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An optical preamplifier is utilized to improve the signal-to-noise and distortion ratio (SNDR) of intersatellite microwave photonic links employing a Mach-Zehnder modulator under dual-tone modulation. The resulting SNDR at an appropriate direct current (DC) bias phase shift is additionally investigated without small-signal approximation in order to optimize the performance of all the links. It is observed that the most limiting factor degrading the SNDR performance is changed, and the fundamental power is seen to increase more compared with the power of third-order intermodulation (IM3) plus noise due to the optical preamplifier. Thus, SNDR can be improved with respect to the case of a nonoptical preamplifier. For the preamplifier gain of 20 dB and noise figure of 3 dB, an increase of about 24 dB in optimum SNDR is accessible. In addition, the optimum DC bias phase shift is found to be insensitive to the preamplifier gain and noise figure, while the optimum SNDR is sensitive to the preamplifier gain and noise figure.

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A radar adopts anti-jamming techniques such as side lobe cancellation and moving target indication, resulting in the worsening of the effects of single active jamming and passive jamming. Therefore a compound jamming strategy was proposed and can effectively respond to the anti-jamming device of the new radar. The conditions for the use of this strategy were defined. Based on the military airspace planning principles, taking into account human error, wind and other errors, the specific process of airspace planning was elaborated. Taking into account the effects of compound jamming and the safety of a jammer, an airspace model for stand-off and compound jamming was established. The Whale Optimization Algorithm (WAO) with Tent chaotic sequence was used to solve the model and the airspaces with different preferences were planned. The simulation results show that the model is scientific and effective. The optimization ability of the WOA of with tent chaotic sequence is better than WAO. In addition, the planning direction is quite different in Simulation 1 and Simulation 2, with a maximum of 99°. The compound jamming for stand-off jamming in airspace planning is more flexible and has more advantages in multiple military planning airspaces.

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