Characterizing Exoplanets in the Visible and Infrared: A Spectrometer Concept for the EChO Space Mission

Transit-spectroscopy of exoplanets is one of the key observational techniques to characterize the extrasolar planet and its atmosphere. The observational challenges of these measurements require dedicated instrumentation and only the space environment allows an undisturbed access to earth-like atmospheric features such as water or carbon-dioxide. Therefore, several exoplanet-specific space missions are currently being studied. One of them is EChO, the Exoplanet Characterization Observatory, which is part of ESA's Cosmic Vision 2015-2025 program, and which is one of four candidates for the M3 launch slot in 2024. In this paper we present the results of our assessment study of the EChO spectrometer, the only science instrument onboard this spacecraft. The instrument is a multi-channel all-reflective dispersive spectrometer, covering the wavelength range from 400 nm to 16 microns simultaneously with a moderately low spectral resolution. We illustrate how the key technical challenge of the EChO mission - the high photometric stability - influences the choice of spectrometer concept and drives fundamentally the instrument design. First performance evaluations underline the fitness of the elaborated design solution for the needs of the EChO mission.Comment: 20 pages, 8 figures, accepted for publication in the Journal of Astronomical Instrumentatio

The Goldstone solar system radar: A science instrument for planetary research

The Goldstone Solar System Radar (GSSR) station at NASA's Deep Space Communications Complex in California's Mojave Desert is described. A short chronological account of the GSSR's technical development and scientific discoveries is given. This is followed by a basic discussion of how information is derived from the radar echo and how the raw information can be used to increase understanding of the solar system. A moderately detailed description of the radar system is given, and the engineering performance of the radar is discussed. The operating characteristics of the Arcibo Observatory in Puerto Rico are briefly described and compared with those of the GSSR. Planned and in-process improvements to the existing radar, as well as the performance of a hypothetical 128-m diameter antenna radar station, are described. A comprehensive bibliography of referred scientific and engineering articles presenting results that depended on data gathered by the instrument is provided

Control of quantum phenomena: Past, present, and future

Quantum control is concerned with active manipulation of physical and chemical processes on the atomic and molecular scale. This work presents a perspective of progress in the field of control over quantum phenomena, tracing the evolution of theoretical concepts and experimental methods from early developments to the most recent advances. The current experimental successes would be impossible without the development of intense femtosecond laser sources and pulse shapers. The two most critical theoretical insights were (1) realizing that ultrafast atomic and molecular dynamics can be controlled via manipulation of quantum interferences and (2) understanding that optimally shaped ultrafast laser pulses are the most effective means for producing the desired quantum interference patterns in the controlled system. Finally, these theoretical and experimental advances were brought together by the crucial concept of adaptive feedback control, which is a laboratory procedure employing measurement-driven, closed-loop optimization to identify the best shapes of femtosecond laser control pulses for steering quantum dynamics towards the desired objective. Optimization in adaptive feedback control experiments is guided by a learning algorithm, with stochastic methods proving to be especially effective. Adaptive feedback control of quantum phenomena has found numerous applications in many areas of the physical and chemical sciences, and this paper reviews the extensive experiments. Other subjects discussed include quantum optimal control theory, quantum control landscapes, the role of theoretical control designs in experimental realizations, and real-time quantum feedback control. The paper concludes with a prospective of open research directions that are likely to attract significant attention in the future.Comment: Review article, final version (significantly updated), 76 pages, accepted for publication in New J. Phys. (Focus issue: Quantum control

System analysis and integration studies for a 15-micron horizon radiance measurement experiment

Systems analysis and integration studies for 15-micron horizon radiance measurement experimen

Simultaneous Determination Of Modulation Types And Signal-To-Noise Ratios In Wireless Communication Systems

Signal parameters determination techniques can offer more reliability, larger bandwidth, and higher security to the modern wireless systems. However, the performance comparison of such determination techniques is not straightforward. This can be attributed to the lack of having benchmarks datasets in the wireless communication research community as compared to other research fields. Hence, there is a need to propose potentially-benchmark datasets that can be a future choice for researchers in the wireless communication domain, motivating the first contribution in this thesis. Most of the up-to-date solutions of signal parameters determination techniques focus on determining only one single parameter for example modulation type and assuming the other parameters e.g. signal-to-noise ratio (SNR) are known rather than on determining multiple signal parameters jointly. Hence, the desire to enable an autonomous capability of simultaneous determination of multiple signal parameters has motivated the second and third contributions that tackle the non-coherent and coherent receivers, respectively. Therefore, the objectives in this thesis are as follows, firstly, to construct three datasets for the aforesaid receivers to be utilized for joint determination of modulation types and signal-to-noise ratios, namely asynchronous amplitudes histograms (AAHs)-based Dataset, two-dimension alasynchronous sampling in-phase-quadrature histograms (2D-ASIQHs)-based Dataset 1 and 2D-ASIQHs-based Dataset 2. Secondly, to develop a scheme that cansimultaneously determine the modulation type and signal-to-noise ratio in non-coherent receivers by using one features’ type (AAHs-based features) under a multipath fading scenario. Lastly, to develop a scheme that can simultaneously determine the modulation type and signal-to-noise ratio in coherent receivers by employing 2D-ASIQHs features under Rician and Rayleigh fading. For datasets formation, the three datasets are developed under multipath fading channels and used to validate the proposed determination schemes in the second and third contributions. The simultaneous determination AAHs-based scheme enables a generic intelligent receiver to recognize various modulations that belong to different categories and reveals that the recognition capability can be extendable further to other more signal types. The scheme can also simultaneously estimate the SNR values accurately. The simultaneous determination 2D-ASIQHs-based scheme tackles the coherent receivers to jointly determine nine modulation types and a wide range of SNRs. The most significant features are extracted using principal component analysis (PCA) and then fed to a support vector machine (SVM) tool for the automatic learning process. In the simulation results, the samples of the datasets reflect 1D-envelope histograms and in-phase-quadrature-based images which comprise various modulation types and SNRs with different combinations of path gains and delays. In term of modulation recognition accuracy and mean SNR estimation error, the proposed AAHs-based scheme attains 99.83% and 0.79 dB, respectively. Similarly, the proposed 2D-ASIQHs-based scheme achieves 99.06% and 1.10 dB, respectively. The obtained results showed that the proposed schemes outperform the existing state-of-the-art work

A four-beam optical polarimeter for robust particle shape detection

Particle shape detection and measurement are important features in the more general field of particle analysis and characterisation. Knowledge of the particle shape is useful in a wide variety of industrial applications. Although it is often practically feasible to use imaging technologies for particle shape analysis, this is not often a sufficiently efficient method for widespread on-line or in situ applications. In many applications it would be sufficient to have an indicator of particle shape, in the same way that a turbidity sensor is an indicator of the amount of particles present. Scattered polarized light from individual particles will be shown as a useful tool for particle shape detection. In principle, the presence of non-spherical particles can be diagnosed by analysing the change in polarisation state following scattering and in particular exploiting a configuration in which spherical particles produce no such changes. The concerns of this thesis are the design and implementation of optical polarimeters for the detection of non-spheres in an aqueous suspension, with particular emphasis on a robust implementation. [Continues.

Automatic recognition of the digital modulation types using the artificial neural networks

As digital communication technologies continue to grow and evolve, applications for this steady development are also growing. This growth has generated a growing need to look for automated methods for recognizing and classifying the digital modulation type used in the communication system, which has an important effect on many civil and military applications. This paper suggests a recognizing system capable of classifying multiple and different types of digital modulation methods (64QAM, 2PSK, 4PSK, 8PSK, 4ASK, 2FSK, 4FSK, 8FSK). This paper focuses on trying to recognize the type of digital modulation using the artificial neural network (ANN) with its complex algorithm to boost the performance and increase the noise immunity of the system. This system succeeded in recognizing all the digital modulation types under the current study without any prior information. The proposed system used 8 signal features that were used to classify these 8 modulation methods. The system succeeded in achieving a recognition ratio of at least 68% for experimental signals on a signal to noise ratio (SNR = 5dB) and 89.1% for experimental signals at (SNR = 10dB) and 91% for experimental signals at (SNR = 15dB) for a channel with Additive White Gaussian Noise (AWGN)

A Space Communications Study Final Report, Sep. 15, 1965 - Sep. 15, 1966

Reception of frequency modulated signals passed through deterministic and random time-varying channel