JPH0443981A - Depression and elevation angle estimating method - Google Patents

Abstract

PURPOSE:To estimate the depression/elevation angle of a target signal source by estimating the depression/elevation angle of the arrival of a signal from the peak of the depression/elevation characteristic of a residual level and removing the influence of a noise. CONSTITUTION:Subordinate horizontal phase matching beams 41-1, 41-2, 41-4, and 41-5 are generated even nearby the horizontal azimuth psi where the signal source 43 is present and differences between the level of a main horizontal phase matching beam 41-3 in the horizontal azimuth psi3 and the levels of the nearby subordinate horizontal phase matching beams 41-1, 41-2, 42-4, and 41-5 are found by residual level calculators 70a - 70e, so that the differences (residual level) are outputted as depression/elevation azimuths to the signal source 43. Consequently, even if a high-level noise is present in a depression/elevation azimuth where the signal source 43 is not present, the influence of the noise can be removed on condition that the noise has a nearly equal level almost in the noise azimuth, and consequently the depression/elevation azimuth of the target signal source 43 can accurately be estimated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a method for estimating the angle of elevation, which is used to measure the angle of arrival of a signal received by a surface array from a signal source existing in water or the like. It is related to.

(Prior Art) Conventionally, as a method for estimating the arrival elevation angle of a signal from a signal source, a surface array in which a plurality of sensors are arranged in a planar manner receives a signal from a signal source, and calculates the angle of arrival of a signal from a signal source. The elevation angle was determined by comparing the absolute levels of the elevation phase outputs. An example is shown in FIG.

FIG. 2 is a block diagram showing a configuration example of an elevation angle estimating device for explaining a conventional elevation angle estimation method using a surface array.

This elevation angle estimating device targets broadband signals and uses a 4 stave (horizontal) x 5 stack (vertical) surface array 10.
This is a device that estimates the elevation angle when phasing 5 beams in the elevation direction.

The structure of the surface array 10 is shown in FIG.
A plurality of sensors are arranged in a planar shape, and are comprised of four sensor array sections 10a to 10d.

Elevation phasing devices 20a to 20d for phasing the elevation angle are connected to each of the sensor array sections 10a to 10d, and horizontal phasing devices 21a to 21a for phasing in the horizontal direction are connected to the output side thereof. 21e are connected to each other. moreover,
Each of the horizontal phasers 21a to 21e includes square processors 22a to 22e.
A peak detector 23 is connected via 22e, and an output terminal 24 is connected to the output side of the peak detector 23.

Next, a method for estimating the elevation angle of a signal source using this elevation angle estimating device will be described.

For example, a signal from a signal source in seawater is received by the area array 10. The signal input to the surface array 10 at time t is converted into an electric signal for each stave 1 to 4, and then
The signal is input to the first to fourth waveform phasers 20a to 20d.

The first elevation phaser 20a uses five stacked signals from the sensor array section 10a in the surface array 10 to determine the arrival of upper and lower elevation angles with respect to five elevation directions (elevation directions). Performs time adjustment, or phasing. The first heave phasing device 20a has a first heave phasing direction (heave phasing direction>θ).
1 output xll(t) is sent to the horizontal phasing device 21a, and the output x12(1) of the second phase phasing direction θ2 is sent to the horizontal phasing device 21b.
Then, the output x13 (t) of the third vertical phasing direction θ3 is sent to the horizontal phasing device 21c, and the output x1 of the fourth vertical phasing direction θ4 is sent to the horizontal phaser 21c.
4 (t) to the horizontal phasing device 21d, and the output x15 (t) of the fifth phase phasing direction θ5 to the horizontal phasing device 21e.
Output each. Similarly, the second to fourth phaser 2
0b to 20d also have their outputs X21(t) to x25(t)
, . . . The outputs of x41 (t) to x45 (t) are output to each horizontal phaser 21a to 21e, respectively.

The horizontal phaser 21a includes the first to fourth tilt phaser 20a to
Using the outputs xi 1 (t) to x41 (t) of 20d, horizontal arrival time adjustment, that is, horizontal phasing, is performed with respect to the azimuth (direction) where the signal source to be estimated exists, and the phasing output yl (t) is output to the square processor 22a.

Similarly, the horizontal phasers 21b to 21e also perform horizontal phasing in the same direction, and output the phased outputs y2 (t) to y5 (t) to the square processors 22b to 22e, respectively.

The squaring processor 22a performs squaring processing on the phased output yl(t) from the horizontal phasing device 21a, and as a result, y12
(t> is output to the peak detector 23.Similarly, the square processors 22b to 22e also output a phased output y2 (t> to y5
(After squaring each t>, the result is y22
(t) to y5'' (t) is output to the peak detector 23.

The peak detector 23 uses the outputs y12 (t) to y52 (t) of the square processors 22a to 22e to generate a vertical beam for a measurement range in a predetermined vertical direction in order to simplify the structure. If the number is small, the peak level is detected after processing such as interpolation, and the elevation azimuth eak at which the peak value is obtained is outputted to the output terminal 24 as the estimated elevation angle of the signal source eak.

(Problems to be Solved by the Invention) However, the above-mentioned elevation angle estimation method has the following problems.

FIGS. 4(a) and 4(b) are diagrams illustrating problems of the prior art.

As shown in FIG. 4(a), consider the case where the surface array 10 is configured using, for example, a hydrophone which is an acoustic/electrical converter, and the elevation angle of a signal source 31 in the sea is estimated.

The surface array 10 is submerged in the sea, and the surface array 1° forms the first to fifth vertical beams 11-1 to 11-5,
When estimating the elevation angle of the signal source 31, when the noise level at the sea surface 30 is high due to the influence of waves, etc., as shown in FIG. The level of sea surface noise 3°a increases. Therefore, the peak detector 23 cannot detect the elevation angle θS of the signal source 31 by eak with the estimated elevation angle θ of the signal source 31, and the sea surface noise 3
There was a problem in selecting an elevation angle θN of 0a. Furthermore, depending on the state of the sea surface noise 30a, the level of the signal source 31 may be masked (shielded) by the sea surface noise 30a, making it impossible to detect local peaks caused by the signal source 31, as shown in FIG. 4(b). There are also cases.

The present invention solves the problems that the prior art had, such as sea surface noise, which is relatively isotropic in the horizontal plane (non-directional, coming from any direction). The purpose of the present invention is to provide a method for estimating an elevation angle that solves the problem that the detection level of a signal source is masked by noise (noise caused by noise), making it impossible to estimate an elevation angle with high accuracy.

(Means for Solving the Problems) In order to solve the above problems, the present invention uses a planar array in which a plurality of sensors are arranged in a planar manner, and uses a surface array having a plurality of elevation angles for a signal from a signal source. In the elevation angle estimating method of forming a phased beam and estimating the arrival angle of the signal from the phased output level of the phased beam, the following measures are taken.

In other words, a signal source has a level only in the horizontal direction (horizontal direction) where the signal source exists, whereas noise has approximately the same level in horizontal directions nearby. Focusing on each elevation angle, a main horizontally phased beam is formed in the direction of arrival of the signal in the horizontal direction, and a plurality of sub horizontally phased beams are formed in the vicinity thereof, and the phasing of the main horizontally phased beam is performed. A surplus level is obtained by subtracting the phased output level of the sub-horizontal phased beam from the output level, and the arrival elevation angle of the signal is estimated from the peak of the temporality of the surplus level. .

(Function) According to the present invention, since the elevation angle estimation method is configured as described above, when performing elevation angle phasing and horizontal phasing for a signal from a signal source, Multiple horizontal phasing is also performed in the vicinity of the horizontal direction, and the difference between the level of the horizontal direction where the signal source is present and the level in the vicinity, that is, the surplus level, is obtained, and from the peak of the temporality of the surplus level. , estimate the arrival elevation angle of the signal source. As a result, even if there is a high level of noise in the vertical direction where there is no signal source,
The influence of that noise is removed, and the elevation angle of the target signal source can be estimated with high accuracy. Therefore, the above problem can be solved.

(Embodiment) FIG. 1 is a block diagram of a configuration of an elevation angle estimating device for explaining an elevation angle estimation method showing an embodiment of the present invention.

This elevation angle estimating device uses, for example, a 4 stave x 5 stack surface array 40 similar to the conventional one, and estimates the elevation angle when phasing 5 beams in the lateral direction and 5 beams in the horizontal direction. It is.

The surface array 40 is formed by arranging a plurality of sensors (for example, hydrophones) in a surface shape, and is composed of four sensor array sections 40a to 40d. Each of the sensor array sections 40a to 40d includes first to fourth phase shifters 5.
0a to 50d are connected to each other. Each of the vertical phasing devices 50a to 50d performs vertical phasing in the vertical direction using each of the five stack signals from each of the sensor array sections 40a to 40d, and performs vertical phasing in the vertical direction. Outputs of phase directions θ1 to θ5 xllllt) to x15 (t), x21 (t) to x2
5 (t), x31 (t) to x35 (t).

x41 (t) ~ x45 (t), x51 (t)
This circuit supplies ~x55 (t) to the horizontal phasers 61a to 61d, respectively, and is composed of a delay circuit, an adder, and the like.

The horizontal phasing devices 61a to 61d are the horizontal phasing devices 50a to 50.
Perform horizontal phasing of each of the 5 beams using the output of d,
Each phased output yll (t) ~ y15 (t), , Y2
1 (t) ~ y25 (t), y31 (t) ~ y35
(t), y41 (t) ~ y45 (t), y51 (t
) to y55 (t) to the two-bundle processors 62a to 62e, respectively, and is comprised of a delay circuit, an adder, and the like. The two-bundle processors 62a to 62e are connected to a peak detector 80 via respective surplus level calculators 70a to 70e, and the peak detector 80 is connected to an output terminal 81.

Each of the square processors 62a to 62e includes each horizontal phaser 61a to 62e.
This is a circuit that squares the output of 61d and supplies the results to each of the surplus level calculators 70a to 70e, and is composed of multipliers and the like. Each surplus level calculator 70a-7
0e is the output yl12 (
t) ~ y152 (t), y212 (t) ~ y252
(t>, y312 (t) ~ y352 (t), y41
2 (t) ~, y452 (t), y512 (t) ~
This is a circuit that inputs y552 (t), calculates each surplus level, and provides the calculation results Z12 (t> to z52 (t>) to the peak detector 80.Peak detector 80
is the output z12(1) of the surplus level calculators 70a to 70e.
) to z52 (t), and outputs the elevation direction θ from the peak of the temporality to the output terminal 81 as the estimated value of the elevation angle of the signal source, and is composed of a comparator and the like. There is.

5(a>, (b) are diagrams for explaining the surface array 40 in FIG. 1, where (a> is a plan view and FIG. 5(b)
is a side view.

As shown in FIG. 5(a), the surface array 40 includes a signal source 4
3, one main horizontal phased beam 41-
3 and four sub-horizontal phased beams 41-1.4 on its left and right
1-2.41-4.41-5. Further, as shown in FIG. 4(b), this surface array 40 has a function of forming five phased beams 42-1 to 42-5 in the vertical direction with respect to the signal source 43. ing.

FIG. 6 is a circuit diagram of the surplus level calculator 70a in FIG. 1.

This surplus level calculator 70a calculates yl12 out of the outputs yl12 (t) to y152 (t) of the square processor 62a.
(t>, y122 (t), y142 (t), y1
52 (t), and a subtractor 72 that subtracts the average level y12 (t) from the output y132 (t). The other surplus level calculators 70b to 70e also have the same circuit configuration.

Next, a method for estimating the elevation angle using the elevation angle estimation device configured as described above will be described.

As shown in FIG. 5, a signal from a signal source 43 is received by a surface array 40. As shown in FIG. The signal input to the surface array 40 at time t is transmitted to the sense array section 40a of the surface array 40.
~40d is converted into an electric signal and input to the first to fourth swing phasers 50a to 50d for each stave 1 to 4 unit.

The first swing phaser 50a uses five stacked signals from the sense array section 40a of the surface array 40, and uses the five stacked signals as shown in FIG.
The vertical phasing is performed on the vertical directions of the vertical phased beams 42-1 to 42- shown in b).

In this vertical phaser 50a, the output xll(t) of the first vertical phase phasing direction θ1 is sent to the horizontal phaser 61a, and the output x12 (t) of the second vertical phase phasing direction θ2 is sent to the horizontal phaser 61a. Similarly, the outputs x of the third to fifth positive phase directions θ3 to θ5 are sent to the phase shifter 61b.
13 (t) to x15 (t) to the horizontal phaser 61c to 6
1e, respectively. Similarly, other phasing phasing devices 5
0b to 50d also perform vertical phasing of 5 beams, and the phasing direction outputs X21 (t) to x25 (t), x'31
(t) ~x35 (t), x41 (t) ~x45
(t) is applied to horizontal phasers 61a to 61e, respectively.

The horizontal phaser 61a includes the first to fourth tilt phaser 50a to
Using the output xll (t) ~ x41 (t) of 50d,
With respect to the first vertical direction θ1, as shown in FIG. 5(a), the azimuth (direction) ψ3 where the signal source 43 to be estimated exists
Centering on the main horizontal phased beam 41-3, two sub-horizontal phased beams 41-1.41-2.41 are placed on the left and right in the horizontal direction.
-4.41-5, total of 5 horizontal phased beams 41-1 to 4
Horizontal phasing of 1-5 (ψ1. ψ2. 3.
) to the square processor 62a. Similarly, other horizontal phasers 61b for the second to fifth vertical directions θ2 to θ5
~61e also performs horizontal phasing of 5 beams in the same direction, and the results are used as phased outputs y21 (1) ~ y25 (t), y31
(t) ~ y35 (t),, y41 (t) ~ y45
(t) and y51(1) to y55(t) to the other two bundle processors 62b to 62e, respectively.

The square processors 62a to 62e are horizontal phasers 61a to 61
After squaring the outputs of e, the result is V11
2 (t) ~ y152 (t), y212 (t) ~ y
252 (t), y312 (t) ~ y35' (t
), y412 (t) to y452 (t).

y51'' (t) to y552 (t) are output to the surplus level pressure calculators 70a to 70e, respectively.

As shown in FIG. 6, in the surplus level calculation circuit 0a for the first vertical azimuth θ1, horizontal phasing azimuths ψ1, . ψ2. ψ4
．． Square processing output of ψ5 y112 (t), y122 (
t),,y142 (t).

y152 (t) is input to the average processor 71.

The average processor 71 outputs a squared processing output yl12 (t).

y122 (t), y14" (t), y152 (
t) and outputs the calculation result to the subtracter 72. The subtracter 72 outputs the output y132 (t) of the third horizontal phasing direction ψ3 which is the signal source direction.
Subtract the average level y12 (t) from , and the result is z
12 (t) to the peak detector 80 of FIG.

Similarly, the surplus level calculators 70b to 70e for the second to fifth vertical directions θ2 to θ5 also perform the same processing as described above.

The peak detector 80 in FIG. 1 is a surplus level calculator 70a.
Using the output z12 (t) ~ Z52 (1) of ~70e,
Phased beams 42-1 to 42-5 shown in FIG. 5(b)
When the number of elevation beams is small for a given measurement range in the elevation direction, the peak level is detected after processing such as interpolation to improve accuracy, and the peak value is taken. The elevational direction θ is outputted to the output terminal 81 as the estimated elevation angle eak of the signal source 43.

As described above, this embodiment has the following advantages.

In this embodiment, as shown in FIG. 5(a), the signal source 43
There is also a sub-horizontal phased beam 4 near the horizontal direction ψ3 where
1-1.41-2.41-4.41-5 to perform multiple horizontal phasing, and adjust the level of the main horizontal phasing beam 41-3 in the horizontal direction ψ3 and the level of the splint in the vicinity The difference with the level of the phase beam 41-1゜41-2.41-4.41-5 is calculated by the surplus level calculators 70a to 70e, and the difference (surplus level) is outputted in the vertical direction to the signal source 43. Toshina. Therefore, even if there is a high level of noise in the vertical direction where the signal source 43 does not exist, if the noise has a similar level in the vicinity of the noise direction (i.e., other noise such as sea surface noise) If the noise is relatively isotropic in the horizontal plane and comes from the vertical direction of be able to.

FIG. 7 is another block diagram of the surplus level calculator 70a in the elevation angle estimating device shown in FIG.

This surplus level calculator 70a includes an average processor 73-1, 73-2 that calculates the average value of the square processor 62a, and a comparator 74 that compares the outputs of the average processors 7B-1 and 73-2.
and a subtracter 75 that subtracts the output of the comparator 74 from the output of the square processor 62a. The other surplus level calculators 70b to 70e also have the same circuit configuration.

In this surplus level calculator 70a, as shown in FIG. The two-bundle processing outputs yll'' (t) and y122 (t) in the phased beam 41-1.41-2 are input to the averaging processor 73-1.
．． The two-bundle processing outputs y142 (t) and y152 (t) in the sub-horizontal phased beam 41-4.41-5 of ψ5 are as follows.
It is input to the average processor 73-2. Each average processor 731
．． 73-2 is an azimuth ψ1. to the left of the horizontal azimuth ψ3 of the signal source 43. The average level of ψ3 and the right direction ψ4. The average level of ψ5 is determined, and the results are output to the comparator 74.

The comparator 74 compares the levels of the outputs of the average processors 73 - 1 and 73 - 2 and outputs the one with the lower level to the subtracter 75 . In the subtracter 75, the comparator 74
The output of z12 (t) is subtracted and the result z12 (t) is output to the peak detector 8o in FIG. Other surplus level calculator 70
b to 70e also perform similar operations.

When such surplus level calculators 70a to 70e are used, as compared to FIG. 6, as shown in FIG.
Even if there is a second signal source, since the comparator 74 selects the direction with the lower signal, the influence of the second signal source can be accurately removed.

Note that the present invention is not limited to the illustrated embodiment, and various modifications are possible. Examples of such modifications include the following.

(i> In FIG. 1, the phase shifters 50a to 50d
Even if the order of the horizontal phasing devices 61a to 61e is changed, and horizontal phasing is performed on the signal source 43, then tilt phasing is performed, substantially the same advantages as in the above embodiment can be obtained.

(ii) In the above embodiment, the target is a wideband signal, but the present invention can also be applied to a narrowband signal.

In this case, if frequency division is performed by Fast Fourier Transform (FFT) or the like, and a frequency bin (frequency division unit by FFT) that includes the narrow band frequency of the signal source 43 whose elevation angle is to be estimated is selected, Accurate elevation angle estimation is also performed for the narrowband signal from the signal source 43.

(iii) In the above embodiment, the elevation angle was estimated by phasing 5 beams in the vertical direction and 5 beams in the horizontal direction using a 4 stave x 5 stack surface array 40. It is also possible to perform phasing using another number of beams using a surface array. In addition, when the signal source 43 is underwater, the surface array 40 may be configured with an acoustic/electrical transducer, but when the signal source 43 is in the air, it can be configured by converting radio waves, ultrasonic waves, etc. into electricity. If it is configured to convert into a signal, it is also possible to estimate the elevation angle with respect to the signal source 43.

(Effects of the Invention) As described above in detail, according to the present invention, a plurality of horizontal phasing operations are performed also in the vicinity of the signal source in the horizontal direction,
The phasing output level in the vicinity is subtracted from the main phasing output level in the horizontal direction to obtain a surplus level, and the arrival angle of the signal is estimated from the surplus level. Therefore, even if there is a high level of noise in the direction where the signal source does not exist, if the noise has the same level in the vicinity of the noise direction, the effect of that noise can be removed. As a result, the elevation angle of the target signal source can be estimated with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a configuration of a elevation angle estimating device showing an embodiment of the present invention, FIG. 2 is a block diagram of a conventional elevation angle estimation device, and FIG. 3 is a structural diagram of a surface array in FIG. 2. Figure 4 (
a>, (b) are diagrams explaining the problems of the prior art, FIG. 5 (a>, (b) are diagrams explaining the surface array in FIG. Circuit diagram of level calculator, 7th
This figure is another circuit configuration diagram of the surplus level calculator in FIG. 1. 40... surface array, 41-1.41-2.41
-4.41-5...Sub-horizontal phased beam, 41-
3. Main horizontal phased beam, 42-1 to 42-5
・・・・・・Full phased beam, 50a to 50d...
. . . Horizontal phasing device, 62a to 62e . . . Square processor, 70a to 61e.
70e... Surplus level calculator, 71.73-1
．． 73-2... Average processor, 72.75...
...Subtractor, 74...Comparator, 80...
...Peak detector.

Claims (1)

[Claims] A planar array in which a plurality of sensors are arranged in a planar manner is used to form a phased beam with a plurality of angles of elevation in response to a signal from a signal source, and the phased beam of the phased beam is In the elevation angle estimating method of estimating the arrival angle of the signal from the phased output level, for each elevation angle, a main horizontal phased beam is formed horizontally in the direction of arrival of the signal, and a plurality of beams are formed in the vicinity thereof. forming a sub-horizontal phased beam, subtracting the phased output level of the sub-horizontal phased beam from the phased output level of the main horizontally-phased beam to obtain a surplus level; A method for estimating an elevation angle, comprising estimating an arrival elevation angle of the signal from a peak.