JP6962692B2 - Radar device - Google Patents

Description

The present invention relates to a radar device using radio waves, and more particularly to a radar device having a transmitting unit that periodically transmits radio waves for exploration.

As a radar device, it transmits radio waves toward the ground as a transmission signal, receives reflected waves from buried objects in the ground, and correlates the received signal due to reflection with a reference signal that gives a time lag to the transmission signal. Medium radar devices are known (see, for example, Patent Document 1). In the apparatus of Patent Document 1, the influence of disturbance noise is reduced by the correlation processing. Further, in the device of Patent Document 1, a chirp signal is used as a radio wave transmitted to the ground, and the search depth is deepened while ensuring the resolution.

However, even with the radar device of Patent Document 1, it is not easy to reduce the influence of disturbance caused by noise sources such as various radios.

Japanese Unexamined Patent Publication No. 2016-90297

The present invention has been made in view of the above background technology, and an object of the present invention is to provide a radar device in which the influence of disturbance caused by a noise source is reduced and the signal detection capability is enhanced.

Radar devices for achieving the above objectives include a transmitter that periodically transmits radio waves for exploration, a receiver that receives radio waves in synchronization with the radio waves for exploration, and a target state based on the received radio waves. It is provided with a control unit that detects the above and changes the repetition cycle of the radio wave transmitted from the transmission unit.

In the radar device, since the control unit changes the repetition period of the radio wave transmitted from the transmission unit, it is possible to prevent the frequency of the radio wave to be transmitted and the specific frequency from the noise source from matching or superimposing, and the noise source. It is possible to enhance the signal detection ability by suppressing the interference with the radio waves.

In a specific aspect of the present invention, in the radar device, the control unit causes the receiving unit to receive radio waves while changing the repetition period within a predetermined range, and the noise level of the received radio waves is equal to or less than a predetermined allowable value. In this case, the transmitting unit is made to perform the radio wave transmission operation at the repetition cycle corresponding to the noise level equal to or less than the predetermined allowable value, and the receiving unit is made to perform the operation synchronized with the transmitting unit. In this case, it is possible to make adjustments while changing the repetition period until the noise level becomes sufficiently low by preliminary measurement, and the influence of the noise source can be surely suppressed.

In another aspect of the present invention, the control unit causes the receiving unit to receive radio waves while changing the repeating cycle within a predetermined range, and transmits radio waves to the transmitting unit at the repeating cycle in which the noise level of the received radio waves is the lowest. And make the receiving unit perform the operation synchronized with the transmitting unit. In this case, it is possible to select the repetition period having the lowest noise level while changing the repetition period by preliminary measurement, and it is possible to surely suppress the influence of the noise source.

In yet another aspect of the present invention, the control unit causes the transmitting unit to perform a transmission operation while changing the repetition period of radio waves within a predetermined range, and causes the receiving unit to perform an operation synchronized with the transmitting unit. In this case, the preliminary measurement for searching for an appropriate repetition period becomes unnecessary, and the measurement can be started quickly. Further, even when the frequency of the noise source fluctuates, the noise level can be suppressed according to such fluctuation.

In yet another aspect of the present invention, the control unit extracts information in the depth direction (for example, the depth direction) using a radio wave having a noise level of a predetermined allowable value or less or a radio wave having the lowest noise level.

Yet another aspect of the invention is to change the repetition period to discrete values with a predetermined step size. In this case, it is possible to efficiently cover the repetition period in which the noise level is sufficiently low, and it is possible to perform highly accurate measurement.

In yet another aspect of the present invention, the control unit changes the repetition period with a random amount of change. In this case, it is possible to easily suppress the tendency to pick up a large amount of noise in the measurement of a certain point or depth and its surroundings, and it becomes easy to efficiently measure the target without omission.

In yet another aspect of the present invention, the radio waves transmitted periodically have a pulse-like waveform or a chirp-like waveform having no carrier wave component. In this case, it becomes easy to intermittently limit the transmission timing of radio waves.

In yet another aspect of the present invention, the state of interest is detected by a sampling method using a reference signal or a correlation method. In this case, the S / N ratio of the measured value can be increased.

In yet another aspect of the present invention, the transmitting unit periodically transmits radio waves for ground penetrating radar, and the receiving unit receives radio waves in synchronization with the radio waves for ground penetrating radar.

It is a block diagram explaining the radar apparatus which concerns on 1st Embodiment. (A) to (C) are diagrams for explaining a transmitted wave. (A) and (B) are diagrams for explaining the frequency pattern of the transmitted wave. (A) and (B) are diagrams for explaining the relationship between the transmitted wave and noise. It is a conceptual diagram explaining the operation of the radar apparatus of FIG. It is a conceptual diagram explaining the operation of the modification. (A) to (D) are diagrams for explaining the transmitted wave formed by the radar device according to the second embodiment. (A) shows an example of a response wave, and (B) shows an example of a response wave disturbed by a noise signal. (C) and (D) show a response wave partially disturbed by noise. It is a conceptual diagram explaining the operation of the radar apparatus of 2nd Embodiment.

[First Embodiment]
Hereinafter, the radar device 100 of the first embodiment according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, the radar device 100 is for ground penetrating radar, and includes a radar signal generator 10, a transmitting amplifier 21, a transmitting antenna 31, a receiving antenna 32, a receiving amplifier 22, and a receiving amplifier 22. It includes a correlation processing unit 40, a noise evaluation processing unit 50, a timing control unit 70, a main control unit 80, and a display unit 90. The radar device 100 can be mounted on a moving body such as an automobile or a train.

Among the radar devices 100, the radar signal generation unit 10, the correlation processing unit 40, the noise evaluation processing unit 50, the timing control unit 70, and the main control unit 80 determine the target state based on the response wave S2 which is the received radio wave. A control unit 101 for performing an operation such as detection is configured.

The radar signal generation unit 10 generates a pulsed transmission wave SP under the control of the timing control unit 70. More specifically, the radar signal generation unit 10 intermittently outputs a pulse-shaped or chirp-shaped transmitted wave SP at a predetermined period. The radar signal generator 10 includes a pulse signal generator or a chirp signal generator.

The transmission amplifier 21 amplifies the transmission wave SP formed by the radar signal generation unit 10, and the transmission antenna 31 is driven by the transmission amplifier 21 to radiate the transmission wave S1 as a radio wave toward the ground. The transmitted wave S1 radiated from the transmitting antenna 31 corresponds to the transmitted wave SP or the exploration wave GS generated by the radar signal generation unit 10. The radar signal generation unit 10, the transmission amplifier 21, and the transmission antenna 31 function as a transmission unit 20a that periodically transmits radio waves for ground penetrating radar.

FIG. 2A conceptually shows the transmitted wave SP output from the radar signal generation unit 10. The signal output from the radar signal generation unit 10 or the like has no carrier wave component and is composed of a group of periodic transmission wave SPs. A group of periodic transmission wave SPs is repeated a predetermined number of times in a repetition period Ts, and is output as a set of exploration wave GS from the radar signal generation unit 10 in a state where the radar device 100 exists at a specific point. .. The number of transmitted wave SPs included in the exploration wave GS is set according to the target exploration depth and sensitivity. 2 (B) and 2 (C) exemplify a specific waveform of the transmitted wave SP, and in the case shown in FIG. 2 (B), the transmitted wave SP is, for example, a pulse of 1 nS or 3 nS. In the case shown in 2 (C), the transmitted wave SP is a chirp formed of, for example, a high frequency component of 50 MHz to 800 MHz. Although the waveform of the transmission wave SP output from the radar signal generation unit 10 has been described above, the transmission wave (radio wave) S1 output from the transmission antenna 31 also has the same waveform.

The receiving antenna 32 is arranged adjacent to the transmitting antenna 31 and receives the response wave S2 which is a radio wave reflected and returned by the buried object or other exploration object OB existing in the underground UG which is the object of the exploration. Then, the receiving amplifier 22 amplifies the signal corresponding to the response wave S2 received by the receiving antenna 32 and outputs it as the response wave SR. The receiving antenna 32, the receiving amplifier 22, and the correlation processing unit 40 function as a receiving unit 20b that receives radio waves in synchronization with the radio waves for ground penetrating radar.

The correlation processing unit 40 uses the digital or analog reference signal S3 corresponding to the transmission wave SP formed by the radar signal generation unit 10 for the response wave SR received by the reception antenna 32 and amplified by the reception amplifier 22. , Correlation processing is performed while shifting the timing of the reference signal S3, and a signal component having a high correlation with the transmission wave SP is sampled or extracted from the response wave SR. As a result, the correlation processing unit 40 has a cross-correlation between the transmission wave SP and the response wave SR. The signal component obtained by the correlation processing unit 40 is output in association with the distance in the depth direction (specifically, the depth direction) corresponding to the timing difference (hereinafter, also referred to as delay time) from the reference signal S3. That is, the signal output S5 of the correlation processing unit 40 is measurement data obtained by calculating the amplitude of the signal component obtained from the response wave SR for each distance in the depth direction. The correlation processing unit 40 includes an A / D converter, a weighting filter, and the like, in addition to a correlator that performs correlation processing on the response wave SR and the reference signal S3. The weighting filter weights the response wave SR according to the delay time, and for example, STC (sensitivity time control) can be used. By using STC, it is possible to correct the influence of reflection on the ground surface and attenuation in the depth direction.

The noise evaluation processing unit 50 evaluates the noise level based on the signal output S5 obtained by performing the correlation processing in the correlation processing unit 40 and the response wave SR before the correlation processing. Specifically, the energy intensity of the signal output S5 or the response wave SR is calculated, and when this energy intensity exceeds a predetermined threshold value, the noise level exceeds the permissible value and the signal output S5 or the response wave SR becomes noise. Judge that there is a high possibility of being buried. The noise evaluation is not limited to the method using the energy intensity of the signal as described above, but various methods using the envelope pattern or the like can be used.

The timing control unit 70 operates under the control of the main control unit 80, and adjusts the timing at which the transmission wave SP is output from the radar signal generation unit 10. Specifically, the timing control unit 70 sets the output start timing of the transmission wave SP or the exploration wave GS and the repetition cycle of the transmission wave SP by the trigger signal S7 output to the radar signal generation unit 10. The trigger signal S7 is composed of a group of signal portions arranged in time series, a group of periodic transmission wave SPs is generated from the radar signal generation unit 10, and the transmission wave S1 is radiated from the transmission antenna 31. When the exploration object OB exists as an abnormal point in the underground UG, a group of periodic transmission waves S1 and a group of response waves S2 and SR as a periodic amplitude waveform synchronized with the SP are generated, and the exploration object is explored. Enables measurement of the distance to the OB.

Although not shown, the timing control unit 70 includes a GPS receiver, a speedometer, an accelerometer, and the like, and controls the trigger signal S7 while monitoring the position of the transmitting antenna 31 and the like. As a result, the movement path of the radar device 100 can be grasped, and each time the radar device 100 moves a predetermined distance, the timing control unit 70 outputs a trigger signal S7 composed of a group of signal parts, and the radar signal generation unit 10 outputs a trigger signal S7. A set of exploration wave GS is output, and it is possible to measure the distance to the exploration object OB existing in the underground UG at the measurement point.

The main control unit 80 manages the operations of the noise evaluation processing unit 50, the timing control unit 70, and the like. Further, the main control unit 80 processes the signal output output from the correlation processing unit 40 to create search information suitable for visualization. That is, the main control unit 80 creates search information based on the signal output output from the correlation processing unit 40 and the position information of the radar device 100, and displays the search information on the display unit 90. In the exploration information created by the main control unit 80, for example, the vertical axis is the depth, the horizontal axis is the position or the moving distance along the moving path of the radar device 100, and each coordinate point defined by the vertical axis and the horizontal axis is set. On the other hand, the absolute value of the amplitude of the signal output S5 of the correlation processing unit 40 is associated with it.

The display unit 90 operates under the control of the main control unit 80 and displays the information created by the main control unit 80. Specifically, the display unit 90 receives the exploration information processed by the main control unit 80 based on the signal component output from the correlation processing unit 40 and performs the corresponding display. The exploration information displayed by the display unit 90 is a tomographic map showing the state in the ground in a two-dimensional distribution in the depth direction and along the movement path.

Hereinafter, the operating principle of the radar device 100 of the first embodiment shown in FIG. 1 will be described.

FIG. 3A shows a frequency spectrum of a single transmitted wave SP output from the radar signal generation unit 10. The dotted line in the chart shows the frequency spectrum of the 1 nS pulse as shown in FIG. 2 (B), and is spread over a wide frequency band of 0 to 1000 MHz due to having a pulse width of 1 nS. The alternate long and short dash line in the chart shows the frequency spectrum of the chirp as shown in FIG. 2C, and extends over a wide frequency band of 50 MHz to 800 MHz corresponding to the change in the frequency of 50 MHz to 800 MHz. Regardless of whether the transmitted wave SP is a pulse or a charp, the transmitted wave SP extends over a wide frequency band, and 27 MHz CB radio, 140 MHz to 160 MHz amateur simple radio, and 207 MHz to 220 MHz existing in this wide frequency band. There is a possibility of interfering with radio waves from noise sources NS such as multimedia broadcasting and 430 MHz amateur radio.

FIG. 3B is an enlarged view of the frequency spectrum shown in FIG. 3A in the frequency direction, and the transmitted wave SP is composed of a large number of discrete spectral peak DPs arranged at equal intervals in the frequency direction. ing. Here, the frequency interval Δf corresponds to the reciprocal of the repetition period Ts of the transmitted wave SP as shown in FIG. 2 (A), and when Ts = 1 μS, Δf = 1 / Ts = 1 MHz, so that the transmission is transmitted. When the wave SP is, for example, a 1 nS pulse, the transmitted wave SP has a spectral pattern consisting of discrete spectral peak DPs such as ..., 100 MHz, 101 MHz, 102 MHz, ..., 400 MHz, 401 MHz, 402 MHz, ... .. In the above example, when Ts = 0.5 μS, Δf = 2 MHz, so that the transmitted wave SP is composed of spectral peak DPs such as ..., 100 MHz, 102 MHz, 104 MHz, ..., 400 MHz, 402 MHz, 404 MHz, and so on. It has a spectral pattern. When the transmitted wave SP is a chirp, the discrete spectral peak DPs arranged at equal intervals appear only in the frequency band of the chirp (for example, 50 MHz to 800 MHz).

4 (A) and 4 (B) are conceptual diagrams illustrating a method of avoiding interference with the noise source NS by increasing or decreasing the repetition period Ts of the transmitted wave SP. FIG. 4A shows a case where the repetition period Ts is 1 μS, and FIG. 4B shows a case where the repetition period Ts is 1.025 μS. In the case of FIG. 4A, the spectrum peak DP of the transmission wave SP and the noise signal NZ from the noise source NS are superimposed, and the response wave SR is generated by the radio waves from the noise source NS such as amateur radio. Detection is disturbed. On the other hand, in the case of FIG. 4B, the spectrum peak DP of the transmission wave SP and the noise signal NZ from the noise source NS are in a deviated state, and the response wave is caused by radio waves from the noise source NS such as amateur radio. SR detection is not disturbed. Here, when the repetition period Ts of the transmission wave SP is 1.025 μS, the frequency interval Δf is 0.975 MHz, and the spectrum peak DP is (1 / 1.025) MHz × 307 = 299.5 MHz, (1). /1.025) MHz × 308 = 300.5 MHz, and the noise signal NZ is located in the middle of a pair of adjacent spectral peak DPs. By slightly increasing or decreasing the repetition period Ts of the transmission wave SP in this way, if the noise signal NZ has a narrow band, it is possible to easily avoid interference with the transmission wave SP.

Hereinafter, an operation example of the radar device 100 will be described with reference to FIG. First, the main control unit 80 operates only the reception function (step S11). That is, the timing control unit 70 operates the radar signal generation unit 10, but prevents the transmission wave S1 from being output from the transmission antenna 31. At this time, the radar signal generation unit 10 generates the transmission wave SP in the default repetition cycle, and this transmission wave SP is used as the reference signal S3 for the correlation processing unit 40.

Next, noise evaluation is performed using the noise evaluation processing unit 50 (step S12). Specifically, the noise evaluation processing unit 50 calculates the noise level as an evaluation value from the signal output S5 of the correlation processing unit 40, and the main control unit 80 takes in the noise level value output by the noise evaluation processing unit 50. ..

Next, the main control unit 80 determines whether or not the noise level obtained in step S12 is equal to or less than a predetermined allowable value (step S13). Normally, when the transmission wave S1 does not exist, the noise level value obtained in step S12 becomes the noise floor of the receiving unit 20b. However, when a noise source NS exists in the vicinity and a strong noise signal NZ is output, the value of the noise level obtained in step S12 exceeds the permissible value.

When it is determined in step S13 that the noise level exceeds a predetermined allowable value, the main control unit 80 transmits by the timing control unit 70 unless the evaluation in all the repetition periods Ts is completed (N in step S14). For example, the repetition period Ts of the wave SP is gradually increased or decreased with a predetermined step size, or is randomly increased or decreased with a predetermined step size (step S15).

When the repetition period Ts is changed with a predetermined step size, the default step size is a step width that can be said to be the smallest unit, for example, at the maximum frequency of the spectral peak DP, one or more frequencies of interest, or the minimum frequency. The frequency interval Δf of adjacent spectral peak DPs is divided into k (natural number) sections so that the spectral peak DPs appear at k-1 frequency positions that gradually increase or decrease. However, if the minimum step width is equal to or less than the half width of the target spectrum peak DP, the spectrum peak DP cannot be substantially shifted, and the change of the repetition period Ts becomes meaningless. When the repetition period Ts is changed by a predetermined step size, the range of the upper limit and the lower limit for changing the repetition period Ts also becomes a problem. If the amount of change is large, the burden of measurement and arithmetic processing increases, while if the amount of change is small, the possibility that noise cannot be removed increases.

On the other hand, when it is determined in step S13 that the noise level is equal to or less than the predetermined allowable value, the transmission operation and the reception operation are performed in the repetition cycle Ts determined to be equal to or less than the allowable value in step S13. That is, a normal search operation is performed under the control of the main control unit 80 (step S16). Specifically, the main control unit 80 operates the radar signal generation unit 10 with a repetition period Ts that can suppress noise to a predetermined value or less, and the correlation processing unit 80 is in a state where the transmission wave S1 is output from the transmission antenna 31. The signal output S5 of 40 is taken in as measurement data. The signal output S5 of the correlation processing unit 40 associates the distance (delay time) in the depth direction with the response intensity at the measurement point, and accumulates this along the movement path of the radar device 100. For example, it is possible to obtain a tomographic map showing the state in the ground in a two-dimensional distribution in the depth direction and along the movement path.

When the evaluation in all the repetition cycles Ts is completed (Y in step S14), the noise level may not be less than the predetermined allowable value. Therefore, the main control unit 80 displays an error on the display unit 90. The user is asked to decide whether to end or continue the process (step S17).

Hereinafter, another operation example of the radar device 100 will be described with reference to FIG. First, the main control unit 80 operates only the receiving function (step S21). That is, the timing control unit 70 operates the radar signal generation unit 10, but prevents the transmission wave S1 from being output from the transmission antenna 31. At this time, the noise evaluation processing unit 50 is operating.

Next, the main control unit 80 determines whether or not the repetition period Ts of the transmission wave SP is changed within a predetermined range and the change of the period is completed (step S22).

When the change of the repetition cycle Ts is not completed within a predetermined range, the timing control unit 70 changes the repetition cycle Ts of the transmitted wave SP to the next repetition cycle Ts (step S23). Here, the predetermined type range means a plurality of sets of repetition periods Ts determined in advance, and is obtained by increasing or decreasing an appropriate difference with respect to the basic period Ts0 which is the basic repetition period of the transmitted wave SP. There is. Specifically, for example, assuming that the basic period Ts0 = 1 μS, the repetition period Ts is as small as 0.925 μS, 0.95 μS, 0.975 μS, 1.025 μS, 1.05 μS, 1.075 μS, and within a narrow range. To change.

Next, the main control unit 80 performs noise evaluation by taking in a group of noise level values accumulated in the noise evaluation processing unit 50 (step S24). Here, the value of the noise level as the noise evaluation is accumulated as many times as the number of times including the basic period Ts0 which is the original repetition period and the repetition period Ts changed within a predetermined kind range.

Next, the main control unit 80 selects the best period among the noise levels captured in step S24 (step S25). That is, the main control unit 80 sets the repetition period Ts at which the noise level is the lowest as the best period.

Next, the main control unit 80 performs a transmission operation and a reception operation in the repetition cycle Ts which is the best in step S25. That is, a normal search operation is performed under the control of the main control unit 80 (step S26).

As described above, in the radar device 100 of the first embodiment, since the main control unit 80 changes the repetition period Ts of the transmission wave S1 as the radio wave transmitted from the transmission unit 20a, the frequency of the transmission wave S1 radio wave to be transmitted and the frequency of the transmission wave S1 radio wave are changed. It is possible to prevent the specific frequencies from the noise source NS from matching or superimposing with each other, and it is possible to suppress the interference of the noise source NS with the radio waves and enhance the signal detection capability.

[Second Embodiment]
Hereinafter, the radar device of the second embodiment will be described. The radar device of the second embodiment is a modification of the radar device 100 of the first embodiment shown in FIG. 1 and the like, and duplicate description will be omitted for the same parts. The radar device of the second embodiment aims to avoid a collision with a noise signal by changing the repetition period within a certain range like a pseudo noise distribution when searching for the same measurement point.

FIG. 7A shows a plurality of exploration waves GS1, GS2, GS3, ... Output from the radar signal generation unit 10, and the individual exploration waves GS1, GS2, GS3, ... Used. The exploration wave GS1 is composed of three or more regions R1, R2, R3, ... (See FIGS. 7 (B) to 7 (D)). The repetition period of each region R1, R2, R3, ... Is discrete, and an appropriate difference is increased or decreased with respect to the basic repetition period of the transmitted wave SP. Specifically, for example, when the basic period Ts0 = 1 μS corresponding to the basic repetition period, the region R1 has a repetition period Ts = T1 of 0.925 μS, and the region R2 has a repetition period Ts = T2 of 1 μS. In the region R3, the repetition period Ts = T3 is 1.075 μS. That is, the repetition period Ts of each region R1, R2, R3, ... Is different with a constant step width of 0.075 μS. The next exploration wave GS2 also consists of three or more regions R1, R2, R3, ..., But the repetition period Ts of these regions R1, R2, R3, ... Is different from that of the previous exploration wave GS1. ing. That is, the cycles such as 0.925 μS, 1 μS, and 1.075 μS are randomly replaced. The same applies to the next exploration wave GS3. As a result, when there is a disturbance due to the noise signal NZ, a discontinuous phenomenon occurs in which only the region R2 interferes with the noise in the exploration wave GS1 and only the region R1 interferes with the noise in the exploration wave GS2.

FIG. 8A shows an example of the response wave SR pattern, and FIG. 8B shows an example of the response wave SR disturbed by the noise signal NZ. The pattern of FIG. 8A has a surface reflection portion P1 and a plurality of reflection waveforms P2. The surface reflective portion P1 is removed by STC or other filtering. The reflected waveform P2 remains even after filtering, indicating the presence of cavities and pipes in the ground.

FIG. 8C shows the response wave SR obtained by the exploration wave GS1. In this case, only the regions R3 shown in FIGS. 7 (A) and 7 (D) interfere with the noise, and the noise appears in one region A3 of the response wave SR, but the noise appears in the other regions A1 and A2. Has not appeared. FIG. 8D shows the response wave SR obtained by the exploration wave GS2 corresponding to the next measurement point. In this case, only the regions R2 shown in FIGS. 7 (A) and 7 (C) interfere with the noise, and the noise appears in one region A2 of the response wave SR, but the noise appears in the other regions A1 and A3. Has not appeared. In this way, even if disturbance is caused by the reception of the noise signal NZ, the region where noise is generated in the response wave SR moves between the regions A1, A2, A3, ... Every time the measurement point moves sequentially. It changes randomly. As a result, it is possible to prevent the signal output S5 of the normal correlation processing unit 40 or the measurement data from being lost due to being biased to a specific depth or depth, and it is possible to avoid noise in the overall exploration information (two-dimensional tomographic map, etc.). The impact can be dispersed.

In the above example, each exploration wave GS1, GS2, GS3, ... Is divided into a plurality of regions R1, R2, R3, ... The repetition period Ts that changes randomly in the group is assigned, but the repetition period Ts is assigned in units of exploration waves. Specifically, the repetition period Ts that changes randomly in the numerical group that increases or decreases in a predetermined step size is assigned. It can also be assigned to each exploration wave GS1, GS2, GS3, ... In this case, it interferes with the noise signal NZ in units of measurement points, and there are places in the series of measurement points where normal measurement data cannot be obtained due to the influence of noise, but the places where measurement data cannot be obtained are random. The influence of noise can be dispersed in the entire exploration information (two-dimensional tomographic map, etc.).

Hereinafter, an operation example of the radar device 100 of the second embodiment will be described with reference to FIG. First, the search operation is performed under the control of the main control unit 80 (step S31). Specifically, the main control unit 80 operates the radar signal generation unit 10 to output the transmission wave S1 from the transmission antenna 31, and takes in the signal output S5 of the correlation processing unit 40 as measurement data. At this time, in the exploration wave GS1 at a specific measurement point, a repetition period Ts that randomly changes within a numerical group that changes with a predetermined step size is assigned to each region R1, R2, R3, ... Therefore, the area where noise appears can be limited (see FIG. 8C and the like).

After that, the main control unit 80 performs noise evaluation using the noise evaluation processing unit 50 (step S32). For the noise evaluation, the same method as in the first embodiment can be used, and the noise level is detected for each of the regions A1, A2, A3, ... In the response wave SR.

Next, the main control unit 80 corrects the measurement data based on the noise level obtained for each of the regions A1, A2, A3, ... In step S32 (step S33). Specifically, the regions A1, A2, A3, ... Corresponding to the radio waves whose noise level is below the permissible value or the radio waves having the lowest noise level are selected, and the delay time and the response strength are associated with the signals in the selected region. It is possible to obtain measurement data at a specific measurement point. In this case, the measurement data corresponding to the region where the noise appears is partially removed, but the partially missing measurement data can be used as it is as the exploration information for display. However, the exploration information is not limited to the measurement data in which the area where noise appears is removed, but processing such as interpolation is performed from the measurement data in the corresponding area of the measurement points before and after, and coloring indicating the presence of noise is displayed. It can be assumed that various processes such as the above are performed.

The structure, shape, size, and arrangement relationship described in the above embodiments are merely schematically shown to the extent that the present invention can be understood and implemented. Therefore, the present invention is not limited to the described embodiment, and can be changed to various forms as long as it does not deviate from the scope of the technical idea shown in the claims.

For example, in the above embodiment, the step size when changing the repeat period Ts is constant, but it is not necessary to accurately position the step width, and the repeat cycle Ts can be changed with a slightly fluctuating step width.

The radar device 100 can be mounted on a moving body and moved, but the moving body is not limited to a moving body such as an automobile or a train that is moved by a prime mover, and may be manually moved by a user. good.

The radar device 100 of the embodiment can be used not only for ground penetrating radar but also for exploration of various objects including space.

10 ... Radar signal generator, 20a ... Transmitter, 20b ... Receiver, 21 ... Transmission amplifier, 22 ... Reception amplifier, 31 ... Transmit antenna, 32 ... Reception antenna, 40 ... Correlation processing unit, 50 ... Noise evaluation processing Unit, 70 ... Timing control unit, 80 ... Main control unit, 90 ... Display unit, 100 ... Radar device, 101 ... Control unit, A1, A2, A3 ... Region, DP ... Spectral peak, GS ... Exploration wave, GS1, GS2, GS3, ... Exploration wave, NS ... Noise source, NZ ... Noise signal, OB ... Exploration object, P2 ... Reflection waveform, R1, R2, R3, ... Region, S1, SP ... Transmission wave, S2, SR ... Response Wave, S3 ... Reference signal, S5 ... Signal output, S7 ... Trigger signal

Claims (10)

A transmitter that periodically transmits radio waves for exploration,
A receiver that receives radio waves in synchronization with the radio waves for exploration,
It is equipped with a control unit that detects the state of the target based on the received radio wave and changes the repetition cycle of the radio wave transmitted from the transmission unit.
The control unit is a radar device that detects a target state in a state in which the spectral peak of the transmitted radio wave and the noise signal from the noise source deviate from each other. The control unit causes the receiving unit to receive radio waves while changing the repetition period within a predetermined range, and when the noise level of the received radio waves is equal to or less than a predetermined allowable value, the noise level is equal to or less than the predetermined allowable value. The radar device according to claim 1, wherein the transmitting unit performs a radio wave transmission operation and the receiving unit performs an operation synchronized with the transmitting unit at a repetition cycle corresponding to the above. The control unit causes the receiving unit to receive radio waves while changing the repeating cycle within a predetermined range, and causes the transmitting unit to perform a radio wave transmitting operation in a repeating cycle in which the noise level of the received radio waves is the lowest. The radar device according to claim 1, wherein the receiving unit is made to perform an operation synchronized with the transmitting unit. The radar according to claim 1, wherein the control unit causes the transmitting unit to perform a transmission operation while changing the repetition cycle of radio waves within a predetermined range, and causes the receiving unit to perform an operation synchronized with the transmitting unit. Device. The radar device according to claim 4, wherein the control unit extracts information in the depth direction using radio waves having a noise level of less than or equal to a predetermined allowable value or radio waves having the lowest noise level. The radar device according to any one of claims 4 and 5, wherein the control unit changes the repetition period to discrete values having a predetermined step size. The radar device according to any one of claims 4 to 6, wherein the control unit changes the repetition period with a random amount of change. The radar device according to any one of claims 1 to 7, wherein the radio wave transmitted periodically has a pulse-shaped waveform or a chirp-shaped waveform having no carrier wave component. The radar device according to any one of claims 1 to 8, wherein the target state is detected by a sampling method using a reference signal or a correlation method. According to any one of claims 1 to 9, the transmitting unit periodically transmits radio waves for ground penetrating radar, and the receiving unit receives radio waves in synchronization with the radio waves for ground penetrating radar. The radar device described.

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