75392 research outputs found
Sort by
The Study on SAR Images Exploitation for Air Platform Navigation Purposes
No full textscore: 10collation: 347-35
LLRF Control System Upgrade at FLASH
No full textabstractEN: The Free Electron Laser in Hamburg (FLASH) [1] is a user facility providing high brilliant laser light for experiments. It is also a unique facility for testing the superconducting accelerator technology for the European XFEL and the International Linear Collider. As a test facility, the accelerator undergoes a constant modification and expansion. The last upgrade was started in autumn 2009 and has finished recently [2]. The beam energy is increased to 1.2 GeV by installing a 7th superconducting accelerating module. The new module is a prototype for the European XFEL. In order to increase the free-electron laser (FEL) radiation intensity by linearization of the beam phase space the 3rd harmonic superconducting RF cavities are installed in the injector. The old DSP based LLRF control system [3] has been completely upgraded to latest generation controller boards, down-converters for higher intermediate frequency, algorithms like beam loading compensation, feed-forward waveform generation, etc. are improved. In order to improve the reference frequency signals the master oscillator and frequency distribution system has been upgraded as well.score: 3collation: 150-15
Analysis of Distortion in SAR Images Generated by Aircraft Mavement Inaccuracy
No full textscore: 1collation: 455-46
Carrierless amplitude phase modulation of VCSEL with 4 bit/s/Hz spectral efficiency for use in WDM-PON
No full textabstractEN: We experimentally demonstrate successful performance ofVCSEL-based WDM link supporting advanced 16-level carrierlessamplitude/phase modulation up to 1.25 Gbps, over 26 km SSMF with spectral efficiency of 4 bit/s/Hz for application in high capacity PONsscore: 45collation: 26551-2655
Preliminary Results of Ground Reflectivity Measurements Using Noise Radar
No full textabstractEN: The paper describes experimental L-band ground reflectivity measurement using noise radar demonstrator working as a scatterometer. The radar ground return is usually described with a scattering coefficient, a quantity that is independent from the scatterometer system. To calculate the coefficient in a function of incidence angle, range profile values obtained after range compression were used. In order to improve dynamic range of the measurement, antenna cross-path interference was removed using lattice filter. The ground return was measured at L band both for HH and VV polarizations of radar wave as well as for HV and VH crosspolarizations using log-periodic antennas placed at a 10 m high mast directed towards a meadow surface. In the paper the theoretical considerations, noise radar setup, measurement campaign and the results are described.score: 10collation: 80081V-1-80081V-
Present Status of Pi of the Sky Telescopes
No full textabstractEN: In October 2010 Pi of the Sky set up a new system, consisting of 4 cameras installed on a new mount, in El Arenosillo, in southern Spain. It was followed by moving the prototype system from Las Campanas Observatory (central Chile) to San Pedro de Atacama (northern Chile) in March 2011. In this paper our new sites, some details about observational conditions and first results in both observatories are described.score: 10collation: 80080Y-1-80080Y-
Extending the Integration Time in DVB-T-based Passive Radar
No full textabstractEN: In the paper a problem of extending integration time in DVB-T-based passive radar is addressed. Inpassive radar, target detection is based on calculating the crossambiguity function between thereference and echo signals. To obtain higher signal-to-noise ratio after the processing, longerintegration time can be used. However, extending the integration time using classical formula forcrossambiguity function leads to signal-to-noise ratio losses. We analyse the simplifying assumptionsused in classical crossambiguity and present more general form of the crossambiguity function, whichallows us to use longer integration times with reduced losses in signal-to-noise ratioscore: 10collation: 190-19
