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81.
卫星导航接收机抗干扰性能评估方法研究 总被引:2,自引:0,他引:2
卫星导航接收机的抗干扰是导航战研究的一项重要内容。合理的抗干扰性能评估方法是对接收机的抗干扰性能进行正确评估的基础,目前卫星导航接收机还没有建立统一的抗干扰性能评价方法。在吸取GPS系统抗干扰性能评估方法的合理性的基础上,提出一种在接收机输入端对抗干扰性能进行评估的方法,与传统的抗干扰性能评估方法相比,该方法更具有工程实际意义。 相似文献
82.
83.
Field of View Increase for Optical Heterodyne Receivers 总被引:1,自引:0,他引:1
A. Waksberg 《International Journal of Infrared and Millimeter Waves》1999,20(6):1059-1071
The field of view of optical heterodyne systems are usually limited by a simple criterion- namely, that ARR 2, where AR is an effective aperture, R the corresponding field of view and the optical wavelength. This paper will demonstrate that with a simple change of systems geometry and the possible use of array detectors, this severe restriction can be alleviated considerably and, in some cases, eliminated. Both coherent sources and thermal radiation sources are considered. This might suggest that heterodyne systems that were eliminated in the past because of that criterion alone, could turn out to be, not only possible, but even advantageous compared to other techniques. 相似文献
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85.
Yi-Ju Chen 《Microelectronics Journal》2006,37(9):985-992
This paper presents an integrated optical receiver that operates at 1 Gb/s in a standard 0.35 μm digital CMOS technology. The receiver consists of an integrated CMOS photodetector, a transimpedance amplifier (TIA) followed by a post-amplification stage and a dual-loop clock and data recovery (CDR) circuit. At a wavelength of 860 nm, the circuit requires an average light input power of −19.7 dBm to obtain a bit-error rate (BER) of 10−12. The complete receiver consumes a total power of approximately 155 mW from a 3.3-V supply. The core circuit area is 0.85×1.32 mm2. 相似文献
86.
本文提出并实验了一种用与彩色副载波锁相的4f_(sc)作为采样时钟,对电视测试信号进行实时采样和编码,由通用微机对电路进行控制和处理数据的计算机辅助测试系统方案。 相似文献
87.
Multi-user detection allows for the efficient use of bandwidth in Code-Division Multiple-Access (CDMA) channels through mitigation of near-far effects and multiple-access noise limitations. Due to its inherent noise and multipath immunity, CDMA multi-access is being considered as a platform for personal communication systems (PCS). As CDMA based digital communication networks proliferate, the need to determine the presence of a new user and integrate knowledge of this new user into the detection scheme becomes more important. The decorrelating detector is a linear multi-user detector that is asymptotically optimal in terms of near far resistance; however, in the presence of a new unknown user, performance of the decorrelator is severely degraded. Adaptive decorrelators are constructed which adaptively augment an existing conventional decorrelator to demodulate a new active user in addition to existing users. Several likelihood ratio based schemes are employed. Both synchronous and asynchronous communication are investigated.This research was supported by the U.S. Army Research Office under Grant DAAH04-93-G-0219. 相似文献
88.
The performance requirements of a RF receiver for a packet division multiple access technology (PDMA) terminal and the corresponding calculations under the true PDMA signal excitations are presented in the paper. The output signal-to-noise power ratio, the reference receiving sensitivity, the maximum input RF power and the dynamic range, the out-of-channel selectivity and the third-order inter-modulation/cross-modulation characteristics are all analyzed for the PDMA terminal RF receiver in detail. And a feasible indirect method for obtaining the output noise power-spectrum-density of the terminal transmitter by measuring transceiver noise figure is also presented. 相似文献
89.
A. H. F. van Vliet Th. de Graauw S. Lidholm H. van de Stadt 《International Journal of Infrared and Millimeter Waves》1982,3(6):817-823
A heterodyne receiver is described in which an InSb hot electron bolometer is used as a mixer. The local oscillator power is obtained by doubling the frequency of a backward wave oscillator. The receiver operates between 460 and 500 GHz (0.65–0.6 mm). Noise temperatures amount typically to 1000 K. 相似文献
90.
Roehrl MH Heffron GJ Wagner G 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,174(2):325-330
Spin state selective experiments have become very useful tools in solution NMR spectroscopy, particularly in the context of TROSY line narrowing. However, the practical implementation of such pulse sequences is frequently complicated by unexpected instrument behavior. Furthermore, a literal theoretical analysis of sequences published with specific phase settings can fail to rationalize such experiments and can seemingly contradict experimental findings. In this communication, we develop a practical approach to this ostensible paradox. Spin-dynamic design, rationalization, and simulation of NMR pulse sequences, as well as their confident and reliable implementation across current spectrometer hardware platforms, require precise understanding of the underlying nutation axis conventions. While currently often approached empirically, we demonstrate with a simple but general pulse program how to uncover these correspondences a priori in the general case. From this, we deduce a correspondence table between the spin-dynamic phases used in NMR theory and simulation on the one hand and pulse program phases of current commercial spectrometers on the other. As a practical application of these results, we analyze implementations of the original (1)H-(15)N TROSY experiment and illustrate how steady-state magnetization can be predictably, rather than empirically, added to a desired component. We show why and under which circumstances a literal adoption of phases from published sequences can lead to incorrect results. We suggest that pulse sequences should be consistently given with spin-dynamically correct (physical) phases, rather than in spectrometer-specific (software) syntax. 相似文献