Electronic Warfare

Electronic warfare probably began the moment that a military commander started to listen in on his enemy’s radio dispatches – or jam them when he found them no longer yielded any useful information. Today, electronics is the mainstay of military communications, radar warning systems, missile guidance, spacecraft and aircraft navigation, command and control, artillery fuzing, etc. Using an electronic means for combating such sophisticated weaponry is the spooky business of electronic warfare.

TRW has been quietly active in the technology of electronic warfare for a number of years. Only recently has the technology formally surfaced with the formation of a laboratory for the research, design, development, production, and integration of electronic warfare systems.

Electronic warfare include passive and active techniques and countermeasures, and – what is even more devious –anti-countermeasures. Detecting and monitoring the enemy’s electronic devices constitutes one of the most basic areas of electronic warfare. By hearing and observing the electronic signatures of enemy communications and other equipment, a great deal can be learned about his forces and his battle plan.

When the enemy emitters (equipment which radiates electromagnetic waves) are located, they can either be destroyed by direct battle action, or they can be neutralized by jamming. Jamming involves turning on a powerful transmitter which can blot out the enemy’s signals or blind his radar observers.

However, there are countermeasures against jamming. One of these, known as “frequency hopping”, involves quickly tuning the radar of communications transmitter to another waveband, thereby eluding the jammer. Jammers, on the other hand, can be broadbanded, allowing them to continue to cover the operations of some frequency hoppers.

Sometimes, the enemy can be fooled into thinking that he is receiving signals from a friendly transmitter - when in fact they are from our own stations. During World War 2, for example, the Germans transmitted a radio navigation beam which their bombers could follow to London despite fog or blackouts. However, the British soon learned how to “bend” the beam and turn the Nazi bombers away from London.

With today’s technology, a military pilot can detect if he is being “painted” by radar. His countermeasure equipment enables him to alter the signal reflected from his aircraft so that the enemy radar will “think” he is several miles from his actual position. This technique is known as “spoofing”.

He may not know it, but the moth frequently employs electronic warfare to elude his arch-enemy, the bat. Bats, of course, navigate and locate their pray by means of a sophisticated echo location system.  They emit pulses of sound and listen for the faint return echoes to tell them the distance and direction of objects. The moth, on the other hand, possesses amazingly sensitive ears, which can hear sounds over a frequency range of 3,000 to 200, 000 cycles per second. A moth thus knows when a bat is “looking” at him. Frequently upon hearing a bat, a moth will close his wings and drop vertically and rapidly into the vegetation where the bat cannot follow. Moths also have passive countermeasures against the bath’s acoustic attack system. The wings of a moth are covered by a soft, fine hair which acts as an acoustical damper, significantly attenuating (or absorbing) the bat’s sonar wave reflections. The range within which the bat can find the moth is thus considerably reduced.

The soft, fine hair on a moth’s wing is one of his passive countermeasures. The hair absorbs part of the bat’s sound waves, thereby reducing the rang at which the bat can detect him.

There are many other examples of special electronic warfare systems used by birds, mammals, fish and insects. Many have jamming systems, navigation systems, radar-like warning systems and even decoys that rival man’s ingenuous systems. The ink injected by the squid, for example, is a cigar shaped blob which immediately coagulates in the water and looks very much like the squid itself. In other words, it is a decoy. As the squid ejects this decoy, he also contacts his chromatophores, making his body colorless and practically invisible. The predators thus attack the decoy.

Unlike the systems used in the animal kingdom, man’s electronic warfare is continually and rapidly changing, with new techniques calling for new countermeasures, and these in turn demanding anti-countermeasures.

(By TRW’s Systems group, 1972)

bat

The bat’s acoustic attack system: Bats emit pulses of sound and listen for the faint return echoes to tell them the distances and direction of objects. Source of the photo: Todayifoundout.com

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