Simple nonlinearity evaluation and modeling of low-noise amplifiers with application to radio astronomy receivers

This paper describes a comparative nonlinear analysis of low-noise amplifiers (LNAs) under different stimuli for use in astronomical applications. Wide-band Gaussian-noise input signals, together with the high values of gain required, make that figures of merit, such as the 1 dB compression (1 dBc) point of amplifiers, become crucial in the design process of radiometric receivers in order to guarantee the linearity in their nominal operation. The typical method to obtain the 1 dBc point is by using single-tone excitation signals to get the nonlinear amplitude to amplitude (AM-AM) characteristic but, as will be shown in the paper, in radiometers, the nature of the wide-band Gaussian-noise excitation signals makes the amplifiers present higher nonlinearity than when using single tone excitation signals. Therefore, in order to analyze the suitability of the LNA’s nominal operation, the 1 dBc point has to be obtained, but using realistic excitation signals. In this work, an analytical study of compression effects in amplifiers due to excitation signals composed of several tones is reported. Moreover, LNA nonlinear characteristics, as AM-AM, total distortion, and power to distortion ratio, have been obtained by simulation and measurement with wide-band Gaussian-noise excitation signals. This kind of signal can be considered as a limit case of a multitone signal, when the number of tones is very high. The work is illustrated by means of the extraction of realistic nonlinear characteristics, through simulation and measurement, of a 31 GHz back-end module LNA used in the radiometer of the QUIJOTE (Q U I JOint TEnerife) CMB experimen

A methodology for the design of application-specific cyber-physical social sensing co-simulators

Cyber-Physical Social Sensing (CPSS) is a new trend in the context of pervasive sensing. In these new systems, various domains coexist in time, evolve together and influence each other. Thus, application-specific tools are necessary for specifying and validating designs and simulating systems. However, nowadays, different tools are employed to simulate each domain independently. Mainly, the cause of the lack of co-simulation instruments to simulate all domains together is the extreme difficulty of combining and synchronizing various tools. In order to reduce that difficulty, an adequate architecture for the final co-simulator must be selected. Therefore, in this paper the authors investigate and propose a methodology for the design of CPSS co-simulation tools. The paper describes the four steps that software architects should follow in order to design the most adequate co-simulator for a certain application, considering the final users’ needs and requirements and various additional factors such as the development team’s experience. Moreover, the first practical use case of the proposed methodology is provided. An experimental validation is also included in order to evaluate the performing of the proposed co-simulator and to determine the correctness of the proposal

Some Modeling Aspects in the Simulation of Digital Links

International Telemetering Conference Proceedings / November 14-16, 1978 / Hyatt House Hotel, Los Angeles, CaliforniaComputer simulation of satellite digital links has become a useful tool for the accurate estimation of system bit error rate (BER) performance. This paper describes a simulation facility developed for such a purpose, and in particular discusses two aspects of modeling that bear on the accuracy of the system representation, namely the inclusion of uplink noise and the treatment of carrier phase tracking.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

On the Characterization of Noise in the Simulation of Nonlinear Wideband Satellite Digital Links

International Telemetering Conference Proceedings / October 14-16, 1980 / Bahia Hotel, San Diego, CaliforniaThe prediction of performance (BER) for a digital satellite link possessing typical impairments is a difficult analytical undertaking. When, further, the repeater is nonlinear and the uplink noise is nonnegligible, the difficulty of an analytical approach is greatly compounded. Consequently simulation is becoming increasingly common as a tool for solving the BER-prediction problem. It is often assumed, however, that a link is characterized by a single Gaussian noise source at the receiver. This assumption can lead to considerable error in the weak uplink nonlinear system. For the latter situation we consider in this paper the problem of characterizing an equivalent single noise source at the receiver, which will better account for actual system behavior than the Gaussian source. For this equivalent source we postulate that the pdf is drawn from a family of the form const x exp [ - | x | v] and obtain through simulation the BER performance as a function of v. Comparing these results with Monte Carlo simulation runs shows the possibility of approximately characterizing the complex system's behavior by a single non-Gaussian noise source.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection