RU2196345C2 - Way for radio acoustic atmosphere sounding - Google Patents

Abstract

FIELD: meteorology. SUBSTANCE: invention refers to methods establishing parameters of boundary layer of atmosphere, it can be used to determine refractive index of atmosphere on surface route of passage of electromagnetic waves. In correspondence with way acoustic packet containing pulses with duration τ_s0 and repetition frequency F_s0 are emitted with τ_s0<1MF_s0, packet is irradiated with electromagnetic pulses with duration τ_s0, in which spectrum there are frequencies mF_s0, where m= 1, 2,...M. Frequency F_e0 is tied up with frequency F_s0 by relations λ_s = λ_e/2; C_e/F_e0, where C_e is velocity of light, λ_s = C_s/F_s0;

is velocity of sound in air at temperature T lying in specified interval. Echo signals are received on frequencies close to mF_a0, values of frequencies of Doppler shifts F_D1, F_D2 ..., F_dm for various ranges and phase difference of signals on various Doppler frequencies are measured. Humidity profile is determined by phase difference for entire sounding range. Altitude profile of temperature is found by frequencies of Doppler shifts with due account of values of humidity. Surface value of pressure is measured and altitude profile of air refractive index is computed. EFFECT: raised measurement accuracy. 2 dwg

Description

 The invention relates to meteorology, and in particular to methods for determining the parameters of the boundary layer of the atmosphere, and can be used to determine the index of refraction of the atmosphere on the surface path of passage of electromagnetic waves.

The refractive index n of radio waves in the Earth’s atmosphere is recorded through the refractive index N in the form [1. Reference for radar. T.1. Basics of radar. Per. with English, ed. Ya.S. Yitzhoki. - M .: Owls. radio. 1976. 456 p. Radar Handbook. Editor-ln-Chief Merrill I. Skolnik. McGraw-Hill Book Company 1970.]
n = 1 + N • 10 ⁶ ,
where N = K ₁ p / T + K ₂ e / T ² (1)
where T is the temperature in Kelvin, p is the total atmospheric pressure in mbar, e is the partial pressure of water vapor, K ₁ = 77.6 K / mbar, K ₂ = 3.73 • 10 ⁵ K ² / mbar. The error in the determination of N by the formula (3) is not more than 0.5% for frequencies f≤30 GHz at commonly encountered intervals of changes in pressure, temperature, and humidity.

где p_{1, 2} - давление, мбар; t_m - средняя температура слоя воздуха, ^oC.A known method for determining the values and gradients of N, which consists in the fact that at different heights of the weather tower installed instruments for measuring temperature and humidity; the pressure is measured with a barometer, for example a cup, at a low height (2 m). Repeated measurements are carried out using the indicated instruments and the average statistical value of the refraction index for a given area is calculated using the barometric formula and equation (1). [2. Rukina A. N. Study of the refractive index of air in the lower 300-meter atmosphere layer in the Kaluga Region. Preprint 85. M .: IRE AN SSSR. - 1972. 18 p.]
In atmospheric layers up to 2000 m thick, use the Babinet barometric formula [3. Ioffe M.M., Prikhodko M.P. Handbook of an aeronautical meteorologist. - M .: Military Publishing House of the Ministry of Defense of the USSR, 1977.330 s. P. 15.]

where p _{1, 2} - pressure, mbar; t _m - average temperature of the air layer, ^o C.

A known method for determining the values of N, which consists in the fact that inside the container, instruments for measuring temperature, humidity and pressure are installed, the container is launched using a balloon and the instrument readings are transmitted to the Earth using a radio transmitter. Such measurements are called radiosondes. The total error of such a determination is largely due to errors of meteorological sensors, rather than the inaccuracy of the values of the coefficients K ₁ , K ₂ in formula (1). So, with measurement errors ΔР = ± 2 mbar, ΔТ = ± 1 K, Δе = ± 5% (the usual accuracy of radiosonde measurements), the mean square error in calculating N is ΔN = ± 4.1, and the uncertainty of the coefficients K ₁ , K ₂ in formula (3) gives an additional error δN = ± 1.6 [1].

[4. Казаков Л.Я.. Ломакин А.Н. Неоднородности коэффициента преломления воздуха в тропосфере. - М.: Наука.- 1976. - 164 с.], с. 55-61. Рефрактометр может быть установлен на радиозонде, на самолете, на метеобашне, на мачте корабля. Суммарная относительная ошибка рефрактометра для наиболее часто употребляемого предела измерений в 50 N-единиц составляет 2% [4, с.71].A known method of determining the values of N, which consists in measuring the dielectric constant of air (ε) using a refractometer and calculating the refractive index by the formula

[4. Kazakov L.Ya .. Lomakin A.N. Inhomogeneities of the refractive index of air in the troposphere. - M .: Nauka. - 1976. - 164 p.], P. 55-61. The refractometer can be installed on a radiosonde, on an airplane, on a weather tower, on a ship’s mast. The total relative error of the refractometer for the most commonly used measurement limit of 50 N-units is 2% [4, p. 71].

According to the metrological analysis of radio meteorological data [5. Bean B.R., Danton E.J. Radio meteorology. - Leningrad: Hydrometeoizdat. -1971. 362 p. Fig. 2.1. ] to obtain an error of not more than ± 1 N-units. The following acceptable values of measurement errors were obtained: ΔТ = 0.788 K, Δр = 3.7 mbar, Δе = 0.22 mbar (relative humidity should be determined with an error not worse than Δе = 0.33% at a temperature of 35 ^o С or Δе = 3, 0% at 0 ^o C).

 The listed methods are contact and have common disadvantages: 1) the methods do not provide spatial averaging of the refractive index; 2) it is impossible to obtain operational data on the value of the refractive index on an arbitrarily specified propagation path of the radio beam of a ground-based radio station; 3) the methods cannot be used for real-time monitoring; 4) devices implementing these methods are not suitable for use in the airport area due to interference with air traffic.

 To eliminate the above drawbacks, it is necessary to apply non-contact methods for all-weather sounding of the atmosphere from the Earth's surface.

There is a method of finding an evaporation waveguide above a sea surface using a radiometer (wavelength λ = 2.1 cm) with an antenna having a main beam with a width of about 1 ^o and a low level of side lobes (parabolic reflector with a diameter of 2.5 m, an irradiator in the form of a scalar horn ) The antenna is suspended on board the vessel. Antenna scanning was carried out near the zenith angles θ = 85 ^o . . . 95 ^o . With the vertical polarization of the antenna, a burst of radio brightness temperature was detected at an angle θ≈90 ^o . [6. Koshel K.V., Slavutsky L.A., Shevtsov B.M. Propagation of UK and microwave radio waves over the sea. Vladivostok: Dalnauka. 1993. -160 p.], P.136-141.

 The disadvantage of the radiometric method of sensing the atmosphere is its low accuracy. Radiometric measurements were not confirmed by simultaneous independent meteorological measurements.

A known method of assessing the attenuation and refraction of radio waves above the sea surface using two-frequency radar sensing (λ = 3; 10 cm) at low elevation angles. Transceiving antenna Omnidirection had beamwidth θ _r = 0.75 and 2,5 ^{o °} in a horizontal plane, θ = 20 ^° _in a vertical plane and located at a height of 25-26 m. Parcel 0,4-0 pulse duration, 8 μs. The method is based on the reception of backscattering of radio waves by an excited sea surface (as a result of resonant Bragg scattering) [6, p. 126-135].

 The disadvantage of the radar method of sensing the atmosphere is its limited use: the method cannot be used when propagating radio waves over land and at high elevation angles.

 A known method for determining the refractive index of radio waves in the boundary layer of the atmosphere, based on a theoretical model [7. Andrianov V.A., Rakitin B.V. // Radio engineering and electronics, 1978. T. 23. 10. S. 2031-2038]. To apply the model, it is necessary to measure the altitude profiles of temperature and wind speed with an acoustic locator, as well as clarify the nature of atmospheric inhomogeneities. The disadvantage of this method is the restriction of its use only by certain weather conditions, since the presence of layers in the surface layer limits the applicability of the model [7].

 A common drawback of methods for acoustic and radar sounding of the atmosphere is the use of natural reflectors of acoustic or electromagnetic waves, the occurrence of such reflectors is due to local turbulence of the atmosphere, which may be absent at different heights in some weather conditions.

Closest to the claimed combination of features is a method of radio-acoustic sounding of the atmosphere [8. Orlov M. Yu., Yurchak B.S. On the possibility of determining humidity in the surface layer of the atmosphere by radio-acoustic method. // Proceedings of the Institute of Experimental Meteorology, 1985, 38/121, p. 14-20], which consists in sending an acoustic package to the atmosphere in the form of a package of sinusoidal oscillations with a carrier frequency F _s from the Earth’s surface, accompanying it with radio pulses with a carrier frequency F _e from the Doppler radar, receiving electromagnetic signals reflected from the disturbed air volume (echo signals), when the Bragg condition λ _s = λ _e / 2 is fulfilled, where λ _s , λ _e are the lengths of acoustic and electromagnetic waves in the reflection region, the altitude temperature and temperature profiles are determined by the Doppler shift of the received echo signals According to the attenuation of the echo signals, they find the altitude profile of humidity, measure the surface pressure value and calculate the altitude profile of the refractive index of air.

 The determination of altitude profiles of temperature and wind speed using radio-acoustic sounding of the atmosphere and the possibility of improvement are described in detail in the literature, see, for example, [9. Kallistratova M.A., Kon A.I. Radio sounding of the atmosphere. M .: Science. 1985. 197 p.], P. 162-165. The possibility of radio-acoustic measurement of the moisture profile is based on the dependence of the amplitude of the reflected signal on the sound absorption coefficient, which in turn is determined by the temperature and relative humidity of the air. However, since the amplitude of the received signal depends on many factors, in particular, on wind drift and turbulence intensity, the accuracy of this method cannot be high [9, p. 165].

 The main disadvantage of the prototype is the low accuracy of measuring the altitude course of humidity, due to the following sources of error.

External sources:
1. Additional sound absorption caused by atmospheric turbulence.

 2. The Bragg condition can be fulfilled only in some parts of the sensing distance; in a stratified atmosphere, this leads to a different degree of tuning of the frequency of the Doppler radar to the acoustic wavelength, and hence to an additional decrease in the amplitude of the reflected signal.

 3. The effect of the speed and direction of the wind and its pulsations on the magnitude of the echo signal.

Internal source:
4. Insufficient accuracy of measuring the microwave power of the received echo signal: with the usual error in measuring the microwave power ratio δ _q = ± 0.5 dB, the sound attenuation coefficient at F _s = 4 kHz is determined with an error of up to δ = 100%, with increasing accuracy to δ _q = ± 0.1 dB, it is possible to achieve δ = 10% [8, p. 17].

 Experimentally obtained [10. Ulyanov Yu.N. Accuracy of determination of air humidity by two-frequency radio-acoustic sounding. // Tr. 10 All-Union Sympos. on laser and acoustic sounding of the atmosphere. Part 2.-Tomsk. 1989. S. 107-111] that the prototype method allows you to measure the moisture profile only in calm conditions.

Improving the accuracy of measuring the microwave power of the received echo in the prototype method to δ _q = ± 0.1 dB (2.3%) leads to the following consequences. With the output power of an acoustic transmitter, for example, 10 W, the order of the received echo signals will be 10 ^-9 ± 2.3 • 10 ^-11 W, i.e. the error in measuring the amplitude of the echo signals is of the same order as the level of its pulsations. The sensitivity of the receiver should be at least 10 ^-11 watts.

 Thus, taking into account the known improving technical solutions, the prototype method cannot be applied in wind, and a simple increase in the accuracy of measuring the microwave power ratio cannot give the desired increase in the accuracy of measuring the moisture profile in this way.

 The basis of the invention is the task of improving the accuracy of determining the altitude profile of the refractive index of air in the boundary layer of the atmosphere by increasing the accuracy of finding altitude profiles of temperature and humidity, with an expanded range of permissible winds, with an increase in the dynamic range of the receiver up to the threshold sensitivity level (if only the echo signal fixed).

- скорость звука в воздухе при температуре Т, лежащей в заданном интервале от T_min до Т_mах, принимают эхо-сигналы на частотах, близких к mFeo, измеряют значения частот доплеровских смещений F_д1, F_д2,..., F_дM для различных дальностей и разность фаз сигналов на разных доплеровских частотах, по разности фаз определяют профиль влажности для всего расстояния зондирования, по частотам доплеровских смещений с учетом значений влажности находят высотный профиль температуры.This technical result is achieved by the fact that in the method of radio-acoustic sounding of the atmosphere, which consists in sending a packet of acoustic vibrations to the atmosphere from the Earth’s surface, accompanying the packet with radio pulses from the Doppler radar, receiving electromagnetic signals reflected from the disturbed air volume (echo signals), when the Bragg condition is fulfilled, λ _s = λ _e / 2, where λ _s , λ _e are the lengths of the acoustic and electromagnetic waves in the reflection region, the altitude profiles of the temperature are determined from the characteristics of the echo signals tours and humidity, measure the surface pressure value and calculate the altitude profile of the refractive index of air, according to the invention emit an acoustic packet of duration τ _s , consisting of pulses of duration τ _s0 , with a repetition rate of F _s0 , τ _s0 <1 / MF _s0 , irradiate the packet with electromagnetic transmissions duration τ _e , in the spectrum of which there are frequencies mF _e0 , where m = 1, 2, ... M, and the frequency F _e0 is related to the frequency F _{s0 by the} relations λ _s = λ _e / 2, where λ _e = c _e / F _e0 , c _e is the speed of light, λ _s = c _s / F _s0 ,

- the speed of sound in air at a temperature T lying in a predetermined range from T _min to T _max, receiving echo signals at frequencies close to mFeo, measured values of Doppler frequency shifts F _d1, F _d2, ..., F _Dm for any the distance and phase difference of the signals at different Doppler frequencies, the moisture profile is determined from the phase difference for the entire sensing distance, the altitude temperature profile is found from the frequencies of Doppler shifts taking into account the humidity values.

 The basis of the proposed method of radio-acoustic sounding is a previously unused physical effect of backscattering of an electromagnetic wave by an acoustic packet, forming thin layers of air seal (with increased dielectric constant), normal to the direction of propagation and spaced a distance multiple of half the length of the electromagnetic wave. When such a packet is irradiated with an electromagnetic package of M multiple radio frequencies (for which one or more half-waves fit between the layers of air compression), echo signals appear at these radio frequencies, which corresponds to their interaction with M sound harmonics.

 Determination of the altitude profile of the temperature in the proposed method.

According to the Laplace formula for a dry atmosphere
T = c _sd / q ² , (2)
where c _{sd is the} speed of sound in dry air, q = (kR / m _in ) ^1/2 = 20.053 is a constant, slightly dependent on air humidity, k is the ratio of specific heat capacities of air at constant pressure (C _p ) and constant volume (C _v ), R is the gas constant, m _in is the molecular mass of air.

The Doppler shift F _{d of the} frequency of the echo signal during radio sounding depends on the speed of sound c _s in a real atmosphere as
c _s = F _d λ _e / 2. (3)
The speed of sound c _s in a real atmosphere is related to humidity by the ratio [9, p. 32]
c _sd = c _s (1 + 0.28h) ^-1/2 , h = e / p, (4)
where h = e / p is the molar concentration of water vapor, in percent.

 According to [11. Fukushlma M., Tanaka H. and Furuhama Y. Radio, acoustic and radio-acoustic sounder. // J. Meteorol. Soc Japan. V. 22, 121. 1976. P. 427-442] when measuring temperature by radio-acoustic method without taking into account humidity, ie according to formulas (2), (3), the maximum error reaches ΔТ = ± 2.2 K. However, this is a rather large error, and it should be reduced.

 If we measure humidity over the entire sensing distance and take into account the humidity values in formula (4), we can reduce the error in determining the temperature profile due to the error in finding humidity at a specific distance to ΔТ≤ ± 0.5 K.

 Determination of humidity by measuring the phase shift of the echo signals at two different frequencies (dispersion algorithm) in the proposed method. The phase shift is due to the interaction of sound with air molecules, and therefore depends only on atmospheric humidity and does not depend on dynamic and temperature turbulence.

Below are the ratios obtained by us for determining air humidity by measuring the phase shift of the echo signals during two-frequency radio-acoustic sounding. According to [12. Ultrasound. Little Encyclopedia. - M.: Soviet Encyclopedia. 1979. 400 pp.] The dispersion of the speed of sound in air is characterized by δc _s / c _s = (c _so0 -c _s0 ) / c _s0 , where c _s0 and c _so0 are the speed of sound for very small and very large frequencies; the value of δc _s / c _s does not exceed 0.032%.

где f_p, Гц - частота релаксации, величина которой определяется выражением [9, с.39]

Из формул (5), (6) получим зависимость фазового сдвига Δφ от дальности зондирования R для эхо-сигналов, полученных зондированием на звуковой частоте f, относительно опорной частоты f₀, на которой дисперсионный эффект пренебрежимо мал. Обозначим

вследствие малости величины х можем записать

откуда

По определению частоты 2πf = -Δφ/Δt; -
t=R/c_s; Δt/Δc_s = -R/c $\genfrac{}{}{0ex}{}{\text{2}}{\text{s}}$ , отсюда 2πf = Δφc $\genfrac{}{}{0ex}{}{\text{2}}{\text{s}}$ /(RΔc_s), R = Δφc_s/(πfx).
Подставим в последнее выражение Δφ = Δφ^°π/180^°, получаем

Упростим последнюю формулу, учтя в ней неравенство 1>>(f/f_p)², отражающее реально существующие в атмосфере величины влажностей, окончательно имеем

Здесь c_s - скорость звука, средняя на дистанции зондирования R.Now the dependence of the speed of sound on frequency [13. Bergman L. Ultrasound and its use in technology. Per. with him. 2nd ed. - M., 1957] can be written as

where f _p , Hz is the relaxation frequency, the value of which is determined by the expression [9, _p . 39]

From formulas (5), (6) we obtain the dependence of the phase shift Δφ on the sounding range R for echo signals obtained by sounding at sound frequency f, relative to the reference frequency f ₀ , at which the dispersion effect is negligible. We denote

due to the smallness of x, we can write

where from

By frequency definition, 2πf = -Δφ / Δt; -
t = R / c _s ; Δt / Δc _s = -R / c $\genfrac{}{}{0ex}{}{\text{2}}{\text{s}}$ , hence 2πf = Δφc $\genfrac{}{}{0ex}{}{\text{2}}{\text{s}}$ / (RΔc _s ), R = Δφc _s / (πfx).
We substitute in the last expression Δφ = Δφ ^° π / 180 ^° , we obtain

We simplify the last formula, taking into account the inequality 1 >> (f / f _p ) ² , which reflects the actual humidity values in the atmosphere, we finally have

Here c _s is the speed of sound, the average at the sensing distance R.

откуда

Пусть для расстояния зондирования R-ΔR получены эхо-сигналы с двумя кратными частотами f=F_s2, nF_s2. Разность фаз эхо-сигналов равна

откуда

Подставим в квадратное уравнение (6) значения f_p=f_p1 и получим решение для величин влажности h₁ (усредненной на расстоянии зондирования R) и h₂ (усредненной на расстоянии зондирования R-ΔR).When an acoustic packet is emitted with two multiple frequencies f = F _s1 , mF _s1, the phase difference of the echo signals for the sounding distance R is

where from

Let echo signals with two multiple frequencies f = F _s2 , nF _s2 be obtained for the sensing distance R-ΔR. The phase difference of the echo is

where from

We substitute the values f _p = f _p1 into quadratic equation (6) and obtain a solution for the values of humidity h ₁ (averaged over the sounding distance R) and h ₂ (averaged over the sounding distance R-ΔR).

Двузначность решения квадратного уравнения (6) устраняем с помощью измерений приземного значения влажности h₀ и последующего итеративного перехода к остальным высотам зондирования с учетом высотного профиля температуры. Это оказывается возможным благодаря небольшому изменению влажности с высотой. Согласно [9, с. 35] в нижнем слое до 1 км относительная влажность изменяется до 10%.

The ambiguity of the solution of the quadratic equation (6) is eliminated by measuring the surface value of humidity h ₀ and the subsequent iterative transition to the remaining sensing heights, taking into account the altitude temperature profile. This is possible due to a slight change in humidity with height. According to [9, p. 35] in the lower layer up to 1 km, relative humidity varies up to 10%.

Значение h вместе с величиной температуры Т для той же высоты подставляем в формулу (1) для индекса преломления, находим
N=(p/T)(K₁+K₂h/T). (10)
Возможность определения влажности h по предложенному в данной заявке дисперсионному алгоритму связана с величиной турбулентности атмосферы: при наличии турбулентности возникают вариации фазы отраженного сигнала, которые должны быть меньше набега фазы, вызываемого дисперсией звука во влажной атмосфере.From the last two relations we obtain the average humidity in the layer with a thickness ΔR from R-ΔR to R, which we assign to the sensing distance R-ΔR / 2,

The value of h together with the temperature T for the same height is substituted into formula (1) for the refractive index, we find
N = (p / T) (K ₁ + K ₂ h / T). (10)
The possibility of determining humidity h using the dispersion algorithm proposed in this application is related to the amount of atmospheric turbulence: in the presence of turbulence, variations in the phase of the reflected signal arise, which should be less than the phase incursion caused by sound dispersion in a humid atmosphere.

 In FIG. 1 is a structural diagram of a radio-acoustic device (radar) for implementing the proposed method. Figure 2 shows the timing diagrams of the operation of the radio-acoustic device. Figure 3 shows the dependence of the sensing range R on the electromagnetic wavelength of the Doppler locator.

 A device for implementing the proposed method, according to figure 1, includes an antenna 1 made in the form of a combined radar-acoustic antenna EMAC (Fig. 1.8 [9]). In an EMAS antenna, a parabolic mirror is irradiated independently by sound and radio waves, and the optical axes of acoustic and radio emission coincide. For radio waves, the EMAC antenna is a Cassegrain two-mirror antenna and includes a horn irradiator, parabolic and wire reflectors, for acoustic waves, antenna 1 is a parabolic single-mirror antenna and includes an acoustic emitter and parabolic reflector. Antenna 1 has two inputs - radio frequency from the side of the horn feed and low frequency from the side of the acoustic emitter. The acoustic radiation pattern of antenna 1 is “embedded” in the electromagnetic radiation pattern.

 To implement this method in the antenna 1, in contrast to the prototype, a spark acoustic emitter is used, which can be performed, for example, in accordance with the description [14. Podolyan A.M. Broadband electrospark emitter for radio-acoustic sounding systems // Proc. doc. 7 All-Union Symp. on laser and acoustic sounding of the atmosphere. Part 2. Tomsk, 1982. S. 260-263].

 The radio-frequency input of the antenna 1 is connected to the antenna switch 2, which is connected to a nonlinear element 3, a low-noise amplifier 4, a reference driver 5 and a computer 6. A non-linear element 3 is connected to a microwave power amplifier 7 and a mixer 8, which is connected to the input of a low-noise amplifier 4. The reference frequency driver 5 is connected to the microwave power amplifier 7, to the computer 6 and the pathogen 9 connected to the acoustic emitter of the antenna 1. The mixer 8 is connected to the Doppler filter 10, which is connected to the band-pass amplifier 11. Computer 6 also connected to a non-linear element 3, the pathogen 9 and the strip amplifier 11.

 Antenna switch 2 can be performed on microwave switches Switches GaAs type KSWA-2-46 [15. RF / IF designer's guide, DG-98/99. 760 pg. Handbook microwave product data directory, EEM. Mini-circuits. USA P. 162].

 As a nonlinear element 3, a varactor can be used - a semiconductor diode, used as a nonlinear capacitance with low losses, included in the frequency multiplier circuit [16. Radio transmitting devices. Ed. M.V. Blagoveshchensky and G.M. Utkin. - M .: Radio and communications, 1982. 407 p. S. 244].

 Low-noise amplifier 4 is made, for example, as a device JS2-00100600-10-3a [17. Microwave journal euro-global editor. 1999. V. 42, 8. R. 19].

 The reference frequency driver 5 can be made in the form of a pathogen with a frequency synthesizer according to the digital indirect synthesis scheme [16, p. 351-352].

 As a computer 6 can be used by an IBM PC.

 As the microwave power amplifier 7, for example, a solid-state microwave amplifier of the LZY-2 type can be used [17, p. 107].

 The mixer 8 is made, for example, according to a balanced circuit in a solid-state design [15, p. 62].

 The pathogen 9 for the spark acoustic emitter can be made according to [14].

 The Doppler filter 10 can be performed according to the scheme of the comb of Doppler filters [1].

 Band amplifier 11 can be performed according to the active filter circuit [18. Horowitz P., Hill W. Art of circuitry. T. 1. - M .: Mir, 1983. 598 p. Fig. 4.17. The art of electronics. P. Horowitz, W. Hill. Cambridge University Press, 1980].

 The method is implemented as follows.

1. Based on the operator’s signal, the computer 6 generates signals to close the antenna switch 2, to start the reference frequency driver 5 and the exciter 9, which generates a series of electrical pulses during the time τ _s supplied to the input of the acoustic emitter of the antenna 1. The reference frequency driver 5 synchronizes the output exciter signal 9. The acoustic emitter of antenna 1 converts electrical pulses into sound ones, forming a packet of duration τ _s emitted by antenna 1 into free space. The probe volume of the acoustic packet is limited by the acoustic radiation pattern of antenna 1 and the value (τ _s c _s ) / 2.
The duration of one pulse in the packet is equal to τ _s0 , the pulse repetition period in the packet is equal to T _s0 (see the time diagram of the acoustic channel in figure 2).

 2. At the end of the radiation of the package of sound sounding pulses, the computer 6 sends a signal to stop the operation of the pathogen 9 and begins to work in the cycle of control of electromagnetic transmissions. The following operations are performed (see the time diagram of the radio channel in figure 2).

2.1. Computer 6 sends a signal to open the inputs of the antenna switch 2 from the side of the nonlinear element 3 and the radio frequency input of the antenna 1, and also to close the output of the antenna switch 2 from the side of the low-noise amplifier 4, sends a signal to the driver of the reference frequencies 5. The driver of the reference frequencies 5 sends a frequency signal F _e0 to the microwave power amplifier 7, which amplifies this signal and feeds to the nonlinear element 3. Nonlinear element 3 generates a broadband pulse signal with frequencies that are multiples of F _e0 ,
falling through the antenna switch 2 to the radio frequency input of the antenna 1, and a continuous broadband signal supplied to the mixer 8. Antenna 1 generates an electromagnetic pulse, the spatial distribution of which is limited by the electromagnetic radiation pattern of antenna 1 and the value (τ _e c _e ) / 2.
2.2. At the end of the electromagnetic pulse with a duration of τ _{e, the} computer 6 sends a signal to the antenna switch 2 to close the input from the side of the nonlinear element 3 and open the output of the antenna switch 2 from the low-noise amplifier 4. During the time τ _{g, the} echo signals pass through the antenna 1 and antenna a switch 2 to a low-noise amplifier 4, which amplifies these signals and supplies it to the mixer 8. The mixer 8 mixes the echo signal with the signal from the nonlinear element 3. The difference components of the signals from the output of the mixer 8 are fed It is coupled to a Doppler filter 10, where the signals of Doppler frequencies that are multiples of F _s0 are extracted and fed to a band-pass amplifier 11. The band-pass amplifier 11 separates the signals of multiple Doppler frequencies and feeds them to the computer 6.

2.3. During the time τ _{p, the} computer 6 processes the received echo signals in accordance with the algorithm defined by formulas (2) - (10).

2.4. At the end of the time interval τ _{p the} computer 6 sends a signal in accordance with claim 1, after which p. 2.1-2.3 are repeated N-1 more times.

3. After the time T _{s, the} computer 6 generates a signal in accordance with claim 1, after which p. 1, 2 are repeated.

Estimate the magnitude of the sensing ranges by the proposed method. For example, we substitute the values e = 18.4 mbar (which corresponds at T = 293 K relative humidity e / E = 80%, E is the partial pressure of water vapor at saturation, mbar), p = p ₀ , in the formula (6), we get f _p1 = 66189 Hz.

We take c _s = 340 m / s and, using formula (8), we obtain phase shifts Δφ _1max for the lower frequency F _s0 = 2000 Hz and one of the frequencies mF _s0 = 4000, 6000, 8000, 10000 Hz at the maximum for the frequency mF _{s0 of the} range R _max defined in [9, p. 123]. Given that the phase shifts can be measured using existing radioacoustic sounding equipment with an error of no worse than 0.5 ^o [19. Kushnir F.V., Savenko V.G. Electro radio measurements. -L.: Energy, Leningrad Department, 1975.367 s. S.312], we find the distances R at which the phase shift Δφ ₁ = 2 ^° for the same frequency pairs. The results are tabulated.

 The table shows that with multi-frequency radio-acoustic sounding of the atmosphere, receiving echo signals from different heights, it is possible to obtain phase shifts, which are reliably measured by modern equipment.

 Figure 3 shows the curves of the maximum and minimum ranges obtained by experimental installations of radio-acoustic sounding [9] (lines with circles and squares). From the maximum range curve, values were found in the third and fourth rows of the table. A line with triangles corresponds to the last row of the table.

Let us estimate the magnitude of the pulse durations. Let inclined radio-acoustic sounding be used at an elevation angle θ = 40 ^° . At a sounding height of H = 500 m, the inclined range R = H / sinθ = 778 m. Bearing in mind the ICAO requirement for a resolution in height ΔН = 30 m, we obtain a resolution in oblique range Δr = ΔH / sinθ = 47 m.
The air temperature range is set equal to ± 40 ^o C (T = 233 ÷ 313 K). From the Laplace equation we find the range of sound speeds
c _s = 20,053 • T ^1/2 = (306.09 ÷ 354.7) m / s
and the corresponding interval of sound frequencies F _s = c _s / λ _s = (1800-2086) Hz.

The duration of the acoustic sounding pulse τ _s = Δr / c _s = 140 ms is determined rounded for the middle of the range of sound velocities (c _s = 335.7 m / s). The acoustic package contains N _s = 276 wavelengths. To ensure the necessary range resolution, according to [9, file (4.26)], the condition N _s <[π / 2) λ _s γ _t / T] ^-1/2 = 334, where T = 293 K, γ _t = 0.0098 K / m is the dry adiabatic temperature gradient.

During the time between adjacent acoustic packages, each of them must cover a distance no less than the inclined sensing range, hence (T _s -τ _s ) ≥R / c _s . We get T _s ≥ 2.68 s or T _s = 2.7 s.

To determine the parameters of the pulses inside the acoustic package, we consider the spectrum of a periodic sequence of pulses. The lowest decay rate of the amplitudes of the first spectral components of the spectrum takes place for a rectangular pulse train. According to [20. Handbook of Electronics. T. 1. - M .: Energy, 1967. 640 s. P.102] the spectrum of a sequence of rectangular pulses of duration τ _s0 with a period T _s0 symmetrical with respect to the time axis is ruled, the frequencies are NF _s0 = N / T _s0 , where N = 1, 2 ... The envelope of the spectrum is described by the Bessel function, zeros which are located at the frequency points n / τ _s0 , n = 1, 2 ... Under the condition 1 / τ _s0 ≥ (M + 1) F _{s0, the} frequencies mFso, m = 1, 2 ..., M, have nonzero amplitudes, since they are in the same (main) lobe of the Bessel function. For the frequency MF _s0 = 10 kHz chosen above, we obtain a pulse duration of no more than τ _s0 = 83 μs.

The follow-up period of the radio pulses T _{e is} found from the condition of normal phase detection of reflected pulse signals: a discrete function (with a Doppler frequency equal to the sound frequency) should be represented by more than two samples for the follow-up period. Therefore, 1 / T _e > 2MF _s , we take 2MF _s = 20 kHz, then we can take 1 / T _e = 25 kHz, i.e. T _e = 40 μs. The duration of the sending τ _e is determined from the condition that it overlaps the resolution distance, i.e. c • _e τ _e = ΔR, where we find τ _e = 47/3 • August ¹⁰ = 0.16 microseconds. The time between adjacent radio pulses T _e -τ _{e is} distributed between the time of reception of the reflected radio pulse τ _g = 2R / c _e = 5.2 μs and the time for data processing τ _p = 34.64 μs. During the time between two adjacent acoustic packages, one can radiate N = (T _s -τ _s ) / T _e = 64000 radio pulses.

 Thus, the proposed method due to the new operations specified in the claims, allows to eliminate the disadvantages of the prototype, solves the problem and ensures the achievement of the necessary technical result.

Claims (1)

The method of radio-acoustic sounding of the atmosphere, which consists in sending a packet of acoustic vibrations to the atmosphere from the Earth’s surface, accompanying the packet with radio pulses from the Doppler radar, receiving echo signals when the Bragg condition λ _s = λ _e / 2, where λ _s , λ _e - the length of the acoustic and electromagnetic waves in the reflection region, the characteristics of the echo is determined height profiles of temperature and humidity, characterized in that the package of the acoustic oscillations of duration τ _s are composed of a pulse duration w τ _s0 a repetition frequency F _s0, τ _s0 <1 / MF _s0, accompany packet radio pulse duration τ _e, a frequency spectrum which are _e0 mF, where m = 1,2,. . . M, and the frequency F _e0 is related to the frequency F _{s0 by the} relations λ _s = λ _e / 2, where λ _e = c _e / F _e0 ; c _e is the speed of light; λ _s = s _s / F _s0 ;

- the speed of sound in air at a temperature T lying in a predetermined range from T _min to T _max , receive echo signals at frequencies close to mF _e0 , measure the characteristics of the echo signals, namely the values of the frequencies of Doppler displacements F _d1 , F _d2 , . . . , F _dM for different ranges and the phase difference of the signals at different Doppler frequencies, the moisture profile is determined from the phase difference for the entire sensing distance, the altitude temperature profile is found from the frequencies of Doppler shifts taking into account the humidity values.

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