Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/0257—Hybrid positioning
  • G01S5/0268—Hybrid positioning by deriving positions from different combinations of signals or of estimated positions in a single positioning system
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
  • G01S7/021—Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
  • G01R29/08—Measuring electromagnetic field characteristics
  • G01R29/0807—Measuring electromagnetic field characteristics characterised by the application
  • G01R29/0814—Field measurements related to measuring influence on or from apparatus, components or humans, e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/0249—Determining position using measurements made by a non-stationary device other than the device whose position is being determined
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/12—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Definitions

• the present invention relates to a method for locating an electromagnetic source.
• the invention also relates to a treatment device capable of implementing this method. It also relates to a system implementing this method.
• the invention can be applied in many situations. It can in particular be applied for the elaboration of a tactical situation that is to say for the location of emission of fixed or mobile radars, slow or fast, in terrestrial, maritime or airborne contexts starting from a network of Radar Detectors (a Radar Detector being hereinafter referred to in the document as ESM for Electronic Support Measure) fixed or mobile on land, sea, drone, aircraft or helicopter vehicles.
• ESM Electronic Support Measure
• the localization is based on iterative methods by gradient, by the maximum likelihood estimation, requiring calculations of step of the gradient often consuming resources in terms of computational power, or methods requiring to digitize the data. research space.
• An object of the invention is especially to estimate the location of the emission by a direct calculation and therefore not iterative.
• the subject of the invention is a method for locating an electromagnetic emission source from an ESM receiver network, said source emitting an emission beam scanning the space, said method comprising:
• said method comprises:
• ADOA measurement a step of measuring an arrival angle difference ( ⁇ ) of said emission beam on two receivers
• TDOA measurements a step of measuring the arrival time difference of said transmission beam on said two receivers
• said method comprises a step of measuring the time difference of passing said transmission beam on two receivers, called the DTPL measurement;
• TDOA measurements a step of measuring the arrival time difference of said transmission beam on said two receivers
• the calculation of said cylinder is for example carried out in two dimensions, corresponding to a given altitude, corresponding to the calculation of a circle, the position of said source being the intersection of said circle and said iso-TDOA hyperbola.
• ESM sensors are for example worn by an aircraft.
• Said network comprises for example a single ESM sensor, the measurements being made in two consecutive positions of said sensor.
• the step of calculating the position of said source at a given instant is for example followed by a Kalman filtering step and prediction of the positions of said moving target.
• the invention also relates to a processing device able to communicate with an ESM sensor network, said device being able to implement the method as described above.
• the invention also relates to a system for locating an electromagnetic emission source comprising at least one ESM sensor network and processing means implementing said method.
• FIG. 2 an illustration of the type of measurements used
• FIG. 3 an illustration of a measurement of the DTPL type, measure of time difference of transmission lobes
• FIG. 4 a representation of a scanning radar lobe intercepted by two ESM receivers
• FIG. 5 a representation of the positions of a target and of two ESM receivers in an orthogonal reference frame
• FIGS. 6a and 6b an example of a geometric locus used in the implementation of the invention, a cylinder in this example;
• FIG. 7 an example of a change of reference allowing the calculation of a second locus used in the method according to the invention.
• FIG. 1a shows a target 1 producing a transmission 10.
• the target 1 is a rotating radar.
• Two ESMs are embedded on two mobile carriers 1 1, 12, each carrier being equipped with an ESM.
• FIG. 1b illustrates the same configuration but with two fixed ESMs 13, 14.
• the invention deals with the location of a fixed transmission by two fixed or mobile ESM stations. However, it can be applied to a single ESM station in motion.
• the invention can also be applied to a mobile emission, slow or fast, insofar as the estimation being performed on a lobe passage, the successive positions can then be filtered by many conventional methods including a Kalman filter. We then obtain a sequence of positions integrated by the filtering with a reconstitution of the speed of the target.
• Figure 2 illustrates the two types of measurements used. Two types of measures are considered: - The ADOA (Angular Difference Of Arrival) type measurement measuring the arrival angle difference ⁇ of the radar emission on two remote ESM receivers 21, 22;
• ADOA Angular Difference Of Arrival
• the two ESMs 21, 22 can be called ESM1 and ESM2 respectively.
• the measurement of the ADOA type can in particular be carried out by the following different methods:
• the arrival frequency Doppler frequency measurement known as FDOA Frequency Difference Of Arrival
• the DOA measurement can in particular be carried out by measuring the arrival time difference of the radar pulses on two remote ESM receivers 21, 22 corresponding to two carrier aircraft.
• the method applies to particular type of radar emissions.
• the DTPL measurement applies to constant-scan radars.
• the measurement of the single-receiver ESM FDOA applies to coherent waveforms.
• the measurement of DTPL can be obtained by considering the difference of the TPL (lobe passing time) of the same lobe on the two ESMs;
• the TDOA measurement results from the difference in radar reset arrival times on the two remote ESMs.
• Figure 3 illustrates the measurement of DTPL.
• This Lobes Passage Time Difference measurement is the difference in transit time T of a radar that sweeps at speed ⁇ on two fixed stations.
• the example of Figure 3 is given without loss of generalities and the same equations apply to the first order even for fast mobiles. Assume the following situation:
• a radar 1 emits by scanning the space at a rotation speed ⁇ assumed fixed and known;
• the passage of the main lobe 31 is observed on two ESM stations 21, 22.
• the time of passage of the main lobe is t 1 on the first, ESM1, and t 2 on the second, ESM2;
• n 12 is a supposed Gaussian noise of standard deviation of 1 to 5 ms. The date of passage of lobe can be obtained with this precision by integration on the successive lobes.
• the measurement of the difference in arrival time between the two remote observers 21, 22 is also considered.
• the measurement techniques used in radar and EW have notably been described in the article by Quazi, AH. in active and passive Systems for target localization "IEEE ASSP-29, No. 3, June 1981, pages 527-533.
• the technique used consisting in the search for the peak of the intercorrelation function is also presented in the article by Piersol, AG "Time delay Estimation Using Phase Data", IEEE ASSP-29, No. 3, June 1981, pages 471 -477.
• There are several other competing techniques including a technique using the Fourier transform phase of the intercorrelation function.
• the TDOA Time Difference Of Arrival
• the TDOA corresponds to the time difference during the course of r 1 and r 2 by the radar waves.
• n 12 in the equation (1) of the DTPL because n 12 is of the order of 1 ms and the distance between the stations 21, 22 is of the order of 3 km.
• the localization is obtained by finding the values of the position of the emission which simultaneously satisfy these two equations.
• the present invention relates neither to the deinterlacing function, nor to the function of characterizing the lobes, nor to the function of association of the lobes in the monoplate-form, nor to the function of identifying the emission. These operations are known and assumed to be performed elsewhere.
• the elemental localization provided on a lobe passage may be integrated by any tracking of the transmission lobe sequences over time.
• FIG. 4 represents the lobe 41 of the scanning radar 1 intercepted by the two ESMs, ESM1 and ESM2.
• the location method performs the following steps: - For each ESM i. o For each intercepted lobe k, compute a quadruplet of measures ⁇ TOA k , TPL k , LL k , Lv k ). summarizing the geometric parameters of the lobe 41, this lobe being also characterized by a summary of the characteristics of the FO (PRI, Frequencies, Dl, intra-pulse codes ).
• FIG. 5 shows the target 1 and the two ESM receivers 21, 22 in a mark O, x, y, z at the time of an i th extent, i ranging between 1 and N.
• two observers 21, 22 perform N TDOA measurements (difference in arrival time of the same signal between the two remote sensors 21, 22) and DTPL (difference in lobe passing time) on the fixed target 1.
• the measurement of TDOA and the measurement of DTPL are recorded between the first receiver 21 and the second receiver 22.
• R 1, i and R 2 respectively, denote the respective distances of the first and second receivers to the target.
• the coordinates of the target, the first receiver and the second receiver to the ith measurement are respectively:
• the points giving the same measurement of DTPL for given receiver positions are located on a cylinder 61 called the iso-DTPL circle shown in Figure 6a.
• This cylinder contains the positions ⁇ - ⁇ , P 2 of the receivers 21, 22 and the position Pe of the target 1.
• the points giving the same measurement of TDOA for given receptor positions are located on a hyperboloid called iso-TDOA hyperboloid, which is obtained by the calculations presented hereinafter from the representation of FIG. 7.
• the position Pe of the target 1 and the positions P 1 , P 2 of the receivers 21, 22 are calculated in a new orthogonal coordinate system ⁇ ', x', y ', z' where O 'is equal to Pi and the axis x' passes through P 1 and P 2 .
• the position Pe is indicated by the coordinates (x ' e , y' e , z ' e ).
• R 1, R 2 the respective distances of the first and second receiver 21, 22 to the target, and the distance 12 is noted between these two receptors.
• the method according to the invention forms, from the measurements, a polynomial equation of degree 4 which is then solved by using methods of explicit resolution of this type of equation.
• Several known methods of resolution can be used, among them we can mention the resolution of a degree equation of 4 by the method of Ferrari or the resolution of an equation of degree 4 by the method of Lagrange.
• the resolution algorithm produced is therefore an explicit algorithm and does not use conventional gradient resolutions, for example MLE (Maximum Likehood Estimation) type algorithms, also called EMV (Maximum Likelihood Estimation).
• MLE Maximum Likehood Estimation
• EMV Maximum Likelihood Estimation
• an execution time can be calculated according to the number of input data
• the method according to the invention is therefore suitable for real-time execution. Indeed, it uses a memory size and requires a calculation time both of which are predictable. It applies advantageously to many types of ESM measurements.
• the altitude error in Z, has no influence on the iso-DTPL cylinder. It may then be advantageous to eliminate the variable Z in the resolution by setting the value of the altitude to avoid artificial indeterminacy in the system of equations. Indeed, given that the altitude error has a weak influence, it may be better not to try to to estimate it to avoid this artificial indeterminacy. If one wishes to obtain a greater precision, after a calculation of localization estimating a first localization, one specifies the altitude with this point of localization using the numerical model of the ground at disposal. The process is then repeated from this altitude using the same explicit resolution according to the invention.
• the instantaneous locations obtained can be processed by Kalman filtering to estimate the evolution of the target. From a position calculation at a given moment, it is thus possible to predict the positions of the target over time.
• the invention has been described for measurements of the DTPL type, measuring differences in transit time of the transmission beam of the source, and for TDOA type measurements, giving differences in arrival time of the beam of transmission, the transmission beam being intercepted on two remote fixed or mobile ESMs.
• a system implementing the method according to the invention comprises at least one network of ESM sensors performing the various measurements and processing means for determining the location of an electromagnetic emission source from these measurements.
• the processing means are for example integrated in a device able to communicate with the ESM sensors. From the signals received by the sensors, the processing means determine the differences in arrival angles and arrival directions. For this purpose, the signals received by the sensors are recorded, in their I and Q forms, and dated. This information I and Q and the corresponding dates are then sent to the processing device which can implement the method according to the invention. .
• This device can be on board or can be on the ground.
• ADOA type considered is an integrated differential measurement during the evolution in the space of the carrier of the single ESM sensor, between two consecutive measurement positions, for example taking into account the phase difference measured over a large area.
• the measurement of AOA can be a conventional angular measurement, obtained for example by an interferometric device.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Electromagnetism (AREA)
• Computer Networks & Wireless Communication (AREA)
• Radar Systems Or Details Thereof (AREA)
• Position Fixing By Use Of Radio Waves (AREA)

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• 2015
  • 2015-06-17 FR FR1501253A patent/FR3037659B1/fr active Active
• 2016
  • 2016-06-13 WO PCT/EP2016/063521 patent/WO2016202748A1/fr active Application Filing
  • 2016-06-13 US US15/577,295 patent/US10852388B2/en active Active
  • 2016-06-13 EP EP16728700.2A patent/EP3311185A1/de not_active Withdrawn

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