as temporally along the trip, and that it was out of the specification more than 30% of the time. In those experiments monitoring was achieved by means of the installation of hundreds of wired sensors in a single container, which makes this system architecture mercially unfeasible. Transport is often done by refrigerated road vehicles and containers equipped with embedded cooling systems. In such environments, temperatures rise very quickly if a reefer unit fails. Commercial systems are presently available for monitoring containers and trucks, but they do not give plete information about the cargo, because they typically measure only temperature and at just one point. Apart from temperature, water loss is one of the main causes of deterioration that reduces the marketability of perishable food products. Transpiration is the loss of moisture from living tissues. Most weight loss of stored fruit is caused by this process. Relative humidity (RH), T of the product, T of the surrounding atmosphere, and air velocity all affect the amount of water lost in food modities. Free water or condensation is also a problem as it encourages microbial infection and growth, and it can also reduce the strength of packaging materials. Parties involved need better quality assurance methods to satisfy customer demands and to create a petitive point of difference. Successful transport in food logistics calls for automated and efficient monitoring and control of shipments. The challenge is to ensure a continuous ?cold chain? from producer to consumer in order to guaranty prime condition of goods . The use of wireless sensors in refrigerated vehicles was proposed by Qingshan et al. as a new way of monitoring. Specialized WSN (Wireless Sensor Network) monitoring devices promise to revolutionize the shipping and handling of a wide range of perishable products giving suppliers and distributors continuous and accurate readings throughout the distribution process. In this framework, ZigBee was developed as a very promising WSN protocol due to its low energy consumption and advanced work capabilities. Its potential for monitoring the cold chain has been addressed by several authors but without real experimentation, only theoretical approaches. For this reason, in our work real experimentation with the aim of exploring the limits of this technology was a priority. The main objective of this project is to explore the potential of wireless ZigBee/IEEE motes for their application in mercial refrigerated shipments by road. A secondary objective was to improve the knowledge about the conditions that affect the perishable food products during transportation, through the study of relevant parameters like temperature, relative humidity, light, shocking and psychrometric properties. 2. Materials and Methods . ZigBee Motes Four ZigBee/IEEE motes (transmitters) and one base station (receiver) were used. All of them were manufactured by Crossbow. The motes consist of a microcontroller board (Micaz) together with an independent transducer board (MTS400) attached by means of a 52 pin connector. The Micaz mote hosts an Atmel ATMEGA103/128L CPU running the Tiny Operating System (TinyOS) that enables it to execute programs developed using the nesC language. The Micaz has a ra