JP2003329767A - Radar equipment - Google Patents

Abstract

(57) [Summary] The present invention has been made in view of the above circumstances, and can measure the distance or relative speed of each measurement object even when there are two or more measurement objects.
It is an object of the present invention to provide a radar apparatus having a short distance measurement cycle per direction during scanning. SOLUTION: Frequency modulation means 11 for generating a transmission wave
Transmitting and receiving means 15a for transmitting the generated transmission wave and receiving the reflected wave from the object to be measured, scanning means 21 for repeatedly scanning the transmitting and receiving direction of the transmitting and receiving means in a predetermined scanning range, and transmitting and receiving waves. A signal processing means 10 for obtaining a distance or a relative speed to a measurement target based on the frequency modulation means 11,
A first transmission wave that alternately repeats any two of the frequency rising section 31, the frequency falling section 32, and the frequency non-modulation section 33, and a second transmission wave that repeats the remaining one section are generated. And the second transmission wave are switched in synchronization with the scanning cycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device, and more specifically, it detects an object to be measured by transmitting a radio wave and receiving a reflected wave thereof, and a distance to the detected object and a relative velocity. The present invention relates to a radar device for calculating, for example, a vehicle-mounted radar device.

[0002]

2. Description of the Related Art FIG.
It is the figure which showed the mode when performing radar measurement about one measurement target. In the figure, 71 is a radar device, 72 is a scanning range of the radar device, 73 is a measurement target, R is the distance to the measurement target, V is the relative speed with the measurement target, and θ is the direction of the measurement target. The radar device 71 is mounted on a moving body such as a vehicle, transmits and receives radar signals, and analyzes the frequency of the radar signal to measure the distance, relative speed, and direction with other moving bodies. , Measurement target 73
Is a radar device mounted on a vehicle following the vehicle.

The radar device 71 frequency-modulates a transmission wave and transmits the same, and at the same time, an object 7 to be measured of the transmission wave.
The reflected wave in No. 3 is received, and the distance R to the measurement target 73 and the relative speed V are calculated based on the frequencies of the beat signals of the reflected wave and the transmitted wave. In addition, the transmission direction is changed within the scanning range 72 having a predetermined angle to measure the measurement target 7
The direction θ of 3 is calculated. The relative speed V is positive in the direction in which the radar device 71 and the measurement target 73 are separated, and the direction θ is the angle with respect to the traveling direction of the vehicle in which the radar device 71 is installed.

FIG. 16 is a diagram showing an example of transmission / reception waveforms of the radar device 71 of FIG. 15, where the vertical axis represents frequency and the horizontal axis represents time, and the waveforms of the transmitted wave (solid line) and the received wave (broken line). It is shown. The transmission wave is subjected to triangular wave frequency modulation in which an ascending section 81 in which the frequency is linearly increased on the time axis and a descending section 82 in which the frequency is linearly decreased are alternately repeated. Is fm, the center frequency is f0, and the modulation width is Δf. Repeat cycle 1 / fm
The transmission / reception time 86 is the time from the start of transmission of the transmission wave corresponding to 1 to the end of reception of the reflected wave.

Between the transmitted wave and the received wave, there is a measurement target 73.
A deviation Δt in transmission / reception time is generated based on the distance R up to, and a deviation (Doppler shift) fb is generated in the center frequency based on the relative speed V with respect to the measurement target 73. Therefore, by mixing the transmission / reception signals, a beat signal of frequency fu is obtained in the rising section 81 and a beat signal of frequency fd is obtained in the falling section 82.

FIG. 17 is a diagram showing an example of the power spectrum of the beat signal obtained based on the transmitted / received waves of FIG. 16, in which the vertical axis represents the reception intensity and the horizontal axis represents the frequency. The spectral distribution of the beat signal in the section 82 is shown. Fr in the figure is fu and fd
, Fp is the distance from fu and fd to fr, and fu and fd are the following formula (1) using fr and fp.
It is represented by (2).

[Equation 1]

Here, fr is the distance R to the object 73 to be measured.
, Fp is an amount proportional to the relative velocity V of the measuring object 73, and fr and fp are expressed by the following equations (3) and (4) using the light velocity C, the distance R, and the relative velocity V. .

[Equation 2]

From the above equations (1) to (4), the radar device 71
The distance R from the measurement object 73 to the measurement object 73, and the relative velocity V of the radar device 71 and the measurement object 73 are expressed by the following equations using the addition and subtraction processing of fu and fd, respectively.

[Equation 3]

However,

[Equation 4]

As shown in the above equations (7) to (10), if the frequency fu of the beat signal in the rising section 81 and the frequency fd of the beat signal in the falling section 82 are obtained, the distance R to the measuring object 73, The relative speed V with respect to the measurement target 73 can be obtained.

By the way, the above-described radar device can accurately obtain the distance R and the relative velocity V of the measurement target 73 when there is only one measurement target 73.
When there are a plurality of 3s, there is a problem that it is difficult to determine the distance R and the relative speed V to each measurement target.

FIG. 18 is a diagram showing a situation in which radar measurement is performed on two measurement targets using a conventional radar device. In the figure, 71 is a radar device, 72 is a scanning range of the radar device, 7a and 7b are measurement targets, Ra and Rb are distances to the measurement target, and Va and Vb are relative velocities to the respective measurement targets. The radar device 71 includes measurement targets 7a and 7
It is a radar device mounted on a vehicle subsequent to the two vehicles of b.

Similar to FIG. 17, FIG. 19 is a diagram showing an example of the power spectrum of the beat signal obtained when there are two measurement targets. The modulated signal shown in FIG. The case of sending is shown. When there are two measurement targets, at least the frequency components of the beat signals obtained in the rising section 81 and the falling section 82 of the frequency modulation of the triangular wave shown in FIG. That is, the ascending section 8
The frequency components fua and fub of the beat signal obtained by reflecting one transmission wave on the two measurement targets 7a and 7b and the transmission wave on the falling section 82 are obtained by reflecting on the two measurement targets 7a and 7b. Frequency components fda and fdb of the beat signal are generated.

Therefore, when there are two measurement targets, {fua, fda}, {fua, fdb}, {fu
b, fda}, {fub, fdb}, if two correct combinations for the measurement targets 7a, 7b are not selected from the four combinations, the distances Ra, Rb and the relative speeds to the measurement targets 7a, 7b. There is a problem that wrong values are calculated as Va and Vb.

FIG. 20 is a diagram showing another example of transmission / reception waveforms of the conventional radar device 71, in which the vertical axis represents frequency and the horizontal axis represents time, and the transmitted wave (solid line) and the received wave (broken line) are shown. The waveform is shown. This signal waveform is provided in order to solve the above-mentioned problems when there are two or more measurement targets.
It is disclosed in Japanese Laid-Open Patent Publication No. 233.

This transmission wave is frequency-modulated by repeating an ascending section 121 and a descending section 122 whose frequency changes with time and an unmodulated section 123 where the frequency does not change with time, so that the ascending section 121 and the descending section. A correct combination is selected from a plurality of frequency component combinations obtained from the beat signal in 122 on the basis of the frequency components of the beat signal in the non-modulation section 122. Hereinafter, the conventional technique according to Japanese Patent Laid-Open No. 7-20233 will be described in detail.

When there are two measurement objects 7a and 7b, the ascending section 121 and the descending section 122 shown in FIG.
The frequency components of the beat signal obtained by the transmission wave at the frequency components fua and fub based on the rising section 81 and the frequency component f based on the falling section 82 are the same as in FIG.
It consists of da and fdb. And two measurement objects 7a,
The distances Ra and Rb of 7b are {fua, f as described above.
da} {fua, fdb} {fub, fda} {fu
Two correct combinations must be selected from the four combinations of b, fdb}.

The non-modulation section 123 shown in FIG.
The frequency component of the beat signal obtained by the transmission wave at is composed of two frequency components fca and fcb. Of the two measurement targets 7a and 7b, the one with the slowest running speed is
a, the faster traveling speed is 7b, that is, fca <f
Assuming cb, the respective velocities Va and Vb are given by the following equation (1
It is obtained by 1) and (12).

[Equation 5]

Here, the ascending section 121 and the descending section 122
And the frequency component fu obtained in the non-modulation section 123
The relationships of the following equations (13) and (14) are established between a, fub, fda, fdb, fca, and fcb.

[Equation 6]

That is, between the frequency fu of the beat signal obtained in the rising section 121, the frequency fd of the beat signal obtained in the falling section 122, and the frequency fc of the beat signal obtained in the non-modulation section 123, fd- fu = 2 · fc
When these relationships are established, it can be determined that these three frequency components belong to a single measurement target.

Therefore, it is possible to determine the frequency component of the beat signal for the measurement object 7a as {fua, fda} and the frequency component of the beat signal for the measurement object 7b as {fub, fdb}. Even when there are a plurality of measurement targets, there is a high possibility that the correct distance and relative velocity can be obtained, as compared with the radar device that uses the transmitted wave consisting of only the ascending section and the descending section.

By the way, when the transmitted wave and the received wave are detected by a mixer or the like, if the frequency component of only the real part of the beat signal (hereinafter referred to as the in-phase component) is used, the hardware elements constituting the radar can be reduced. Because you can
It is advantageous for downsizing and cost reduction, and is used in various radar devices. However, with such a configuration, the absolute value of the frequency to be measured can be obtained, but the positive and negative signs cannot be obtained. Specifically, since all are folded back into the non-negative frequency range, the equations (1) and (2) are expressed by the following equations (15) and (16).
It is transformed like.

[Equation 7]

Equations (15) and (16) are classified as follows according to the signs of fu and fd, and are expressed as follows.

[Equation 8]

As described above, when the frequency components of only the real part of the beat signal are used, the number of types (choices) of combinations is quadrupled. Therefore, the correct combination can be selected from the combinations of these frequency components. There was the problem of becoming more difficult.

Japanese Unexamined Patent Publication No. 10-132925 discloses a radar signal processing method for solving such a problem. According to this radar signal processing method, as shown in FIG.
As in the case of 0, using a radar device that frequency-modulates the frequency of the transmitted wave into the rising section 121, the non-modulation section 123, and the falling section 122, the distance R of the measurement target R The speed V can be obtained.
The details will be described below.

In the non-modulation section 123, the frequency fc of the beat signal is determined by the relative speed V with respect to the measurement object,
fc is expressed by the following equation (25) using the relative velocity V.

[Equation 9] According to the equations (17) to (24), | fu + fd |, | fu
Either one of -fd | matches twice fp,
Since fp = fc according to the equation (25), it can be determined that the one that matches 2fc is a multiple of fp, and the one that does not match is a multiple of fr.

FIG. 21 is a diagram showing an example of the transmission / reception waveform of the radar device 71 and the beat signal of each of the measurement objects moving away from and approaching, and FIG. 21A shows the case of the measurement objects moving away from each other. , (B) show the case of an approaching measurement object. As can be seen from FIG. 21, in the detection of only the in-phase component,

[Equation 10] Therefore, the sign of the Doppler frequency component fc can be determined by comparing fu and fd.

Further, since the distance R> 0, the frequency component fr due to the distance is given by the following equation (27).

[Equation 11]

As can be understood from the above description, the formula (2
From 5) to (28), the magnitude of fr and fp and the positive / negative relationship are obtained, and equations (7) to (10) and equations (17) to (24) are obtained.
Thus, the distance R and the relative speed V of the measurement object 73 can be obtained.

Steps 2201-2 of FIGS. 22 and 23
Reference numeral 215 is a flowchart showing the conventional radar signal processing method described in the above publication, and shows the radar signal processing method when there are a plurality of measurement targets. According to this flowchart, the distance Rmn and the relative speed Vmn to each measurement object can be obtained even when there are a plurality of measurement objects. Hereinafter, FIG. 22 and FIG.
Each step of will be described in detail.

Step 2201: One or more target candidates are detected from the frequency spectrum of the beat signal in the rising section 121 of the modulation frequency and each frequency is obtained. For example, the reception intensity is compared with a predetermined threshold value to detect peaks of the frequency spectrum that are equal to or higher than the threshold value, and these frequencies fu (i) {i = 1, 2, ..., I} are obtained.

Step 2102: Frequency non-modulation section 1
One or two or more target candidates are detected from the frequency spectrum of the beat signal in 23, and each frequency is calculated. For example, the reception intensity is compared with a predetermined threshold value to detect peaks of the frequency spectrum above the threshold value, and these frequencies fc (k) {k = 1, 2, ..., K} are obtained.

Step 2203: One or more target candidates are detected from the frequency spectrum of the beat signal in the falling section 122 of the modulation frequency, and the respective frequencies are obtained. For example, the reception intensity is compared with a predetermined threshold value to detect the peaks of the frequency spectrum above the threshold value, and these frequencies fd (j) {j = 1, 2, ..., J} are obtained.

Step 2204: The frequencies fu (i) {i = 1, 2, ..., I} and fd (j) of the target candidate spectra detected in Step 2201 and Step 2203.
For all combinations of {j = 1, 2, ..., J},
Frequency sum fsum according to the following equations (29) and (30)
(I, j) and frequency difference fdif (i, j) are obtained.

[Equation 12]

Step 2205: Frequency fc (k) of each target candidate detected in step 2202 {k = 1, 2,
,, K} is calculated as fsum obtained in step 2204.
Fc compared with (i, j) and fdif (i, j)
(L) = fsum (m, n) or fc (l) = fd
Select fu (m) and fd (n) as if (m, n) as the correct combination.

Step 2206: fc (l) is fsum
It is determined whether or not it is equal to (m, n). If they are equal, the process proceeds to step 2207, and if they are not equal, step 2211 is performed.
Go to.

Step 2207: fc (l) = fsum
In the case of (m, n), first, the distance frequency fr (m, n) is set to fdif (m, n).

Step 2208: Next, fu (m) and f
The sizes of d (n) are compared, and if fu (m) ≧ fd (n), the process proceeds to step 2209, where fu (m) <fd
If (n), the process proceeds to step 2210.

Step 2209: Velocity frequency fp (m,
n) is set to fsum (m, n) and the process proceeds to step 2215.

Step 2210: Velocity frequency fp (m,
n) is set to −fsum (m, n) and the process proceeds to step 2215.

Step 2211: On the other hand, fc (l) ≠ f
In the case of sum (m, n), first, the range frequency fr (m,
Let n) be fsum (m, n).

Step 2212: Next, fu (m) and f
The sizes of d (n) are compared. If fu (m) ≧ fd (n), the process proceeds to step 2213, where fu (m) <fd
If (n), the process proceeds to step 2214.

Step 2213: Velocity frequency fp (m,
n) is set to fdif (m, n) and the process proceeds to step 2215.

Step 2214: Velocity frequency fp (m,
n) is set to −fdif (m, n), and the process proceeds to step 2215.

Step 2215: Obtained fr (m,
Based on n) and fp (m, n), the relative distance Rmn and the relative speed Vmn are calculated from the equations (3) and (4).

[0046]

As described above, in the case of a radar apparatus that uses a frequency-modulated wave composed of a frequency rising section 81 and a frequency falling section 82 as a transmission wave, when there are a plurality of measurement objects, each measurement object is measured. There is a problem that it is difficult to determine the distance and the relative speed with.

In order to solve such a problem, the above-mentioned publications (JP-A-7-20233, JP-A-10-132925).
In the conventional radar device described in No. 1), as a transmission wave, a frequency rising section 121, a falling section 122, and a non-modulation section 1
By using the frequency-modulated wave composed of 23, the distance R and the relative velocity V with respect to each of the plurality of measurement objects are obtained.

However, in the case of such a radar device, in addition to the rising section 121 and the descending section 122, it is necessary to perform the frequency spectrum analysis for the non-modulation section 123, so that only the calculation time for the non-modulation section is required.
There has been a problem that the distance measurement cycle (the cycle of acquiring the distance and the relative speed) per direction during scanning becomes long.

Further, if the scanning directions at the time of transmitting the respective transmission waves of the rising section 121, the falling section 122 and the non-modulation section 123 are different, it becomes difficult to match the measurement targets.
Stop scanning so that the transmission and reception directions are the same from the time the transmission wave is transmitted until the reception wave is received, or
Alternatively, it is desirable to reduce the scanning speed. However, there is a problem that a scanning mechanism system that can stop scanning is generally complicated and expensive. Further, when the scanning speed is reduced, there is a problem that the scanning range becomes narrow or the scanning cycle for scanning a predetermined scanning range becomes long.

Further, in order to suppress the distance measuring cycle 1 / fm to a predetermined time or less, the transmission / reception time 126 in FIG.
6 is equal to the transmission / reception time 86, the transmission wave shown in FIG.
The time of the ascending section 121 and the descending section 122 is the ascending section 8
1, it becomes shorter than the time of the descending section 82, and FFT (Fi
There is a problem that the number of samplings in the rst Fourier transfer) processing unit is reduced and the measurement accuracy of distance and relative speed is deteriorated.

The present invention has been made in view of the above circumstances, and it is possible to measure the distance or relative velocity of each measurement object even when there are two or more measurement objects, and to measure the distance or relative velocity of each measurement object in one direction. It is an object of the present invention to provide a radar device having a short distance measurement period.

Further, according to the present invention, when there are two or more measurement objects without lowering the measurement accuracy, increasing the distance measurement cycle, complicating the mechanical system, increasing the cost, or narrowing the scanning range. However, it is an object of the present invention to provide a radar device capable of measuring the distance or relative velocity of each measurement target.

[0053]

According to a first aspect of the present invention, there is provided a radar device according to the present invention, wherein a frequency increasing section in which a frequency increases on a time axis, a frequency decreasing section in which a frequency decreases on a time axis, and a frequency indicates a time axis. A frequency modulation unit that generates a transmission wave composed of a frequency-unmodulated section that is constant above, a transmission / reception unit that transmits the generated transmission wave and that receives a reflected wave from the measurement target, and a transmission / reception direction of the transmission / reception unit The radar device is provided with a scanning unit that repeatedly scans in the scanning range, and a signal processing unit that obtains a distance or a relative velocity with respect to the measurement target based on the transmitted wave and the received wave. , A first transmission wave that alternately repeats any two sections of the frequency falling section and the frequency non-modulation section, and a second transmission wave that repeats the remaining one section Configured so that the first transmission wave and the second transmission wave is switched in synchronization with the scanning cycle.

A radar device according to a second aspect of the present invention is configured such that the first transmission wave and the second transmission wave are alternately transmitted in each scanning cycle.

In the radar apparatus according to the third aspect of the present invention, the first transmission wave includes a frequency rising section and a frequency falling section, and the second transmission wave includes a frequency non-modulation section.

In the radar apparatus according to the present invention as set forth in claim 4, the frequency modulation means has a first transmission wave in which any two sections of a frequency rising section, a frequency falling section and a frequency non-modulation section are alternately repeated. A second transmission wave that alternately repeats the remaining one section and any one section that constitutes the first transmission wave is generated, and the first transmission wave and the second transmission wave are synchronized with the scanning cycle. It is configured to be switched.

A radar device according to the present invention as defined in claim 5 is configured such that the first transmission wave and the second transmission wave are alternately transmitted in each scanning cycle.

According to a sixth aspect of the radar apparatus of the present invention, the first transmission wave is composed of a frequency rising section and a frequency falling section, and the second transmission wave is composed of a frequency rising section and a frequency unmodulated section. Become.

According to a seventh aspect of the radar device of the present invention, the first transmission wave is composed of a frequency rising section and a frequency falling section, and the second transmission wave is composed of a frequency falling section and a frequency unmodulated section. Become.

In the radar apparatus according to the present invention as defined in claim 8, the first transmission wave comprises a frequency rising section and a frequency non-modulation section, and the second transmission wave comprises a frequency falling section and a frequency non-modulation section. Consists of.

According to a ninth aspect of the present invention, there is provided a radar device in which a frequency modulation means for generating a transmission wave, a transmission / reception means for transmitting the generated transmission wave and a reflected wave by a measuring object, and a transmission / reception means. Scanning means for repeatedly scanning the transmitting / receiving direction in a predetermined scanning range, beat signal generating means for generating a beat signal by a transmitted wave and a received wave, and a signal for obtaining a distance or relative speed to a measurement object based on the beat signal A radar device comprising a processing means, wherein the frequency modulation means has a frequency increasing section in which the frequency increases on the time axis, a frequency decreasing section in which the frequency decreases on the time axis, and the frequency becomes constant on the time axis. Generate a first transmission wave that repeats 2 or less sections of the frequency non-modulation section and a second transmission wave that repeats 2 or less sections including all the remaining sections Configured so that the first transmission wave and the second transmission wave is switched in synchronization with the scanning cycle.

A radar device according to a tenth aspect of the present invention is configured such that the first transmission wave and the second transmission wave are alternately transmitted in each scanning cycle.

In the radar apparatus according to the present invention as set forth in claim 11, the signal processing means has beats in a frequency rising section, a frequency falling section and a frequency unmodulated section for each of a plurality of scanning directions included in the scanning range. It is configured to obtain the distance or relative velocity with respect to the measurement target from the frequency.

According to the twelfth aspect of the present invention, in the radar device according to the present invention, the signal processing means determines the absolute value of the frequency sum and the absolute value of the frequency difference for each combination of the beat frequency in the frequency rising section and the beat frequency in the frequency falling section. Based on the sum of the frequencies, the step of obtaining, the step of selecting the combination of the beat frequency in the frequency rising section and the beat frequency in the frequency falling section in which the absolute value of the frequency sum or frequency difference is equal to the beat frequency in the frequency unmodulated section, It is configured to execute a process including a step of obtaining a distance to the measurement target and a step of obtaining a relative speed with the measurement target based on the frequency difference for each scanning direction.

In the radar device according to a thirteenth aspect of the present invention, the beat signal generating means obtains the frequency component of the real part of the beat signal obtained from the transmitted wave and the received wave, and the signal processing means obtains it. Based on the beat frequency, the distance or the relative speed with respect to the measurement target is obtained.

In the radar apparatus according to the 14th aspect of the present invention, the signal processing means determines the absolute value of the frequency sum and the frequency difference for each combination of the beat frequency in the frequency rising section and the beat frequency in the frequency falling section. The step of obtaining, the step of selecting the combination of the beat frequency of the frequency rising section and the beat frequency of the frequency falling section where the absolute value of the frequency sum or frequency difference is equal to the beat frequency of the frequency unmodulated section, and the frequency sum or frequency difference Of the absolute value of the difference between the beat frequency of the frequency non-modulation section and the distance to the measurement target, and the absolute value of the frequency sum or frequency difference that is equal to the beat frequency of the frequency non-modulation section On the basis of the above, it is configured to execute the process including the step of obtaining the relative speed with respect to the measurement target for each scanning direction. It is.

[0067]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. FIG. 1 is a block diagram showing a configuration example of a radar device according to a first embodiment of the present invention. In the figure, 1 is a radar device, 10 is a signal processing device, 11 is an oscillator, 12 is a power divider, 13 is a transmission amplifier, 14 is a circulator, 15a is a horn antenna, 15b is an antenna reflector, 16 is a receiving amplifier, 1
Reference numeral 7 is a mixer, 18 is a filter, 19 is an amplifier, 20 is an A / D converter, and 21 is an antenna scanning motor.

The horn antenna 15a is an antenna for both transmission and reception, and the antenna reflecting mirror 15b reflects the transmission and reception waves of the horn antenna 15a, and the horn antenna 15a.
Has directivity. That is, the horn antenna 15
A and the antenna reflecting mirror 15b constitute a directional antenna. The antenna scanning motor 21 is a driving device for rotationally driving the antenna reflecting mirror 15b, and based on a control signal output from the signal processing device 10 in accordance with the scanning direction, the antenna angle (for example, the antenna in a horizontal plane). The direction is controlled, and the transmission / reception direction is controlled.

The oscillator 11 generates a frequency-modulated transmission signal based on the control signal from the signal processing device 10. The transmission signal generated by the oscillator 11 is branched into two in the power divider 12, one of which is input to the mixer 17 and the other is amplified by the transmission amplifier 13 and then radiated from the horn 15 a via the circulator 14. To be done.

The radio wave output from the horn antenna 15a is reflected by the antenna reflecting mirror 15b and radiated into space in a predetermined transmission direction. The radio wave emitted to the space is diffusely reflected by the measurement target (not shown), and a part of the reflected wave is
The light is reflected again by the antenna reflecting mirror 15b, is incident on the horn antenna 15a, and is received.

This reception signal is amplified by the reception amplifier 16 via the circulator 14, and then mixed with the above transmission signal by the mixer 17. The reception signal has a delay time Δt with respect to the transmission signal, and the horn antenna 1
When the object to be measured has a relative velocity with respect to the radar device, it is input to the horn antenna 15a with a Doppler shift fb for the transmission signal.

Therefore, in the mixer 17, a beat frequency signal corresponding to the delay time Δt and the Doppler shift fb is generated. In addition, in the first and second embodiments, the frequency of the beat signal obtained by the mixer 17 is provided with a symbol.

The generated beat frequency signal passes through the filter 18, is amplified by the amplifier 19, and is input to the A / D converter 20 and further to the signal processing device 10. In the signal processing device 10, the frequency spectrum analysis of the beat frequency signal is performed, and the distance to the measurement target and the relative speed are obtained based on the analysis result.

In this radar apparatus, the antenna scanning motor 21 drives the antenna reflecting mirror 15b to repeatedly scan the transmitting / receiving direction of the radar apparatus within a predetermined scanning range. The scanning range further includes a plurality of scanning directions, and the radar device 1 repeats the above operation in each scanning direction.

FIG. 2 is a diagram showing an example of transmission / reception waveforms of the radar device 1 of FIG. 1, where the vertical axis represents frequency and the horizontal axis represents time, and the waveforms of the transmitted wave (solid line) and the received wave (broken line). It is shown. 16A, as in FIG. 16, a triangular wave in which an ascending section 31 in which the frequency is linearly increased on the time axis and a descending section 32 in which the frequency is linearly decreased on the time axis are alternately repeated at a repetition cycle of 1 / fm. The transmission / reception signal subjected to the frequency modulation is shown. On the other hand, (b) shows a frequency-unmodulated signal whose frequency does not change with time. That is, it is composed of only the frequency non-modulation section 33. The oscillator 11 generates two types of transmission signals, that is, either one of (a) and (b) of FIG. 6 based on the instruction of the signal processing device 10.

FIG. 3 is a diagram showing an example of the scanning direction of the radar device 1 of FIG. The antenna reflecting mirror 15b driven by the antenna scanning motor 21 changes the horn antenna 15a in each of the scanning directions 40 to 44 to scan the scanning range 4
0 to 44 are scanned at a predetermined scanning cycle.

FIG. 4 is a diagram showing an example of switching timing of the transmission wave generated by the oscillator 11. The oscillator 11 that generates two types of transmission waves shown in FIG. 2 generates the same transmission wave within the same scanning cycle and switches the transmission waves in synchronization with the scanning cycle. FIG. 4 shows an example in which the transmission wave is switched for each scanning cycle. That is,
In the 2n-th (n = 0, 1, 2, ...) Scan cycle, frequency modulation including the rising section 31 and the falling section 32 shown in FIG. 2A is performed for each of the scanning directions 40 to 44 in FIG. The signal is transmitted. Further, in the (2n + 1) th scanning cycle, as shown in FIG.
The frequency unmodulated signal shown in is transmitted.

Steps 501 to 506 of FIG. 5 are flowcharts showing an example of the radar signal processing method according to the first embodiment of the present invention, and FIGS.
5 is a flowchart showing details of steps 504 to 506. According to these flowcharts, the distance Rmn and the relative speed Vmn to each measurement object can be obtained even if there are a plurality of measurement objects without lengthening the measurement cycle per direction. Hereinafter, each step of the flowchart of FIG. 5 will be described in detail.

Step 501: The signal processing apparatus 10 uses a counter Sc for recognizing what number of scanning cycle it is.
AnCnt is provided, the counter ScanCnt indicating the scanning cycle is incremented, and the processing for each scanning cycle is started.

Step 502: The signal processing device 10 is provided with a counter DCnt for recognizing the number of the scanning direction 40 to 44 in the same scanning cycle.
Reset DCnt. Therefore, its value is zero,
First, the following processing is performed for the first scanning direction 40.

Step 503: When the counter ScanCnt is an even number, the process proceeds to a step 504, and when the counter ScanCnt is an odd number, a step 5 is performed.
Go to 05. That is, step 504 and step 50
5 is alternately executed every scanning cycle.

Step 504: The peak frequency fu of the beat signal in the rising section and the falling section in the falling section are scanned in each scanning direction 40 to 44 while scanning the transmission wave composed of the rising and falling modulation signals shown in FIG. 2A. After the peak frequency fd of the beat signal is obtained, the process proceeds to step 506.

Step 505: While scanning the transmission wave composed of the non-modulated signal shown in FIG.
After the peak frequency fc of the beat signal is obtained for .about.44, the process proceeds to step 506.

Step 506: The signal processing device 10 performs the arithmetic processing on the basis of fu, fd and fc obtained in Step 504 and Step 505, and one or more measurement objects are set in each of the scanning directions 40 to 44. The distance R and the relative speed V of are calculated. Then, the process returns to step 501 again.

Steps 601 to 606 in FIG. 6 are a flow chart showing the details of step 504 (scanning by the rising / falling modulation signal) in FIG. 5, and the rising / falling modulation signal is used to move up in each scanning direction. A processing method for obtaining the peak frequencies fu and fd of the beat signal in each of the section and the falling section is shown. Hereinafter, each step of the flowchart of FIG. 6 will be described in detail.

Step 601: Based on the value of the counter DCnt, the antenna scanning motor 21 causes the antenna reflecting mirror 15b.
Is rotated to change the transmitting / receiving direction by the horn antenna 15a.

Step 602: The oscillator 11 generates a transmission wave composed of the modulation frequency rising section 31 and the frequency falling section 32 shown in FIG. 2A based on the command from the signal processing apparatus 10. Is output from the horn antenna 15a.

Step 603: One or more target candidates are detected from the frequency spectrum of the beat signal in the rising section 31 of the modulation frequency in one scanning direction,
Find each frequency. For example, the reception intensity is compared with a predetermined threshold value, and I peaks (I is 1 or 2 or more) in the frequency spectrum that is equal to or higher than the threshold value are detected, and these frequencies fu (i, DCnt) {i = 1, 2, , 3, ..., I}.

Step 604: For one scanning direction, one or more target candidates are detected from the frequency spectrum of the beat signal in the falling section 32 of the modulation frequency,
Find each frequency. For example, the reception intensity is compared with a predetermined threshold value, and J peaks (J is 1 or 2 or more) of the frequency spectrum above the threshold value are detected, and these frequencies fd (j, DCnt) {j = 1, 2 are obtained. , 3, ..., J}.

Step 605: Counter showing the scanning direction
By incrementing DCnt, the next scanning direction 41, 42,
... are targeted for processing.

Step 606: If the counter DCnt is less than 5, the process returns to step 601, and the same operation (steps 601 to 605) is repeated for the new scanning direction. If the counter DCnt is 5 or more, 40 to 4 in all scanning directions
Since scanning has been completed for No. 4, the process is ended and the process proceeds to step 506 in FIG.

Steps 701 to 705 of FIG. 7 are a flow chart showing the details of step 505 (scanning by an unmodulated signal) of FIG. 5, in which the peak frequency of the beat signal is used for each scanning direction using the unmodulated signal. A processing method for obtaining fc is shown. Hereinafter, each step of the flowchart of FIG. 7 will be described in detail.

Step 701: Based on the value of the counter DCnt, the antenna scanning motor 21 causes the antenna reflecting mirror 15b.
Is rotated to change the transmitting / receiving direction by the horn antenna 15a.

Step 702: The oscillator 11 generates a transmission wave in which the frequency shown in FIG. 2B is unmodulated based on the command from the signal processing device 10, and the transmission wave is output from the horn antenna 15a. It

Step 703: For one scanning direction, one or more target candidates are detected from the frequency spectrum of the beat signal of the non-modulated frequency, and the respective frequencies are obtained. For example, the reception intensity is compared with a predetermined threshold value, and one or more peaks (K is 1 or 2 or more) of the frequency spectrum that is equal to or higher than the threshold value are detected, and these frequencies fc (k, DCnt) { Find k = 1, 2, 3, ..., K}.

Step 704: Counter showing scanning direction
By incrementing DCnt, the next scanning direction 41, 42,
... are targeted for processing.

Step 705: If the counter DCnt is less than 5, the process returns to step 701 and the same operation (steps 701 to 704) is repeated for the new scanning direction. If the counter DCnt is 5 or more, all scanning directions 40 to 44
Since the scanning has been completed for, the process ends and the process proceeds to step 506 in FIG.

Steps 801 to 810 in FIG. 8 are flowcharts showing the details of step 506 (arithmetic processing) in FIG. 5, and are for obtaining the distances and relative velocities to two or more measurement objects for each scanning direction. The processing method is shown. Hereinafter, each step of the flowchart of FIG. 8 will be described in detail.

Step 801: Counter for indicating scanning direction
DCnt is reset so that the value becomes zero, and the following calculation is performed for the first scanning direction 40.

Step 802: The frequencies fu (i, DCnt) {i = 1,2, ..., I} and fd of the target candidate spectra detected in steps 603 and 604 of FIG.
For (j, DCnt) {j = 1, 2, ..., J}, the frequency sum fsum (i,
j) and the frequency difference fdif (i, j) are expressed by the following equation (31),
Calculated by (32).

[Equation 13]

Step 803: Target candidate frequency fc (k, DCnt) detected in step 703 of FIG. 7 {k =
1, 2, ..., K} and fs obtained in step 802
Comparing um (i, j) and fdif (i, j),
Fc (l), fu satisfying the following expression (33) or (34)
One or more combinations of (m) and fd (n) are selected as the correct combination.

[Equation 14]

Step 804: Distance frequency fr (m,
Let n) be the frequency sum fsum (m, n).

Step 805: fu (m) and fd (n)
Are compared, and if fu (m) ≧ fd (n), the process proceeds to step 806, and if fu (m) <fd (n), the process proceeds to step 807.

Step 806: Velocity frequency fp (m,
n) as the frequency difference fdif (m, n), step 8
Go to 08.

Step 807: Velocity frequency fp (m,
n) is set to -fdif (m, n), and the process proceeds to step 808.

Step 808: fr (m, n) and fp obtained in steps 806 and 807.
From (m, n), the distance R is calculated by the following equations (35) and (36).
mn and the relative velocity Vmn are obtained.

[Equation 15]

Step 809: Counter showing scanning direction
By incrementing DCnt, the next scanning direction 41, 42,
... are targeted for processing.

Step 810: If the counter DCnt is less than 5, the process returns to step 802, and the same operation (steps 802 to 809) is repeated for the new scanning direction. If the counter DCnt is 5 or more, all scanning directions 40 to 44
Since the scanning has been completed for, the process ends and the process returns to step 501 in FIG.

In the radar device according to the present embodiment, the transmission wave of FIG. 2 (a) which is composed of the rising section and the falling section of the modulation frequency and has no non-modulation section, and the transmission wave of FIG. The transmission wave of b) is switched and transmitted for each scanning cycle. Then, the frequency components fu and fd of the beat signal based on the transmission wave of FIG. 2A and the frequencies of the beat signal based on the transmission wave of FIG. The component fc is used to calculate the distance and relative velocity of the measurement target.

That is, without using a transmission wave as shown in FIG. 20, which has an unmodulated section along with a rising section and a falling section of the modulation frequency as in the conventional radar apparatus,
Similar to the conventional apparatus, the beat frequency in the rising section, the falling section, and the non-modulation section is used to determine the distance and the relative speed to the measurement target.

As a result, even if there are two or more measurement targets, incorrect combinations of frequency components can be prevented and correct measurement can be performed, and measurement accuracy decreases, the distance measurement cycle increases, and the mechanical system becomes complicated or It does not cause problems such as high price and narrow scanning range. Therefore,
Even when there are two or more measurement targets, the distance and relative speed to each measurement target can be accurately obtained.

In the present embodiment, the case has been described in which the transmission wave signal consisting of the rising section and the falling section and the transmission wave signal consisting of only the non-modulation section are switched and transmitted for each scanning cycle. Is not limited to such a transmitted wave signal. In other words, the same effect can be obtained if two types of transmission wave signals are generated by arbitrarily combining the three sections of the rising section, the falling section, and the non-modulation section, and are switched and transmitted in synchronization with the scanning cycle. The combination of the three sections may be another combination. Specifically, a transmission wave signal including an ascending section and a non-modulation section and a transmission wave signal including only a descending section may be used, or a transmission wave signal including an unmodulation section and a descending section and an ascending section only. May be used.

Embodiment 2. The configuration and operation of this embodiment are basically the same as those of the first embodiment, but the two types of transmission waves generated by the oscillator 11 are different. Further, the processing contents in the signal processing device 10 are different accordingly.

FIG. 9 is a diagram showing another example of transmission / reception waveforms of the radar device 1 of FIG. 1, where the vertical axis represents frequency and the horizontal axis represents time, and the transmitted wave (solid line) and the received wave (broken line). Waveforms are shown. 9A, similarly to FIG. 2A, the frequency of a triangular wave in which a rising section 31 in which the frequency linearly increases on the time axis and a falling section 32 in which the frequency linearly decreases on the time axis are alternately repeated. A modulated transmission / reception signal is shown. On the other hand, FIG. 9B shows a rising section 34 in which the frequency linearly increases on the time axis and a non-modulation section 33 in which the frequency does not change with time. The oscillator 11 has two types of transmission signals based on an instruction from the signal processing device 10,
That is, the transmission signal of either (a) or (b) of FIG. 9 is generated.

FIG. 10 is a diagram showing an example of the switching timing of the transmission wave generated by the oscillator 11. The oscillator 11 that generates two types of transmission waves shown in FIG. 9 generates the same transmission wave within the same scanning cycle and switches the transmission waves in synchronization with the scanning cycle. In FIG. 10, the transmission wave is switched for each scanning cycle. That is, 2n
In the scan cycle of the nth time (n = 0, 1, 2, ...), the frequency modulation signal including the rising section and the falling section shown in FIG. 9A is transmitted in each of the scanning directions 40 to 44. Further, in the (2n + 1) th scanning cycle, each scanning direction 40
9 to 44, the frequency modulation signal including the rising section and the non-modulation section shown in FIG. 9B is transmitted.

Steps 1101 to 1106 of FIG.
FIG. 12 is a flowchart showing an example of a radar signal processing method according to a second embodiment of the present invention, and FIG. 12 is a flowchart showing details of step 1105 (scanning with an unmodulated signal) in FIG. 11. When the flowchart of FIG. 11 is compared with the case of FIG. 5, only step 1105 is different and the other steps 1101 to 1104 and 1106 are the same as the corresponding steps of FIG. Hereinafter, each step of the flowchart of FIG. 11 will be described in detail.

Step 1101: The signal processing device 10
A counter for recognizing the number of scan cycles
A ScanCnt is provided, the counter ScanCnt indicating the scanning cycle is incremented, and processing for each scanning cycle is started.

Step 1102: The signal processing device 10
A counter DCnt for recognizing which scanning direction 40 to 44 in the same scanning cycle is provided, and this counter DCnt is reset. Therefore, the value becomes zero, and the following processing is performed for the first scanning direction 40.

Step 1103: When the counter ScanCnt is even, the procedure proceeds to step 1104, and when it is odd, the procedure proceeds to step 1105. That is, step 1104 and step 1105 are alternately executed for each scanning cycle.

Step 1104: The peak frequency fu of the beat signal in the rising section 31 and the falling section in each of the scanning directions 40 to 44 are scanned while scanning the transmission wave composed of the rising / falling modulation signal shown in FIG. 9A. After the peak frequency fd of the beat signal at 32 is obtained, the process proceeds to step 1106.

Step 1105: The peak frequency fu of the beat signal in the rising section 34 and the unmodulated signal are scanned in the respective scanning directions 40 to 44 while scanning the transmission wave composed of the rising / unmodulated signal shown in FIG. 9B. After the frequency fc of the beat signal in the section 33 is obtained, step 110
Go to 6.

Step 1106: fu, fd and f obtained in steps 1104 and 1105
The signal processing device 10 performs arithmetic processing based on c, and the distance R and the relative speed V with respect to one or more measurement targets are obtained for each of the scanning directions 40 to 44. At this time, the frequency fu in the rising section is calculated as in step 1104.
Of the values obtained in 1 and 1105, the newer value is used. Then, the process returns to step 1101 again.

FIG. 12 is a flow chart showing the details of step 1105 (scanning by the rising / non-modulation signal) of FIG. 11, in which the rising section / non-modulation signal is used for each scanning direction by using the rising / non-modulation signal. The processing method for obtaining the peak frequencies fu and fc of the beat signal in each of the sections 33 is shown. FIG. 7 is a flowchart of FIG.
Compared with the case of, only step 1203 is different,
Other steps 1201, 1202 and 1204-120
6 is the same as the corresponding step in FIG. Below, Figure 1
Each step of the flowchart of 2 will be described in detail.

Step 1201: Based on the value of the counter DCnt, the antenna scanning motor 21 causes the antenna reflecting mirror 15 to move.
b is rotationally driven to change the transmission / reception direction by the horn antenna 15a.

Step 1202: The oscillator 11 generates a transmission wave composed of the modulation frequency rising section 34 and the frequency non-modulation section 33 shown in FIG. 9B based on the command from the signal processing apparatus 10, and transmits this transmission wave. Wave is horn antenna 15a
Is output from.

Step 1203: For one scanning direction, one or more target candidates are detected from the frequency spectrum of the beat signal in the modulation frequency increasing section 34,
Find each frequency. For example, the reception intensity is compared with a predetermined threshold value, and I peaks (I is 1 or 2 or more) in the frequency spectrum that is equal to or higher than the threshold value are detected, and these frequencies fu (i, DCnt) {i = 1, 2, , 3, ..., I}.

At this time, the frequency fu (i, DCnt) {i of the rising section obtained in step 1104 of FIG. 11 is obtained.
= 1,2,3, ..., I}
Is replaced with new data. In exactly the same way, when step 1104 of FIG. 11 is executed, the fu obtained in step 1203 is overwritten and replaced with new data.

Step 1204: For one scanning direction, one or more target candidates are detected from the frequency spectrum of the beat signal in the frequency non-modulation section 33, and each frequency is obtained. For example, the reception intensity is compared with a predetermined threshold, and K peaks (K is 1 or 2 or more) of the frequency spectrum that is equal to or higher than the threshold are detected, and these frequencies fc (k, DCnt) {k = 1, 2 are obtained. , 3, ..., K}.

Step 1205: The counter DCnt indicating the scanning direction is incremented to the next scanning direction 41, 4
2, ... Are processed.

Step 1206: If the counter DCnt is less than 5, the process returns to step 1201 and the same operation (steps 1201 to 1205) is repeated for the new scanning direction. If the counter DCnt is 5 or more, the scanning is completed in all the scanning directions 40 to 44, and therefore the processing is ended and the process proceeds to step 1106 of FIG. 11.

The radar device according to the present embodiment is composed of the rising and falling sections of the modulation frequency as shown in FIG.
The transmission wave of FIG. 9A and the transmission wave of FIG. 9B composed of the rising section and the non-modulation section are switched and transmitted in synchronization with the scanning cycle. Therefore, the frequency component of the beat signal in the rising section can be obtained for each scanning cycle.
That is, the frequency components of the beat signal in the descending section and the non-modulation section obtained temporally before and after in the unit of the scanning cycle,
The distance and relative velocity of the measurement target are calculated using the frequency components of the beat signal in the rising section obtained in all scanning cycles.

Therefore, it is of course possible to obtain the same effect as that of the first embodiment, but further, the first embodiment.
As compared with the case of 1, the effect that the real-time property of detecting the distance and the relative speed of the measurement target can be improved is also obtained.

In the present embodiment, the example in which the modulation frequency increasing section is added in the scanning period by the non-modulation signal has been described, but the modulation frequency decreasing section may be added instead of the frequency increasing section. In this case, since the frequency component of the beat signal in the frequency falling section can be obtained for each scanning cycle, the same effect can be obtained.

Further, one of the two types of transmission waves is configured as a repeating signal in the frequency rising section and the frequency unmodulated section,
The other may be configured as a repeat signal of the frequency falling section and the frequency non-modulation section. In this case, since the frequency component of the beat signal in the non-modulated section can be obtained for each scanning cycle, the same effect can be obtained.

That is, two types of transmission waves are generated by combining any two different sections of the frequency rising section, the falling section, and the non-modulation section, and any of these transmitting waves includes all three sections. Then, for the section included in both of the two types of transmission waves, the frequency component of the beat signal of the section can be obtained for each scanning cycle, and the real-time property can be improved.

Third embodiment. The configuration and operation of this embodiment are basically the same as those of the first embodiment, but are different in that only the in-phase component of the beat signal is used when the transmission wave and the reception wave are detected by the mixer 17. . Further, the processing contents in the signal processing device 10 are different accordingly.

Steps 1301 to 1306 in FIG.
13 is a flowchart showing an example of a radar signal processing method according to a third embodiment of the present invention, and FIG. 14 is a flowchart showing details of step 1306 (arithmetic processing) of FIG. When the flowchart of FIG. 13 is compared with the case of FIG. 5, only step 1306 is different and other steps 1301 to 1305 are the same as the corresponding steps of FIG. Hereinafter, each step of the flowchart of FIG. 13 will be described in detail.

Step 1301: The signal processing device 10
A counter for recognizing the number of scan cycles
A ScanCnt is provided, the counter ScanCnt indicating the scanning cycle is incremented, and processing for each scanning cycle is started.

Step 1302: The signal processing device 10
A counter DCnt for recognizing which scanning direction 40 to 44 in the same scanning cycle is provided, and this counter DCnt is reset. Therefore, the value becomes zero, and the following processing is performed for the first scanning direction 40.

Step 1303: If the counter ScanCnt is even, the procedure goes to step 1304. If the counter ScanCnt is odd, the procedure goes to step 1305. That is, step 1304 and step 1305 are alternately executed for each scanning cycle.

Step 1304: The peak frequency fu of the beat signal in the rising section and the falling section in the falling section are scanned in each scanning direction 40 to 44 while scanning the transmission wave composed of the rising and falling modulation signals shown in FIG. 2A. The peak frequency fd of the beat signal is obtained. At this time, only the absolute values of the frequencies are obtained as the peak frequencies fu and fd. Then, it progresses to step 1306.

Step 1305: While scanning the transmission wave composed of the non-modulated signal shown in FIG.
For 0 to 44, the peak frequency fc of the beat signal is obtained. At this time, only the absolute value of the frequency is obtained as the peak frequency fc. Then, it progresses to step 1306.

Step 1306: fu, fd and f obtained in steps 1304 and 1305
The signal processing device 10 performs arithmetic processing based on c, and the distance R and the relative speed V with respect to one or more measurement targets are obtained for each of the scanning directions 40 to 44. However, unlike the first and second embodiments, the peak frequencies fu, fd, and fc of the beat signal are obtained as absolute values, so the processing method is different. Then step 1 again
Return to 301.

Steps 1401 to 1415 of FIG. 14 are
14 is a flowchart showing the details of step 1306 (arithmetic processing) in FIG. 13, and shows a processing method for obtaining a distance to two or more measurement targets and a relative speed for each scanning direction. Hereinafter, each step of the flowchart of FIG. 14 will be described in detail.

Step 1401: The counter DCnt indicating the scanning direction is reset so that the value becomes zero, and the following calculation is first performed for the first scanning direction 40.

Step 1402: Step 13 of FIG.
Frequency fu of the spectrum of the target candidate detected in 04
(I, DCnt) {i = 1, 2, ..., I} and fd (j, DCn
t) For {j = 1, 2, ..., J}, the frequency sum fsum (i, j) and the frequency difference fdif (i, j) are calculated by the following equations (37), (38) for all combinations of i, j. ).

[Equation 16]

Step 1403: Step 13 in FIG.
Target candidate frequency fc (k, DCnt) detected in 05
Comparing {k = 1, 2, ..., K} with fsum (i, j) and fdif (i, j) obtained in step 1402, fc that satisfies the following equation (39) or (40)
One or more combinations of (l), fu (m), fd (n) are selected as the correct combination.

[Equation 17]

Step 1404: fc (l) is fsum
It is determined whether or not it is equal to (m, n). If they are equal, the process proceeds to step 1405, and if they are not equal, step 1409
Go to.

Step 1405: fc (l) = fsum
In the case of (m, n), first, the distance frequency fr (m, n) is set as the frequency difference fdif (m, n).

Step 1406: Next, fu (m) and f
The sizes of d (n) are compared, and if fu (m) ≧ fd (n), the process proceeds to step 1407, where fu (m) <fd
If (n), the process proceeds to step 1408.

Step 1407: Speed frequency fp (m,
n) is set to fsum (m, n) and the process proceeds to step 1413.

Step 1408: Velocity frequency fp (m,
n) is set to −fsum (m, n) and the process proceeds to step 1413.

Step 1409: On the other hand, fc (l) ≠ f
In the case of sum (m, n), first, the range frequency fr (m,
Let n) be fsum (m, n).

Step 1410: Next, fu (m) and f
The sizes of d (n) are compared, and if fu (m) ≧ fd (n), the process proceeds to step 1411 and fu (m) <fd.
If (n), the process proceeds to step 1412.

Step 1411: Speed frequency fp (m,
n) is set to fdif (m, n) and the process proceeds to step 1413.

Step 1412: Velocity frequency fp (m,
n) is set to −fdif (m, n) and the process proceeds to step 1413.

Step 1413: Steps 1405-1
From fr (m, n) and fp (m, n) obtained in 412, the distance Rmn and the relative speed Vmn are obtained by the following equations (41) and (42).

[Equation 18]

Step 1414: The counter DCnt indicating the scanning direction is incremented to the next scanning direction 41, 4
2, ... Are processed.

Step 1415: If the counter DCnt is less than 5, the process returns to step 1402, and the same operation (steps 1402-1414) is repeated for the new scanning direction. If the counter DCnt is 5 or more, all scanning directions are 4
Since the scanning is completed for 0 to 44, the processing is ended and the process returns to step 1301 in FIG.

In the radar device according to the present embodiment, when the transmitted wave and the received wave are detected by the mixer 17, only the in-phase component of the beat signal is used, but such a radar device also has the same structure as in the first embodiment. The same effect can be obtained. That is, in order to prevent an incorrect combination of frequency components and to perform accurate measurement even when there are two or more measurement targets, the distance measurement cycle is increased, the mechanical system is complicated or expensive, and the scanning range is narrow. It does not cause the problem of instability. Therefore, the distance to the measurement target and the relative speed can be accurately obtained.

In this embodiment, the radar device that uses only the in-phase component of the beat signal when the mixer 17 detects the transmission / reception wave used in the first embodiment, that is, the transmission / reception wave shown in FIG. However, the present invention can be applied to a radar device in which the mixer 17 detects the transmission / reception waves described in the second embodiment, that is, the transmission / reception waves shown in FIG. 9 and other transmission / reception waves. , A similar effect can be obtained.

[0162]

The radar device according to the present invention generates the first transmission wave and the second transmission wave, switches the first transmission wave and the second transmission wave in synchronization with the scanning cycle, and transmits them. There is.
Each of these transmission waves is composed of two or less sections of a frequency rising section, a frequency falling section and a frequency unmodulated section, and each section is included in either the first transmission wave or the second transmission wave. There is.

Therefore, even when there are two or more measurement targets based on the transmitted wave and the received wave in the frequency rising section, the frequency falling section, and the frequency unmodulated section,
Not only can you measure the distance or relative velocity to the measurement target, but you do not need to use a transmission wave consisting of a frequency rising section, a frequency falling section, and a frequency unmodulated section, and the measurement cycle per direction during scanning can be shortened. can do.

Therefore, even if there are two or more measurement objects, the distance or relative speed of each measurement object can be achieved without causing problems such as deterioration of measurement accuracy, complicated or expensive mechanism system, and narrowed scanning range. A highly accurate measurement can be performed on.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a radar device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a transmission / reception waveform of the radar device 1 of FIG.

3 is a diagram showing an example of a scanning direction of the radar device 1 of FIG.

FIG. 4 is a diagram showing an example of switching timing of transmission waves generated by an oscillator 11.

FIG. 5 is a flowchart showing an example of a radar signal processing method according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing details of step 504 (scanning with an ascending / descending modulation signal) in FIG.

7 is a flowchart showing details of step 505 (scanning with an unmodulated signal) in FIG.

FIG. 8 is a flowchart showing details of step 506 (arithmetic processing) in FIG.

9 is a diagram showing another example of transmission / reception waveforms of the radar device 1 of FIG. 1 (Embodiment 2).

FIG. 10 is a diagram showing an example of switching timing of transmission waves generated by the oscillator 11.

FIG. 11 is a flowchart showing an example of a radar signal processing method according to a second embodiment of the present invention.

FIG. 12 is a flowchart showing details of step 1105 (scanning with an unmodulated signal) in FIG.

FIG. 13 is a flowchart showing an example of a radar signal processing method according to a third embodiment of the present invention.

FIG. 14 is a flowchart showing details of step 1306 in FIG.

FIG. 15 is a diagram showing a state in which radar measurement is performed on one measurement target using a conventional radar device.

16 is a diagram showing an example of a transmission / reception waveform of the radar device 71 of FIG.

17 is a diagram showing an example of a power spectrum of a beat signal obtained based on the transmitted / received waves of FIG.

FIG. 18 is a diagram showing a situation in which radar measurement is performed on two measurement targets using a conventional radar device.

FIG. 19 is a diagram showing an example of a power spectrum of a beat signal obtained when there are two measurement targets.

FIG. 20 is a diagram showing another example of a transmission / reception waveform of the conventional radar device 71.

FIG. 21 is a diagram showing an example of a transmitted / received waveform of the radar device 71 and its beat signal for each of measurement objects that are separated or approached.

FIG. 22 is a flowchart showing a conventional radar signal processing method when there are a plurality of measurement targets.

FIG. 23 is a flowchart diagram showing a conventional radar signal processing method, following FIG. 22;

[Explanation of symbols]

1 radar device, 10 signal processing device, 11 oscillator,
12 power divider, 13 transmission amplifier, 14 circulator, 15a horn antenna, 15b antenna reflector, 16 reception amplifier, 17 mixer, 18
Filter, 19 amplifier, 20 A / D converter, 21
Antenna scanning motor, 31 Frequency rise section, 32
Frequency falling section, 33 frequency unmodulated section, 34 frequency unmodulated section, 40 to 44 scanning direction, fu frequency rising section beat frequency, fd frequency falling section beat frequency, fu frequency unmodulated section beat frequency, fm
Repeat frequency, f0 center frequency, Δf modulation width,

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5J070 AB19 AB22 AC02 AC06 AC13                       AE01 AF01 AH23 AH26 AH31                       AH39 AK15 AK22 BA01

Claims (14)

[Claims] 1. A frequency for generating a transmission wave comprising a frequency rising section in which the frequency increases on the time axis, a frequency falling section in which the frequency decreases on the time axis, and a frequency unmodulated section in which the frequency is constant on the time axis. Modulating means, transmitting / receiving means for transmitting the generated transmitted wave and receiving reflected waves by the measurement object, scanning means for repeatedly scanning the transmitting / receiving direction of the transmitting / receiving means within a predetermined scanning range, and transmitting / receiving waves. In a radar device provided with a signal processing means for obtaining a distance or a relative speed to a measurement object based on the frequency modulation means, the frequency modulation means alternately repeats any two sections of a frequency rising section, a frequency falling section and a frequency non-modulation section. A first transmission wave and a second transmission wave that repeats the remaining one section are generated, and the first transmission wave and the second transmission wave are switched in synchronization with the scanning cycle. Radar and wherein the Erareru. 2. The first transmission wave and the second transmission wave are alternately transmitted for each scanning cycle.
The radar device according to 1. 3. The radar according to claim 1, wherein the first transmission wave is composed of a frequency rising section and a frequency falling section, and the second transmission wave is composed of a frequency unmodulated section. apparatus. 4. A frequency for generating a transmission wave comprising a frequency rising section in which the frequency increases on the time axis, a frequency falling section in which the frequency decreases on the time axis, and a frequency non-modulation section in which the frequency is constant on the time axis. Modulating means, transmitting / receiving means for transmitting the generated transmitted wave and receiving reflected waves by the measurement object, scanning means for repeatedly scanning the transmitting / receiving direction of the transmitting / receiving means within a predetermined scanning range, and transmitting / receiving waves. In a radar device provided with a signal processing means for obtaining a distance or a relative speed to a measurement object based on the frequency modulation means, the frequency modulation means alternately repeats any two sections of a frequency rising section, a frequency falling section and a frequency non-modulation section. A first transmission wave and a second transmission wave that alternately repeats the remaining one section and any one section that constitutes the first transmission wave are generated. Radar device transmitted wave and the second transmission wave is characterized in that it is switched in synchronization with the scanning cycle. 5. The first transmission wave and the second transmission wave are alternately transmitted in each scanning cycle.
The radar device according to 1. 6. The method according to claim 4, wherein the first transmission wave is composed of a frequency rising section and a frequency falling section, and the second transmission wave is composed of a frequency rising section and a frequency unmodulated section. The radar device according to 1. 7. The fourth transmission wave comprises a frequency rising section and a frequency falling section, and the second transmission wave comprises a frequency falling section and a frequency non-modulation section. The radar device according to 1. 8. The method according to claim 4, wherein the first transmission wave includes a frequency rising section and a frequency non-modulation section, and the second transmission wave includes a frequency falling section and a frequency non-modulation section. The radar device according to item 5. 9. A frequency modulation means for generating a transmission wave, a transmission / reception means for transmitting the generated transmission wave and receiving a reflected wave by a measurement object, and a transmission / reception direction of the transmission / reception means are repeatedly scanned within a predetermined scanning range. In a radar device provided with a scanning means, a beat signal generating means for generating a beat frequency from a transmitted wave and a received wave, and a signal processing means for obtaining a distance or a relative speed to a measurement object based on the beat frequency, A means repeats two or less sections of a frequency increase section in which the frequency increases on the time axis, a frequency decrease section in which the frequency decreases on the time axis, and a frequency non-modulation section in which the frequency is constant on the time axis. And a second transmission wave that repeats two or less sections including all remaining sections are generated, and the first transmission wave and the second transmission wave have a scanning cycle. Radar apparatus, characterized by being switched synchronously. 10. The radar device according to claim 9, wherein the first transmission wave and the second transmission wave are alternately transmitted in each scanning cycle. 11. The signal processing means, for each of a plurality of scanning directions included in a scanning range, obtains a distance or a relative speed to a measurement target from each beat frequency in a frequency rising section, a frequency falling section, and a frequency unmodulated section. The radar device according to claim 9, wherein the radar device is obtained. 12. The signal processing means obtains an absolute value of a frequency sum and a frequency difference for each combination of a beat frequency in a frequency rising section and a beat frequency in a frequency falling section, and an absolute value of the frequency sum or frequency difference. Selecting a combination of the beat frequency in the frequency rising section and the beat frequency in the frequency falling section where the value is equal to the beat frequency in the frequency unmodulated section; determining the distance to the measurement target based on the sum of frequencies; 12. The radar apparatus according to claim 11, wherein processing including a step of obtaining a relative speed with respect to the measurement target based on the difference is executed for each scanning direction. 13. The beat signal generation means obtains the frequency component of the real part of the beat signal obtained from the transmitted wave and the received wave, and the signal processing means makes the distance to the measurement object based on the obtained beat frequency. Alternatively, the radar device according to claim 9, 10 or 11, wherein a relative velocity is obtained. 14. The signal processing means obtains the absolute value of the frequency sum and the frequency difference for each combination of the beat frequency in the frequency rising section and the beat frequency in the frequency falling section, and the absolute value of the frequency sum or the frequency difference. The step of selecting the combination of the beat frequency in the frequency rising section and the beat frequency in the frequency falling section where the value becomes equal to the beat frequency in the frequency unmodulated section, and the beat in the frequency unmodulated section of the absolute value of the frequency sum or frequency difference. Based on the value different from the frequency, the step of obtaining the distance to the measurement target, and the relative speed to the measurement target based on the absolute value of the frequency sum or frequency difference that is equal to the beat frequency of the frequency unmodulated section 14. The radar device according to claim 13, wherein the processing including the step of obtaining is executed for each scanning direction.