Quadrature Components Forming Method for Homodyne Acousto-Optic Spectrum Analyzer

Aronov, L. A.; Ushakov, Victor N.

doi:10.32603/1993-8985-2019-22-2-53-61

Cited by 3 publications

(1 citation statement)

References 4 publications

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“…The possibility of reducing the time for obtaining a spectrum estimate is considered in [32]. The authors proposed methods for the formation of quadrature components, which can reduce the time to obtain an estimate of the spectrum in interference acousto-optic spectrum analyzers, and also, if necessary, simplify their implementation.…”

Section: Main Partmentioning

confidence: 99%

Means of Improving the Quality of Service of the Computer Network of the Forensic Information System

Mozhaiev¹,

Melashchenko²,

Roh³

et al. 2020

Innovative Technologies and Scientific Solutions for Industries

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The relevance of research. In modern forensic practice, computer networks (CN) are an integral part of computer-technical examination, therefore, ensuring their normal functioning becomes a vitally important task. In this regard, the theory of the construction, modification and operation of digital telecommunication systems raises a fairly general problem of digital signal processing, network synchronization and its stability. A solution to this problem was devoted to research, which analyzed the characteristics of the stability of the network and proposed methods for measuring the physical parameters that determine it. Many of the studies conducted were based on the use of frequency measurements in communication channels of computer networks for transmitting information. Acousto-optic spectrum analyzers (AOSAs) are widely used in forensic information system networks improving the QoS of forensic computer networks. The subject of the research: resolution of acousto-optical spectrum analyzers. The purpose of the research to improve the quality of diagnostics of parameters of computer information transmission networks based on the use of the developed signal processing technique in acousto-optic spectrum analyzers, which allows increasing the resolution of AOSA by increasing the frequency resolution of two non-simultaneous long-duration radio pulses. The results of the research. The research presents analysis of the influence of the frequency parameters of the computer network on the implementation of the relevant requirements for quality of service. Studies have been carried out on possible ways to increase the resolution of AOAC in frequency. The nonlinear characteristics of AOSA were studied, which made it possible to modernize methods for increasing the frequency resolution. The classical method of processing radar signals is used, which allows determining the delay time of arrival of a sufficiently long pulse with an accuracy significantly exceeding the pulse size. When analyzing the operation of AOSA, it is taken into account that the signal photoelectron flux in the acousto-optical spectrum analyzer is known to be described by the Poisson distribution. But one of the main properties of random variables distributed according to Poisson's law is the lack of cross-correlation of the components of the Poisson stream. This assumption can significantly increase the frequency resolution of AOSA. Conclusions. The research ascertains analytical relationship for the dispersion of the signal frequency measurement. The research proposes a technique for processing signals in AOSA, allowing to increase the resolution of AOSA by increasing the frequency resolution of two non-simultaneous radio pulses of long duration.

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Section: Main Partmentioning

confidence: 99%

Means of Improving the Quality of Service of the Computer Network of the Forensic Information System

Mozhaiev¹,

Melashchenko²,

Roh³

et al. 2020

Innovative Technologies and Scientific Solutions for Industries

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On Using Periodic Reference Signal in Homodyne Acousto-Optic Spectrum Analyzer

Aronov

Dobrolenskii

Ushakov

2019

Izv. vysš. učebn. zaved. Ross., Radioèlektron.

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Introduction. For a homodyne acousto-optic spectrum analyzer functioning a reference optical channel must be organized. The signal in this channel should provide uniform reference illumination throughout the spatial frequency range. In the general case, the spectrum analyzer functioning can be considered with a continuous photosensor and photosensor with charge accumulation. With the last one, the signal in the reference channel is proposed to be a wideband pulses periodic sequence. Objective. Analyze the spectrum analyzer functioning with a periodic reference signal. Materials and methods. We derive the mathematical expression to describe the influence of the reference signal structure on the analyzer’s output signal for the cases of continuous photosensor and photosensor with charge accumulation. Results. It is shown that in the case of continuous photosensor, the reference signal periodicity does not lead to characteristics degradation. However, in the case of many frequency resolution points it is impractical, since each photodetector signal is parallel, processing is required: filtering, amplification and digitization. In the case of using of the charge accumulation sensor, the discrete frequency grid appears, which means signals omissions in frequency. This can be avoided by choosing the accumulation time equal to the minimum among the values of the acousto-optic modulator time aperture and the reference signal period, which is hard to implement, or still leads to the signal omissions in frequency or time. Conclusion. To perform a real-time mode in the homodyne acousto-optic spectrum analyzer, the reference signal must be either non-periodic, which raises the question of its synthesis, or a continuous photodiode array should be used.

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Statistic Model of Homodyne Acousto-Optic Spectrum Analyzer

Aronov¹,

Доброленский²,

Kulak³

2020

Izv. vysš. učebn. zaved. Ross., Radioèlektron.

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Introduction. Acousto-optic spectrum analyzers interferometric schemes have been developed to increase dynamic range. It was assumed that dynamic range, expressed in dB, would double. An expected increase was not achieved yet.Aim. To analyze the homodyne acousto-optic spectrum analyzer noise characteristics, to estimate the signal-tonoise ratio and the dynamic range.Materials and methods. A mathematical model was compiled which took into account the need to form quadrature components to obtain an amplitude spectrum of an input signal, shot noise and readout noise.Results. An interferometric scheme did not allow to achieve dynamic range doubling compared to an acoustooptical power spectrum analyzer. The dynamic range increase was less than 1.35 dB. Constant illumination led to a significant increase of the spectrum analyzer self-noise due to shot noise, compared to which thermal noise and readout noise became insignificant. The spurious-free dynamic range estimation expression was obtained. It was prior determined by acousto-optic interaction nonlinearity. With typical analyzer blocks parameters the spurious-free dynamic range covered a single-signal dynamic range. Signal-to-noise ratio estimation expression was presented.Conclusion. The homodyne acousto-optic spectrum analyzer single-signal dynamic range is determined primarily by the photosensor saturation charge. One needs to optimize their relation by taking into account light source power, acousto-optical modulator diffraction efficiency and photosensor saturation charge. Presented noise model gives more accurate estimation of the dynamic range with an error of 1 dB.

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Quadrature Components Forming Method for Homodyne Acousto-Optic Spectrum Analyzer

Cited by 3 publications

References 4 publications

Means of Improving the Quality of Service of the Computer Network of the Forensic Information System

Means of Improving the Quality of Service of the Computer Network of the Forensic Information System

On Using Periodic Reference Signal in Homodyne Acousto-Optic Spectrum Analyzer

Statistic Model of Homodyne Acousto-Optic Spectrum Analyzer

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