Discuss Performance of Corner-Cube Prism for Modulating Retro-Reflector Terminal in Free-Space Laser Communication
Modulating Retro-reflector terminal does not need capture, tracking, targeting(ATP) sub-system .The key unit of this type structure is corner- cube prism,its performance will cause the light beam intensity distribution and light beam divergence angle .There are several factors ,such as effective area , right-angle accuracy, surface-type errors .Those errors caused loss of light power result in communication fail,so in this paper we made a precise analysis as a supplement.
Optical communications development for spacecraft applications
Free-space optical communications systems for deep space and near-terrestrial space environments are now poised for deployment aboard spacecraft. Although many fundamental technical problems have been solved, detailed engineering development is still needed to make space-worthy optical communications terminals. Very high bandwidths (10 Gbps or higher) and fine (1-to 10-μrad accuracy) pointing systems are needed for near-terrestrlal space. For deep space applications, optical links at competitive bandwidths relative to RF systems (e.g., 30 Mbps) with very fine pointing accuracies (<1 μrad) are planned. Deep space applications also require very sensitive receivers and large ground receiving apertures, while minimizing mass and prime power penalties for the added capability, especially for smaller spacecraft. Recent efforts at APL focusing on these issues are summarized in this article.
Third order nonlinear distortion of SAW duplexers in UMTS system
Nonlinearity distortion characterization and accurate modeling techniques for leaky surface acoustic wave (LSAW) devices have been desired in the recently years due to the applications of the Radio Frequency (RF) SAW duplexers in the third-generation (3G) telecommunication system, such as Universal Mobile Telecommunications System (UMTS). In the work, we first discuss the approaches to measure and characterize the 3rd order harmonic generation of the resonators on lithium tantalate YXl42° wafer and YXl48° wafer, with resonance frequency of 800MHz to 900 MHz; Second, we present an effective nonlinear Butterworth-van-Dyke (BVD) model to simulate the multi-tone 3rd order intermodulation effects of a band 5 duplexer; simulation result vs. measurement of 3rd order harmonic generation, 3rd order intermodulation (IMD3) and triple beat are presented.