RU2483436C2 - Method for frequency modulation and demodulation of high-frequency signals and apparatus for realising said method - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: in order to realise said method, the apparatus for frequency modulation and demodulation of high-frequency signals has a reactive four-terminal linear element, a three-terminal nonlinear element, a low-frequency control signal source, a low-pass filter, a high-frequency signal source, a high-frequency load, a separation capacitor and a low-frequency load, wherein the reactive four-terminal linear element is in form of an overlapped T-shaped connection of four reactive two-terminal elements, parameters of which are selected from conditions of given relationships.

EFFECT: providing an operation for generating a frequency-modulated signal with a variable frequency according to the law of variation of the amplitude of the low-frequency control signal and operations for demodulating and filtering frequency-modulated signals with amplitude gain by converting the frequency-modulated signal to an amplitude-frequency-modulated signal using the high-frequency part of the demodulator with given slope ratio of the amplitude-frequency curve using one device.

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Description

The invention relates to radio communications and can be used to generate frequency-manipulated, as well as frequency-modulated signals or for their demodulation.

A known method of demodulating high-frequency frequency-modulated signals (HMS), consisting in the fact that the frequency demodulator, consisting of two parallel circuits, in a certain way connected with each other, and two nonlinear elements serves high-frequency HMS. As a result, a quasilinear section of the left slope of the amplitude-frequency characteristic (AFC) of two circuits is formed, as a result of which the HMS is converted into an amplitude-frequency-modulated signal (AHMS). In this case, the amplitude of the frequency response varies according to the law of frequency change of the input frequency response. This signal then undergoes the same transformations as in the amplitude demodulator [Non-linear radio engineering devices / edited by N. L. Teplov. M .: Military Publishing. 1982, p.182-198, S. Baskakov Radio circuits and signals. M.: Higher School, 1988, pp. 286-292]. This means that on nonlinear elements the frequency response spectrum is destroyed (decomposed) into low-frequency and high-frequency components. Then, using the low-pass filter, a low-frequency component is extracted, the amplitude of which changes according to the law of frequency change of the input HMS. Then, with the help of the separation capacitance included in the longitudinal chain (sequentially), the constant component that occurs on the nonlinear elements as a result of interaction with the AFM is eliminated. After that, low-frequency vibrations containing useful information are allocated to the low-frequency load. This is a demodulation mode. If a harmonic signal is used as the input high-frequency signal, and a low-frequency control signal is supplied to nonlinear elements, then in the general case a high-frequency signal with variable amplitude, frequency and phase will be generated at the output. This is a modulation mode.

The disadvantage of this method and device for its implementation is that in the demodulation mode for highlighting a low-frequency signal, the amplitude of which changes in accordance with the law of the phase change of the high-frequency, the left slope of the frequency response is formed only by choosing the parameters of two loops. The parameters of reactive and resistive linear elements of the rest of the frequency demodulator circuit and the frequency characteristics of nonlinear elements are not taken into account when forming a given left slope of the frequency response. Another disadvantage is the inability to correct the amplitude modulation coefficient of the AMF, which when passing through the resonant circuits leads to a decrease in this characteristic, that is, to the well-known phenomenon of partial amplitude demodulation of the AMF or to a decrease in noise immunity. The third drawback is that in the modulation mode, the amplitude, frequency and phase of the generated high-frequency signal change according to unknown laws, since the circuit is synthesized only by the criterion of ensuring the demodulation operation. However, in the case of frequency modulation, it is necessary to create an FMC with a constant amplitude, the frequency of which changes according to the law of the amplitude of the control signal. The disadvantages should also include the lack of filtering of the input signal in the frequency demodulation mode due to the formation of the necessary form of frequency response.

The closest in technical essence and the achieved result (prototype) is the method of demodulating an FMC, which consists in the fact that for the demodulation of an FMC a frequency detector is used, consisting of a cascade-connected amplitude limiter, a converter of the FMC in the AFCM in the form of a parallel oscillatory circuit and a conventional amplitude demodulator with one nonlinear element. Further, the process of isolating the low-frequency component is carried out in the same way as described above. If the frequency of the carrier signal of the ChMS is located on the left slope of the frequency response of the circuit, the amplitude of the ChMS varies according to the law of changing the frequency of the input ChMS [Baskakov S.I. Radio circuits and signals. M.: Higher School, 1988, pp. 286-292]. If necessary, between the source of modulated signals and the nonlinear element or between the nonlinear element and the load include a reactive or resistive four-terminal network for matching and additional signal and interference selection. As a result, at the output of the device, we have a low-frequency oscillation, the amplitude of which changes according to the law of variation of the envelope of the input high-frequency phase-modulated oscillation. This is a demodulation mode. If a harmonic signal is used as the input high-frequency signal, and a low-frequency control signal is supplied to the nonlinear element, then in the general case a high-frequency signal with variable amplitude, frequency and phase will be generated at the output. This is a modulation mode.

The disadvantage of the method and device for its implementation is that in the demodulation mode after converting the HMS to AFM, the amplitude modulation coefficient of the AMF is not controlled and, as a rule, is insignificant in value, which impairs noise immunity [S. Baskakov Radio circuits and signals. M.: Higher School, 1988, pp. 286-292. Gonorovsky I.S. Radio circuits and signals. M .: Radio and communications, 1986, p. 247-252]. This disadvantage is associated with the presence of an oscillatory circuit for converting an FMC to an AMF, the parameters of which are not determined from the conditions for the formation of a slope of the frequency response with a given slope. The third drawback is that the classical theory of radio circuits assumes that the nonlinear element is purely resistive and inertia-free, and therefore does not react in any way to changes in the frequency and phase of the input signal, but only to changes in amplitude. Meanwhile, the daily experience of designers shows that nonlinear elements have internal capacitances and inductances, which have a significant impact on the formation of the dependence of their conductivity (resistance or elements of the matrix of conductivities or resistances) on frequency. This is especially significant with increasing frequency, which is currently mainly sought by designers of new systems and means of radio communications. The main disadvantage should be considered that in the modulation mode, the amplitude, frequency and phase of the generated high-frequency signal change according to unknown laws, since the circuit is synthesized only by the criterion of ensuring the operation of demodulation. This does not allow to reduce the range of radio devices and to unify frequency modulators and demodulators in the interests of production. The disadvantages should also include the lack of filtering of the input signal in the frequency demodulation mode due to the formation of the necessary form of frequency response.

Thus, the main disadvantages of all existing methods and devices for frequency modulation and demodulation coincide and consist in the lack of the ability to effectively combine these functions with one device.

The technical result of the invention is the provision of the operation of generating an emergency frequency modulation according to the law of changing the amplitude of the control (information) low-frequency signal and the operation of demodulating and filtering the emergency frequency amplification due to the conversion of the emergency frequency signal into the frequency response using the high-frequency part of the demodulator with a given slope of the frequency response at a given frequency deviation ChMS in modulation mode and a given coefficient of amplitude modulation. ChMS in demodulation mode at high frequency load using one troystva that enhances the noise immunity of the receiver reduces the range of frequency and unifies modulators and demodulators. In the future, in the modulation mode, by a high-frequency signal we mean a signal that occurs at the moment of switching on a constant voltage source (amplitude jump), and by a low-frequency signal as a control or information signal. In the demodulation mode, by a high-frequency signal we mean an HMF, and by a low-frequency signal we mean the envelope of the formed AFM as a result of the interaction of the variable frequency of the HMF and the quasilinear left slope of the frequency response of the entire frequency modulation and demodulation device. The ability to change the option to turn on a nonlinear element is an additional way to increase the quasilinear sections of an AFC elephant in the demodulation mode and the modulation characteristic in the modulation mode.

1. The specified result is achieved by the fact that in the method of frequency modulation and demodulation of high-frequency signals, consisting in the interaction of high-frequency and low-frequency signals with a frequency modulation and demodulation device made of a reactive four-terminal device, non-linear element, low-pass filter, separation capacitance and low-frequency load, in demodulation mode, the high-frequency signal is converted into an amplitude-frequency-modulated signal by applying a high-frequency signal to the left slope of the frequency response frequency modulation and demodulation devices, using a nonlinear element, destroy the spectrum of the amplitude-frequency-modulated signal into high-frequency and low-frequency components, use the low-pass filter to isolate the low-frequency component, eliminate the DC component using a dividing capacitance, apply an informational low-frequency signal, amplitude to the low-frequency load which varies according to the law of frequency variation of the input high-frequency signal, in the modulation mode a nonlinear element under they switch on to the source of the information low-frequency signal, the frequency of the high-frequency signal changes with the amplitude of the information low-frequency signal, in addition to the low-pass filter, a high-frequency load is introduced into the transverse circuit, a three-pole non-linear element is selected as a non-linear element and it is connected between the four-terminal and high-frequency load according to the scheme with a common one of the three electrodes in the modulation mode form a frequency-modulated high-frequency signal with a given the law of frequency change, corresponding to the law of change of the amplitude of the information low-frequency signal, by ensuring the conditions of phase balance and amplitude balance on a given range of changes in the high frequency and the corresponding range of changes in the amplitude of the information low-frequency signal, remove the frequency-modulated signal from the high-frequency load, in the demodulation mode, the frequency modulated signal into an amplitude-frequency modulated signal, its amplification and filtering is carried out by the formation of a quasilinear left slope and a given shape of the amplitude-frequency characteristic of the modulation and demodulation device due to the implementation of the necessary frequency dependences of the parameters of the four-terminal network using the following mathematical expressions:

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- заданные зависимости действительных и мнимых составляющих элементов матрицы сопротивлений трехполюсного нелинейного элемента от частоты и амплитуды низкочастотного управляющего сигнала в режиме модуляции; остальные величины имеют смысл промежуточных обозначений в интересах упрощения математических выражений.α, β, γ are the optimal frequency dependences of the relations of the corresponding elements of the classical transmission matrix of the quadrupole a, b, c, d; d is the optimal frequency dependence of one of the elements of the classical transmission matrix; m _∂ is the optimal dependence of the transfer function module of the high-frequency part of the frequency modulation and demodulation device on frequency in the demodulation mode, satisfying the condition of physical realizability; φ _∂ is the specified linearly decreasing phase dependence of the transfer function of the high-frequency part of the frequency modulation and demodulation device in frequency in the demodulation mode, satisfying the condition of ensuring the linearity of the left slope of the frequency response; r ₀ , x ₀ - specified frequency dependences of the real and imaginary components of the resistance of the source of the frequency-modulated signal in the demodulation mode, equal to the frequency dependences of the real and imaginary components of the resistance of the imaginary source of high-frequency signals that occur when the DC source is turned on, in the modulation mode; r _n , x _n - given frequency dependences of the real and imaginary components of the resistance of the high-frequency load in both modes; r ₁₁ , r ₁₂ , r ₂₁ , r ₂₂ , x _11T , x _12T , x _21T , x _22T - given dependences of the real and imaginary components of the resistance matrix of a three-pole nonlinear element on the frequency and amplitude of the amplitude-frequency-modulated signal in demodulation mode;

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- the given dependences of the real and imaginary component elements of the resistance matrix of a three-pole nonlinear element on the frequency and amplitude of the low-frequency control signal in modulation mode; the remaining quantities have the meaning of intermediate notation in the interests of simplifying mathematical expressions.

2. This result is achieved by the fact that in the device of frequency modulation and demodulation of high-frequency signals connected between the source of high-frequency signals and the low-frequency load and consisting of a linear reactive four-terminal device, a nonlinear element connected in modulation mode to the source of the low-frequency control signal, low-pass filter and a separation signal capacitance, in addition to the low-pass filter, a high-frequency load is introduced into the transverse circuit, as a nonlinear element Use This Criterion tripolar nonlinear element which is connected between the quadripole and high-load the circuit with a common one of the three electrodes quadripole formed as the overlapped T-fitting of the four reactive two-terminal networks with resistances _{x 1n, x 2n, x 3n} , x 4n , respectively, the second third and fourth two-pole formed of two successive loops connected in parallel with the parameters _{L 1k, C 1k, L 2k} , C 2k parameters of these two-poles selected from the conditions for the formation of a quasi-linear slope and the form of the amplitude-frequency characteristic in the frequency demodulation mode and conditions to balance the amplitude and phase balance within a predetermined range of frequency change, and a predetermined range of the low frequency control in the frequency modulation mode in signal amplitude by using certain mathematical expressions:

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- заданные значения действительных и мнимых составляющих элементов матрицы сопротивлений трехполюсного нелинейного элемента на заданных четырех частотах и четырех значениях амплитуды низкочастотного управляющего сигнала в режиме модуляции; k=2, 3, 4 - номера второго, третьего и четвертого двухполюсников перекрытого Т-образного соединения четырех реактивных двухполюсников; x_1n - заданные значения сопротивлений первого двухполюсника на заданных четырех частотах; остальные величины имеют смысл промежуточных обозначений в интересах упрощения математических выражений.α, β, γ are the optimal ratios of the corresponding elements of the classical transmission matrix of the quadrupole a, b, c, d at given four frequencies ω _n = 2πf; n = 1, 2, 3, 4 - numbers of the given frequencies; d are the optimal values of one of the elements of the classical transmission matrix at given four frequencies; m _∂n are the optimal values of the transfer function modulus of the high-frequency part of the frequency modulation and demodulation device at four predetermined frequencies in the demodulation mode, satisfying the condition of physical realizability; φ _∂n are the specified linearly decreasing phase values of the transfer function of the high-frequency part of the frequency modulation and demodulation device at the given four frequencies in the demodulation mode, satisfying the condition of ensuring the linearity of the left slope of the frequency response; r _0n , x _0n - set values of the real and imaginary components of the resistance of the source of the frequency-modulated signal in the demodulation mode, equal to the values of the real and imaginary components of the resistance of the imaginary source of high-frequency signals that occur when the DC source is turned on, in the modulation mode at the specified four frequencies; r _nn , x _nn - set values of the real and imaginary components of the resistance of the high-frequency load in both modes at the specified four frequencies; r _11n , r _12n , r _21n , r _22n , x _11Tn , x _12Tn , x _21Tn , x _22Tn are the values of the real and imaginary components of the resistance matrix of a three-pole nonlinear element at the given four frequencies and four amplitude values of the amplitude-frequency-modulated signal in demodulation mode;

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- the set values of the real and imaginary component elements of the resistance matrix of a three-pole nonlinear element at specified four frequencies and four values of the amplitude of the low-frequency control signal in modulation mode; k = 2, 3, 4 — numbers of the second, third, and fourth two-terminal devices of the overlapped T-shaped connection of four reactive two-terminal devices; x _1n - set resistance values of the first two-terminal at given four frequencies; the remaining quantities have the meaning of intermediate notation in the interests of simplifying mathematical expressions.

Figure 1 shows a structural diagram of a device for frequency modulation and demodulation of high-frequency signals (prototype) that implements the prototype method.

Figure 2 shows the structural diagram of the proposed device frequency modulation and demodulation according to claim 2, which implements the proposed prototype method according to claim 1.

Figure 3 shows the structural diagram of the four-terminal network (matching filtering device (SFU)) of the proposed device frequency modulation and demodulation according to claim 2, shown in figure 2.

Figure 4 shows a schematic diagram of the first, second and fourth two-terminal, forming a four-terminal (figure 3) of the proposed device frequency modulation and demodulation according to claim 2, shown in figure 2.

The prototype device (Fig. 1) in demodulation mode contains a source of 1 high-frequency signals (HMS) with a resistance of z ₀ = r ₀ + jx ₀ , a four-terminal 2, a two-pole (two-electrode) non-linear element 3, a low-pass filter 4 on the elements R, C , dividing capacity 5 on the element With _p and low-frequency load 6 on the elements R _n , With _n In modulation mode, the source of the control (primary or informational) low-frequency signal (not shown in Fig. 1) is connected to a nonlinear element.

The principle of operation of the device frequency modulation and demodulation of high-frequency signals (prototype) is as follows.

In demodulation mode, a frequency-modulated (high-frequency) signal from source 1 is fed to the left slope of the frequency response of the four-terminal reactive 2, which is a parallel oscillatory circuit and connected between the source of the ChMS-1 and the non-linear element - 3, thereby converting the HMS to AFC using non-linear element 3 destroy the spectrum of the frequency response on high-frequency and low-frequency components. The latter are allocated using a low-pass filter 4 and enter the low-frequency load 6. The separation capacitance 5 eliminates the constant component. As a result, at the output of the device, we have a low-frequency oscillation, the amplitude of which changes according to the law of changing the frequency of the input high-frequency frequency-modulated oscillation.

In the modulation mode, a change in the capacitance of the varicap circuit under the action of the control signal of the source leads to an additional change in the amplitude, frequency and phase of the input HMS in the general case according to an uncontrolled law. The remaining disadvantages of the method and device for its implementation (prototype) are described above.

The high-frequency part of the structural diagram of the generalized proposed modulation and demodulation device (up to the low-pass filter) according to claim 2 (Fig. 2) consists of a cascade-connected source of high-frequency signals 1, a reactive four-terminal 2, a three-pole nonlinear element 3, connected according to a common one of three electrodes, and a high-frequency load 7. The low-frequency part of the structural circuit contains a low-pass filter 4, a separation capacitor 5 and a low-frequency load 6. In the modulation mode, the ChMS-1 source is turned off, ynomu source control element connected baseband signal and a constant voltage source (not shown in Figure 2). The reactive four-terminal 2 is made in the form of an overlapped T-shaped connection of four reactive two-terminal (Fig. 3) with resistances x ₁ - 8, x ₂ - 9, x ₃ - 10, x ₄ - 11, respectively. The second, third and fourth two-terminal circuits are formed of two parallel connected series circuits with parameters L _1k , C _1k , L _2k , C _2k (Fig. 4). The parameters of these two-terminal devices are selected from the conditions for the formation of a quasilinear slope and the given shape of the amplitude-frequency characteristic in the frequency demodulation mode and the conditions for ensuring the balance of amplitudes and phases in a given frequency range and a given range of the amplitude of the low-frequency control signal in the frequency modulation mode using certain mathematical expressions.

The principle of operation of this device is that in the demodulation mode when applying the HMS from source 1 with resistance z _0, as a result of a special choice of the values of the two-terminal elements, the left slope of the frequency response and the given shape of the frequency response of the high-frequency part will be formed. This provides a given coefficient of amplitude modulation of the AMF, amplification and filtering, which increases the noise immunity of the receiver. At the same time, the frequency response spectrum is destroyed using a nonlinear element 3 connected between the signal source and the four-terminal network. The low-frequency oscillation is extracted using the low-pass filter - 4. As a result, the low-frequency oscillation, the amplitude of which changes according to the law of the frequency of the input HMS, is allocated to the low-frequency load 6.

In the modulation mode at a high-frequency load, an FMR is formed with a given law of frequency change, corresponding to the law of change in the amplitude of the low-frequency signal.

Principle of operation. When you turn on the DC voltage source (not shown in FIG. 2), due to the abrupt change in the amplitude, oscillations arise in the entire circuit, the spectrum of which occupies the entire frequency radio frequency range. The amplitudes of these oscillations decay quickly. However, due to the presence of feedback, the real part of the resistance matrix element z ₂₁ or z _{12 of the} three-pole nonlinear element (transistor) becomes negative. This, taking into account the synthesis of the four-terminal - 3, according to a given criterion, compensates for losses in the entire circuit. The amplitude of the oscillation with a given frequency is amplified to a certain level and then limited. The synthesis of the four-terminal - 3 was carried out according to the criterion for the coincidence of the real frequency dependences of the resistances of the second, third, and fourth two-terminal at four frequencies with optimal characteristics, providing a change in the frequency of the generated signal according to the law corresponding to the law of variation of the amplitude of the control signal.

Due to this, the oscillation with a given carrier frequency is amplified until the amplitude of this oscillation increases to the limiting section of the current-voltage characteristic of the passage. There is a stationary mode. In this mode, a change in the real and imaginary components of the resistance matrix of a three-pole nonlinear element - 1 under the action of a control signal leads to a change in the frequency of the generated signal according to the law of change in the amplitude of the low-frequency control signal. Formed ChMS removed from high-frequency load.

Let us prove the feasibility of implementing these properties.

,Let the frequency-modulated oscillation act on the input of the modulator / demodulator in demodulation mode

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where U _n , ω _n - the amplitude and frequency of the carrier high-frequency oscillations; Δω is the deviation (maximum deviation) of the frequency; Ω is the frequency of the primary information low-frequency signal. ChMS frequency changes according to the law of the derivative phase

If the limits of the frequency change of the frequency-modulated signal (HMS) do not go beyond the boundaries of the left quasilinear slope of the amplitude-frequency characteristic (AFC) of the demodulator, then the HMS will be converted to the amplitude-frequency-modulated signal (AHMS). In this case, the amplitude of the AFM will vary according to the law (cos (Ωt)), that is, according to the law of changing the frequency of the input HMS. Further, the signal conversion occurs in the same way as in the amplitude demodulator.

Thus, the main task in the implementation of frequency demodulation is to ensure the conditions under which a quasilinear portion of the left slope of the AFC of the demodulator is formed in a given frequency band, the boundaries of which coincide or are comparable with the extreme values of the frequencies of the frequency range of the FSM.

The input modulated high-frequency signal S _in and converted using the high-frequency part of the demodulator (before the low-pass filter) the high-frequency signal S _o are connected as follows: S _o = S ₂₁ S _in , where the input and output signals mean the input and output voltages; S ₂₁ - gear ratio.

Let the transmission coefficient of the high-frequency part of the frequency modulator and demodulator in demodulation mode is set as follows:

where m _∂ , φ _∂ are the given dependences of the modulus and phase of the transmission coefficient on frequency.

Let the dependences of the resistance of the signal source Z ₀ = r _o + jx ₀ , the load Z _n = r _n + jx _n and the elements of the resistance matrix of a three-pole nonlinear element z ₁₁ = r ₁₁ + ix _11T , z ₁₂ = r ₁₂ + ix _12T , z ₂₁ = r ₂₁ + ix _21T ; z ₂₂ = r ₂₂ + ix _22T versus frequency (the argument ω = 2πf is omitted for simplicity). In addition, the elements of the resistance matrix of a three-pole non-linear element depend on the amplitude of the generated AFMS. Elements r ₂₁ or r ₁₂ have a negative sign [Batushev V.A., Veniaminov V.N., Miroshnichenko A.I. Electronic elements of military communications equipment. M .: Military Publishing House, 1984. P.424], therefore, under certain conditions, it is possible to increase the amplitude of the input emergency. The index T is introduced in the interest of distinguishing the corresponding constituent elements of the resistance matrix of a three-pole non-linear element in the demodulation mode from the elements of the known resistance matrix of a reactive four-terminal device and from the elements of the resistance matrix of a non-linear element in the modulation mode.

It is required to determine the frequency characteristics of the four-terminal and two-terminal, from which the four-terminal is formed, as well as the minimum number of elements and parameter values of the two-terminal, for which the given frequency dependences of the modules m _∂ and phases φ _{∂ of} the transmission coefficient (1) would be provided.

Let the quadrupole contain only reactive elements. Thus, taking into account the reciprocity condition (x ₁₂ = -x ₂₁ ), the SFU can be characterized by a resistance matrix

and the corresponding classical transfer matrix:

where | x | = -x ₁₁ x ₂₂ -x ₂₁ ² is the determinant of matrix (2).

A three-pole non-linear element is characterized by a resistance matrix and its corresponding classical transmission matrix:

where | z | = z ₁₁ z ₂₂ -z ₂₁ z ₁₂ is the determinant of the resistance matrix (4).

We multiply the transfer matrices (3) and (4) and taking into account the normalization conditions [Feldstein A.L., Yavich L.R. Microwave four-terminal and eight-terminal synthesis. M .: Communication, 1971. p. 34-36] we obtain the expression for the normalized transmission matrix of the high-frequency part of the entire device:

Using the well-known relations between the elements of the classical transfer matrix and the elements of the scattering matrix [Feldstein A.L., Yavich L.R. Microwave four-terminal and eight-terminal synthesis. M .: Communication, 1971. p. 39], taking into account (5), we obtain the expression for the transmission coefficient of the high-frequency part of the demodulator:

The radical expression in (6) can be represented as a complex number a ₁ + jb ₁ ,

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;Where

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x = r _o r _n -x _o x _n ; y = r _o x _n + x _o r _n

последнее выражение изменяется а₁=r_н; b₁=x_н.After denormalizing the transmission coefficient (6) by multiplying by

the last expression changes a ₁ = r _n ; b ₁ = x _n

.The denormalized transmission coefficient is associated with a physically feasible transfer function as follows

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To obtain the relationships between the elements of the resistance matrix that are optimal according to the criterion for ensuring the given frequency dependences of the modules and phases of the transfer function of the high-frequency part of the demodulator, we substitute (6) in (1) and after separating the real and imaginary parts from each other, we obtain a system of two equations:

where A = -xsinφ + rcosφ, B = x _22n cosφ + r _22n sinφ, C = r _22n cosφ-x _22n sinφ, H = xcosφ + rsinφ.

The solution to system (7) has the form of two relationships between the elements of the SFU resistance matrix or the approximating functions of the frequency dependences of these elements according to criterion (1):

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;Where

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A ₀ = r _a r _2н∂ + x _a x _2н∂ ; B ₀ = x _a r _2н∂ -r _a x _2н∂ ; R ₀ = r _∂ r _2n∂ + x _∂ x _2n∂ ;

r _∂ = r ₁₁ r ₂₂ -x _11T x _22T -r ₁₂ r ₂₁ + x _12T x _21T -r _11T r _n + x _11T x _n ; r _2n∂ = -r ₂₂ + r _n ; r _a = r ₂₁ a ₁ -x _21T b ₁ ;

x _∂ = r ₁₁ x _22T + x _11T r ₂₂ -x _12T r ₂₁ -r ₁₂ x _21T -r ₁₁ x _n -x _11T r _n ; x _2n∂ = -x _22T + x _n ; x _a = r ₂₁ b ₁ + x _21T a ₁ .

In the interest of further reasoning, by using the known relations between the elements of the resistance matrix and the elements of the classical transmission matrix, we write the relationships (8) in terms of the elements of the classical transmission matrix (the order of the equations obtained in the future decreases):

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;Where

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a, b, c, d - elements of the classical transmission matrix.

Since the information is enclosed in the frequency response envelope, the frequency dependence of the modulus m _{∂ of the} transfer function on the left slope of the frequency response must be selected linear. In addition, the frequency dependence of the modulus m _∂ must satisfy the condition of physical realizability (19). The frequency dependence of the phase φ _{in the} transfer function can be chosen arbitrarily or on the basis of any other physical considerations. In the present invention, it is selected from the condition of ensuring the linearity of the left slope of the frequency response. To do this, it must be linearly decreasing and changing sign from positive to negative at a frequency equal to the maximum frequency of the emergency response. At this frequency, the value of m _∂ will be maximum.

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от частоты в заданном диапазоне изменения частоты генерируемого сигнала, соответствующие закону изменения амплитуды низкочастотного управляющего сигнала. Таким образом, каждому заданному значению амплитуды низкочастотного сигнала соответствуют определенные значения элементов матрицы сопротивлений трехполюсного нелинейного элемента

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,

,

соответствующие определенному значению частоты генерируемого сигнала на заданном диапазоне ее изменения. Для простоты записи аргументы ω=2πf (круговая частота) и U, I (напряжение или ток амплитуды низкочастотного сигнала) опущены. Кроме того, элементы матрицы сопротивлений трехполюсного нелинейного элемента зависят от амплитуды низкочастотного управляющего сигнала. Элементы

или

имеют отрицательный знак [Батушев В.А., Вениаминов В.Н., Мирошниченко А.И. Электронные элементы военной техники связи. М.: Воениздат, 1984. С.424], поэтому при определенных условиях можно генерировать собственный высокочастотный сигнал. Таким образом, известна матрица сопротивлений транзистора:Suppose, in addition to the above initial data in modulation mode, that the dependences of the real and imaginary components of the resistance matrix of a three-pole nonlinear element are known

,

,

,

,

,

,

,

from the frequency in a given range of changes in the frequency of the generated signal, corresponding to the law of change in the amplitude of the low-frequency control signal. Thus, each given value of the amplitude of the low-frequency signal corresponds to certain values of the elements of the resistance matrix of a three-pole nonlinear element

,

,

,

,

,

,

,

corresponding to a certain value of the frequency of the generated signal over a given range of its change. For simplicity of writing, the arguments ω = 2πf (circular frequency) and U, I (voltage or current amplitude of the low-frequency signal) are omitted. In addition, the elements of the resistance matrix of a three-pole nonlinear element depend on the amplitude of the low-frequency control signal. Items

or

have a negative sign [Batushev V.A., Veniaminov V.N., Miroshnichenko A.I. Electronic elements of military communications equipment. M .: Military Publishing House, 1984. P.424], therefore, under certain conditions, you can generate your own high-frequency signal. Thus, the transistor resistance matrix is known:

and the corresponding classical transfer matrix:

Elements of the resistance matrix are:

;

;

;

;

;

;

;

;

;

;

The sign * is introduced in the interest of distinguishing the corresponding constituent elements of the resistance matrix of a three-pole nonlinear element in the modulation mode from the elements of the known resistance matrix of the reactive four-pole network and from the elements of the resistance matrix of the nonlinear element in the demodulation mode.

Multiply matrices (11) and (2). Taking into account the normalization conditions, we obtain the general normalized classical transmission matrix of the entire high-frequency part of the frequency modulation and demodulation:

Using the well-known relations between the elements of the classical transfer matrix and the elements of the scattering matrix [Feldstein A.L., Yavich L.R. Microwave four-terminal and eight-terminal synthesis. M .: Communication, 1971. p. 39], taking into account (5), we obtain the expression for the transmission coefficient of the high-frequency part of the modulator:

The radical expression in (6) can be represented as a complex number a ₁ + jb ₁ ,

;

;Where

;

;

x = r _o r _n -x _o x _n ; y = r _o x _n + x _o r _n

последнее выражение изменяется а₁=r_н; b₁=x_н.After denormalizing the transmission coefficient (6) by multiplying by

the last expression changes a ₁ = r _n ; b ₁ = x _n

.The denormalized transmission coefficient is associated with a physically feasible transfer function as follows

.

The condition for ensuring the stationary generation mode (the condition of the balance of amplitudes and phase balance) corresponds to the equality to zero of the denominator of the transmission coefficient (3). After dividing the complex equation formed from this equality into real and imaginary parts, we get a system of two equations:

;

;

;

;

;

;

;

;

The solution to system (14) has the form of two relationships between the elements of the SFU resistance matrix or those that are optimal according to the criterion of providing a stationary generation regime by approximating functions of the frequency dependences of these elements:

;

;

Where

;

;

In the interest of further reasoning, by using the known relations between the elements of the resistance matrix and the elements of the classical transmission matrix, we write the relationships (14) in terms of the elements of the classical transmission matrix (the order of the equations obtained in the future decreases):

In order for the same device to perform the functions of a frequency demodulator and a frequency modulator, it is necessary that the optimal frequency approximating functions (9) and (16) be pairwise equal (the solutions obtained for both modes are crosslinked). These equalities imply restrictions on the frequency characteristics of two more elements of the classical transmission matrix:

where A = D _M -D _∂ ; B = E _m -E _∂ ; D = F _m -F _∂ ;

- качество устройства модуляции и демодуляции, характеризующее меру различия действительных и мнимых составляющих элементов матрицы сопротивлений трехполюсного нелинейного элемента в режимах модуляции и демодуляции с учетом действительной и мнимой составляющих сопротивления высокочастотной нагрузки. Оптимальные частотные характеристики (9), (17) или (16), (17) должны удовлетворять условиям физической реализуемости (условию взаимности четырехполюсника):

- the quality of the modulation and demodulation device, which characterizes the measure of difference between the real and imaginary components of the resistance matrix of a three-pole nonlinear element in modulation and demodulation modes, taking into account the real and imaginary components of the resistance of the high-frequency load. The optimal frequency characteristics (9), (17) or (16), (17) must satisfy the conditions of physical realizability (the reciprocity condition of the four-terminal network):

Condition (18) allows you to determine the optimal amplitude-frequency characteristic of the high-frequency part of the proposed device in demodulation mode:

Three independent optimal frequency characteristics of the elements of the classical transmission matrix from (9), (17) or (16), (17) for the elements α, β, γ (the element d is dependent on (18)) means that the reactive four-terminal network (SFU ) must contain at least three independent two-terminal networks, the frequency dependences of the resistances of which must be determined based on the use of (9), (17) or (16), (17) for elements α, β, γ. For this, it is necessary to choose a typical SFU scheme, determine the elements α, β, γ, expressed through the resistance of reactive two-terminal devices, and substitute them in (9), (17) or (16), (17). The system of three equations thus formed must be solved with respect to the resistances of the selected three two-terminal networks. The resulting mathematical expressions will be the optimal frequency dependences (approximating functions) of the resistances of these two-terminal circuits according to the criterion of providing a given shape of the frequency response in demodulation mode and providing conditions for amplitude balance and phase balance in modulation mode in a given frequency band. If the number of two-terminal devices in the Siberian Federal University is more than three, then the frequency characteristics of the remaining two-terminal devices can be chosen arbitrarily or from any other physical considerations, for example, from conditions of physical realizability.

In accordance with the above algorithm, the optimal frequency dependences of the resistances of the second, third and fourth two-terminal circuits of the selected SFU circuit in the form of an overlapped T-shaped connection of four reactive two-terminal circuits were obtained (Fig. 3):

,

,

,

,

,

,

,

и другие.where n = 1,2 ... are the numbers of interpolation frequencies introduced in the interests of realizing the obtained approximations (20). Resistances x _{1n of the} first two-terminal can be chosen arbitrarily or on the basis of any other physical considerations. The index n must also be included in the remaining used initial and calculated quantities r _0n , x _0n , r _нn , x _нn , m _∂n , φ _∂n , r _11n , r _12n , r _21n , r _22n , x _11Tn , x _12Tn , x _21Tn , x _22Tn ,

,

,

,

,

,

,

,

and others.

To implement the optimal approximations (20) by interpolation, it is necessary to form the second, third, and fourth two-terminal networks with resistances x _2n , x _3n , x _4n from at least N (the number of interpolation frequencies) of the reactive elements, find expressions for their resistances, equate their optimal values resistances of two-terminal networks at given frequencies, determined by formulas (20), and solve the system of N equations thus formed that relates to N selected parameters of reactive elements. The values of the parameters of the remaining elements can be chosen arbitrarily or on the basis of any other physical considerations, for example, from the condition of physical realizability. Let each of the two-terminal circuits with resistances x _2n , x _3n , x _{4n be} formed from two parallel-connected sequential circuits L _1k , C _1k , L _2k , C _2k (Fig. 4) (k = 2, 3, 4 - the number of the two-terminal circuit (Fig. .3)). For N = 4, we compose three systems of four equations:

The implementation of optimal approximations of the frequency characteristics of the four-terminal network in the form of an overlapped T-link (20) using (22) in the frequency modulation mode provides an increase in the frequency range of the generated signal (frequency deviation), since it implements the condition of amplitude balance and phase balance at four frequencies of a given range changes in frequency and the corresponding four corresponding values of the amplitude of the low-frequency control signal. This allows for a reasonable choice of the positions of the given frequencies relative to each other ω ₁ -ω ₂ , ω ₁ -ω ₃ , ω ₁ -ω ₄ , ω ₂ -ω _3, ω ₂ -ω ₄ , ω ₃ -ω ₄ to expand the linear section of the modulation characteristics. In the frequency demodulation mode, this allows you to form a given shape of the frequency response with a quasilinear portion of the left slope of the frequency response. Varying the values of the free parameters of the proposed device can further increase the quasilinear sections of the slope of the frequency response in demodulation mode and modulation characteristics in modulation mode. However, this task is beyond the scope of the invention.

The proposed technical solutions are new, since the method and device of frequency modulation and demodulation of high-frequency signals that provide the formation of a quasilinear frequency response slope in a given frequency range with a given frequency response form are unknown from public information, which allows the conversion of HMS to AHMS with a given amplitude modulation coefficient of AHMS, amplification filtering in demodulation mode and the formation of a quasilinear frequency modulation characteristic in a given range of amp the tones of the control signal in modulation mode using a multifunctional device consisting of a three-pole nonlinear element connected to a source of a low-frequency control signal and turned on according to a circuit with a common one of three electrodes between the output of the reactive four-terminal and a high-frequency load connected in front of the low-pass filter in the transverse circuit, dividing capacitance and low-frequency load, and the four-terminal is made in the form of an overlapped T-link of four reactive two -pole, second, third and fourth of which are formed of two parallel circuits connected in series, the parameters of which are defined by respective mathematical expressions.

The proposed technical solutions have an inventive step, since it does not explicitly follow from the published scientific data and the known technical solutions that the stated above sequence of operations allows using one radio device to carry out frequency demodulation and modulation of high-frequency signals with a quasilinear portion of the left slope of the frequency response and a given frequency response in the interests of the conversion of HMS to AFMC, amplification and filtering in demodulation mode and a quasilinear frequency modulation characteristic a characteristic for the formation of an FMC in modulation mode due to the implementation of the conditions of the balance of amplitudes and phase balance in a given range of frequency changes and the range of changes in the amplitude of the control signal.

The proposed technical solutions are practically applicable, since semiconductor three-electrode (three-pole) nonlinear elements (transistors), inductances and capacitances formed in the claimed circuit of reactive two-terminal circuits included in the claimed four-terminal circuit can be used for their implementation. The values of the resistance of the two-terminal x ₂ , x ₃ , x ₄ , inductances and capacitances can be determined using mathematical expressions given in the claims.

The technical and economic efficiency of the proposed device is to provide filtering, frequency modulation, frequency demodulation and amplification of high-frequency signals using a single device, which leads to a decrease in the range of radio devices and their unification in the interests of production.

Claims (2)

1. The method of frequency modulation and demodulation of high-frequency signals, consisting in the interaction of high-frequency and low-frequency signals with a frequency modulation and demodulation device made of a four-port reactive device, a nonlinear element, a low-pass filter, a separation capacitance, and a low-frequency load; in the demodulation mode, the high-frequency signal is converted into amplitude -frequency-modulated signal by applying a high-frequency signal to the left slope of the frequency response of a frequency modulation and demodulation device and, using a non-linear element, the spectrum of the amplitude-frequency-modulated signal is destroyed into high-frequency and low-frequency components, a low-frequency component is isolated using a low-pass filter, a constant component is eliminated with a dividing capacitance, an informational low-frequency signal is fed to the low-frequency load, the amplitude of which changes according to the law changes in the frequency of the input high-frequency signal; in the modulation mode, the nonlinear element is connected to the source of information low frequency signal, the frequency of the high-frequency signal changes with the amplitude of the information low-frequency signal, characterized in that a high-frequency load is introduced into the transverse circuit in front of the low-pass filter, a three-pole non-linear element is selected as a non-linear element and it is connected between the four-terminal and high-frequency load according to the scheme with a common one of three electrodes, in the modulation mode form a frequency-modulated high-frequency signal with a given law of frequency change, respectively In accordance with the law of changing the amplitude of the information low-frequency signal, by ensuring the conditions of phase balance and amplitude balance on a given range of changes in the high frequency and the corresponding range of changing the amplitude of the information low-frequency signal, the frequency-modulated signal is removed from the high-frequency load; -frequency-modulated signal, its amplification and filtering is carried out by forming a quasilinear left clone and a predetermined shape of the amplitude-frequency characteristic of the modulation device and demodulation necessary due to the implementation of the frequency dependency quadrupole parameters using the following mathematical expression:

;

;

where

;

;

;

;

;
A ₀ = r _a r _2н∂ + x _a x _2н∂ ; B ₀ = x _a r _2н∂ -r _a x _2н∂ ; R ₀ = r _∂ r _2n∂ + x _∂ x _2n∂ ;

;

;

; A = D _m -D _∂ ; B = E _m -E _∂ ; D = F _m -F _∂ ;
r _∂ = r ₁₁ r ₂₂ -x _11T x _22T -r ₁₂ r ₂₁ + x _12T x _21T -r _11T r _n + x _11T x _n ; r _2n∂ = -r ₂₂ + r _n ; r _a = r ₂₁ r _n -x _21T x _n ;

;

;

;
x _∂ = r ₁₁ x _22T + x _11T r ₂₂ -x _12T r ₂₁ -r _12T x _21T -r ₁₁ x _n -x _11T r _n ; x _2n∂ = -x _22T + x _n ; x _a = r ₂₁ x _n + x _21T r _n

;

;

;

;

;

;

;

α, β, γ are the optimal frequency dependences of the relations of the corresponding elements of the classical transmission matrix of the quadrupole a, b, c, d; d is the optimal frequency dependence of one of the elements of the classical transmission matrix; m _d is the optimal dependence of the transfer function module of the high-frequency part of the frequency modulation and demodulation device on frequency in the demodulation mode, satisfying the condition of physical feasibility; φ _d is a predetermined linearly decreasing phase dependence of the transfer function of the high-frequency part of the frequency modulation and demodulation device in frequency in the demodulation mode, satisfying the condition of ensuring the linearity of the left slope of the frequency response; x ₀ , x ₀ - given frequency dependences of the real and imaginary components of the resistance of the source of the frequency-modulated signal in the demodulation mode, equal to the frequency dependences of the real and imaginary components of the resistance of the imaginary source of high-frequency signals that occur when the DC source is turned on, in the modulation mode; r _n , x _n - given frequency dependences of the real and imaginary components of the resistance of the high-frequency load in both modes; r ₁₁ , r ₁₂ , r ₂₁ , r ₂₂ , x _11T , x _12T , x _21T , x _22T , are the given dependences of the real and imaginary components of the resistance matrix of a three-pole nonlinear element on the frequency and amplitude of the amplitude-frequency-modulated signal in demodulation mode

,

,

,

,

,

,

,

- the given dependences of the real and imaginary component elements of the resistance matrix of a three-pole nonlinear element on the frequency and amplitude of the low-frequency control signal in modulation mode; the remaining quantities have the meaning of intermediate notation in the interests of simplifying mathematical expressions. 2. A device for frequency modulation and demodulation of high-frequency signals connected between a source of high-frequency signals and a low-frequency load and consisting of a linear reactive four-terminal device, a nonlinear element connected in modulation mode to a source of a low-frequency control signal, a low-pass filter and a separation capacitance, characterized in that before a low-pass filter introduced a high-frequency load into the transverse circuit; a three-pole nonlinear e an element that is connected between a four-terminal and a high-frequency load according to a circuit with a common one of three electrodes, the four-terminal is made in the form of an overlapped T-shaped connection of four reactive two-terminal with resistances x _1n , x _2n , x _3n , x _4n, respectively, the second, third and the fourth two-terminal network is formed of two parallel connected serial circuits with parameters L _1k , C _1k , L _2k , C _2k , the parameters of these two-terminal networks are selected from the conditions for the formation of a quasilinear slope and a given shape of the amplitude-frequency characteristics in the frequency demodulation mode and conditions for ensuring the balance of amplitudes and phase balance in a given range of frequency changes and a given range of changes in the amplitude of the low-frequency control signal in the frequency modulation mode using certain mathematical expressions:

;

;

;

,
Where

;

;
x = a ₂ s _{1-a 1} s ₂ , y = a ₂ d ₁ + b ₂ c ₁ -a ₁ d ₂ -b ₁ c ₂ ; z = b ₂ d ₁ -b ₁ d ₂ ;

;

;

;

;

;

;

;

;

;

;

;

;

where

;

;

;

;

;

;
A ₀ = r _a r _2н∂ + x _a x _2н∂ ; B ₀ = x _a r _2н∂ -r _a x _2н∂ ; R ₀ = r _∂ r _2n∂ + x _∂ x _2n∂ ;

;

;

; A = D _m -D _∂ ; B = E _m -E _∂ ; D = F _m -F _∂ ;
r _∂ = r _11n r _22n -x _11Tn x _22Tn -r _12n r _21n + x _12Tn x _21Tn -r _11Tn r _нn + x _11Tn x _нn ; r _2n∂ = -r _22n + r _нn ; r _a = r _21n r _nn -x _21Tn x _nn ;
x _∂ = r _11n x _22Tn + x _11Tn r _22n -x _12Tn r _21n -r _12Tn x _21Tn -r _11n x _нn -x _11Tn r _нn ; x _2n∂ = -x _22Tn + x _нn ; x _a = r _21n x _нn + x _21Tn r _нn .

;

;

;

;

;

;

;

α, β, γ are the optimal ratios of the corresponding elements of the classical transfer matrix of the quadrupole a, b, c, d at given four frequencies ω _n = 2πf _n ; n = 1, 2, 3, 4 - numbers of the given frequencies; d is the optimal value of one of the elements of the classical transmission matrix at given four frequencies; m _∂n are the optimal values of the transfer function modulus of the high-frequency part of the frequency modulation and demodulation device at four predetermined frequencies in the demodulation mode, satisfying the condition of physical realizability; φ _∂n are the specified linearly decreasing phase values of the transfer function of the high-frequency part of the frequency modulation and demodulation device at the given four frequencies in the demodulation mode, satisfying the condition of ensuring the linearity of the left slope of the frequency response; r _0n , x _0n - set values of the real and imaginary components of the resistance of the source of the frequency-modulated signal in the demodulation mode, equal to the values of the real and imaginary components of the resistance of the imaginary source of high-frequency signals that occur when the DC source is turned on, in the modulation mode at the specified four frequencies; r _nn , x _nn - set values of the real and imaginary components of the resistance of the high-frequency load in both modes at the specified four frequencies; r _11n , r _12n , r _21n , r _22n , x _11Tn , x _12Tn , x _21Tn , x _22Tn , are the values of the real and imaginary components of the resistance matrix of the three-pole nonlinear element at the given four frequencies and four values of the amplitude-frequency-modulated signal amplitude in demodulation mode;

,

,

,

,

,

,

,

- the set values of the real and imaginary component elements of the resistance matrix of a three-pole nonlinear element at specified four frequencies and four values of the amplitude of the low-frequency control signal in modulation mode; k = 2, 3, 4 — numbers of the second, third, and fourth two-terminal devices of the overlapped T-shaped connection of four reactive two-terminal devices; x _1n - set resistance values of the first two-terminal at given four frequencies; the remaining quantities have the meaning of intermediate notation in the interests of simplifying mathematical expressions.

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