The STP design consists of an arrangement of inexpensive
lenses and sensors in the form of an array that gives it a spatial
resolution capability that can be exploited to classify intrusions
while rejecting false alarms arising from clutter. Similar approaches
to STP design have been investigated previously. For
example, in [2], the authors arrange PIR sensors at different
heights along a pole to improve detection accuracy of humans.
However, an important consideration for us was to restrict the
size of the developed STP. Closer placement of the sensors
could effect the spatial resolution capability. We resorted to a
simple but effective trick of off-setting the sensors with respect
to optical axis of their associated lenses. This provision offers
the required spatial resolution while ensuring a smaller platform
size [1].