JP2018084432A - Radar system and radar signal processing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To output a highly accurate position of an object by reducing effect of a time error due to separate arrangement of a plurality of radar devices.SOLUTION: A radar system of an embodiment comprises Ntr ((Ntr≥2) transmitter-receiver. The transmission-side device transmits an at least pulse modulated signal of an up or a down sweep having a frequency sweep gradient after modulation, with communication information that includes a position, a transmission frequency and a transmission time as a modulated signal. The receiving-side device: sweeps a local signal the same way as the transmission-side device; receives a direct wave from the transmission-side devices or a reflected wave from an object; changes an FFT (Fast Fourier Transmission) start time in multiple ways and selects a start time at which an FFT output is maximum; evens out a received local signal on the basis of the demodulated communication information after demodulating the communication information and causes the evened received local signal to synchronize with the received signal; corrects a reference signal for pulse compression; performs a pulse compression process using the corrected reference signal; performs object detection and distance measurement and, if necessary, angle measurement of the object; and calculates the three-dimensional or two-dimensional position of the object.SELECTED DRAWING: Figure 1

Description

  The present embodiment relates to a multistatic radar system and a radar signal processing method thereof.

  Recently, in the radar system, a multi-static method has been developed in which a plurality of transmission / reception radar devices or a plurality of transmission devices and a reception radar device are arranged apart from each other and a target position is detected based on the observation result of each radar device. Has been. However, in this type of radar system, if the time synchronization between the separated radar devices is insufficient or the distance accuracy is insufficient, the error of the observation position becomes large. Further, when the transmitting device is out of line of sight, direct waves cannot be received, and synchronized multi-static operation cannot be performed.

Pulse compression, Ouchi, “Basics of Synthetic Aperture Radar for Remote Sensing”, Tokyo Denki University Press, pp.131-149 (2003) Phase monopulse (phase comparison monopulse) system, Yoshida, 'Revised radar technology', IEICE, pp.262-264 (1996) Taylor distribution, Yoshida, 'Revised radar technology', IEICE, pp.134-135 (1996) OFDM, Nishimura, ‘Communication system design by digital signal processing’, CQ Publisher, pp.248-269 (2006) BPSK, QPSK, Nishimura, 'Communication system design by digital signal processing, CQ Publisher, pp.222-226 (2006) MIMO processing, JIAN LI, PETER STOICA, ‘MIMO RADAR SIGNAL PROCESSING’, WILEY, pp.1-5 (2009)

  As described above, in the conventional multistatic radar system, the beat frequency cannot be observed accurately due to the influence of the time synchronization deviation or the center frequency deviation between the radar devices, and the target three-dimensional position is calculated. Above, the distance accuracy is insufficient, and the small receiving device has a problem that the angle measurement accuracy is low.

  The present embodiment has been made in view of the above problems, and reduces the influence of time synchronization deviation and center frequency deviation between radar devices, improves beat frequency observation accuracy, and sets the target three-dimensional or two-dimensional position. An object of the present invention is to provide a radar system and a radar signal processing method thereof that can obtain sufficient distance accuracy for calculation and can obtain high angle measurement accuracy even with a small receiver.

  In order to solve the above problems, the radar system according to the present embodiment includes Ntr (Ntr ≧ 2) transmission / reception devices. The transmission side apparatus modulates and transmits at least a pulse-modulated signal of an up sweep or a down sweep having a frequency sweep gradient using communication information including a position, a transmission frequency, and a transmission time as a modulation signal. In the receiving side device, the local signal is swept in the same manner as the transmitting side device, the direct wave from the transmitting side device or the reflected wave from the target is received, and the FFT (Fast Fourier Transform) start time is changed in several ways to output the FFT. After selecting the start time that maximizes the frequency and demodulating the communication information, the received local signal is made constant based on the demodulated communication information and synchronized with the received signal, and the reference signal for pulse compression is corrected. Then, pulse compression processing is performed using the corrected reference signal, target detection and distance measurement, and angle measurement as necessary, and the target three-dimensional position (x, y, z) or two-dimensional position (x , Y).

1 is a block diagram showing a configuration of a radar system according to a first embodiment. The wave form diagram for demonstrating the time synchronization of the radar system which concerns on 1st Embodiment. The wave form diagram which shows the mode of the transmission side modulation | alteration of the radar system which concerns on 1st Embodiment, and the receiving side demodulation. The wave form diagram for demonstrating the local control process in the demodulation process of the communication information of the radar system which concerns on 1st Embodiment. The wave form diagram for demonstrating the received signal synchronization and the tuning process of the radar system which concerns on 1st Embodiment. In the radar system which concerns on 1st Embodiment, the conceptual diagram which shows the coordinate system for demonstrating the distance observation and AZ, EL observation of target position identification by transmission / reception of communication information. The conceptual diagram which shows a mode that the transmission beam and several receiving beam are formed with respect to the target in the radar system which concerns on 1st Embodiment. The block diagram which shows the structure of the radar system which concerns on 2nd Embodiment. The block diagram which shows the structure of the radar system which concerns on 3rd Embodiment. The conceptual diagram which shows a mode that the position of a target is identified using the fitting by a range in the radar system which concerns on 3rd Embodiment in a three-dimensional coordinate system. The block diagram which shows the structure of the radar system which concerns on 4th Embodiment. The block diagram which shows the structure of the radar system which concerns on 5th Embodiment. The block diagram which shows the structure of the radar system which concerns on 6th Embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. In the description of each embodiment, the same portions are denoted by the same reference numerals, and redundant description is omitted.

(First Embodiment) Reference signal correction pulse compression and transmission / reception apparatus by communication demodulation A radar system according to a first embodiment will be described with reference to FIGS.

  This radar system includes Ntr transmission / reception devices TR1 to TRNtr (Ntr = 3 in FIG. 1) having the same configuration. The transmission / reception device TRi (i is any one of 1 to Ntr, i = 3 in FIG. 1) includes a transmission device Ti and a reception device Ri.

  In the transmission / reception apparatus TRi, the transmission / reception apparatus TR1 with i = 1 will be described as a representative.

  The transmission device T1 includes a transmission antenna T11 and a transmitter T12, and the transmitter T12 includes a transmission unit T121 and a transmission modulation unit T122.

  The receiving device R1 includes a receiving antenna R11, a receiver R12, and a signal processor R13. The receiver R12 includes a receiving unit R121, a local control unit R122, a timing control unit R123, and a beam pointing direction control unit R124. The signal processor R13 includes a Σ1 beam system, a Σ2 beam system, and a Δ beam system. The Σ1 beam system includes an AD (Analog-Digital) conversion unit R131, an FFT (Fast Fourier Transform) weight unit R132, an FFT processing unit R133, a CFAR processing unit R134, a demodulation unit R135, a control signal generation unit R136, and a reference signal generation unit R137 is provided. The Σ2 beam system includes an AD conversion unit R138, a PC (Phase-controller) weight unit R139, a PC processing unit R13a, a CFAR processing unit R13b, a distance measuring unit R13c, an angle measuring unit R13d, and a position identifying unit R13e. The Δ beam system includes an AD conversion unit R13f, a PC (Phase-controller) weight unit R13g, and a PC unit R13h.

  In the transmission device T1, the transmission antenna T11 is a phased array antenna formed by arranging a plurality of antenna elements to form a large aperture array, and transmits a transmission signal of a specific frequency repeatedly supplied from the transmitter T12 in a specified direction. To do. In the transmitter T12, a transmission signal modulated by communication information such as a transmission position, a transmission time, and a transmission frequency in the transmission modulation unit T121 is transmitted to the transmission antenna T11 by the transmission unit T122.

  In the receiving device R1, the receiving antenna R11 is a phased array antenna in which a plurality of antenna elements are arranged to form a large aperture array as in the transmission system, and is transmitted from the transmitting device T1 and another transmitting / receiving device TR1. Receive the reflected wave of the transmitted wave. In the receiver R12, the reception unit R121 forms a reception beam in an arbitrary direction by performing phase control on the signals respectively received by the plurality of antenna elements of the reception antenna R11 according to the beam control instruction and combining them. And convert the frequency to baseband. The reception signal obtained in this way is sent to the signal processor R13.

  The signal processor R13 distributes the received signal to the Σ1, Σ2 beam system and the Δ beam system.

  The received signal input to the Σ1 beam system is converted into a digital signal by the AD conversion unit R131, multiplied by a weight as FFT preprocessing by the FFT weight unit R132, and subjected to FFT processing by the FFT processing unit R133 and Σ in the frequency domain. After conversion into a beam signal, detection of cells (frequency samples) exceeding a predetermined threshold is executed by the CFAR processing unit R134. Subsequently, in the demodulation unit R135, communication information such as a transmission position, a transmission time, and a transmission frequency is demodulated for the CFAR detection cell. The demodulated communication information is sent to the control signal generator R136 and the reference signal generator R137. The control signal generation unit R136 generates a local frequency control signal for the local control unit R122, a timing control signal for the timing control unit R123, and a beam pointing direction control signal for the beam pointing direction control unit R124 based on the communication information. . The reference signal generation unit R137 generates a reference signal for the Σ2 system PC processing unit R13a.

  The received signal input to the Σ2 beam system is converted into a digital signal by the AD conversion unit R138, multiplied by the weight as the PC preprocessing by the PC weight unit R139, and PC-processed by the PC processing unit R13a, and the time domain Σ After conversion to the beam signal, detection of cells (time samples) exceeding a predetermined threshold is executed by the CFAR processing unit R13b. Subsequently, the distance and direction from the CFAR detection cell to the target are calculated by the distance measurement and angle measurement processing of the distance measurement unit R13c and angle measurement unit R13d, the position of the target is identified by the position identification unit R13e, and the observation result Is output.

  The received signal input to the Δ beam system is converted into a digital signal by the AD conversion unit R13f, multiplied by a weight as PC preprocessing by the PC weight unit R13g, and subjected to PC processing by the PC processing unit R13h, and Δ in the time domain. After being converted into a beam signal, it is sent to the angle measuring unit 236 and used for angle measurement calculation.

  In the radar system according to the present embodiment, the transmission / reception devices TRi are separated from each other. Therefore, the present embodiment provides a method for adjusting the time synchronization between the transmission / reception apparatuses TRi with high accuracy.

  First, time synchronization will be described with reference to FIGS. As shown in FIGS. 2 (a) and 2 (b), the signal waveform includes an up sweep (down sweep) in a transmission sweep (for communication modulation) on the transmission side and a local sweep (for communication demodulation) on the reception side. Good) Waveform shall be adopted. On the receiving side, as shown in FIG. 2 (b), a local signal with a constant level (not swept) is also generated for target observation.

  First, in the transmission device T1, as shown in FIG. 3A, the transmission modulation unit T122 uses BPSK (see Non-Patent Document 5) on the beat frequency axis as communication information such as a transmission position, a transmission time, and a transmission frequency. Phase code (modulation code (amplitude constant)) is generated, and a modulation waveform is generated by inverse FFT as shown in FIG. 3B, and the transmission period shown in FIG. A modulated signal is generated by pulse-modulating the sweep signal. This is equivalent to multi-carrier modulation by OFDM (see Non-Patent Document 4). This modulated signal is output to transmitter T121.

  In the transmission unit T121, the carrier signal is modulated by the modulation signal pulse-modulated by the sweep signal, and the power is amplified to generate a transmission signal. This transmission signal is transmitted from the transmission antenna T11. The transmission antenna T11 is assumed to be an antenna having wide-angle directivity. However, when the target direction is in a limited range, the transmission antenna T11 may have transmission directivity that covers that direction.

Here, the modulation signal is formulated as follows. First, the sweep waveform before modulation can be generally expressed by the following equation.

Next, considering the modulation waveform, for example, in the case of BPSK (see Non-Patent Document 5), the following equation is obtained.

If this is inverse FFTed, a time-axis modulated signal is obtained.

Using this, the modulation signal becomes the following equation.

  The carrier signal having the center frequency fc is modulated by this modulation signal to obtain a transmission waveform. At the time of demodulation, as shown in FIGS. 3D and 3E, a modulation code is extracted by performing FFT processing on the complex amplitude waveform of the received signal and detecting the phase change of the beat frequency.

  In order to synchronize the time of the receiving device R1, there is a time synchronization adjustment method using a GPS (Global Positioning System) and an atomic clock. However, since a time error occurs, sufficient time synchronization is difficult. Therefore, in the present embodiment, a technique is adopted in which communication information such as a transmission position, a transmission time, and a transmission frequency superimposed from a radar wave reception signal is extracted and used for reception processing.

  In this case, there are a case where a direct wave from the transmission source can be received and a case where transmission and reception are out of line of sight and are received as a target reflected wave. In order to extract communication information, it is necessary to receive with high SN. For this reason, the timing controller R123 changes the start time Δt of the sweep frequency for demodulation as shown in FIGS. 4 (a) and 4 (b) by Nt, and after each FFT processing shown in FIG. 4 (c). The synchronized Δtsel is selected according to the maximum value of the target signal. With this selected Δtsel, the communication information when received is demodulated as shown in FIG. As this method, it is possible to demodulate the phase change when it exceeds a predetermined amplitude threshold by making it correspond to 0 (0 degree) and 1 (180 degree).

  At this time, since the phase due to the beat frequency component is included in addition to the communication information, the influence is suppressed. For this purpose, after detecting the beat frequency, as shown in FIGS. 4E to 4G, the phase gradient due to the center frequency of the beat frequency is detected, and the phase gradient for the center frequency is deleted from the phase component by IFFT. After the correction, FFT is performed to move the center beat frequency to near 0 Doppler. As a result, the influence of the phase gradient is suppressed, and it becomes easy to extract the phase that is phase-modulated (BPSK or the like) by the communication information.

  If the transmission time of the transmission source can be obtained by demodulating communication information, the local signal is then made constant, and pulse compression processing for target signal detection and distance measurement (see Non-Patent Document 1) is performed. . For this purpose, a control signal is generated by the control signal generator R136, and the timing shift between the received signal on the time axis shown in FIG. 5A and the local signal is shown in FIG. 5B by the timing controller R123. To correct. The communication information includes the transmission frequency of the transmission source. Therefore, by adjusting the local (constant value) frequency to the correct local frequency according to the value of the transmission frequency by the local control unit R122, the Doppler frequency can be accurately observed by FFT processing between pulses. This FFT processing is omitted in this embodiment. The received signal is converted into a digital signal by the AD converter R131.

  For pulse compression, it is necessary to correct the reference signal including the communication code. For this reason, the reference signal generator R137 corrects the reference signal when it is generated. The pulse compression is a correlation process between an input signal and a pulse compression signal. The case where this is performed in the frequency domain is formulated as follows.

First, the input signal is as follows.

Next, the reference signal is as follows.

When multiplied by the signal on the frequency axis, the following equation is obtained.

The pulse compression output fp can be calculated by inverse FFT of fcs.

At this time, since the input signal Sin is communication-modulated and cannot be matched with the reference signal, the compressed waveform is disturbed. For this measure, the reference signal is corrected.

The reference signal is corrected using this as follows.

Using this Sref_cal, pulse compression may be performed using equations (7) and (8).

  The angle measurement is performed by phase monopulse angle measurement (see Non-Patent Document 2) or the like using a difference (Δ) signal by a Δ pattern system in addition to a sum (Σ) signal as shown in FIG.

  Although this embodiment demonstrated the case where there exist a some transmission / reception apparatus, even when one set is set as transmission and the other one is received among the remote transmission / reception apparatuses, a target position can be identified. That is, for example, as shown in FIG. 6, the distance between the transmission side device TR1 and the target-reception side device TR2, the target AZ and EL angle values as viewed from the reception side device TR2, and the transmission position included in the communication information are identified. Thus, the target position can be identified.

  Hereinafter, an operation example using a communication-modulated transmission / reception apparatus will be described. If it is a transmission / reception apparatus, it can be used as a transmission apparatus or a reception apparatus during multi-static operation.

  Therefore, by extracting the beam schedule of the transmission side device TR1 from the communication information, the reception side device TR2 forms a reception beam according to the transmission direction, frequency, etc., making unnecessary transmission unnecessary and observing the observation range efficiently. can do. An example is shown in FIG. With respect to the transmission beam of the transmission side apparatus TR1, the reception beams of the reception side apparatuses TR2 and TR3 at two different sites can be controlled and observed without waste.

  When observing between a plurality of multi-static devices, a database of the observation range, the position of the transmitting device, the beam pointing direction, etc. when a target with a high SN (signal power / noise power) is obtained is stored in the database. By using this information in subsequent observations, learning effects including the environment can be expected.

  At the time of calibration, the position is communication-modulated with respect to the target position observed by one transmission / reception device, and transmitted to another transmission / reception device. Thereby, the position in the case of multistatic observation can be corrected by the reference position.

  In this embodiment, the position of the transmission side device is discriminated by demodulating the modulation signal from the transmission side device, and isolation between transmission waves of MIMO (Multiple Input Multiple Output, see Non-Patent Document 6) is performed. It can be said that it is a technique to take. If transmission wave isolation can be ensured, a transmission / reception array signal by MIMO can be formed, and a transmission / reception beam having a high degree of freedom can be formed.

  As described above, in the radar system according to the present embodiment, in Ntr (Ntr ≧ 2) transmission / reception apparatuses, up-sweep having a frequency sweep gradient using communication information such as position, transmission frequency, and transmission time as modulation signals Modulates and transmits at least one pulse-modulated signal of down sweep, and in reception of other transmitting / receiving devices, sweeps a local signal in the same manner as transmission, receives a direct wave or a reflected wave from a target, and receives the received signal After selecting the start time that maximizes the FFT output when the FFT start time is changed in multiple ways and demodulating the communication information, the demodulated signal is used to synchronize with the received local signal constant, and for pulse compression The reference signal is corrected, pulse compression processing is performed using the corrected reference signal, target detection and distance measurement are performed, and angle measurement is performed as necessary. Dimension position (x, y, z) or two-dimensional position (x, y) is calculated.

  According to this configuration, the position, transmission timing, and transmission frequency of the transmitting side device are extracted from the communication information, synchronized and tuned, and pulse compression is performed using the corrected reference signal, and the target is observed with high resolution on the range axis. In addition, by extracting the transmission beam schedule from the communication information, the reception apparatus (transmission / reception apparatus) can form a reception beam according to the transmission direction, frequency, etc., and can efficiently observe the observation range.

(Second Embodiment) Separation of Transmitting Device and Receiving Device In the first embodiment, the case where a radar system is configured by a plurality of transmitting / receiving devices has been described. In the present embodiment, a case where the transmission device and the reception device are separated will be described. The system is shown in FIG.

  8, transmitters TA1 to TANt (Nt ≧ 2, Nt = 2 in FIG. 8) each include a transmission antenna T11, a transmission unit T121, and a transmission modulation unit T122 similarly to the transmission device T1 illustrated in FIG. It consists of a container T12. These transmitters TA1 to TANt may be of a simple type that forms a transmission beam that covers a wide observation range, but may be one in which a transmission antenna can perform beam scanning. In that case, the beam schedule is included in the communication information. On the other hand, the communication demodulation method, pulse compression processing, and the like of the receiving devices RA1 to RANr (Nr ≧ 1, Nr = 1 in FIG. 8) are the same as those of the receiving device R1 of the first embodiment. The description is omitted. Note that the receiving devices RA1 to RANr in this embodiment do not include the position identifying unit R13e, and use the output of the angle measuring unit R13d as an observation value.

  If the target angle measurement value and the transmission position obtained from the communication information are known as seen from the receiving device RA1, the target three-dimensional position can be identified by observing the transmission to reception distance.

  That is, in the radar system according to the present embodiment, at least one of the up sweep and the down sweep having a frequency sweep gradient is used in the Nt transmitters TA1 to TANt using communication information such as position, transmission frequency, and transmission time as modulation signals. A carrier signal is modulated and transmitted using two pulse-modulated signals. Further, in the Nr receivers RA1 to RANr, the local signal is swept in the same way as the transmission, and the direct wave or the reflected wave signal from the target is subjected to FFT processing when the FFT start time is changed in a plurality of ways. Select the start time that maximizes the FFT output, demodulate the communication information from the FFT processing output, then synchronize the received local signal using the demodulated signal, and correct the reference signal for pulse compression Then, pulse compression processing is performed using the corrected reference signal, and detection, distance measurement, and angle measurement are performed as necessary, and the target three-dimensional position (x, y, z) or two-dimensional position (x, y) Is calculated.

  As described above, according to the above embodiment, when the transmission device and the reception device are separated, the communication information is synchronously tuned, the pulse is compressed using the corrected reference signal, and the range axis has high resolution. The target can be observed.

(Third embodiment) Reference signal correction pulse compression by communication demodulation and three-dimensional position identification In the second embodiment, the target position is determined by using the angle measurement values of AZ and EL and the distance from transmission to reception as viewed from the receiving apparatus. The method of identifying is described. In this case, when the receiving device is relatively large and the angle measurement accuracy is high, the three-dimensional position accuracy is high. However, when the receiving device is small, the angle measurement accuracy is low and the position accuracy is low. In this embodiment, a technique for identifying a three-dimensional position using a plurality of transmission to reception distances is mainly described as a countermeasure.

  FIG. 9 shows a system diagram of this embodiment. In FIG. 9, transmitters TA1 to TANt are configured in the same manner as in the second embodiment, but here Nt ≧ 3. Receiving devices RB1 to RBNr (Rr = 1 in the figure) have a configuration in which a position identifying unit R13e is added to the receiving device RA1 of the second embodiment.

  As shown in FIG. 10, when there are three transmission devices TANt, the same processing is performed for the reception device RA1, and transmission device TA1 to target to reception device RB1, transmission device TA2 to target to reception device RB1, and transmission device TA3. R1, R2, R3 can be obtained as the distances from the target to the receiving device RB1. The system is shown in FIG.

Using this distance, a target position (x, y, z) is calculated as shown in FIG. This method is an intersection of ellipsoidal spheres R1, R2 and R3. Among them, a predetermined range is set as a target existing area around the three-dimensional position in the AZ angle and EL angle directions observed by the receiving device RB1, and an intersection in the area is calculated. For this purpose, the points in the target existence area are divided into (x, y, z) grid points, and the point (x, y, z) at which the value of the following equation is the minimum at each point is calculated.

  If the receiving device has a transmission function, even if the number of transmitting devices is two, the midpoint of the intersection line in the same method can be output as the target three-dimensional observation position.

  Further, for example, in the case of one transmission apparatus, if there are three reception apparatuses, the distances R1 to R3 can be obtained in the same manner, so that a three-dimensional position can be determined by the same method. Further, in the case of a plurality of transmission apparatuses, a radar with a low target SN may be included. However, if a three-dimensional position is calculated as it is, a position error may increase. For this measure, it is preferable to provide a predetermined threshold for the SN value and calculate the position using values of the transmitting device to the receiving device that are equal to or higher than the threshold.

  In the above embodiment, the case where the target three-dimensional position is output has been described. However, in the case where the target two-dimensional position (x, y) is output, the number of transmission apparatuses + reception apparatuses is the number of transmissions. It is sufficient that two devices + one or more receiving devices or one transmitting device + two or more receiving devices.

  Further, in the third embodiment, by calculating the intersection of the coordinate system from the distance R of the three sets (two sets in the case of two dimensions) of the transmission device and the reception device and the angle measurement value of the reception device, A three-dimensional or two-dimensional position can be calculated.

  As described above, according to the radar system of the third embodiment, the target three-dimensional position is identified using the distance between the transmission device and the reception device even when the angle measurement accuracy of the reception device is low. be able to.

(Fourth Embodiment) Transmission Isolation In the first and second embodiments, a method using a communication modulation code has been described in order to isolate (discriminate) between transmission / reception apparatuses or between transmission apparatuses. In this embodiment, in order to further improve the isolation between the transmission apparatuses, at least one of the center frequency of the plurality of transmission apparatuses (Nt ≧ 2) or the frequency gradient of the sweep signal is changed for each transmission apparatus. Adopt the method.

  FIG. 11 shows the system configuration. In FIG. 11, the transmission modulation unit T122 ′ of each of the transmission devices TB1 to TBNt changes the sweep time by making the center frequency, the sweep frequency band, or the sweep frequency band the same for each transmission device. Thereby, the frequency sweep gradient can be changed.

  On the receiving device RB1 side, in the case of communication demodulation, the received local signal is swept, but in order to receive signals from the transmitting devices TB1 to TBNt, the local control unit R122 supports Nr sweeps. A communication signal is detected by receiving sequentially in a sweep. When the reception system has Nr channels, parallel processing is performed, and when there is only one channel, it is necessary to switch to receive in time series.

  Since the receiving unit R121 and the AD converting unit R131 receive only a signal having a predetermined bandwidth according to the beat frequency, signals from transmission devices having different sweep signal bands are used except when the transmission and reception sweep bands do not match. Do not receive. For this reason, it is possible to ensure isolation between the transmission apparatuses.

  Thereby, after demodulation, pulse compression is performed with the reception local sweep signal at a constant frequency for target observation. At this time, by reflecting the sweep gradient of the transmission device in the reference signal, the transmission device can be discriminated and received by the difference in the sweep gradient.

  As described above, in the radar system according to the fourth embodiment, at least one of the center frequency and the frequency gradient of the sweep signal is changed for each transmission device in the case of a plurality of transmission devices. Since the transmission is isolated and the correct transmission position information is used, the target position can be identified.

(Fifth Embodiment) Coordination Between Transmissions This embodiment describes a case where information can be shared between transmission apparatuses. Since the transmission device has a transmission function, if it has a reception function for demodulating communication, the communication information is shared between the transmission devices by demodulating the reception signal of the direct wave or the reflected wave from the target. it can. The system of the radar system in this case is shown in FIG.

  In FIG. 12, a transmission device TC1 (TC2 to TCNt has the same configuration and description thereof is omitted here) includes a signal processor T13 and a position driving device T14 in addition to the transmission antenna T11 and the transmitter T12.

  In the signal processor T13, the modulation signal generation unit T131 generates a modulation signal including communication information such as a transmission position, a transmission time, and a transmission frequency, and outputs the modulation signal to the transmission modulation unit T122 of the transmitter T12.

  The transmission output of the transmitter T12 is received by the reception unit T132 of the signal processor T13, converted into a digital signal by the AD conversion unit T133, and then multiplied by a weight as an FFT preprocessing by the FFT weight unit T134. After being subjected to FFT processing in T135 and converted into a Σ beam signal in the frequency domain, detection of cells (frequency samples) exceeding a predetermined threshold is executed in the CFAR processing unit T136. Subsequently, the demodulation unit T137 demodulates communication information such as a transmission position, a transmission time, and a transmission frequency for the CFAR detection cell. The demodulated communication information is sent to the position control unit T138 and the beam directing direction control unit T139.

  The position control signal generation unit T138 detects a position change of the transmission device TC1 based on the communication information, and controls the position driving process of the position driving device T14 based on the detection result. The beam directing direction control unit T139 controls the beam directing direction of the transmission antenna T11 based on the demodulated communication information.

  Since each of the transmission devices TC1 to TCNt has the same configuration, when the description is continued by taking the transmission device TC1 as an example, the communication information of the other transmission devices is demodulated by the reception / demodulation processing of the communication information. In order to transmit, the modulation signal generation unit T131 generates a modulation signal and sends it to the transmission modulation unit T122. As a result, if the predetermined observation range is known in advance, it is possible to perform control for optimizing the position of the transmission device and the beam directing direction so as to form a transmission beam that covers the predetermined observation range between the transmission devices.

  As described above, the radar system according to the fifth embodiment has a reception function capable of performing communication demodulation of the transmission wave to the transmission device, and by sharing communication information between the transmission devices, the transmission position and the beam directing direction are It becomes possible to set to a predetermined observation range. Thereby, it is possible to optimally control the position of the transmitter and the beam directing direction according to a predetermined observation range.

(Sixth Embodiment) Coordination Between Transmission / Reception In the fifth embodiment, an information sharing technique only between transmitting apparatuses is described. In this embodiment, a technique capable of further sharing information with a receiving apparatus is described.

  The system system of this embodiment is shown in FIG. In FIG. 13, the receiving device RC1 includes a simple communication device R13i including a wire to suppress radio wave radiation from others as much as possible. In the case of wireless, it is wired to a position as far as possible from the receiving apparatus, and information is transmitted wirelessly from that position to the transmitting apparatus. Since the configurations of the other transmitting devices and receiving devices are the same as those in FIG. 12, the description thereof is omitted here.

  The communication information to be transmitted includes power ON / OFF of the transmission apparatus, transmission timing, transmission frequency, transmission frequency sweep band, observation range (beam directing direction), position of the transmission apparatus, and the like.

  When the transmission device in the vicinity of the reception device RC1 demodulates the communication information of the reception device, the transmission device modulates the transmission wave for transmission to another transmission device. As a result, information can be shared between transmitting apparatuses including the receiving apparatus. As a result, since information can be shared from the transmission device to the reception device, it is possible to optimally control the position of the transmission device, the direction of the transmission beam / reception beam, etc. in order to observe a target within a predetermined range. Become.

  In this embodiment, communication from the receiving device to the transmitting device is performed using the communication device R13i. However, in the first embodiment, communication information is superimposed on radar waves between a plurality of transmitting and receiving devices. Functions similar to those in the embodiment can be provided.

  In this embodiment, the transmission device has a reception function. For this reason, it is possible to observe the target with the transmission device and modulate and transmit the target position information to the transmission wave to the reception device side, but there is a problem that the reception scale of the transmission device increases. Therefore, in the present embodiment, the reception function of the transmission device is set as simple as possible.

  Similarly, the communication function of the receiving apparatus is a simple communication function because it is characterized by not transmitting radio waves as much as possible.

  As described above, the radar system according to the sixth embodiment transmits a communication information signal for transmission control from a receiving apparatus through communication processing to Ntp (Ntp ≧ 1) transmitting apparatuses. Then, information is shared and controlled by receiving a transmission wave between the transmitting apparatuses. In other words, it is possible to optimally control the transmission position and the beam directing direction using information obtained by observing the receiving side on the receiving side using the minimum necessary communication means.

  Note that the present embodiment is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

TR1 to TRNtr ... transmitting / receiving device,
Ti (T1), TA1 to TANt, TB1 to TBNt, TC1 to TCNt ... transmitting device,
T11: transmitting antenna,
T12 ... transmitter, T121 ... transmission unit, T122, T122 '... transmission modulation unit,
T13: Signal processor, T131: Modulation signal generator, T132: Receiver, T133: AD converter, T134: FFT weight unit, T135: FFT processor, T136: CFAR processor, T137: Demodulator, T138 Position control unit, T139, beam directing direction control unit,
T14: Position driving device,
Ri (R1), RA1 to RANr, RB1 to RBNr, RC1 to RCNr ... receiving device,
R11: receiving antenna,
R12 ... Receiver, R121 ... Receiver, R122 ... Local controller, R123 ... Timing controller, R124 ... Beam pointing direction controller,
R13 ... signal processor, R131 ... AD converter, R132 ... FFT weight unit, R133 ... FFT processor, R134 ... CFAR processor, R135 ... demodulator, R136 ... control signal generator, R137 ... reference signal generator, R138: AD conversion unit, R139: PC weight unit, R13a: PC processing unit, R13b: CFAR processing unit, R13c: Distance measuring unit, R13d: Angle measuring unit, R13e: Position identifying unit, R13f: AD converting unit, R13g ... PC weight part, R13h ... PC part, R13i ... communication device.

Claims (7)

In a radar system including Ntr (Ntr ≧ 2) transceivers,
The transmitting / receiving apparatus modulates and transmits at least one pulse-modulated signal of an up sweep or a down sweep having a frequency sweep gradient with communication information including a position, a transmission frequency, and a transmission time as a modulation signal,
The transmission / reception device on the reception side sweeps the same local signal as the transmission / reception device on the transmission side, receives the direct wave from the transmission / reception device on the transmission side or the reflected wave from the target, and sets the FFT (Fast Fourier Transform) start time. After selecting the start time at which the FFT output is maximized by changing a plurality of modes, demodulating the communication information, the received local signal is made constant based on the demodulated communication information and synchronized with the received signal, and pulse compression is performed. The reference signal is corrected, pulse compression processing is performed using the corrected reference signal, target detection and distance measurement, and angle measurement as necessary, and the target three-dimensional position (x, y, z ) Or a radar system for calculating a two-dimensional position (x, y). In a radar system comprising Nt (Nt ≧ 1) transmitters and Nr (Nr ≧ 1, Nt + Nr ≧ (4,3) (three-dimensional position identification, two-dimensional position identification)) receivers,
The transmission device modulates and transmits at least one pulse-modulated signal of an up sweep or a down sweep having a frequency sweep gradient using communication information including a position, a transmission frequency, and a transmission time as a modulation signal,
The receiving device sweeps a local signal in the same manner as the transmitting device, receives a direct wave from the transmitting device or a reflected wave from a target, and changes a plurality of FFT (Fast Fourier Transform) start times. After selecting the start time at which the FFT output is maximized and demodulating the communication information, the received local signal is made constant based on the demodulated communication information and synchronized with the received signal, and the reference for pulse compression The signal is corrected, pulse compression processing is performed using the corrected reference signal, target detection, distance measurement, and angle measurement as necessary, and the target three-dimensional position (x, y, z) or 2 A radar system for calculating a dimensional position (x, y). When angle measurement is performed by the receiving side transmitting / receiving device or the receiving device,
The intersection is calculated from three or more distances between the transmitting / receiving device or the transmitting device and the receiving / receiving device or the receiving device, and the measured angle of the receiving / transmitting device or the receiving device. The radar system according to claim 1, wherein the three-dimensional or two-dimensional position of the target is calculated by   The at least one of a center frequency and a frequency gradient of a sweep signal is changed for each transmission / reception apparatus or each transmission apparatus when there are a plurality of transmission / reception apparatuses or transmission apparatuses on the transmission side. 4. The radar system according to any one of 3. The transmission / reception device or the transmission device on the transmission side includes reception means for performing communication demodulation of a transmission wave,
5. The communication information is shared with other transmitting / receiving devices or the transmitting device, and the transmission position and the beam directing direction are set to a predetermined observation range based on the communication information. The described radar system. The receiving-side transmitting / receiving device or the receiving device includes Ntp (Ntp ≧ 1) transmitting-side transmitting / receiving devices or communication means for transmitting a transmission control signal to / from the transmitting device,
The transmitting / receiving device or the transmitting device includes receiving means for receiving a transmission wave with another transmitting / receiving device or the transmitting device,
The radar system according to any one of claims 1 to 5, wherein each of the reception-side transmission / reception device or the reception device, the transmission-side transmission / reception device, or the transmission device shares and controls received information. Used in radar systems equipped with Ntr (Ntr ≧ 2) transceivers,
In the transmission / reception device on the transmission side, communication information including position, transmission frequency, and transmission time is used as a modulation signal, and at least one pulse-modulated signal of up sweep or down sweep having a frequency sweep gradient is modulated and transmitted.
The receiving-side transmitting / receiving device sweeps the same local signal as the transmitting-side transmitting / receiving device, receives a direct wave from the transmitting-side transmitting / receiving device or a reflected wave from the target, and sets an FFT (Fast Fourier Transform) start time. After selecting the start time at which the FFT output is maximized by changing a plurality of modes, demodulating the communication information, the received local signal is made constant based on the demodulated communication information and synchronized with the received signal, and pulse compression is performed. The reference signal is corrected, pulse compression processing is performed using the corrected reference signal, target detection and distance measurement, and angle measurement as necessary, and the target three-dimensional position (x, y, z Or a radar signal processing method of a radar system for calculating a two-dimensional position (x, y).

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