2.?Background2.1. Communication ProtocolsFor the development of a wireless sensor network, the evaluation of different communication technologies is necessary. Some factors that should be considered are: bandwidth, transmission rate, total range, scalability and power consumption. The IEEE 802.11g standard has a maximum transmission rate of 54 Mbps, a maximum range of 150 m and defines a maximum number of 32 nodes for a local area network (LAN); it requires additional encoding, which results in an increase of the power consumption [26]. Another standard for a personal area network (PAN) is the IEEE 802.15.1 (Bluetooth); this standard has a transmission rate of 1 Mbps, a maximum range of 10 m and allows the integration of a network with a master device and up to seven slave devices that can only communicate with their master [27].

The IEEE 802.15.4 (ZigBee) standard has a transmission rate of 250 kbps and a maximum range of 1,000 m in its most recent versions. This standard works in three different frequency bands and could contain up to 65,536 nodes on a network and has low energy consumption [28]. Table 1 shows a comparative between standards as discussed above.Table 1.Comparative between WiFi, Bluetooth and ZigBee standards.A sensor network for monitoring and failure-detection applications in a manufacturing cell with new generation machine tools requires a large amount of nodes because different variables are usually measured; the I
It is well known that the performances of an imaging system are associated with several parameters, which depend on the kind of sensor that is considered.

In 2D imaging, for example, various standards have been defined for photographic equipment [1] and bi-dimensional scanning systems [2], based on specific targets and on the related procedures for estimating Brefeldin_A different system parameters (e.g., the spatial resolution in terms of lines per millimeter, Dacomitinib the amount of noise, image compression and gamma correction functions etc.). The test charts presented in Figure 1 represent an example of such targets.Figure 1.Standard targets for 2D imaging equipment characterization: (a) ISO12233 target for directly measuring horizontal, vertical and oblique resolution of a digital camera and frequency domain analysis; (b) ISO 16067 target for measuring spatial resolution …