RU2024030C1 - Modulation meter - Google Patents

Abstract

FIELD: instrumentation engineering. SUBSTANCE: modulation meter has series-connected input unit 1, first nonlinear element 2, first integrator 5, first ratio meter 8, calculator 12, and first indicator 13, as well as series-connected second nonlinear element 3, second integrator 6, second ratio meter 9, calculator 12, and second indicator 14, and also series-connected third nonlinear element 4, third integrator 7, and fourth nonlinear element 10 whose output is connected to other input of second ratio meter, and other input of first ratio meter is connected to output of fifth nonlinear element 11. EFFECT: enlarged functional capabilities. 3 dwg

Description

 The invention relates to a control and measuring technique and can be used when measuring the characteristics of signals with amplitude modulation in noisy communication channels.

 A device for measuring the modulation depth [1] is known, comprising an input unit, a linear detector, a normalization unit, a differentiation unit, a limiter-shaper, an operational amplifier, a comparator, a comparison unit, a register, a summing counter, a digital-to-analog converter, and a register with digital indication.

 The disadvantage of this device is the inability to measure the amplitude modulation coefficient in noisy communication channels.

 Closest to the proposed one is a modulometer [2], which contains an input unit, a linear detector, a low-pass filter, a ratio meter, two integrators, level locks, a module shaper, a shaper that allows you to determine the amplitude modulation coefficient by measuring the ratio of signals proportional to the amplitudes of the modulating and carrier fluctuations.

 However, this device does not allow measuring the amplitude modulation coefficient in noisy measurement channels, which limits its functionality.

 The aim of the invention is to improve the accuracy of measuring the coefficient of amplitude modulation in noisy measurement channels.

 The goal is achieved by the fact that five nonlinear elements, a third integrator, a second ratio meter, a solver and two indicators are introduced into the modulometer containing the input unit, two integrators and a ratio meter, and the output of the input unit is connected to the inputs of the first, second and third nonlinear elements the outputs of which are connected respectively to the inputs of the first, second and third integrators, the outputs of the first and second integrators are connected to the first inputs of the first and second relationship meters, the second inputs of which connected to the outputs of the fourth and fifth non-linear element whose inputs are connected to the output of the third integrator, the outputs relations gauges are connected to inputs of the decision unit, which outputs are connected to inputs of the first and second indicators.

 In FIG. 1 shows a block diagram of a modulometer.

 The modulometer contains an input unit 1, nonlinear elements 2, 3, 4, 10, 11, integrators 5, 6, 7, meters 8, 9 of relations, a solver 12 and indicators 13, 14.

;
(1)
E_c+ш(6) =

,
(2) где Е(4) = μ₄/μ₂ ² и Е(6) = μ₆/μ₂ ³; μ₂, μ₄, μ₆ - центральные моменты второго, четвертого и шестого порядков исследуемого процесса;
Е_с+ш(4) - эксцесс сигнала и шума;
Е_с(4) - эксцесс сигнала АМ, определяемый как
E_c(4) = 1,5

,
(3)
m - коэффициент модуляции;
Е_ш(4) - эксцесс шума;
Е_ш(6) - нормированный по дисперсии шестой момент сигнала и шума;
Е_с(6) - нормированный по дисперсии момент сигнала АМ, определяемый выражением
E_c(6) = 2,5

,
(4) где Е_ш(6) - нормированный по дисперсии шестой момент шума;
h² _c/ш - отношение сигнал/помеха.The operation of the modulometer is based on measuring the moment characteristics of the fourth and sixth orders of the sum of the voltages of the amplitude-modulated oscillations and noise vibrations and based on the results of measurements of the sought quantities, amplitude modulation coefficient (AM) and signal-to-noise ratio in the measurement channel. The expressions relating the coefficient of amplitude modulation m _a , the signal-to-noise ratio h ² _{c / w} and the measured moment characteristics are as follows:
E _{c + w} (4) =

;
(1)
E _{c + w} (6) =

,
(2) where E (4) = μ ₄ / μ ₂ ² and E (6) = μ ₆ / μ ₂ ³ ; μ ₂ , μ ₄ , μ ₆ - the central moments of the second, fourth and sixth orders of the investigated process;
E _{c + w} (4) - excess signal and noise;
E _with (4) is the excess of the AM signal, defined as
E _c (4) = 1.5

,
(3)
m is the modulation coefficient;
E _W (4) - excess noise;
E _W (6) is the sixth moment of the signal and noise normalized by dispersion;
E _with (6) is the dispersion-normalized moment of the AM signal, defined by the expression
E _c (6) = 2.5

,
(4) where Е _ш (6) is the sixth noise moment normalized by dispersion;
h ² _{c / w} - signal-to-noise ratio.

The noise parameters E _w (4) and E _w (6) are considered a priori known, while equations (1) and (2) are equations for two unknown m and h ² _{c / w} . For example, with Gaussian interference, E _w (4) = 3 and E _w (6) = 15. The dependency graphs (3) and (4) are shown in FIG. 2 and 3.

 The modulometer works as follows.

The signal from the measurement channel enters the input unit 1, which provides the signal level necessary for the operation of nonlinear elements. In the first non-linear element 2, the signal is converted according to the law Y ₁ = X ⁶ , in the second non-linear element the signal is converted according to the law Y ₂ = X ⁴ and in the third non-linear element - according to the law Y ₃ = X ² . The signals from the outputs of nonlinear elements 2, 3, 4 are fed to integrators 5, 6, 7, the outputs of which are signals equal to the estimates of the sixth, fourth and second moments of the process under study. The ratio meter 8 divides the estimates of the sixth moment into the third nonlinear element being raised to the third degree with the characteristic Y = X3 and the second moment estimate, while the output acts a signal equal to the estimate of the sixth moment normalized by the variance of the signal under study. The second ratio meter 9 divides the estimate of the fourth moment from the output of the integrator 6 into the square of the fourth nonlinear element 10, the estimate of the second moment, while the output acts as a signal equal to the fourth dispersion-normalized moment of the signal under study. Estimates of the sixth and fourth normalized moments from the outputs of the first and second relationship meters 8, 9 are sent to the decider 12, which implements the calculation based on a priori known E _w (4), E _w (6) and measured E _{s + w} (4) and E _{c + w} (6) is a system of two equations (1) and (2) with respect to two unknown m and h ² _{c / w} . The calculation results are displayed on the first and second indicators 13 and 14.

 It should be noted that the integrators 5, 6, 7 are made with a variable integration time T in order to change the measurement accuracy.

;

=

-

, где σ_c+ш {E(6)}, σ {E_c+ш(4)} - среднеквадратические отклонения погрешности измерения нормированных моментов, определяемые как

,

, где σ_б ² - дисперсия исходного процесса; τ_к - интервал корреляции; Т - время интегрирования.The variance of the measurement is determined by the expression
σ _m =

;

=

-

, where σ _{c + w} {E (6)}, σ {E _{c + w} (4)} are the standard deviations of the measurement error of the normalized moments, defined as

,

where σ _b ² - the variance of the original process; τ _to - correlation interval; T is the integration time.

E

(4) ;
a₂=

E

(6) +

;
b₁=

E_c(4) -

+

;

где Е_с'(4), Е_с'(6) - производные по m при m = m_изм.The coefficients a ₁ , b ₁ , a ₂ , b ₂ - are given by the expressions
a ₁ =

E

(4) ;
a ₂ =

E

(6) +

;
b ₁ =

E _c (4) -

+

;

where Е _с '(4), Е _с ' (6) are derivatives with respect to m for m = m _rev .

 The technical and economic effect is to increase the accuracy of measurements in noisy measurement channels, as well as to prevent damage due to the impossibility of such measurements.

 The proposed modulometer is fully implemented on standard elements. In particular, the solver is implemented on the KR580 microprocessor kit, fourth and sixth degree erection units are used on operational amplifiers with non-linear feedback based on transistor assemblies of the K-159 NT1 type, the remaining elements are typical.

Claims (1)

 A MODULOMETER containing an input unit, two integrators and a first ratio meter, characterized in that, in order to increase the accuracy of measuring the amplitude modulation coefficient in noisy measurement channels and expand the functionality of the module, five nonlinear elements are introduced into it, a third integrator, a second ratio meter, a solving device and two indicators, the output of the input unit being connected to the inputs of the first, second, and third nonlinear elements, the outputs of which are connected respectively to the inputs and the first, second and third integrators, the outputs of the first and second integrators are connected to the first inputs of the first and second ratio meters, the second inputs of which are connected respectively to the outputs of the fifth and fourth nonlinear elements, the inputs of which are connected to the output of the third integrator, the outputs of the ratio meters are connected respectively to the first and second input of the decisive device, the two outputs of which are connected to the inputs of the first and second indicators, respectively.

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