Magnetron radar, signal processing method, and signal processing program

Abstract

The present invention performs coherent processing with a simple configuration. This magnetron radar comprises: a transmission wave generator that generates a transmission wave; an antenna that is used to transmit the transmission wave and receive a reception wave; a circulator that is connected to the transmission wave generator and the antenna; a phase-locked loop oscillator that outputs an oscillation signal of a prescribed frequency; and a mixer that multiplies the oscillation signal and a reception signal based on the reception wave which is received by the antenna and which is output from a first terminal of the circulator, and that multiplies the oscillation signal and a transmission signal based on a main bang signal, which is the transmission wave leaking from the first terminal.

Description

Magnetron Radar, Signal Processing Method, and Signal Processing Program

[0001] The present disclosure relates to a magnetron radar, a signal processing method, and a signal processing program.

[0002] Conventionally, a magnetron radar has been proposed that corrects the phase of a received signal based on the phase of a transmitted signal and performs coherent processing such as calculating the Doppler speed of a target and coherent integration processing using the corrected received signal.

[0003] For example, Patent Document 1 (Japanese Patent Laid-Open No. 11-352218) discloses a coherent-on-receive receiver in a magnetron pulsed Doppler radar device as follows. That is, the coherent-on-receive receiver includes a directional coupler for detecting a transmission pulse, and a switch that receives the transmission pulse signal extracted by the directional coupler and the received signal from the circulator receive arm, and switches between them and outputs them to a subsequent circuit according to a switching control signal.

[0004] Japanese Patent Laid-Open No. 11-352218

[0005] Beyond the technology described in Patent Document 1, a technology capable of performing coherent processing with a simple configuration is desired.

[0006] The present disclosure has been made to solve the above problems, and an object thereof is to provide a magnetron radar, a signal processing method, and a signal processing program capable of performing coherent processing with a simple configuration.

[0007] (1) The magnetron radar of the present disclosure includes a transmission wave generator that generates a transmission wave, an antenna used for transmitting the transmission wave and receiving a reception wave, a circulator connected to the transmission wave generator and the antenna, a phase-locked loop oscillator that outputs an oscillation signal having a predetermined frequency, and a mixer that multiplies a reception signal based on the reception wave received by the antenna and output from a first terminal of the circulator and the oscillation signal, and multiplies a transmission signal based on a main bang signal that is the transmission wave leaking from the first terminal and the oscillation signal.

[0008] Thus, by including a mixer that multiplies the oscillation signal of the phase-locked loop oscillator with the received signal, and also multiplies the oscillation signal of the phase-locked loop oscillator with the main bang signal, it is possible to generate a multiplicative signal of the oscillation signal and the main bang signal with stable phase. Therefore, more accurate initial phase information of the transmitted wave can be obtained from the generated multiplicative signal. As a result, processing can be performed, for example, to cancel the initial phase of the received wave based on the initial phase of the transmitted wave. Furthermore, by using the main bang signal leaking from the circulator, initial phase information of the transmitted wave can be obtained with a smaller circuit size compared to a configuration that uses the transmitted wave extracted using, for example, a directional coupler. Therefore, coherent processing can be performed with a simple configuration.

[0009] (2) In the above (1), the mixer may multiply the transmitted signal and the oscillation signal during the transmission period when the transmitted wave is output from the antenna, and multiply the received signal and the oscillation signal during the reception period when the received wave is received by the antenna.

[0010] With this configuration, the multiplication of the transmitted signal and the oscillation signal, and the multiplication of the received signal and the oscillation signal can be performed in time division using a common mixer, thus enabling frequency conversion of the transmitted and received signals with a simple configuration.

[0011] (3) In (1) or (2) above, the magnetron radar may further include a signal processing unit that acquires phase information of the transmitted wave from a first signal based on a signal generated by multiplying the transmitted signal and the oscillation signal by the mixer, and performs a correction process to correct the phase of a second signal based on a signal generated by multiplying the received signal and the oscillation signal by the mixer using the acquired phase information.

[0012] In this configuration, by acquiring phase information of the transmitted wave from the first signal and correcting the phase of the second signal using the phase information, it is possible to generate a second signal in which the initial phase of the transmitted wave is canceled, and thus coherent processing can be performed using the generated second signal.

[0013] (4) In (3) above, the signal processing unit may acquire the phase information and perform the correction processing for each sweep, and perform coherent processing using the second signal after the correction processing.

[0014] This configuration makes it possible to generate a second signal in which the initial phase of the transmitted wave, which fluctuates randomly with each sweep, is canceled out.

[0015] (5) In (4) above, the signal processing unit may perform the coherent processing using the multiple second signals after the correction processing, each corresponding to a multiple sweep.

[0016] This configuration allows for, for example, the calculation of the Doppler velocity of a target and the improvement of the signal-to-noise ratio of the second signal.

[0017] (6) In (5) above, the signal processing unit may perform the coherent processing using the plurality of second signals after the correction processing, which correspond to each of the plurality of transmitted waves transmitted within a predetermined angular range.

[0018] With this configuration, for example, coherent processing can be performed using multiple second signals based on multiple received waves, including reflected waves from a single target, thereby improving the detection accuracy of the target.

[0019] (7) In any of (3) to (6) above, the signal processing unit may determine whether the signal output from the mixer is a multiplication signal of the transmission signal and the oscillation signal, or a multiplication signal of the reception signal and the oscillation signal.

[0020] With this configuration, a common mixer can be used to perform multiplication of the transmitted signal and the oscillator signal, and multiplication of the received signal and the oscillator signal, while simultaneously allowing the subsequent stage of the mixer to identify the multiplied signal output from the mixer.

[0021] (8) In the above (7), the signal processing unit may determine the multiplying signal based on the elapsed time from the timing when the transmitted wave was output from the antenna.

[0022] This configuration allows for more accurate determination of the multiplication signal depending on whether it is the transmission period of the transmitted wave or the reception period of the received wave.

[0023] (9) In any of (4) to (8) above, an echo image may be generated based on the second signal after the coherent processing.

[0024] This configuration allows for the display of, for example, the Doppler velocity of a target and an echo image that shows the target's more precise location.

[0025] (10) In any of (1) to (9) above, the magnetron radar may further include a receiving circuit connected to the first terminal, the receiving circuit receiving the received wave from the circulator and generating the received signal, and receiving the main bank signal from the circulator and generating the transmitted signal.

[0026] With this configuration, both the received signal and the transmitted signal can be generated using a common receiving circuit, allowing for the generation of both signals with a simple configuration.

[0027] (11) In the above (10), the receiving circuit may include a limiter circuit that limits the amplitude of the received wave and the main bank signal, and an amplifier that amplifies the signal that passes through the limiter circuit.

[0028] With this configuration, the received and transmitted signals can be generated using a common limiter circuit and a common amplifier, allowing for the generation of signals supplied to the mixer with a simple configuration. Although the amplitude of the main bank signal may saturate in the limiter circuit, it is possible to generate a transmitted signal that includes information about the phase component of the main bank signal, thus allowing for the acquisition of initial phase information of the transmitted wave from the transmitted signal.

[0029] (12) In any of (1) to (11) above, the circulator may include a second terminal for receiving the transmitted wave from the transmitting wave generator, a third terminal for outputting the transmitted wave to the antenna and receiving the received wave from the antenna which has been reflected by the transmitted wave by a target, and the first terminal for outputting the received wave.

[0030] This configuration allows for the transmission of a transmission wave and the reception of a reception wave using a common antenna, with a simple setup.

[0031] (13) The signal processing method of the present disclosure is a signal processing method in a magnetron radar, the magnetron radar comprising: a transmitting wave generator that generates a transmitting wave; an antenna used for transmitting the transmitting wave and receiving a receiving wave; a circulator connected to the transmitting wave generator and the antenna; a phase-locked loop oscillator that outputs an oscillation signal of a predetermined frequency; and a mixer that multiplies the oscillation signal by a received signal based on the received wave received by the antenna and output from a first terminal of the circulator, and also multiplies the oscillation signal by a transmitting signal based on a main bang signal which is the transmitting wave leaking from the first terminal, the signal processing method obtains phase information of the transmitting wave from a first signal based on a signal generated by the multiplication of the transmitting signal and the oscillation signal by the mixer, and performs a correction process to correct the phase of a second signal based on a signal generated by the multiplication of the receiving signal and the oscillation signal by the mixer using the phase information.

[0032] In this way, by acquiring phase information of the transmitted wave from the first signal and correcting the phase of the second signal using the phase information, a second signal in which the initial phase of the transmitted wave is canceled can be generated, and coherent processing can be performed using the generated second signal. Furthermore, by configuring the magnetron radar to include a mixer that multiplies the oscillation signal of the phase-locked loop oscillator with the received signal, and also multiplies the oscillation signal of the phase-locked loop oscillator with the main bang signal, more accurate initial phase information of the transmitted wave can be obtained from the multiplicative signal of the phase-stable oscillation signal and the main bang signal. In addition, by using the main bang signal leaking from the circulator, initial phase information of the transmitted wave can be obtained with a smaller circuit size compared to a configuration that uses, for example, a transmitted wave extracted using a directional coupler. Therefore, coherent processing can be performed with a simple configuration.

[0033] (14) The signal processing program of the present disclosure is a signal processing program for a magnetron radar, the magnetron radar comprising: a transmitting wave generator that generates a transmitting wave; an antenna used for transmitting the transmitting wave and receiving a receiving wave; a circulator connected to the transmitting wave generator and the antenna; a phase-locked loop oscillator that outputs an oscillation signal of a predetermined frequency; and a mixer that multiplies the oscillation signal by a received signal based on the received wave received by the antenna and output from a first terminal of the circulator, and also multiplies the oscillation signal by a transmitting signal based on a main bang signal which is the transmitting wave leaking from the first terminal, the signal processing program is a program that causes a computer to perform a process of acquiring phase information of the transmitting wave from a first signal based on a signal generated by the multiplication of the transmitting signal and the oscillation signal by the mixer, and a correction process that uses the phase information to correct the phase of a second signal based on a signal generated by the multiplication of the received signal and the oscillation signal by the mixer.

[0034] In this configuration, by acquiring phase information of the transmitted wave from the first signal and correcting the phase of the second signal using the phase information, a second signal with the initial phase of the transmitted wave canceled out can be generated, allowing coherent processing to be performed using the generated second signal. Furthermore, by configuring the magnetron radar to include a mixer that multiplies the oscillation signal of the phase-locked loop oscillator with the received signal, and also multiplies the oscillation signal of the phase-locked loop oscillator with the main bang signal, more accurate initial phase information of the transmitted wave can be obtained from the multiplicative signal of the phase-stable oscillation signal and the main bang signal. In addition, by using the main bang signal leaking from the circulator, initial phase information of the transmitted wave can be obtained with a smaller circuit size compared to a configuration that uses, for example, a transmitted wave extracted using a directional coupler. Therefore, coherent processing can be performed with a simple configuration.

[0035] According to this disclosure, coherent processing can be performed with a simple configuration.

[0036] Figure 1 is a diagram showing the configuration of a magnetron radar according to an embodiment of the present disclosure. Figure 2 is a diagram showing an example of a transmission trigger output by the signal processing unit in the magnetron radar according to an embodiment of the present disclosure. Figure 3 is a diagram showing the phase of the main bang signal leaking from the circulator in the magnetron radar according to an embodiment of the present disclosure. Figure 4 is a diagram showing the configuration of the signal processing unit in the magnetron radar according to an embodiment of the present disclosure. Figure 5 is a diagram showing the phase of the received signal output from the switching unit in the magnetron radar according to an embodiment of the present disclosure. Figure 6 is a diagram showing the phase of the received signal after correction processing by the correction unit in the magnetron radar according to an embodiment of the present disclosure. Figure 7 is a flowchart showing an example of the operation of the magnetron radar according to an embodiment of the present disclosure when generating an echo image.

[0037] Embodiments of this disclosure will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated. Furthermore, at least some of the embodiments described below may be combined in any way.

[0038] [Configuration and Basic Operation] (Magnetron Radar) Figure 1 is a diagram showing the configuration of a magnetron radar according to an embodiment of the present disclosure. Referring to Figure 1, the magnetron radar 101 comprises a magnetron transmitter 10, a receiving circuit 20, a circulator 30, an antenna 40, a mixer 50, a phase-locked loop oscillator 60, and a signal processing unit 70. The receiving circuit 20 includes a limiter circuit 21 and an LNA (Low Noise Amplifier) ​​22. The magnetron transmitter 10 is an example of a transmitting wave generator. The LNA 22 is an example of an amplifier.

[0039] For example, the magnetron radar 101 can be installed on a ship and used as a ship's radar. The magnetron radar 101 may also be used as a weather radar.

[0040] The magnetron radar 101 transmits a transmission wave Tw to the detection target area, which is the area to be monitored, and receives a reception wave Rw that includes the reflected wave of the transmission wave Tw reflected by the target. Based on the received reception wave Rw, the magnetron radar 301 processes an echo image, which indicates the presence or absence of a target in the detection target area and the distance between the magnetron radar 301 and the target, and displays it on a display device (not shown).

[0041] Figure 2 shows an example of a transmission trigger output by the signal processing unit in a magnetron radar according to an embodiment of the present disclosure.

[0042] Referring to Figures 1 and 2, the signal processing unit 70 outputs a pulsed transmission trigger Tg having a predetermined pulse width Pw to the magnetron transmitter 10 at a transmission timing that follows a predetermined repetition period Cy.

[0043] The magnetron transmitter 10 generates a transmission wave Tw. More specifically, the magnetron transmitter 10 outputs a transmission wave Tw in the RF (Radio Frequency) band to the circulator 30 during a transmission period T1 corresponding to the pulse width Pw of the transmission trigger Tg received from the signal processing unit 70.

[0044] The circulator 30 is connected to the magnetron transmitter 10, the receiving circuit 20, and the antenna 40. More specifically, the circulator 30 includes a terminal P1 connected to the receiving circuit 20, a terminal P2 connected to the magnetron transmitter 10, and a terminal P3 connected to the antenna 40. The terminal P1 is an example of a first terminal, the terminal P2 is an example of a second terminal, and the terminal P3 is an example of a third terminal. The terminal P2 is a port that receives the transmission wave Tw from the magnetron transmitter 10. The terminal P3 is a port where the transmission wave Tw to the antenna 40 is output and also receives the received wave Rw from the antenna 40. The terminal P1 is a port where the received wave Rw to the receiving circuit 20 is output.

[0045] During the transmission period T1, the circulator 30 receives the transmission wave Tw from the magnetron transmitter 10 via the terminal P2. The circulator 30 outputs the received transmission wave Tw to the antenna 40 via the terminal P3. Also, during the transmission period T1, a part of the transmission wave Tw leaks from the terminal P1 in the circulator 30 to the receiving circuit 20. Hereinafter, the transmission wave Tw leaking from the terminal P1 is also referred to as the main bang signal Twm.

[0046] The antenna 40 is used for transmitting the transmission wave Tw and receiving the received wave Rw. During the transmission period T1, the antenna 40 transmits the transmission wave Tw received from the circulator 30 to the detection target area. Also, during the reception period T2 following the transmission period T1, the antenna 40 receives the received wave Rw and outputs it to the circulator 30. Hereinafter, the operation from when the transmission wave Tw is transmitted from the antenna 40 until the next transmission wave Tw is transmitted is referred to as "sweep". For example, the antenna 40 rotates so that the azimuth angle of the radio wave transmission and reception direction changes by a predetermined angle for each sweep period Ts including the transmission period T1 and the reception period T2 following the transmission period T1.

[0047] During the reception period T2, the circulator 30 receives the received wave Rw from the antenna 40 via the terminal P2. The circulator 30 outputs the received received wave Rw to the receiving circuit 20 via the terminal P1.

[0048] The receiving circuit 20 is connected to the terminal P1 in the circulator 30. The receiving circuit 20 receives the received wave Rw from the circulator 30 to generate a received signal Rx, and receives the main bang signal Twm from the circulator 30 to generate a transmission signal Tx. More specifically, the receiving circuit 20 receives the received wave Rw from the circulator 30 to generate a received signal Rx during the reception period T2, and receives the main bang signal Twm from the circulator 30 to generate a transmission signal Tx during the transmission period T1.

[0049] In the receiving circuit 20, the limiter circuit 21 limits the amplitudes of the received wave Rw and the main bang signal Twm. The LNA 22 amplifies the passing signal of the limiter circuit 21.

[0050] More specifically, the limiter circuit 21 receives the received wave Rw from the circulator 30 during the reception period T2, and when the level of the received received wave Rw is less than or equal to a predetermined value Vth, maintains the amplitude of the received received wave Rw and outputs it to the LNA 22. On the other hand, when the level of the received received wave Rw is greater than the predetermined value Vth, the limiter circuit 21 clips the received received wave Rw to a level less than or equal to the predetermined value Vth and outputs it to the LNA 22. The LNA 22 amplifies the signal received from the limiter circuit 21 during the reception period T2, and outputs the amplified signal, which is the received signal Rx, to the mixer 50.

[0051] Also, the limiter circuit 21 receives the main bang signal Twm from the circulator 30 during the transmission period T1, and when the level of the received main bang signal Twm is less than or equal to a predetermined value Vth, maintains the amplitude of the received main bang signal Twm and outputs it to the LNA 22. On the other hand, when the level of the received main bang signal Twm is greater than the predetermined value Vth, the limiter circuit 21 clips the received main bang signal Twm to a level less than or equal to the predetermined value Vth and outputs it to the LNA 22. The LNA 22 amplifies the signal received from the limiter circuit 21 during the transmission period T1, and outputs the amplified signal, which is the transmission signal Tx, to the mixer 50. That is, the received signal Rx and the transmission signal Tx are generated in a common circuit and output to the mixer 50.

[0052] The phase-locked loop oscillator 60 outputs an oscillation signal Sosc at a predetermined frequency. For example, the phase-locked loop oscillator 60 outputs an oscillation signal Sosc at 9 GHz to the mixer 50. More specifically, the phase-locked loop oscillator 60 includes a crystal oscillator, a VCO (Voltage-Controlled Oscillator), a frequency divider, a loop filter, and a phase comparator. The frequency divider is provided between the output of the VCO and the input of the phase comparator, and outputs a signal obtained by dividing the output signal of the VCO by a predetermined frequency to the phase comparator. The crystal oscillator provides an oscillation signal Scry at 100 MHz, for example, to the phase comparator as a reference signal. The phase comparator compares the phase of the oscillation signal Scry received from the crystal oscillator with the phase of the signal received from the frequency divider, and outputs a phase difference signal indicating the comparison result to the loop filter. The loop filter outputs a signal as the control voltage for the VCO, which is a signal obtained by attenuating the frequency components of the phase difference signal received from the phase comparator that are above a predetermined frequency. The VCO generates an oscillation signal Sosc with a frequency corresponding to the level of the control voltage received from the loop filter, for example, and outputs the generated oscillation signal Sosc to the mixer 50. As a result, the phase-locked loop oscillator 60 can output an oscillation signal Sosc with a stable phase to the mixer 50.

[0053] Mixer 50 multiplies the received signal Rx based on the received wave Rw with the oscillation signal Sosc, and also multiplies the transmitted signal Tx based on the main bank signal Twm with the oscillation signal Sosc.

[0054] More specifically, during the reception period T2, the mixer 50 generates a received signal Rif in the IF (Intermediate Frequency) band by multiplying the received signal Rx and the oscillation signal Sosc, and outputs it to the signal processing unit 70. The received signal Rif is the product of the received signal Rx and the oscillation signal Sosc.

[0055] Furthermore, during the transmission period T1, the mixer 50 generates an IF band transmission signal Tif by multiplying the transmission signal Tx and the oscillation signal Sosc, and outputs it to the signal processing unit 70. The transmission signal Tif is a multiplicative signal of the transmission signal Tx and the oscillation signal Sosc.

[0056] The signal processing unit 70 obtains phase information of the transmitted wave Tw from the signal based on the transmitted signal Tif, which is generated by multiplying the transmitted signal Tx and the oscillation signal Sosc by the mixer 50, and uses the obtained phase information to perform a correction process to correct the phase of the signal based on the received signal Rif, which is generated by multiplying the received signal Rx and the oscillation signal Sosc by the mixer 50.

[0057] Figure 3 is a diagram showing the phase of the main bang signal leaking from the circulator in a magnetron radar according to an embodiment of the present disclosure. In Figure 3, the horizontal axis is time and the vertical axis is phase (Degree). The solid line in Figure 3 shows the phase of the main bang signal Twm leaking from the circulator during the transmission period T1 of the sweep period Ts1. The dashed line in Figure 3 shows the phase of the main bang signal Twm leaking from the circulator during the transmission period T1 of the sweep period Ts2 following the sweep period Ts1. The dashed line in Figure 3 shows the phase of the main bang signal Twm leaking from the circulator during the transmission period T1 of the sweep period Ts3 following the sweep period Ts2.

[0058] Referring to Figure 3, the transmitted wave Tw output from the magnetron transmitter 10 and the main bank signal Twm leaking from the circulator 30 have random initial phases. Since the received wave Rw is affected by the initial phase of the transmitted wave Tw, it is difficult to perform coherent processing using a signal based on the received wave Rw. Therefore, the signal processing unit 70 corrects the phase of the signal based on the received signal Rif and performs coherent processing using the corrected signal. The details of the correction process will be explained below.

[0059] (Correction Processing) Figure 4 is a diagram showing the configuration of the signal processing unit in a magnetron radar according to an embodiment of the present disclosure. Referring to Figure 4, the signal processing unit 70 includes a transmission control unit 71, an ADC (Analog-to-Digital Converter) 72, mixers 73A and 73B, a switching unit 74, a calculation unit 75, a correction unit 76, a generation unit 77, and a storage unit 78. Some or all of the switching unit 74, the calculation unit 75, the correction unit 76, and the generation unit 77 are implemented by a processing circuit (Circuitry) including one or more processors, for example. The storage unit 78 is, for example, a non-volatile memory included in the above-mentioned processing circuit.

[0060] The transmission control unit 71 outputs a transmission trigger Tg to the magnetron transmitter 10 and the switching unit 74.

[0061] The ADC 72 digitally converts the signal received from the mixer 50 and outputs it to mixers 73A and 73B. More specifically, during the transmission period T1, the ADC 72 receives the transmission signal Tif from the mixer 50, digitally converts the received transmission signal Tif to generate a digital transmission signal Dt, and outputs it to mixers 73A and 73B. Also, during the reception period T2, the ADC 72 receives the reception signal Rif from the mixer 50, digitally converts the received reception signal Rif to generate a digital reception signal Dr, and outputs it to mixers 73A and 73B.

[0062] Mixer 73A multiplies the digital signal received from ADC 72 with the local signal Lc received from a local oscillator (not shown). More specifically, during the transmission period T1, mixer 73A receives the digital transmission signal Dt from ADC 72, multiplies the received digital transmission signal Dt by the local signal Lc to generate the digital transmission signal Dt_I, and outputs it to the switching unit 74. Also, during the reception period T2, mixer 73A receives the digital reception signal Dr from ADC 72, multiplies the received digital reception signal Dr by the local signal Lc to generate the digital reception signal Dr_I, and outputs it to the switching unit 74.

[0063] Mixer 73B multiplies the digital signal received from ADC 72 with a local signal Lc_90, which is a local signal Lc output from a local oscillator (not shown) with a 90° phase difference applied to it. More specifically, during the transmission period T1, mixer 73B receives a digital transmission signal Dt from ADC 72, multiplies the received digital transmission signal Dt by the local signal Lc_90 to generate a digital transmission signal Dt_Q, and outputs it to the switching unit 74. Also, during the reception period T2, mixer 73B receives a digital reception signal Dr from ADC 72, multiplies the received digital reception signal Dr by the local signal Lc_90 to generate a digital reception signal Dr_Q, and outputs it to the switching unit 74.

[0064] The switching unit 74 switches the output destination of the signals received from mixers 73A and 73B between the calculation unit 75 and the correction unit 76.

[0065] For example, the switching unit 74 determines whether the signal output from the mixer 50 is the transmission signal Tif or the reception signal Rif based on the elapsed time since the transmission wave Tw was output from the antenna 40. The switching unit 74 then outputs the digital transmission signals Dt_I and Dt_Q based on the transmission signal Tif to the calculation unit 75, and the digital reception signals Dr_I and Dr_Q based on the reception signal Rif to the correction unit 76.

[0066] More specifically, the switching unit 74 determines the transmission period T1 and the reception period T2 based on the transmission trigger Tg received from the transmission control unit 71.

[0067] The switching unit 74 determines that the signals received from mixers 73A and 73B during the transmission period T1 are digital transmission signals Dt_I and Dt_Q. The switching unit 74 then outputs a transmission signal Dt_IQ, which is a complex signal with digital transmission signal Dt_I as the real part and digital transmission signal Dt_Q as the imaginary part, to the calculation unit 75. Transmission signal Dt_IQ is an example of a first signal.

[0068] Furthermore, the switching unit 74 determines that the signals received from mixers 73A and 73B during the reception period T2 are digital received signals Dr_I and Dr_Q. The switching unit 74 then outputs a received signal Dr_IQ, which is a complex signal with the digital received signal Dr_I as the real part and the digital received signal Dr_Q as the imaginary part, to the correction unit 76. The received signal Dr_IQ is an example of a second signal.

[0069] Figure 5 shows the phase of the received signal output from the switching unit in a magnetron radar according to an embodiment of the present disclosure. In Figure 5, the horizontal axis is time, and the vertical axis is phase (Degree). The solid line in Figure 5 shows the phase of the received signal Dr_IQ based on the received wave Rw received in sweep period Ts1. The dashed line in Figure 5 shows the phase of the received signal Dr_IQ based on the received wave Rw received in sweep period Ts2 following sweep period Ts1. The dashed line in Figure 5 shows the phase of the received signal Dr_IQ based on the received wave Rw received in sweep period Ts3 following sweep period Ts2. Referring to Figure 5, since the received signal Dr_IQ is affected by the initial phase of the transmitted wave Tw as described above, it is difficult to perform coherent processing using the received signal Dr_IQ.

[0070] The calculation unit 75 performs various calculations on the transmission signal Dt_IQ received from the switching unit 74. For example, as part of the calculation process, the calculation unit 75 receives the transmission signal Dt_IQ from the switching unit 74 during the transmission period T1 and performs an extraction process to extract the transmission signal Dt_IQ received during a specific period within the transmission period T1. More specifically, the calculation unit 75 extracts the transmission signal Dt_IQ received from the transmission signal Dt_IQ output from the switching unit 74 during a target period between timing tm1, which is a predetermined time after the start of the transmission period T1, and timing tm2, which is a predetermined time after timing tm1. This makes it possible to extract the transmission signal Dt_IQ based on a transmission wave Tw with stable amplitude and phase.

[0071] Next, the arithmetic unit 75 performs an averaging process as part of its calculations, which averages the phase of the transmitted signal Dt_IQ extracted in the extraction process. This reduces the noise in the transmitted signal Dt_IQ.

[0072] Next, the calculation unit 75 performs a normalization process to normalize the transmitted signal Dt_IQ after the averaging process so that its amplitude becomes 1.

[0073] The calculation unit 75 generates the complex conjugate signal DtC of the transmission signal Dt_IQ after calculation processing. The complex conjugate signal DtC is an example of phase information of the transmission wave Tw. The calculation unit 75 outputs the generated complex conjugate signal DtC to the correction unit 76. The calculation unit 75 also outputs the transmission signal Dt_IQ received from the switching unit 74 to the generation unit 77.

[0074] The correction unit 76 performs a correction process to correct the phase of the received signal Dr_IQ received from the switching unit 74 using the complex conjugate signal DtC received from the calculation unit 75. More specifically, the correction unit 76 generates the received signal Dr_IQm, which is the received signal Dr_IQ after the correction process, by multiplying the received signal Dr_IQ by the complex conjugate signal DtC.

[0075] For example, the correction unit 76 performs phase information acquisition and correction processing for each sweep. More specifically, for each sweep period Ts, the correction unit 76 generates a received signal Dr_IQm by multiplying the received signal Dr_IQ, which is based on the received wave Rw received during the reception period T2 of the sweep period Ts, by the complex conjugate signal DtC, which is based on the transmitted wave Tw transmitted during the transmission period T1 of the sweep period Ts.

[0076] Figure 6 shows the phase of the received signal after correction processing by the correction unit in the magnetron radar according to an embodiment of the present disclosure. In Figure 6, the horizontal axis is time and the vertical axis is phase (Degree). The solid line in Figure 6 shows the phase of the received signal Dr_IQm based on the received wave Rw received in sweep period Ts1. The dashed line in Figure 6 shows the phase of the received signal Dr_IQm based on the received wave Rw received in the sweep period Ts2 following sweep period Ts1. The dashed line in Figure 6 shows the phase of the received signal Dr_IQm based on the received wave Rw received in sweep period Ts3 following sweep period Ts2. Referring to Figure 6, the initial phase of the transmitted wave Tw is canceled in the received signal Dr_IQm. The correction unit 76 outputs the generated received signal Dr_IQm to the generation unit 77.

[0077] The generation unit 77 stores the received signal Dr_IQm received from the correction unit 76 in the storage unit 78.

[0078] The generation unit 77 performs coherent processing using the received signal Dr_IQm. For example, the generation unit 77 performs coherent processing using multiple received signals Dr_IQm corresponding to multiple sweeps. Alternatively, for example, the generation unit 77 performs coherent processing using multiple received signals Dr_IQm corresponding to multiple transmitted waves Tw transmitted within a predetermined angular range. As an example, the generation unit 77 performs coherent processing using 16 received signals Dr_IQm in the storage unit 78, each corresponding to a transmitted wave Tw transmitted during 16 consecutive sweep periods Ts.

[0079] For example, the generation unit 77 performs a Doppler process as a coherent process to calculate the Doppler velocity of the target using the 16 received signals Dr_IQm. Alternatively, the generation unit 77 performs a coherent integration process as a coherent process to generate an added signal Sum, which is the sum of the 16 received signals Dr_IQm. This makes it possible to generate an added signal Sum whose signal-to-noise ratio is 16 times that of the received signals Dr_IQm.

[0080] The generation unit 77 generates an echo image based on the received signal Dr_IQm after coherent processing, and then performs a process to display the generated echo image. More specifically, the generation unit 77 calculates the position of the ship equipped with the magnetron radar 101 based on the transmitted signal Dt_IQ received from the calculation unit 75. The generation unit 77 also calculates the position of the target based on the generated sum signal Sum. The generation unit 77 then generates an echo image showing the position of the ship, the position of the target, and the Doppler velocity. The generation unit 77 then performs a process to display the generated echo image on a display device (not shown). This makes it possible to display an echo image showing the position of the ship equipped with the magnetron radar, the Doppler velocity of the target, and a more accurate position of the target.

[0081] The signal processing unit 70 may also be configured without the switching unit 74. In this case, the signal processing unit 70 performs a correction process to correct the phase of the transmitted signal Dt_IQ and the received signal Dr_IQ together, and then performs coherent processing using the corrected transmitted signal Dt_IQ and the received signal Dr_IQ. More specifically, the mixers 73A and 73B output the signals obtained by multiplication using the local signal Lc to the calculation unit 75 and the correction unit 76. The calculation unit 75 generates a complex conjugate signal DtC by performing the various calculation processes described above on the signals received from the mixers 73A and 73B during the transmission period T1, and outputs the generated complex conjugate signal DtC to the correction unit 76. Regardless of whether it is the transmission period T1 or the reception period T2, the correction unit 76 multiplies the signals received from the mixers 73A and 73B by the complex conjugate signal DtC received from the calculation unit 75, and outputs the multiplied signal to the generation unit 77. The generation unit 77 performs coherent processing using the multiplication signal received from the correction unit 76.

[0082] [Operation Flow] The magnetron radar according to the embodiment of this disclosure includes a computer including memory, and a processor such as a CPU in the computer reads and executes a program from the memory that includes some or all of the steps in the following flowchart. The program for this device can be installed externally. The program for this device is stored on a recording medium or distributed via a communication line.

[0083] Figure 7 is a flowchart showing an example of the operation of a magnetron radar according to an embodiment of the present disclosure when generating an echo image. For example, the magnetron radar 101 performs the process shown in Figure 7 for each sweep period Ts.

[0084] Referring to Figure 7, first, the signal processing unit 70 in the magnetron radar 101 determines that the signals received from mixers 73A and 73B during the transmission period T1 are digital transmission signals Dt_I and Dt_Q, and generates a transmission signal Dt_IQ with the digital transmission signal Dt_I as the real part and the digital transmission signal Dt_Q as the imaginary part (step S11).

[0085] Next, the signal processing unit 70 performs various calculations on the transmitted signal Dt_IQ. More specifically, the signal processing unit 70 performs extraction, averaging, and normalization as calculations (step S12).

[0086] Next, the signal processing unit 70 generates the complex conjugate signal DtC of the transmission signal Dt_IQ after the calculation processing (step S13).

[0087] Next, the signal processing unit 70 determines that the signals received from mixers 73A and 73B during the reception period T2 are digital received signals Dr_I and Dr_Q, and generates a received signal Dr_IQ with the digital received signal Dr_I as the real part and the digital received signal Dr_Q as the imaginary part (step S14).

[0088] Next, the signal processing unit 70 performs a correction process to correct the phase of the received signal Dr_IQ using the complex conjugate signal DtC. More specifically, the signal processing unit 70 generates the received signal Dr_IQm by multiplying the received signal Dr_IQ by the complex conjugate signal DtC (step S15).

[0089] Next, the signal processing unit 70 performs coherent processing using the received signal Dr_IQm. More specifically, the signal processing unit 70 performs Doppler processing and coherent integration processing as coherent processing (step S16).

[0090] Next, the signal processing unit 70 calculates the position of the target based on the summation signal Sum generated by coherent integration and generates an echo image showing the position of the ship, the position of the target, and the Doppler velocity (step S17).

[0091] Next, the signal processing unit 70 performs a process to display the echo image on a display device (not shown) (step S18).

[0092] The embodiments described above should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. term

[0093] Not all objectives or effects / benefits can necessarily be achieved in accordance with any particular embodiment described herein. Therefore, for example, a person skilled in the art will realize that a particular embodiment may be configured to achieve or optimize one or more effects / benefits taught herein, without necessarily achieving other objectives or effects / benefits taught or suggested herein.

[0094] All processes described herein can be fully automated and implemented by software code modules executed by a computing system including one or more computers or processors. The code modules can be stored in any type of non-temporary computer-readable medium or other computer storage device. Some or all of these methods can be implemented in dedicated computer hardware.

[0095] It will be apparent from this disclosure that there are many other variations not described herein. For example, depending on the embodiment, any particular operation, event, or function of any of the algorithms described herein may be performed in different sequences, and may be added, merged, or excluded entirely (e.g., not all described actions or events are necessary for the execution of the algorithm). Furthermore, in certain embodiments, the operations or events may be performed in parallel rather than sequentially, for example, through multithreading, interrupt handling, or via multiple processors or processor cores, or on other parallel architectures. In addition, different tasks or processes may also be performed by different machines and / or computing systems that can work together.

[0096] Various exemplary logic blocks and modules described in relation to the embodiments disclosed herein can be implemented or executed by a machine such as a processor. The processor may be a microprocessor, but alternatively, the processor may be a controller, a microcontroller, or a state machine, or a combination thereof. The processor may include electrical circuits configured to process computer-executable instructions. In another embodiment, the processor may include an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable device that performs logic operations without processing computer-executable instructions. The processor may also be implemented as a combination of computing devices, for example, a combination of a digital signal processor (digital signal processing device) and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. Although the description herein mainly concerns digital technology, the processor may also include mainly analog elements. For example, some or all of the signal processing algorithms described herein may be implemented by analog circuits or mixed analog and digital circuits. The computing environment may include, but is not limited to, any type of computer system based on a microprocessor, mainframe computer, digital signal processor, portable computing device, device controller, or in-device computing engine.

[0097] Unless otherwise specified, conditional language such as “can,” “could,” “will,” or “may” is understood to mean in the context of commonly used expressions to convey that a particular embodiment includes certain features, elements, and / or steps, but other embodiments do not. Thus, such conditional language does not generally mean that features, elements, and / or steps are any way required in one or more embodiments, or that one or more embodiments necessarily include logic for determining whether these features, elements, and / or steps are included in or performed in any particular embodiment.

[0098] Disjunctive language, such as the phrase "at least one of X, Y, and Z," is understood in contexts where it is commonly used to indicate that an item, term, etc., can be any one of X, Y, Z, or any combination thereof, unless otherwise specified (e.g., X, Y, Z). Therefore, such disjunctive language does not generally imply that a particular embodiment requires each of at least one of X, at least one of Y, or at least one of Z, each of which exists.

[0099] Any process description, element, or block in the flowcharts described herein and / or shown in the accompanying drawings should be understood as representing a potentially module, segment, or portion of code containing one or more executable instructions for implementing a particular logical function or element in the process. Alternative embodiments are included within the scope of the embodiments described herein, where elements or functions may be removed, performed in no particular order, substantially simultaneously or in reverse order, depending on the relevant functionality, as will be understood by those skilled in the art.

[0100] Unless otherwise explicitly stated, numerals such as “one” should generally be interpreted as including one or more described items. Thus, phrases such as “one device configured to do…” are intended to include one or more enumerated devices. Such one or more enumerated devices may also be collectively configured to perform the stated citation. For example, “a processor configured to perform A, B and C below” could include a first processor configured to perform A and a second processor configured to perform B and C. In addition, even if an enumeration of a specific number of the introduced embodiments is explicitly listed, a person skilled in the art should interpret such an enumeration as typically meaning at least the number listed (for example, a mere enumeration of “two enumerations” without other modifiers usually means at least two enumerations, or two or more enumerations).

[0101] In general, a person skilled in the art will find that the terms used herein are generally intended to be "non-limiting" terms (for example, the term "including" should be interpreted as "including, but at least," the term "having" should be interpreted as "having at least," and the term "including" should be interpreted as "including, but not limited to, the following").

[0102] For illustrative purposes, the term “horizontal” as used herein is defined as a plane parallel to the floor or surface of the area in which the system described is used, or the plane on which the method described is implemented, regardless of its direction. The term “floor” may be replaced with the terms “ground” or “water surface.” The term “vertical / perpendicular” refers to a direction perpendicular / perpendicular to the defined horizontal line. Terms such as “upper side,” “lower side,” “below,” “up,” “on the side,” “higher,” “lower,” “above,” and “below” are defined in relation to the horizontal plane.

[0103] As used herein, the terms “adhere,” “connect,” “pair,” and other related terms should be interpreted, unless otherwise noted, as including removable, movable, fixed, adjustable, and / or removable connections or linkages. Connections / linkages include direct connections and / or connections having an intermediate structure between the two components described.

[0104] Unless otherwise explicitly stated, the numbers preceded by terms such as “approximately,” “about,” and “substantially,” as used herein, include the enumerated numbers and represent quantities close to the stated quantities that further perform the desired function or achieve the desired result. For example, “approximately,” “about,” and “substantially,” unless otherwise explicitly stated, mean values ​​less than 10% of the stated numbers. Features of embodiments disclosed preceded by terms such as “approximately,” “about,” and “substantially,” as used herein, represent features with some variability that further perform the desired function or achieve the desired result with respect to that feature.

[0105] Many variations and modifications can be made to the embodiments described above, and these elements should be understood as being within other acceptable examples. All such modifications and variations are intended to be included within the scope of this disclosure and are protected by the following claims.

[0106] 10 Magnetron transmitter 20 Receiving circuit 21 Limiter circuit 22 LNA 30 Circulator 40 Antenna 50 Mixer 60 Phase-locked loop oscillator 70 Signal processing unit 71 Transmitting control unit 72 ADC 73A, 73B Mixer 74 Switching unit 75 Calculation unit 76 Correction unit 77 Generation unit 78 Memory unit 101 Magnetron radar Tg Transmitting trigger Cy Repetition period Pw Pulse width T1 Transmitting period T2 Receiving period Ts Sweep period

Claims

1. A magnetron radar comprising: a transmitter wave generator for generating a transmit wave; an antenna used for transmitting the transmit wave and receiving a receive wave; a circulator connected to the transmitter wave generator and the antenna; a phase-locked loop oscillator that outputs an oscillation signal of a predetermined frequency; and a mixer that multiplies the oscillation signal by a received signal based on the received wave received by the antenna and output from a first terminal of the circulator, and also multiplies the oscillation signal by a transmit signal based on the main bang signal, which is the transmit wave leaking from the first terminal.

2. The magnetron radar according to claim 1, wherein the mixer multiplies the transmitted signal and the oscillation signal during the transmission period when the transmitted wave is output from the antenna, and multiplies the received signal and the oscillation signal during the reception period when the received wave is received by the antenna.

3. The magnetron radar according to claim 1, further comprising: a signal processing unit that acquires phase information of the transmitted wave from a first signal based on a signal generated by multiplying the transmitted signal and the oscillation signal by the mixer, and performs a correction process to correct the phase of a second signal based on a signal generated by multiplying the received signal and the oscillation signal by the mixer using the acquired phase information.

4. The magnetron radar according to claim 3, wherein the signal processing unit performs the acquisition of phase information and the correction processing for each sweep, and performs coherent processing using the second signal after the correction processing.

5. The magnetron radar according to claim 4, wherein the signal processing unit performs the coherent processing using the multiple second signals after the correction processing, each corresponding to a multiple sweep.

6. The magnetron radar according to claim 5, wherein the signal processing unit performs the coherent processing using the plurality of second signals after correction processing, each corresponding to a plurality of transmitted waves transmitted within a predetermined angular range.

7. The magnetron radar according to any one of claims 3 to 6, wherein the signal processing unit determines whether the signal output from the mixer is a multiplication signal of the transmission signal and the oscillation signal, or a multiplication signal of the reception signal and the oscillation signal.

8. The magnetron radar according to claim 7, wherein the signal processing unit determines the multiplication signal based on the elapsed time from the timing at which the transmitted wave was output from the antenna.

9. The magnetron radar according to any one of claims 4 to 6, wherein the signal processing unit generates an echo image based on the second signal after coherent processing.

10. The magnetron radar according to claim 1, further comprising a receiving circuit connected to the first terminal, wherein the receiving circuit receives the received wave from the circulator and generates the received signal, and receives the main bang signal from the circulator and generates the transmitted signal.

11. The magnetron radar according to claim 10, wherein the receiving circuit includes a limiter circuit that limits the amplitude of the received wave and the main bang signal, and an amplifier that amplifies the signal passing through the limiter circuit.

12. The magnetron radar according to claim 1, wherein the circulator includes a second terminal for receiving the transmitted wave from the transmitting wave generator, a third terminal for outputting the transmitted wave to the antenna and receiving the received wave from the antenna which is the transmitted wave reflected by a target, and the first terminal for outputting the received wave.

13. A signal processing method in a magnetron radar, wherein the magnetron radar comprises a transmit wave generator that generates a transmit wave, an antenna used for transmitting the transmit wave and receiving a receive wave, a circulator connected to the transmit wave generator and the antenna, a phase-locked loop oscillator that outputs an oscillation signal of a predetermined frequency, and a mixer that multiplies the oscillation signal by a received signal based on the received wave received by the antenna and output from a first terminal of the circulator, and multiplies the oscillation signal by a transmit signal based on the main bung signal which is the transmit wave leaking from the first terminal, wherein the signal processing method acquires phase information of the transmit wave from a first signal based on a signal generated by the multiplication of the transmit signal and the oscillation signal by the mixer, and performs a correction process to correct the phase of a second signal based on a signal generated by the multiplication of the received signal and the oscillation signal by the mixer using the phase information.

14. A signal processing program for a magnetron radar, wherein the magnetron radar comprises a transmit wave generator that generates a transmit wave, an antenna used for transmitting the transmit wave and receiving a receive wave, a circulator connected to the transmit wave generator and the antenna, a phase-locked loop oscillator that outputs an oscillation signal of a predetermined frequency, and a mixer that multiplies the oscillation signal by a received signal based on the received wave received by the antenna and output from a first terminal of the circulator, and multiplies the oscillation signal by a transmit signal based on the main bung signal which is the transmit wave leaking from the first terminal, wherein the signal processing program causes a computer to perform the following: a process of acquiring phase information of the transmit wave from a first signal based on a signal generated by the multiplication of the transmit signal and the oscillation signal by the mixer, and a correction process of correcting the phase of a second signal based on a signal generated by the multiplication of the received signal and the oscillation signal by the mixer using the phase information.

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