RU2693842C1 - Method for probing the ionosphere and troposphere - Google Patents

Abstract

FIELD: geophysics.

SUBSTANCE: invention relates to geophysics and is intended for monitoring of natural environment, information support of radio communication and navigation. Information obtained from radio markers is easily integrated into the existing ionosphere monitoring system and enables to expand the probing area of the ionosphere and the troposphere over oceans and hard-to-access regions of the Earth. In the algorithm for calculating characteristics of tropospheric refraction, a scheme is proposed for calculating integral moisture content in the atmosphere and profiles of moisture in the atmosphere.

EFFECT: technical result consists in probing the outer ionosphere from low orbits of spacecraft used in the proposed scheme, and provides higher efficiency and efficiency of monitoring the ionosphere and troposphere.

1 cl, 4 dwg

Description

The claimed method of sounding the ionosphere and the troposphere relates to geophysics, and is intended for monitoring the natural environment, providing information for radio communications and navigation, and studying the effects of solar activity.

The known technologies of sounding the ionosphere are based on the interaction of electromagnetic radiation with the ionospheric plasma. The sounding schemes of the ionosphere provide for the emission of a radio signal into the ionosphere and its reception with subsequent analysis of changes in phase, frequency and time characteristics.

According to the position of the source of the sounding signal, the sounding technologies of the ionosphere can be conditionally divided into surface (“bottom-up”) and satellite (“top-down”, this includes radio-dark sounding). Bottom-up sounding is usually implemented over land and is usually limited to the heights of the main F2-layer of the ionosphere. To monitor the ionosphere over the oceans, satellite sensing technologies and models of the ionosphere are commonly used. At the same time, the requirements of the World Meteorological Organization for monitoring the ionosphere are not achievable. Installing ionospheric sounding stations on ships, as an attempt to solve this problem, is a difficult technical problem, and the results of such sounding are not profitable. New technical solutions are needed.

All technologies of sounding the ionosphere use physical bases that determine the change in the characteristics of radio signals in the ionosphere and in the troposphere due to a decrease in the phase velocity of radio waves and the polarization of water vapor molecules in the Earth’s magnetic field [1]. The phase shift during signal propagation in a non-ideal medium is determined by the length of the signal propagation path L between the receiver and transmitter and the refractive index of the medium n [2]:

, (1)

, (one)

where, ϕ is the phase incursion for the operating frequency f of the signal, n _l is the refractive index of the signal along the signal path, ϕ ₀ is some unknown initial phase of the signal, and c is the speed of light.

In the ionosphere, if we neglect the small influence of collisions of particles of the medium and the magnetic field [1, 2]:

, (2)

, (2)

where n _e is the local electron concentration.

In the troposphere, the refractive index of radio waves does not depend on the frequency [1, 3]:

n ^Tr = 1 + K ₁ (P - e) / T + K ₂ e / T + K ₃ e / T ² , (3)

where K _1-3 - empirical coefficients,

P - atmospheric pressure

T - air temperature, K,

e - partial pressure of water vapor, Pa.

Taking into account the refractive indices of radio waves in the ionosphere, estimates of the delays of received signals and the coordinates of the receiver and transmitter on the spacecraft, solutions are proposed in RF patent No. 2042129 “Ionospheric probe”, RF patent for useful model No. 76462 by RF application 201010505905 dated February 19, 2010 for hardware -program complex of ionospheric monitoring, and for probing the characteristics of the tropospheric delay - in [3]. The disadvantages of these solutions are taken into account in patent No. 2502080 [1], where a method for sounding the ionosphere, troposphere and geo-motions using the “top-down” scheme is proposed based on data received from the network of GPS / GLONASS / Galileo navigation receivers, ground-based and space-based ionosonde data , consideration of tropospheric delays in the characteristics of GPS / GLONASS / Galileo signals and signals from geostationary spacecraft, errors in the calculations of charged particle concentration profiles and relative PES estimates, quality of the ionosphere and troposphere models, verification and shaft identification of algorithms, control and verification of the equipment proposed for use. However, [1], as the main prototype of the proposed method of sounding the ionosphere and troposphere, but according to the top-down radio sounding scheme, is characterized by information redundancy, and the sounding of the ionosphere and troposphere is not a GNSS problem, therefore ground-based receiving equipment of GNSS signals — navigation receivers used in the scheme of sounding the ionosphere is not for its intended purpose, roads, require sophisticated software and significant maintenance costs. Alternatively developed specialized projects of space systems for sounding the ionosphere are not cost-effective and also use a top-down sounding scheme.

In order to increase the profitability of sounding the ionosphere, especially over the vast expanses of the oceans, it is advisable to use a bottom-up ionosphere radio-sounding scheme with a source of radio signals transmitted through the ionosphere (hereinafter referred to as a radio marker) at the Earth's surface or in the atmosphere and a receiver of signals with an antenna on spacecraft. The proposed sensing scheme is shown in FIG. 1, where:

1 ₁ ... 1 _k - grouping of spacecraft that receive signals of radio markers through on-board antenna devices;

2 ₁ ... 2 _n - surface radio markers with antenna device and power supply unit;

3 ₁ ... 3 _n - stations for receiving, processing and transmitting satellite data;

4 - ionosphere layer;

5 ₁ ... 5 _i - spacecraft of GNSS and geostationary spacecraft, which can also be equipped with receivers of radiomark signals.

The radio marker must be equipped with a power supply and an antenna, a chroniser, which is generally orders of magnitude cheaper than the professional geodetic receivers used in the prototype. This brings the radio marker to the category of consumable tools, which is especially important for large and inaccessible areas. The body of the radio marker must ensure the safety of the power supply unit, the calculators and antennas from the effects of the natural environment.

Antenna devices for receiving radiomark signals are one or more antennas with a low-noise amplifier (LNA), an adapter for connecting to a high-frequency cable, through which LNA power is also provided. According to the level of the received signal, pre-filtering of the received signals occurs, for example, on the transition from the sleeping to the operating mode of the sounding circuit, their subsequent identification and control of the completeness of the code received sequences. At installation of antennas the review in the chosen sectors is provided.

A distinctive feature of a radio beacon - a source of time-synchronized signals - is an identification index stitched in the structure of its signals. The delay of the index code sequence received by the receiver on the spacecraft at at least two frequencies (f ₁ and f ₂ ) makes it possible to estimate the concentration of charged particles in the ionosphere PES = I ₀ [1] along the sounding trajectory in accordance with (2):

(4)

(four)

where L ₁ is the phase rotation frequency of the radio beam at the frequency f _{1 of the} received signal with the wavelength λ ₁ = c / f ₁ , const ₁ and σL ₁ are constants.

L ₁ λ ₁ and L ₂ λ ₂ can be replaced by the corresponding values of the pseudorange estimates to the receiver on the spacecraft.

Constants are estimated as a result of experiments, can be specified in technical documentation, calculated using the ionosphere model, according to reference signals, according to land and space ionosondes.

For the calculation of the TEC in the vertical column, a correction to the slope of the visible spacecraft is necessary:

, (5)I ^zenith (t, φ, λ) = I ₀ (t, φ, λ)

, (five)

where α is the zenith angle of the direction to the spacecraft, H _ionosphere is the height of the ionospheric layer (which is usually specified under the assumption of a thin layer), R _З is the radius of the Earth, t is the time, ϕ is the latitude, λ is the longitude of the radio marker.

The radio-transmission of the ionosphere in the proposed method is possible at the same frequency, but this is more difficult in terms of information and reduces the efficiency of obtaining the final results of sounding. In addition, the pseudo-ranges (instantaneous distance estimates) between the radio marker and the receivers on the spacecraft, calculated by the single-frequency scheme, are very noisy. Therefore, to obtain adequate estimates, long-term analysis of the received signals is necessary, which is critical for the operational sounding of the ionosphere, given its rapid variability.

To improve the accuracy of determining PES, it is necessary to use signals at at least two separated frequencies, large angles of radiation of radiomark signals, average additive or average geometric estimates of PES, or a combination of the frequencies used in calculations and visible receivers on the spacecraft in the radiation zone of the radio marker.

One of the traditional solutions for providing the chronization function (time sensor), including for the proposed sounding of the ionosphere and troposphere, is, for example, the exact timing technology of the Global Navigation Satellite Systems (GNSS). Their spacecraft can also be used to house receiving equipment for radio marker signals. However, as the calculations showed, the use of the orbits of these spacecraft, as well as at geostationaries, increases the required radiation power of the radio marker to 15–20 W, compared to the use of low-orbit spacecraft sensing in the scheme, where, for example, to transmit mobile satellite communications to orbits of the “Gonets” type, the power of the surface radio marker is about 1 W. The consequence of increasing the radiation power is a decrease in the autonomy of the radio marker provided by electric energy from batteries and / or solar batteries.

Receivers on the spacecraft, receiving signals from subionospheric radio markers through antenna devices, form a stream of information in the spacecraft's onboard receiver-calculators with subsequent retransmission of the results obtained through the onboard communication systems, data storage and transmission to the receiving and processing points, or through geostationary spacecraft, for example, in the “Ray” system. The multi-frequency navigation receivers of GNSS signals installed on the spacecraft allow solving the problem of sounding the external ionosphere and eclipsing sounding.

It should be noted that the top-down sounding scheme in [4] proposed options for using polar ionospheric spacecraft in highly elliptical orbits with onboard ionosonde to monitor the polar ionosphere, which, according to the authors, should potentially ensure the greatest accuracy in determining the basic parameters of the ionosphere ( f ₀ F2, h _m F2), since the critical frequency gives an improvement in the results of adaptation of the international ionosphere model (IRI) by 30-60% compared with the long-term forecast. In [5] stated that the parameter h _m F2 can provide an increase of 15-20%, MUF on average up to 40%, PES - on average up to 30%. However, given the size of the Fresnel probing signals in this sounding scheme from highly elliptical orbits, ignoring the morphostructural features of the polar ionosphere and its variability, the transition from the climate model of the ionosphere IRI to the adaptable quality ionosphere model SIMP2 The ionosphere can be attributed to populist.

The main drawback of top-down sensing options is the significant energy potential of the channel and the difficulty of interpreting external sensing ionograms (SVZ) from high orbits, especially for the heterogeneous and non-stationary polar ionosphere. At the same time, its morphology is ignored. It is proposed to remove the restriction on the channel-sensing energy through the use of complex signals and their accumulation during an SVZ, or through the use of trans-ionospheric sounding (SIZ). But this complicates the sensing technology, since the acquisition of SVZ ionograms is energy-intensive, which is critical for the power supply of the spacecraft, in addition, difficulties arise in electromagnetic compatibility (EMC) on board the spacecraft, which, when accumulating complex signals, significantly extends the sensing session, thereby reducing the efficiency monitoring of the ionosphere.

When receiving signals from a ground-level radio marker on the spacecraft, the channel’s power is provided by a ground-based transmitter; in addition, no complex signals are required. Passive receiver does not violate the requirements of the EMC, simplifies the "binding" of the receiver chronizer in time and ephemeris, the characteristics of received signals can be transmitted through official communication channels. In addition, when limiting the frequency range more than the cutoff frequency of the signal by the ionosphere, the dimensions of the receiving antenna are reduced.

The technical result of the claimed method is to increase the profitability and efficiency of monitoring of the ionosphere and troposphere.

Radiomark radio signals are code modulated carrier frequency. The code provides for service tags, radio marker index labels, additional data from the output of the radio marker's calculator. Signals are synchronized in time at separated discrete frequencies. From the difference in arrival time associated with the chroniser service marks, which may be associated with the index of the radio marker, the code and phase delays of received signals used in further calculations of the state of the ionosphere and troposphere are calculated. It is possible to transfer the index of a radio marker on one frequency, and on the other additional data from the output of the radio marker's calculator.

The radiation of the radiomark signals is oriented to the upper hemisphere or to the cone in it, in accordance with the results of the calculation of the radiation characteristics and the type of antenna.

The penetration of the spacecraft receiver into the radiomark radiation cone is a necessary condition for the probing of the troposphere and ionosphere. The geographical binding of the beacon with modern GNSS service is not difficult. At the same time, the presence of a GNSS signal built into the radio marker of the receiver allows the functions declared in the prototype to be implemented, and the calculated arrival time of the GNSS signals received via the antennas is transmitted through controllers to the radio marker data storage system and data transmission to the spacecraft.

The onboard spacecraft QA (receiver) calculates the arrival time of radiomark signals received via antennas and time synchronized radiation, and transmits delays of received signals through controllers to the onboard data storage and transmission system. The data transmitted from spacecraft are received at ground information receiving and processing centers or via geostationary spacecraft and are used to prepare specialized information products. The position of the spacecraft relative to the beacon is calculated on the basis of motion models, or according to the data of the specialized distribution.

The proposed method greatly simplifies data processing, since the transmitted data contains the identifier of the radio marker and the signal delay time at a set time, and when using the built-in GNSS receiver in the radio marker, data on the state of the ionosphere and troposphere can be transmitted. Compared to the volume of a conventional GNSS telegram used in the prototype, the savings in the amount of information transmitted and processed can reach two orders of magnitude.

The information obtained is easily integrated into the existing ionospheric monitoring system. And in the case of using autonomous radiomarkers, it can expand the territory of sounding over the oceans and hard-to-reach areas of the Earth.

The on-board receiver of radiomark signals on the spacecraft must be configured to receive the main operating frequencies of the radiomark and be powered by an onboard network or an autonomous source. Radiomarker signals are received by antenna devices, amplified, filtered, and fed to the receiver's electronic board, where signals are amplified, filtered, and converted into a digital code. The receiver of the radiomark signals provides automatic continuous real-time determination and issuance of delay estimates of received signals in the established format, the possibility of accumulating data and transmitting them via dedicated lines to the on-board data transfer system.

An example of the calculation of the energy potential of the communication channel Pv during the fire protection system for orbits with a height of 10 to 40 thousand km is shown in FIG. 2 [6].

Calculations confirm that the signal exceeds the interference up to 6-10 dB for distances between the receiver and the radio marker exceeding 40,000 km. But for the implementation of this scheme requires a significant power of radiation pulses. For example, in the decameter (HF) range - up to 10 - 20 kW per pulse. This is critical for the EMC KA. Therefore, to reduce the power of the radiation source, frequencies of hundreds and thousands of MHz are used.

The realities of the basic “bottom-up” sounding method on spacecraft used in the proposed method can be confirmed by the results of long-standing experiments on sounding the ionosphere with the spacecraft Intercosmos-19 according to the top-down scheme. But this large-scale experiment was no longer repeated, including due to problems with EMC (proven when attempting to install an ionosonde on the ISS) and high energy costs.

The trend of using the GHz band to reduce the power of the radiation source is confirmed by the calculations of the coupling characteristics presented in FIG. 3 for ground-based power of 1 W and frequencies of 250 MHz (for characteristics close to the requirements of the Gonets spacecraft repeater), 1000, 1500 and 2500 MHz (for telemetry conditions).

Modulation of pulse code modulation based on phase modulation with a 20 kHz emission band and a receiver noise figure of 2.5 dB is assumed. Losses in the atmosphere, including the ionosphere - 0.01-0.1 dB. The calculations used the assumption of antennas - dipoles with 2 dB radiation loss and 3 dB of polarization, and spiral-conical antennas with a gain of 12 dB and a polarization loss of 0 dB.

Thus, even with the simplest antennas and the transmitter power of a 1 W surface radio marker, it is possible to communicate with the spacecraft at selected frequencies up to an altitude of 1000 km. The necessary margin for channel power is about 20 dB obtained with improved antennas. But it is more expensive.

Multi-frequency radio-sounding of the ionosphere makes it possible to almost completely level out the ionospheric error and to obtain an estimate of the tropospheric delay of the probed signals, independent of their frequency. The delay of the radio signal associated with the passage through the tropospheric layer can be determined by the formula [1]:

L_тр=

, (6)

L _tr =

, (6)

L_тр - пространственная или наклонная задержка сигнала в тропосфере, м, Where

L _mp - spatial or oblique signal delay in the troposphere, m,

L - distance to the satellite, m,

l - path along the path of the radio beam in the troposphere, m,

n ^Tr is the refractive index of radio waves in the troposphere (3).

To calculate the refractive index of radio waves in the troposphere, weather data and atmospheric reference models are used. Usually, the averaged n ^{Tp is} the refractive index of radio waves at the earth's surface, which is used when estimating the total correction of tropospheric refraction. Based on the calculated values, the characteristics of the tropospheric refraction of the radiomark signals are calculated to correct the obtained TEC estimates in the ionosphere.

In the calculations, an additive representation of the density of air from the density of its dry part and the density of water vapor (ρ = ρ _с + ρ _p ) is usually used:

n ^Tr = 1 + K ₁ ρ _with + K ₂ R _p ρ _p + K ₃ R _p ρ _p / T, (7)

where R _c = 287.0538, J / (kg K), R _p = 461.526, J / (kg K) are universal gas constants of dry air and steam, K _1,2,3 are coefficients [1-3].

The “dry” part of the tropospheric delay is about 90% of the total tropospheric delay. The “wet” part depends on the properties of the air mass and its moisture content. The “dry” part of the tropospheric delay is quite accurately determined by weather data, radio sounding data of upper-air stations near the receiver, as well as using the hydrostatic law (dP = ρ _with gdz) of decreasing pressure (P) with height. Models of standard atmospheres can be used in calculations, for example, in calculations of the attenuation of radio signals in atmospheric gases on Earth-to-space routes. Pressure, temperature and humidity models are used in cases where reliable measurement data are not available.

In the troposphere [2, 7, 8]:

L_тр = ZTD m(α) + (G_n cos(A) + G_e sin(A)) m_G(α), (8)

L _mp = ZTD m (α) + ( G n cos (A) + G e sin (A)) m G (α), ( 8)

where ZTD is the zenith tropospheric delay [m], G _n and G _e are the north and east gradient parameters [m], m and m _G are the mapping functions, A and α are the azimuth and satellite zenith angle.

The hydrostatic part of the delay (ZHD) is often determined using analytical models, among which the Saastamoinen model is actively used [9]:

, (9)

, (9)

where K ₁ = 77.60, K / hPa in (3); R _d = 287 J⋅kg ^-1 ⋅K ^-1 - specific gas constant of dry air; P _s - surface pressure at the station, hPa; g ₀ = 9.784 m / s ² - acceleration of free fall in the center of mass of the atmospheric column at the equator; B and H - latitude (hail) and altitude (km) of the station.

The difference between the zenith tropospheric delay and the hydrostatic component allows determining the wet component ZWD of the zenith tropospheric delay, which is converted into an integral moisture content in the atmospheric column (IWV, mm) [10-12]:

, (10)

, (ten)

where ρ _w = 1000 kg / m ³ is the density of liquid water; R _w = 461.5 J⋅kg ^-1 ⋅K ^-1 is the specific gas constant of water vapor; K ₂ = 71.2952 K / hPa, K ₃ = 375463 K ² / hPa; T _m is the temperature of atmospheric column ( ⁰ , K) weighted by the elasticity of water vapor. The latter is determined using a regression expression with data of the surface temperature T _s ( ⁰ , K) [13]:

T _m = 50.4 + 0.789T _s . (eleven)

The estimated accuracy of the ZTD estimates obtained in this way for a number of areas, based on the MSE of residual differences, is about 1.5 mm. Taking into account the accuracy of the models for ZHD and T _m , the accuracy of IWV is estimated to be approximately 0.55 mm of precipitated water [14].

To verify the calculation algorithm and the obtained IWV estimates, experiments were used in Nalchik [14] (mainly for heavy rainfall) and experiments in Kazakhstan in the area of the Baikonur cosmodrome. To verify the obtained results, a comparison was made with the data on the integral content of water vapor NCEP / NCAR of the National Oceanic and Atmospheric Administration (NOAA, USA) and the ERA-Interim European Center for Medium-Term Prediction. In this case, linear interpolation of the IWV values from the four grid nodes closest to Baikonur was performed.

FIG. 4 shows an example of calculation results for 3-6.12.2010. Other experiments have shown a similar overestimation of the integral moisture content in the atmospheric column according to foreign centers, but this is a known fact [15]. The geomagnetic situation in the indicated time intervals was calm. Solar flares were not.

In addition, the data of foreign centers do not meet the requirements of the World Meteorological Organization for the accuracy of determining IWV (10%) [16]. And the software used [12-14] needs some work for the mobile sensing version.

When solving the inverse problem of probing, it is possible to obtain humidity distribution profiles for height and space using data on the characteristics of GNSS signals, for example, based on GOST 26352-84 (with 2017 clarifications), which determine the model of humidity in the Northern Hemisphere. The humidity model in GOST 26352-84 is presented from sea level to an altitude of 10 km according to several characteristics. The humidity characteristics of the standard comply with the international standard ISO5878 / D-2. For calculations in the southern hemisphere of the Earth, it is necessary to form adaptive models of the humidity profile, use known models, for example, the well-known model A.Kh. Hrgiana with an exponential decrease in humidity with height in the troposphere. Such models make it possible to form an initial approximation for an iterative selection of the conformity of the IWV value obtained in the calculations and the integral of moisture content according to the GOST 26352-84 model. This is the task of receiving and analyzing centers for sounding the ionosphere and the troposphere.

To restore the profile changes in height n (h) for a series of measurements of the signal delays form a system of equations:

A=Y, (12)X

A = Y, (12)

L, where Y is the matrix of measurements of signal delays along the path of the radio beam in the troposphere with elements

L,

X is the matrix of the refractive index in the troposphere with elements (n _i-1 ) in layers (the approximation of the spherical symmetry of the layers is usually used),

A is the operator of the direct problem or the transformation matrix (the kernel of the equation, for example, in the form of a Kalman filter [17]), with the elements:

z_iw_i/

, (13)a _ij =

z _i w _i /

, (13)

where w _i - quadrature weights on the i-th level,

R is the radius of the Earth, m,

- угол места приемника на КА; м;

- elevation angle of the receiver on the spacecraft; m;

n ₀ is the generalized refractive index of radio waves along the entire route and at the earth's surface.

Elements (13) can be calculated using the method of conjugate gradients or by constructing an autoregression equation. In this case, the inverse ill-posed problem of atmospheric refraction is solved, which has an approximate solution on the basis of the mathematical apparatus for solving Fredholm integral equations of the first kind [17, 18] and finding a finite-dimensional vector that minimizes the functional:

, (14)

, (14)

- искомая совокупность приближения оператора и функции некоторого приближения

по некоторой трассе наблюдаемого КА с приемником сигналов радиомаркеров. Where

- the desired set of approximations of the operator and functions of some approximation

along some route of the observed spacecraft with a receiver of radiomark signals.

должна при минимизации погрешности δ обеспечивать лучшее приближение к точному решению задачи:

. Sought set

when minimizing the error δ, should provide a better approximation to the exact solution of the problem:

.

From the restored n (h) profile, the vertical air humidity profile and the vertical air density profile can be calculated using the assumption of a polytropic model of the atmosphere, where the temperature decreases with a linear law and the atmospheric pressure decreases according to a barometric law.

When solving the inverse problem of determining the desired vector X (profile of the refractive index n (h)) according to the data of the radio signal delay, the statistical regularization method can be used. The solution is also obtained as a result of the iterative process:

A+

]^-1A^T

[(y-y_s-1)-А(x_b -x_s-1)], (15)x _s = x _b + [A ^T

A +

] ^-1 A ^T

[(yy _s-1 ) -A (x _b -x _s-1 )], (15)

where x _b - the initial approximation of the vector X,

L, К_у =

I, I - единичная матрица,

- дисперсия ошибок измерений

L_тр, K _y - the matrix of measurement error values

L, K _y =

I, I is the identity matrix,

- dispersion of measurement errors

L _tr ,

s is the iteration number,

R _x - matrix of values of inter-level correlation (stabilization) of the refractive index of radio waves:

R_Т +

R_Р +

R_е , (16)R _x =

R _T +

R _P +

R _e , (16)

where R _T , R _P , R _e are the covariance matrices of temperature, atmospheric pressure and air humidity [18].

For the initial approximations in the absence of upper-air data, you can use the relative humidity profile based on GOST 26352-84 (with 2017 clarifications).

The accuracy of solving the inverse problem depends on the quality of the assignment of the correlation functions.

Another way to restore vertical profiles is associated with the use of a variation method. At the same time, it is necessary to find such a vector X, at which the minimum of the loss function is reached as in (14):

(X)=0,5(X—X_b)^T

(X—X_b)+0,5(Y—АX)^T

(Y-АX), (17)

(X) = 0.5 (X — X _b ) ^T

(X — X _b ) +0.5 (Y — AX) ^T

(Y-Ax), (17)

where X is the estimate of the state profile of the atmosphere [19].

To implement this method, a large archive of actually observed vertical refractive index profiles is also required.

The restored vertical profile of the refractive index can restore the humidity profile, for example, by setting the vertical air temperature profile. The vertical distribution of atmospheric pressure can be obtained from the assumption of a hydrostatic air density profile. These questions were not considered in [20].

A series of long-term observations of the characteristics of radiomark signals and the resulting TEC estimates, corrected for tropospheric refraction errors, can be used to restore the vertical electron concentration profiles in the ionosphere (n _e (h)) based on solving the inverse ill-posed problem of atmospheric refraction. A set of vertical profiles can be interpolated into a vertical section of the probed characteristics of the ionosphere and troposphere.

The solution of the problem of finding a finite-dimensional vector that minimizes the functional is chosen as the basis of the technology for solving the inverse problem of radio echoing:

, (18)

, (18)

- искомая совокупность приближения оператора и функции некоторого Where

- the desired set of approximations of the operator and functions of some

по трассе

для наблюдаемого приемника на КА, погрешностью δ и условием:

. approximations

on the highway

for the observed receiver on the spacecraft, the error δ and the condition:

.

The initial approximation of the charged particle concentration profile is set from climate models of the ionosphere, which need to be adjusted for a specific region. In the subsequent approximations, an iterative procedure is implemented using previous profiles. When forming the initial approximation, the tropospheric delay is taken into account. If incorrect simulation results appear in the calculations, filtering of the results by previous approximations is provided. In addition, the calculated profiles are averaged, which increases the stability and reliability of the calculations. To improve the accuracy of sensing, a regional model of the ionosphere is needed based on observational data.

Software for the implementation of the proposed method, it is advisable to perform server applications and communication networks based on Internet communication, fiber, radio links. The software package for restoring the electron concentration profiles in the ionosphere from radiomark signals and tropospheric delay characteristics should include thematic program blocks for:

1. Management and planning of signal reception;

2. Identification and control of the completeness of code sequences in the received signals;

3. Evaluation of the characteristics of received signals;

4. Calculation of the total electron concentration in the ionosphere and the field of distribution of the total electron content in the ionosphere;

5. Calculation of the field of distribution of the integral moisture content in the atmospheric column;

6. Formation of a matrix of initial and model approximations of the concentration profile of charged particles in the ionosphere, the vertical air humidity profile and the vertical air density profile in the troposphere above the sensing point based on a regional atmospheric model;

7. Formation of regional models of ionospheric and tropospheric characteristics and archives;

8. Calculation of profiles of humidity and density in the troposphere;

9. Construction and analysis of graphs and maps;

10. Diagnostics of anomalies in controlled characteristics;

11. Output to the display device of the results of the sounding of the ionosphere and troposphere.

A simplified algorithm for the radio sounding of the ionosphere and troposphere is that the radio marker signals are received using an antenna device on a spacecraft that includes one or more antennas. The spacecraft can also be equipped with GNSS signal receivers. At the antenna output, the received signals of the radio marker and from the GNSS satellite are amplified, filtered, converted into a digital code and presented in the established format for further processing. The signal-to-noise ratio value is compared with the threshold value; if it is less than the specified one, then after a set delay time, the receiving antennas are switched to the standby mode of the new task. For airborne receivers, antenna control can be implemented by commands via a satellite data receiving / receiving station or automatically by a received radio marker signal. Received signals are identified by arrival time, code indices, and frequency. This information is transmitted to ground information receiving and processing points, where visible spacecraft with receivers are filtered by their position above the horizon and relative to the zenith, the effects of tropospheric refraction are calculated, and PES estimates, charged particle concentration profiles in the ionosphere, followed by filtering, averaging, archiving and mapping results.

In terrestrial data receiving and processing points, measurement arrays are formed in real time to restore PES estimates, charged particle concentration profiles in the ionosphere, and the characteristics of the tropospheric delay of radio marker signals. For the initial approximation of the reconstructed profiles in solving the inverse problem of modeling, data from the ionosphere model, the troposphere with operational correction based on the results of meteorological and upper-air observations, the results of previous calculations, and profiles obtained during radio sounding of the atmosphere with terrestrial and cosmic ionosonds are used. After conducting iterative approximations and checking the obtained results for compliance with specified errors, filtering, averaging, representation,

archiving and mapping of the results, as well as analysis of emissions, trends, including coordinates of receiving antennas.

With the additional installation of a GNSS signal transmitter in the radio marker at at least two frequencies, the sounding circuit of the ionosphere and troposphere is used according to the prototype used with the transmission of the received data in the structure of radio signals to the spacecraft.

The installation of GNSS signal receivers on the spacecraft in the proposed sensing scheme makes it possible to probe the characteristics of the external ionosphere and to perform radio occultation sounding of the atmosphere in the presence of an antenna complex with antenna orientation to the horizon.

The proposed method can be implemented in a mobile or in a stationary variant with respect to a radio marker.

List of drawings

FIG. 1. Sounding scheme: 1 - spacecraft with receivers, 2 - radio markers, 3 - information receiving and processing points, 4 - ionosphere, 5 - GNSS spacecraft and geostationary spacecraft.

FIG. 2. The change in the energy potential of the communication channel Pv at the otis for the orbits in height from 10 to 40 thousand km. The red line is for the frequency of 5 MHz, the green line is for the frequency of 10 MHz, the blue line is for the frequency of 15 MHz, the blue line is for the frequency of 20 MHz, the dotted curve shows the level of interference from the broadcast transmitter of 21 meter range with a power of 50 kW at spacecraft altitudes.

FIG. 3 Estimates of the energy communication channel for two types of antennas on the Earth in spacecraft orbit for signals of a surface radio marker with radiation power of 1 W. The abscissa axis is the removal (km), the ordinate is the Signal / Noise ratio (dB). (o) - frequency 250 MHz, (+) - 1000 MHz, (x) - 1500 MHz, (-) - 2500 MHz.

The left fragment for the antenna gain on the Earth and on board is 12 dB (directional spiral), the losses in the feeders are 1 dB, the polarization losses are 0 dB:

The right-hand fragment for antenna gain on the ground and on board is 2.1 dB (directional dipole), feeder losses 1 dB, polarization losses 3 dB.

FIG. 4 Results of the calculation of the integral moisture content in the atmospheric column using GNSS signals and data from foreign archives.

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Claims (2)

1. The method of sounding the ionosphere and troposphere, consisting in radiation into the ionosphere and troposphere of sounding radio signals synchronized in time at at least two frequencies, receiving radio signals through an antenna device, analyzing changes in phase, frequency and temporal characteristics of received signals used to calculate the parameters of the ionospheric plasma , the calculation of the tropospheric delay of the received signals and its transformation through analytical models into predictive profiles of atmospheric characteristics with initial approximations and weather, climate and analytical atmospheric models, characterized in that the radio source is located on the surface of the Earth, ocean, ice, or in the Earth’s atmosphere; radio signals are received through antennas on spacecraft; the radio signal contains an identification index associated with the coordinates of the signal source , the calculation of the integral moisture content of the atmosphere is carried out according to the estimated tropospheric delay of received signals using analytical, climatic and regression these models. 2. A method of sounding the ionosphere and troposphere according to claim 1, characterized in that the signal source is connected to at least two frequencies of each of the used GNSS signals with a radio source and transmitted data in the structure of radio signals to spacecraft whose onboard multi-frequency navigation receivers of the GNSS signals are used for sounding the outer ionosphere.

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