For the most part, the characteristics of collection instruments used are irrelevant to the data. Typical examples of data are reentry vehicle trajectory, beta, and drag history. The signature is used to recognize the phenomena, equipment, or object when their distinctive features are detected. Full exploitation is costly, requires extensive support facilities, and may require near continu-ous coverage and extensive coordination among participants Source locations may be imprecise A3.4. The conflict in Southeast Asia brought about the development and use of this unique intelli-gence source.
Seismic sensors detect or measure seismic disturbances generated by moving vehicles or personnel.
Magnetic sensors detect changes in the ambient magnetic field caused by the movement or presence of metallic objects. Their range is extremely short, but they can be used to cue other, higher resolution sensors and to identify or classify targets. Electromagnetic sensors detect target emitted electromagnetic radiation. Have a nearly instantaneous intelligence capability Cue other sensors A3.4.3. Unattended sea sensors can provide valuable support to tactical air forces conducting sea interdiction and reconnaissance or surveillance operations.