Electronic Intelligence
Also called: ELINT · Topic: Remote Sensing, GIS and GNSS · NCERT: Beyond NCERT
Meaning
Electronic Intelligence (ELINT) is information gathered by picking up and studying electronic signals that are not messages between people. Radar emissions are the main example. A receiver listens for these signals, often from a satellite. It notes how strong each signal is, its frequency (how fast the wave repeats) and where it comes from. This shows where radars and similar systems are and what kind they are. ELINT is one branch of signals intelligence (SIGINT). It is a passive method: the sensor only receives energy and sends out none. Satellites in low Earth orbit can cover wide areas and pass over the same place again and again, which makes ELINT useful for national security and border watch.
Example
EMISAT was India's satellite for measuring the electromagnetic spectrum, which means recording radio and radar signals. It was launched on PSLV-C45 on 1 April 2019 into a sun-synchronous polar orbit about 748 km high. It was a single large satellite. Newer plans instead use many small satellites linked to each other, so that one of them is overhead more often.
Don't confuse with
- Communications intelligence (COMINT): the other main branch of SIGINT. COMINT listens to messages between people, such as voice calls and radio talk. ELINT studies non-message signals such as radar.
- Radar remote sensing: this is active. The satellite sends out its own microwave pulses and records the echoes to make pictures of the ground. ELINT only listens to signals that other systems send out.