Radar Waveforms with Variable Pulse Duration Utilizing Partial Complementarity of Barker’s Sequences Set

aleksa zejak

RT-RK Computer based systems, Novi Sad, Serbia, aleksa.zejak@rt-rk.com

slobodan simić

Military academy, Belgrade, Serbia, slobodan.simic@sbb.rs

Abstract: The maximum radar range is determined by total received energy, which demands that (in radar operation) larger pulse duration should be applied. However, longer pulse duration increases the blind zone of the radar. This paper proposes a spread spectrum radar/sonar, based on a waveform with variable pulse duration as a possible solution for overcoming the blind zone problem. This kind of radar signal is justified from the point of range/time sensitivity control. For targets with constant effective reflection surface, positioned at shorter distance from radar, lower reflected energy (shorter pulse) is required. Search for an adequate group of sequences has begun with the binary Barker sequences. If all Barker sequences for the lengths from 3 to 13 were used as a sequence set, the absolute value of maximum side lobes would be equal 1, just as in the case of a single Barker sequence. This property could also be preserved during the cumulative integration. Sequences should be arranged according the sidelobe sign, taking into account that they are not added, but cancelled instead. This may be considered as a new method for maximum sidelobe suppression, since the result of -32.6 dB is much better than in any other sidelobe reduction procedure for a single Barker sequence.