The arrangement of measuring points followed either a straight li

The arrangement of measuring points followed either a straight line or a sinusoidal line with amplitude less than 1.34 m.Figure 1.Arrangement of laser rangefinder and swivel device (horizontal axis) on a basic vehicle for measuring crop parameters.Lenaerts et al. tested two LIDAR-Sensors for predicting crop stand density under lab conditions [29]. The sensors were mounted in 2.85 m height on a combine harvester. In this paper it was concluded that a sufficient measuring distance und a small beam diameter are
Recent technological advances allow a large number of battery-operated, inexpensive wireless networked sensor devices to be embedded in the physical environment. Wireless sensor networks (WSNs), allow device mobility, fast and easy installation and relocation according to needs.

Application fields cover natural habitat monitoring, structure health controlling, environmental pollutants detection, seismic structural damage monitoring, industrial process control and military target tracking, among others [1].A WSN unit typically contains a set of sensors monitoring physical variables. The processed values are transmitted by means of a radio transceiver working in an industrial-scientific-medical (ISM) band. The use of batteries to supply the system energy [1-2] permits some of their main features, such as mobility or system ubiquity. In order to achieve long battery life (months or even years), power consumption must be carefully managed.A sensor unit can comprise smart sensors, with digital output and low power modes, and transducers that provide a raw analogue output.

Interfacing between such sensors and the digital part of the system often requires conditioning electronics [3-4]. An interface circuit consists of an analogue section to improve the sensor output by extending its linear range and reducing cross-sensitivity to other physical variables, and analogue-digital converters (ADC) to digitize the data to be processed by a microcontroller. Programmability allows a more versatile operation for the interface circuit, which can change its behavior according to the requirements. A classical programmable solution is a polynomial compensation [5]. This solution can be affected by mismatches, reducing its performance. Currently we Drug_discovery can see in the literature more sophisticated solutions, as in [6], where an analogue programmable circuit is presented to amplify the signal supplied by a sensor, compensating the output offset.

In this case, the system merely fits the output signal span to the input range of the ADC available in the microcontroller, but the sensor non-linearities are not corrected. In [7], a versatile conditioning circuit for automotive applications is presented. In this case, the system consists of analogue and digital elements, and power is provided by the car battery, so the adaptation to portable battery operated applications is difficult.

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