JP2012194043A - Radar apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar apparatus that can appropriately separate a plurality of different signals from one another by correlation processing and subject the signals to beam synthesis.SOLUTION: A radar apparatus is provided with a modulated waveform selector 1 that selects, out of a plurality of nonlinear frequency-modulated waveforms that differ in chirp rate between the central part and the edge parts of pulse, a combination of nonlinear frequency-modulated waveforms whose range shift quantities ΔR attributable to a Doppler frequency are equalized, and a frequency modulator 2 generates a plurality of modulated signals by subjecting transmission signals to frequency modulation by using each of the nonlinear frequency-modulated waveforms selected by the modulated waveform selector 1.

Description

  The present invention relates to a radar apparatus that transmits and receives a plurality of different signals by a distributed radar or the like, separates the signals by correlation processing of each signal, and performs signal beam synthesis processing.

In a radar apparatus that transmits and receives a plurality of different signals by a distributed radar or the like, it is necessary to separate a plurality of different signals, and therefore, a cross-correlation characteristic between the plurality of signals is required to be as low as possible.
In addition, in order to perform beam synthesis processing after receiving a plurality of signals, it is required that the range shift amount and the phase shift amount by the Doppler frequency be constant.

Here, code modulation, linear frequency modulation, and the like are known as modulation applied to the transmission wave by the radar apparatus.
For example, the following Non-Patent Document 1 discloses a radar apparatus that performs code modulation. However, in this radar apparatus, the range side lobe level may deteriorate with respect to a target having a Doppler frequency.

The following Patent Document 1 discloses a radar device that performs linear frequency modulation.
In this radar device, the range shift amount due to the Doppler frequency is proportional to the center frequency and the pulse width, and the range shift amount is inversely proportional to the chirp bandwidth, and the center frequency and pulse width or the center frequency By adjusting the chirp bandwidth, waveforms having the same range shift amount are generated.

However, in this radar apparatus, when the center frequencies between signals are different, even if the range shift amount is the same, the phase shift amount is different, so that beam synthesis in the same phase is difficult.
Further, when the center frequencies between the signals are equal, if the range shift amount is equal, the phase shift amount is also equal, and beam synthesis in the same phase can be performed, but the slopes of the respective modulation waveforms are equal.
For this reason, the cross-correlation value between the signals becomes high, and the signals may not be separated by correlation processing.

The following Patent Document 2 discloses a radar device that performs nonlinear frequency modulation.
Since this radar apparatus has a higher degree of freedom in waveform than linear frequency modulation, it is possible to reduce the cross-correlation value.
However, in the nonlinear frequency modulation, the range sidelobe deterioration due to the Doppler frequency and the variation of the range shift amount and the phase shift amount may become significant depending on the shape of the modulation waveform.
Therefore, it is difficult to select a modulation waveform shape when beam synthesis is performed by transmitting and receiving a plurality of signals.

Japanese Patent Laid-Open No. 5-312939 (paragraph number [0007], FIG. 1) JP 2010-243295 A (paragraph number [0014], FIG. 1)

Reducing the Waveform Cross Correlation of MIMO Radar With Space-Time Coding, IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 58, NO.8, AUGUST 2010

  Since the conventional radar apparatus is configured as described above, for example, when using a method of performing linear frequency modulation, if the center frequency between signals is different, even if the range shift amount is the same, the phase shift amount is different. , Beam synthesis cannot be performed. If the center frequencies between the signals are equal, beam synthesis can be performed. However, since the chirp rate between the signals is equal, the cross-correlation value between the signals is high, and the signals are separated by correlation processing. There were problems such as being unable to do so.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a radar apparatus capable of performing beam synthesis by properly separating a plurality of different signals by correlation processing.

  A radar apparatus according to the present invention selects a combination of nonlinear frequency modulation waveforms in which the amount of range shift due to the Doppler frequency is equal from a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and end of a pulse. A selection unit; a frequency modulation unit that generates a plurality of modulation signals by frequency-modulating a transmission signal using each nonlinear frequency modulation waveform selected by the modulation waveform selection unit; and a plurality of units generated by the frequency modulation unit Signal transmission means for radiating the modulated signal of the signal to the space, and signal reception for receiving, as the received signal, a plurality of modulated signals that have been radiated from the signal transmission means to the space and then reflected back to the target existing in the space Means, a plurality of received signals received by the signal receiving means and a plurality of modulated signals generated by the frequency modulating means The correlation process performed with No. is obtained by so providing a beam combining means for adding the peak values of each of the correlation processing result.

  According to the present invention, the modulation waveform selection means for selecting a combination of nonlinear frequency modulation waveforms having the same range shift amount due to the Doppler frequency from among a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and end of the pulse. And frequency modulation means for generating a plurality of modulation signals by frequency-modulating the transmission signal using each nonlinear frequency modulation waveform selected by the modulation waveform selection means, and a plurality of modulations generated by the frequency modulation means A signal transmission unit that radiates a signal to space, and a signal reception unit that receives, as reception signals, a plurality of modulated signals that are radiated from the signal transmission unit to the space and then return to the target existing in the space. The phase of a plurality of received signals received by the signal receiving means and a reference signal which is a plurality of modulated signals generated by the frequency modulating means And the beam combining means for adding the peak values of the respective correlation processing results are provided, so that the plurality of received signals received by the signal receiving means are appropriately processed by the correlation processing with the reference signal. There is an effect that beam synthesis can be performed by separating them.

It is a block diagram which shows the radar apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows range shift amount (DELTA) R of a correlation processing waveform. It is explanatory drawing which shows an example of the correlation process result with equal range shift amount (DELTA) R selected by the modulation waveform selection part. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is explanatory drawing which shows an example of the some nonlinear frequency modulation waveform from which the chirp rate in the center part and edge part of a pulse differs. It is a block diagram which shows the radar apparatus by Embodiment 3 of this invention. It is explanatory drawing which shows the nonlinear frequency modulation waveform represented by the reciprocal number of the function with which the sine function and the linear chirp function were added. It is explanatory drawing which shows an example of the nonlinear frequency modulation waveform with the same range shift amount (DELTA) R selected by the modulation waveform selection part. It is a block diagram which shows the radar apparatus by Embodiment 4 of this invention. It is explanatory drawing which shows the nonlinear frequency modulation waveform represented with the function in which the tan function is normalized by the pulse width and the bandwidth. It is explanatory drawing which shows an example of the nonlinear frequency modulation waveform with the same range shift amount (DELTA) R selected by the modulation waveform selection part. It is a block diagram which shows the radar apparatus by Embodiment 5 of this invention. It is explanatory drawing which shows the nonlinear frequency modulation waveform by which an edge part is represented by the function which added the hyperbola function and the linear chirp function, and a center part is represented by the said linear chirp function. It is explanatory drawing which shows the hyperbola function used in the edge part of the right side of a pulse. It is explanatory drawing which shows the hyperbolic function used in the edge part of the left side of a pulse. It is explanatory drawing which shows an example of the nonlinear frequency modulation waveform with the same range shift amount (DELTA) R selected by the modulation waveform selection part. It is explanatory drawing which shows an example of the nonlinear frequency modulation waveform with the same range shift amount (DELTA) R selected by the modulation waveform selection part.

Embodiment 1 FIG.
1 is a block diagram showing a radar apparatus according to Embodiment 1 of the present invention.
In FIG. 1, the modulation waveform selection unit 1 selects a combination of nonlinear frequency modulation waveforms in which the range shift amount ΔR due to the Doppler frequency is equal from a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and end of the pulse. Perform the process.
That is, the modulation waveform selection unit 1 has the same overall pulse width T ₀ , overall bandwidth B ₀ , central pulse width T, and end pulse width dt, and the central bandwidth B and end bandwidth. A process of selecting a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency is selected from a plurality of nonlinear frequency modulation waveforms having different widths df. The modulation waveform selection unit 1 constitutes a modulation waveform selection unit.
In the example of FIG. 1, since the frequency modulation unit 2 is composed of three frequency modulators 2a, 2b, and 2c, three sets of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency are selected.

The frequency modulation unit 2 is composed of N frequency modulators (N is an integer of 2 or more) (in the example of FIG. 1, it is composed of three frequency modulators 2a, 2b, and 2c). A process of outputting a modulated signal, which is a modulated transmission signal, to the transmission processing unit 3 and the correlation processing unit 7 by frequency-modulating the transmission signal using each nonlinear frequency modulation waveform selected by the waveform selection unit 1 carry out.
The frequency modulators 2a, 2b, 2c of the frequency modulation unit 2 frequency-modulate the transmission signal using the nonlinear frequency modulation waveform selected by the modulation waveform selection unit 1, and transmit the modulated signal, which is the modulated transmission signal, to the transmitter 3a. , 3b, 3c, the correlation processor 7a, and the like.
The frequency modulation unit 2 constitutes frequency modulation means.

The transmission processing unit 3 is composed of N transmitters (N is an integer of 2 or more) (in the example of FIG. 1, it is composed of three transmitters 3a, 3b, and 3c), and a frequency modulation unit 2 is supplied to the transmission array antenna 4 so that the modulation signal is emitted from the transmission array antenna 4 to the space as a transmission RF signal.
The transmitters 3a, 3b, 3c of the transmission processing unit 3 modulate the modulation from the transmission antennas 4a, 4b, 4c by supplying the modulation signals output from the frequency modulators 2a, 2b, 2c to the transmission antennas 4a, 4b, 4c. A process of emitting a signal to the space as a transmission RF signal is performed.

The transmission array antenna 4 is composed of N transmission antennas (N is an integer of 2 or more) (in the example of FIG. 1, it is composed of three transmission antennas 4a, 4b, 4c), and a transmission processing unit. The plurality of modulation signals output from 3 are radiated to the space as transmission RF signals.
The transmission antennas 4a, 4b, and 4c of the transmission array antenna 4 radiate modulated signals output from the transmitters 3a, 3b, and 3c to space as transmission RF signals.
The transmission processing unit 3 and the transmission array antenna 4 constitute signal transmission means.

The receiving array antenna 5 is composed of M receiving antennas (M is an integer of 2 or more) (in the example of FIG. 1, it is composed of three receiving antennas 5a, 5b, 5c), and a transmitting array antenna. After being radiated from 4 to the space, a plurality of RF signals reflected and returned to the target existing in the space are received as reflected RF signals.
The reflected RF signals received by the receiving antennas 5a, 5b, and 5c of the receiving array antenna 5 are signals in which three types of RF signals are combined, and are all the same signal.

The reception processing unit 6 is composed of M receivers (M is an integer of 2 or more) (in the example of FIG. 1, it is composed of three receivers 6a, 6b, 6c), and a receiving array antenna. The process which outputs the some reflected RF signal received by 5 to the correlation process part 7 as a received signal is implemented.
The receivers 6a, 6b, and 6c of the reception processing unit 6 perform processing of outputting the reflected RF signals received by the reception antennas 5a, 5b, and 5c to the correlation processors 7a to 7c, 7d to 7f, and 7g to 7i as reception signals. carry out.
The reception array antenna 5 and the reception processing unit 6 constitute signal reception means.

The correlation processing unit 7 includes N × M units (N and M are integers of 2 or more) (in the example of FIG. 1, the correlation processing unit 7 includes nine correlation processors 7a to 7i). The correlation processing of the plurality of reception signals output from the reception processing unit 6 and the reference signals that are the plurality of modulation signals output from the frequency modulation unit 2 is performed, and the peak value of each correlation processing result is beam-synthesized To the device 8.
The correlation processors 7 a to 7 i of the correlation processing unit 7 perform a correlation process between the received signal and the reference signal, and perform a process of outputting the peak value of the correlation process result to the beam combiner 8.
The beam synthesizer 8 performs a process of obtaining a beam synthesis result by adding a plurality of peak values output from the correlation processors 7a to 7i.
The correlation processing unit 7 and the beam combiner 8 constitute beam combining means.

Next, the operation will be described.
FIG. 2 is an explanatory diagram showing nonlinear frequency modulation waveforms with different chirp rates at the center and end of the pulse.
In the example of FIG. 2, the horizontal axis represents the pulse width normalized at −0.5 to 0.5, and the bandwidth normalized at −0.5 to 0.5 with the transmission frequency as the center. It is shown on the vertical axis.

In FIG. 2, f ₀ is a transmission frequency, T ₀ is a pulse width, and B ₀ is a bandwidth.
Also, t is time, T is the ratio of the pulse width at the pulse center to the entire pulse width T ₀ , B is the ratio of the bandwidth at the pulse center to the entire bandwidth B ₀ , and dt is the pulse width T _0. The ratio of the pulse width at the end of the pulse to the entirety of, and the ratio of the bandwidth at the end of the pulse to the entire df bandwidth B ₀ .

The nonlinear frequency modulation waveform in FIG. 2 is represented by a function f (t) shown in the following equation (1).

The modulation waveform selection unit 1 varies the time t in the function f (t) of the equation (1) by the parameter variation width Δ (i) shown in the following equation (3), so that the center and end of the pulse are changed. A plurality of nonlinear frequency modulation waveforms having different chirp rates are generated.
That is, the overall pulse width T ₀ , the overall bandwidth B ₀ , the central pulse width T and the end pulse width dt are the same, and the central bandwidth B and the end bandwidth df are different. A plurality of nonlinear frequency modulation waveforms are generated.
Here, FIG. 3 is an explanatory diagram showing an example of a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and end of the pulse.

When the modulation waveform selection unit 1 generates a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and end portions of the pulse, the nonlinearity in which the range shift amount ΔR depending on the Doppler frequency is equal among the plurality of nonlinear frequency modulation waveforms. Select a combination of frequency modulation waveforms.
That is, the modulation waveform selection unit 1 displays a correlation processing result between a signal modulated with a certain non-linear frequency modulation waveform and a signal obtained by adding the assumed Doppler frequency to the signal modulated with the non-linear frequency modulation waveform. Then, the range shift amount ΔR at which the correlation processing result reaches a peak is obtained, and the combination of the nonlinear frequency modulation waveforms with the same range shift amount ΔR is selected.
When the correlation waveform selection unit 1 performs correlation processing between the reference signal and the received signal for each nonlinear frequency modulation waveform, the modulation waveform selection unit 1 corresponds to the amplitude that takes the peak value in the correlation processing result related to each nonlinear frequency modulation waveform. The range bin to be identified is specified as the range shift amount ΔR.

FIG. 4 is an explanatory diagram showing the range shift amount ΔR of the correlation processing waveform.
When the Doppler frequency is fd, the range shift amount ΔR is a reference signal that is a transmission signal modulated by a non-linear frequency modulation waveform, and a reception RF signal that is reflected back to a target existing in space. In the result of correlation processing with the signal, the range bin taking the peak value indicates how many bin shifts compared to the case where the Doppler frequency is zero.

When the modulation waveform selection unit 1 specifies the range shift amount ΔR for each nonlinear frequency modulation waveform, a combination of nonlinear frequency modulation waveforms in which the range shift amount ΔR due to the Doppler frequency is equal is selected from the plurality of nonlinear frequency modulation waveforms. select.
In the example of FIG. 1, since the frequency modulation unit 2 is composed of three frequency modulators 2a, 2b, and 2c, three sets of nonlinear frequency modulation waveforms having the same range shift amount ΔR are selected.
Therefore, if the frequency modulation unit 2 is composed of two frequency modulators, two sets of nonlinear frequency modulation waveforms having the same range shift amount ΔR are selected, and the frequency modulation unit 2 includes four or more frequency modulators. 4 or more sets of four or more sets of non-linear frequency modulation waveforms with the same range shift amount ΔR are selected.

If the number of nonlinear frequency modulation waveforms with the same range shift amount ΔR is less than the number of frequency modulators constituting the frequency modulator 2, the number of nonlinear frequencies corresponding to the number of frequency modulators Until the modulation waveform (nonlinear frequency modulation waveform in which the range shift amount ΔR becomes equal) is obtained, the parameter fluctuation width Δ (i) is finely divided twice to obtain a plurality of different chirp rates at the center and end of the pulse. A non-linear frequency modulation waveform is generated and the same processing is repeated.
FIG. 5 is an explanatory diagram showing an example of a non-linear frequency modulation waveform having the same range shift amount ΔR selected by the modulation waveform selection unit 1.

When the modulation waveform selection unit 1 selects a plurality of nonlinear frequency modulation waveforms having the same range shift amount ΔR, the frequency modulation unit 2 modulates the transmission signal using each nonlinear frequency modulation waveform, thereby modulating the transmission signal. A modulated signal that is a subsequent transmission signal is output to the transmission processing unit 3 and the modulated signal is output to the correlation processing unit 7 as a reference signal.
That is, the frequency modulator 2a of the frequency modulation unit 2 frequency-modulates the transmission signal using the nonlinear frequency modulation waveform selected by the modulation waveform selection unit 1, and sends the modulated signal, which is the modulated transmission signal, to the transmitter 3a. The modulated signal is output to the correlation processors 7a, 7d, and 7g as a reference signal.
Further, the frequency modulator 2b frequency-modulates the transmission signal using the nonlinear frequency modulation waveform selected by the modulation waveform selection unit 1, and outputs the modulated signal, which is the modulated transmission signal, to the transmitter 3b. The modulated signal is output as a reference signal to the correlation processors 7b, 7e, and 7h.
The frequency modulator 2c frequency-modulates the transmission signal using the non-linear frequency modulation waveform selected by the modulation waveform selection unit 1, and outputs the modulated signal, which is the modulated transmission signal, to the transmitter 3c. The modulated signal is output as a reference signal to the correlation processors 7c, 7f, 7i.

When the transmission processing unit 3 receives a plurality of modulation signals from the frequency modulation unit 2, the transmission processing unit 3 supplies the plurality of modulation signals to the transmission array antenna 4 to radiate the modulation signal from the transmission array antenna 4 to the space as a transmission RF signal. .
That is, the transmitter 3a of the transmission processing unit 3 supplies the modulation signal output from the frequency modulator 2a to the transmission antenna 4a, and radiates the modulation signal from the transmission antenna 4a to the space as a transmission RF signal.
In addition, the transmitter 3b supplies the modulation signal output from the frequency modulator 2b to the transmission antenna 4b, thereby radiating the modulation signal from the transmission antenna 4b to the space as a transmission RF signal.
Further, the transmitter 3c supplies the modulation signal output from the frequency modulator 2c to the transmission antenna 4c, and thereby radiates the modulation signal from the transmission antenna 4c to the space as a transmission RF signal.

The receiving array antenna 5 receives, as reflected RF signals, a plurality of RF signals which are radiated from the transmitting array antenna 4 to the space and then reflected back to the target existing in the space.
The reflected RF signals received by the receiving antennas 5a, 5b, and 5c of the receiving array antenna 5 are reflected by the three types of RF signals radiated from the transmitting antennas 4a, 4b, and 4c, and the three types of RF signals. Therefore, the reflected RF signals received by the receiving antennas 5a, 5b, and 5c are all the same signal.

The reception processing unit 6 outputs a plurality of reflected RF signals received by the reception array antenna 5 to the correlation processing unit 7 as reception signals.
That is, the receiver 6a of the reception processing unit 6 outputs the reflected RF signal received by the reception antenna 5a as a reception signal to the correlation processors 7a to 7c.
The receiver 6b outputs the reflected RF signal received by the receiving antenna 5b to the correlation processors 7d to 7f as a received signal.
The receiver 6c outputs the reflected RF signal received by the receiving antenna 5c as a received signal to the correlation processors 7g to 7i.

The correlation processing unit 7 performs correlation processing between the plurality of reception signals output from the reception processing unit 6 and the plurality of reference signals output from the frequency modulation unit 2, and obtains the peak value of each correlation processing result. Output to the beam combiner 8.
That is, the correlation processor 7a of the correlation processing unit 7 performs correlation processing between the received signal output from the receiver 6a and the reference signal output from the frequency modulator 2a, and the peak value of the correlation processing result. Is output to the beam combiner 8.
The correlation processor 7b performs correlation processing between the reception signal output from the receiver 6a and the reference signal output from the frequency modulator 2b, and outputs the peak value of the correlation processing result to the beam combiner 8. To do.
The correlation processor 7c performs correlation processing between the reception signal output from the receiver 6a and the reference signal output from the frequency modulator 2c, and outputs the peak value of the correlation processing result to the beam combiner 8. To do.

The correlation processor 7d of the correlation processing unit 7 performs correlation processing between the reception signal output from the receiver 6b and the reference signal output from the frequency modulator 2a, and the peak value of the correlation processing result is converted into a beam. Output to the synthesizer 8.
The correlation processor 7e performs correlation processing between the reception signal output from the receiver 6b and the reference signal output from the frequency modulator 2b, and outputs the peak value of the correlation processing result to the beam combiner 8. To do.
The correlation processor 7f performs correlation processing between the reception signal output from the receiver 6b and the reference signal output from the frequency modulator 2c, and outputs the peak value of the correlation processing result to the beam combiner 8. To do.

The correlation processor 7g of the correlation processing unit 7 performs correlation processing between the reception signal output from the receiver 6c and the reference signal output from the frequency modulator 2a, and the peak value of the correlation processing result is converted into a beam. Output to the synthesizer 8.
The correlation processor 7h performs correlation processing between the reception signal output from the receiver 6c and the reference signal output from the frequency modulator 2b, and outputs the peak value of the correlation processing result to the beam combiner 8. To do.
The correlation processor 7i performs correlation processing between the reception signal output from the receiver 6c and the reference signal output from the frequency modulator 2c, and outputs the peak value of the correlation processing result to the beam combiner 8. To do.
Since the correlation process itself is a known technique, a detailed description is omitted. However, the range shift amount ΔR that takes the peak value of the correlation process result in the correlation processors 7a to 7i is selected by selecting the same frequency modulation waveform. Yes.

  When the beam combiner 8 receives the peak values of the correlation processing results from the correlation processors 7a to 7i, the beam combiner 8 adds the peak values to obtain the beam combining result.

  As apparent from the above, according to the first embodiment, the nonlinear frequency at which the range shift amount ΔR by the Doppler frequency is equal among the plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and the end of the pulse. Modulation waveform selection unit 1 that selects a combination of modulation waveforms, and frequency modulation that generates a plurality of modulation signals by frequency-modulating a transmission signal using each nonlinear frequency modulation waveform selected by modulation waveform selection unit 1 Unit 2, a transmission processing unit 3 that radiates a plurality of modulated signals generated by the frequency modulation unit 2 to the space from the transmission array antenna 4, and is radiated from the transmission array antenna 4 to the space and then exists in the space A reception processing unit 6 that receives a plurality of modulated signals reflected back to the target and returned to the reception array antenna 5, and the correlation processing unit 7 performs reception processing. 6 performs correlation processing between a plurality of received signals received by 6 and a reference signal, which is a plurality of modulated signals generated by the frequency modulator 2, and the beam combiner 8 adds the peak values of the respective correlation processing results Thus, there is an effect that beam combining can be performed by properly separating a plurality of received signals received by the reception processing unit 6 by correlation processing.

  In the first embodiment, an example in which the number of antennas of the transmission array antenna 4 and the reception array antenna 5 is 3 is shown. However, when the number of antennas is 2 or when the number of antennas is 4 or more, Beam synthesis can be performed by the same processing.

Embodiment 2. FIG.
In the first embodiment, the modulation waveform selection unit 1 has the same overall pulse width T ₀ , overall bandwidth B ₀ , central pulse width T, and end pulse width dt, and the central bandwidth. FIG. 6 shows a selection of a combination of nonlinear frequency modulation waveforms in which the range shift amount ΔR due to the Doppler frequency is equal from among a plurality of nonlinear frequency modulation waveforms having different B and end bandwidths df. As shown, the overall pulse width T ₀ , the overall bandwidth B ₀ , the central bandwidth B and the end bandwidth df are the same, but the central pulse width T and the end pulse width dt are different. Even if a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency is selected from a plurality of nonlinear frequency modulation waveforms, the same effect can be obtained.

In addition, as shown in FIG. 7, the modulation waveform selection unit 1 has the same total pulse width T ₀ , central pulse width T, central bandwidth B, and end pulse width dt. Even if a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency is selected from a plurality of nonlinear frequency modulation waveforms having different widths B ₀ and end bandwidths df, There is an effect.

Further, as shown in FIG. 8, the modulation waveform selection unit 1 has the same overall pulse width T ₀ , central pulse width T, end pulse width dt, and end bandwidth df. Even if a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency is selected from a plurality of nonlinear frequency modulation waveforms having different widths B ₀ and central bandwidth B, There is an effect.

Further, as shown in FIG. 9, the modulation waveform selection unit 1 has the same overall pulse width T ₀ , central bandwidth B, and end slope df / dt, and the overall bandwidth B ₀ and central portion. Even if a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency is selected from a plurality of nonlinear frequency modulation waveforms having different pulse widths T, the same effect can be obtained. .

Further, as shown in FIG. 10, the modulation waveform selector 1 has the same overall bandwidth B ₀ , central pulse width T, central bandwidth B, and end bandwidth df, and the entire pulse. Even if a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency is selected from a plurality of nonlinear frequency modulation waveforms having different widths T ₀ and pulse widths dt at the ends, the same applies. There is an effect.

Further, as shown in FIG. 11, the modulation waveform selection unit 1 has the same overall bandwidth B ₀ , central pulse width T, and end slope df / dt, and the entire pulse width T ₀ and central portion. Even if a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR by the Doppler frequency is selected from a plurality of nonlinear frequency modulation waveforms having different bandwidths B, the same effect can be obtained. .

Further, as shown in FIG. 12, the modulation waveform selection unit 1 has the same overall bandwidth B ₀ , central bandwidth B, and end slope df / dt, and the overall pulse width T ₀ and central portion. Even if a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency is selected from a plurality of nonlinear frequency modulation waveforms having different pulse widths T, the same effect can be obtained. .

  Further, as shown in FIG. 13, the modulation waveform selection unit 1 has the same center B slope T / end, end slope df / dt, end pulse width dt, and end bandwidth df. A combination of nonlinear frequency modulation waveforms in which the range shift amount ΔR due to the Doppler frequency is equal may be selected from a plurality of nonlinear frequency modulation waveforms having different pulse widths T and central bandwidths B. Similar effects can be achieved.

  Further, as shown in FIG. 14, the modulation waveform selection unit 1 has the same pulse width T at the central portion, the bandwidth B at the central portion, and the slope df / dt at the end portion, and the pulse width dt at the end portion and the end portion. The same effect can be obtained by selecting a combination of non-linear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency from among a plurality of non-linear frequency modulation waveforms having different bandwidths df. .

Further, as shown in FIG. 15, the modulation waveform selection unit 1 has the same overall pulse width T ₀ and overall bandwidth B ₀ , the central pulse width T, the central bandwidth B, and the end bandwidth B ₀ . A combination of non-linear frequency modulation waveforms in which the range shift amount ΔR due to the Doppler frequency is equal is selected from a plurality of non-linear frequency modulation waveforms having at least one different pulse width dt and end bandwidth df. However, the same effect can be obtained.

Embodiment 3 FIG.
FIG. 16 is a block diagram showing a radar apparatus according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in FIG.
The modulation waveform selection unit 10 performs a process of selecting a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency from a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and the end of the pulse. To do.
That is, the modulation waveform selection unit 10 is a nonlinear frequency modulation waveform represented by the inverse of a function obtained by adding a sin function and a linear chirp function having a constant frequency change rate, and the weight of the sin function for the linear chirp function. A process of selecting a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency is selected from a plurality of nonlinear frequency modulation waveforms having different values. The modulation waveform selection unit 10 constitutes a modulation waveform selection unit.
In the example of FIG. 16, since the frequency modulation unit 2 is composed of three frequency modulators 2a, 2b, and 2c, three sets of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency are selected.

Next, the operation will be described.
Since the configuration other than the modulation waveform selection unit 10 is the same as that of the first embodiment, only the processing contents of the modulation waveform selection unit 10 will be described.
FIG. 17 is an explanatory diagram showing a non-linear frequency modulation waveform represented by the reciprocal of a function obtained by adding a sin function and a linear chirp function.
In the example of FIG. 17, the horizontal axis represents the pulse width normalized at −0.5 to 0.5, and the bandwidth normalized at −0.5 to 0.5 with the transmission frequency as the center. It is shown on the vertical axis.

式（４）において、ｋは線形チャープ関数に対するｓｉｎ関数の重みパラメータであり、ｆは送信周波数である。
この実施の形態３では、変調波形選択部１０が、重みパラメータｋを変更して、非線形性の強弱を調節することで、パルスの中心部と端部におけるチャープ率が異なる複数の非線形周波数変調波形を生成する。 The nonlinear frequency modulation waveform in FIG. 17 is represented by a function t (f) shown in the following equation (4).

In Equation (4), k is a weight parameter of a sin function for a linear chirp function, and f is a transmission frequency.
In the third embodiment, the modulation waveform selection unit 10 changes the weight parameter k and adjusts the strength of the nonlinearity, whereby a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and the end of the pulse. Is generated.

When the modulation waveform selection unit 10 generates a plurality of nonlinear frequency modulation waveforms, similarly to the modulation waveform selection unit 1 of FIG. 1, the nonlinearity in which the range shift amount ΔR due to the Doppler frequency becomes equal among the plurality of nonlinear frequency modulation waveforms. Select a combination of frequency modulation waveforms.
FIG. 18 is an explanatory diagram showing an example of a nonlinear frequency modulation waveform having the same range shift amount ΔR selected by the modulation waveform selection unit 10.

  As apparent from the above, according to the third embodiment, the modulation waveform selection unit 10 is a nonlinear frequency modulation waveform represented by the inverse of a function obtained by adding a sin function and a linear chirp function. Since a plurality of nonlinear frequency modulation waveforms having different sin function weights with respect to the linear chirp function are generated, as in the first and second embodiments, the nonlinear frequency at which the range shift amount ΔR by the Doppler frequency becomes equal. There is an effect that a combination of modulation waveforms can be selected.

  Here, the modulation waveform selection unit 10 selects a combination of nonlinear frequency modulation waveforms in which the range shift amount ΔR due to the Doppler frequency is equal from among a plurality of nonlinear frequency modulation waveforms having different sin function weights with respect to the linear chirp function. As shown, a plurality of nonlinear frequency modulation waveforms having different sin function weights with respect to the linear chirp function, and a plurality of modulation waveforms generated by the modulation waveform selection unit 1 of FIG. You may make it select the combination of the nonlinear frequency modulation waveform from which the range shift amount (DELTA) R by a Doppler frequency becomes equal from a nonlinear frequency modulation waveform.

Embodiment 4 FIG.
FIG. 19 is a block diagram showing a radar apparatus according to Embodiment 4 of the present invention. In the figure, the same reference numerals as those in FIG.
The modulation waveform selection unit 20 performs a process of selecting a combination of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency from a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and the end of the pulse. To do.
That is, the modulation waveform selection unit 20 is a nonlinear frequency modulation waveform in which the tan function is expressed by a function normalized by the pulse width and the bandwidth, and a plurality of nonlinear frequency modulations having different tan function phase parameters β. A process of selecting a combination of nonlinear frequency modulation waveforms in which the range shift amount ΔR due to the Doppler frequency is equal is performed from the waveforms. The modulation waveform selection unit 20 constitutes modulation waveform selection means.
In the example of FIG. 19, since the frequency modulation unit 2 is composed of three frequency modulators 2a, 2b, and 2c, three sets of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency are selected.

Next, the operation will be described.
Since the configuration other than the modulation waveform selection unit 20 is the same as that of the first embodiment, only the processing contents of the modulation waveform selection unit 20 will be described.
FIG. 20 is an explanatory diagram showing a nonlinear frequency modulation waveform in which the tan function is represented by a function that is normalized by the pulse width and the bandwidth.
In the example of FIG. 20, the horizontal axis represents the pulse width normalized at −0.5 to 0.5, and the bandwidth normalized at −0.5 to 0.5 with the transmission frequency as the center. It is shown on the vertical axis.

式（５）において、βはｔａｎ関数の位相パラメータである。
この実施の形態４では、変調波形選択部２０が、位相パラメータβを変更して、非線形性の強弱を調節することで、パルスの中心部と端部におけるチャープ率が異なる複数の非線形周波数変調波形を生成する。 The nonlinear frequency modulation waveform in FIG. 20 is represented by a function f (t) shown in the following equation (5).

In Expression (5), β is a phase parameter of the tan function.
In the fourth embodiment, the modulation waveform selection unit 20 changes the phase parameter β and adjusts the strength of the nonlinearity, whereby a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and the end of the pulse. Is generated.

When the modulation waveform selection unit 20 generates a plurality of nonlinear frequency modulation waveforms, as in the modulation waveform selection unit 1 of FIG. 1, the nonlinearity in which the range shift amount ΔR due to the Doppler frequency becomes equal among the plurality of nonlinear frequency modulation waveforms. Select a combination of frequency modulation waveforms.
FIG. 21 is an explanatory diagram illustrating an example of a nonlinear frequency modulation waveform having the same range shift amount ΔR selected by the modulation waveform selection unit 20.

  As apparent from the above, according to the fourth embodiment, the modulation waveform selection unit 20 is a nonlinear frequency modulation waveform represented by a function in which the tan function is normalized by the pulse width and the bandwidth, Since a plurality of nonlinear frequency modulation waveforms having different tan function phase parameters β are generated, as in the first and second embodiments, the nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency are used. There is an effect that a combination of the above can be selected.

  Here, the modulation waveform selection unit 20 selects a combination of nonlinear frequency modulation waveforms in which the range shift amount ΔR by the Doppler frequency is equal from a plurality of nonlinear frequency modulation waveforms having different tan function phase parameters β. Are shown, but a plurality of nonlinear frequency modulation waveforms with different phase parameters β of the tan function and a plurality of nonlinear frequency modulation waveforms generated by the modulation waveform selection unit 1 of FIG. A combination of nonlinear frequency modulation waveforms with the same range shift amount ΔR depending on the Doppler frequency may be selected.

Embodiment 5 FIG.
22 is a block diagram showing a radar apparatus according to Embodiment 5 of the present invention. In the figure, the same reference numerals as those in FIG.
The modulation waveform selection unit 30 performs a process of selecting a combination of nonlinear frequency modulation waveforms in which the range shift amount ΔR due to the Doppler frequency is equal from a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and end of the pulse. To do.
That is, the modulation waveform selection unit 30 is a nonlinear frequency modulation waveform whose end is expressed by a function obtained by adding a hyperbolic function and a linear chirp function having a constant frequency change rate, and whose center is expressed by the linear chirp function. A process of selecting a combination of non-linear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency is selected from a plurality of non-linear frequency modulation waveforms having different pulse widths and bandwidths occupied by the hyperbolic function. . The modulation waveform selection unit 30 constitutes a modulation waveform selection unit.
In the example of FIG. 22, since the frequency modulation unit 2 is composed of three frequency modulators 2a, 2b, and 2c, three sets of nonlinear frequency modulation waveforms having the same range shift amount ΔR due to the Doppler frequency are selected.

Next, the operation will be described.
Since the configuration other than the modulation waveform selection unit 30 is the same as that of the first embodiment, only the processing content of the modulation waveform selection unit 30 will be described.
FIG. 23 is an explanatory diagram showing a nonlinear frequency modulation waveform whose end portion is expressed by a function obtained by adding a hyperbolic function and a linear chirp function, and whose central portion is expressed by the linear chirp function.
In the example of FIG. 23, the horizontal axis represents the pulse width normalized at −0.5 to 0.5, and the bandwidth normalized at −0.5 to 0.5 with the transmission frequency as the center. It is shown on the vertical axis.

The nonlinear frequency modulation waveform in FIG. 23 is represented by a function f (t) shown in the following equation (6).

FIG. 24 is an explanatory diagram showing the hyperbolic function used at the right end of the pulse, and FIG. 25 is an explanatory diagram showing the hyperbolic function used at the left end of the pulse.
In the hyperbolic function shown in FIG. 24, a range in which the domain width is dt and the range width is df is cut out from the hyperbola of the proportionality constant χ, and the range of the cut-out range is [0, df]. Is translated so as to be [T / 2-dt, T / 2].
In the hyperbolic function shown in FIG. 25, a range in which the domain width is dt and the range is df is extracted from the hyperbola of the proportionality constant χ, and the range of the extracted range is [−df, 0], the definition. The region is translated so that the region becomes [−T / 2, −T / 2 + dt].

  In the fifth embodiment, the modulation waveform selection unit 30 changes the modulation parameters df and dt and adjusts the strength of the nonlinearity, whereby a plurality of nonlinear frequencies having different chirp rates at the center and the end of the pulse. Generate a modulated waveform. The modulation parameters df and dt are changed by the same method as that of the modulation waveform selection unit in FIG.

When the modulation waveform selection unit 30 generates a plurality of nonlinear frequency modulation waveforms, like the modulation waveform selection unit 1 in FIG. 1, the nonlinearity in which the range shift amount ΔR due to the Doppler frequency becomes equal among the plurality of nonlinear frequency modulation waveforms. Select a combination of frequency modulation waveforms.
FIG. 26 is an explanatory diagram showing an example of a non-linear frequency modulation waveform having the same range shift amount ΔR selected by the modulation waveform selection unit 30.

  As is apparent from the above, according to the fifth embodiment, the modulation waveform selection unit 30 is represented by a function obtained by adding a hyperbola function and a linear chirp function at the end, and the center portion is represented by the linear chirp function. As shown in the first and second embodiments, since a plurality of nonlinear frequency modulation waveforms having different pulse widths and bandwidths occupied by their hyperbolic functions are generated. There is an effect that it is possible to select a combination of nonlinear frequency modulation waveforms in which the range shift amount ΔR by the Doppler frequency becomes equal.

  Here, the modulation waveform selection unit 30 selects a combination of nonlinear frequency modulation waveforms in which the range shift amount ΔR due to the Doppler frequency is equal from among a plurality of nonlinear frequency modulation waveforms having different pulse widths and bandwidths occupied by the hyperbolic function. As shown in FIG. 27, a plurality of nonlinear frequency modulation waveforms having different pulse widths and bandwidths occupied by the hyperbolic function, and the modulation waveforms of FIG. You may make it select the combination of the nonlinear frequency modulation waveform from which the range shift amount (DELTA) R by a Doppler frequency becomes equal from the some nonlinear frequency modulation waveform produced | generated by the selection part 1. FIG.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  1, 10, 20, 30 Modulation waveform selection unit (modulation waveform selection unit), 2 Frequency modulation unit (frequency modulation unit), 2a, 2b, 2c Frequency modulator, 3 Transmission processing unit (signal transmission unit), 3a, 3b , 3c transmitter, 4 transmitting array antenna (signal transmitting means), 4a, 4b, 4c transmitting antenna, 5 receiving array antenna (signal receiving means), 5a, 5b, 5c receiving antenna, 6 reception processing section (signal receiving means) , 6a, 6b, 6c receiver, 7 correlation processor, 7a-7i correlation processor (beam combining means), 8 beam combiner (beam combining means).

Claims (18)

  Modulation waveform selection means for selecting a combination of nonlinear frequency modulation waveforms with the same range shift amount due to the Doppler frequency from among a plurality of nonlinear frequency modulation waveforms having different chirp rates at the center and end of the pulse, and the modulation waveform selection Frequency modulation means for generating a plurality of modulation signals by frequency-modulating the transmission signal using each nonlinear frequency modulation waveform selected by the means, and a plurality of modulation signals generated by the frequency modulation means in the space A signal transmitting means for radiating; a signal receiving means for receiving, as a received signal, a plurality of modulated signals that have been radiated from the signal transmitting means to the space and then returned to the target existing in the space; and the signal A plurality of received signals received by the receiving means and a reference signal which is a plurality of modulated signals generated by the frequency modulating means Seki process performed, a radar device that includes a beam combining means for adding the peak values of each of the correlation processing result.   The modulation waveform selection means includes a plurality of nonlinear frequencies having the same overall pulse width, overall bandwidth, central pulse width and end pulse width, but different center bandwidth and end bandwidth. The radar apparatus according to claim 1, wherein a combination of non-linear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected from the modulation waveforms.   The modulation waveform selection means has a plurality of nonlinear frequencies in which the entire pulse width, the entire bandwidth, the center bandwidth and the end bandwidth are the same, but the center pulse width and the end pulse width are different. The radar apparatus according to claim 1, wherein a combination of non-linear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected from the modulation waveforms.   The modulation waveform selection means has a plurality of nonlinear frequencies having the same overall pulse width, central pulse width, central bandwidth and end pulse width, but different overall bandwidth and end bandwidth. The radar apparatus according to claim 1, wherein a combination of non-linear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected from the modulation waveforms.   The modulation waveform selection means has a plurality of non-linear frequencies having the same overall pulse width, central pulse width, end pulse width, and end bandwidth, but different overall bandwidth and center bandwidth. The radar apparatus according to claim 1, wherein a combination of non-linear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected from the modulation waveforms.   The modulation waveform selecting means is configured to perform Doppler from a plurality of nonlinear frequency modulation waveforms having the same overall pulse width, central bandwidth and end slope, but different overall bandwidth and central pulse width. The radar apparatus according to claim 1, wherein a combination of nonlinear frequency modulation waveforms having the same range shift amount according to frequency is selected.   The modulation waveform selection means has a plurality of nonlinear frequencies having the same overall bandwidth, central pulse width, central bandwidth and end bandwidth, but different overall pulse width and end pulse width. The radar apparatus according to claim 1, wherein a combination of non-linear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected from the modulation waveforms.   The modulation waveform selection means is configured to perform Doppler from a plurality of nonlinear frequency modulation waveforms having the same overall bandwidth, center pulse width and end slope, but different overall pulse width and center bandwidth. The radar apparatus according to claim 1, wherein a combination of nonlinear frequency modulation waveforms having the same range shift amount according to frequency is selected.   The modulation waveform selection means has a Doppler from a plurality of nonlinear frequency modulation waveforms having the same overall bandwidth, central bandwidth and end slope, but different overall pulse width and central pulse width. The radar apparatus according to claim 1, wherein a combination of nonlinear frequency modulation waveforms having the same range shift amount according to frequency is selected.   The modulation waveform selection means has a plurality of nonlinear frequencies having the same center slope, end slope, end pulse width and end bandwidth, but different center pulse width and center bandwidth. The radar apparatus according to claim 1, wherein a combination of non-linear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected from the modulation waveforms.   The modulation waveform selecting means has a pulse width at the central portion, a bandwidth at the central portion, and an inclination at the end portion, and a plurality of nonlinear frequency modulation waveforms having the same pulse width at the end portion and different bandwidths at the end portions. 2. The radar apparatus according to claim 1, wherein a combination of nonlinear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected.   The modulation waveform selection means has the same overall pulse width and overall bandwidth, and at least one of the center pulse width, the center bandwidth, the end pulse width, and the end bandwidth is different. 2. The radar apparatus according to claim 1, wherein a combination of nonlinear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected from a plurality of nonlinear frequency modulation waveforms.   The modulation waveform selection means is a non-linear frequency modulation waveform represented by the inverse of a function obtained by adding a sin function and a linear chirp function having a constant frequency change rate, and the weight of the sin function with respect to the linear chirp function is 2. The radar apparatus according to claim 1, wherein a combination of nonlinear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected from a plurality of different nonlinear frequency modulation waveforms.   The modulation waveform selection means is a non-linear frequency modulation waveform represented by the inverse of a function obtained by adding a sin function and a linear chirp function having a constant frequency change rate, and the weight of the sin function with respect to the linear chirp function is The range shift amount by the Doppler frequency becomes equal from among the plurality of different nonlinear frequency modulation waveforms and the plurality of nonlinear frequency modulation waveforms described in any one of claims 2 to 13. 2. The radar apparatus according to claim 1, wherein a combination of nonlinear frequency modulation waveforms is selected.   The modulation waveform selection means is a non-linear frequency modulation waveform whose tan function is expressed by a function normalized by a pulse width and a bandwidth, and a plurality of non-linear frequency modulation waveforms having different phase parameters of the tan function. 2. The radar apparatus according to claim 1, wherein a combination of non-linear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected.   The modulation waveform selecting means is a non-linear frequency modulation waveform represented by a function in which the tan function is normalized by a pulse width and a bandwidth, and a plurality of non-linear frequency modulation waveforms having different phase parameters of the tan function Selecting a combination of nonlinear frequency modulation waveforms in which the amount of range shift due to the Doppler frequency is equal from among the plurality of nonlinear frequency modulation waveforms described in any one of claims 2 to 13 The radar apparatus according to claim 1.   The modulation waveform selection means is a nonlinear frequency modulation waveform whose end is expressed by a function obtained by adding a hyperbolic function and a linear chirp function having a constant frequency change rate, and whose center is expressed by the linear chirp function. A combination of non-linear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected from a plurality of non-linear frequency modulation waveforms having different pulse widths and bandwidths occupied by the hyperbolic function. The radar apparatus according to 1.   The modulation waveform selection means is a nonlinear frequency modulation waveform whose end is expressed by a function obtained by adding a hyperbolic function and a linear chirp function having a constant frequency change rate, and whose center is expressed by the linear chirp function. A plurality of nonlinear frequency modulation waveforms having different pulse widths and bandwidths occupied by the hyperbolic function, and a plurality of nonlinear frequency modulation waveforms according to any one of claims 2 to 13 2. The radar apparatus according to claim 1, wherein a combination of non-linear frequency modulation waveforms having the same range shift amount due to the Doppler frequency is selected.

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