RU2060507C1 - Frequency-modulated radiospectrometer - Google Patents

Abstract

FIELD: radio measurement technology. SUBSTANCE: frequency-modulated radiospectrometer has antenna 1, high-frequency amplifier 2, mixer 3, intermediate-frequency amplifier 4, first, second, third local oscillators 5, 20, 21, first, second single-band mixers 6, 7, first, second band filters 8, 9, first second quadrature detectors 10, 11 subtraction unit 12, adding unit 13, first, second synchronous detectors 14, 15, modulating-frequency oscillator 16, recorder 17, DC amplifier 18, local oscillators control unit 19. Modulating-frequency oscillator 16 has sawtooth-voltage master oscillator whose reference output functions as second output of modulated- frequency oscillator 16 and is connected to second inputs of synchronous detectors 14, 15, master oscillator voltage amplifier, base-voltage clipper, peak-voltage clipper, voltage amplifier whose output functions as first output of modulating-frequency oscillator 16. Local oscillators control unit 19 has three adders, and subtracter whose combined first inputs function as input of local oscillators control unit 19, reference-voltage source, peak and base frequency deviation voltage amplifiers whose outputs function, respectively, as first and second outputs of local oscillators control unit 19 and are connected to reference outputs of clippers, first, second control units whose outputs function, respectively, as third and fourth outputs of local oscillators control unit 19. EFFECT: improved design. 3 dwg

Description

 The invention relates to a radio metering technique and can be used for precision radiometric measurements in the millimeter wavelength range.

 A known frequency-modulated radio spectrometer comprising an antenna, high-frequency amplifier, mixer, intermediate-frequency amplifier, first and second bandpass filters, first and second quadratic detectors, balance device, low-frequency amplifier, synchronous detector, low-pass filter, and also the first and second local oscillators, a local oscillator switch and a modulating frequency generator. In the indicated spectrometer, frequency modulation is carried out by alternately connecting the mixer heterodyne input to the first and second local oscillators through a local oscillator switch to the first and second local oscillators through a local oscillator switch with a frequency determined by the modulating frequency generator.

раза с вравнении со случаем амплитудной модуляции сигнала на входе редиометра.The spectrum at the receiver output using two bandpass filters having the same bandwidth is divided into two channels spaced apart in frequency. The center frequencies of these channels are selected so that, in the switching mode of the first and second local oscillators, the signal under investigation arrives in the first or second channel. The periodic components of the signals from the outputs of the channels are fed to a balanced device, where they are subtracted. As a result, the radiospectrometer measures the radiation of the observed line throughout the entire observation time, which makes it possible to increase its sensitivity in

times compared with the case of amplitude modulation of the signal at the input of the rediometer.

 The use of frequency modulation in the specified device when operating in the microwave and especially in the millimeter ranges entails the appearance of so-called “false” signals. In the antenna, antenna feeder, and input path of the radiometer, wave reflections at joints, path elements, etc. are inevitable. As a result, partially coherent waves with different delays arrive at the receiver input, and a change in the local oscillator frequency leads to a change in the interference conditions and, therefore, to changing the output voltage and reducing the measurement accuracy of a frequency-modulated radio spectrometer. The latter is its significant drawback.

 In FIG. 1 shows a structural diagram of a frequency-modulated radio spectrometer; in FIG. 2 block diagram of the control unit local oscillators (BUG); in FIG. 3 is a structural diagram of a modulating frequency generator (GMC); in FIG. 4 frequency response of an intermediate-frequency amplifier with indication of the analysis areas through two channels containing single-band mixers with bandpass filters at the outputs.

 A frequency-modulated radio spectrometer contains (see FIG. 1) an antenna 1, a high-frequency amplifier 2, a mixer 3, an intermediate-frequency amplifier (4), the first local oscillator 5, the first, second single-band mixers 6, 7, the first, second bandpass filters 8, 9, first, second quadratic detectors 10, 11, subtraction unit 12, summing unit 13, first, second synchronous detectors (SD) 14, 15, modulating frequency generator (GMP) 16, recorder 17, direct current amplifier (DC) 18, the control unit local oscillators (BUG) 19, the second local oscillator 20, the third local oscillator 21.

 The first, second single-band mixers 6 and 7 are made according to the scheme containing two balanced mixers, and a device that provides suppression of the mirror channel. The subtraction unit 12 is made with appropriately selected weighting coefficients for its two inputs. These weighting factors are equal to the weighting factors connected to the inputs of the subtraction unit 12 to the two inputs of the summing unit 13.

 The local oscillator control unit BUG 19 (see Fig. 2) contains the first, second, third adders 22-24, a subtractor 25, a constant voltage source 26, an amplifier 27 for the voltage of the upper boundary of the frequency deviation, an amplifier 28 for the voltage of the lower boundary of the frequency deviation, first, second control units 29, 30.

 The generator of the modulating frequency of the GMP 16 (see Fig. 3) comprises a rectangular voltage driver 31, a voltage amplifier 32 of the driver 32, a voltage limiter 33 from below, a voltage limiter 34 from above, and a voltage amplifier 35.

 The output of the voltage amplifier 35 is the first output of the GMP 16. The reference output of the rectangular voltage driver 31 is the second output of the GMP 16. The first output of the GMP 16 is connected to the input of the first local oscillator 5, and the second output is connected to the input of synchronous detectors 14, 15.

 The outputs of the amplifiers 27, 28 are the first and second outputs of the BUG 19 and are connected respectively to the reference inputs of the limiters 33, 34, which are the first and second inputs of the GMP 16.

 The first inputs of the first, second, third adder 22, 23, 24 and subtractor 25 are the input BUG 19, which is connected to the output of the UPT 18.

 The outputs of the first, second control units 29, 30 are the third and fourth outputs of BUG 19 and are connected respectively to the second and third local oscillators 20, 21.

 A frequency-modulated radio spectrometer operates as follows.

= f₀±

(1) где f_о несущая частота;
ΔF девиация частоты.Frequency modulation of the signal at the input of the intermediate frequency amplifier 4 is carried out by modulating the frequency f _{g1 of the} first local oscillator 15 according to the law of the "meander". Wherein
f

= f ₀ ±

(1) where f is _the carrier frequency;
ΔF frequency deviation.

Since the radiometer setting should not change with a change in f _о , there is a need for a corresponding change in the frequencies f _g2 and f _{g3 of the} second 20 and third 21 local oscillators while maintaining the equalities
lf _g2 -f _g3 l ΔF
(f _g2 + f _g3 ) / 2 f $\genfrac{}{}{0ex}{}{\text{about}}{\text{etc}}$ + Δf _about f _CR1 (2) where Δf is _the frequency offset of the first local oscillator 5;
f $\genfrac{}{}{0ex}{}{\text{about}}{\text{pr1}}$ the first intermediate frequency equal to the center frequency of the amplifier.

The carrier frequency f _about in the formula (1) is set by the level of the average value U _about from the control voltages U ₁ (t) and U ₂ (t) at the first and second inputs of the modulating frequency generator (GMP) 16.

(3)
Девиация частоты ΔF зависит от разности управляющих напряжений U₁(t) и U₂(t).f ₀ = f ₀ (U ₀ ) f

(3)
The frequency deviation ΔF depends on the difference between the control voltages U ₁ (t) and U ₂ (t).

ΔF Δ F (U ₁ -U ₂ ) (4)
The selectivity of the spectroradiometer is determined by the first 8 and second 9 tuned to the intermediate frequency f _CR2 (see Fig. 4) bandpass filters 8 and 9 with a passband P _a . The frequency range in which the possible rearrangement selective band (band analysis) P _a, P depends on bandwidth IF amplifier 4. By controlling the value of ΔF and the related frequencies f and f _{r2 r3} oscillators 20 and 21 can be moved _and P band analysis. Referring to FIG. 4, then such a movement P _a is a consequence of the approach or separation of regions 1 and 2, highlighted by the identical amplitude-frequency characteristics (AFC) of the bandpass filters 8 and 9 at the outputs of the first and second single-band mixers 6, 7. It is important that regions 1 and 2 are located symmetrically relative to the first intermediate frequency f _CR1 and their center frequencies f ₁ and f ₂ are separated from f _CR1 by an amount equal to ΔF / 2.

Changes in the frequency of the first local oscillator f _g1 lead to a change in the interference conditions of the waves reflected from the path inhomogeneities and, as a result, to unpredictable variations in the signal level at the output of the amplifier. This is especially noticeable in the millimeter wave range, where besides, external factors such as temperature, humidity, mechanical stresses that lead to changes in the electrical path length can be important. In addition, in the millimeter range, the reception band of P can be gigahertz, and for the implementation of a radiometer with frequency modulation, the frequency deviation ΔF ≥P is necessary.

 The influence of the path inconsistency is significant if the change in the frequency of the first local oscillator 5 is accompanied by an additional phase incursion ΔΦ of comparable or greater π / 2. With the electric path length l and frequency deviation ΔF.

f_o+

-2

f_o-

(с скорость света). Отсюда следует, что для характерного значения ΔF/f₀≃ 0,01(f₀~(50 100)ГГц)ΔΦ ≳ π/2 при геометрической длине волноводного тракта
L ≃ l ≳ 12,5f₀c 12,5λ где λ длина волны.ΔΦ 2

f _o +

-2

f _o -

(with the speed of light). It follows that for the characteristic value ΔF / f ₀ ≃ 0.01 (f ₀ ~ (50 100) GHz) ΔΦ ≳ π / 2 for the geometric length of the waveguide path
L ≃ l ≳ 12.5f ₀ c 12.5λ where λ is the wavelength.

Errors arising from frequency modulation can be eliminated if, without changing the settings of the radio spectrometer, the carrier frequency f _{о of the} first local oscillator 5 is shifted to the region where interference effects are least manifested or cause the same signal power increments ΔР _c1 and ΔР _c2 at the inputs of bandpass filters 8 and 9. In the latter case the output of the subtracting unit 12 increment? P? P _c1 and _c2 will be compensated and the output of the first synchronous detector 14 will be a voltage determined only by the difference in signal power output olosovyh filters 8, 9, equal to the difference of the measured signal power and the background radiation outside the band analysis _and n.

 The equalization of interference effects at the outputs of the bandpass filters 8 and 9 is facilitated by a servo system (SS) composed of a summing unit 13, a second synchronous detector 15, a direct current amplifier (DC amplifier) 18 with an object of regulation in the form of the first, second, and third local oscillators 5, 2, 21, controlled by a control unit of local oscillators (BUG) 19. The control system of the first local oscillator 5 also includes individual components of the modulating frequency generator 16.

и f_он= f_oo-

соответственно верхнее и нижнее значения частоты f_о.The tracking mode is always preceded by the frequency search mode f _о f _оо , at which the increments of the signal powers at the outputs of the bandpass filters 8 and 9, caused by frequency modulation, are the same, but become different in the case of detuning from it by δf _о :
ΔP _s1 (f _s ) ΔP _s2 (f _he ) (5)
_C1? P (f _s + δf _n)? P _c1 (f _s) (? P _c2 (f _He + + δf _n)? P _c2 (f _He)) - (Δ P _c1 (f _{OB of} δf) -ΔR _c1 (f _s ) (6) or
ΔP _s1 (f _he) ΔP _s2 (f _s ) (7)
ΔP _s1 (f _he + δ f _о) Δ P _s1 (f _he ) (ΔP _s2 (f _s + δf _o ) P _s2 (f _s )) (ΔP _s1 (f _he
δf _n)? P _c1 (f _He)), (8) where f _s = f _oo +

and f _he = f _oo -

respectively, the upper and lower values of the frequency f _about .

 The fulfillment of one of the relations (6) or (8) allows the second synchronous detector 15 to play the role of a discriminator of the tracking system (CC). Since the second SD 15 includes a low-pass filter (integrator) with a sufficiently large time constant at which the control object can be considered as inertialess, the SS is a tracking system with first-order astatism. Equality (5) or (7) (depending on the selected capture band) is fixed by changing the sign of the readings on the recorder 17 in the absence of a signal at the input of the high-frequency amplifier 2.

The search mode is carried out by shifting the output level of the CTF 18, which leads to a smooth change in frequency f _о and associated frequencies f _g2 and f _{g3 of the} second and third local oscillators 20 and 21 in accordance with formula (3). The phase of the master oscillator 31 in the GMP 16 ( 0 or π) depends on which of the two relations (5) and (6) or (7) and (8) are satisfied, and is selected so that when entering the tracking mode, tracking of changes in the selected frequency f _{оо is} provided, i.e. so that the second SD 15 plays the role of a discriminating tracking error f _o f _oo. In the measurement process, when a signal from antenna 1 is supplied to the high-frequency amplifier 2, the CC is in tracking mode.

Selectivity rf determined by the fundamental channel _{and the} bandwidth P (see. FIG. 4) identical band pass filters 8 and 9 included after the respective single-sideband mixers 6 and 7. The reception in the band n _and the signal analysis, depending on the values of the instantaneous frequency f _r1 of the first local oscillator 5 alternately pass through the first, then through the second bandpass filter 8. 9. Thus passband IF amplifier 4 is several times the strip analysis _and n (n> P _a) that is made in order to increase the accuracy of the analysis of the spectral composition and Followed by introducing radiation into radio spectrometer elements sequential spectral analysis, implemented by changing the frequency deviation ΔF and simultaneously with it changes the frequency of the second and third local oscillators 20, 21 while maintaining the relations (1). The ratio P / P _a depends on the required accuracy of the analysis. The change in the frequency deviation ΔF in accordance with expressions (3) and (4) occurs under the action of voltage U ₁ U _o + U _Δ at the output of the first adder 22 of the control unit of the local oscillators 19 (see Fig. 2) and voltage U ₂ U _o U _Δ at the output of the subtractor 25 (U _{Δ is the} voltage of the reference voltage source 26 supplied to the second of the first adder 22 and the subtractor 25).

The voltages U ₁ and U ₂ from the outputs of the first adder 22 and subtractor 25 are respectively supplied to the inputs of the voltage amplifiers 27, 28 ΔF of the first local oscillator 5 and then, after the necessary level conversion, to the reference inputs of the voltage limiter 33 from below and the voltage limiter 34 from above to the high-frequency generator 16 ( see Fig. 3). At the (signal) first inputs of the limiters 33 and 34 is supplied from the voltage amplifier of the master voltage generator 32 of the type "meander" of the master voltage generator 31 of a rectangular shape.

Thus, at the output of the voltage limiter 34, there will be a voltage from above, the upper level of which determines the upper value of the instantaneous frequency f _g1 , and its lower lower value. This correspondence is established by selecting the voltage U _{Δ of the} voltage of the reference voltage source 26, the transmission coefficients 27 and 28, as well as the gain and amplitude characteristics of the voltage amplifier 35 in the BUG 19. The specific form of the amplitude characteristics of the voltage amplifier 35 depends on the type of generator used as the first local oscillator 5 and how to rebuild it.

= f_c+

до
f

= f_c+

f

где f_с f_о + f_пр или f_с f_о f_пр1 (f_пр1

f_o-f

) в зависимости от вида преобразования с f_пр1 f_с f_о или f_пр1 f_о f_с;
Δf_о смещение несущей частоты перевого гетеродина 5, отработанное системой слежения за равенством выходных напряжений на выходах синхронных детекторов 14, 15. Поэтому полоса пропускания УПЧ 4 должна выбираться с учетом не только спектральной ширины исследуемой области принимаемого излучения, но и возможных значений l Δf_о l что приводит в результате к увеличению П. Изменение частоты настройки радиоспектрометра происходит под управлением источника опорного напряжения 26, имеющего для этого необходимые установочные элементы.The voltage from the outputs of the first adder 22 and subtractor 25 in the BUG 19 is also supplied to the second inputs of the second and third adders 23, 24, respectively, to the first inputs of which are connected together the control voltage from the output of the CTF 18. Further, the voltage U ₃ U _o + + U _Δ + αU _о from the output of the second adder 23 and voltage U ₄ U _o U _Δ + βUо from the output of the third adder 24, converted in control units 29 and 30, are supplied respectively to the control inputs of the second and third local oscillators 20, 21. Weighting factors α and β on the first inputs of adders 23 and 24, and so the gain factors and the shape of the amplitude characteristics of the control units 29, 30 are selected so that relations (2) are satisfied. The movement of the analysis band Pa (frequency tuning) is possible in the range from
f

= f _c +

before
f

= f _c +

f

where f _a f _a + f f or _{a straight} f _about f _pr1 (f _pr1

f _o -f

) depending on the type of transformation with f _pr1 f _s f _o or f _pr1 f _o f _s ;
Δf _about the carrier frequency offset of the first local oscillator 5, worked out by the system for monitoring the equality of output voltages at the outputs of synchronous detectors 14, 15. Therefore, the passband of the IF 4 must be selected taking into account not only the spectral width of the studied region of the received radiation, but also the possible values of l Δf _о l which results in an increase in P. A change in the tuning frequency of the radio spectrometer is controlled by a reference voltage source 26, which has the necessary mounting elements for this.

The voltage from the outputs of the bandpass filters 8, 9 are detected by quadratic detectors 10, 11, the signals from the outputs of which are fed to the subtraction unit 12. The differential signal from the output of the subtraction unit 12 is synchronously detected in the first LED 14, the output voltage of which corresponds to the power measured in the band П _а input signal, which is recorded by the registrar 17.

 As the first local oscillator 5, you can use the backward wave lamp (BWT), with the possibility of tuning with an almost linear dependence of the generation frequency on the voltage on the slow-wave system. Since the control voltage in the BWT is several hundred volts, the corresponding requirements arise for the voltage amplifier 35, from the output of which a control voltage is supplied to the BWT. The voltage amplifier 35 is in the form of an amplifier stage with an amplitude characteristic that provides a given dependence (3).

 As the second and third local oscillators 20, 21, known transistor generators with frequency tuning using a nonlinear capacitance (varactor) or inductance are used. In the latter case, the dependence of the magnetic permeability of the ferromagnetic material used in the nonlinear inductance on the control current is used.

 The summing unit 13, the subtraction unit 12, as well as the adders 22, 23 and 24 and the subtractor 25 are performed on operational amplifiers. Amplifiers 27 and 28 of voltage, of the first local oscillator 5 and control units 29, 30 are also performed on operational amplifiers. The amplitude characteristic of control units 29, 30 is formed by using non-linear elements in the negative feedback circuit with the corresponding relation (3) of the current-voltage (or amperes) -volt) characteristic. To implement single-band mixers 6, 7, a circuit with phase suppression of the mirror channel is used.

до f_o+

вызывает изменение амплитуды напряжения на гетеродинном входе смесителя 3 от U_г1- до U_г1+ и соответствующее изменение выходного напряжения первого СД 14 от
U_вых-= χ K_p(-

)

до U_вых+= χ K_p(

-

)

где χ коэффициент пропорциональности;
U_о номинальное напряжение первого гетеродина 5, приложенное к смесителю 3;
Кр коэффициент усиления входной разности между средней мощностью сигнала

в полосе анализа П_а и фонового излучения

в той же полосе П_а, но в области, расположенной за пределами полосы анализа и отстоящей от нее на частотный интервал ΔF. Таким образом, на выходной сигнал U_вых(t) первого СД 14 накладывается мультипликативное мешающее воздействие и
U_вых(t)

(t)
При отсутствии рассогласованной в высокочастотном тракте U_вых(t) соответствует полезной составляющей:

K_p(

-

)

соnst, если входной сигнал стационарен. Рассогласование тракта ведет к наложению на полезную составляющую

мультипликативного воздействия в форме множителя μ_ош(t) 1+

U $\genfrac{}{}{0ex}{}{\text{2}}{\text{г1-}}$ (t)-U $\genfrac{}{}{0ex}{}{\text{2}}{\text{г1+}}$ (t)

(9) где U_г1-(t) и U_г1+(t) медленные функции времени с характерным временным масштабом, превышающим постоянную времени первого СД 14 и второго СД 15.The effectiveness of eliminating the influence of the inconsistency of the high-frequency path can be estimated by comparing the width of the noise track at the output of the first SD 14 with and without SS. In the absence of SS (blocks SD 15 and UPT 18) the change in the frequency of the first local oscillator 5 from f _o -

to f _o +

causes a change in the amplitude of the voltage at the heterodyne input of the mixer 3 from U _g1 - to U _{g1 +} and a corresponding change in the output voltage of the first LED 14 from
U _o - = χ K _p ( -

)

to U _{o +} = χ K _p (

-

)

where χ is the coefficient of proportionality;
U _{about the} rated voltage of the first local oscillator 5, applied to the mixer 3;
Cr gain of the input difference between the average signal power

n in the band analysis _and background radiation and

in the same band P _a , but in the region located outside the analysis band and separated from it by the frequency interval ΔF. Thus, a multiplicative interfering effect is superimposed on the output signal U _o (t) of the first LED 14 and
U _o (t)

(t)
In the absence of a mismatch in the high-frequency path, U _o (t) corresponds to the useful component:

K _p (

-

)

const if the input signal is stationary. Path mismatch leads to superposition on the useful component

multiplier effect in the form of a factor μ _osh (t) 1+

U $\genfrac{}{}{0ex}{}{\text{2}}{\text{g1-}}$ (t) -U $\genfrac{}{}{0ex}{}{\text{2}}{\text{g1 +}}$ (t)

(9) where U _g1- (t) and U _{g1 +} (t) are slow time functions with a characteristic time scale exceeding the time constant of the first LED 14 and the second LED 15.

(t)-1

≲ (KCB)²

КCВ Е_max/Е_min максимальный из коэффициентов стоячей волны на частотах f_г1f_о±ΔF/2, а Е_max и Е_min соответствующие этим значениям f_г1 максимальная и минимальная амплитуды электрического поля в тракте первого гетеродина 5, U_min минимально возможные (соответствующее Е_min) напряжение на гетеродинном входе смесителя 3.Notice, that:

(t) -1

≲ (KCB) ²

KSV E _max / E _{min the} maximum of the standing wave coefficients at frequencies f _g1 f _о ± ΔF / 2, and E _max and E _min corresponding to these values f _{g1 the} maximum and minimum amplitudes of the electric field in the path of the first local oscillator 5, U _{min the} minimum possible ( corresponding E _min ) voltage at the heterodyne input of the mixer 3.

. Выигрыш Q за счет подавления эффектов рассогласования тракта гетеродина с помощью СС определяется модулем разности μ_ош(t)-1:
Q

Поскольку СС является следящей системой с астатизмом первого порядка и постоянные времени первого СД 14 и второго СД 13 одинаковы, то динамическая ошибка слежения отсутствует, если отслеживаемая частота f_ооменяется по линейному закону и величина Q может быть достаточно большой, поскольку CC стремится выполнять значения U_{г1+ и} U_г1-. Максимальное значение Q ограничивается флуктуационной ошибкой в СС. Таким образом, радиоспектрометр позволяет существенно повысить точность радиометрических измерений за счет устранения интерференционных эффектов в тракте первого гетеродина 5. Внешне это проявляется в устранении медленных вариаций шумовой дорожки на регистраторе 17.Expression (9) gives a measure of the deviation of the measured value of the relative signal power from the true value

. The gain Q due to the suppression of the effects of the mismatch of the local oscillator path using SS is determined by the difference modulus _μsh (t) -1:
Q

Since the SS is a tracking system with first-order astatism and the time constants of the first LED 14 and the second LED 13 are the same, there is no dynamic tracking error if the monitored frequency f _оо varies linearly and Q can be quite large, since CC tends to fulfill the values U _{g1 + and} U _g1-. The maximum value of Q is limited by the fluctuation error in the SS. Thus, the radio spectrometer can significantly improve the accuracy of radiometric measurements by eliminating interference effects in the path of the first local oscillator 5. Externally, this is manifested in the elimination of slow variations of the noise track on the recorder 17.

Claims (1)

 A frequency-modulated radio spectrometer comprising a series-connected antenna, a high-frequency amplifier, a mixer with a first local oscillator connected to it, an intermediate-frequency amplifier, a first-pass filter, a first quadratic detector and a second band-pass filter, a second quadratic detector, a first synchronous detector connected in series, the recorder, the outputs of the first and second quadratic detectors are connected to the inputs of the subtraction unit, the output of which is connected to the first input the first synchronous detector, the input of the first local oscillator is connected to the first output of the modulating frequency generator, the second input of which is connected to the second input of the first synchronous detector, characterized in that the second local oscillator, the first single-band mixer and the third local oscillator, the second single-band mixer, are connected in series connected summing unit, the inputs of which are connected to the outputs of the first and second quadratic detectors, the second synchronous detector connected to the second a modulating frequency generator, a direct current amplifier, a local oscillator control unit, the first fourth outputs of which are connected respectively to the inputs of the first and second modulating frequency generator, second and third local oscillators, the local oscillator control unit contains first, second and third adders and a subtractor, the first inputs of which are the input of the local oscillator control unit, a constant voltage source, the output of which is connected to the second input of the first adder and the second input of the subtractor, an amplifier the upper limit of the frequency deviation of the first local oscillator and the voltage amplifier of the lower boundary of the frequency deviation of the first local oscillator, the outputs of which are the first and second outputs of the local oscillator control unit, and the inputs are connected respectively to the first outputs of the first adder and subtracter, the first and second control units whose inputs are connected respectively, to the outputs of the first and second adders, and the outputs are respectively the third and fourth outputs of the local oscillator control unit, the second inputs are second of the first and third adders are connected respectively to the first outputs of the first adder and subtracter, the modulating frequency generator contains a rectangular voltage master oscillator, the reference voltage output of which is the second output of the modulating frequency generator and connected to the second inputs of the first and second synchronous detectors, and the control output to a series-connected voltage amplifier of the master oscillator, a voltage limiter, the output of which is the first output of the modulating generator frequency, the reference inputs of the voltage limiter at the top and the voltage limiter at the bottom are respectively the first and second input of the modulating frequency generator.

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