Low probability of intercept

LOW Probability of Intercept (LPI) analysis shows the effect of scenario-dependent parameters and detectability-threshold factors in jamming and nonjamming environments. The most significant improvement in LPI performance may be obtained by operating at Extremely High Frequency (EHF) and by maximizing the effective spread-spectrum processing gain and the communicator’s antenna discrimination to the jamming signal, and by minimizing the number of symbols in the message. To illustrate this effect, the LPI performance between an airborne command post and two advanced satellite-communications systems were analyzed in this paper. The two satellite systems analyzed operate at Super High Frequency (SHF) (8/7 GHz) and EHF (44/20 GHz). Although this analysis was made for the airborne command post/satellite scenario, it is directly applicable to other scenarios such as surface ships communicating to airborne relays or submarines communicating to satellites. The basic purpose of an LPI capability fpr a communications system is to prevent the enemy from locating our communications systems, which will decrease the effect of both electronic attack (jamming) and physical attack. In an electronic attack, LPI makes it difficult for the jammer to locate the communications channel; in a physical attack, the effectiveness of antiradiation missiles (ARM’S) may be significantly reduced. Additionally, the effectiveness of intelligence functions, such as electronic support measures (ESM), will be significantly reduced by LPI capability. Critical communications links for command and control (C*) are likely to be supported by either satellite communications or extended line-of-sight (ELOS) relayed communications. These links would be used to support essential information exchanges and would therefore be likely targets for enemy ESM interceptors.