Follower jammer considerations for frequency hopped spread spectrum

Design considerations to be used to account for follower jamming of frequency hopping (FH) spread spectrum systems are presented. A follower jammer attempts to determine the hop frequency with a “determinator” circuit, and then generates jamming in a range about that frequency. Geometrical considerations show the spatial limit at which follower jamming becomes impossible. The minimum determination time and the probability of correct determination, P_hc, are derived as a function of the intercepted SNR, and the determinator resolution. Both fast hopping (one or more hops per information symbol) and slow hopping are analyzed. The use of follower jammers against hopped FDMA systems is also discussed. A summary design recipe is given. It is concluded that the vulnerability to follower jammers can be reduced to tolerable levels by use of current practical hop rates