Laisvai pasirenkamos trukmės ir pozicijos impulsų sekos ultragarsinėms vizualizacijos ir matavimo sistemoms

The quality of the ultrasonic measurements is determined by the received signal energy, bandwidth and correlation properties. Ultrasonic transducers and signal propagation alters the spectral content of signals, the signal-to-noise ratio and correlation properties decrease. Conventional signals do not allow these losses to be corrected or inefficiently exploit the amplitude-time range dedicated for the excitation, excitation electronics are complex. New rectangular spread spectrum excitation signals have been proposed: arbitrary position and width pulse sequences (APWP). The novelty of the proposed APWP approach is that the optimization of the APWP sequence accounts the system transmission function, thus enhancing the desired signal properties. Signals combine the useful properties of rectangular pulses and spread spectrum signals, allow to control the correlation properties and spectral shape, do not require complex excitation electronics, and efficiently utilize the amplitude-time range dedicated for the excitation. The proposed signals provide an opportunity to improve the measurement quality when measuring flow, distance or thickness. The results of the work are also applicable in imaging, because the wider spectrum yields a better resolution, while smaller sidelobes and a higher signal-to-noise ratio allow to increase the contrast. Signals are extremely effective in spectroscopy when seeking to maximize the spectral coverage, its smoothness and uniform signal-to-noise ratio over the frequency range

Avionics system design for high energy fields: A guide for the designer and airworthiness specialist

Because of the significant differences in transient susceptibility, the use of digital electronics in flight critical systems, and the reduced shielding effects of composite materials, there is a definite need to define pracitices which will minimize electromagnetic susceptibility, to investigate the operational environment, and to develop appropriate testing methods for flight critical systems. The design practices which will lead to reduced electromagnetic susceptibility of avionics systems in high energy fields is described. The levels of emission that can be anticipated from generic digital devices. It is assumed that as data processing equipment becomes an ever larger part of the avionics package, the construction methods of the data processing industry will increasingly carry over into aircraft. In Appendix 1 tentative revisions to RTCA DO-160B, Environmental Conditions and Test Procedures for Airborne Equipment, are presented. These revisions are intended to safeguard flight critical systems from the effects of high energy electromagnetic fields. A very extensive and useful bibliography on both electromagnetic compatibility and avionics issues is included

A study of multiplex data bus techniques for the space shuttle

A comprehensive technology base for the design of a multiplexed data bus subsystem is provided. Extensive analyses, both analytical and empirical, were performed. Subjects covered are classified under the following headings: requirements identification and analysis; transmission media studies; signal design and detection studies; synchronization, timing, and control studies; user-subsystem interface studies; operational reliability analyses; design of candidate data bus configurations; and evaluation of candidate data bus designs

Indoor Visible Light Communication:A Tutorial and Survey

Abstract With the advancement of solid-state devices for lighting, illumination is on the verge of being completely restructured. This revolution comes with numerous advantages and viable opportunities that can transform the world of wireless communications for the better. Solid-state LEDs are rapidly replacing the contemporary incandescent and fluorescent lamps. In addition to their high energy efficiency, LEDs are desirable for their low heat generation, long lifespan, and their capability to switch on and off at an extremely high rate. The ability of switching between different levels of luminous intensity at such a rate has enabled the inception of a new communication technology referred to as visible light communication (VLC). With this technology, the LED lamps are additionally being used for data transmission. This paper provides a tutorial and a survey of VLC in terms of the design, development, and evaluation techniques as well as current challenges and their envisioned solutions. The focus of this paper is mainly directed towards an indoor setup. An overview of VLC, theory of illumination, system receivers, system architecture, and ongoing developments are provided. We further provide some baseline simulation results to give a technical background on the performance of VLC systems. Moreover, we provide the potential of incorporating VLC techniques in the current and upcoming technologies such as fifth-generation (5G), beyond fifth-generation (B5G) wireless communication trends including sixth-generation (6G), and intelligent reflective surfaces (IRSs) among others

A radio frequency DC-to-DC resonant power converter

Thesis (Elect. E.)--Massachusetts Institute of Technology, Dept. of Electrical Engieering and Computer Science, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.Bibliography: leaves 136-139.by Andrew Franklin Goldberg.Elect.E