WO2016039043A1 - Target detection device, radar device, and target detection method - Google Patents

Abstract

[Problem] To provide a target detection device that accurately suppresses interference and a radar device provided with the same. [Solution] A signal processing unit 15 generates target data for which the influence of interference is suppressed on the basis of detected data and interpolated data. The signal processing unit 15 is provided with an interference detection unit 19, an interpolated data generation unit 21, and a target data generation unit 24. From the detected data, the interference detection unit 19 detects a position at which there is interference. The interpolated data generation unit 21 generates interpolated data on the basis of the detected data before the occurrence of interference at the position where interference was detected. The target data generation unit 24 generates target data by substituting the detected data at the position where interference was detected with the interpolated data.

Description

Target detection apparatus, radar apparatus, and target detection method

The present invention relates to a target detection apparatus that suppresses the influence of interference and a radar apparatus including the target detection apparatus.

The radar device detects the presence or absence of a target by emitting a transmission signal and receiving an echo signal reflected from the target. However, the signal received by the radar apparatus includes an artificial interference wave in addition to the echo signal. A target detection device used in a radar device suppresses the influence of interference waves. As a method for suppressing interference, for example, there is a method shown in FIG.

FIG. 9A is a diagram illustrating a method of suppressing interference by selecting the minimum value. Here, the detection data a, i, b represent the amplitude of the echo signal reflected from the target. The targets related to the detection data a, i, b are arranged in this order in the azimuth direction. The detection data a and b have a relationship of a <b. The detection data i is affected by interference. In the method of selecting the minimum value, the detection data i is replaced with the detection data a. That is, the detection data affected by the interference is replaced with the minimum detection data of the surrounding detection data.

FIG. 9B is a diagram showing a method of suppressing interference by linear interpolation (see Patent Document 1). The detection data c, i ₁ , i ₂ , i ₃ , d represent the amplitude of the echo signal reflected from the target. The targets related to the detection data c, i ₁ , i ₂ , i ₃ , d are arranged in this order in the azimuth direction. The detection data i ₁ , i ₂ , i ₃ are affected by interference. In the linear interpolation method, Δ x (d−c) / 4 is replaced with i _x = c + Δx (x = 1, 2, 3).

JP 2011-191141 A

However, in the method of selecting the minimum value, there is a risk of removing parts other than interference. Further, since the data arrangement is changed, the phase information of the echo signal cannot be used in the subsequent signal processing. In the method of performing linear interpolation, interference cannot be suppressed with sufficient accuracy so as not to adversely affect subsequent processing.

An object of the present invention is to provide a target detection apparatus that accurately suppresses interference and a radar apparatus including the target detection apparatus.

The target detection apparatus of the present invention generates target data in which the influence of interference is suppressed based on detection data and interpolation data. The target detection apparatus of the present invention includes an interference detection unit, an interpolation data generation unit, and a target data generation unit. The interference detection unit detects the position where the interference occurs from the detection data. The interpolation data generation unit generates interpolation data based on detection data before occurrence of interference at a position where interference is detected. The target data generation unit generates target data by replacing the detection data at the position where the interference is detected with the interpolation data.

In this configuration, interpolation data is generated based on target information before the occurrence of interference. For this reason, highly accurate interpolation data can be obtained. Then, by replacing the detection data in which the interference has occurred with the interpolation data, the interference of the detection data can be suppressed with high accuracy.

Moreover, in the target detection apparatus of the present invention, the interpolation data generation unit has a data replacement unit and a filter. The data replacement unit generates the first intermediate data by replacing the detection data at the position where the interference is detected with the detection data before the occurrence of the interference. The filter outputs the second intermediate data by suppressing the high frequency component of the first intermediate data. The target data generation unit uses the second intermediate data at the position where the interference is detected as interpolation data.

This configuration shows a specific example of the interpolation data generation unit.

Also, in the target detection apparatus of the present invention, the detection data is arranged in the distance direction and the azimuth direction. First intermediate data in a region where the distance is constant is input to the filter.

In this configuration, the first intermediate data is arranged in the azimuth direction. On the other hand, the position where interference is detected extends in the distance direction and does not extend in the azimuth direction. For this reason, the high frequency component of the first intermediate data can be suppressed by passing the first intermediate data through the filter.

Moreover, in the target detection device of the present invention, the filter is a low-pass filter.

The radar apparatus of the present invention includes a transmission unit, a reception unit, and a target detection apparatus of the present invention. The transmission unit transmits a detection signal. The receiving unit receives an echo signal corresponding to the detection signal and generates detection data.

Also, the target detection method of the present invention generates target data in which the influence of interference is suppressed based on detection data and interpolation data. The target detection method of the present invention includes the following steps. The position where the interference occurs is detected from the detection data. Interpolation data is generated based on detection data before the occurrence of interference at a position where the interference is detected. The target data is generated by replacing the detection data at the position where the interference is detected with the interpolation data.

According to the present invention, it is possible to realize a target detection apparatus that accurately suppresses interference and a radar apparatus including the target detection apparatus.

FIG. 1A is a block diagram showing a radar apparatus according to the first embodiment. FIG. 1B is a block diagram illustrating the target detection apparatus according to the first embodiment. FIG. 2A shows the data structure of the detection data _Xn . FIG. 2B is a diagram illustrating each area of the detection data _Xn . It is a figure which shows the process of suppressing interference. It is a flowchart which shows the acquisition flow of detection data X _{nm, k} . It is a flowchart which shows an interference suppression flow. FIG. 6A shows the absolute value of the detection data _Xn . FIG. 6B is a diagram showing the absolute value of the detection data _Xn subjected to signal processing only by the matched filter. FIG. 6C is a diagram illustrating the absolute value of the detection data _Xn subjected to signal processing by the interference interpolation unit 20 and the matched filter. FIG. 7A shows the phase of the detection data _Xn . FIG. 7B is a diagram showing the phase of the detection data _Xn subjected to signal processing only by the matched filter. FIG. 7C is a diagram showing the phase of the detection data _Xn signal-processed by the interference interpolation unit 20 and the matched filter. FIG. 8A shows the absolute value of the detection data _Xn . FIG. 8B is a diagram illustrating the absolute value of the detection data _{Xn in} which only land removal processing has been performed. FIG. 8C is a diagram illustrating the absolute value of the detection data X _n that has been subjected to signal processing by the interference interpolation unit 20 and then subjected to land removal processing. FIG. 9A is a diagram illustrating a method of suppressing interference by selecting the minimum value. FIG. 9B is a diagram illustrating a method for suppressing interference by linear interpolation.

A target detection apparatus and a radar apparatus including the target detection apparatus according to the first embodiment of the present invention will be described. FIG. 1A is a block diagram showing the radar apparatus 10. The radar apparatus 10 includes an antenna 11, a transmission / reception switching unit 12, a transmission unit 13, a reception unit 14, a signal processing unit 15, and a display unit 16. The signal processing unit 15 corresponds to the target detection device of the present invention.

The detection signal output from the transmission unit 13 passes through the transmission / reception switching unit 12 and is radiated from the antenna 11. The detection signal hits the target and is re-radiated as an echo signal. The echo signal is received by the antenna 11, passes through the transmission / reception switching unit 12, and is input to the reception unit 14. The echo signal is converted into detection data by the receiving unit 14. The detection data is signal-processed by the signal processing unit 15 and displayed on the display unit 16 in a predetermined format. These steps are repeated while rotating the antenna 11 at a predetermined rotational speed. Thereby, the radar apparatus 10 detects the presence or absence of a target around the antenna.

FIG. 1B is a block diagram showing the signal processing unit 15 (target detection device). The signal processing unit 15 includes a storage unit 18, an interference detection unit 19, an interference interpolation unit 20, and a filter processing unit 25. The interference interpolation unit 20 includes an interpolation data generation unit 21 and a target data generation unit 24. The interpolation data generation unit 21 includes a data replacement unit 22 and a low-pass filter 23.

と表される。ここで、ｎ，ｉ，ｊ，Ｎ_ｄ，Ｎ_ｓは整数である。ｘ_ｎ（ｉ，ｊ）は複素数である。ｘ_ｎ（ｉ，ｊ）の絶対値はエコー信号の振幅に相当し、ｘ_ｎ（ｉ，ｊ）の位相はエコー信号の位相に相当する。このエコー信号は、距離ｉΔｒ、方位角ｊΔθに位置する物標により反射されている。ΔθおよびΔｒはスケールファクタである。ただし、ｘ_ｎ（ｉ，ｊ）の値は、干渉、雑音、マルチパス等の影響を受けている。 The storage unit 18 stores detection data { _Xn , _Xn-1 , _Xn-2 , ...}. The detection data _Xn is the nth detection data. FIG. 2A shows the data structure of the detection data _Xn . FIG. 2B is a diagram illustrating each area of the detection data _Xn . The detection data _Xn is

It is expressed. Here, n, i, j, N _d , and N _s are integers. x _n (i, j) is a complex number. The absolute value of x _n (i, j) corresponds to the amplitude of the echo signal, and the phase of x _n (i, j) corresponds to the phase of the echo signal. This echo signal is reflected by a target located at a distance iΔr and an azimuth angle jΔθ. Δθ and Δr are scale factors. However, the value of x _n (i, j) is affected by interference, noise, multipath, and the like.

と表される。等距離データＳ_ｎ，ｋは、距離ｋΔｒに位置する物標の存否を示す。また、探知データＸ_ｎで干渉が発生している領域を領域Ｄ_ｎとして、干渉データＩ_ｎは、

と表される。干渉データＩ_ｎは、干渉が発生している探知データである。また、等距離データＳ_ｎ，ｋに含まれる干渉データＩ_ｎ，ｋは、

と表される。 The equidistant data Sn _{, k} is

It is expressed. The equidistant data Sn _{, k} indicates the presence / absence of a target located at the distance kΔr. Further, an area where interference is occurring at the detection data X _n as region D _n, the interference data I _n is

It is expressed. Interference data I _n is the detection data interference occurs. Also, the interference data _{I n} contained equidistant data _{S n,} the _{k, k} is

It is expressed.

The interference detection unit 19 detects the area D _n where the interference has occurred from the detection data X _n . Then, the interference detection unit 19 outputs information on the region D _{n to} the data replacement unit 22 and the target data generation unit 24. Detection methods for regions D _n, rule-based, amplitude deviation comparison method, STFT method or the like is used.

Data replacing unit 22 obtains equidistant data _{S n, k, S n-} m, the _k, and generates an intermediate data _{V n, k.} The equidistant data S _{nm, k} corresponds to “detection data before occurrence of interference” of the present invention. The intermediate data V _{n, k} corresponds to the first intermediate data of the present invention.

As shown in FIG. 3A, the data replacement unit 22 acquires equidistant data Sn _{, k} from the detection data _Xn . In addition, the data replacement unit 22 acquires equidistant data S _{nm, k} from the detection data X _nm . FIG. 3A is a diagram showing equidistant data S _{n, k} , S _{nm, k} .

The detection data X _{nm, k} is acquired as shown in FIG. FIG. 4 is a flowchart showing an acquisition flow of the detection data X _{nm, k} . First, m = 1 is set (S201). If the region D _{nm, k} is the empty set φ (S202), equidistant data S _{nm, k} is acquired (S204). If the region D _{nm, k} is not the empty set φ (S202), m is set to m + 1 and the process returns to step S202 (S203). Note that if the region D _{n, k} and the region D _{nm, k} do not overlap, the equidistant data S _{nm, k} may be acquired.

と表される。 The intermediate data V _{n, k} is generated by replacing the interference data I _{n, k} with the equidistant data S _{nm , k} of the region D _{n, k} as shown in FIG. FIG. 3B is a diagram showing a process of generating intermediate data V _{n, k} . The intermediate data V _{n, k} is

It is expressed.

と表される。ここで、ｗ_ｎ（ｉ，ｊ）はローパスフィルタ２３の出力である。 As shown in FIG. 3C, the low-pass filter 23 suppresses high-frequency components of the intermediate data V _{n, k ,} thereby outputting intermediate data W _{n, k in} which the data value changes smoothly. FIG. 3C is a diagram illustrating a process of generating intermediate data W _{n, k} . The intermediate data W _{n, k} corresponds to the second intermediate data of the present invention. The intermediate data W _{n, k} is

It is expressed. Here, w _n (i, j) is an output of the low-pass filter 23.

Interference data I _n extends elongated in the distance direction, does not extend in the azimuthal direction. Therefore, by passing the intermediate data V _{n, k} continuous in the azimuth direction through the low-pass filter 23, the high frequency component of the intermediate data V _{n, k} can be suppressed.

と表される。物標データＹ_ｎ，ｋは、

と表される。 The target data generation unit 24 generates target data Y _{n, k} by replacing the interference data I _{n, k} with the interpolation data P _{n, k as shown} in FIG. FIG. 3D is a diagram illustrating a process of generating target data Y _{n, k} . Interpolated data P _{n, k} is intermediate data W _{n, k} of region D _{n, k} ,

It is expressed. The target data Y _{n, k} is

It is expressed.

The filter processing unit 25 applies a matched filter (MatchedFilter) or the like to the target data Y _{n, k} to remove noise, clutter, and the like.

By performing the above signal processing on the equidistant data S _{n, k} (k = 1,..., N _d ), interference generated in the detection data X _n can be suppressed.

Next, a process for suppressing interference will be described. FIG. 5 is a flowchart showing an interference suppression flow. First, equidistant data S _{n, k} , S _{nm, k} are extracted (S101). Region _{D n,} equidistant data _{S n-m} of _{k, k} the interference data _{I n,} by replacing _k, to generate the intermediate data _{V n, k} (S102). The intermediate data W _{n, k} is generated by passing the intermediate data V _{n, k} through the low-pass filter 23 (S103). The intermediate data W _{n, k} of the region D _{n, k} is set as interpolation data P _{n, k} . The target data Y _{n, k} is generated by replacing the interference data I _{n, k} with the interpolation data P _{n, k} (S104).

FIG. 6A shows the absolute value of the detection data _Xn . FIG. 6B is a diagram showing the absolute value of the detection data _Xn subjected to signal processing only by the matched filter. FIG. 6C is a diagram illustrating the absolute value of the detection data _Xn subjected to signal processing by the interference interpolation unit 20 and the matched filter. Here, the area | region where an absolute value is more than a fixed value is displayed.

When no signal processing is performed, a straight line extending in the distance direction appears due to the influence of interference. When signal processing is performed using only the matched filter, a part of the target is not displayed because the target is removed together with the interference. On the other hand, when the signal processing is performed by the interference interpolation unit 20 and the matched filter, only the interference is suppressed, so that the target is accurately displayed.

FIG. 7A shows the phase of the detection data _Xn . FIG. 7B is a diagram showing the phase of the detection data _Xn subjected to signal processing only by the matched filter. FIG. 7C is a diagram showing the phase of the detection data _Xn signal-processed by the interference interpolation unit 20 and the matched filter. Here, a region where the phase is a value within a certain range is displayed.

When signal processing is not performed, a straight line extending in the distance direction appears due to the influence of interference, as in FIG. When the signal processing is performed by the interference interpolation unit 20 and the matched filter, the phase change is smooth because the interference is suppressed with higher accuracy than when the signal processing is performed only by the matched filter.

FIG. 8A shows the absolute value of the detection data _Xn . FIG. 8B is a diagram illustrating the absolute value of the detection data _{Xn in} which only land removal processing has been performed. FIG. 8C is a diagram illustrating the absolute value of the detection data X _n that has been subjected to signal processing by the interference interpolation unit 20 and then subjected to land removal processing. Here, as in FIG. 6, a region whose absolute value is equal to or greater than a certain value is displayed.

In the land removal, the low frequency component of the detection data _Xn is suppressed. When only land removal processing is performed, the land is not sufficiently removed due to phase variations. On the other hand, when the land removal process is performed after the signal processing by the interference interpolation unit 20, the phase change is smooth, and thus the land is removed with high accuracy.

According to the first embodiment, the interpolation data P _{n, k} is generated based on the equidistant data S _{nm, k} before the occurrence of interference. That is, the interpolation data P _{n, k} is generated based on the target information before the occurrence of interference. For this reason, it is possible to obtain interpolation data P _{n, k} with high accuracy. Then, by replacing the interference data I _{n, k} with the interpolation data P _{n, k} , interference of the detection data X _n can be suppressed with high accuracy.

Further, not only the absolute value of the detection data _Xn but also the phase is suppressed based on the target information before the occurrence of interference. Thereby, interference can be suppressed without losing the amplitude information and phase information of the echo signal. For this reason, the amplitude information and phase information of the echo signal can be used in subsequent signal processing.

DESCRIPTION OF SYMBOLS 10 ... Radar apparatus 11 ... Antenna 12 ... Transmission / reception switching part 13 ... Transmission part 14 ... Reception part 15 ... Signal processing part 16 ... Display part 18 ... Memory | storage part 19 ... Interference detection part 20 ... Interference interpolation part 21 ... Interpolation data generation part 22 ... Data replacement unit 23 ... Low-pass filter 24 ... Target data generation unit 25 ... Filter processing unit

Claims (6)

A target detection apparatus that generates target data in which the influence of interference is suppressed based on detection data and interpolation data,
An interference detection unit for detecting a position where the interference occurs from the detection data;
An interpolation data generating unit that generates the interpolation data based on detection data before the occurrence of interference at a position where the interference is detected;
A target detection apparatus comprising: a target data generation unit that generates the target data by replacing the detection data at the position where the interference is detected with the interpolation data. The target detection apparatus according to claim 1,
The interpolation data generation unit has a data replacement unit and a filter,
The data replacement unit generates first intermediate data by replacing the detection data at the position where the interference is detected with the detection data before the occurrence of the interference,
The filter outputs second intermediate data by suppressing high frequency components of the first intermediate data,
The target data generation unit, wherein the second intermediate data at the position where the interference is detected is the interpolation data. The target detection device according to claim 2,
The detection data is arranged in the distance direction and the azimuth direction,
The target detection apparatus, wherein the first intermediate data of a region having a constant distance is input to the filter. The target detection apparatus according to claim 2 or 3,
The target detection apparatus, wherein the filter is a low-pass filter. A transmission unit for transmitting a detection signal;
A receiver that receives an echo signal for the detection signal and generates the detection data;
A radar apparatus comprising: the target detection apparatus according to claim 1. A target detection method for generating target data in which influence of interference is suppressed based on detection data and interpolation data,
Detecting the position where the interference occurs from the detection data;
Generating the interpolation data based on detection data before occurrence of interference at a position where the interference is detected;
A target detection method comprising: generating the target data by replacing the detection data at a position where the interference is detected with the interpolation data.

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