JP2015169507A - Radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar device capable of promptly adjusting wave fronts among receiving systems without setting a specific receiving system in an array antenna as a reference.SOLUTION: If switching control means 32 selects a reference signal to serve as a phase reference pilot signal, then phase detection means detects a phase of each of signals input from a plurality of receiving systems of an array antenna and converts the signals to I/Q signals, correction value detection means detects a correction value and holds the correction value. Next, if the switching control means 32 selects a reception signal receiving a radio wave from an outside, complex conversion means converts the reception signal to predetermined coordinates on a complex plane for every receiving system, thereby making uniform wave fronts among a plurality of receiving systems to form a beam.

Description

  The present invention relates to a radar apparatus that corrects amplitude / phase errors of received signals from a plurality of receiving systems.

  A radar device having a DBF (Digital Beam Forming) function is used with an array antenna to improve the function and performance of the antenna system, such as multi-beam formation that simultaneously forms multiple beams, and suppression of interfering waves during beam formation. Contribute.

  A radar apparatus having a DBF function includes an array antenna and a signal processing apparatus. DBFs include a full array DBF that directly forms a beam from antenna elements, and a subarray DBF that forms a beam by bundling a plurality of antenna elements and receiving them as a subarray. In any DBF, a reception signal from the array antenna is received by a plurality of transmission / reception modules having signal amplification and frequency conversion functions, and a reception beam is formed in a specified direction in a beam forming unit in the signal processing device.

  Here, the radar apparatus performs wavefront adjustment for matching the amplitude / phase of each transmission / reception module. In this wavefront adjustment, a continuous reference signal is injected into the array antenna, and the received signal of each transmitting / receiving module is input to the signal processing device. In the signal processing device, the received signal from each transmission / reception module is converted into a digital signal and converted into an I / Q signal in the phase detection circuit. Further, the amplitude / phase corresponding to the reception wavefront is obtained from the I / Q signal.

For example, in the radar apparatus described in Patent Document 1, the amplitude / phase when a reference signal is received under a predetermined environmental condition is obtained in advance and stored as reference data. In operation, the reference signal injected again from the array antenna is received to obtain the phase / amplitude, and the correction data is calculated based on the variation from the reference data. Thereby, even if there is a temperature variation of the apparatus, it is possible to align the reception wavefront (Patent Document 1).

  In the radar apparatus described in Patent Document 2, after converting a received signal into a digital signal, one of the digital signals is regarded as a reference signal, and other digital signals are adaptively equivalent by an adaptive filter. Yes. This eliminates the need for complicated adjustment operations such as the collection of I / Q signals and the setting of correction data required in the configuration of Patent Document 1, and allows the wavefront to be automatically adjusted (Patent Document 2).

Japanese Patent No. 3041253 (FIG. 1) Japanese Patent No. 4858522 (FIG. 1)

  The conventional radar device described in Patent Document 1 has a problem that it is difficult to correct an error between reception systems because only a variation from reference data acquired in advance in each reception system is corrected. .

  In addition, the radar apparatus described in Patent Document 2 can quickly correct errors between reception systems. However, since a specific reception system is regarded as a reference signal and phase equivalent is performed, the reception system is There was a problem that the radar device would not function when it failed.

  The present invention has been made to solve the above problems, and can quickly correct the amplitude / phase including fluctuations in the apparatus and errors between the receiving systems, without using a specific receiving system as a reference. An object of the present invention is to provide a radar device that can suppress the influence of failure.

A radar apparatus according to the present invention adjusts an amplitude and a phase between an antenna unit having a plurality of reception systems and reception signals respectively received by the antenna units of the reception system, and forms a beam using the adjusted signal A signal processing unit having a beam forming unit, a reference signal generating unit for generating a reference signal serving as a phase reference, and a received signal received by the antenna unit or the reference signal generating unit as a signal input to the signal processing unit Switching control means for selecting and switching any one of the reference signals generated, wherein the signal processing means phase-detects the signal output by the antenna unit for each reception system, A plurality of phase detection means for outputting an I / Q signal, and the I / Q output by each of the phase detection means when the switching control means selects the reference signal Correction value detecting means for calculating a correction value from the signal, and when the switching control means selects a received signal received by the antenna unit, the received signal is converted into a complex plane for each receiving system using the correction value. A plurality of complex conversion means for converting the reception system to the same phase and outputting the same by converting into the predetermined coordinates above, and a beam forming means for forming a beam using the output of the complex conversion means.

  According to the present invention, the wavefront adjustment between the reception systems in the array antenna can be quickly performed, and the stability of the radar apparatus can be improved.

It is a block diagram which shows the function structure of the radar apparatus by Embodiment 1 of this invention. It is a block diagram which shows the structure of the correction value detection circuit by Embodiment 1 of this invention. It is a figure explaining the method of the complex coordinate transformation by Embodiment 1 of this invention. It is a figure explaining the method of the other complex coordinate transformation by Embodiment 1 of this invention. It is a block diagram which shows the structure of the other correction value detection circuit by Embodiment 1 of this invention. It is a block diagram which shows the function structure of the radar apparatus by Embodiment 2 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a radar apparatus 100 according to Embodiment 1 of the present invention. The radar apparatus 100 according to the present invention includes an array antenna 10, a signal processing apparatus 20, a reference signal generator 31, and a reception switching controller 32.
The radar apparatus 100 may include various devices and functions (not shown), but only the part that is the gist of the present invention will be described here.

The array antenna 10 includes a plurality of antenna modules 11-1 to 11-N and transmission / reception modules 12-1 to 12-N connected to the antenna modules 11-1 to 11-N.
As the antenna modules 11-1 to 11-N, there are a full array DBF formed of a single antenna element and a subarray DBF formed of a plurality of antenna elements. There is a difference in the number of receiving systems 30-1 to 30-N and the scale of the apparatus between the full array DBF and the subarray DBF, but the present invention can be applied to either case.

The signals received by the antenna modules 11-1 to 11-N are amplified, band limited, and frequency converted by the transmission / reception modules 12-1 to 12-N, respectively, and then output.
Some functions of the transmission / reception modules 12-1 to 12-N may be separated from the array antenna 10 as a receiving device (not shown).

The signal processing device 20 includes A / D converters 21-1 to 21-N, phase detection circuits 22-1 to 22-N, correction value detection circuits 23-1 to 23-N, and a complex conversion circuit 24-. 1 to 24-N and a beam forming unit 25-1.
The signal processing device 20 converts the analog signal output from each of the transmission / reception modules 12-1 to 12-N into a digital signal in each of the A / D converters 21-1 to 21-N. The signals converted into digital signals are phase-detected by the phase detection circuits 22-1 to 22-N, respectively, and converted into I / Q signals.

  The antenna module 11-1, the transmission / reception module 12-1, the A / D converter 21-1, the phase detection circuit 22-1, the correction value detection circuit 23-1, and the complex conversion circuit 24-1. One receiving system 30-1 is configured, and the radar apparatus of the present embodiment configures N receiving systems (30-1 to 30-N). The beam forming unit 25-1 receives the outputs from the N receiving systems 30-1 to 30 -N and performs beam forming for the radar apparatus 100.

Next, the operation of the radar apparatus 100 will be described.
The reception switching controller 32 selects the operation mode of the array antenna 10 and the signal processing device 20 by outputting a control signal to the array antenna 10 and the signal processing device 20.

  First, the operation in which the correction value detection circuits 23-1 to 23-N of the signal processing device 20 calculate correction values for aligning the mutual amplitude / phase between the reception systems 30-1 to 30-N will be described.

The reception switching controller 32 outputs a control signal for selecting a mode for receiving a reference signal to the array antenna 10 and the signal processing device 20. The antenna modules 11-1 to 11-N of the array antenna 10 that have received this control signal receive the continuous reference signal output from the reference signal generator 31. This reference signal is a pilot signal that is a phase reference in the radar apparatus 100.
The reference signals received by the antenna modules 11-1 to 11-N are sent to the transmission / reception modules 12-1 to 12-N, the A / D converters 21-1 to 21-N, and the phase detection circuits 22-1 to 22-N. And input to the correction value detection circuits 23-1 to 23 -N as I / Q signals.
The correction value detection circuits 23-1 to 23-N obtain correction values from the I / Q signals, and output the calculated correction values to the complex conversion circuits 24-1 to 24-N.
This correction value is used later as a coefficient for aligning the mutual amplitude / phase between the plurality of receiving systems 30-1 to 30-N.

Next, the reception switching controller 32 outputs to the array antenna 10 and the signal processing device 20 a control signal for selecting a mode for receiving the reception signal.
The antenna modules 11-1 to 11-N of the array antenna 10 that have received this control signal receive radio waves coming from outside the radar apparatus 100, and the received signals received are the transmission / reception modules 12-1 to 12-N, The signals are input to the complex conversion circuits 24-1 to 24-N as I / Q signals via the A / D converters 21-1 to 21-N and the phase detection circuits 22-1 to 22-N.
The complex conversion circuits 24-1 to 24-N complex-multiply the I / Q signal at the time of reception signal selection and the correction values output from the correction value detection circuits 23-1 to 23-N, and beam-form the result. To the unit 25-1.
Here, the outputs of the complex conversion circuits 24-1 to 24-N have the same amplitude / phase among the plurality of reception systems 30-1 to 30-N by complex multiplication of the correction values. In the part 25-1, the beam can be formed in a desired state.

Next, detailed operation of each component will be described.
FIG. 2 is a diagram illustrating an example of the configuration of the correction value detection circuits 23-1 to 23-N and the complex conversion circuits 24-1 to 24-N. Since the N receiving systems 30-1 to 30-N have the same configuration, in FIG. 2, one receiving system 30-1 is given as an example among the receiving systems shown in FIG. explain.

In FIG. 2, the correction value detection circuit 23-1 includes a sampling circuit 731, a normalization coefficient calculation circuit 741, and a division circuit 751.
When the mode for receiving the reference signal is selected by the control signal from the reception switching controller 32, the sampling circuit 731 samples the I / Q signal output from the phase detection circuit 22-1 for a predetermined period. An Io / Qo signal including amplitude / phase information of the reference signal is obtained by averaging, and the result is output to the normalization coefficient calculation circuit 741 and the division circuit 751.

The normalization coefficient calculation circuit 741 obtains the normalization coefficient K using the Io / Qo signal.
For example, in the correction value detection circuit 23-1, when the amplitude and the phase are to be corrected simultaneously, the square of the amplitude is set as the normalization coefficient K as shown in the following equation (1).
When it is desired to correct only the phase without changing the amplitude of the received signal, the amplitude value is set as the normalization coefficient K as shown in the equation (2). Here, sqrt (X) represents the square root of X.

The division circuit 751 divides the Io / Qo signal by the normalization coefficient K to obtain a correction value Id / Qd as shown in the following equation (3).
Here, the coefficient A is an arbitrary value, and may be A = 1. The correction value Id / Qd is calculated and updated every time a mode for receiving a reference signal is selected by a control signal output from the reception switching controller 32 at a predetermined timing.

Next, when the mode in which the antenna module 11-1 receives the reception signal is selected by the control signal from the reception switching controller 32, the complex conversion circuit 24-1 has the following equation (4). The I / Q signal output from the phase detection circuit 22-1 and the correction value Id / Qd output from the division circuit 751 are subjected to complex multiplication, and the corrected Ir / Qr signal is supplied to the beam forming unit 25-1. Output.

FIG. 3 shows a state of complex coordinate transformation in the complex transformation circuit 24-1.
The coordinates 801 = (I, Q), which is the I / Q signal of the reference signal, is converted into coordinates 802 = (Ir, Qr) on the I axis on the complex plane.

At this time, the complex conversion circuit 24-1 can convert to arbitrary coordinates on the complex plane. In this case, however, the circuit for obtaining the correction value Id / Qd becomes complicated.
By using the coordinates after coordinate conversion as coordinates on the I axis as in this embodiment, a circuit for obtaining the correction value Id / Qd can be simplified as in the division circuit 751.

FIG. 4 is a diagram for explaining another method of complex coordinate transformation.
As shown in FIG. 4, by setting the coordinate 812 after coordinate conversion as the coordinate on the Q axis, a circuit for obtaining Id / Qd can be simplified in the same manner. In this case, the conversion in the dividing circuit 751 is an expression shown in Expression (5).

As described above, in the radar apparatus 100 according to the present embodiment, the complex coordinate corrected in the plurality of reception systems 30-1 to 30-N receives the reference signal by the reception switching controller 32 by the above configuration. When the mode is selected, correction is performed so that the same point on the complex plane is obtained. When a mode for receiving a reception signal is selected by the reception switching controller 32, a plurality of reception systems 30- are selected. Amplitude / phase can be aligned between 1 and 30-N.

In the present invention, the plurality of receiving systems 30-1 to 30-N constituting the radar apparatus 100 are on the I axis on the complex plane when receiving the reference signal output from the reference signal generator 31 in the radar apparatus 100. Alternatively, since it is converted into virtual reference coordinates on the Q axis, it is not necessary to acquire reference data in advance after stabilizing a predetermined device environment such as temperature and pressure. In addition, the amplitude / phase can be quickly aligned including device fluctuations and errors between receiving systems.

Also, the radar apparatus 100 according to the present embodiment has a plurality of reception systems 30-1 to 30-N without using a specific reception system among the N reception systems 30-1 to 30-N as a reference. Therefore, even if any of the receiving systems fails, beam forming can be continued, and the influence of the failure can be minimized.
Furthermore, when a specific receiving system is used as a reference, it has been necessary to obtain a correction value based on signals of two receiving systems. However, according to the present invention, a correction value is obtained based on a single I / Q signal. Therefore, there is an advantage that variation is reduced.

  The correction value calculated by the configuration shown in FIG. 2 can be calculated by calculation by a CPU or the like, but can be easily realized by a digital circuit such as an FPGA (Field Programmable Gate Array). Therefore, the above correction calculation can be processed in parallel at high speed, and correction values can be calculated and applied between operations. For example, by periodically switching to a reference signal during operation and updating the correction value, the amplitude / phase that varies depending on the temperature and installation environment inside the device can be corrected as needed, and stable performance can be maintained even during long-term operation. be able to.

  Furthermore, by providing a plurality of memory areas for holding the correction values Id / Qd, the operation mode of the radar apparatus can be quickly changed by simultaneously switching the correction values Id / Qd when the operation mode of the antenna system is switched. be able to. For example, when the wavelength of a radio wave radiated / received in space is switched, the amplitude / phase may be shifted between a plurality of receiving systems depending on the wavelength. However, a plurality of correction values Id are obtained by sampling a reference signal with a changed wavelength in advance. / Qd is held. Even when the wavelength is switched during operation, the performance of the apparatus can be maintained by quickly switching the correction value Id / Qd of the apparatus to an optimal value that matches the selected wavelength.

The embodiment of the present invention is not limited to the above. For example, the correction value detection circuit 23-1 shown in FIG. 2 has a feed-forward type configuration, but may have a feedback type configuration as shown in FIG.
In the configuration shown in FIG. 5, the I / Q signal input to the sampling circuit 732 is not the output from the phase detection circuit 22-1 but the If signal output from the decimation / filter circuit 772 via the complex conversion circuit 24-1. / Qf signal is used.
When the mode for receiving the reference signal output from the reference signal generator 31 is selected and sampled by the reception switching controller 32, the complex conversion circuit 24-1 does not perform complex multiplication of the correction values Id / Qd, but the phase detection circuit. The I / Q signal of 22-1 is output as it is, or the correction value is reset to Id = 1 and Qd = 0 and complex multiplication is performed.

When the reception switching controller 32 selects the reception signals of the antenna modules 11-1 to 11-N, the If / Qf signal that is the output of the thinning / filter circuit 772 of the complex conversion circuit 24-1 is used as the subsequent stage. To the beam forming unit 25-1.
The functions and operations of the sampling circuit 732, the normalization coefficient calculation circuit 742, the division circuit 752, and the complex conversion circuit 24-1 are the same as in the case of FIG.
In the configuration shown in FIG. 5, since data necessary for the sampling circuit 732 is thinned out by the thinning / filter circuit 772 and input with unnecessary noise removed by the filter, a more accurate Io / Qo signal is obtained. There is an advantage that you can get.

Embodiment 2. FIG.
The present invention is particularly effective in a DBF system having a large number of reception systems as in the first embodiment, but is not limited to DBF but can be applied to other forms.
FIG. 6 is a block diagram showing a functional configuration of the radar apparatus 101 according to the second embodiment.
In the radar apparatus 101 shown in FIG. 6, the antenna modules 41-1 to 41-N in the array antenna 40 are antenna output for angle measurement used for phase comparison monopulse angle measurement, for example.
In this case, the transmission / reception modules 42-1 to 42-N, the A / D converters 51-1 to 51-N, and the phase detection circuits 52-1 to 52- constituting the plurality of reception systems 60-1 to 60-N. The functions and operations of N, correction value detection circuits 53-1 to 53-N, and complex conversion circuits 54-1 to 54-N are the same as those in FIG.

In the radar apparatus 101 according to the present embodiment, for example, the reception system 60-1 and the reception system 60-2 include angle measurement information in the azimuth or elevation direction, and the complex conversion circuit 54-1 and the complex conversion circuit 54-2. The output is output to the angle measurement calculation circuit 55-2.
The angle measurement calculation circuit 55-2 can calculate angle measurement data based on the outputs of the complex conversion circuit 54-1 and the complex conversion circuit 54-2, and can output the angle measurement data to a subsequent signal processing circuit (not shown).
In FIG. 6, the reception system 60-N is the main beam reception signal, and the output of the complex conversion circuit 54-N can be output as it is as the main beam. In addition to the configuration of FIG. 6, the sum of a plurality of reception systems may be configured as the main beam.

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

  The present invention can be used for radar devices and communication devices used for airplanes and ships.

10, 40 Array antenna, 20, 50 Signal processing device, 31, 61 Reference signal generator, 32, 62 Reception switching controller, 100, 101 Radar device, 11-1 to 11-N, 41-1 to 41-N Antenna module, 12-1 to 12-N, 42-1 to 42-N transceiver module, 21-1 to 21-N, 51-1 to 51-N A / D converter, 22-1 to 22-N, 52-1 to 52-N phase detection circuit, 23-1 to 23-N, 53-1 to 53-N correction value detection circuit, 24-1 to 24-N, 54-1 to 54-N complex conversion circuit, 25-1, 55-1 Beam forming unit, 30-1 to 30-N, 60-1 to 60-N reception system, 731, 732 sampling circuit, 741, 742 normalization coefficient calculation circuit, 751, 752 division circuit, 772 Decimation / filter circuit, 801, 811 , 802, 812 coordinates after complex coordinate transformation, 55-2 goniometric calculation circuit.

Claims (6)

An antenna unit having a plurality of receiving systems;
Signal processing means having beam forming means for adjusting the amplitude and phase between the received signals respectively received by the antenna section of the receiving system and forming a beam using the adjusted signal;
A reference signal generating means for generating a reference signal as a phase reference;
A switching control means for selecting and switching either a received signal received by the antenna unit or a reference signal generated by the reference signal generating means as a signal input by the signal processing means,
The signal processing means includes
A plurality of phase detection means for phase-detecting a signal output from the antenna unit for each reception system and outputting an I / Q signal;
Correction value detection means for calculating a correction value from the I / Q signal output by each of the phase detection means when the switching control means selects the reference signal;
When the switching control means selects a reception signal received at the antenna unit, the reception signal is converted into predetermined coordinates on a complex plane for each reception system using the correction value, thereby receiving the reception signal. A plurality of complex conversion means for aligning the phases between the systems and outputting them;
A radar apparatus comprising: beam forming means for forming a beam using the output of the complex conversion means. The correction value detecting means includes
Sampling means for sampling the I / Q signal when the reference signal is received;
Normalization coefficient calculation means for obtaining a normalization coefficient from the I / Q signal output from the sampling means;
2. A division means for dividing the I / Q signal output from the sampling means by the normalization coefficient output from the normalization coefficient calculation means to obtain the correction value. The radar apparatus described. The radar apparatus according to claim 1, wherein the complex conversion means converts the coordinates on the I axis or the Q axis on the complex plane for each reception system. The switching control means performs an operation of selecting the reference signal at a predetermined timing,
The radar apparatus according to claim 1, wherein the correction value detection unit calculates and updates the correction value at a timing when the reference signal is selected. 2. The correction value detection unit holds a plurality of the correction values for a plurality of operation modes, and switches to the correction value corresponding to the operation mode when the operation mode is switched. Radar equipment. An antenna unit having a plurality of receiving systems;
A reference signal generating means for generating a reference signal;
A switching control means for selecting a signal input to the phase detection means, either the reception signal received by the antenna unit or the reference signal;
A plurality of phase detection means for phase-detecting a signal output from the antenna unit and outputting the signal as an I / Q signal;
A plurality of correction value detection means for obtaining and holding a correction value from the I / Q signal when the reference signal is received;
A plurality of complex transforming means for outputting a uniform wavefront between the plurality of receiving systems by converting the correction value detected by the correction value detecting means to a predetermined complex coordinate for each receiving system, and
A radar device comprising angle measuring means for obtaining angle measurement information from the output of the complex conversion means.

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