KR101733033B1 - Method for estimating position using bistatic range - Google Patents

Abstract

The present invention relates to an apparatus and a method to estimate a location by using a bistatic range, capable of mutually associating signals reflected from the same target among signals received in a receiver. According to the present invention, the method comprises the following steps of: receiving reflective signals which are a signal source emitted from each transmitter and reflected from a plurality of targets, and using the received reflective signals to measure bistatic ranges for each transmitter; using the measured bistatic ranges of each transmitter, a preset transmitter location, and a preset receiver location to generate lines of position (LOP) by the bistatic range of each transmitter; and confirming a cross position of the generated LOPs of each transmitter to generate a correlation among the signals of each transmitter with respect to the same target, and estimating the location of the same target from the confirmed cross position in accordance with the generated correlation. The measure step measures the bistatic ranges and a bistatic speed from the received reflective signals in every preset time.

Description

[0001] METHOD FOR ESTIMATING POSITION USING BISTATIC RANGE [0002]

The present invention relates to a position estimation technique, and more particularly, to a position estimation technique for estimating a position of a target by correlating signals reflected from the same target among signals received by a receiver using bistatic ranges by transmitter And a position estimation method using a bistatic distance.

The aircraft has a stellar function to lower the radar cross section (RCS) with a paint and shape that minimizes reflection of the radar signal in order to avoid detection by the radar.

On the other hand, since the communication signal is different from the radar signal in the frequency band, the signal reflection from the air vehicle is relatively large. Accordingly, a passive coherent location (PCL) system, which is a receiver system using a principle that a communication band signal (for example, an FM signal) such as a broadcasting station signal is radiated and reflected directly to a flight body and a broadcasting station signal is directly studied.

In a conventional passive system, the signal source itself emitted from the target source is used. However, the PCL system uses a signal from a third radiation source (e.g., a broadcasting station) reflected from the target circle without emitting a signal in the target circle itself.

Therefore, in the conventional passive system, it is impossible to detect the position of the target circle unless a signal is emitted from the target circle.

In this PCL system, when a plurality of aviation bodies simultaneously appear and disappear, it is impossible to know the position of a reflected signal from a specific broadcasting station, which is reflected from any of the enemy flight vehicles when the receiver receives the reflected signal.

On the other hand, such a receiver technology is not studied in the domestic market. PCL systems are being studied in the advanced defense industry. However, even in such a PCL system, there is no specific method to find out that the reflection signals of various broadcasting stations are the same target (threat) when there are various aviation bodies.

Embodiments of the present invention provide a method and apparatus for estimating a position using bistatic distance, which can correlate signals reflected from the same target (e.g., a flying object) among signals received at a receiver using bistatic ranges by transmitter, Method.

Specifically, embodiments of the present invention use a bistatic distance indicating a time difference between a reflected signal reflected by a receiver and a signal received without reflection to determine whether a signal received by a receiver is reflected on a target And a position estimation method using a bistatic distance capable of estimating a position of the target.

Further, in the embodiments of the present invention, the position of the target is estimated by correlating the signals received from each broadcasting station in order to know the signals received from the same target for position estimation in the PCL system, A position estimation method using a bistatic distance, which can be provided as an initial position value of a nonlinear position estimation algorithm for position estimation, is provided.

According to a first aspect of the present invention, there is provided a method comprising: receiving a reflected signal from a plurality of targets, the signal source radiated by each transmitter; and measuring transmitter-specific bistatic ranges using the received reflected signals ; Generating a line of position (LOP) by a bistatic distance by a transmitter using the measured bistatic distances for each transmitter, a predetermined transmitter position and a predetermined receiver position; And generating the correlation of the transmitter-specific signals for the same target by checking the generated intersection points of the position lines for each transmitter and estimating the position of the same target from the identified intersection points in accordance with the generated correlation Wherein the measuring step may include a bistatic distance measurement method for measuring bistatic distances and bistatic velocities at predetermined time intervals from the received reflected signals.

The step of measuring the bistatic distances may include receiving reflected signals reflected from a plurality of targets by a signal source radiated by each transmitter of a broadcasting station using different frequency bands.

The generating of the position lines may include: plotting position lines using the measured bistatic distances, a predetermined transmitter position and a predetermined receiver position; Performing quantization on the rendered position lines according to the X-axis and Y-axis resolutions; And accumulating and plotting the quantized position lines according to the number of cases.

The step of visualizing the position lines may include the steps of: calculating a distance between the transmitter and the receiver by subtracting a distance between the transmitter and the receiver from the measured bistatic distances, . ≪ / RTI >

The quantization may be performed by setting the resolution between cells in the X and Y axes to a predetermined distance such that the displayed position lines are displayed at a resolution of a predetermined distance.

The step of estimating the position of the same target can generate a correlation of signals for each transmitter for the same target by checking the intersections where the position lines for each transmitter are overlapped by the number of transmitters.

According to a second aspect of the present invention, there is provided a method comprising: receiving a reflected signal from a plurality of targets, the signal source being emitted from each transmitter; and measuring bistatic ranges by transmitter using the received reflected signals Generating a line of position (LOP) according to a bistatic distance by a transmitter using the measured bistatic distances of the transmitter, a predetermined transmitter position and a predetermined receiver position, Generating a correlation of a signal for each transmitter with respect to the same target by checking an intersection of the lines and estimating a position of the same target from the identified intersection according to the generated association; And calculating a position of the same target using the estimated position of the same target as an initial position value of a predetermined nonlinear least squares method or an extended Kalman filter, A position estimation method using bistatic distances to measure bistatic distances and bistatic velocities at predetermined time intervals can be provided.

Embodiments of the present invention may utilize transmitter-specific bistatic ranges to correlate signals reflected from the same target (e.g., a flight) among the signals received at the receiver.

Specifically, embodiments of the present invention use a bistatic distance indicating a time difference between a reflected signal reflected by a receiver and a signal received without reflection to determine whether a signal received by a receiver is reflected on a target And the position of the target can be estimated.

Further, in the embodiments of the present invention, the position of the target is estimated by correlating the signals received from each broadcasting station in order to know the signals received from the same target for position estimation in the PCL system, It can be provided as an initial position value of a non-linear position estimation algorithm for position estimation.

1 is a block diagram of a PCL system including a position estimating apparatus using a bistatic distance according to an embodiment of the present invention.
2 is a diagram illustrating a bistatic distance between a transmitter, a receiver, and a target according to an exemplary embodiment of the present invention.
3 is a diagram illustrating the geometry of a transmitter, receiver, and targets to which an embodiment of the present invention is applied.
4 is an exemplary diagram illustrating bistatic distances and bistatic velocities measured for each transmitter according to an embodiment of the present invention.
5 is an explanatory diagram of a position line having a shape of an ellipsoid according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating quantization of a position line according to an X-axis and a Y-axis resolution according to an embodiment of the present invention.
FIG. 7 is a diagram for classifying bistatic distances for each transmitter according to the number of cases according to an embodiment of the present invention.
FIG. 8 is a diagram illustrating the cumulative operation of position lines according to a bistatic distance for each transmitter according to an embodiment of the present invention. Referring to FIG.
9 is a flowchart illustrating a method of estimating a position using a bistatic distance according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention will be described in detail with reference to the portions necessary for understanding the operation and operation according to the present invention. In describing the embodiments of the present invention, description of technical contents which are well known in the art to which the present invention belongs and which are not directly related to the present invention will be omitted. This is for the sake of clarity of the present invention without omitting the unnecessary explanation.

In describing the constituent elements of the present invention, the same reference numerals may be given to constituent elements having the same name, and the same reference numerals may be given to different drawings. However, even in such a case, it does not mean that the corresponding component has different functions according to the embodiment, or does not mean that it has the same function in different embodiments, and the function of each component is different from that of the corresponding embodiment Based on the description of each component in FIG.

1 is a block diagram of a PCL system including a position estimating apparatus using a bistatic distance according to an embodiment of the present invention.

As shown in FIG. 1, a passive coherent location (PCL) system including a position estimating apparatus 100 using a bistatic distance according to an embodiment of the present invention includes a plurality of transmitters 11, A receiver 12 and a position estimating apparatus 100. [

1, target 1 101 includes target # 1, target # 2, and transmitter 11 is shown as including transmitter # 1 and transmitter # 2, And the number of specific transmitters.

First, the transmitter 11 emits a signal source to the target 101, targets # 1 and # 2. For example, the target 101 may include a flying object or the like. Here, the transmitter # 1 emits a signal source having the frequency f _A of the broadcasting station, and the transmitter # 2 transmits the signal source having the frequency f _{B of the} broadcasting station different from the frequency f _A of the transmitter # 1 to a plurality of targets, # 1 and # 2.

The receiver 12 receives the reflected signals reflected from the plurality of targets 101 by a signal source radiated from each transmitter, transmitter # 1, transmitter # 2. Here, the receiver 12 includes a reflective antenna and a reference antenna. The reflection antenna receives the reflection signal # 1 and the reflection signal # 2. The reference antenna receives the reference signal. The receiver 12 can receive reflected signals reflected from a plurality of targets 101 from a signal source emitted from each transmitter 11 of a broadcasting station using different frequency bands.

The position estimating apparatus 100 according to the embodiment of the present invention uses a bistatic distance indicating a time difference between a reflection signal reflected by the receiver 12 and a signal received without reflection, The position estimating apparatus 100 can use this bistatic distance to correlate the signal received at the receiver 12 with which target is the reflected signal and to estimate the position of the target 101. [

The specific configuration and operation of each component of the position estimation apparatus 100 of FIG. 1 will be described below.

1, the position estimating apparatus 100 includes a bistatic distance measuring unit 110, a position line generating unit 120, and a position estimating unit 130. As shown in FIG. Here, the position estimation apparatus 100 may further include a position calculation unit 140.

The bistatic distance measuring unit 110 measures the bistatic ranges of each transmitter using the reflection signals received at the receiver 12. [ Here, the bistatic distance measuring unit 110 may measure bistatic distances and bistatic velocities from the reflection signals received at the receiver 12 every predetermined time (e.g., 5 seconds). At this time, the bistatic distance represents the time difference between the reflected signal reflected by the receiver 12 and the received signal without reflection.

The position line generation unit 120 generates a position line (LOP) according to the bistatic distance by transmitter using the bistatic distances for each transmitter measured at the bistatic distance measuring unit 110, the predetermined transmitter position, Line of position.

The position estimating unit 130 checks the intersection points of the position lines generated by the position line generator 120 with respect to each transmitter to generate a signal-to-transmitter correlation for the same target. Then, the position estimating unit 130 estimates the position of the same target from the identified intersection according to the generated association.

Here, the position estimator 130 identifies the intersections where the position lines of the transmitter generated by the position line generator 120 are overlapped by the number of transmitters, and generates the correlation of signals for each transmitter for the same target. The position estimating unit 130 may estimate the intersection points overlapping by the number of transmitters as the positions of the same target.

The position line generation unit 120 may include a position line diagram unit 121, a quantization unit 122, and an accumulation unit 123.

The positional line diagramming unit 121 uses the bistatic distances measured by the bistatic distance measuring unit 110 to plot the positional lines using predetermined transmitter positions and preset receiver positions. The position plotting section 121 has two intermediate points, which are a predetermined transmitter position and a predetermined receiver position, and is positioned between the transmitter 11 and the receiver 12 at bistatic distances measured at the bistatic distance measuring section 110 The position line having the shape of the ellipsoid can be schematized.

Then, the quantization unit 122 quantizes the positional lines drawn by the positional line diagramming unit 121 according to the X-axis and Y-axis resolutions. At this time, the quantization unit 122 converts the resolution between the cells of the X and Y axes to a predetermined distance (for example, 4 km) so that the position lines drawn in the position line diagramming unit 121 are displayed at a set distance For example, 4 km) to perform quantization.

The cumulative diagramming unit 123 accumulates and graphs the position lines on which quantization is performed by the quantization unit 122 according to the number of cases.

As described above, the position estimation apparatus 100 according to the embodiment of the present invention is applied when the target vehicle is two or more, that is, a plurality of targets. The position estimation apparatus 100 associates the signals reflected from the same target among the signals reflected from the target 101 received through the reflective antenna. Thus, the position estimating apparatus 100 can estimate the position of the target 101. [

As shown in FIG. 1, the position estimating apparatus 100 may further include a position calculating unit 140 that calculates a position in accordance with a non-linear position estimation algorithm for accurate position estimation in the PCL system 100.

The position calculation unit 140 may calculate the position of the same target by using the position of the same target estimated by the position estimation unit 130 as the initial position value of the preset nonlinear least squares method or the extended Kalman filter.

2 is a diagram illustrating a bistatic distance between a transmitter, a receiver, and a target 101 according to an embodiment of the present invention.

The distance (R _T), the target 101 and the receiver 12 between the distance (R _R) and the transmitter 11 and the receiver baseline distance (L) between 12 between the transmitter 11 and the target 101, Fig. 2.

The bistatic distance measuring unit 110 receives the signal reflected by the transmitter-specific target and measures the bistatic distance according to the following equation (1).

[Equation 1]

Bistatic Range = R _T + R _R - L

Here, Bistatic Range is bistatic distance, R _T is the distance between the transmitter 11 and the target (101), R _R is the distance between the target 101 and the receiver 12, L is a transmitter 11 and a receiver 12 Lt; / RTI >

3 is a diagram illustrating the geometry of a transmitter, receiver 12 and targets to which an embodiment of the present invention is applied.

Target # 1, target # 2 and target # 3 are shown on the X and Y axes together with the transmitter 11 and the receiver 12, as shown in FIG.

On the X and Y axes, the receiver 12 is represented by an equilateral triangle 'Rx', and the transmitter 11 is represented by 'Tx # 1 to 3' by inverted triangles.

The receiver 12 is located at the midpoint of the X and Y axes and the three transmitters 11 are spaced apart from the receiver 12 in different directions. 3 also shows the PCL geometry for target # 1, target # 2, and target # 3, which are centered at the receiver 12.

4 is an exemplary diagram illustrating bistatic distances and bistatic velocities measured for each transmitter according to an embodiment of the present invention.

As shown in FIG. 4, the bistatic measuring unit can measure the bistatic distance and the bistatic velocity from the signal received from the individual transmitter 11 every predetermined time (for example, 5 seconds).

In the case of the FM (Frequency Modulation) signal, the receiver 12 uses different frequency bands for each broadcasting station. Therefore, the receiver 12 should be able to distinguish which signal is received from a certain transmitter.

However, the receiver 12 will not know which signal is reflected from which target. For example, when looking at the bistatic distance and the bistatic speed for the TX # 1 as the receiver # 1, there are three kinds of red curves. This represents the measured value for each of the three targets. However, the receiver can not know from which target the measured value of the reflected signal is.

In this situation, the position estimation apparatus 100 according to the embodiment of the present invention uses the bistatic distances per transmitter, the transmitter position and the receiver position to calculate a line of position (LOP) . Thereby, the position estimation apparatus 100 can confirm which target is the measurement value of the reflected signal reflected from the target.

5 is an explanatory diagram of a position line having a shape of an ellipsoid according to an embodiment of the present invention.

Position generator 120 generates position lines 501 by transmitter-specific bistatic distance. In addition, the position line generation unit 120 stores data capable of illustrating the position line 501.

As shown in Fig. 5, the position line 501 has two center points, which are a predetermined transmitter position and a predetermined receiver position.

Position generator 120 generates a position line 501 having the shape of an ellipsoid through a fixed value C (bistatic range - L). Here, C can be calculated by subtracting the baseline distance between the transmitter 11 and the receiver 12 from the bistatic distance, as shown in the following equation (2).

&Quot; (2) "

C = Bistatic Range + L = R _T + R _R

Here, C is obtained by subtracting the base line distance between the transmitter 11 and the receiver 12 in bistatic distance value, Bistatic Range is the distance between the bistatic distance, R _T is the transmitter 11 and the target (101), R _R is The distance between the target 101 and the receiver 12, L, represents the baseline distance between the transmitter 11 and the receiver 12.

FIG. 6 is a diagram illustrating quantization of a position line according to an X-axis and a Y-axis resolution according to an embodiment of the present invention.

As shown in FIG. 6, the quantization unit 122 may set the resolution between cells in the X and Y axes to a predetermined distance (for example, 4 km).

Then, the shape 601 of the ellipsoid with respect to the position line can be expressed with a resolution of a predetermined distance (e.g., 4 km).

FIG. 7 is a diagram for classifying bistatic distances for each transmitter according to the number of cases according to an embodiment of the present invention.

The cumulative diagramming unit 123 accumulates and quantizes the position lines quantized by the quantizing unit 122 according to the number of cases.

For example, the position estimating apparatus 100 performs quantization according to the number of cases of bistatic distances per transmitter, for example, three transmitters, one receiver, and three targets. For one transmitter, it has bistatic distances for each of the three targets. For example, transmitter # 1 has three bistatic distances: bistatic distance # 1, bistatic distance # 2, bistatic distance # 3. Transmitter # 2 also has three bistatic distances: bistatic distance # 1, bistatic distance # 2, bistatic distance # 3. Transmitter # 3 also has three bistatic distances: bistatic distance # 1, bistatic distance # 2, bistatic distance # 3.

Then, the position estimating apparatus 100 accumulates the positions of the quantization lines according to the number of cases, and stores the positions of the intersections where the position lines are overlapped by the number of transmitters.

The position estimating apparatus 100 may determine that it has an association between signal sources by confirming that it matches the transmitter number condition. At this time, crossing points overlapping by the number of transmitters can also be used as initial positions of the target.

FIG. 8 is a diagram illustrating the cumulative operation of position lines according to a bistatic distance for each transmitter according to an embodiment of the present invention. Referring to FIG.

In FIG. 8, an accumulative calculation of LOPs by a bistatic distance for each transmitter is illustrated.

For example, '# 2 / # 3 / # 1' means the position line (LOP) of the signal # 2 emitted by the transmitter # 1, the position line (LOP) of the signal # 3 emitted by the transmitter # , And the position line (LOP) of the signal # 1 radiated by the transmitter # 3.

As shown in FIG. 8, in the case of the position line using the bistatic range for the same target in each channel, only the intersection point of three ellipses in the case of '# 1 / # 1 / # 1' (801) .

Therefore, the position estimation apparatus 100 according to the embodiment of the present invention can determine whether or not the correlation of data on the same target in the case of '# 1 / # 1 / # 1' in which the number of transmitters, an association relationship can be created. At this time, the intersection point of the ellipses can be used as the initial position value of the target circle.

9 is a flowchart illustrating a method of estimating a position using a bistatic distance according to an embodiment of the present invention.

The receiver 12 receives the reflected signals reflected from the plurality of targets 101 by a signal source emitted from each transmitter 11 (S901).

Then, the position estimating apparatus 100 measures the bistatic distances by the transmitter using the reflection signals received by the receiver 12 (S902).

The position estimating apparatus 100 then uses the measured bistatic distances for each transmitter, the predetermined transmitter position and the predetermined receiver position to graphically represent the position lines (LOPs) by the transmitter-by-bistatic distance and store the diagram data (S903). Here, the position estimating apparatus 100 has two midpoints, which are a predetermined transmitter position and a predetermined receiver position, and a value obtained by subtracting the distance between the transmitter 11 and the receiver 12 at the measured bistatic distances A position line having a shape can be schematized.

Then, the position estimation apparatus 100 quantizes the illustrated position lines according to the X-axis and Y-axis resolutions (S904). Here, the position estimation apparatus 100 performs quantization by setting the resolution between the cells of the X and Y axes to a predetermined distance so that the illustrated position lines are displayed at a resolution of a predetermined distance.

The position estimation apparatus 100 accumulates and quantizes the quantized position lines according to the number of cases (S905).

The position estimation apparatus 100 confirms whether there is an intersection point where the number of position lines for each transmitter overlaps by the number of transmitters (S906).

If it is determined at step S906 that there is a crossing point at which the number of position lines for each transmitter overlaps the number of transmitters, the position estimating apparatus 100 generates a correlation of signals for each transmitter for the same target at step S907.

Then, the position estimating apparatus 100 estimates the position of the same target from the intersection point where the position lines for each transmitter are overlapped by the number of transmitters (S908).

The position estimation apparatus 100 may calculate the position of the same target using the estimated position of the same target as the initial position value of the predetermined nonlinear least squares method or the extended Kalman filter (909).

Here, since the position estimation algorithm of the target circle has a nonlinear model of the bistatic distance of the PCL position estimation, the position calculation unit 140 performs the position estimation using the nonlinear least squares method or the EKF (Extended Kalman Filter) can do. At this time, if an initial value of an appropriate position is not specified, there is a tendency to estimate or diverge an erroneous target. Therefore, it is important to estimate the position of the target circle even within a predetermined error range.

On the other hand, if it is determined in step S906 that there is no intersection point where the number of position lines for each transmitter is overlapped by the number of transmitters, the position estimating apparatus 100 does not generate the correlation of signals for each transmitter for the same target in step S910. That is, since the position estimation apparatus 100 is not a signal for each transmitter for the same target, it does not constitute an association.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or essential characteristics thereof. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

10: PCL system
11: Transmitter
12: receiver
101: Target
100:
110: bistatic distance measuring unit
120: Position line generation unit
121: Position line drawing section
122: Quantization unit
123: Cumulative diagramming unit
130:
140:

Claims (12)

Receiving reflected signals from a plurality of targets from a source radiated by each transmitter and using the received reflected signals to measure transmitter-specific bistatic ranges;
Generating a line of position (LOP) by a bistatic distance by a transmitter using the measured bistatic distances for each transmitter, a predetermined transmitter position and a predetermined receiver position; And
Generating a correlation of signals for each transmitter for the same target by checking the generated intersection points of the position lines for each transmitter and estimating a position of the same target from the identified intersection according to the generated correlation;
Wherein the measuring step measures bistatic distances and bistatic velocities from the received reflected signals at predetermined time intervals,
The step of generating the position lines may include the steps of: plotting position lines using the measured bistatic distances, a predetermined transmitter position, and a predetermined receiver position, and displaying the illustrated position lines at a predetermined distance resolution , Performing quantization by setting a resolution between cells in the X and Y axes to a preset distance, and accumulating and plotting the quantized position lines according to the number of cases, . The method according to claim 1,
Wherein measuring the bistatic distances comprises:
A method for estimating a position using a bistatic distance in which a signal source radiated from each transmitter of a broadcasting station using different frequency bands receives reflected signals reflected from a plurality of targets. delete The method according to claim 1,
The step of visualizing the position lines comprises:
A position using a bistatic distance having two midpoints, a predetermined transmitter position and a predetermined receiver position, and drawing a position line having a shape of an ellipsoid in which the distance between the transmitter and the receiver is subtracted from the measured bistatic distances Estimation method. delete The method according to claim 1,
Wherein estimating the position of the same target comprises:
And generating a correlation of signals for each transmitter with respect to the same target by checking an intersection point where the generated position lines for each transmitter are overlapped by the number of transmitters. Receiving reflected signals from a plurality of targets from a source radiated by each transmitter and using the received reflected signals to measure transmitter-specific bistatic ranges;
Generating a line of position (LOP) by a bistatic distance by a transmitter using the measured bistatic distances for each transmitter, a predetermined transmitter position and a predetermined receiver position;
Generating a correlation of signals for each transmitter for the same target by checking the generated intersection points of the position lines for each transmitter and estimating a position of the same target from the identified intersection according to the generated correlation; And
Calculating a position of the same target using the estimated position of the same target as an initial position value of a predetermined nonlinear least squares method or an extended Kalman filter;
Wherein the measuring step measures bistatic distances and bistatic velocities from the received reflected signals at predetermined time intervals,
The step of generating the position lines may include the steps of: plotting position lines using the measured bistatic distances, a predetermined transmitter position, and a predetermined receiver position, and displaying the illustrated position lines at a predetermined distance resolution , Performing quantization by setting a resolution between cells in the X and Y axes to a preset distance, and accumulating and plotting the quantized position lines according to the number of cases, . 8. The method of claim 7,
Wherein measuring the bistatic distances comprises:
A method for estimating a position using a bistatic distance in which a signal source radiated from each transmitter of a broadcasting station using different frequency bands receives reflected signals reflected from a plurality of targets. delete 8. The method of claim 7,
The step of visualizing the position lines comprises:
A position using a bistatic distance having two midpoints, a predetermined transmitter position and a predetermined receiver position, and drawing a position line having a shape of an ellipsoid in which the distance between the transmitter and the receiver is subtracted from the measured bistatic distances Estimation method. delete 8. The method of claim 7,
Wherein estimating the position of the same target comprises:
And generating a correlation of signals for each transmitter with respect to the same target by checking an intersection point where the generated position lines for each transmitter are overlapped by the number of transmitters.

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