Structural optimization of Dicke-type radiometer
01 Oct 2016-pp 171-174
TL;DR: In this article, a block diagram of signal processing in the Dicke-type radiometer was developed on the basis of the theory of optimal statistical decisions and parameters estimates of probabilistic distributions.
Abstract: Algorithms and block diagrams of signal processing in the Dicke-type radiometer are synthesized on the basis of the theory of optimal statistical decisions and parameters estimates of probabilistic distributions. Limit errors of required parameters estimates in the received optimal algorithms and potential fluctuation sensitivity of the developed block diagrams are investigated.
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01 Jul 2018
TL;DR: A logical connection is formed between the key elements of the microwave radiation theory, the mathematical apparatus for processing UWB signals and the fundamentals of the optimal signal processing algorithms synthesis.
Abstract: Passive radars are such radars that record and process signals of the objects own radiation within the radio wave band. They are used to solve a wide range of remote sensing problems. The observations registered by such radars are a mixture of stochastic signals of the investigated and interfering objects, as well as the internal noise of the receiver. Signals and noise are completely random, and their statistical characteristics are the same. Another feature of the transmitting radio thermal signals is that their emission spectrum is ultra-wideband (UWB) (except for polyatomic gases, which are characterized by discrete absorption and emission lines). Therefore, it is expedient to provide wide- or UWB for the passive radars operating frequencies band. Transition to UWB signal processing requires the improvement of the passive UWB radars theory. This theory should be able to synthesize new algorithms for signal processing and reveal the physical essence of parameter estimates at the output of the radar. This will allow solving the inverse problems of estimating the parameters and characteristics of the objects. Results of many years of research are summarized in this paper, a logical connection is formed between the key elements of the microwave radiation theory, the mathematical apparatus for processing UWB signals and the fundamentals of the optimal signal processing algorithms synthesis. Examples of the signal processing algorithm synthesis in a single- and a multichannel passive radar are also given.
4 citations
Cites result from "Structural optimization of Dicke-ty..."
...The subsection generalizes the results of the studies [15-22]....
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24 May 2017
TL;DR: In this article, a ground radiometric complex, working on 40 GHz and 94 GHz frequencies and providing remote continuous measurements of full vertical atmosphere attenuation, effective temperature values and liquid-water content of clouds, integral content of vaporous moisture in atmosphere.
Abstract: Short description of new ground radiometric complex, working on 40 GHz and 94 GHz frequencies and providing remote continuous measurements of full vertical atmosphere attenuation, effective temperature values and liquid-water content of clouds, integral content of vaporous moisture in atmosphere. The feature of the complex is the availability of digital signal processing of detected signals mode.
4 citations
21 Sep 2020
TL;DR: The optimization problem of surfaces radar cross section (RCS) estimation as a statistical characteristic of spatially inhomogeneous random processes in airborne radar systems with multi-channel signal processing is solved and obtained superresolution methods for evaluating the RCS.
Abstract: The optimization problem of surfaces radar cross section (RCS) estimation as a statistical characteristic of spatially inhomogeneous random processes in airborne radar systems with multi-channel signal processing is solved. Using the generalized problem statement of detecting reflected electromagnetic fields with a multi-element antenna array without specifying spatial processing made it possible to obtain the optimal observation mode in radars with aperture synthesis. Obtained mathematical apparatus can be used as the basis for the development of cognitive radars, because it allows to get most of the existing types of surface observation under certain restrictions. Taking into account a priori information on the statistical characteristics of the scattered spatiotemporal fields, it was possible to obtain superresolution methods for evaluating the RCS. These methods differ from traditional methods in the presence of decorrelation operation of the received signals.
2 citations
Cites methods from "Structural optimization of Dicke-ty..."
...We will write the likelihood functional for the stochastic model of received signals, as shown in [12-15] in the following form:...
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21 Sep 2020
TL;DR: This method summarizes several modern modes of terrain observation and is fully consistent with current trends in the creation of cognitive radars with the possibility of restructuring the beam pattern in space and adaptive reception of reflected signals.
Abstract: Using the statistical theory of optimization of radio engineering systems the optimal method for the formation of coherent radar images of surfaces in airborne synthetic aperture radar with planar antenna arrays is obtained. This method summarizes several modern modes of terrain observation and is fully consistent with current trends in the creation of cognitive radars with the possibility of restructuring the beam pattern in space and adaptive reception of reflected signals. Possible modifications of the obtained optimal method for the operation of high-precision airborne radars with a wide swath are presented. The analysis of the limiting errors of measurement of the desired parameters is carried out and analytical expressions are obtained for the nonstationary ambiguity function of the resulting structure of an airborne radar with a planar antenna array.
2 citations
Cites background or methods from "Structural optimization of Dicke-ty..."
...The obtained form of equation (9) is not simple and has already been interpreted in [12-15]....
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...We write the likelihood functional in the following form, as shown in [12-15],...
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TL;DR: The algorithm to measure flight altitude for a helicopter or an unmanned aerial vehicle based on the processing of wideband and ultra-wideband pulsed stochastic signals is synthesized for the first time by the maximum-likelihood method.
Abstract: Radio altimeters are an important component of modern helicopter on-board systems. These devices currently involve the use of narrowband deterministic signals, that limits their potential technical characteristics. Given the significant breakthrough in the development of wideband and ultra-wideband radio electronics, it is promising to create on-board radio complexes capable of obtaining the necessary information using wideband stochastic signals. At the same time, when developing such complexes, it is important to use optimal synthesis methods for radio systems, which will allow optimal signal processing algorithms and potential accuracy parameters to be obtained. In this work, the algorithm to measure flight altitude for a helicopter or an unmanned aerial vehicle based on the processing of wideband and ultra-wideband pulsed stochastic signals is synthesized for the first time by the maximum-likelihood method. When formulating the problem, the mathematical model of the signal and observation is specified, and their statistical characteristics are investigated. The peculiarity of the synthesis task is the use of a noise pulse transmitter, which implements the function of an underlying surface illuminator, as well as considering the signal structure destruction during its radiation, propagation, and reflection. This signal shape destruction makes it impossible to synthesize a radar with internally coherent processing when working on one receiving antenna. In accordance with the synthesized algorithm, a simulation model of a pulsed radar with a stochastic probing signal has been developed and the results of its modeling are presented.
2 citations
References
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TL;DR: The experimentally measured root mean square fluctuation of the output meter of a microwave radiometer compares favorably with a theoretical value of 0.4°C, which corresponds to a minimum detectable power of 10-16 watt.
Abstract: The connection between Johnson noise and blackbody radiation is discussed, using a simple thermodynamic model. A microwave radiometer is described together with its theory of operation. The experimentally measured root mean square fluctuation of the output meter of a microwave radiometer (0.4°C) compares favorably with a theoretical value of 0.46°C. With an r-f band width of 16 mc/sec., the 0.4°C corresponds to a minimum detectable power of 10-16 watt. The method of calibrating using a variable temperature resistive load is described.
941 citations
"Structural optimization of Dicke-ty..." refers methods in this paper
...There are many effective methods [3−5] of radio thermal signal processing which are realized in total-power radiometer, Dicke-type type radiometer, correlation radiometer, interferometric systems, etc. Radiometers with modulation of desired signal (signal from the antenna) are widely used in remote sensing and was invented in 1946 by professor Robert Henry Dicke [6]....
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...Radiometers with modulation of desired signal (signal from the antenna) are widely used in remote sensing and was invented in 1946 by professor Robert Henry Dicke [6]....
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01 Jan 2006
TL;DR: The paper presents some new methods for early breast cancer detection using microwaves, including microwave impedance tomography, termography and microwave radiometry, combined methods microwave and ultra-acustic image and confocal microwave imaging.
Abstract: The paper presents some new methods for early breast cancer detection using microwaves. On describe the following methods and techniques: microwave impedance tomography, termography and microwave radiometry, combined methods microwave and ultra-acustic image and confocal microwave imaging. We make an analysis of advantages and disadvantages of every method and also physical principles of microwave thermography.
24 citations
31 Oct 2013
TL;DR: A new concept for solving statistical synthesis problems of radiometric devices and systems (RDS) is developed and the appropriateness of using the Kravchenko weighting functions for refinement of primary radiometric images in radiometric scanning devices is substantiated.
Abstract: A new concept for solving statistical synthesis problems of radiometric devices and systems (RDS) is developed. The reasonability of using ultra-wideband (UWB) RDSs is substantiated. The basic data of mathematical apparatus of V-transforms employed when processing space-time UWB fields and their statistical characteristics is given. A wide class of UWB RDS statistical synthesis problems (compensation, zero-type, modified modulation type, modulation compensation type, multi-antenna systems including cross-correlation-compensation systems and aperture synthesis systems) of stationary and scanning types are solved. The appropriateness of using the Kravchenko weighting functions for refinement of primary radiometric images in radiometric scanning devices is substantiated.
18 citations
TL;DR: In this article, the properties of spatial and temporal fluctuations of atmospheric absorption and emission at millimeter and centimeter wavelengths are presented. And the authors show that in cloudless weather, the intensity of fluctuations at these wavelengths is determined mainly by random fluctuations of the humidity field.
Abstract: [1] Characteristics of spatial and temporal fluctuations of atmospheric absorption and emission at millimeter and centimeter wavelengths are presented Theoretical relations and experimental data are given on structure functions of absorption and brightness temperature at wavelengths of 08 and 135 cm It is shown that in cloudless weather the intensity of fluctuations at these wavelengths is determined mainly by random fluctuations of the humidity field Under cloudy conditions the intensity of fluctuations of microwave atmospheric radiation grows, with stratiform and cumuliform clouds differently affecting the character of the space-time dependency of fluctuations
13 citations