lesson 3 - jamming effectiveness ( stealth technology )

Receiver processing considerations remain the same for noise jamming as for receiver noie, as long as Bj covers at least the bandwidth B of the radar waveform. For Bj < B, the jamming. Although possibly having grater spectral density, is less effective in defeating detection and may further reduced by adaptive filtering in the receiver. Jamming also differs from thermal noise in its amplitude distribution. If the jamming transmitter is operated in the saturated mode, the noise output does not follow the Rayleigh distribution that characterizes random noise. Although a higher average power may be available from the transmitter in this mode, the resulting jamming has less effect on the receiver than the same random noise power. This variation in jamming effectiveness , I’ll discussed it later. The ERP of the jamming transmitter should be multiplied by a quality factor Bj < 1 to account for the effectiveness of the jammer bandwidth and transmitter actually used. Another factor that may reduce the effective ERP of the jammer is the need for polarization diversity. Jammers assigned to mask targets simultaneously in more than one radar may radiate independent noise component on 2 orthogonal polarizations ( such as horizontal and vertical , or right- and left- hand circular ), or a single component at 45 degree linear polarization. The jamming power is not received by the radar, reducing the jammer patter-propagation factor Fpj ( usually by 3 dB )

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