JP2013124888A - Radar system and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a target by using signals over a wider range through simple processing.SOLUTION: A radar system comprises a transmitter, a receiver, a corrector, a band interpolation processor and a signal processor. The transmitter transmits a first chirp pulse of a first frequency band and a second chirp pulse of a second frequency band different from the first frequency band to a target. The receiver receives a first reception signal and a second reception signal from the target. The corrector uses a correction value table to correct phases of the first and second reception signals and determines first and second correction spectrums. The band interpolation processor interpolates a signal of a band between the first frequency band and the second frequency band to a signal obtained by coupling the first and second correction spectrums and generates an interpolation signal representing a reflection wave from the target regarding chirp signals from the first frequency band to the second frequency band. The signal processor uses the interpolation signal to determine a distance to the target.

Description

  The present invention relates to a radar apparatus and a method for detecting a target using the radar apparatus.

  A radar device may be used to detect a target and calculate a distance to the detected target. The radar apparatus transmits a radar wave toward the target and receives a reflected wave from the target. Furthermore, the radar apparatus obtains the distance from the target by analyzing the received radar signal. The distance resolution at this time varies depending on the width of the frequency band of the received signal, and the resolution of the radar apparatus can be improved by increasing the frequency bandwidth of the received signal that can be acquired by the radar apparatus.

  In order to widen the frequency bandwidth of the received signal, it is conceivable to widen the bandwidth of the radar wave transmitted from the radar apparatus. As one of the methods for widening the bandwidth, a pulse compression radar device has been devised that emits chirp pulses with different frequency bands at a constant period and receives a reflected wave reflected by a target. The pulse compression radar apparatus combines the received reflected waves and converts them into a time-compressed impulse signal.

  Further, each of the first and second radar signals is separated into primary and secondary response signals by a threshold on the time axis, and the phases of the first and second radar signals are respectively determined for the primary and secondary response signals. A method of performing band interpolation by linear prediction after matching (coherent) is also devised. In this method, the band-interpolated primary and secondary response signals are combined, and the number and intensity of combined radar signal responses and the distance between the radar signal responses are checked against a database.

JP 2002-82162 A JP 2005-180970 A

  In the method of combining received waves using chirp pulses with different frequency bands, in order to increase the bandwidth to be used, it is required to obtain permission for use in the radar device over the entire area of the bandwidth to be used. It is done. However, since the frequency band is finite, the band that can be used by the radar apparatus is limited. Also, the radar apparatus is equipped with hardware that can perform wideband processing, so that it is difficult to design the hardware, and it is difficult to widen the frequency band with the method of combining received waves.

  In the method of performing band interpolation by linear prediction after matching the phases of the first and second radar signals, interpolation is performed by linear prediction even if the band of the actually transmitted / received signal is not wide. However, this method has a problem that it takes too much time to obtain a phase fluctuation amount for matching the phases of the radar signals. For example, in the process for matching the phase of the first radar signal to the phase of the second radar signal, first, a singular point for each signal is obtained from the first and second radar signals. Here, the singular point is a frequency component of the target scattering center. Next, a phase fluctuation amount for making the phase of the singular point of the first radar signal coincide with the phase of the singular point of the radar signal obtained by the second radar apparatus is obtained. Finally, the phase of the entire first radar signal is changed according to the obtained fluctuation amount. As described above, in the method of improving the resolution using band interpolation, a large amount of calculation is performed before band interpolation, which increases the load on the radar apparatus.

  An object of this invention is to provide the radar apparatus which can detect a target using the received signal over a wide range by simple processing.

  The radar apparatus includes a transmission unit, a reception unit, a correction unit, a band interpolation processing unit, and a signal processing unit. The transmission unit transmits a first chirp pulse over a first frequency band and a second chirp pulse over a second frequency band different from the first frequency band toward a target to be observed. The receiving unit receives a first received signal that is a reflected wave of the first chirp pulse from the target and a second received signal that is a reflected wave of the second chirp pulse. The correction unit obtains a first correction spectrum by correcting the phase of the first reception signal with a correction value recorded in a correction value table, and corrects the phase of the second reception signal by the correction value. The second corrected spectrum is obtained by correcting with the value. The band interpolation processing unit interpolates a signal in a band between the first frequency band and the second frequency band to a signal obtained by combining the first and second correction spectra. By this processing, the band interpolation processing unit generates an interpolation signal representing a reflected wave obtained when the target is irradiated with a chirp signal from the first frequency band to the second frequency band. The signal processing unit obtains the distance to the target using the interpolation signal.

  The target can be detected using a wide range of received signals with simple processing.

It is a figure which shows the example of a structure of the radar apparatus concerning 1st Embodiment. It is a figure which shows the example of the frequency band used for the production | generation of a pulse. It is a figure which shows the example of a structure of a band interpolation processor. It is a figure which shows the example of a correction value table. It is a figure which shows the example of the hardware constitutions of a radar apparatus. It is a figure which shows the example of a transmission wave and a reception wave. It is a figure explaining the example of a process of a received wave. It is an example of the table which a buffer hold | maintains. It is a table which shows the example of the process in an electrical length correction | amendment part. It is a flowchart explaining the example of operation | movement of a band interpolation processor. It is a figure which shows the example of a structure of the radar apparatus concerning 2nd Embodiment. It is a figure which shows the example of a structure of the radar apparatus which concerns on 3rd Embodiment. It is a figure which shows the example of the relationship between a frequency band and a gain. It is a figure explaining the example of the process performed in 3rd Embodiment. It is a figure which shows the example of a structure of a radar apparatus. It is a figure which shows the example of a structure of a radar apparatus. It is a figure which shows the example of the table used for the determination of a frequency band and a pulse width. It is a figure which shows the example of the transmission wave and reception wave in 5th Embodiment. It is a figure explaining the example of the process performed with respect to a received wave in 5th Embodiment. It is a figure which shows the example of the transmission wave and reception wave which were output from the radar apparatus. It is a figure which shows the example of a structure of a radar apparatus. It is a figure which shows the example of a structure of a radar apparatus. It is a figure which shows the example of a structure of a radar apparatus.

  The processing for obtaining the phase fluctuation amount for matching the phases of the two radar signals prior to the band interpolation requires a large amount of calculation, so that the burden on the radar apparatus is large. Here, the phase fluctuation amount includes a first transmitter that irradiates a first radar wave transmitted to obtain a first radar signal, and a second transmitter that is transmitted to obtain a second radar signal. It fluctuates according to the distance between the second transmitters that irradiate the radar wave.

  Therefore, in the radar apparatus according to the embodiment, the correction value for adjusting the phase is obtained by setting the difference between the positions where two transmission pulses having different wavelengths are transmitted to a fixed value that is uniquely determined according to the frequency. Stored in advance as a function of frequency. The radar apparatus according to the embodiment can easily obtain data used for band interpolation by matching the phases of two radar signals using stored correction values. For this reason, the load which the process for adjusting the phase of a radar signal places on a radar apparatus is reduced. Furthermore, since the radar apparatus according to the embodiment can perform band interpolation, a signal for a wavelength not irradiated from the radar apparatus can also be obtained by calculation, with the same accuracy as when using a frequency over a wide band. Distance can be measured. The positions where the two transmission pulses are transmitted may be the same. In this case, transmission pulses having different frequency bands are output at different times from one transmission antenna.

<Device configuration>
FIG. 1 shows an example of the configuration of a radar apparatus according to the first embodiment. The radar apparatus 10 includes a frequency synthesizer 11, a frequency filter 12, a pulse modulator 13, a high output amplifier 14, a controller 20, a transmission / reception switch 30, and a transmission / reception antenna 31. The radar apparatus 10 further includes a frequency filter 41 (41a, 41b), a low noise amplifier 42, a reception mixer 43, an intermediate frequency amplifier 45, a duplexer 46, an A / D converter 47 (47a to 47c), and a signal processor. 48, a display 49, and a band interpolation processor 50. In the following description, it is assumed that transmission pulses of three types of frequency bands are used and the received signal is processed by different A / D converters 47 for each type of transmission pulse. The number of types of frequency bands is arbitrary. The number of A / D converters 47 provided in the radar apparatus 10 is also arbitrarily changed. For example, the radar apparatus 10 may include one A / D converter 47. When there is one A / D converter 47, the received signal is input to the A / D converter 47 at a predetermined period. A digital I / Q signal is recorded for each received signal.

  The radar apparatus 10 can transmit any type of transmission pulse signal set in advance from the transmission / reception antenna 31. Each type of transmission pulse is a pulse having a wavelength in a different frequency band from the other types of transmission pulses. In the following description, it is assumed that three types of pulses are used. Moreover, the frequency used by each pulse shall be either f1-f2, f3-f4, f5-f6. In the following description, it is assumed that f1 <f2 <f3 <f4 <f5 <f6.

The controller 20 determines a frequency band to be used for generating a pulse according to the timing for generating the pulse. For example, the controller 20 can determine the frequency band according to the table shown in FIG. In this case, the controller 20 designates a band of f1 to f2 for the first generated pulse, f3 to f4 for the second pulse, and a band of f5 to f6 for the third pulse. specify. After that, the controller 20 designates the bands f1 to f2, f3 to f4, and f5 to f6 in order. That is, the controller 20
(3n + 1) th generated pulse: f1 to f2
(3n + 2) th generated pulse: f3 to f4
3nth generated pulse: f5 to f6
The frequency band is designated so that Here, n is an arbitrary integer of 0 or more. The controller 20 notifies the frequency synthesizer 11 and the duplexer 46 of the determined frequency band.

  The frequency synthesizer 11 generates a chirp signal over a frequency band designated by the controller 20 and outputs the chirp signal to the frequency filter 12. Here, it is assumed that the frequency synthesizer 11 generates a high-frequency chirp signal using an IF (intermediate frequency) signal and a local (local transmission) signal. Further, the frequency synthesizer 11 outputs a local signal to the reception mixer 43.

  The frequency filter 12 removes a predetermined frequency component contained in the chirp signal and outputs the obtained chirp signal to the pulse modulator 13. The pulse modulator 13 converts the chirp signal input from the frequency filter 12 into a transmission chirp pulse and outputs it to the high-power amplifier 14. The high-power amplifier 14 amplifies the intensity of the transmission chirp pulse input from the pulse modulator 13 and outputs it to the transmission / reception antenna 31. At this time, it is assumed that the transmission / reception switch 30 is connected to the high-power amplifier 14 and the transmission / reception antenna 31 so that the transmission chirp pulse is transmitted.

  When the transmission chirp pulse is transmitted, the transmission / reception switch 30 connects the transmission / reception antenna 31 to the frequency filter 41a and stands by. The reflected wave obtained by reflecting the transmission chirp pulse at the target is input to the frequency filter 41 a via the transmission / reception antenna 31. The frequency filter 41 a removes a predetermined frequency component from the reflected wave and outputs it to the low noise amplifier 42. The low noise amplifier 42 amplifies the input reflected wave and outputs it to the reception mixer 43. The reception mixer 43 converts the reception signal input from the low noise amplifier 42 into an IF signal using the local signal input from the frequency synthesizer 11. The reception mixer 43 outputs the obtained IF signal to the frequency filter 41b. The frequency filter 41 b removes a predetermined frequency component from the IF signal and outputs it to the duplexer 46. The duplexer 46 outputs the input IF signal to the A / D converter 47 (47a to 47c) according to the frequency band notified from the controller 20. The A / D converters 47 a to 47 c convert the input IF signal into digital data and output the digital data to the band interpolation processor 50.

  FIG. 3 is a diagram illustrating an example of the configuration of the band interpolation processor 50. The band interpolation processor 50 includes a buffer 51, a correction value table 52, an electrical length correction unit 53, and an interpolation processing unit 54. The buffer 51 stores the digital data input from the A / D converters 47a to 47c as a function of frequency. The correction value table 52 holds an electrical length correction value for each frequency band. The electrical length correction value is obtained in advance before the radar apparatus 10 is operated, and the correction value is recorded for each frequency. FIG. 4 shows an example of the correction value table 52. The electrical length correction unit 53 corrects the data stored in the buffer 51 using a correction value associated with the frequency at which the data was obtained. For example, the intensity of the signal at the frequency f1 is corrected to a value obtained by subtracting the correction value x1. Similarly, the electrical length correction unit 53 changes the intensity of the signal by subtracting a correction value corresponding to the frequency, and matches the phases of the plurality of received signals.

  The interpolation processing unit 54 performs band interpolation processing using the data corrected by the electrical length correction unit 53. First, the interpolation processing unit 54 combines the corrected data on the frequency axis. Further, data is obtained by band interpolation processing for frequencies for which data is not obtained. The interpolation processing unit 54 outputs the data obtained by the band interpolation processing to the signal processor 48 (FIG. 1). The signal processor 48 converts the input data into an impulse signal by converting it into a function of time using IFFT (inverse fast Fourier transform). Further, the signal processor 48 transforms the impulse signal into a format suitable for display on the display 49 and outputs it.

  FIG. 5 shows an example of the hardware configuration of the radar apparatus. As shown in FIG. 5, the radar apparatus 10 includes a control circuit 70, a display device 71, and a memory 72. The control circuit 70 implements the controller 20, the electrical length correction unit 53, the interpolation processing unit 54, and the signal processor 48. The control circuit 70 may be an arbitrary control circuit such as a CPU (Central Processing Unit) or an FPGA (Field-Programmable Gate Array). The memory 72 operates as the buffer 51 and further holds data such as the correction value table 52. The display device 71 operates as the display device 49.

<First Embodiment>
Hereinafter, an example of an operation performed in the first embodiment will be described. Note that the operation of the radar apparatus 10 may be changed depending on the implementation. For example, in the following example, a case is described in which transmission pulses of frequencies selected in order from the low frequency side are transmitted to the target 1 at regular intervals. However, the order of selecting frequency bands may be arbitrarily changed. Can do. Furthermore, in the following description, the received signals obtained from a plurality of transmission pulses are combined when they are recorded in the buffer 51. However, the combination of the received signals on the frequency axis is performed after the electrical length is corrected. It may be done in.

  (1) The controller 20 requests the frequency synthesizer 11 to transmit a chirp signal in the frequency band of f1 to f2, and the duplexer 46 further reflects the reflected wave of the signal in the frequency band of f1 to f2. Notify that. The transmission / reception switch 30 connects the high-power amplifier 14 and the transmission / reception antenna 31.

  (2) The frequency synthesizer 11 generates a chirp signal in the frequency band designated by the controller 20 using the IF signal and the local signal, and outputs the chirp signal to the frequency filter 12. Further, the frequency synthesizer 11 outputs the local signal used for generating the chirp signal to the reception mixer 43.

  (3) The frequency filter 12 removes a predetermined frequency component included in the chirp signal input from the frequency synthesizer 11, and generates a chirp signal in the frequency band of f1 to f2. The pulse modulator 13 converts the chirp signal input from the frequency filter 12 into a chirp pulse.

  (4) The high-power amplifier 14 amplifies the intensity of the chirp pulse input from the pulse modulator 13. The amplified chirp pulse is applied to the target 1 via the transmission / reception switch 30 and the transmission / reception antenna 31. For example, at time t1, the transmission / reception antenna 31 transmits the chirp pulse indicated by A in FIG. After the chirp pulse is transmitted, the transmission / reception switch 30 connects the transmission / reception antenna 31 and the frequency filter 41a.

  (5) When the time required for the radio wave to travel back and forth the distance from the radar device 10 to the target 1 has elapsed from the time t1, the transmission / reception antenna 31 reflects the reflected wave when the chirp pulses of f1 to f2 are reflected by the target 1. Receive. The reflected wave of the chirp pulse indicated by A in FIG. 6A is received by the transmitting / receiving antenna 31 with a delay of 2R / c from the time t1, as indicated by α in FIG. 6B. Here, R is the distance from the radar apparatus 10 to the target 1, and c is the speed of light. The transmitting / receiving antenna 31 outputs the received reflected wave to the frequency filter 41a. Moreover, when reception of the reflected wave of the chirp pulse is completed, the transmission / reception switch 30 switches the setting so that the high-power amplifier 14 and the transmission / reception antenna 31 are connected.

  (6) The frequency filter 41a outputs a signal adjusted to the frequency band of f1 to f2 by removing a predetermined frequency component included in the reflected wave α to the low noise amplifier 42. An example of the spectrum of the reflected wave α is shown by α in FIG. In addition, the horizontal axis of Fig.7 (a) is a frequency.

  (7) The reception mixer 43 converts the signal input from the low noise amplifier 42 into an IF signal using the local signal input from the frequency synthesizer 11. For example, the reflected wave α is converted into an IF signal in a frequency band of if1 to if2, as indicated by iα in FIG. 7B. The reception mixer 43 outputs the IF signal iα to the frequency filter 41b. The IF signal iα is adjusted again to the frequency band of if1 to if2 by the frequency filter 41b, amplified by the intermediate frequency amplifier 45, and output to the duplexer 46.

(8) The duplexer 46 outputs the input signal to any of the A / D converters 47a to 47c according to the frequency band notified from the controller 20. Here, the duplexer 46 is
IF signal output destination when transmission wave is f1 to f2: A / D converter 47a
IF signal output destination when transmission wave is f3 to f4: A / D converter 47b
IF signal output destination when transmission wave is f5 to f6: A / D converter 47c
Suppose that Therefore, the duplexer 46 outputs the signal input from the intermediate frequency amplifier 45 to the A / D converter 47a.

  (9) The A / D converter 47a converts the IF signal input from the duplexer 46 into an I / Q digital signal. The buffer 51 records the value of the I / Q digital signal input from the A / D converter 47a for each frequency. For example, the I / Q digital signal value is recorded in the buffer 51 in association with the frequency, such as (frequency, I / Q digital signal value) = (8.9 GHz, 0.75 + 0.6i). . Here, i is an imaginary unit. FIG. 8 is an example of a table held by the buffer.

  (10) When the output of the IF signal described in the procedure (8) is finished, the controller 20 requests the frequency synthesizer 11 to transmit a chirp signal in the frequency band of f3 to f4, and further sends to the duplexer 46 Notifies that the received signal is a reflected wave of a signal in the frequency band of f3 to f4. Then, chirp pulses of f3 to f4 are transmitted from the transmission / reception antenna 31 toward the target 1 at time t2 by the same processing as the procedures (2) to (4). The transmitted chirp pulse is shown in B of FIG.

  (11) The reflected wave β of the chirp pulse shown at B in FIG. 6A is received in the same manner as the procedures (5) and (6). An example of the spectrum of the reflected wave β is shown in β of FIG. Further, the reflected wave β is converted into an IF signal iβ in the frequency band of if3 to if4 as in the procedure (7). The spectrum of the IF signal iβ is indicated by iβ in FIG. The duplexer 46 outputs the IF signal iβ to the A / D converter 47b. The buffer 51 records the value of the I / Q digital signal input from the A / D converter 47b for each frequency.

  At this time, the buffer 51 couples the received wave obtained in the procedure (9) and the A / D converter 47b on the frequency axis. By this combination processing, the same frequency spectrum as when the data input from the A / D converter 47b and the data obtained in the procedure (9) are received at the same time is obtained. That is, the difference between the time t2 when the chirp pulse B is transmitted and the time t1 when the chirp pulse A is transmitted is corrected by the combining process. Here, in the following description, a case will be described in which t2−t1 = ΔT and the time t1 at which the chirp pulse A is transmitted is used as a reference. In this case, individual data included in the signal iβ obtained from the reflected wave of the chirp pulse B is regarded as data at a time earlier by ΔT than the actual reception time on the time axis.

  (12) Next, the controller 20 requests the frequency synthesizer 11 to transmit a chirp signal in the frequency band of f5 to f6, and further, the demultiplexer 46 receives a signal in the frequency band of f5 to f6. Notify that it is a reflected wave. Then, the chirp pulses of f5 to f6 are transmitted from the transmission / reception antenna 31 toward the target 1 at time t3 by the same processing as the procedures (2) to (4). The transmitted chirp pulse is shown at C in FIG.

  (13) The reflected wave γ of the chirp pulse shown at C in FIG. 6A is received in the same manner as the procedures (5) and (6). An example of the spectrum of the reflected wave γ is shown by γ in FIG. Further, the reflected wave γ is converted to an IF signal iγ in the frequency band of if5 to if6 in the same manner as in the procedure (7). The spectrum of the IF signal iγ is indicated by iγ in FIG. The duplexer 46 outputs the IF signal iγ to the A / D converter 47c. The buffer 51 records the value of the I / Q digital signal input from the A / D converter 47c for each frequency. Here, as described in the procedure (11), the individual data included in the IF signal iγ obtained from the reflected wave of the chirped pulse C is data at a time earlier by 2ΔT than the actual reception time on the time axis. It is considered. It is assumed that t3−t1 = 2ΔT.

  (14) When the value of the I / Q digital signal is recorded in the buffer 51 for each of the IF signals iα, iβ, and iγ, the electrical length correction unit 53 converts the numerical value recorded in the buffer 51 into the correction value table. 52 is used for correction. An example of processing of the electrical length correction unit 53 will be described with reference to FIG. The electrical length correction unit 53 acquires the correction value obtained for the frequency associated with the value of the I / Q digital signal from the correction value table 52. Furthermore, the electrical length correction unit 53 stores a value obtained by subtracting the acquired correction value from the value of the I / Q digital signal as the value of the corrected I / Q digital signal. For example, at 8.90 GHz, the value of the I / Q digital signal is 0.75 + 0.6i, and the correction value is a1 + b1i. Therefore, the electrical length correction unit 53 sets (0.75−a1) + (0.6−b1) i as a correction value. Correction is similarly performed for data of other frequencies.

  (15) The interpolation processing unit 54 performs band interpolation processing using the I / Q digital signal corrected by the electrical length correction unit 53. The method of the band interpolation process performed by the interpolation processing unit 54 is selected from any band interpolation technique. As shown in FIG. 7C, a spectrum extending from if1 to if6 is obtained by the band interpolation processing performed by the interpolation processing unit 54. The interpolation processing unit 54 outputs the obtained spectrum to the signal processor 48.

  (16) The signal processor 48 converts the spectrum input from the interpolation processing unit 54 into a function of time. Here, the spectrum input from the interpolation processing unit 54 to the signal processor 48 is a signal on the frequency axis as shown in FIG. 7C. Therefore, the signal processor 48 converts the frequency domain signal input from the interpolation processing unit 54 into a time domain signal. For example, when the signal processor 48 includes a digital filter, the signal processor 48 generates a time domain signal using the digital filter. The signal processor 48 can also generate a time domain signal by fast inverse Fourier transform.

  In the time domain signal obtained by the processing of the signal processor 48, a signal having a positive intensity at the time when the reflected wave is received is obtained. The transmission time of the chirp pulse A is time t1, the chirp pulse B is transmitted at time t2, and the chirp pulse C is transmitted at time t3. However, due to the coupling process on the frequency axis, as described in the procedures (11) and (13), the difference in transmission time is corrected before the band interpolation process. For this reason, the data obtained by the band interpolation can be regarded as data obtained by transmitting chirp pulses ranging from f1 to f6 transmitted at time t1, and can be expressed as a signal received by the radar apparatus 10 at the same time. Therefore, it becomes an impulse signal. That is, it can be said that the signal processor 48 generates an impulse signal by time-compressing the spectrum input from the interpolation processing unit 54. In the impulse signal obtained by the processing of the signal processor 48, the rising edge of the pulse is a time later than the time t1 by the time required for the radio wave to reciprocate between the radar apparatus 10 and the target 1. That is, the rise time of the impulse signal obtained by converting the result of band interpolation of the IF signals iα, iβ, iγ with the signal in the time domain can be expressed as t1 + 2R / c.

  (17) The signal processor 48 outputs the generated impulse signal to the display device 49. At this time, the signal processor 48 can also convert the impulse signal in accordance with the display performed on the display unit 49 and output the converted signal to the display unit 49. For example, when the measurement result is displayed on a graph with the distance to the target on the horizontal axis on the display 49, the signal processor 48 converts the impulse signal obtained as a function of time into a function of the distance and outputs it. . The horizontal axis is converted into a function of distance by integrating a value of half the speed of light on the horizontal axis.

In this case, the position at which the horizontal axis of the impulse signal is 0 is set as the chirp pulse transmission time as a reference when combining the spectra, and the value of the horizontal axis of the impulse signal is set to a value half the speed of light ( 1.5 × 10 ⁸ m / s) and the result of conversion is output to the display unit 49. Since the value of the horizontal axis of the pulse rising position in the time domain data is t1 + 2R / c, by setting t1 as the origin, the time from the origin to the pulse rising becomes 2R / c. Furthermore, the value on the horizontal axis of the rising edge of the pulse is (2R / c) × (c / 2) = R by integrating the value of half the speed of light on the horizontal axis. That is, a signal whose horizontal axis value of the rising edge of the pulse is the distance from the radar apparatus 10 to the target 1 is displayed on the display device 49. Therefore, the user can determine that the distance indicating the signal intensity higher than the threshold is the distance from the radar apparatus 10 to the target 1 in the graph converted into the distance function.

  (18) The frequency synthesizer 11 transmits the transmission chirp in the frequency band designated by the controller 20 while the reception signals obtained in the procedures (1) to (13) are processed by the processing after the procedure (14). The signal generation continues. Further, since the processing in the frequency filter 12, the pulse modulator 13, the high-power amplifier 14 and the like is also performed in the same manner as described above, the transmission pulse is transmitted at predetermined time intervals as shown in FIG. Are sent towards goal 1. Further, the frequency band included in the transmission pulse is changed at a predetermined timing. Further, the reflected wave from the target 1 is also received as shown in FIG. Using the received signal, the processes after (14) are repeated, and the radar apparatus 10 updates the distance to the target 1 based on the newly obtained data after band interpolation.

  In the above description, the case where the impulse signal is obtained by the processing of the signal processor 48 is taken as an example. However, the time domain signal may not be the impulse signal but may be a pulse having a width. In such a case, the distance from the rising position of the pulse to the target 1 may be obtained, or the distance to the target 1 may be obtained using a time that is ½ of the pulse width.

  FIG. 10 is a flowchart for explaining an example of the operation of the band interpolation processor 50. In the example of FIG. 10, received signals are combined after the electrical length is corrected. Therefore, it is assumed that the buffer 51 records a combination of the frequency and the value of the I / Q digital signal for each received signal. In FIG. 10, M is a constant representing the number of types of frequency bands of transmission pulses, and is an arbitrary integer of 2 or more. On the other hand, m is a variable used for counting the number of received signals whose electric length has been corrected.

  The electrical length correction unit 53 sets m = 1 (step S1). Next, the electrical length correction unit 53 acquires the value of the I / Q digital signal for each frequency for the mth received signal from the buffer 51 (step S2). Further, the electrical length correction unit 53 extracts the electrical length correction value for the same frequency as the received signal from the correction value table 52, and corrects the value of the I / Q digital signal with the correction value. (Steps S3 and S4). When the correction is completed for all the I / Q digital signal values obtained for the mth received signal, the electrical length correction unit 53 increments the value of m by one and compares it with M (steps S5 and S6). . When the value of m is less than or equal to M, the electrical length correction unit 53 repeats the processes after step S2. On the other hand, when the value of m exceeds M, the electrical length correction unit 53 notifies the interpolation processing unit 54 that the correction has been completed. Then, the interpolation processing unit 54 combines the plurality of reception signals by arranging the corrected reception signals for each frequency, and further performs band interpolation processing using the combined reception data (step S7). The interpolation processing unit 54 outputs the result of the band interpolation process to the signal processor 48, and ends the process (step S8).

  As described above, in the radar apparatus 10 according to the embodiment, the correction value for adjusting the phase can be obtained in advance as a function of the frequency by fixing the position where the plurality of transmission pulses are transmitted to the same position. it can. On the other hand, when correcting the difference in the phase of the radar signal without using the correction value obtained in advance, first, the singular point is obtained from the individual radar signals to be matched in phase, and the singular point obtained from both radar signals. The phase of the radar signal is corrected so that the phases of the signals are the same. Since the processing amount required for the processing for obtaining the singular point is large, the burden on the processing circuit included in the radar apparatus is large. Therefore, in the radar apparatus 10 according to the embodiment, it can be said that by matching the phase without obtaining the singular point, the load applied to the processing circuit when the phase of the received signal is adjusted is reduced.

  Further, since the phase of the two received signals can be matched using the correction value obtained in advance, the radar apparatus 10 obtains a singular point obtained from each radar signal in order to match the phase of the received signal. It is not necessary to perform the process. For this reason, the radar apparatus 10 can quickly obtain data used for band interpolation. Furthermore, since the band of the received signal can be expanded by band interpolation, even if the band of each transmitted wave actually transmitted / received is narrow, if the difference in frequency between the transmitted waves is large, the data up to the wide band can be used to reach the target. Can be measured. For example, the frequency band of the first transmission pulse is 4.0 GHz to 4.1 GHz, the frequency band of the second transmission pulse is 6.0 GHz to 6.1 GHz, and the frequency band of the third transmission pulse is 10.0 GHz. It is assumed that it is ˜10.1 GHz. Then, the same resolution as when the target 1 is irradiated with a pulse using a frequency band of 4.0 GHz to 10.1 GHz is realized by performing band interpolation on the reception signal obtained by the first to third transmission pulses. can do. Even in this case, the frequency band used for the actual transmission pulse is suppressed to 0.3 GHz in total.

<Second Embodiment>
In the first embodiment, the case where the frequency synthesizer 11 generates a transmission chirp signal has been described, but the chirp signal may be generated by the waveform generator 15. FIG. 11 shows an example of the configuration of the radar apparatus 60 according to the second embodiment. The radar device 60 includes a frequency synthesizer 61, a waveform generator 15, an intermediate frequency amplifier 16, and a frequency filter 12b. The waveform generator 15 generates a chirp signal and outputs it to the intermediate frequency amplifier 16. The intermediate frequency amplifier 16 outputs the amplified chirp signal to the frequency filter 12b. The amplified chirp signal is changed to a chirp signal of a predetermined frequency band by the frequency filter 12b, and then output to the transmission mixer 18.

  The radar device 60 further includes a controller 20, a frequency filter 12 a, a pulse modulator 13, a high output amplifier 14, a transmission / reception switch 30, and a transmission / reception antenna 31. The controller 20 determines the frequency of the local signal for generating the transmission pulse, and notifies the frequency synthesizer 61 and the duplexer 46 of the frequency. The method for determining the frequency of the local signal is determined according to a predetermined order as in the first embodiment. The frequency synthesizer 61 generates a local signal having a frequency notified from the controller 20 and outputs the local signal to the transmission mixer 18. The transmission mixer 18 generates a transmission chirp signal using the chirp signal input from the frequency filter 12 b and the local signal input from the frequency synthesizer 61. The operations of the frequency filter 12a, the pulse modulator 13, the high output amplifier 14, the transmission / reception switch 30 and the transmission / reception antenna 31 are the same as those in the first embodiment.

  Further, the radar apparatus 60 includes a frequency filter 41 (41a, 41b), a low noise amplifier 42, a reception mixer 43, an intermediate frequency amplifier 45, a duplexer 46, an A / D converter 47 (47a to 47c), and a signal processor. 48, a display 49, and a band interpolation processor 50. These operations are the same as those in the first embodiment.

<Third Embodiment>
FIG. 12 shows an example of the configuration of a radar apparatus 80 according to the third embodiment. The radar apparatus 80 changes the amplification amount of the transmission pulse according to the frequency component included in the transmission pulse so that the transmission pulse has a higher intensity as the transmission pulse has a higher frequency band.

  The radar device 80 includes a variable amplifier 81 and a controller 82. Further, the radar apparatus 80 generates a transmission wave by the frequency synthesizer 61, the frequency filters 12a and 12b, the pulse modulator 13, the high output amplifier 14, the waveform generator 15, the intermediate frequency amplifier 16, and the transmission mixer 18. Further, the transmission / reception switch 30 and the transmission / reception antenna 31 are used for transmission of transmission waves and reception of reception waves. The operations of the frequency filters 12a and 12b, the pulse modulator 13, the high power amplifier 14, the waveform generator 15, the intermediate frequency amplifier 16, the transmission mixer 18, the transmission / reception switch 30, and the transmission / reception antenna 31 are the first or second embodiment. It is the same. However, the high output amplifier 14 amplifies the chirp pulse input from the pulse modulator 13 and outputs the amplified chirp pulse to the variable amplifier 81. The radar apparatus 80 processes the received waves into frequency filters 41a and 41b, a low noise amplifier 42, a reception mixer 43, an intermediate frequency amplifier 45, a duplexer 46, an A / D converter 47, a band interpolation processor 50, a signal. The processing is performed by the processing unit 48 and the display unit 49. The received wave processing is the same as in the first or second embodiment.

  The controller 82 determines a frequency band to be used for generating a pulse according to the timing of generating a pulse by the same method as the controller 20 of the first embodiment. Further, the controller 82 notifies the variable amplifier 81, the frequency synthesizer 61, and the duplexer 46 of the frequency band used for generating the transmission pulse by the same method as the controller 20 of the first embodiment. Note that the controller 82 is realized by the control circuit 70.

  The variable amplifier 81 further amplifies the chirp pulse input from the high-power amplifier 14 with a gain stored in advance. FIG. 13 shows an example of the relationship between the frequency band and the gain. As shown in the table of FIG. 13, the variable amplifier 81 stores gain values for amplification for each frequency band. The operator can store the gain value determined according to the implementation in the variable amplifier 81. Since the attenuation in free space is larger in the high frequency band than in the low frequency region, the gain value is set to be larger as the frequency band is higher. The variable amplifier 81 amplifies the transmission pulse input from the high-power amplifier 14 with the gain stored in association with the frequency band. For example, in the example of FIG. 13, the gain at the time of amplification of the transmission pulse using the frequency band of f1 to f2 is 10 dB, and the gain at the time of amplification of the transmission pulse using the frequency band of f5 to f6 is 40 dB. The variable amplifier 81 transmits the amplified transmission pulse to the target 1 via the transmission / reception switch 30 and the transmission / reception antenna 31. FIG. 14A shows an example of a transmission wave transmitted from the radar apparatus 80. As shown in FIG. 14A, the intensity of the transmission pulse increases in the order of the transmission pulses f1 to f2, the transmission pulses f3 to f4, and the transmission pulses f5 to f6.

  FIG. 14B shows an example of a received wave received by the transmission / reception antenna 31 when the transmission wave of FIG. 14A is transmitted to the target 1. The attenuation in free space increases in the order of transmission pulses f1 to f2, transmission pulses f3 to f4, and transmission pulses f5 to f6. FIG. 14B shows an example of a received wave when the difference between the transmitted waves and the difference in attenuation amount due to the difference in frequency band are the same. As shown in FIG. 14B, when the intensity of the received pulse is approximately the same from f1 to f6, the maximum intensity of the received wave is also the received pulses of f1 to f2, f3 to f4 as shown in FIG. There is no significant difference between the three received pulses and the received pulses f5 to f6. An example of the frequency spectrum after the local signal is removed by the reception mixer 43 is shown in FIG. By removing the local signal, the spectrum of f1 to f2 is converted to the spectrum of if1 to if2. Similarly, the spectrum of f3 to f4 is converted to the spectrum of if3 to if4, and the spectrum of f5 to f6 is converted to the spectrum of if5 to if6.

  A result of amplification, A / D conversion, and the like performed on the converted spectrum is recorded in the buffer 51. The electrical length correction unit 53 corrects the electrical length, and the interpolation processing unit 54 performs band interpolation processing using the data after the electrical length correction. The spectrum obtained by the band interpolation process is shown in FIG.

  In this embodiment, it is possible to prevent the intensity of the reception wave from becoming weaker as the frequency becomes higher by increasing the transmission output as the transmission wave has a higher frequency. For this reason, it is possible to prevent deterioration in measurement accuracy due to the intensity of the received wave becoming weak at high frequencies. That is, the gain in the variable amplifier 81 is adjusted so that the intensity of the received wave can be maintained at a certain value or more regardless of the frequency, and the difference in attenuation in free space due to the frequency is included in the measurement result. The influence exerted can be reduced.

<Fourth Embodiment>
FIG. 15 is a diagram illustrating an example of the configuration of the radar device 90. The radar apparatus 90 can change the gain when a transmission pulse is amplified according to the distance from the received wave to the target 1. That is, in the fourth embodiment, the radar apparatus 90 recognizes the attenuation amount of the transmission wave using the fed back information and adjusts the gain when the transmission wave is amplified.

  The radar apparatus 90 includes a controller 91, a detector 92, a variable amplifier 93, and a distributor 94. In the radar apparatus 90, a transmission wave is generated by the waveform generator 15, the intermediate frequency amplifier 16, the frequency filters 12a and 12b, the transmission mixer 18, the frequency synthesizer 61, the pulse modulator 13, and the variable amplifier 93. The radar apparatus 90 includes a transmission / reception switch 30, a transmission / reception antenna 31, frequency filters 41a and 41b, a low noise amplifier 42, a reception mixer 43, an intermediate frequency amplifier 45, a duplexer 46, an A / D converter 47, and a band interpolation processor. 50, a signal processor 48, and a display 49 are also provided. Hereinafter, an example of the operation of the radar apparatus 90 will be described.

  (21) The controller 91 selects a frequency band to be used for the transmission wave by the same method as the controller 82 and notifies the frequency synthesizer 61 and the duplexer 46 of the selected frequency band. Further, the controller 91 determines a gain for each frequency band, and notifies the variable amplifier 93 of the determined gain. It is assumed that the value that is first notified from the controller 91 to the variable amplifier 93 is stored in advance by the controller 91.

  (22) The frequency synthesizer 61 generates a local signal in the frequency band notified from the controller 91 and outputs it to the transmission mixer 18 and the reception mixer 43. The operations of the waveform generator 15, the intermediate frequency amplifier 16, the frequency filters 12a and 12b, the transmission mixer 18, and the pulse modulator 13 are the same as those in the second embodiment. The pulse modulator 13 outputs the generated chirp pulse to the variable amplifier 93.

  (23) The variable amplifier 93 amplifies the pulse input from the pulse modulator 13 using the gain notified from the controller 91. The variable amplifier 93 transmits the amplified transmission pulse to the target 1 via the transmission / reception switch 30 and the transmission / reception antenna 31.

  (24) Operations of the transmission / reception antenna 31, the transmission / reception switch 30, the frequency filter 41a, and the low-noise amplifier 42 when receiving a received wave are the same as those in the first to third embodiments. However, the low noise amplifier 42 outputs the amplified signal to the distributor 94. The distributor 94 outputs the signal input from the low noise amplifier 42 to the reception mixer 43 and the detector 92.

  (25) The detector 92 outputs the intensity of the input signal to the controller 91. In the following example, the detector 92 includes a detection diode, and outputs a voltage corresponding to the power level input from the distributor 94 to the controller 91.

  (26) The controller 91 estimates the distance from the radar apparatus 90 to the target 1 based on the voltage value input from the detector 92. For example, the controller 91 can store a voltage table indicating the relationship between the distance from the radar device 90 to the target 1 and the voltage input from the detector 92 by a preliminary experiment or the like performed in advance. The controller 91 searches the voltage table using the voltage input from the detector 92 as a key, and obtains the distance from the radar device 90 to the target 1.

  (27) Next, the controller 91 calculates the attenuation amount of the transmission wave for each frequency band based on the distance from the radar device 90 to the target 1. Further, based on the calculation result, the gain for each frequency band is calculated so that the received pulse intensities in all frequency bands to be used are equal to or higher than the threshold. The controller 91 notifies the variable amplifier 93 of the gain obtained by the calculation in association with the frequency band.

  (28) The operations of the reception mixer 43, the frequency filter 41b, the intermediate frequency amplifier 45, the duplexer 46, the A / D converter 47, the band interpolation processor 50, the signal processor 48, and the display 49 are the first to the second operations. This is the same as the third embodiment.

  (29) The variable amplifier 93 amplifies the pulse input from the pulse modulator 13 using the gain notified from the controller 91. The variable amplifier 93 transmits the amplified transmission pulse to the target 1 via the transmission / reception switch 30 and the transmission / reception antenna 31. Thereafter, the processing after the procedure (24) is repeated.

  Next, a modified example of the radar apparatus 90 will be described. FIG. 16 is a diagram illustrating an example of the configuration of the radar device 95. The radar device 95 feeds back the result obtained by the signal processor 48 to the controller 96, so that the controller 96 calculates the gain at the variable amplifier 93.

  Operations of the waveform generator 15, the intermediate frequency amplifier 16, the frequency filters 12 a and 12 b, the transmission mixer 18, the frequency synthesizer 61, and the pulse modulator 13 provided in the radar device 95 are the same as those in the second embodiment. The variable amplifier 93 amplifies the transmission wave using the gain notified from the controller 96.

  The received wave processing performed by the radar device 95 and the method for obtaining the distance to the target 1 are the same as in the first to third embodiments. That is, when the received pulse obtained by the band interpolation process is converted into an impulse on the time axis, and the value of 1/2 of the speed of light is added to the value on the horizontal axis, the horizontal axis of the coordinates from which the impulse was obtained Is the distance between the radar device 95 and the target 1. The signal processor 48 notifies the controller 96 of the obtained distance. The controller 96 calculates the attenuation amount of the transmission wave for each frequency band based on the distance to the target 1. Further, based on the calculation result, the gain for each frequency band is calculated so that the received pulse intensities in all frequency bands to be used are equal to or higher than the threshold.

  Thus, the radar apparatus 90 can set the transmission power according to the distance to the target 1 by performing feedback. Further, the higher the frequency, the larger the atmospheric attenuation amount. Therefore, the radar apparatus 90 expects the difference in the attenuation amount, and the amplification of the variable amplifier at each frequency so that the received power at each frequency becomes equal. The amount can be varied.

<Fifth Embodiment>
In the fifth embodiment, the radar apparatus 10 is configured to secure a data amount when a region having a high frequency is used by making a chirp signal used for generating a transmission pulse having a high frequency band a wider band signal. The operation will be described.

  FIG. 17 shows an example of a table used for determining the frequency band and the pulse width. In the fifth embodiment, the controller 20 can determine the frequency band according to the table shown in FIG. In the table of FIG. 17A, the frequency band of the output transmission pulse and the amount of change in frequency at a predetermined time in the generated transmission pulse are recorded in association with the timing. The controller 20 determines the frequency band and the amount of change in the frequency in the pulse according to the number of pulses generated. For example, when the pulse number is one larger than a multiple of 3, the controller 20 sets the frequency band to f1 to f2 and sets the frequency change amount in the pulse to Δfa. When the pulse number is two times larger than a multiple of 3, the controller 20 sets the frequency band to f3 and f7 and changes the frequency Δfb, and when the pulse number is a multiple of 3, the frequency band is f5. At f8, the frequency change amount is set to Δfc. In the following description, it is assumed that the frequency increases in the order of f1 <f2 <f3 <f7 <f5 <f8. Further, the bandwidth is assumed to increase in the order of (f2-f1) <(f7-f3) <(f8-f5). Therefore, a chirp signal over a wider frequency band is used for higher-frequency transmission waves. Here, the pulse width is calculated from the following equation.

Pulse width = frequency bandwidth / frequency change amount per unit time in pulse Therefore, the pulse width can be calculated as follows, where n is an arbitrary integer of 0 or more.
(3n + 1) th generated pulse: (f2-f1) / Δfa
(3n + 2) th generated pulse: (f7−f3) / Δfb
3nth generated pulse: (f8−f5) / Δfc
Hereinafter, the pulse width is expressed as follows using τ1 to τ3.
τ1 = (f2−f1) / Δfa
τ2 = (f7−f3) / Δfb
τ3 = (f8−f5) / Δfc
Here, for easy understanding, it is assumed that the frequency change amount is the same value in any frequency band, that is, Δfa = Δfb = Δfc. Then, the frequency synthesizer 11 generates a chirp signal so that the length of the chirp signal becomes the signal of f1 to f2 <the signal of f3 to f7 <the signal of f5 to f8. The generated chirp signal is converted into a transmission pulse by the pulse modulator 13. At this time, since the pulse modulator 13 generates a transmission wave having a pulse width corresponding to the length of the chirp signal, τ1 <τ2 <τ3.

  FIG. 18A shows an example of a transmission wave transmitted from the radar apparatus 10. As shown in FIG. 18A, the transmission wave has a pulse width that increases in the order of transmission pulses f1 to f2, transmission pulses f3 to f7, and transmission pulses f5 to f8. FIG. 18B shows an example of a received wave received by the radar apparatus 10 when the transmitted wave of FIG. 18A is transmitted to the target 1. Since the attenuation in free space increases toward the high frequency side, the intensity of the received wave decreases in the order of the received waves of f1 to f2> received waves of f3 to f7> received waves of f5 to f8.

  The processing performed on the received wave is the same as in the first embodiment. An example of the spectrum of the received wave is shown in FIG. An example of the frequency spectrum after the local signal is removed by the reception mixer 43 is shown in FIG. By removing the local signal, the spectrum of f1 to f2 is converted to the spectrum of if1 to if2, the spectrum of f3 to f7 is converted to the spectrum of if3 to if7, and the spectrum of f5 to f8 is converted to the spectrum of if5 to if8. A result of amplification, A / D conversion, and the like performed on the converted spectrum is recorded in the buffer 51. The electrical length correction unit 53 corrects the electrical length, and the interpolation processing unit 54 performs band interpolation processing using the data after the electrical length correction. The spectrum obtained by the band interpolation process is shown in FIG.

Bandwidth may be expressed using specific bandwidth. Here, the ratio band is expressed as ratio band = bandwidth / center frequency. For this reason, even if it is the same ratio band as the low frequency on the high frequency side, the bandwidth can be widened, and it is expected that a wide frequency band can be secured relatively easily than the low frequency side. In this embodiment, the higher the frequency band, the wider the band that is used, so the amount of information obtained from the received wave in the high frequency band increases. Therefore, even if the amount of attenuation on the high frequency side is relatively large, deterioration of the accuracy of information obtained from the result on the high frequency side can be prevented by widening the band used at the high frequency.

  Next, a modification of this embodiment will be described. The controller 20 can also determine the frequency band according to the table shown in FIG. In this case, along with the frequency band, the controller 20 determines the pulse width of the transmission wave. The controller 20 notifies the pulse modulator 13 of the determined pulse width. Note that the radar apparatus 10 in which the table of FIG. 17B is used includes a signal line connecting the controller 20 and the pulse modulator 13, and the controller 20 applies a pulse to the pulse modulator 13 using the signal line. The width shall be notified. Furthermore, the controller 20 notifies the frequency synthesizer 11 of the frequency band. The frequency synthesizer 11 generates a chirp signal over the frequency band notified from the controller 20. The chirp signal is processed by the frequency filter 12 and then converted into a transmission pulse having a pulse width notified from the controller 20 in the pulse modulator 13.

<Modification>
The embodiment is not limited to the above, and can be variously modified. Some examples are described below.

FIG. 20 is an example of a transmission wave and a reception wave output from the radar apparatus 10. In the modification shown in FIG. 20, the radar apparatus 10 does not sequentially change the frequency of the transmission chirp pulse, but changes the frequency of the transmission chirp pulse every arbitrary predetermined time. For example, as shown in FIG. 20 (a), during the time _t 1 ~t _n is transmitted chirp pulse frequency f1~f2 is transmitted toward the target 1. Then, between times _t n + 1 _{~t 2n} are transmitted chirp pulse frequency F3～f4, between times _t 2n + 1 _{~t 3n} is transmitted chirp pulse frequency f5~f6 is transmitted toward the target 1. In this case, the processing until the received signal is input to the band interpolation processor 50 is the same as in the first embodiment. The band interpolation processor 50 does not start the process until the reception wave resulting from the transmission chirp pulse at the times t _{1 to} t _3n is received. When the data of 3n received waves is accumulated in the buffer 51, the electrical length correction unit 53 calculates an average value of n intensities for each frequency. The electrical length correction unit 53 corrects the electrical length using the numerical value recorded in the correction value table 52 with respect to the obtained average value. The electrical length correction unit 53 outputs data obtained by correcting the electrical length to the interpolation processing unit 54. Processing in the interpolation processing unit 54, the signal processor 48, and the display unit 49 is the same as that in the first embodiment. In this modification, since the frequency band of the transmission chirp pulse is changed every n pulses, the burden on the radar apparatus 10 when generating the transmission chirp pulse is reduced. Furthermore, since transmission chirp pulses of the same frequency band are used for a certain period of time, the detection accuracy of a stationary target or a target moving at a low speed can be improved.

  FIG. 21 shows an example of the configuration of the radar apparatus 100. The radar apparatus 100 performs band interpolation processing on the received RF signal. In the radar apparatus 100, the received RF signal is output to the demultiplexer 46 after passing through the frequency filter 41 a and the low noise amplifier 42. That is, the received RF signal is converted into a signal having a predetermined frequency component by the frequency filter 41 a, amplified by the low noise amplifier 42, and demultiplexed for each frequency band by the demultiplexer 46 controlled by the controller 20. The The received RF signal demultiplexed for each frequency band is converted into a digital signal by the A / D converter 47 (47a, 47b) corresponding to each frequency band. Further, band interpolation is performed by the band interpolation processor 50. The result obtained by the band interpolation is processed by the signal processor 48, and the obtained result is sent to the display unit 49. Thus, since the radar apparatus 100 performs band interpolation processing in the RF band, the reception mixer 43, the frequency filter 41b, and the intermediate frequency amplifier 45 may not be provided. For this reason, the radar apparatus 100 can have a relatively simple structure, and can be relatively easily reduced in size.

  FIG. 22 shows the configuration of the radar apparatus 110. The radar apparatus 110 includes a plurality of transmission antennas 111 (111a, 111b) and a reception antenna 112. In addition, although the example of FIG. 22 has shown the case where the number of the transmission antennas 111 is two, the number of the transmission antennas 111 may be changed arbitrarily according to mounting.

  In the radar apparatus 110, the transmission chirp signal generated by the frequency synthesizer 11 is demultiplexed for each frequency band by the demultiplexer 19, and is output to the frequency filter 12a or 12b associated with each frequency band. The chirp signal processed by the frequency filter 12a or the frequency filter 12b is converted into a pulse by the pulse modulator 13 (13a, 13b) and amplified by the high-power amplifier 14 (14a, 14b). The chirp pulse amplified by the high-power amplifier 14 is transmitted from the transmission antenna 111 (111a, 111b) toward the target 1. The timing at which the transmission chirp pulse of each frequency is transmitted is controlled by the controller 20 via the duplexer 19. On the other hand, the reception wave from the target 1 is received by the reception antenna 112. The received wave processing is the same as in the first embodiment. In such a modification, each transmitting antenna 111 can be an antenna corresponding to a narrow band, and thus the design of the radar apparatus 110 is facilitated. The correction value table 52 records the correction value of the electrical length when the transmission antenna 111 corresponding to each frequency band is used. For example, when transmission waves in the frequency band of f1 to f2 are transmitted from the transmission antenna 111a, the correction value used for the data in the frequency band of f1 to f2 is the electrical length when the transmission antenna 111a is used.

  FIG. 23 shows the configuration of the radar apparatus 120. The radar apparatus 110 includes a plurality of transmission antennas 111 (111a, 111b) and a plurality of reception antennas 112 (112a, 112b). The method of generating a transmission wave and the method of transmitting the transmission wave by the radar device 120 are the same as those of the radar device 110. The radar apparatus 120 receives a reception wave resulting from the transmission chirp pulse having the frequencies f1 to f2 reflected by the target by the reception antenna 112a. On the other hand, the reception wave due to the transmission chirp pulse having the frequencies f3 to f4 reflected by the target is received by the reception antenna 112b. The received signal is subjected to frequency band filtering, amplification, down-conversion, and digitization. The digitized data is recorded in the buffer 51. Subsequent processing is the same as in the first embodiment. Note that the number of transmission antennas 111 and reception antennas 112 is the same as the type of frequency band, and is arbitrarily changed.

  Although the case where the gain in the variable amplifier 93 is adjusted by feedback processing has been described in the fourth embodiment, the feedback processing can also be included in the fifth embodiment. In this case, the pulse width is adjusted by feedback processing. That is, the controller 20 can determine the pulse width according to the distance to the target 1, and can notify the pulse modulator 13 of the determined pulse width for each frequency band. The pulse modulator 13 generates a pulse so that the pulse width of the transmission chirp pulse becomes the pulse width notified from the controller 20.

  The fifth embodiment may be modified so that the controller 20 includes a table (the table shown in FIG. 17A) that is not Δfa = Δfb = Δfc. In this case, the controller 20 stores the frequency bandwidth and the amount of change in frequency in the table such that the pulse width increases as the transmission pulse has a higher frequency band, that is, τ1 <τ2 <τ3. .

  Furthermore, the above embodiments can be used in appropriate combination. For example, the radar devices 110 and 120 may be modified to generate a transmission chirp signal in the same manner as the radar device 60. Further, the radar devices 80, 90, and 95 may be modified to generate a transmission chirp signal in the same manner as the radar device 10.

1 Target 10, 60, 80, 90, 95, 100, 110, 120 Radar device 11, 61 Frequency synthesizer 12, 41 Frequency filter 13 Pulse modulator 14 High power amplifier 15 Waveform generator 16, 45 Intermediate frequency amplifier 18 Transmitter mixer 19, 46 Demultiplexer 20, 82, 91, 96 Controller 30 Transmission / reception switch 31 Transmission / reception antenna 42 Low noise amplifier 43 Reception mixer 47 A / D converter 48 Signal processor 49 Display 50 Band interpolation processor 51 Buffer 52 Correction value table 53 Electric length correction unit 54 Interpolation processing unit 70 Control circuit 71 Display device 72 Memory 81, 93 Variable amplifier 92 Detector 111 Transmitting antenna 112 Receiving antenna

Claims (8)

A transmitter for transmitting a first chirp pulse over a first frequency band and a second chirp pulse over a second frequency band different from the first frequency band toward a target to be observed;
A receiver that receives a first received signal that is a reflected wave of the first chirp pulse from the target, and a second received signal that is a reflected wave of the second chirp pulse;
A first correction spectrum is obtained by correcting the phase of the first reception signal with the correction value recorded in the correction value table, and the phase of the second reception signal is corrected with the correction value. A correction unit for obtaining a second correction spectrum by
By interpolating a signal between the first frequency band and the second frequency band to a signal obtained by combining the first and second correction spectra, the second frequency band is interpolated from the first frequency band. A band interpolation processing unit that generates an interpolation signal representing a reflected wave obtained when the target is irradiated with a chirp signal up to a frequency band of
A radar apparatus comprising: a signal processing unit that obtains a distance to the target using the interpolation signal. The correction value table includes a correction value for eliminating a change in phase that occurs due to an electrical length through which the first and second chirp pulses are transmitted toward the target. Record as a function of the frequency of the signal going through the length,
The correction unit obtains the first and second correction spectra by correcting the first and second received signals using a correction value associated with the same frequency as the signal to be corrected. The radar apparatus according to claim 1. The correction unit obtains the first correction spectrum without obtaining the first singular point, which is the frequency component of the scattering center of the first chirp pulse at the target, from the first received signal; The second correction spectrum is obtained without obtaining the second singular point, which is the frequency component of the scattering center of the second chirp pulse at the target, from the second received signal. Item 3. The radar device according to item 1 or 2. An amplifier for amplifying the intensity of the first and second chirp pulses;
The said amplifier amplifies the intensity | strength of a chirp pulse so that the transmission intensity | strength of the chirp pulse transmitted may become so high that the frequency contained in the chirp pulse to be amplified is high. The radar device described in 1. By estimating the attenuation amount for each frequency from the distance calculated by the signal processing unit, a first gain when amplifying the chirp pulse over the first frequency band and a chirp pulse over the second frequency band are obtained. A control unit for obtaining a second gain for amplification;
The control unit notifies the amplifier of the first gain in association with the first frequency band, and notifies the amplifier of the second gain in association with the second frequency band,
The amplifier amplifies a third chirp pulse over the first frequency band with the first gain, and amplifies a fourth chirp pulse over the second frequency band with the second gain. The radar apparatus according to claim 4. A pulse modulator for generating the first chirp pulse from the chirp signal over the first frequency band and generating the second chirp pulse from the chirp signal over the second frequency band;
The radar according to any one of claims 1 to 3, wherein the pulse modulator generates a chirp pulse such that the higher the frequency included in the signal used for generating the chirp pulse, the wider the pulse width. apparatus. The first pulse width applied to the chirp pulse over the first frequency band and the chirp pulse over the second frequency band are estimated by estimating the attenuation amount for each frequency from the distance calculated by the signal processing unit. A control unit for obtaining a second pulse width to be
The control unit notifies the pulse modulator of the first pulse width in association with the first frequency band, and associates the second pulse width with the second frequency band of the pulse. Notify the modulator,
The pulse modulator adjusts a third chirp pulse over the first frequency band to the first pulse width, and adjusts a fourth chirp pulse over the second frequency band to the second pulse width. The radar apparatus according to claim 6. Transmitting a first chirp pulse over a first frequency band and a second chirp pulse over a second frequency band different from the first frequency band toward a target to be observed;
Receiving a first received signal that is a reflected wave of the first chirp pulse from the target and a second received signal that is a reflected wave of the second chirp pulse;
A first correction spectrum is obtained by correcting the phase of the first reception signal with the correction value recorded in the correction value table, and the phase of the second reception signal is corrected with the correction value. To obtain the second corrected spectrum,
By interpolating a signal between the first frequency band and the second frequency band to a signal obtained by combining the first and second correction spectra, the second frequency band is interpolated from the first frequency band. Generating an interpolated signal representing a reflected wave obtained when the target is irradiated with a chirp signal up to a frequency band of
A method for detecting a target, comprising: obtaining a distance to the target using the interpolation signal.

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