JP4484736B2 - Azimuth detection receiver, target detection system, and signal processing method - Google Patents

Description

  The present invention relates to an azimuth detection receiving apparatus, a target detection system, and a signal processing method. More specifically, the present invention relates to azimuth detection reception that extracts a communication wave by frequency hopping that has arrived from a detection target from a received signal and identifies the direction of the detection target. It relates to the improvement of the apparatus.

In recent years, there has been proposed a receiving apparatus that receives a communication wave (hereinafter referred to as an FH wave) by frequency hopping (FH wave) that switches the frequency of a carrier wave at a short time interval and identifies the direction of a detection target as a source of the communication wave. (For example, Patent Document 1). The receiving apparatus described in Patent Document 1 identifies a target direction by delaying a received signal by a time for outputting received information detected within one hopping time.
Japanese Patent No. 3404281

  In the conventional azimuth detection receiving apparatus as described above, an operation of extracting FH waves from the reception signals based on the frequency interval between the detection signals is performed. For this reason, when FH waves arrive from a plurality of detection targets, there is a problem that it is difficult to identify the detection target. That is, there is a problem that even if a communication wave or noise by a carrier wave having a constant frequency can be separated from an FH wave, FH waves from different detection targets cannot be distinguished.

  The present invention has been made in view of the above circumstances, and an azimuth detection receiving apparatus, a target detection system, and a signal processing that improve identification accuracy when an FH wave is extracted from a received signal to identify the direction of a detection target. It aims to provide a method. In particular, it is an object of the present invention to provide an azimuth detection receiver and a signal processing method that can accurately identify a target azimuth for each detection target even when FH waves arrive from a plurality of detection targets.

  Another object of the present invention is to provide a target detection system that improves the positioning accuracy when the two-dimensional position of a detection target is determined based on the orientation identification results by a plurality of receiving devices.

The azimuth detection receiving apparatus according to the present invention receives a communication wave by frequency hopping coming from a detection target via a plurality of element antennas, digitizes the received signal for each element antenna, and generates digital reception data generation. Digital beam forming means for synthesizing digital reception data for each element antenna based on digital beam forming and forming a reception beam for each predetermined direction; and frequency analysis by Fourier transform for each formed reception beam a frequency analysis means for performing a row cormorant chip detector chip detected for each reception beam based on the result of frequency analysis, each detected target detection chip based on the appearance time interval between occurrence time length and detection chip detection chip a chip grouping unit for grouping, the same group A target direction identification means for identifying a target direction based on the detection chip for each reception beam, and a reception beam demodulating means for demodulating the reception beam based on the detection chip, the chip grouping means, the reception beam demodulator The identification information is extracted from the received beam demodulated by the means, and the detection chips are grouped based on the extracted identification information .

  In the azimuth detection receiver, digital reception data for each element antenna is synthesized based on digital beam forming, and frequency analysis is performed on each formed reception beam. Chip detection is performed based on the result of the frequency analysis, and the detection chips are grouped for each detection target to identify the target direction. At this time, grouping of detection targets is performed based on the appearance time length of each detection chip detected for each reception beam in each direction and the appearance time interval between detection chips. With such a configuration, even when communication waves due to frequency hopping arrive from a plurality of detection targets, the target direction for each detection target can be accurately identified. It is possible to improve the identification accuracy when extracting and identifying the direction of the detection target.

  According to the azimuth detection receiving apparatus and the signal processing method according to the present invention, even when a communication wave by frequency hopping arrives from a plurality of detection targets, the target azimuth for each detection target can be accurately identified. It is possible to improve the identification accuracy when extracting the communication wave by frequency hopping from the received signal and performing the direction identification of the detection target. In addition, according to the target detection system of the present invention, the target orientation for each detection target is accurately identified, so the localization accuracy when the two-dimensional position of the detection target is determined based on the orientation identification results by a plurality of receiving devices. Can be improved.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration example of an azimuth detection receiving apparatus according to Embodiment 1 of the present invention, and shows a receiving apparatus that receives a communication wave from a detection target and performs directional identification. . The azimuth detection receiver 1 according to the present embodiment transmits and receives communication data from a received signal when a detection target transmits and receives communication data by a communication wave (hereinafter referred to as an FH wave) by frequency hopping. Signal processing is performed to extract and identify the target direction.

  The azimuth detection receiver 1 includes an array antenna unit 2, a digital reception data generation unit 3, a DBF processing unit 4, a frequency analysis unit 5, a detection chip extraction unit 6, and an azimuth identification unit 7. The array antenna unit 2 is an antenna composed of a plurality of element antennas 2a that capture radio waves, and outputs a reception signal for each element antenna 2a. Each element antenna 2a is arranged on a straight line. For example, the arrangement direction is parallel to the horizontal plane. That is, the reception beam can be scanned in the horizontal direction by controlling the phase of the reception signal for each element antenna 2a. Here, this horizontal direction is taken as the azimuth direction, and the azimuth of the detection target in the horizontal plane is measured based on the electronic scanning of the received beam.

  The digital reception data generation unit 3 includes a frequency converter 3a and an A / D converter 3b provided for each element antenna 2a. The frequency converter 3a is an FH wave receiving circuit, and performs an operation of converting a received RF (Radio Frequency) signal from the element antenna 2a into an IF (Intermediate Frequency) signal.

  The A / D converter 3b performs an operation of digitizing the IF signal from the frequency converter 3a to generate digital reception data. Specifically, digital reception data is generated by sampling and quantizing the IF signal at a predetermined sampling period and encoding the quantized data. That is, the reception signal for each element antenna 2a is frequency-converted for each element antenna 2a and digitized to generate digital reception data. The digital reception data for each element antenna 2a generated in this way is output to the DBF processing unit 4 and the direction identification unit 7, respectively.

  A DBF (Digital Beam Forming) processing unit 4 synthesizes digital reception data for each element antenna 2a based on digital beam forming (DBF) as digital signal processing, and generates a reception beam for each predetermined direction. The operation to form is performed. Since this DBF scans the received beam in the azimuth direction by digital signal processing, all the received beams can be formed at the same time, which is suitable for azimuth detection based on very short time communication. Gain (gain) can be improved by such beam formation by DBF.

  The frequency analysis unit 5 performs frequency analysis on each received beam formed by the DBF processing unit 4 by Fourier transform, here, FFT (Fast Fourier Transformation).

  The detection chip extraction unit 6 performs chip detection for each received beam based on the frequency analysis result, and performs an operation of grouping the detection chips for each detection target. Specifically, chip detection is performed by threshold processing based on the signal level. The chips detected at this time (hereinafter referred to as detection chips) are grouped based on the length of the appearance time (hereinafter referred to as the appearance time length) and the appearance time interval between the detection chips.

  For example, detection chips having the same appearance time length and a constant appearance time interval are classified into the same group. Here, with respect to the appearance time interval, detection chips whose detection start times coincide with the appearance end times of the previous detection chip are sequentially extracted. That is, a detection chip in which the disappearance and appearance of the detection chip are continued on the time axis is extracted. When grouping the detection chips, the frequency band width (bandwidth) of the detection chips may be taken into consideration. In this way, by grouping the detection chips, the detection target as the FH wave transmission source can be accurately identified.

  The direction identifying unit 7 performs an operation of identifying the target direction based on the detection chip for each received beam belonging to the same group. Specifically, using the detection chip as a trigger, reception data to be subject to orientation identification is extracted from digital reception data for each element antenna 2a, and orientation detection of the detection target is performed.

  Here, it is assumed that the detection chips are narrowed down from the viewpoint of improving detection target identification accuracy. That is, azimuth detection is performed for each detection chip, and the target azimuth is identified based on the frequency distribution of the detection azimuth. Specifically, the mode value in the detected direction is output as a result of the direction identification. Thereby, since the detection chip | tip from which the detection direction has deviated largely can be excluded, the precision of direction identification can be improved.

  2A and 2B are diagrams showing an example of the detection chip extraction operation in the azimuth detection receiver of FIG. FIG. 2A shows the appearance of the detection chip A obtained by frequency analysis. FIG. 2B shows the appearance time length T of the detection chip A and the continuity between the detection chips A. The state of the detection chip extracted based on this is shown.

  Chip detection is performed by threshold processing based on frequency analysis for the received beam. The detection chips A detected at this time are grouped based on the appearance time length T and the appearance time interval between the detection chips A. In other words, detection chips having the same appearance time length T and disappearing and appearing on the time axis are extracted as belonging to the same group.

  As a result, it is possible to discriminate between communication waves and noise due to a carrier having a constant frequency and FH waves whose frequencies are switched randomly at a predetermined cycle, and it is possible to identify FH waves from different detection targets. Based on the detection chip extracted in this way, a target orientation identification process is performed.

  Steps S101 to S107 in FIG. 3 are flowcharts showing an example of signal processing related to direction identification in the direction finding receiver of FIG. First, the digital reception data generation unit 3 digitizes the reception signal for each element antenna to generate digital reception data (step S101). Next, the DBF processing unit 4 combines the digital reception data for each element antenna, and forms a reception beam for each direction (step S102).

  The detection chip extraction unit 6 performs chip detection based on frequency analysis by FFT performed on each reception beam by the frequency analysis unit 5, and groups the detection chips according to the appearance time length of the detection chips and the appearance time interval between the detection chips. (Steps S103 to S105).

  The direction identification unit 7 identifies the direction of the detection target based on the detection chip for each received beam belonging to the same group (step S106). This target azimuth identification processing is also performed for reception beams belonging to other groups, and when the azimuth is determined for all detection targets, this azimuth identification processing ends (step S107).

  According to the present embodiment, even when FH waves arrive from a plurality of detection targets, the target direction for each detection target can be accurately identified. It is possible to improve the identification accuracy when performing target orientation identification.

Embodiment 2. FIG.
In the first embodiment, the example in which the detection chips are grouped based on the appearance time length of the detection chips, the appearance time interval between the detection chips, and the bandwidth of the detection chips has been described. In contrast, in the present embodiment, a case will be described in which detection chips are grouped based on identification information extracted from a demodulated received beam.

  FIG. 4 is a block diagram showing a configuration example of the direction finding receiver according to Embodiment 2 of the present invention. Compared to the azimuth detection receiver 1 (Embodiment 1) of FIG. 1, the azimuth detection receiver 10 according to the present embodiment includes a reception beam demodulator 11, and the detection chip extraction unit 6 includes a chip detection unit 6a and a detection chip extraction unit 6. The difference is that the chip grouping unit 6b is configured.

  The chip detection unit 6a performs chip detection for each received beam, and the chip grouping unit 6b performs an operation of grouping the detection chips for each detection target.

  The reception beam demodulation unit 11 performs an operation of demodulating the reception beam based on the detection chip. Specifically, demodulation processing is performed with a demodulation method and baud rate (baud rate) corresponding to the detection chip.

  In the chip grouping unit 6b, identification information is extracted from the demodulated received beam, and detection chips are grouped based on the extracted identification information. As the identification information extracted from the reception beam, for example, a unique word included in the detection chip can be considered. This unique word is a character string, symbol, or code included in the detection chip as communication data.

  Here, it is assumed that detection chips including the same unique word are classified into the same group. By extracting such unique words from the received beam and determining the correlation between the detection chips, the detection chips can be appropriately grouped.

  According to this embodiment, since the detection chips are appropriately grouped, the identification accuracy when identifying the detection target can be further improved.

  In this embodiment, an example in which a unique word is used as identification information has been described, but the present invention is not limited to this. For example, a bit sequence of a synchronization signal included in the detection chip may be used as identification information.

  More specifically, the detection chips are grouped by extracting a bit sequence of the synchronization signal from the reception beam based on the detection chips and determining the correlation between the detection chips. Even with this configuration, the detection target identification accuracy can be improved.

Embodiment 3 FIG.
In the first and second embodiments, the example of the receiving apparatus that receives the FH wave that arrives from the detection target and identifies the direction has been described. On the other hand, in the present embodiment, a target detection system that determines a two-dimensional position of a detection target based on a direction identification result by a plurality of direction detection reception devices will be described.

  FIG. 5 is a block diagram showing a configuration example of the target detection system according to the third embodiment of the present invention. The target detection system 20 according to the present embodiment includes two direction detection reception devices 21 and a target location determination device 22 that determines the two-dimensional position of the detection target based on the direction identification result from each direction detection reception device 21. . Here, it is assumed that each azimuth detection receiver 21 is configured in the same manner as the azimuth detection receiver of FIG. 1 or FIG.

  The target locating device 22 has two-dimensional position information of each azimuth detection receiving device 21 in the horizontal plane in advance, and based on the position information and the identification result of the target azimuth transmitted from each azimuth detection receiving device 21. To identify the target position. Specifically, the two-dimensional position of the detection target is specified by the association method based on the target direction for each direction detection receiver 21, here, the two-point intersection method.

  FIG. 6 is a diagram showing an example of a target position locating operation in the target detection system of FIG. Based on the azimuth identification result by the receiving apparatus B1, an azimuth line C1 as a straight line connecting the receiving apparatus B1 and the detection target is obtained. Further, an azimuth line C2 as a straight line connecting the receiving apparatus B2 and the detection target is obtained based on the direction identification result by the receiving apparatus B2. In the two-point intersection method, the two-dimensional position of the detection target is obtained as the intersection of these azimuth lines C1 and C2.

  According to the present embodiment, since the identification accuracy of the target direction is improved, it is possible to improve the localization accuracy when the two-dimensional position of the detection target is determined based on the direction identification results obtained by the plurality of direction detection receivers. .

Embodiment 4 FIG.
In the third embodiment, an example in which the position of a detection target is determined using two azimuth detection receivers has been described. On the other hand, in this embodiment, a case will be described in which a two-dimensional position of a detection target is determined using three or more azimuth detection reception devices.

  FIG. 7 is a block diagram showing a configuration example of a target detection system according to Embodiment 4 of the present invention. The target detection system 30 according to the present embodiment includes three direction detection reception devices 21 and a target location determination device 31 that determines the two-dimensional position of the detection target based on the direction identification result from each direction detection reception device 21. .

  The target locating device 31 performs an operation of specifying the two-dimensional position of the detection target by the two-point intersection method based on the target azimuth for each azimuth detection receiving device 21. Specifically, the detection result of the target position is weighted based on the expected angle between the azimuth detection receivers 21, and the operation of specifying the target position based on this weighting is performed.

  FIG. 8 is a diagram showing an example of a target position locating operation in the target detection system of FIG. An azimuth line C1 connecting the receiving device B1 and the detection target is obtained based on the azimuth identification result by the receiving device B1, and an azimuth line C2 connecting the receiving device B2 and the detection target based on the azimuth identification result by the receiving device B2. Is required. Further, an azimuth line C3 connecting the receiving device B3 and the detection target is obtained based on the orientation identification result by the receiving device B3.

In general, the three azimuth lines C1 to C3 do not intersect at one point. Therefore, the angle formed by the two azimuth lines is set as a prospective angle θ (0 ° <θ ≦ 90 °), and the detection result of the target position is weighted based on the prospective angle θ. That is, the apparent angle between the receiving apparatus B1 and B2 and theta _12, the apparent angle between the receiving apparatus B2 and B3 and theta _23, when the visual angle between the receiving apparatus B1 and B3 and theta _13, bearing lines C1 and C2 , The intersections of the azimuth lines C2 and C3, and the intersections of the azimuth lines C1 and C3, respectively, are weighted by the corresponding prospective angle.

  For example, the intersection having the largest prospective angle is output as the two-dimensional position of the detection target. In general, the larger the prospective angle θ, the smaller the error related to the two-dimensional position determined from the intersection of azimuth lines. Therefore, the orientation of the two-dimensional position can be effectively executed by setting the two-dimensional position of the intersection having the largest prospective angle as the target position.

  Alternatively, the target position may be specified by a weighted average based on the prospective angle θ with respect to the two-dimensional position of each intersection.

  In the present embodiment, an example in which the location of a detection target is determined by the two-point intersection method has been described. However, the present invention is not limited to this, and the localization of a two-dimensional position is performed by the three-point intersection method. It may be something like doing.

  FIG. 9 is a diagram showing another example of the target position locating operation in the target detection system of FIG. In the three-point intersection method, the two-dimensional position of the detection target is specified based on the erroneous triangle formed by the three receiving devices B1 to B3.

Specifically, a false triangle is formed from three intersections of the intersection P ₁₂ of the azimuth lines C1 and C2, the intersection P ₂₃ of the azimuth lines C2 and C3, and the intersection P ₁₃ of the azimuth lines C1 and C3. A two-dimensional position is specified as the center of the tangent circle. Even with this configuration, the orientation of the two-dimensional position can be executed effectively.

Embodiment 5 FIG.
In the fourth embodiment, the example in which the position of the detection target is determined using the three azimuth detection receivers has been described. On the other hand, in the present embodiment, a case will be described in which a two-dimensional position of a detection target is determined using four or more azimuth detection reception devices.

  FIG. 10 is a block diagram showing a configuration example of a target detection system according to the fifth embodiment of the present invention. The target detection system 40 according to the present embodiment includes four direction detection reception devices 21 and a target position determination device 41 that determines the two-dimensional position of the detection target based on the direction identification result from each direction detection reception device 21. .

  The target locating device 41 performs an operation of specifying the two-dimensional position of the detection target by a three-point intersection method based on the target azimuth for each azimuth detection receiving device 21. Specifically, the target position detection result is weighted based on the area of the false triangle formed by the three azimuth detection receivers 21, and the target position is identified based on this weighting.

  FIG. 11 is a diagram showing an example of the target position locating operation in the target detection system of FIG. In this example, the false triangle P1P2P4 is formed by the receiving devices B1 to B3, and the false triangle P4P5P6 is formed by the receiving devices B2 to B4. In addition, the receiving triangles P1, P3, and B4 form an erroneous triangle P2P3P6, and the receiving devices B1, B2, and B4 form an erroneous triangle P1P3P5.

  Weighting is performed on the detection result of the target position based on the area of these false triangles. That is, the detection area defined by each of the erroneous triangle P1P2P4, the erroneous triangle P4P5P6, the erroneous triangle P2P3P6, and the erroneous triangle P1P3P5 is weighted by the corresponding area.

  For example, the target position is specified from the erroneous triangle having the smallest area. In general, the smaller the area of the false triangle, the smaller the error related to the two-dimensional position determined from the false triangle. Therefore, by obtaining the two-dimensional position of the detection target from the false triangle having the smallest area, the two-dimensional position can be effectively determined.

  Alternatively, the target position may be specified by performing a weighted average of the two-dimensional position determined from each false triangle, based on the area of the false triangle.

It is the block diagram which showed the example of 1 structure of the direction finding receiver by Embodiment 1 of this invention. It is the figure which showed an example of extraction operation | movement of the detection chip | tip in the azimuth | direction detection receiver of FIG. 3 is a flowchart showing an example of signal processing related to orientation identification in the orientation detection receiver of FIG. 1. It is the block diagram which showed the structural example of the direction finding receiver by Embodiment 2 of this invention. It is the block diagram which showed the example of 1 structure of the target detection system by Embodiment 3 of this invention. It is the figure which showed an example of the target position locating operation | movement in the target detection system of FIG. It is the block diagram which showed the example of a structure of the target detection system by Embodiment 4 of this invention. It is the figure which showed an example of the target position locating operation | movement in the target detection system of FIG. It is the figure which showed the other example of the target position locating operation | movement in the target detection system of FIG. It is the block diagram which showed the structural example of the target detection system by Embodiment 5 of this invention. It is the figure which showed an example of the target position locating operation | movement in the target detection system of FIG.

Explanation of symbols

1, 10, 21 Azimuth detection receiving device, 2 array antenna unit, 2a element antenna,
3 digital reception data generation unit, 3a frequency converter, 3b A / D converter,
4 DBF processing unit, 5 frequency analysis unit, 6 detection chip extraction unit, 6a chip detection unit,
6b Chip grouping unit, 7 Direction identification unit, 11 Receive beam demodulation unit,
20, 30, 40 target detection system, 22, 31, 41 target orientation device,
A detection chip, T appearance time length

Claims (3)

Digital reception data generating means for receiving a communication wave by frequency hopping coming from a detection target via a plurality of element antennas, digitizing a reception signal for each element antenna and generating digital reception data;
Digital beam forming means for synthesizing digital reception data for each element antenna based on digital beam forming and forming a reception beam for each predetermined direction;
Frequency analysis means for performing frequency analysis by Fourier transform for each formed reception beam;
A row Cormorant chip detector chip detected for each reception beam based on the result of frequency analysis,
Chip grouping means for grouping detection chips for each detection target based on the appearance time length of the detection chips and the appearance time interval between the detection chips ;
Target azimuth identifying means for identifying the target azimuth based on the detection chip for each received beam belonging to the same group ;
Receiving beam demodulation means for demodulating the received beam based on a detection chip;
The azimuth detection receiving apparatus characterized in that the chip grouping means extracts identification information from the reception beam demodulated by the reception beam demodulation means, and groups detection chips based on the extracted identification information . The azimuth detection receiving apparatus according to claim 1, wherein the chip grouping means groups detection chips using a unique word included in the detection chip as identification information. The azimuth detection receiving apparatus according to claim 1, wherein the chip grouping means performs grouping of detection chips by using a bit sequence of a synchronization signal included in the detection chip as identification information.

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