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Jiang W.,Key Laboratory of Science and Technology on Space Microwave Technology
Applied Optics | Year: 2012

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. © 2012 Optical Society of America.


Zhu Z.,PLA Air Force Aviation University | Zhu Z.,Key Laboratory of Science and Technology on Space Microwave Technology | Zhao S.,PLA Air Force Aviation University | Li Y.,PLA Air Force Aviation University | Li X.,PLA Air Force Aviation University
IET Optoelectronics | Year: 2014

The performance of optical inter-satellite communications using microwave photonics technologies employing intensity modulation with direct detection (IMDD) and phase modulation (PM) with interferometric detection are investigated and demonstrated with a numerical example. The theoretical model considering the saturated gain and amplifier spontaneous emission noise of optical booster amplifier and optical preamplifier is constructed for both architectures. Furthermore, the authors compare the performance of PM with interferometric detection to optimum biased IMDD in terms of radio frequency (RF) gain, RF noise figure and compression dynamic range (CDR). The numerical results show that the PM with interferometric detection can achieve better RF gain, RF noise figure and CDR than the optimum biased IMDD link as the laser output power is lower than 14.34, 12.45 and 4.2 dBm, respectively. © The Institution of Engineering and Technology.


Ding D.-Z.,Nanjing University of Science and Technology | Shen P.,Nanjing University of Science and Technology | Chen R.-S.,Nanjing University of Science and Technology | Shang S.,Nanjing University of Science and Technology | Fan X.-Y.,Key Laboratory of Science and Technology on Space Microwave Technology
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2012

Aiming at the limitation of the traditional tropical rainfall measuring mission (TRMM) Radar, we focus on the next generation precipitation radar system including the Ka-band measurement. In this paper, the scattering characteristics from complex precipitation particles in the K or Ka-band are analyzed by using the sparse-matrix/canonical grid (SMCG) method. We analyze the electromagnetic scattering characteristics of uniformly and randomly distributed rainfall particles model in the Ka-band. Finally, we give the wide-band scattering properties of rainfall particles with arbitrary shape randomly distributed in a certain region. Numerical results are given to supply theory foundation for the development of the next generation precipitation radar. Copyright © 2012 by Editorial Department of Chinese Journal of Radio Science.


Zhu Z.,PLA Air Force Aviation University | Zhao S.,PLA Air Force Aviation University | Yao Z.,Key Laboratory of Science and Technology on Space Microwave Technology | Li Y.,PLA Air Force Aviation University | And 3 more authors.
IET Optoelectronics | Year: 2013

An exact analytical expression of signal-to-noise ratio (SNR) for inter-satellite microwave photonics links using a lowbiased Mach-Zehnder modulator, and with both an optical booster amplifier and a preamplifier, is derived with the method of Bessel expansion and Graf's addition theorem. It is observed that the most limitative noise is changed from the thermal noise to the signal-amplifier spontaneous emission beating noise that arises from the optical preamplifier, and the signal power is seen to increase more compared with the power of noise because of optical preamplifier. Thus, the SNR of system configurations with both an optical booster amplifier and an optical preamplifier can be improved compared with the SNR of system configurations with only an optical booster amplifier. For the preamplifier gain of 20 dB and noise figure of 3 dB, an increase of about 19.7 dB in optimum SNR is accessible. In addition, the effect of optical booster amplifier and preamplifier parameters on the optimum DC bias phase shift and SNR is also investigated. © The Institution of Engineering and Technology 2013.

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