nPassive elements: seismic, acoustic, infrared, strain,
salinity, humidity, temperature, etc.
nPassive Arrays: imagers (visible, IR), biochemical
nActive sensors: radar, sonar
–High
energy, in contrast to passive elements
nTechnology trend: use of IC technology for increased
robustness, lower cost, smaller size
–COTS
adequate in many of these domains; work remains to be done in
biochemical