scholarly journals MATHEMATICAL MODEL OF THE RECEIVING PATH OF DIGITAL COMMUNICATION LINES

T-Comm ◽  
2021 ◽  
Vol 15 (5) ◽  
pp. 52-57
Author(s):  
Vitaly G. Dovbnya ◽  
◽  
Dmitry S. Koptev ◽  
Keyword(s):  
Mathematical Model ◽  
Noise Immunity ◽  
Digital Communication ◽  
Automatic Gain Control ◽  
Clock Synchronization ◽  
Gain Control ◽  
Communication Line ◽  
Digital Signals ◽  
Dynamic Errors ◽  
Communication Lines

Modern trends in the development of digital communication lines of fixed information transmission services, as well as the characteristics of continuous channels today determine the noise immunity of radio receiving systems. The main directions of its increase in terms of the radio receiving device as a whole and the demodulator device in particular are as follows: reducing the frequency and nonlinear distortions of the signal in the linear path, increasing the stability and purity of the spectral line of oscillations of local oscillators, increasing the selectivity for the mirror and combination channels of reception, compensation for intersymbol and cross – polarization interference, improving the functioning of the automatic gain control device (reducing static and dynamic errors), improving the quality of the functioning of the carrier wave recovery device and the clock synchronization device. Taking into account all of the above factors in order to increase the overall noise immunity of a digital communication line is a very difficult and urgent task, the solution of which must begin with the development of a mathematical model of a continuous digital communication line channel. This article discusses the radio receiving path of a digital communication line in an urban environment. The obtained analytical expressions are aimed at interpreting the processes of converting digital signals in the structural elements of radio receiving systems. The originality of the mathematical model developed in the article lies in the fact that it additionally, in comparison with similar models, takes into account the following number of factors: frequency instability and phase fluctuations of oscillations of the local oscillator synthesizer, dynamic and static errors in the operation of automatic gain control devices, carrier vibration recovery devices and devices clock synchronization of radio receiving systems of digital signals.

scholarly journals Influence of synchronization errors оn the noise immunity of coherent reception of M-PSK signals

2019 ◽  
Vol 7 (5) ◽  
pp. 47-61 ◽  
Author(s):  
G. V. Kulikov ◽  
Nguyen Van Dung
Keyword(s):  
Information Transfer ◽  
Noise Immunity ◽  
Clock Synchronization ◽  
Signal To Noise Ratio ◽  
Dynamic Error ◽  
Radio Waves ◽  
Satellite Television ◽  
Synchronization Errors ◽  
Dynamic Errors ◽  
Ieee 802.11 Wireless Networks

Signals with multiple phase-shift keying (M-PSK) have long been successfully used for highspeed information transfer in many applications – a number of adopted protocols of IEEE 802.11 wireless networks, digital satellite television DVB-S, DVB-S2/S2X systems, cellular networks CDMA and others. The most important characteristic of such systems is their noise immunity, which depends not only on the propagation conditions of radio waves in the communication channel, but also on the quality of operation of the component nodes of the information transmission systems themselves. The paper investigates the influence of the inaccuracy of estimating the frequency and phase of the carrier and the inaccuracy of the clock synchronization system on the noise immunity of coherent reception of M-PSK signals. Analytical expressions were obtained by statistical radio engineering methods. The expressions allow calculating the dependence of the probability of a bit error on the signal-to-noise ratio for various errors of the receiver auxiliary systems. In this case, the magnitudes of the errors were assumed to be either constant (static error) or dynamically changing (dynamic error). The dynamic errors were modeled using the Monte Carlo method, and the dynamic errors themselves were assumed to be Gaussian random variables. It is shown that the inaccuracy of estimating these parameters strongly influences the noise immunity of the coherent reception of the M-PSK signal, and this effect increases with increasing signal positionality. Estimates of the maximum permissible errors of the analyzed systems are given. When M-PSK signals are received, a tolerable value of the frequency of the reference oscillations can be considered as a ∆ωTs value of about 0.05. The allowable inaccuracy of the carrier phase estimation depends on the positioning of the signal and varies from π/36–π/72 for 2PSK to π/180 for 32PSK. The allowable time offset of the clock moments can be considered the value of 3–5% of the clock interval duration.

scholarly journals EVALUATION OF THE INFLUENCE OF THE VALUE OF THE DYNAMIC RANGE OF THE RADIO RECEIVER ON THE NOISE IMMUNITY OF RECEIVING SIGNALS WITH QUADRATURE AMPLITUDE MODULATION

T-Comm ◽  
2021 ◽  
Vol 15 (6) ◽  
pp. 65-69
Author(s):  
Vitaly G. Dovbnya ◽  
◽  
Dmitry S. Koptev ◽  
Ivan G. Babanin ◽  
Alexander A. Knyazev ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Information Exchange ◽  
Noise Immunity ◽  
Digital Communication ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
Frequency Converter ◽  
Technical Requirements ◽  
Communication Lines

The improvement of digital communication lines of radio information transmission systems in the direction of increasing the complexity of the signal-code structures used, increasing the speed of information exchange, the use of modern channel compaction technologies, on the one hand, and the high complexity of the surrounding electromagnetic environment, on the other hand, objectively determines the need to improve the radio receiving systems of digital communication lines in the direction of increasing their noise immunity. In this regard, in order to justify the technical requirements for noise immunity to radio receiving systems of the designed transmission lines, it is advisable to take into account the basic indicators of the quality of functioning of the radio receiving device, in order to obtain analytical expressions and graphical dependencies for evaluating the noise immunity of receiving signals with more complex combined types of modulation (QAM-64 and higher), used and planned for use. Of the large number of indicators that characterize the dynamic range, the most informative and sufficiently characterize the quality of the linear path are: the dynamic range for reducing the transmission coefficient (compression) by 1 dB and the dynamic range for third-order intermodulation distortion. The effect of interference received on the side channels (which include combination and mirror), as well as on neighboring channels, limits the lower limit of the dynamic range of the receiving device and, as a result, reduces the resulting signal-to-noise ratio at the output. The degree of suppression of the combination channels is determined, first of all, by the frequency plan and the linearity of the amplitude characteristic of the mixer of the first frequency converter, the mirror channel – the quality of filtering the mirror frequencies in the input preselector, the neighboring channel – the selectivity of the filters of the main selection. In this article, an analytical model and the resulting graphical dependencies are developed to assess the degree of influence of compression distortions on the noise immunity of receiving multi-position quadrature-amplitude modulated signals, and the requirements for the value of the dynamic range of radio receiving systems are theoretically justified.

APPLICATION OF COMPUTER MODELING TO ASSESS THE NOISE IMMUNITY OF DIGITAL COMMUNICATION LINES WITH M-ARY FREQUENCY-SHIFT-KEYED

2020 ◽  
pp. 20-28
Author(s):  
A. V. Fomin ◽  
V. V. Voznyuk ◽  
V. M. Baranov
Keyword(s):  
Frequency Shift ◽  
Noise Immunity ◽  
Digital Communication ◽  
Communication Line ◽  
High Frequency Signal ◽  
Destructive Effect ◽  
Noise Interference ◽  
Software Model ◽  
Shift Keying ◽  
Receiver Model

The article considers the process of unintended noise interference with variable frequency and spectrum width values on a digital communication line with multi-position frequency manipulation. To conduct research in the modeling environment Matlab developed software model allows to estimate the influence of noise of various structures to receive signals from multiple frequency shift keying and obtain the dependence of the probability of bit error against signal-to-noise. The transmitter model allows you to generate a high-frequency signal manipulated by the frequency of an information message, which is represented in the work as a set of ASCIIRU-code characters. The receiver model is based on the scheme of optimal coherent reception of a frequency-manipulated signal. To improve the quality of signal reception, the transmitter and receiver models include: an interference-resistant encoder and decoder, an interleaver and deinterleaver, and an amplitude limiter. The interference model allows you to form a noise interference with a given band, with random amplitudes distributed according to the Rayleigh law, and random phases according to a uniform law in the interval [0, 2π]. Evaluation of the noise immunity of a signal receiver with multi-position frequency manipulation is performed on the basis of simulation for various noise parameters. Patterns of interference that have the most destructive effect on the receiver of signals with multi-position frequency manipulation are revealed. The protective ratio is used as an indicator of the effectiveness of radio-electronic protection, and the probability of a symbolic error (p* = 0.01) is the criterion for making a decision about the operability of the radio line.

scholarly journals Measuring Current in a Power Converter Using Fuzzy Automatic Gain Control

2021 ◽  
Vol 11 (13) ◽  
pp. 5793
Author(s):  
Bartosz Dominikowski
Keyword(s):  
High Resolution ◽  
Fuzzy Controller ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Measurement Range ◽  
Power Converter ◽  
Current Measurement ◽  
Dc Power ◽  
Programmable Gain ◽  
Electric Loads

The accuracy of current measurements can be increased by appropriate amplification of the signal to within the measurement range. Accurate current measurement is important for energy monitoring and in power converter control systems. Resistance and inductive current transducers are used to measure the major current in AC/DC power converters. The output value of the current transducer depends on the load motor, and changes across the whole measurement range. Modern current measurement circuits are equipped with operational amplifiers with constant or programmable gain. These circuits are not able to measure small input currents with high resolution. This article proposes a precise loop gain system that can be implemented with various algorithms. Computer analysis of various automatic gain control (AGC) systems proved the effectiveness of the Mamdani controller, which was implemented in an MCU (microprocessor). The proposed fuzzy controller continuously determines the value of the conversion factor. The system also enables high resolution measurements of the current emitted from small electric loads (≥1 A) when the electric motor is stationary.

Dual cavity optical automatic gain control for EDFAs

2003 ◽  
Author(s):  
M.F. Krol ◽  
Yongqian Liu ◽  
J.J. Watkins ◽  
D.W. Lambert
Keyword(s):  
Automatic Gain Control ◽  
Gain Control
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