Electronic Warfare: And the Infantryman

Infantry Magazine, Sept-Dec, 2000 by Gregory O. Bodge

The education of the infantry soldier generally overlooks the field of electronic warfare. Members of the Military Intelligence and Signal branches have become experts in this field, with only a cursory education on its potential and capabilities being passed on to the Infantry.

With the development of faster, smaller, and more powerful microprocessors and components, the basic elements of electronic warfare have become more powerful and more accessible to more people. Even in the consumer electronics industry, items as basic as cellular and wireless telephones have had to become more sophisticated. They have added digital signal processing and spread spectrum transmissions to prevent eavesdropping and jamming. As the speed of computers increases, the length of time needed to detect a soldier on a radio decreases. Every time an infantryman uses something as basic as a radio without taking specific precautions, he must assume that someone knows where he is and on what frequencies he is transmitting. Therefore, it is vital that any member of the infantry who will use a radio, or any other device designed to transmit electromagnetic waves, know the dangers involved and how to reduce them.

Electronic warfare usually covers three broad areas--electronic sensing (ES), direction finding (DF), and jamming or electronic attack (EA).

Electronic sensing is the ability to determine whether an electromagnetic wave is being transmitted. This is the easiest form of electronic warfare to implement, requiring only an antenna and readily available receivers. The design of a direction-finding system enables a receiver to determine the direction and location of a transmitted signal. DF systems are effective against modern military transmitters, difficult and expensive to create, but rudimentary systems can be built with simple meters and directional antennas. This makes DF less of a threat to infantrymen than ES, but in its fundamental state, it is still an option for many potential enemies. Jamming or EA is the means by which an enemy can prevent the reception of a transmitted signal. It can take on many forms, in a variety of costs and sizes, but generally must be large and expensive, to be effective against modern transmitters.

Electronic sensing devices fall into two categories--signal intelligence and communications intercept. Signal intelligence systems can tell the user if someone is broadcasting, the frequency on which he is broadcasting, and the strength of the broadcast signal. Communications intercept systems allow the user to listen to radio communications. Modern spread spectrum systems and encrypted communications are not easily susceptible to communications intercept systems. This does not mean they are not susceptible to signal intelligence systems. Any transmitted signal, regardless of modulation type, frequency, or content, can be detected if not properly transmitted. With today's processing power, even a short-duration encrypted message can give an enemy valuable information, even though he cannot decipher the message.

Building basic direction finding systems at home is a popular hobby with electronics enthusiasts. These systems generally consist of an antenna, designed to receive in one direction, connected to a power meter. Pointing the antenna at a detected signal indicates the direction of the signal by changes in the power level. The power meter will indicate an increase, and the assumption is that the antenna is pointing at the source. The closer the system gets to the source, the more accurate it is. This one dimensional data will give only an azimuth to the target. Coordinating two or more systems to work a specific signal at the same time can give a location. The more systems that are working the signal, the closer the result will be to the actual transmitter location. Several systems receiving one incorrectly operated platoon radio signal will give the enemy a very accurate fix on the platoon's location, and possibly its movement. This can allow the determination of possible objectives, and even targeting.

Electronic attack systems can deny the enemy the ability to use radios effectively. They can be small, low power, battery operated units, or large, high power, multi-frequency systems. They operate on the theory that a high-power transmitter can distort the transmission of a lower power transmitter on the same frequency. These systems usually transmit noise at a high power and at frequencies known to be in use by enemy forces. A major disadvantage of EA systems is that they are also transmitters and are susceptible to direction finding systems.

Soldiers must take specific precautions to defeat EW systems in the field. With a basic understanding of the way various systems work, common sense can dictate these precautions. A signal cannot be susceptible to listening, jamming, or direction finding without detection. Because of this, the first priority should go to reducing the enemy's detection of the transmitter. Unfortunately, this can also mean making reception more difficult for the intended receiver. One way to overcome this problem is to use the terrain effectively. It is best to place a large terrain feature between the transmitter and the enemy, with no terrain features between the transmitter and the receiver. While this is not always possible, at least a large hill or mountain can be put between the enemy and the transmitter and a small hill between the transmitter and the receiver. Some of the best transmission sites are valleys and draws, which can usually be found in most terrain. If properly positioned, these features will reduce the trans mission strength toward the enemy while allowing transmission to the receiver.