نتایج جستجو برای: band spectrum

تعداد نتایج: 345716  

2018
Ram M. Narayanan Richard K. Pooler Anthony F. Martone Kyle A. Gallagher Kelly Sherbondy

This paper describes a multichannel super-heterodyne signal analyzer, called the Spectrum Analysis Solution (SAS), which performs multi-purpose spectrum sensing to support spectrally adaptive and cognitive radar applications. The SAS operates from ultrahigh frequency (UHF) to the S-band and features a wideband channel with eight narrowband channels. The wideband channel acts as a monitoring cha...

2013
Mostafa El-Khamy Mohammed Farrag Mohamed El-Sharkawy

Cooperative wide-band spectrum sensing has been considered to enable cognitive radio operation of wireless regional area networks (WRAN) in the UHF and VHF TV broadcasting bands. In this paper, cooperative compressed spectrum sensing is considered to enable fast sensing of the wide-band spectrum. The speed and accuracy of spectrum sensing are improved by further optimization of the compressed s...

2000
Li-Zhi Fang

We present a method of measuring galaxy power spectrum based on the multiresolution analysis of the discrete wavelet transformation (DWT). Besides the technical advantages of the computational feasibility for data sets with large volume and complex geometry, the DWT scale-by-scale decomposition provides a physical insight into the covariance matrix of the cosmic mass field. Since the DWT repres...

2013
Rajwinder Singh Jasvir Singh

In today‘s wireless communication environment, the Radio Frequency spectrum is occupied for different purposes like cellular, Television, military, emergency or satellite communication. The frequency spectrum used for cellular communication is getting over crowded with increasing number of subscribers and demand for high data rate text or video transmission, but the frequency spectrum in other ...

2010
Zaineb Al-Banna

Spectrum utilization is the most recent communications issue which takes great deal of attention from communication researchers where most of the efforts have been dedicated for spectral efficient utilization. Spectrum sharing is one of the solutions considered in the problem of lack of available frequency for new communication services which are unlicensed. In this work we propose an optimal m...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شاهد - دانشکده مهندسی برق و الکترونیک 1392

حلقه های قفل شده فاز تمام دیجیتال یکی از مباحث مهم در دنیای امروز الکترونیک هستند. حلقه قفل فازهای (pll ) که به وسیله روشهای آنالوگ طراحی می شدند نسبت به تغییرات دما و ولتاژ و پروسس حساس بودند. این امر موجب سختی طراحی و نیازمندی به طراحی مجدد در تکنولوژی های جدید می شود. این در حالی است که با استفاده از حلقه های قفل فاز تمام دیجیتال این مشکلات برطرف میشوند. حلقه های قفل فاز تمام دیجیتال (adpll...

2014
Goutam Ghosh Prasun Das Subhajit Chatterjee

The increasing demand of wireless applications has put a lot of limitations on the use of available radio spectrum is limited and precious resource. Many survey of spectrum utilization shows that entire spectrum is not used at all the times, so many of the radio spectrum is underutilized. Some of the frequency bands in the spectrum are unoccupied, some of the frequency bands less occupied and f...

M. Farahmandjou M. Ramazani T.P. Firoozabadi

Nano-sized titanium dioxide TiO2 powder was prepared by new wet chemical route from its precursor Titanium (IV) chloride (TiCl4) as precursor with isopropoxy alcohol in presence of nitric acid under ambient condition. Their morphologies, phase compositions and components of the TiO2 nanoparticles were characterized by transmission electron ...

Journal: :Proceedings of the Imperial Academy 1931

Journal: :The Astrophysical Journal 2018

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