novel approaches to expression and detection of oestrus in dairy cows

which is most important for achieving good signal quality and accurate
positioning. Spikes and error are attributed to poor geometry.
4.2.2 Constellation Development
To overcome problems of accuracy and signal quality arising from poor
geometry of the BUs an optimal network of BUs was installed in permanent
positions to span the area covering 2 pens of approximately 40 cows.
Figure 4.8a) and -b) depict the BU set up; a) showing the 6 BUs around
the barn perimeter and b) the 2 BUs in the roof, essential for the height
component of UWB. Figure 4.8 shows the UWB BU network in their exact,
fixed positions which are the optimal positions for best signal coverage in
the concerned area. These known coordinates are entered into the
computer, and form the basic network in which MUs will then calculate
their position. Figure 4.9 complements Figure 4.8 by showing areas of
better and worse coverage; blue shows where there is good signal through
to red which are areas of poor signal coverage. Accuracy of geometry is
measured by the dilution of precision (DOP) in the horizontal (H) and
vertical (V) dimensions in the HVDOP diagram (Figure 4.9). The dilution of
precision indicates the potential accuracy of positioning observation for the
given BU network; the higher the DOP value the worse the accuracy.
Figure 4.9 shows that coverage was best in the central position, where
there was little interference from the structural components, but signal
quality deteriorates closer to the corners, in positions close to steel doors
and the building infrastructure. However, the overall coverage that the BU
network provided was demonstrated to be of good quality and allowed for
accurate communication and positioning by UWB.
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