TABLE OF CONTENTS The characteristics of the mobile-radio environment have been described in the preceding chapters, including the phenomena of multipath fading, frequency-selective fading, and the various other transmission losses. In this complex medium, the degradation in performance from unintentional interferences can be calculated. In this chapter, the effect on performance of intentional sources of interference, called "jammers," is discussed in terms of its impact on military mobile communications. The various types of jammers can be classified as follows:
Air jammer-The jamming signal can arrive via true line-of-sight propagation and does not experience any fades, while the reception of the desired signal experiences fading. In this case, the necessary jammer transmitting power is relatively weak.
Ground jammer-Both the jamming signal and the desired signal experience fading at the receiving end. In this case, the jammer power can be very high.
Jammers can be classified as (1) CW jammers operating continuously on one frequency; (2) pulsed jammers consisting of on-off jamming utilizing peak power; (3) wideband pseudo-noise jammers operating at a certain bandwidth; (4) partial-band jammers, which utilize the power of the jamming transmitter to efficiently jam a part of the desired signal band while leaving part of the information intact; and (5) follow-up jammers, which can be used to detect a transmitted signal waveform and then transmit an appropriate jamming signal that will jam the receiving end.
There are two main categories of electronic counter-countermeasure (ECCM)...
