Mathematical models for radio signals dynamic range prediction in space-scattered mobile radiocommunication networks

The spectrum analysis of the periodic sequence radio pulses is often described in textbooks. However, if this method is applied to short radio pulses with a large period between them, then large errors occur. In this article, we described a new method of pulse gating. This method allows us to measure the spectral density of radio signals with high duty cycle. The main advantages of our method are a high signal-to-noise ratio, a large dynamic range of measurements, and a higher accuracy of spectral density measurements.

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Connectivity and routes in large geometric network hypergraphs

Informatization and communication ◽

10.34219/2078-8320-2021-12-2-76-80 ◽

2021 ◽

pp. 76-80

Author(s):

A.I. Mikov ◽

A.A. Mikov

Keyword(s):

Mathematical Models ◽

Computer Networks ◽

Mathematical Expectation ◽

Network Nodes ◽

Shortest Route ◽

Radio Signals ◽

Geometric Hypergraphs

Random geometric hypergraphs are considered as mathematical models of large wireless computer networks. The dependences of the mathematical expectation of the number of hyper-edges in random geometric hypergraphs on the radii of reliable reception / transmission of radio signals by network nodes, as well as on the number of vertices in the hyper- graph are studied. The concepts of the shortest route in a geometric hypergraph are discussed. Calculations of the probabil- ity of connectivity of large random geometric hypergraphs, the mathematical expectation of the diameter of hypergraphs and its change with a change in the radii of the nodes are carried out. The presentation of the results is accompanied by graphs.

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Techniques for Coping with Radio Frequency Interference

Symposium - International Astronomical Union ◽

10.1017/s0074180900164228 ◽

2001 ◽

Vol 196 ◽

pp. 279-287

Author(s):

J. R. Fisher

Keyword(s):

Adaptive Filters ◽

Dynamic Range ◽

High Dynamic Range ◽

Spectrum Management ◽

Low Noise ◽

Radio Signals ◽

Management Effort ◽

Technical Solutions ◽

Spurious Radiation

As a complement to spectrum management efforts by radio astronomers a number of observatories and research groups around the world have begun looking into technical solutions to the problem of separating weak cosmic radiation from man-made radio signals. Some of the technical research now getting underway includes: high dynamic range receivers, low-noise superconducting filters, passive digital filtering, adaptive filters, adaptive sidelobe nulling, multi-feed correlation of RFI, and various techniques for signal blanking.Increased technical support to spectrum management can also be provided in the form of accurate and statistically significant characterization of the radio environment, empirical and theoretical improvement of over-the-horizon propagation models, and timely measurements of spurious radiation falling in the protected radio astronomy bands.Finally, credibility of our spectrum management effort can only be maintained by making sure that local radiation under the control of our radio observatories is in compliance with the field strength limits of Recommendation ITU-R R.A.769. This requires sensitive radiation measurements and often shielding of digital equipment, microwave ovens, test equipment, local oscillators, etc.

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COMBINATION OF SYNTHETIC HIGH-PERFORMANCE RF AMPLIFICATION TECHNIQUES

T-Comm ◽

10.36724/2072-8735-2021-15-9-11-16 ◽

2021 ◽

Vol 15 (9) ◽

pp. 11-16

Author(s):

Oleg V. Varlamov ◽

◽

Dang C. Nguyen ◽

Sergey E. Grychkin ◽

◽

...

Keyword(s):

High Performance ◽

High Efficiency ◽

Dynamic Range ◽

Supply Voltage ◽

Rf Power Amplifiers ◽

Rf Power ◽

Crest Factor ◽

Combined Use ◽

Radio Signals ◽

Element Base

To amplify modern high crest factor telecommunication radio signals with high efficiency, switching operation modes of transistors and synthetic amplification methods are used. The most common of these are the Kahn method (EER – envelope elimination and restoration) and the outphasing method. However, application of these methods has a number of technological (in terms of element base capabilities) limitations on the bandwidth and dynamic range of amplified signal. To expand high-efficiency RF power amplifiers field of application, the possibilities of combination several different synthetic amplification techniques are being considered. Expressions are obtained for the theoretically achievable efficiency when combining the outphasing method with a bridge power combiner and pulse-step modulation of supply voltage. The dependence of average efficiency on the number of supply voltage levels is determined. RF amplified signal bandwidth and its dynamic range determine the minimum required pulse width of the PWM modulator for the EER amplifier. Variants of these characteristics dependence on the number of supply voltage levels are discussed with combined use of PWM and pulse-step modulation of the supply voltage. Directions for further research are formulated.

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Properties of geometric hypergraphs of wireless computer networks

Informatization and communication ◽

10.34219/2078-8320-2020-11-4-60-66 ◽

2020 ◽

Vol 4 ◽

pp. 60-66

Author(s):

Alexander I. Mikov ◽

◽

Alexander A. Mikov

Keyword(s):

Standard Deviation ◽

Mathematical Models ◽

Computer Networks ◽

Mathematical Expectation ◽

Computer Network ◽

Natural Form ◽

Network Nodes ◽

Radio Signals ◽

Geometric Hypergraphs ◽

Random Hypergraphs

Mathematical models of wireless computer networks are considered, reflecting two types of interaction between nodes of the same network — broadcast and routing. A natural form of representation of such a network is a hypergraph, in which the direct links between nodes that do not require routing are specified by the hyper-edges. The routes are chains of hyper-edges. The concepts of geometric and random hypergraphs are introduced, the dependences of the probabilistic characteristics of random geometric hypergraphs on the number of vertices and radii of reliable reception / transmission of radio signals by network nodes are studied — the mathematical expectation and standard deviation of the number of hyperedges, degrees of hyperedges. The properties of dynamic geometric hypergraphs are discussed, their influence on the connectivity of a computer network, and the requirements for algorithms for managing connectivity in terms of hypergraphs are formulated.

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Slow-Scan CCD Observation of Backscattering Patterns in SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131176 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1308-1309

Author(s):

F. Ouyang ◽

D. A. Ray ◽

O. L. Krivanek

Keyword(s):

Electron Beam ◽

Electron Microscope ◽

Scanning Electron Microscope ◽

Dynamic Range ◽

High Sensitivity ◽

Lens System ◽

Wide Dynamic Range ◽

Peltier Cooler ◽

Diffraction Patterns ◽

Scanning Electron

Electron backscattering Kikuchi diffraction patterns (BKDP) reveal useful information about the structure and orientation of crystals under study. With the well focused electron beam in a scanning electron microscope (SEM), one can use BKDP as a microanalysis tool. BKDPs have been recorded in SEMs using a phosphor screen coupled to an intensified TV camera through a lens system, and by photographic negatives. With the development of fiber-optically coupled slow scan CCD (SSC) cameras for electron beam imaging, one can take advantage of their high sensitivity and wide dynamic range for observing BKDP in SEM.We have used the Gatan 690 SSC camera to observe backscattering patterns in a JEOL JSM-840A SEM. The CCD sensor has an active area of 13.25 mm × 8.83 mm and 576 × 384 pixels. The camera head, which consists of a single crystal YAG scintillator fiber optically coupled to the CCD chip, is located inside the SEM specimen chamber. The whole camera head is cooled to about -30°C by a Peltier cooler, which permits long integration times (up to 100 seconds).

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Quantitative energy-filtered electron diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172693 ◽

1994 ◽

Vol 52 ◽

pp. 992-993

Author(s):

R. Vincent

Keyword(s):

Electron Diffraction ◽

Inelastic Scattering ◽

Dynamic Range ◽

Electron Optics ◽

Surface Layers ◽

High Brightness ◽

Inclined Surfaces ◽

Perfect Symmetry ◽

Amorphous Surface ◽

The Ideal

Microanalysis and diffraction on a sub-nanometre scale have become practical in modern TEMs due to the high brightness of field emission sources combined with the short mean free paths associated with both elastic and inelastic scattering of incident electrons by the specimen. However, development of electron diffraction as a quantitative discipline has been limited by the absence of any generalised theory for dynamical inelastic scattering. These problems have been simplified by recent innovations, principally the introduction of spectrometers such as the Gatan imaging filter (GIF) and the Zeiss omega filter, which remove the inelastic electrons, combined with annual improvements in the speed of computer workstations and the availability of solid-state detectors with high resolution, sensitivity and dynamic range.Comparison of experimental data with dynamical calculations imposes stringent requirements on the specimen and the electron optics, even when the inelastic component has been removed. For example, no experimental CBED pattern ever has perfect symmetry, departures from the ideal being attributable to residual strain, thickness averaging, inclined surfaces, incomplete cells and amorphous surface layers.

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Direct measurement of electron-diffraction-pattern intensities using an energy loss spectrometer

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155311 ◽

1989 ◽

Vol 47 ◽

pp. 668-669

Author(s):

A. G. Jackson ◽

M. Rowe

Keyword(s):

Thermal Effects ◽

Dynamic Range ◽

Scattering Amplitude ◽

Dynamical Theory ◽

Site Symmetry ◽

Proof Of Concept ◽

Parallel Acquisition ◽

Kinematic Approximation ◽

Speed Up ◽

Structure Calculations

Diffraction intensities from intermetallic compounds are, in the kinematic approximation, proportional to the scattering amplitude from the element doing the scattering. More detailed calculations have shown that site symmetry and occupation by various atom species also affects the intensity in a diffracted beam. [1] Hence, by measuring the intensities of beams, or their ratios, the occupancy can be estimated. Measurement of the intensity values also allows structure calculations to be made to determine the spatial distribution of the potentials doing the scattering. Thermal effects are also present as a background contribution. Inelastic effects such as loss or absorption/excitation complicate the intensity behavior, and dynamical theory is required to estimate the intensity value.The dynamic range of currents in diffracted beams can be 104or 105:1. Hence, detection of such information requires a means for collecting the intensity over a signal-to-noise range beyond that obtainable with a single film plate, which has a S/N of about 103:1. Although such a collection system is not available currently, a simple system consisting of instrumentation on an existing STEM can be used as a proof of concept which has a S/N of about 255:1, limited by the 8 bit pixel attributes used in the electronics. Use of 24 bit pixel attributes would easily allowthe desired noise range to be attained in the processing instrumentation. The S/N of the scintillator used by the photoelectron sensor is about 106 to 1, well beyond the S/N goal. The trade-off that must be made is the time for acquiring the signal, since the pattern can be obtained in seconds using film plates, compared to 10 to 20 minutes for a pattern to be acquired using the digital scan. Parallel acquisition would, of course, speed up this process immensely.

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Development of imaging plate for a TEM and its characteristics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152471 ◽

1989 ◽

Vol 47 ◽

pp. 100-101

Author(s):

N. Mori ◽

T. Oikawa ◽

Y. Harada ◽

J. Miyahara ◽

T. Matsuo

Keyword(s):

Dynamic Range ◽

Protective Layer ◽

High Sensitivity ◽

Imaging Plate ◽

Phosphor Layer ◽

Imaging Device ◽

X Ray Imaging ◽

New Type ◽

Basic Characteristics ◽

Reading System

The Imaging Plate (IP) is a new type imaging device, which was developed for diagnostic x ray imaging. We have reported that usage of the IP for a TEM has many merits; those are high sensitivity, wide dynamic range, and good linearity. However in the previous report the reading system was prototype drum-type-scanner, and IP was also experimentally made, which phosphor layer was 50μm thick with no protective layer. So special care was needed to handle them, and they were used only to make sure the basic characteristics. In this article we report the result of newly developed reading, printing system and high resolution IP for practical use. We mainly discuss the characteristics of the IP here. (Precise performance concerned with the reader and other system are reported in the other article.)Fig.1 shows the schematic cross section of the IP. The IP consists of three parts; protective layer, phosphor layer and support.

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