WO2010114413A1

WO2010114413A1 - Method and device for remotely probing the earth with the aid of a multi-station radar system

Info

Publication number: WO2010114413A1
Application number: PCT/RU2009/000337
Authority: WO
Inventors: Вячеслав Филиппович ФАТЕЕВ; Сергей Алексеевич ПОПОВ; Александр Владимирович КСЕНДЗУК
Original assignee: Открытое Акционерное Общество "Межгосударственная Акционерная Корпорация "Вымпел"
Priority date: 2009-03-31
Filing date: 2009-07-06
Publication date: 2010-10-07
Also published as: RU2009111512A

Abstract

The invention relates to radiolocation and can be used in systems for remotely probing the Earth from mobile carriers. The invention has the technical result of increasing the efficiency with which radio images of the Earth's underlying surface are obtained, and simplifying the corresponding device. A region of the Earth's surface is irradiated with orthogonal probing signals from N transmitters simultaneously, the reflected signals and the direct propagation signals of the transmitters are received and information about the state of each transmitter, the carrier thereof and the propagation medium is extracted. M non-overlapping independent directional pattern beams oriented towards the Earth's surface are formed in the antenna systems of each receiving station. The reflected transmitter signals are divided and summed over power, and radio images of the Earth's surface are generated in the form of the distribution of radio brightness. The radio images are superimposed on a digital map of the locality and the coordinates of points exhibiting high brightness are determined. The device comprises a transmitting and receiving station which consists of a weakly directional antenna, an antenna system, reflected navigational signal receivers, power value sequence generators, complete radio image generators, a device for displaying current radio images, a device for storing a digital map of a locality, an aircraft altitude, pitch and roll sensor and the navigation equipment of the customer.

Description

Method for remote sensing of the Earth using a multi-position radar system and device for its implementation

(i) Area of use

The invention relates to the field of radar and can be used in remote sensing systems of the Earth from mobile carriers.

(ii) Prior Art

A known method of remote sensing of the Earth using an aircraft multi-position synthesized aperture radar system (MPA PCA) (see Radar stations for Earth observation / edited by G.S. Kondratenkov. - M .: Radio and communications, 1983, 272., page), using one transceiver and two receiving positions. Such PCA MPs are used in practice, however, they do not have the speed of recording, since in order to obtain an image of a site, it is necessary, firstly, to record the radio hologram of the reflected signal, secondly, to deliver its processing point and, thirdly, to synthesize the radio image. Therefore, such PCA MPs are not used for on-line survey of the Earth's surface.

The closest in essence to the claimed invention (prototype) should be considered the method of remote sensing of the Earth, described in patent N "2278398 with priority dated July 6, 2004. (authors Sakhno I. B., Fateev B. F.). The method is implemented using N transmitting and one receiving position. 1. N independent orthogonal signals Si .... S _N are emitted from the board of N transmitting positions (Rx).

2. Orientation patterns (ND) of all N transmitting positions on a given section of the earth's surface.

3. The radiation pattern of the first receiving antenna is directed toward a given portion of the earth’s surface, and the beam patterns of the second weakly directed receiving antenna are oriented in the direction of N transmitting positions. 4. On board the receiving position using the antenna, oriented in the direction of a given plot of the earth's surface, N orthogonal SI _OTP signals are received. _-.- S _NOTP reflected from the observed portion of the earth's surface.

5. On board the receiving position, with the aid of an antenna oriented towards the transmitting positions, N direct orthogonal signals of direct propagation Sшр S _NП p are received, directly coming from N transmitting positions.

6. From the propagation signals S ι _PR • • •• S _{N P} p extract information about the state of each transmitter and its carrier, as well as the state of the propagation medium.

7. On board the receiving position for each pair of N direct and reflected signals corresponding to each other, N radar holograms are recorded corresponding to N different angles of irradiation of the observed portion of the earth's surface by each of the transmitter carriers.

8. On board the receiving position, N different angles of radar images (P LI) of the observed area of the earth’s surface are simultaneously synthesized. 9. Perform a joint analysis of a set of N different radar images.

This method has low efficiency of receiving radio images of the area, since operations 7 (recording holograms), 8 (synthesis of radio images) and 9 (analysis of radio images) require considerable time. At the current level of development of on-board computers using the signals of the GLONASS and GPS space navigation systems, the delay in receiving radio images reaches tens of minutes, and the entire processing device is very complex and has large dimensions, weight and power consumption. For this reason, the use of the method in question for the operational control of land from aboard small-sized unmanned aerial vehicles (UAVs) is difficult due to the large size and power consumption of the device that implements this method, and is inefficient due to the impossibility of observing the Earth in real time.

(iii) Disclosure of the invention

The technical result of the invention is to increase the efficiency of obtaining radio images of the underlying surface of the Earth and simplify the device that implements the method.

The essence of the method differs from the prototype in the list of operations at the receiving position and consists in the following:

1. From the board of N transmitting positions, transmitters (Rx) emit N independent navigation orthogonal probing signals Si .... S _N. 2. Oriented radiation patterns (NAM) of all N transmitting positions on a given plot of the earth's surface.

H. In a weakly directed antenna of each receiving position, one or more beams of the radiation pattern are formed and directed towards the transmitting positions.

4. In the antenna system of the receiving positions, M independent non-overlapping rays of the radiation pattern are formed and directed towards the observed portion of the earth's surface. 5. On board the receiving position with the help of beams oriented to the transmitting positions, receive N orthogonal sounding signals of direct propagation of Siпр .... S _NПР directly from N transmitting positions.

6. From the orthogonal sounding direct propagation signals Sipr .... S _Np p, information is provided on the status of each transmitter and its carrier, as well as on the propagation medium.

7. Navigation orthogonal sounding signals N of the transmitting positions Si neg .... reflected from the land surface sections are received .... S _{N OTP} are received at the receiving position by M independent receiving beams to M independent receivers (one for each beam).

8. In each receiver, the arrival time of the reflected orthogonal probe signals Si _OTP - - - _{N N OTR} FROM the sequence of m elementary sections of the earth's surface, “covered” with the corresponding receiving beam, is measured.

9. At the output of each receiver, a sequence of values of the power of the reflected signals S _{0TpI-N of} all N transmitting positions for each m-th elementary section is formed, and the sums These capacities are adjusted taking into account information on the state of each transmitter, its carrier, and distribution medium.

11. Form the envelope of the radio brightness of elementary sections of the earth's surface. To do this, the results of summing the power of the received reflected signals are arranged on the time axis according to the time of arrival of the reflected signals: from the earliest to the latest.

12. The envelope of the radio brightness is fed to the time-sweep system of the visualization device, an analysis of the results of radar observation of a plot of the earth's surface is carried out, highlighting the brightest point and determining the coordinates of the target (object) by combining the radio image with a digital map of the area.

A device for implementing the method comprises a transmitting position, including transmitters of orthogonal sounding signals, and a receiving position, located on board the aircraft, containing a weakly directional antenna and an antenna system that forms M independent non-overlapping beams. The directional patterns of a weakly directed antenna and antenna system are oriented towards the transmitters of the transmitting position and the earth's surface, respectively. The antenna system is connected respectively to the receivers of the reflected navigation signals, the outputs connected to the formers of the sequence of power values of the indicated signals, the outputs connected to the formers of the complete radio images, the outputs connected to the first input of the visualization of the current radio images, with the second, third and fourth inputs of which the onboard output is connected digital map storage devices, airborne sensor the flight altitude, pitch and roll of the BJIA, and the navigation equipment of the consumer, to the input of which a weakly directional antenna is connected, the outputs of the visualization device of the current radio images are connected to the input of the radio communication device.

(iv) Examples of implementation of the invention

A method of obtaining a radar image of the earth's surface using a multi-position radar system (PJIC) based on signals from satellite navigation systems GL O-HACC, GPS, GALILEO is illustrated by the drawings.

FIG. 1 is a diagram of a device that implements a method for obtaining a radar image of the earth’s surface using a multi-position PJIC. FIG. 2 shows the location of the beam relative to the earth's surface and the receiving position

In FIG. 3 shows power diagrams of signals reflected from elementary sections of the earth’s surface

In FIG. 4 shows a radio image of a portion of the earth's surface

In FIG. 5 shows a diagram for determining the boundaries of the DN trail. The following notation is introduced in the drawings:

1 - transmitting positions in the form of navigation spacecraft (HKA) satellite navigation systems GLONASS, GPS, GALILEO, with transmitters emitting navigation orthogonal sounding signals Si, S ₂ ..S _N , where N is the number of simultaneously visible KA at a given point on the earth's surface ;

2 - board an airborne aircraft (VLA) - receiving position; 3, 4 - sections of the earth's surface irradiated by navigation orthogonal sounding signals Si ... S _N ;

5 - low directional antenna for receiving direct propagation signals (reference signals) Si _pp ... S _Npr directly from the HKA;

6, 7 - BJIA antenna system, for example, in the form of side-view antennas, for receiving Siot- • • S _NoTP signals reflected from reflection elements to the left and right of the fuselage; 8, 9 - non-overlapping beams of the directional antennas of side-view antennas 6 and 7, directed to both sides of the fuselage into sections 4 and 3, respectively;

10 - consumer navigation equipment (NAL) of the G JIO-HACC, GPS, GALILEO systems, determining the coordinates, speed and course of the BJIA;

1 1 - on-board sensor for flight altitude, pitch and roll BJIA;

12 - on-board storage device for digital terrain maps (CCM), over which the BJIA moves;

January ₁₃ 13 ₂ - receivers reflected navigation signals Si _Neg ... S _NoTp, connected to the side-looking antennas 6 and 7, respectively;

14 _L H ₂ - shaper sequence reflected from elementary participants m power values of signals earth surface (conditioners elementary rows radio images); 15 _b 15 ₂ - formers of complete radio images corresponding to both antennas of the side view; lбi, 16 ₂ - device for visualization of current radio images;

17 - radio communication means for the operational transmission of the current radio image to the receiving point; 18 - radio antenna;

19-sided timeline storage device.

The device includes transmitting positions 1 and receiving position 2, which is located on board an aircraft. Transmitting positions include transmitters of orthogonal sounding signals. As transmitting positions

use navigation satellites (HKA) I ₁ , I ₂ , I _N satellite navigation systems G JI OHACC, GPS, GALILEO, which move in orbits about 20 thousand kilometers above the Earth. The transmitters radiate probing signals toward the earth's surface in the form of broadband noise-like signals in the ranges fi = l, 5 GHz and f ₂ = l, 2 GHz. All visible HKAs are involved in the formation of radio images on board an airborne aircraft (BJIA) 2, the number of which for BJIA is 6-12 pieces simultaneously for each of the systems (GLONASS, GPS, GALILEO).

Both the manned and unmanned aerial vehicles (UAVs) (aircraft, helicopters, cruise missiles, balloons, etc.) can be used as the VLA carrier for the receiving equipment: The device operates as follows:

1. From the board of the transmitting positions (1), which use the HKA of GLONASS, GPS, GALILEO systems, the transmitters in the direction of the Earth emit N navigation orthogonal sounding signals Sj ... S _N in two frequency band f] and f ₂ , which irradiate sections of the earth’s surface 3 and 4.

2. The radiation patterns (BF) of the side-view antennas BJIA 6 and 7 are oriented towards the Earth's surface to the left and right of the fuselage BJIA 2 (figure 2 rear view), and the radiation pattern the directional antenna 5 is oriented in the direction of the upper hemisphere of space toward N visible HKAs. In this case, the antenna bottom 5 covers the upper hemisphere of the space (a - \ 70 ÷ 180 °), and the non-overlapping rays 8 and 9 of the antenna bottom 6 and 7 “cover” surface areas 3 and 4, respectively. For these rays, the reflected signals Si from _p ... S _NoTp (Fig. L, Fig. 2) are sent through the antennas 6 and 7 to the input of the reflected signal receivers 13 ₁ and 13 _2, respectively, where they are separated by the numbers of the irradiating satellites. 3. On board the receiving position 2 using the antenna 5, oriented to the upper hemisphere of space and connected to it NAL 10 receive N orthogonal sounding signals of direct propagation Si _p ... SN _{P FR from the} transmitting positions I r I _N.

4. Ephemeris information about all visible HKAs is extracted from the direct propagation signals in NAL 10, the on-board storage device of the time scale 19 is synchronized by the temporary signal HKA, and the current coordinates X, Y of the projection of BJIA on the Earth's surface, speed and course of BJIA are determined.

5. Using the sensor 11 determine the current height H BJIA, as well as the pitch angle and roll angle β, which affect the position of the rays 8 and 9 of the bottom side antennas 6 and 7 (figure 2). Using these parameters, the sizes of “covered” by the rays 8 and 9 of the earth's surface 3 and 4 are determined. The sizes of the sites 3 and 4 are equal if the width of the rays 8 and 9 is the same, and β = 0. 6. In the visualization device of the current radio images lbi and

16 _{2 the} coordinates of the middle of the digital terrain map (CCA) from the on-board storage device 12 agree with the coordinates of BJIA 2 X, Y coming from NAL 10, and the axes of the CCM axes coordinate with the BJIA course coming from sensor 11. 7. In the formers H ₁ and 14 ₂ form a sequence of values of the power of the signals reflected from elementary sections of the earth's surface. The essence of this operation is illustrated by the example of the right side-view antenna 9, the beam of which covers a plot of terrain 3 (Fig.Z). The minimum allowable length δ _{m of an} elementary segment of the earth’s surface m is determined by the duration of the elementary signal τo of the pseudo-random sequence forming the signals Si -S _N HKA: δ _m = τ ₀ s, where C is the speed of light.

The signals from the transmitters HKA S], S ₂ ..S _{N are} simultaneously reflected from an elementary section of the earth's surface m. At this power reflected from that portion of the signal comprise Si _otp ^m, Sg _Neg ^"1 .... S _NoTp ^m - C ₁₃ February receiver output these signals different separately removed and fed to shaper shaper H ₂ H ₂ capacity of these added together. and get the sum of powers for one elementary section m

N

> = i

For all elementary sections along the track of the radiation pattern I ₃ form a sequence of values of the total power (Fig. 3) as a function of the current length I _{3 of the} trail:

N

S∑ neg ^m (b) ⁼ ∑ Sj oτp Oz) j (2) which represents the elementary row of the radio image for time t _j . This line is written to the shaper

H ₂ . In the shaper 14i, a line of the left radio image (for a plot of terrain 4) is similarly formed and recorded as a function of the current length 14 _{4 of the} trail of the beam:

N

∑ s _{i from p} ^m (i ₄ ) (3) i = i

8. In shapers 15] and 15 ₂ form and record radio images R ₃ , R ₄ of terrain as a function of the total power of the reflected signals on the distance along the trace of the antenna pattern 1 _3> I ₄ and on time t (Fig. 4):

N N

Rз (t) = ∑ S _{i opt} ^m (l ₃ , t); R ₄ (O = ∑ S _{i oτp} ^m (l ₄ , t) (4) i = li = l

9. In the devices lbj, 16 ₂ perform the visualization of radio images and combine them with a digital map of the area from the on-board storage device CCM 12.

Alignment with the CCM is made at the points: at the X, Y coordinates of BJIA and the coordinates of the boundaries of the trail DN 9 on the land surface 3: L ₃ 'and L ₃ "(Fig. 5).

The coordinates of the boundaries of the trace are determined from the formulas:

L ₃ '= H tan γ ,;

where Yi and γ ₂ are the angles of inclination of the boundaries of the DN to the vertical, H is the flight height of the BJIA. In the presence of roll β, the coordinates of the boundaries of the MD are determined from the formulas

L ₃ ^ = H t ₈ (Y ₁ + β) \

U ' ^P = Щ% b + β) -

After combining the MSC and the received radio images, they are analyzed and the coordinates of the targets on the earth's surface are determined by their coordinates on the combined MSC

10. Using the radio communication means 17 and the radio communication antenna 18, the current radio images, if necessary, are transmitted to the receiving point.

11. Using the on-board storage device, the time scales 19 synchronize all radio imaging devices.

The proposed method and device that implements it, have the following advantages

1. The device that implements the method is much simpler than the prototype device, since it does not contain a device for recording holograms and synthesizing radio images. The weight of the proposed device and its power consumption are several times less.

2. The proposed method provides a higher efficiency of receiving radio images, characterized by a delay in their receipt per unit time. In the prototype, due to the need for synthesis, the delay reaches tens of minutes. 3. Let us evaluate the resolution along and across the path.

The resolution along the path is determined by the ratio

δх = (λ / D _prm ) * R, (5) where λ is the wavelength of radio waves;

D _pM - the length of the aperture of the antenna, which forms the width of the side beam; R is the distance to the target.

At λ = 0.2 m (f = 1.5 GTZ), D _approx ⁼ 2 m, R = 500 m, we have δх = 50 m.

With decreasing flight altitude, the resolution increases.

The resolution across the path is determined, as noted, by the duration of the elementary signal of the pseudo-random M-sequence forming the navigation signal: δj = τо с. For the Glonass system, τ _o = O, 2 μs. For GPS, τ _o = O, l μs. Accordingly, δ] _GLON = 60 m, δi _G ps - 30 m.

These characteristics are not worse than the prototype. The method and device allows you to get images of targets disguised by technology "stealth". This is due to irradiation of targets with satellite signals from almost different sides in the multi-position radar mode.

The method and device provide radar immunity to passive interference such as corner reflectors, which is only effective in monolocation.

6 The method and apparatus allow a significant increase in the signal-to-noise ratio when receiving satellite signals reflected from the ground. When using NAL, simultaneously receiving signals from GLONASS GPS, GALILEO systems in two frequency ranges fi = 1.5 GHz and f ₂ = 1.2 GHz and with an average number of visible HKAs of each system of 10 pieces, we obtain noise / noise up to 60 (10 ^χ W ^χ 2). The proposed method is advisable to use on board small-sized aircraft such as micro-aircraft, unmanned aerial vehicles, airships, balloons.

Claims

Claim.

1. A method of remote sensing of the Earth using multi-position radar systems, which consists in the fact that the observed portion of the earth's surface is irradiated with orthogonal sounding signals from N transmitters at the same time, receive reflected signals and direct propagation signals of each of the N transmitters, from which information about the status of each transmitter is extracted , its carrier and the medium of distribution, characterized in that in the antenna systems of each receiving position form M non-overlapping independent of the rays of the radiation pattern in the direction of the earth’s surface, the signals reflected from the earth’s surface in each independent beam are received on a separate receiver, in each receiver the signals of all transmitters reflected from the elementary part of the earth’s surface are separated, summed by power and form radio images of the earth’s surface in the form of a distribution radio brightness in space along and across the line of movement of the carrier of the radar system, combine the radio image with a digital map of the area and determine are coordinates of the points having high brightness.

2. A device for remote sensing of the Earth using multi-position radar systems, comprising a transmitting position including transmitters of orthogonal sounding signals, and a receiving position located on board an airborne aircraft (BJIA) containing a weakly directed antenna and an antenna system that forms M independent non-overlapping beams radiation patterns

3. The directional patterns of a weakly directed antenna and antenna system are oriented towards transmitters of the transmitting position and the earth’s surface, respectively, the antenna system is connected respectively to the receivers of the reflected navigation signals, the outputs are connected to the formers of the sequence of power values of these signals, the outputs are connected to the formers of complete radio images, the outputs are connected to the first input visualization devices for current radio images, with second, third and fourth The gated inputs of which are connected to the output of the on-board device for storing digital terrain maps, the on-board sensor of flight altitude, pitch and roll of the BJIA, and the navigation equipment of the consumer, to the input of which a weakly directional antenna is connected, the outputs of the visualization device for the current radio images are connected to the input of the radio communication device.