JP2010060303A - Positioning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positioning apparatus which can perform high-precision positioning even for a moving radio source. <P>SOLUTION: The positioning apparatus estimates, using TDOA and FDOA between signals from unknown radio sources 1, 2 received by a plurality of receiving stations 5, 6 through two or more satellites 3, 4, the position of the radio sources. A signal/information processor 7 of the positioning apparatus measures the TDOA and FDOA multiple times, solves an equation for the TDOA and FDOA according to the multiple times measurement results of the TDOA and FDOA with the initial position and velocity of the radio sources as unknown variables on the assumption that the radio sources perform uniform linear motion, and calculates the initial position and velocity of the radio sources. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In the present invention, a time difference of arrival (TDOA) and a frequency difference of arrival (FDOA) are received by a receiving station via a plurality of satellites. More particularly, the present invention relates to a positioning device that estimates the position of a radio wave source, and more particularly to a device that enables highly accurate positioning even for a moving radio wave source.

  2. Description of the Related Art Conventionally, there has been an apparatus as described in Patent Document 1 below as an apparatus for measuring the position of a ground radio wave source using a satellite. This device relates to high accuracy of radio wave source positioning using a satellite. However, as shown in FIG. 6, the positioning principle itself uses a signal from a terrestrial radio wave source 51, which is a positioning object, as a main component of a transmitting antenna. The signals are received by the ground receiving stations 54 and 55 through the satellite 52 that receives the signal from the lobe and the satellite 53 that receives the signal from the side lobe of the transmitting antenna, and the arrival time difference (TDOA) between these signals is received in the signal processor 56. The time difference of arrival (FDOA) and the frequency difference of arrival (FDOA) are obtained, and the position of the radio wave source 51 is specified from the intersection of the equal TDOA curve 57 and the equal FDOA curve 58 on the ground surface.

  Since TDOA is due to a path difference through the two satellites 52 and 53, it is determined by the positional relationship between the target (ground) radio wave source 51, the two satellites 52 and 53, and the receiving stations 54 and 55. Further, since the FDOA is based only on the Doppler shift of the movement of the satellites 52 and 53 if the target radio source 51 is stationary, the target radio source, the two satellites 52 and 53, and the receiving station 54 are used. , 55 and the direction and speed of movement of the two satellites 52, 53. Therefore, the position of the target radio wave source 51 can be specified on the assumption that the three-dimensional elements of the position and velocity of the two satellites 52 and 53 are known.

Japanese Patent No. 3556952

  The conventional positioning method measures FDOA on the assumption that the target radio wave source is stationary. Therefore, when the radio wave source is installed on a ship or the like and moves at an unknown speed, the FDOA has a ground station. There is a problem that Doppler shift due to the movement of the position is added, and this causes an error and the positioning accuracy is greatly deteriorated.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a positioning device that enables highly accurate positioning even for a moving radio wave source.

  This invention is a positioning device for estimating the position of the radio wave source using TDOA and FDOA between signals from unknown radio wave sources received by a plurality of receiving stations via two or more satellites, It is assumed that the signal / information processing device of the positioning device measures TDOA and FDOA multiple times, and that the radio wave source moves linearly at a constant speed, and uses the initial position and velocity of the radio wave source as unknown variables. The positioning apparatus is characterized in that the equation relating to TDOA and FDOA is solved in accordance with a plurality of measurement results and the initial position and velocity of the radio wave source are calculated.

  The present invention enables highly accurate positioning even for a moving radio wave source.

Embodiment 1 FIG.
FIG. 1 is a diagram showing an overall configuration of a positioning apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a mobile radio wave source to be positioned, 2 is the mobile radio wave source after a certain time, 3 is a first satellite that relays the main radio wave from the radio wave source (1, 2), and 4 is a radio wave source. The second satellites 5 and 6 relay the sidelobe radio waves from the terrestrial receiving station receiving the radio waves from the satellites 3 and 4 respectively, and 7 is a signal / information processing device for calculating the radio wave source position from the signals of the receiving stations It is.

  FIG. 2 is a diagram showing an internal configuration of the signal / information processing apparatus 7. 11 is a low noise amplifying means, 12 is a frequency converting means, 13 is an A / D converting means, 14 is a local signal generating means, 15 is a clock trigger signal generating means for A / D conversion, and 16 is a TDOA / FDOA calculation. Means 17, storage means 18, satellite orbit calculation means 19, and positioning calculation means 19.

  Next, the operation will be described. As shown in FIG. 1, the mobile radio wave sources (1, 2) that are positioning targets transmit radio waves toward the first satellite 3. Further, this radio wave is transmitted with weak power in an unintended direction (side lobe) due to the antenna directivity, and is also received by the second satellite 4. The signals respectively received by the first satellite 3 and the second satellite 4 are frequency-converted and retransmitted, and are received by the ground receiving station 5 and the ground receiving station 6, respectively. These received signals are processed by the signal / information processing device 7, and the positioning result of the radio wave source position is output to the output unit or displayed on the display unit (both not shown).

  Next, internal processing of the signal / information processing apparatus 7 will be described. Received signals obtained from satellites 3 and 4 such as communication satellites are amplified by separate low noise amplifying means 11 and converted into IF signals (intermediate frequency) or baseband signals by separate frequency converting means 12. After that, it is converted into a digital signal by separate A / D conversion means 13.

  The local signal supplied to the frequency converter 12 and the clock signal and trigger signal supplied to the A / D converter 13 are supplied by the common local signal generator 14 and the common clock / trigger signal generator 15. To do. However, when the two terrestrial receiving stations 5 and 6 are separated from each other, the local means can be individually used by using a synchronization means using an atomic clock or a GPS standard signal generator, or a correction means including those by digital processing. A signal or a clock trigger signal may be supplied.

  The received signals from the two satellites 3 and 5 converted into digital signals are input to the TDOA / FDOA calculating means 16 and TDOA (arrival time difference) and FDOA (arrival frequency difference) between the two signals are calculated. Acquisition of the received signal and calculation of TDOA and FDOA are performed at regular time intervals or irregularly multiple times, and the TDOA and FDOA for each observation are stored in the storage means 17.

  The calculation of TDOA and FDOA can be performed using, for example, the following correlation calculation.

In the above equation (1), S ₁ (t) is a received signal from the first satellite 3, and S ₂ (t) is a received signal from the second satellite 4. The above equation (1) is calculated while changing τ and f, and τ and f at which the absolute value of the equation (1) becomes the maximum are TDOA and FDOA to be obtained.

  On the other hand, the satellite orbit calculation means 18 calculates the positions and velocities of the two satellites 3 and 4 when TDOA and FDOA received signal data are acquired. This can be calculated from the orbit information of the satellite obtained from a satellite operator or the like. The satellite orbit information may be directly input to the satellite orbit calculation means 18 as shown in FIG. 2A, or may be stored in a predetermined memory (not shown) in advance. Moreover, the method shown by the above-mentioned patent document 1 can also be used.

  The positioning calculation means 19 uses the information on the positions and velocities of the two satellites 3 and 4 obtained from the satellite orbit calculation means 18 and the TDOA and FDOA measured a plurality of times stored in the storage means 17. Calculate the position and velocity of the source (1,2).

  The calculation of position and velocity is based on the assumption that the radio wave source (1,2) is moving in a uniform linear motion while measuring TDOA and FDOA multiple times, and the first TDOA and FDOA are measured. The following simultaneous equations are solved using the initial position and velocity of as unknown variables.

In the above simultaneous equation (2), “·” represents an inner product of vectors, and double || represents a vector length, that is, a norm of a square. The meaning of each variable is as follows.
τ _(k) : Observation TDOA at the k-th measurement
f _(k) : Observation FDOA at the time of the k-th measurement
τ _{D (k)} : Downlink TDOA at the k-th measurement
f _{D (k)} : Downlink FDOA at the time of the k-th measurement
(→) P _(k) : Position vector of the target radio wave source at the time of the k-th measurement
(→) v: Velocity vector of the target radio source (invariant regardless of k)
_{(→) P S1 (k)} : position vector of the k-th measurement at the time of the first satellite
(→) v _{S1 (k)} : velocity vector of the first satellite at the k-th measurement
(→) P _{S2 (k)} : Position vector of the second satellite at the time of the k-th measurement
(→) v _{S2 (k)} : velocity vector of the second satellite at the time of the k-th measurement c: speed of light λ: wavelength at the time of uplink K: total number of measurements

Among the above variables, the observed TDOA and the observed FDOA are known variables because they are obtained from the TDOA / FDOA calculation means 16.
The downlink TDOA and downlink FDOA are calculated from the positions and velocities of the satellites 3 and 4 obtained from the satellite orbit calculation means 18 and the positions of the known ground receiving stations 5 and 6. Therefore, this is also a known variable. The positions of the ground receiving stations 5 and 6 are preset in the positioning calculation means 19, stored in a memory (not shown), or input from the outside as shown by B in FIG.
Further, the position vector of the target radio wave source can be calculated by the following equation at the second and subsequent measurements.

In the above equation (3), t (k) is the time at the k-th measurement.
By substituting the above equation (3) into the simultaneous equation (2), the position vector of the target radio wave source (1, 2) can have only P (1) at the first measurement as an unknown variable. Moreover, when a ship or vehicle is assumed as the mobile radio wave source (1, 2), the radio wave source (1, 2) exists on the ground surface (earth surface), so the height direction (Z direction) is 0 (the coordinate origin is Only x (1) and y (1), which are components in the horizontal plane, are unknown variables.

  In addition, since the velocity vector of the target radio wave source (1, 2) is assumed to be a uniform linear motion, it is a constant value regardless of the number of measurements, and ships and vehicles are used as the mobile radio wave source (1, 2). Assuming that the height direction (Z direction) is zero, only the components Vx and Vy in the horizontal plane are unknown variables.

  The positions and velocities of the satellites 3 and 4 are known because they are obtained from the satellite orbit calculation means 18, and the measurement time, the speed of light, and the wavelength at the time of uplink are also known. Therefore, there are four unknown variables: the horizontal component [x (1), y (1)] of the position vector at the time of the initial measurement of the target radio wave source and the horizontal component [Vx, Vy] of the velocity vector.

  On the other hand, if the number of simultaneous equations (2) is measured twice, it becomes a simultaneous equation consisting of four equations, so the equations can be solved from the relationship with the number of unknown variables, and the initial measurement of the target radio source The time position vector and velocity vector can be obtained. Further, when the measurement is performed three times or more, a larger number of equations can be obtained than the number of unknown variables. Therefore, the position vector and velocity vector of the target radio wave source can be obtained more accurately using the least square principle.

  As described above, this embodiment assumes that the radio wave source moves linearly at a constant speed, and performs positioning calculation using TDOA and FDOA measured multiple times. Therefore, even when the radio wave source moves, the position of the radio wave source is determined. There is a maximum feature that the conventional method can estimate the speed.

  In addition, since TDOA and FDOA are only measured a plurality of times, the satellite receiving equipment and the like may be the same as the conventional one, and there is a feature that it is possible to change only the signal / information processing apparatus. In particular, when the positioning calculation is realized by software, it can be realized only by changing the software.

Embodiment 2. FIG.
In the first embodiment described above, the position and velocity of the radio wave source are estimated on the assumption that the mobile radio wave source is moving at a constant linear velocity. In this embodiment, the mobile radio wave source is It is assumed that a constant-velocity linear motion along the surface of the earth, that is, a circular motion centered on the earth.

  In order to solve the simultaneous equations (2) relating to TDOA and FDOA measured a plurality of times with high accuracy, it is preferable that each equation is as independent as possible. When the satellite is a geostationary satellite, the position and velocity of the satellite change in a cycle of 24 hours. Therefore, in order to obtain an independent equation, it is necessary to repeatedly measure TDOA and FDOA over several hours. During this time, since the ship (radio wave source) travels several tens of kilometers or more, the spherical nature of the ground surface may not be negligible. Therefore, in this embodiment, it is assumed that the moving radio wave source moves at a constant linear velocity along the surface of the earth.

  The difference between the first embodiment and the second embodiment is only the positioning calculation method. Therefore, the configuration of the positioning device is basically the same as that of the first embodiment, and only the positioning calculation method will be described.

  The operation of this embodiment will be described below. In the positioning calculation, in this embodiment, the moving radio wave source (1, 2) assumes a circular motion around the earth. In this case, it is convenient to use a fixed coordinate system centered on the earth as the coordinate system used for positioning calculation. The velocity vector V (k) of the radio wave source (1, 2) moving at a constant speed along the ground surface (earth surface) in this coordinate system is represented by the position vector P (k) and the velocity vector V ( It can be expressed using an angular velocity vector ω perpendicular to k).

  In the above equation, “x” represents the outer product of vectors.

  FIG. 3 shows the relationship between the position vector of the radio wave source, the velocity vector, and the angular velocity vector. In FIG. 3, 21 is the center of the earth, 22 is an angular velocity vector, 23 is a position vector of the radio wave source at the k-th measurement, and 24 is a velocity vector of the radio wave source at the k-th measurement.

  When the radio wave source moves at a constant linear velocity on the ground surface, the angular velocity vector 22 is constant regardless of k. Therefore, each element is expressed by the following equation with a value not depending on k as follows.

  In addition, as shown below, the position vector P (k) (k = 2, 3,..., K) of the radio wave source at the second and subsequent measurements is the position vector P (1) at the first measurement. And the angular velocity vector ω can be expressed as follows:

  On the other hand, the conditions necessary for positioning calculation are as follows.

  In the above simultaneous equations (7), R is the average radius of the earth.

  The third equation of the simultaneous equation (7) is an equation for ensuring that the radio wave source is on the ground surface. The fourth equation is an equation for ensuring that the angular velocity vector is perpendicular to the position vector of the radio wave source.

  By substituting the above equation (6) into the position vector P (k) of the radio wave source and the above equations (4) and (6) into the velocity vector V (k), the simultaneous equation (7) Can be expressed using the position vector P (1) and the angular velocity vector ω.

  Therefore, the unknown variables are the position vector P (1) = [x (1), y (2), z (3)] at the first measurement of the radio wave source, and the angular velocity vector ω = [u that is constant regardless of k. , V, w], a total of six.

  On the other hand, the number of simultaneous equations (7) is 2K + 2 with K being the total number of measurements. Therefore, if two measurements are made, it becomes a simultaneous equation consisting of six equations, so the equation can be solved from the relationship with the number of unknown variables, and the position vector and velocity vector at the time of the first measurement of the target radio wave source can be obtained. Can do. Further, when the measurement is performed three times or more, a larger number of equations can be obtained than the number of unknown variables. Therefore, the position vector and velocity vector of the target radio wave source can be obtained more accurately using the least square principle.

  In this embodiment, it is assumed that the radio wave source moves at a constant speed along the ground surface, and positioning calculation is performed using the TDOA and FDOA measured multiple times. Therefore, even when the radio wave source moves, the position and speed of the radio wave source There is a feature that can be estimated. In addition, since it is assumed that the radio wave source moves at a constant speed along the surface of the earth, it can be applied to a case where the radio wave source moves significantly due to a long measurement time compared to a case where the radio wave source is assumed to be a simple constant linear motion. There is.

  In this embodiment, the positioning calculation is performed on the assumption that the earth is a sphere, but it can also be calculated as an ellipsoid. In this case, there is an advantage that the radio wave source position and speed can be obtained more precisely.

Embodiment 3 FIG.
In the first embodiment described above, the position and velocity of the mobile radio wave source are estimated using two satellites. In this embodiment, three or more satellites are used, and TDOA and FDOA are used for each measurement. It is to change the combination of satellites that calculate

  FIG. 4 is a diagram showing the overall configuration of the positioning apparatus according to this embodiment. In FIG. 4, 31 is a mobile radio wave source to be positioned, 32 is the mobile radio wave source after a certain time, 33 is a first satellite that relays the main radio wave from the radio wave source, and 34 is a sidelobe radio wave from the radio wave source. , A third satellite that relays sidelobe radio waves from a radio wave source, 36 a ground receiving station that receives radio waves from the first satellite 33, and 37 a second satellite 34. A terrestrial receiving station 38 that receives radio waves from the third satellite 35 by switching for each measurement, and 38 is a signal / information processing device that calculates a radio wave source position from the signal of the receiving station. The configuration of the signal / information processing device 38 is basically the same as that shown in FIG.

  Next, the operation will be described. In order to solve the simultaneous equations (2) or (7) relating to TDOA and FDOA measured a plurality of times with high accuracy, it is better that each equation is as independent as possible. However, when the satellite is a geostationary satellite, the position and velocity of the satellite change in a cycle of 24 hours, so that the measurement interval between TDOA and FDOA needs to be several hours in order to obtain an independent equation. If the ship or the like, which is the target radio wave source (31, 32), accelerates or decelerates or changes direction during the measurement over several hours, the constant velocity linear motion assumed in the first embodiment, There is a problem that it cannot be regarded as a uniform motion along the ground surface assumed in the second mode.

  Therefore, in this embodiment, for each measurement, the satellite that receives the sidelobe radio waves is switched to another satellite by changing the direction of the antenna of the ground receiving station (for example, 37). That is, switching between the satellites 34 and 35 is performed. For example, as shown in FIG. 4, TDOA and FDOA are measured by a combination of the first satellite 33 and the second satellite 34 for a certain measurement, and the first satellite 33 and the third satellite are used for the next measurement. TDOA and FDOA are measured in combination with the satellite 35.

  The positioning calculation is performed only by substituting the position and velocity of the satellite used for the TDOA and FDOA measurement in the formula (2) of the first embodiment and the formula (7) of the second embodiment. This can be performed in the same manner as in Embodiment Mode 2.

  Since the position and speed of the satellite change by switching the satellites in this way, a highly independent equation can be obtained even if TDOA and FDOA are measured at short intervals that change the direction of the antenna of the receiving station. Therefore, measurement can be performed in a short time, and the position and speed of the radio wave source can be adjusted even if the ship equipped with the radio wave source is accelerating / decelerating and changing direction and the time that can be regarded as constant-velocity linear motion is short. There is an advantage that it is easy to estimate.

  In this embodiment, the terrestrial receiving station uses only two terrestrial receivers to switch satellites. However, if three terrestrial receiving stations can be used, two sets of TDOA and FDOA may be measured simultaneously. In that case, there is an advantage that the position and speed of the target radio wave source can be estimated by one measurement. Further, for example, the low noise amplifying means 11, the frequency converting means 12, and the A / D converting means 13 of FIG.

Embodiment 4 FIG.
In Embodiments 1 and 2, since it is assumed that the target radio wave source is moving at a constant linear velocity during a plurality of TDOA and FDOA measurements used for one positioning calculation, the target radio wave source is accelerated / decelerated. If you perform or change direction, the positioning accuracy may deteriorate. This embodiment is a measure for dealing with it.

  FIG. 5 is a diagram for explaining the outline of this embodiment. Reference numeral 41 denotes the movement path of the target radio wave source, 42 denotes the position of the target radio wave source at the time of TDOA / FDOA measurement in the (m−4) th (m is the TDOA / FDOA measurement times at the moment when the target radio wave source changes the moving direction), 43 Is the position of the target radio wave source at the (m-3) th TDOA / FDOA measurement, 44 is the position of the target radio wave source at the (m-2) th TDOA / FDOA measurement, and 45 is the (m-1) th time. The position of the target radio wave source at the time of TDOA / FDOA measurement, 46 is the position of the target radio wave source at the time of the TDOA / FDOA measurement of the mth time, 47 is the (m-4), (m-3), (m-2) th time. Positioning results calculated using a set of TDOA and FDOA for measurement, 48 are positioning results calculated using a set of TDOA and FDOA for measurement (m-3), (m-2), and (m-1) times , 49 are (m-2), (m-1), and T of measurement at the mth time. Positioning calculated using a set of OA and FDOA results, 50 is the difference of the positioning result of the 48 positioning results and 49.

  Next, the operation will be described. In this embodiment, the positioning calculation shown in Embodiment 1 and Embodiment 2 is performed in time series while overlapping the measurement results of TDOA and FDOA. For example, as shown in FIG. 4, after the positioning calculation is performed using the measured TDOA and FDOA at the (m−4), (m−3), and (m−2) times, the next calculation is (m− 3), (m-2), and (m-1) The measurement is performed using TDOA and FDOA.

  If the target radio wave source is moving at a constant linear velocity, the positioning calculation results coincide as shown by 47 and 48 in FIG. 5 between the results of positioning calculation using overlapping sets of TDOA and FDOA.

  On the other hand, if the set of TDOA and FDOA for which positioning has been calculated includes the moment when the target radio wave source has changed its direction of movement or acceleration / deceleration, it will be constant velocity as shown in the positioning calculation result of 49 in FIG. It does not coincide with the positioning calculation result 48 in the case of linear motion.

  In this way, the positioning results calculated using overlapping sets of TDOA and FDOA are compared. If there is a certain difference or more, there is a possibility that the target radio wave source has changed the direction of movement or accelerated / decelerated during that time. Judge that there is, and reject the positioning result that seems to be incorrect.

  Thus, according to this embodiment, since the moment when the movement of the target radio wave source deviates from the constant velocity linear motion can be detected, even if there is a moment when the movement of the target radio wave source deviates from the constant velocity linear motion, the constant velocity linear There is an advantage that only a moving part can be selected and a correct positioning result can be output.

  Although the positioning device has been described in the above description, it is needless to say that the present invention may include a positioning method performed by these positioning devices.

It is a figure which shows the whole structure of the positioning apparatus by one Embodiment of this invention. It is a figure which shows the internal structure of the signal and information processing apparatus of FIG. It is a figure which shows the relationship between the position vector of the radio wave source concerning Embodiment 2 of this invention, a velocity vector, and an angular velocity vector. It is a figure which shows the whole structure of the positioning apparatus by Embodiment 3 of this invention. It is a figure for demonstrating the outline | summary of the positioning apparatus by Embodiment 4 of this invention. It is a figure for demonstrating this kind of conventional positioning method.

Explanation of symbols

  1, 2, 31, 32 Mobile radio wave source, 3, 4, 33, 34, 35 Satellite, 5, 6, 36, 37 Ground receiving station, 7, 38 Signal / information processing device, 11 Low noise amplification means, 12 Frequency Conversion means, 13 A / D conversion means, 14 local signal generation means, 15 clock trigger signal generation means, 16 TDOA / FDOA calculation means, 17 storage means, 18 satellite orbit calculation means, 19 positioning calculation means, 22 angular velocity vector, 23 Radio wave source position vector, 24 radio wave source velocity vector.

Claims (4)

A positioning device that estimates the position of the radio wave source using TDOA and FDOA between signals from unknown radio wave sources received by a plurality of receiving stations via two or more satellites,
Positioning device signal / information processing device
TDOA and FDOA are measured a plurality of times, and it is assumed that the radio wave source moves linearly at a constant speed. The initial position and velocity of the radio wave source are unknown variables. A positioning device which solves according to the measurement result and calculates the initial position and velocity of the radio wave source. A positioning device that estimates the position of the radio wave source using TDOA and FDOA between signals from unknown radio wave sources received by a plurality of receiving stations via two or more satellites,
Positioning device signal / information processing device
Assuming that TDOA and FDOA are measured multiple times, and that the radio source is moving at a constant speed along the surface of the earth, the initial position and velocity of the radio source, or the initial position and angular velocity around the earth are defined as unknown variables. A positioning apparatus characterized by solving an equation relating to TDOA and FDOA according to a plurality of measurement results of TDOA and FDOA, and calculating an initial position and velocity of the radio wave source.   When measuring TDOA and FDOA multiple times, use signals from different combinations of satellites for each measurement, increase the independence of equations related to TDOA and FDOA, and calculate the position and velocity of the radio wave source The positioning device according to claim 1 or 2.   The combination of TDOA and FDOA measured several times is used to perform positioning calculation with different combinations partially overlapped, and the validity of the positioning calculation result is judged by comparing the positioning calculation results. 2. The positioning device according to 2.

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