Microwave photonic technology is a new technology which combines microwave technology and photonic technology. It has great advantages in many aerospace fields such as satellite navigation and space exploration. In the harsh space environment, Fresnel reflection is easy to be produced in the optical connector. In this paper, we build a RF microwave photonic transmission platform to analyse the influences of the optical echo increase and the optical phase change arising from Fresnel reflection of the optical connector on the phase noise. First of all, we present a scheme to simulate the echo of the optical signal caused by the Fresnel reflection. The results show that in our built platform the optical echo caused by the Fresnel reflection can not give rise to phase noise degradation. Secondly, the influence of optical phase change on phase noise by changing the size of air gap is experimentally analysed. As the size rises from 0.3mm to 0.7mm, the phase noise deteriorates to be - 93dBc / Hz at 1kHz.
A new phenomenon of random variation effect on the fiber height in optical fiber connectors is researched. The mechanism of this effect is proposed and analyzed. Based on the theory, this effect is caused by epoxy adhesive that used in fiber connectors under extreme temperature. It is deduced that glass-transition temperature of epoxy adhesive contributes a critical role in this effect. And further investigation is applied to verify this theory. The result demonstrates that the fiber height in optical fiber connector’s contact will be significantly affected if working above the glass-transition temperature of used epoxy adhesive.
Direct detection laser detection and ranging (LADAR) has been widely used in many specific applications such as precision guidance, machine vision, underwater images, landslides investigations, city modeling, and so forth. One of the most promising methods to design, develop, test and validate a LADAR system is hardware-in-the-loop (HWIL) simulation. LADAR target simulator generates return signals of the simulated targets and background according to the test requirements. One of the key technologies of the LADAR target simulator is target modeling. A target modeling method based on data matching and restoring is pdroposed in this paper, which can provide a feasible way for LADAR target simulator to acquire the information of the target. The coordinate transformation is used to transform the target coordinate data under two or more viewpoint coordinate system into the reference point coordinate system to obtain the whole information of the target. Then, the target coordinate data under the reference coordinate system is transformed into a given viewpoint coordinate system. Furthermore, the deley time and the pulse width are calculated arrcording to a return signal mathematical model. Finally, the effects of the incident angle and target distance on target data are analyzed.
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