Identification-node (Fig. 3a). The identification-nodes are based
on the Imote2 mainboard including a battery board and the Imote
Multimedia Sensor board IMB400 (IMB400 website, 2009). Imote2
board is a wireless sensor network device produced by Crossbow
(Imote2 website, 2009) and specifically designed to develop
applications that need reliable wireless connections and high CPU
requirements (for instance, video applications). The Imote2 uses
the Microprocessor Marvell PXA271 XScale at 104 Mhz, which integrates
three chips, the CPU with 256KB SRAM, 32MB SDRAM and
32MB of FLASH memory. Imote2 has aWireless Coprocessor MMX
DSP for accelerating multimedia operations. The radio module is
the same as in the MicaZ mote with an integrated antenna. The
IMB400 incorporates a camera sensor among other components.
The OV7670 image sensor is a low voltage CMOS sensor that provides,
in a small footprint package, the full functionality of a color
image video camera along with an image processor. Some of the
most remarkable camera features are its resolution (maximum
640×480 pixels) and angle of view (90◦). It should be noted that
when the mote does not take a picture, the Imote2 and its PXA271