Search results for "Communications system"
showing 10 items of 78 documents
Fast automated design of waveguide filters using aggressive space mapping with a new segmentation strategy and a hybrid optimization algorithm
2005
Waveguide filters are key elements present in many microwave and millimeter-wave communication systems. In recent times, ever-increasing efforts are being devoted to the development of automated computer-aided design (CAD) tools of such devices. In this paper, a novel CAD tool based on modal analysis methods, which improves the efficiency and robustness of the classical aggressive space-mapping technique, is presented for those purposes. The use of a new segmentation strategy and the hybridization of a specific combination of several well-known optimization algorithms is proposed. The CAD tool has been successfully validated with the practical design of several H-plane coupled cavity filter…
Waveguide filters for satellites
2007
This article describes the historical evolution, and its theoretical and technological features of waveguide filters. All-metal waveguide filters have been widely used in satellite payloads since the advent of the first space communication systems four decades ago. In this period, such technology has been continuously evolving due to the increasing requirements demanded to these components. Special attention has also been paid to present the most recent advances in the development of CAD tools for satellite filters, which are based on full-wave electromagnetic analysis methods. Finally, the compact solutions for the input and output stages of satellite payloads are focused on, thus consider…
Modelling the Doppler Power Spectrum of Non-Stationary Underwater Acoustic Channels Based on Doppler Measurements
2017
This paper proposes a non-stationary time-continuous simulation model for wideband shallow underwater acoustic (UWA) channels based on measured Doppler power spectrums (DPSs). Measurement-based channel simulators are essential for the test, optimization, and performance analysis of UWA communication systems. The aim is to fit the DPS of the simulation model to that of the measured UWA channel. The performance of the designed UWA channel simulator is assessed by comparing the average Doppler shift and Doppler spread of the channel simulator with the corresponding quantities of the measured UWA channel. The results of the assessment show a good match between the statistical quantities of the …
Noise and gain performance of PSA transistor series for personal communication systems vs. emitter number and operating conditions
1995
The booming market of communication system applications in the low microwave range put greater demands on the component performance at lower supply voltages and limited current consumption, as well as on production cost and integration level. In this work, we present the results of an extensive characterization activity carried out on several advanced polysilicon bipolar transistors as requested by the manufacturer. The devices were grouped according to their emitter finger number and were characterized over the 2-6 GHz frequency range in terms of noise, gain and scatterino parameters at different bias conditions. A comparative analysis has been performed to explore how the transistor perfo…
A Non-Stationary MIMO Vehicle-to-Vehicle Channel Model Derived from the Geometrical Street Model
2011
In this paper, we derive a non-stationary multiple-input multiple-output (MIMO) vehicle-to-vehicle (V2V) channel model from the geometrical street model. Single-bounce scattering is assumed for both fixed and moving scatterers. The high mobility of the transmitter, the receiver, and the surrounding vehicles results in time-variant angles-of-departure (AODs) and angles-of-arrival (AOAs). This fact makes the model non-stationary. Starting from the geometrical model, an analytical expression is derived for the channel gain taking into account the impact of fixed and moving scatterers. The statistical properties of the proposed channel model are studied. Analytical solutions are provided for th…
Electromagnetic immunity analysis of a new interface device with power line communication for smart grid and energy storage applications
2013
An analysis of EMC standards related to smart grid devices with PLC port has been carried out and the standardization lacks have been pointed out with reference to the evaluation of electromagnetic immunity to narrowband, coming from other communication systems connected to the grid, and RF disturbances conducted disturbances, usually present in a power grid. In particular, the paper analyses the electromagnetic conducted immunity of a new interface protection device (ID) for smart grid and energy storage applications. The new ID is equipped with a measuring board, a STM32 microcontroller, for data elaboration and memorization, and a ST7580 N-PSK powerline transceiver. An experimental test …
A generalized method for the design of ergodic sum-of-cisoids simulators for multiple uncorrelated rayleigh fading channels
2010
In this paper, we present a new method for the design of ergodic sum-of-sinusoids (SOS) simulation models for multiple uncorrelated Rayleigh fading channels. The method, which is intended for a special class of SOS models, known as sum-of-cisoids (SOC) models, can be used to generate an arbitrary number of uncorrelated Rayleigh fading waveforms with specified Doppler power spectral characteristics. This is in contrast to the SOS simulators currently available in the open literature that have been designed under the isotropic scattering assumption, which are limited to the simulation of uncorrelated channels characterized by Clarke's U-shaped Doppler power spectral density (DPSD). The excell…
The Design of Secure and Efficient P2PSIP Communication Systems
2010
Recently, both academia and industry have initiated research projects directed on integration of P2PSIP paradigm into communication systems. In this paradigm, P2P network stores most of the network information among participating peers without help of the central servers. The concept of self-configuration, self-establishment greatly improves the robustness of the network system compared with the traditional Client/Server based systems. In this paper, we propose a system architecture for constructing efficient and secure P2PSIP communication systems. The proposed approach includes three-layer hierarchical overlay division, peer identifier assignment, cache based efficiency enhancement, proxy…
Filtering out intersymbol interference in spread-spectrum communication systems
1979
In this letter the transfer characteristic of the optimum filter suitable for eliminating intersymbol interference in pseudo-noise spread-spectrum communication systems is determined. Such a characteristic is independent of the code sequence employed.
A hybrid network for maritime on-board communications
2012
Current maritime on-board communications have to be enhanced for safety and security, where ubiquitous technologies can help, together with providing comfort and convenience to the crew and passengers. Employing wireless sensor networks on board is one recent practice of implementing ubiquitous technology for ships, where further study is needed because of the connectivity challenges. Meanwhile, it is important for an on-board communication system to be reliable and flexible for handling emergency situations. In this paper, we propose a solution of employing ubiquitous technology on ships in a way that both connectivity and emergency handling are examined. Two key aspects of this proposal a…