CN1776451A - Radio emitting source positioning method and system - Google Patents

Abstract

The method includes steps: (1) using antenna in directivity receives scattered signal of aeroplane on emitter; (2) recording frequency spectrum of scattered signal and corresponding time; and based on frequency spectrum and time, obtaining Doppler shift; (3) based on Doppler shift and flying mode of the aeroplane, calculating position of emitter so as to realize positioning emitter. The invention solves issue of finding source of interference on communication frequency of civil aviation. Features are: large covering area, without need of modifying aeroplane and affecting normal flight of civil aviation, positioning implemented by single station, high flexibility and saving maintenance cost.

Description

Radio emitting source positioning method and system

Technical field

The present invention relates to the radio monitoring technology, concretely, relate to a kind of radio emitting source positioning method and system of aircraft.

Background technology

Since in April, 2004, the civil aviation frequency range is subjected to the interference of the artificial malice radio signal on ground often, and serious threat is to the flight safety of airline carriers of passengers.Artificial malicious interference to search difficulty very big, mainly adopt method at the location of this interference source at present in the surface deployment monitoring station, the direction finding result by a plurality of monitoring stations direction-finding system realizes cross bearing, determines the position of interference source.

Yet in actual applications, because the antenna installation height of monitoring and direction finding system is limited, be subjected to the influence of earth curvature, surface buildings and trees vegetation etc., the monitoring coverage that causes monitoring and direction finding system is (the monitoring covering radius is generally less than 30 square kilometres) in the very little zone; And if the aircarrier aircraft of high-altitude flight is subjected to co-channel interference, the regional extent that interference source may exist is (border circular areas that is about 200 kilometers of radiuses) greatly.If therefore utilize existing monitoring and direction finding system location interference source, just must take large tracts of land to lay the method for monitoring and direction-finding station, the problem of bringing is that investment is huge, the 2nd, system's operation expense is very high.If installation monitoring aboard, direction-finding equipment are monitored in the air, because the aircraft improvement cost is very high, the same huge problem of investing that exists; Moreover, because the appearance of disturbing is at random, must repeatedly repeat aerial mission, the operation expense of total system is also very high, and might influence normal airflight order.

Summary of the invention

The object of the present invention is to provide a kind of radio emitting source positioning method and system, especially at described emissive source the situation of radio interference source, by catch the signal that undesired signal falls earthward after the aircarrier aircraft scattering, the information calculations such as Doppler shift of utilizing airplane motion to produce are determined the position of interference source, existing terrestrial radio EVAC (Evacuation Network Computer Model) is difficult to directly to receive the ground undesired signal, coverage is little, the problem that expense is high thereby solve.

To achieve these goals, technical scheme of the present invention is:

A kind of radio emitting source positioning method, it comprises the steps:

A. the direction of passage antenna receives the scattered signal of aircraft to emissive source;

B. write down the frequency spectrum and the time corresponding thereof of scattered signal, and, obtain Doppler shift according to described frequency spectrum and time information;

C. according to the state of flight of described Doppler shift and aircraft, calculate the position of emissive source, thereby realize location described interference source.

Wherein, step a also comprises: according to the long-pending horizontal direction angle and the elevation angle of selecting monitoring point, ground, directive antenna of aircraft scattering cross-section.

Also comprise before the step b: the scattered signal that receives is carried out filtering and processing and amplifying;

Described Doppler shift comprises: the Doppler shift the when Doppler shift when the emissive source signal arrives aircraft scatters to ground again with the emissive source signal that arrives aircraft.

The state of flight of aircraft comprises among the step c: flying height, speed and position.

Doppler shift when the signal that described state of flight is launched according to aircraft arrives ground calculates.

A kind of radio emitting source positioning system, it comprises:

Directive antenna, receiver and data processing equipment;

Described directive antenna is used to receive the scattered signal of aircraft to emissive source;

Described receiver is used to write down the frequency spectrum and the time corresponding thereof of described scattered signal, and described receiver has data output interface, is used for output data;

Described data processing equipment, be used for the frequency spectrum and the time data of receiver output are carried out digital processing, calculate the Doppler shift of undesired signal, and the position of calculating emissive source according to the state of flight of described Doppler shift and aircraft, thereby the location of finishing emissive source.

Described system also comprises: wave filter and low noise amplifier, the described scattered signal that described directive antenna receives is input to described receiver after filter filtering and low noise amplifier amplification.

The gain of described directive antenna is greater than 12dBi.

The frequency resolution of described receiver is better than 1Hz.

Beneficial effect of the present invention is, according to radio emitting source positioning method of the present invention and system, efficiently solve searching problem of civil aviaton's communication frequency interference source, interference source of the present invention locatees that not only coverage is big, only needs a monitoring station can cover all viewing areas of aircraft; And do not need aircraft is changed, can not influence civil aviaton's normal flight yet, saved investment; And adopt single station can realize the location, mobility strong has been saved maintenance cost again.

Description of drawings

Fig. 1 is the structured flowchart of radio interference source positioning system of the present invention;

Fig. 2 is the synoptic diagram of object scattering;

Fig. 3 calculates the coordinate system that the aircraft position is set up in the embodiment of the invention;

Fig. 4 a and Fig. 4 b are respectively the waterfall figure of the scattered signal that actual measurement of the present invention obtains.

Embodiment

Understanding the present invention for more deep is elaborated to specific embodiments of the invention below.

Be that example describes in an embodiment of the present invention with the radio interference source, but emissive source of the present invention is not limited to interference source, also comprises any emissive source that can monitor by method and apparatus of the present invention.

The present invention is by receiving the scattered signal of aircraft to interference source, extract its Doppler shift information from the scattered signal that receives, utilizing Doppler shift information that interference source is positioned.Aircraft of the present invention not only comprises the aircraft on the traditional definition, also comprises other airborne aircraft.

Fig. 1 is the structured flowchart of radio interference source positioning system of the present invention.As shown in Figure 1, the ground of the present invention radio interference source positioning system of setting up comprises:

Antenna is used to receive the scattered signal of aircraft to interference source, owing to will realize the distance reception of signal, so present embodiment adopts is high gain directional antenna, and for example log-periodic antenna or antenna array require gain greater than 12dBi;

Wave filter, be used for the scattered signal that antenna receives is carried out filtering, garbage signal outside the filtering passband, what present embodiment adopted is the dedicated band pass of the special-purpose frequency range of civil aviaton (108MHz to 137MHz), requires to have lower insertion loss and good form factor and rejection ratio;

Low noise amplifier is used to amplify described scattered signal, and what present embodiment adopted is the special-purpose amplifier of civil aviaton's frequency range (108MHz to 137MHz), requires absolute low noise and certain enlargement factor.

The high-sensitivity digital receiver, requirement has very high receiving sensitivity in the special-purpose frequency range of civil aviaton, can show the also frequency spectrum of non-volatile recording signal with high frequency resolution (being better than 1Hz at least), in record, each frequency spectrum is constantly stamped time mark, digital channel is provided simultaneously, to link to each other, be convenient to post analysis and processing with devices such as computing machines.

Data processing equipment is a high-performance computer in the present embodiment, is used to finish the digital processing of digital receiver output signal, comprises the Doppler shift and the position of interference source that calculate input signal, and good man computer interface is provided.

By described system, just can realize the location of radio interference source.Radio interference source localization method of the present invention comprises:

1) selects monitoring point, ground and definite monitoring range

After receiving the interference complaint of department of civil aviaton, the approximate range that interference source is determined in the position appears in the interference according to civil aviaton's Section report, long-pending according to the scattering cross-section of aircraft then, distribute and surface state in conjunction with the course line, select the level orientation angle and the elevation angle of monitoring point, ground and directive antenna.

The foundation of selecting is: the scattered signal that guarantees can capture with big as far as possible probability interference source in the overlay area on the aerial angle of selected place and correspondence, promptly put corresponding incident angle, and the scattering cross-section long-pending (RCS) under the corresponding scattering angle is bigger for great majority in the overlay area.For example, airline carriers of passengers is interfered in the 120MHz frequency, we can call the long-pending data of RCS at 120MHz frequency place, at each scattering angle (being a stepping for example) every 5 degree, the RCS of statistics all incident angle correspondences under this frequency, this scattering angle checks the probability of these RCS greater than certain predetermined threshold.Can exhaustive all scattering angles, find out that of probability maximum, put angle so obtain monitor spots, best ground with respect to aircraft; In conjunction with the position that aircarrier aircraft is interfered, just can obtain the position at ground monitoring station by above-mentioned best angle.

The aircraft scattering cross-section is long-pending can be obtained by the Computer Simulation computed in software in advance.Introduce the long-pending calculating of aircraft scattering cross-section below.

When object during by electromagnetic wave irradiation, energy is with the one way or another scattering.The space distribution of energy depends on shape, size and structure and the incident wave frequency and the characteristic of object.This distribution of energy is called scattering, and object itself is commonly referred to target and scatterer.As shown in Figure 2, when the scattering direction is not when pointing to radiation source, be called two station scatterings, the present invention mainly considers the situation of two station scatterings.

The definition of rebecca scattering cross-section is based on the notion of target isotropic scatterning under the plane wave illumination, and for a kind of like this ripple, its projectile energy density is $W_i=\frac{1}{2}{E}_i{H}_i=\frac{1}{2}{Y}_0{\left|E_i\right|}^2;$ E in the formula _iAnd H _iBe respectively the electric field intensity and the magnetic field intensity of incident electromagnetic wave, Y ₀It is the admittance of free space.Therefore, the general power of target intercepting is $P=\mathrm{\σ}{W}_i=\frac{1}{2}\mathrm{\σ}{Y}_0{\left|E_i\right|}^2.$ σ represents the scattering cross-section of target in the formula.

If these power isotropically radiate now, then be the distant place of R at distance objective, its scattering power density is:

$W_s=\frac{P}{4\mathrm{\π}{R}^2}=\frac{\mathrm{\σ}{Y}_0{\left|E_i\right|}^2}{8\mathrm{\π}{R}^2}---\left(I\right)$

Yet scattering power density again can be by scattering electric field E _sExpression:

$W_s=\frac{1}{2}{Y}_0{\left|E_s\right|}^2---\left(\mathrm{II}\right)$

Make formula (I) and (II) formula equate, can obtain $\mathrm{\σ}=4\mathrm{\π}{R}^2\frac{{\left|E_s\right|}^2}{{\left|E_i\right|}^2}.$

Because incident wave is a plane wave, and because hypothetical target is equivalent to point scatterer, so distance R should be tending towards infinity.Thereby the RCS formula can more strictly be written as $\mathrm{\σ}=\underset{R\→\∞}{\lim }4\mathrm{\π}{R}^2\frac{{\left|E_s\right|}^2}{{\left|E_i\right|}^2}.$ The basic definition of RCS that Here it is.

We adopt the Computer Simulation software (as finite element emulation software) of existing calculating scattering cross-section, select typical aircarrier aircraft type, in the special-purpose frequency range of civil aviaton, calculate airline carriers of passengers in different incident, RCS long-pending (RCS) under the scattering angle:

1. set up model aircraft accurately, come the characteristic of emulation aircarrier aircraft scattering electromagnetic field.For finite element algorithm, the radiation border need be set, promptly limit the area of space of finite element iterative computation, the distance of this border and the model aircraft that we set up must be greater than 1/4 wavelength (wavelength can be converted by selected frequency), and the radiation border is preferably similar to the shape of model;

2. set into the direction of ejected wave (undesired signal), and set into the character of ejected wave, what we selected is the spherical wave of vertical polarization;

3. set calculative characteristic frequency point;

4. set iterative step and corresponding end condition (error range);

5. begin the iterative computation process, try to achieve the surface current of model aircraft;

6. after iterative computation finishes, scattering wave line of propagation scope is set and begins the calculating of RCS, can one-time calculation go out the RCS of all scattering directions under the incident wave direction situation that is provided with previously.

7. saving result.

8. change parameters such as frequency, incident wave direction, repeat aforementioned calculation.

By said process, each scattering direction RCS that we can obtain under the airline carriers of passengers, different incidence angles degree, different frequency of different model is long-pending.

2) Doppler shift obtains

Behind the selected ground monitoring point, set up the ground monitoring station in the relevant position.At first all receptions, record analysis equipment are carried out time calibration, guarantee temporal complete synchronism by precise time reference source (for example GPS).When undesired signal occurring, receive the scattered signal that undesired signal falls earthward by the high-gain directive antenna after the aircraft scattering, through the special filter filtering of positioning system of the present invention and after special-purpose amplifier amplifies, the frequency spectrum of scattered signal between the interference apparition writes down corresponding precise time simultaneously by described high-sensitivity digital receiver observation and record.The record result is shown in Fig. 4 a and Fig. 4 b.

Fig. 4 a and Fig. 4 b are the time dependent waterfall figure of aircraft scattered signal that twice test records, and transverse axis is a frequency, and the longitudinal axis is time (through the gps time calibration).Wherein, the curve that has marked point is only useful data, and it is a measured data, is the Doppler effect that produces owing to the aircraft high-speed motion, scatters to the time dependent track of frequency of the signal at ground monitoring station behind the ground undesired signal arrival aircraft again.And the curve that does not mark with point is irrelevant received signal in the present invention.By reading the time dependent track of last figure medium frequency, can obtain the frequency of different time points correspondence, this frequency is that the Doppler effect of aircraft high-speed motion causes.

3) interference source location

Ground, location interference source needs two steps altogether, and the first step is to determine aircraft position at any time, and second step was the position of determining the ground interference source.Set forth respectively below.

(1) determines aircraft position at any time.

In order to locate the ground interference source, at first need to determine the state of flight of aircraft, comprise flying height, speed and position.If can obtain aircraft state of flight (providing) at any time, then do not need to carry out following calculating about the aircraft position from other approach as department of civil aviaton; Otherwise we will position aircraft by aircraft self Doppler shift that brings that transmits, about being calculated as follows of aircraft position.

By following analysis as can be seen,, during known flying height, carry out 4 samplings, then can utilize Doppler shift to calculate flying speed and position by aircraft self is transmitted for the aircraft of linear uniform motion.

Set up coordinate system shown in Figure 3.If initial point is the position, monitoring station, the xy plane is ground; Suppose the aircraft unaccelerated flight, the course line is parallel to the x axle, and flying height is a h[rice], the bias of course line in ground projection and monitoring station is y _p[rice], the i coordinate of aircraft constantly are (x _i[rice], y _p[rice]), the interference source coordinate is (x _g[rice], y _g[rice]); Angle [alpha] among the figure _iBe the angle of i moment aircraft and interference source line and heading, β _iIt is the angle of i moment aircraft and monitoring station line and heading.

Suppose that aircraft transmission frequency in flight course is f ₀The signal of [hertz].Owing to have direct wave, can receive these signals (f at an easy rate from the monitoring station _0geti[hertz]):

f _0geti＝f ₀+Δf _0i (1)

Δ f wherein _0iIt is i frequency f constantly ₀The Doppler shift of signal when arriving ground.

$\mathrm{\Δ}{f}_{0i}=\frac{v}{c}\·\cos {\mathrm{\β}}_i\·f_0=\frac{v}{c}\·\frac{-x_i}{\sqrt{x_i^2+h^2+y_p^2}}\·f_0---\left(2\right)$

V[meter per second wherein] be flying speed, x _i[rice] is the i x coordinate of aircraft position constantly, and c is a propagation velocity of electromagnetic wave (3 * 10 ⁸Meter per second).(2) substitution (1) formula is obtained:

$\frac{v}{c}\·\frac{-x_i}{\sqrt{x_i^2+h^2+y_p^2}}\·f_0=f_{0\mathrm{geti}}-f_0---\left(3\right)$

In order to reduce the number of unknown number, with x _i=x ₀+ v * t _0iSubstitution (3).X wherein ₀[rice] is the x coordinate of 0 moment aircraft, t _0i[second] is to f ₀I sampling instant of frequency.Because f ₀Exact value the unknown is removed unknown number f by method of elimination ₀, obtain following equation with three unknowns group:

$\frac{\frac{c}{v}+\frac{-(x_0+v\·t_{01})}{\sqrt{{(x_0+v\·t_{01})}^2+h^2+{y_p}^2}}}{\frac{c}{v}+\frac{-(x_0+v\·t_{0i})}{\sqrt{{(x_0+v\·t_{0i})}^2+h^2+{y_p}^2}}}=\frac{f_{0\mathrm{get}1}}{f_{0\mathrm{geti}}},$ I=2 wherein, 3,4 (4)

Solving equation group (4) can get x ₀, y _p, v.According to x ₀And v, can be in the hope of the position of any time aircraft.

(2) determine the position of ground interference source

By the calculating of front, we have obtained the position and the flying speed of any time aircraft.Utilize above-mentioned information and to interfering frequency f _gThe position that the information of three samplings just can be calculated the ground interference source.

Doppler shift when 1. the j moment, undesired signal arrived aircraft is:

$\mathrm{\Δ}{f}_{\mathrm{gj}}=\frac{v}{c}\·\cos {\mathrm{\α}}_i\·f_g=\frac{v}{c}\·\frac{x_g-x_j}{\sqrt{{(x_j-x_g)}^2+{(y_g-y_p)}^2+h^2}}\·f_g---\left(5\right)$

Wherein, f _g[hertz] is the frequency of undesired signal, (x _g[rice], y _g[rice]) be the interference source coordinate, (x _j[rice], y _p[rice]) be the j coordinate of aircraft constantly, the meaning of other parameters is the same.

2. j (t constantly _j) when the undesired signal that arrives aircraft scattered to ground again, the Doppler shift that causes was:

$=\frac{v}{c}\·\frac{-x_j}{\sqrt{x_j^2+h^2+y_p^2}}\·[f_g+\frac{v}{c}\·\frac{x_g-x_j}{\sqrt{{(x_j-x_g)}^2+{(y_g-y_p)}^2+h^2}}\·f_g]$

$=f_g[\frac{v}{c}\·\frac{-x_j}{\sqrt{x_j^2+h^2+y_p^2}}+{\left(\frac{v}{c}\right)}^2\·\frac{x_g-x_j}{\sqrt{{(x_j-x_g)}^2+{(y_g-y_p)}^2+h^2}}]$

Because (v/c) much smaller than 1, omit in the following formula and have (v/c) in the square bracket ²Second, obtain:

3. set up system of equations and find the solution position of interference source:

For frequency is f _gUndesired signal, j constantly the receive frequency when arriving ground after the aircraft scattering be:

f _Geti=f _g+ Δ f _Gj+ Δ f _{The g j that looses}

F wherein _Getj[hertz] is j (t constantly _j) receive the frequency of interference source scattered signal on ground.

With (5), (6) formula substitution, obtain:

$f_g\·[1+\frac{v}{c}\·\frac{x_g-x_j}{\sqrt{{(x_j-x_g)}^2+{(y_g-y_p)}^2+h^2}}+\frac{v}{c}\·\frac{-x_j}{\sqrt{x_j^2+h^2+y_p^2}}]=f_{\mathrm{getj}}---\left(7\right)$

J=1 wherein, 2,3.

Has only x in the above-mentioned system of equations _g, y _g, f _gThree unknown numbers, all the other parameters are all known.Find the solution this equation with three unknowns group, can obtain the position (x of ground interference source _g, y _g).

Because the symmetry of linear uniform motion, the position of interference source of trying to achieve must have two groups, is symmetrically distributed in the both sides, course line respectively.By the reality investigation, from two positions, find the position in actual interference source.

In May, 2005, the correlative study personnel of Country Radio Monitoring Center successfully repeatedly catch the aircarrier aircraft scattered signal in the Bazhou, Hebei, proved the feasibility of utilizing scattered signal that the ground interference source is positioned.

2005 8, the research group that the technician of Country Radio Monitoring Center forms is near Bazhou, the Hebei civil aviaton line of flight, utilize the aircraft scattered signal that civil aviaton's frequency range radio interference source is carried out on-the-spot feasibility assignment test checking, it is meteorological with the aircraft scattered signal of broadcasting with the ground communication frequency to catch the airport continuously, and, successfully the meteorology that is positioned at the Capital Airport is located with broadcasting signal by the data of gathering are analyzed and handled.

Positioning result to interference source shows, positioning error is less than 20km (maximum error 18km), and this shows and utilizes the aircarrier aircraft scattered signal that the method that the ground interference source positions is achieved success.

Interference source localization method of the present invention and system are not limited to the interference source to aircraft described in the embodiment and position, and disturb on the ground that is equally applicable in other aircraft visual ranges.

Because have no occluder exists between the aircarrier aircraft of monitoring station and high-altitude flight, the signal cover of its monitoring aircraft scattering is far longer than existing common ground monitoring direction finding site, its maximum covering radius can reach about 150 kilometers, has thoroughly solved the little problem of existing ground monitoring direction finding site coverage.

With respect to prior art, the present invention has following advantage:

1, coverage is big.

Do not block because the path that the path of interference source arrival aircraft and aircraft arrive the monitoring station does not exist, only need a monitoring station can cover all viewing areas of aircraft in theory.

2, do not need aircraft is changed, do not influence civil aviaton's normal flight, saved investment.

This monitoring system only needs to receive the signal that this metallic object of aircarrier aircraft scatters to ground, thereby does not need aircarrier aircraft is made any change, and also can not influence the normal flight of civil aviaton, and the construction cost of system is lower.

3, adopt single station can realize the location, mobility strong is saved operation expense.

Native system only need can be realized the location work of interference source in monitoring station of ground configuration, has flexible, easy-to-mount advantage.Save the operation expense of system greatly in a plurality of monitoring stations with respect in the monitored area, extensively arranging.

Above embodiment only is used to illustrate the present invention, but not is used to limit the present invention.

Claims (12)

1. a wireless transmit source location method is characterized in that, comprises the steps:

A. the direction of passage antenna receives the scattered signal of aircraft to emissive source;

B. write down the frequency spectrum and the time corresponding thereof of scattered signal, and, obtain Doppler shift according to described frequency spectrum and time information;

C. according to the state of flight of described Doppler shift and aircraft, calculate the position of emissive source, thereby realize location described emissive source.

2. method according to claim 1 is characterized in that:

Step a also comprises: according to the long-pending horizontal direction angle and the elevation angle of selecting monitoring point, ground, directive antenna of aircraft scattering cross-section.

3. method according to claim 1 is characterized in that:

Also comprise before the step b: the scattered signal that directive antenna is received carries out filtering and processing and amplifying.

4. method according to claim 1 is characterized in that:

The state of flight of described aircraft comprises: flying height, speed and position.

5. method according to claim 1 is characterized in that: the Doppler shift the when signal that described state of flight is launched according to aircraft arrives ground calculates.

6. method according to claim 1 is characterized in that:

Described Doppler shift comprises: the Doppler shift the when Doppler shift when the emissive source signal arrives aircraft scatters to ground again with the emissive source signal that arrives aircraft.

7. wireless transmit source location system is characterized in that comprising:

Directive antenna is used to receive the scattered signal of aircraft to emissive source;

Receiver is used to write down the frequency spectrum and the time corresponding thereof of described scattered signal, and described receiver has data output interface, is used for data output;

Data processing equipment, be used for the frequency spectrum and the time data of receiver output are carried out digital processing, calculate the Doppler shift of emissive source signal, and the position of calculating emissive source according to the state of flight of described Doppler shift and aircraft, thereby the location of finishing emissive source.

8. system according to claim 7 is characterized in that also comprising: wave filter and low noise amplifier, the described scattered signal that described directive antenna receives is input to described receiver after filter filtering and low noise amplifier amplification.

9. system according to claim 7 is characterized in that:

The gain of described directive antenna is greater than 12dBi.

10. system according to claim 7 is characterized in that:

The frequency resolution of described receiver is better than 1Hz.

11. system according to claim 7 is characterized in that:

Described Doppler shift comprises: the Doppler shift the when Doppler shift when the emissive source signal arrives aircraft scatters to ground again with the emissive source signal that arrives aircraft.

12. system according to claim 7 is characterized in that:

The state of flight of described aircraft comprises: flying height, speed and position.

Images