JP2007033156A - Radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a reflected wave from a moving person is hard to be detected because a sharp peak is hardly generated in a frequency spectrum of a Doppler signal therefrom, in a radar device in a dual-frequency CW monopulse system. <P>SOLUTION: Each Doppler signal in L-channel and R-channel is acquired by two reception parts. Distance information 350 of the L-channel and distance information 352 of the R-channel are acquired from each Doppler signal to a dual-frequency transmission wave of each channel. An absolute value 354 of the difference between both of the distance information is determined in each frequency, and a band 358 whose absolute value exceeds a prescribed threshold D<SB>Err</SB>is treated as one including a noise signal and removed, to thereby acquire an effective frequency band including the Doppler signal based on the reflected wave from an object. Similarly, two kinds of information of an angle at which the reflected wave arrives are acquired corresponding to a transmission frequency based on the Doppler signals in both channels, and the effective frequency band is extracted based on correlation thereof. The moving object is detected and its position or the like is measured based on information of the acquired effective frequency band. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radar device that detects a Doppler signal based on a moving object by switching transmission frequencies in a time-division manner and receiving reflected waves at a plurality of receiving units, and more particularly, due to noise appearing in the spectrum of the received signal and the moving object. Discrimination from Doppler signal.

  Conventionally, a radio wave is irradiated and a radio wave reflected by an object is received, and the distance to the object, the azimuth angle where the object exists, There are microwave radar devices that measure relative velocity. This radar apparatus is used in a moving object monitoring system (hereinafter referred to as a sensor).

  As a distance measurement method using radio waves, an FMCW (Frequency-Modulated Continuous Wave) method, a two-frequency CW (Continuous Wave) method, and the like are known. In particular, the two-frequency CW system transmits a transmission wave having a slightly different frequency alternately by time division. This method extracts the Doppler signal included in the received signal that received the reflected wave from the moving object for each transmission frequency, and measures the distance based on the phase difference of the Doppler signal. The distance to the moving object in the monitoring area can be measured with high accuracy up to a short distance.

  On the other hand, as an angle measurement method using radio waves, there are an antenna switching method, a phased array method, a monopulse method, and the like. In particular, the monopulse method is a method in which the arrival direction of a reflected wave is obtained using the phase difference between signals received by two antennas, and it is possible to obtain a high angular resolution with fewer antennas than the other methods described above. .

  Patent Documents 1 and 2 below describe an on-vehicle radar device (hereinafter referred to as a two-frequency CW monopulse method) that uses a two-frequency CW method for distance measurement and a monopulse method for angle measurement as a collision prevention device for automobiles. Yes.

  A radar using radio waves is very promising as an intrusion detection sensor outdoors because it is not easily affected by weather such as wind and rain, and the position of an object within a monitoring range can be specified.

In general, in the two-frequency CW monopulse system, the received Doppler signal is frequency-analyzed to determine the presence of an object from the peak of the power spectrum, and the distance and angle are calculated from the phase information at the Doppler frequency corresponding to the peak position.
Japanese Patent Laid-Open No. 2003-232853 JP 2002-71793 A

  However, in the case of an intrusion detection sensor, the detection target is a human body or the like, the reception intensity is weaker than that of a vehicle or the like, and it is difficult to obtain a clear peak of the power spectrum. FIG. 8 is a schematic diagram illustrating an example of a power spectrum including a reflected wave from a human body. As shown in the figure, it is difficult to distinguish between the component 2 on the spectrum due to the presence of the moving object and the component due to noise appearing in other frequency ranges, and there is a problem that the detection accuracy of the object is lowered.

  The two-frequency CW monopulse system can obtain two sets of distance and angle measurement values due to its configuration. Patent Document 2 shows that the error can be reduced by averaging the results of each set. In other words, the average of the two sets enables measurement that compensates for the accuracy of Doppler signal peak detection. However, when a peak cannot be detected in the first place, an object cannot be detected with high accuracy only by such a simple averaging method.

  Here, the Doppler signal generated when the human body moves includes not only the moving speed of the whole human body but also the moving speed components of each part in the whole human body. Therefore, in the spectrum of the Doppler signal, the frequency component due to the human body spreads around the moving speed component of the entire human body, which contributes to hindering the formation of sharp peaks in the spectrum, making it more difficult to detect peaks. It is a factor.

  The present invention has been made to solve the above problems, and in a two-frequency CW monopulse sensor, even when a Doppler signal caused by a moving object does not form a sharp peak, the Doppler signal is detected. It is an object of the present invention to provide a radar device that can be used to improve the measurement accuracy of the position of a moving object.

  A radar apparatus according to the present invention includes a plurality of reception units, and transmits two types of transmission waves having different transmission frequencies from a transmission unit in a time-division manner, and receives the reflected waves for the transmission waves by the reception units. Detecting a Doppler signal based on a moving object, means for performing frequency analysis on each of the received signals obtained by the receiving units with respect to the two types of transmission waves, and for each receiving unit, Distance information generating means for generating distance information including propagation distances of the reflected wave obtained for each frequency component based on the result of the frequency analysis corresponding to each transmitted wave, and generated corresponding to the plurality of receiving units. Based on the plurality of distance information, a frequency band of interest corresponding to a frequency range including the Doppler signal of the moving object is extracted from the frequency spectrum of the received signal. And interest band extracting means that those having.

  Another radar apparatus according to the present invention includes a plurality of receiving units, and transmits two types of transmission waves having different transmission frequencies from the transmission unit in a time-division manner, and each of the receiving units generates a reflected wave for each of the transmission waves. For receiving and detecting a Doppler signal based on a moving object, means for performing frequency analysis on each of the received signals obtained by the receiving units for the two types of transmitted waves, and for each type of transmitted wave Angle information generating means for generating angle information including arrival angles of the reflected waves obtained for each frequency component based on the result of the frequency analysis corresponding to each receiving unit, and corresponding to the type of the transmitted wave Based on the two generated angle information, a frequency band of interest corresponding to a frequency range including the Doppler signal of the moving object is extracted from the frequency spectrum of the received signal. And interest band extracting means that those having.

  Still another radar apparatus according to another aspect of the invention includes a plurality of reception units, and two types of transmission waves having different transmission frequencies from each other are transmitted in a time-sharing manner, and each of the reception units reflects a reflected wave with respect to each transmission wave. For detecting a Doppler signal based on a moving object, for each of the receiving units, a means for performing frequency analysis on each of the received signals obtained by the receiving units with respect to the two types of transmission waves, and , Distance information generating means for generating distance information including propagation distance of the reflected wave obtained for each frequency component based on the result of the frequency analysis corresponding to each transmission wave, and for each type of the transmission wave, Angle information generating means for generating angle information including arrival angles of the reflected waves obtained for each frequency component based on the result of the frequency analysis corresponding to each receiving unit, and the plurality of receiving units The Doppler signal of the moving object is included in the frequency spectrum of the received signal based on the plurality of distance information generated correspondingly and the two pieces of angle information generated corresponding to the type of the transmission wave. Interest band extracting means for extracting a frequency band of interest corresponding to the frequency range.

  In another radar apparatus according to the present invention, the band-of-interest extraction unit extracts the frequency band of interest based on a correlation between the plurality of distance information at each frequency component.

  In another radar apparatus according to the present invention, the band-of-interest extraction unit extracts the frequency band of interest based on a correlation between the plurality of pieces of angle information at each frequency component.

  In still another radar apparatus according to the present invention, the band-of-interest extraction unit further extracts the frequency band of interest in consideration of the intensity of the frequency spectrum of the received signal at each frequency component.

  The radar apparatus according to another aspect of the present invention obtains a common attribute band in which a fluctuation range of each of the distance information and the angle information within the frequency band of interest is a predetermined frequency range or less, and the common attribute band is obtained. Labeling means for labeling as corresponding to a single moving object.

  Still another radar apparatus according to the present invention is a frequency range in which variation ranges of the distance information, the angle information, and the intensity of the frequency spectrum of the received signal in the frequency band of interest are equal to or less than a predetermined allowable value. Labeling means is provided for obtaining a common attribute band and labeling the common attribute band as corresponding to a single moving object.

  According to the present invention, the propagation distance of the reflected wave corresponding to each frequency component of the received signal is calculated on the basis of the received signal corresponding to each of the two types of transmitted waves at each receiving unit. A plurality of distance information, which is a propagation distance obtained as a function of frequency, is obtained in correspondence with the number of reception units. Further, the arrival angle of the reflected wave corresponding to each frequency component of the received signal is calculated based on the received signal obtained by each of the plurality of receiving units. Two pieces of angle information, which are arrival angles obtained as a function of frequency, are obtained corresponding to the type of frequency of the transmission wave.

  The distance information and the angle information are formally calculated even if the frequency component of the received signal is not actually based on reflection from an object but is due to noise. However, in the frequency range resulting from noise in the distance information and the angle information, the variation of the calculated value becomes large. In addition, among the distance information obtained in accordance with the number of receiving units, there is no relation in principle in the frequency range caused by noise between the calculated values of the propagation distance with the same frequency component. Similarly, even among a plurality of pieces of angle information obtained in accordance with the type of transmission frequency, the calculated values of the arrival angles at the same frequency component have no relation in principle in the frequency range caused by noise.

  On the other hand, if the frequency component of the received signal is based on reflection from an object, the calculated distance and angle values will be the same or similar, even if the transmission frequency and receiver are changed. Can be expected. Here, when the object has a spread in the velocity distribution like a human body, it is difficult to form a peak on the frequency spectrum. However, in this case, in the frequency range corresponding to the velocity distribution of the object among the distance information and angle information, the calculated values of the distance and angle are almost constant values based on the actual distance and angle with the object. You can expect to be.

  Therefore, in the distance information and the angle information, there is a difference in the distribution form of the calculated values between the frequency range caused by noise and the frequency range caused by the reflected wave from the actual object. According to the present invention, a combination of a plurality of distance information, a combination of a plurality of angle information, or a combination of both of these information allows a moving object based on a difference in distribution form of calculated values in distance information and angle information. Thus, the frequency range of the Doppler signal can be accurately distinguished from the frequency range of noise. In addition, since the intensity of the reflected wave of the same object in the frequency spectrum of the received signal can be expected to be almost constant, combining the intensity with distance information and angle information further improves discrimination accuracy. It becomes possible to make it.

  According to the present invention, since the Doppler signal from the moving object can be extracted with high accuracy, the position of the moving object can be detected with high accuracy.

  Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating a schematic configuration of an intrusion detection device according to an embodiment. This apparatus includes a two-frequency CW monopulse radar device as a sensor, and detects a moving object such as a person appearing in a monitoring area. The transmitting unit 10, two receiving units 20, 22, and A / D (Analog to Digital) conversion unit 30, signal processing unit 40, storage unit 50, and output unit 60.

The transmission unit 10 includes a voltage-controlled oscillator 100, a switching signal generator 102, and a transmission antenna 104. The voltage controlled oscillator 100 is configured to be capable of generating microwave band transmission signals W ₁ and W ₂ having two different frequencies f ₁ and f _2, and switching of the W ₁ and W ₂ is controlled by the switching signal generator 102. Is done.

The switching signal generator 102 generates a switching timing signal for switching the generation of W ₁ and W ₂ in the voltage controlled oscillator 100 by time division. The switching frequency is basically set to at least twice the Doppler frequency that can be generated by the movement of an object to be detected by the apparatus.

  The transmission antenna 104 transmits a transmission signal output from the voltage controlled oscillator 100 to the air.

    The receiving unit 20 includes a receiving antenna 120, a mixer 122, and a switch 124. Similarly, the receiving unit 22 includes a receiving antenna 121, a mixer 123, and a switch 125.

  Receiving antennas 120 and 121 receive the reflected wave with respect to the transmitted wave transmitted from transmitting section 10 and transmit the received signal to mixers 122 and 123, respectively. The receiving antennas 120 and 121 are composed of two antennas having the same directivity characteristic so as to perform monopulse angle measurement, and are arranged at a predetermined interval. Based on the direction facing the monitoring area from the sensor, the right antenna is an antenna R and its signal system is an R channel, the left antenna is an antenna L and its signal system is an L channel.

  Here, the interval between the antenna R and the antenna L is set shorter than the wavelength of the transmission wave from the principle of monopulse angle measurement. For example, when the frequency of the transmission wave is 24 GHz band and the receiving antenna interval is set to the half wavelength, the specific interval is about 6 mm. The principle of monopulse angle measurement will be described later. In principle, due to the difference in position between the two receiving antennas, a difference occurs in the distance to the object measured by each of the antennas R and L. However, the difference is extremely small compared to the distance (for example, 1 m or 10 m) to the object targeted by the apparatus, and the measurement distances by both antennas R and L can be considered to be substantially the same. Furthermore, the directivity characteristics of the two receiving antennas are the same, and the spaces that are received by the antennas R and L substantially match. That is, since the antennas R and L receive reflected waves from the same space, the Doppler spectra based on moving objects detected by the received signals of the R and L channels are basically the same.

  The mixers 122 and 123 respectively mix the reception signals from the reception antennas 120 and 121 and the transmission signal from the voltage controlled oscillator 100 to generate a Doppler signal.

The switchers 124 and 125 respectively distribute the Doppler signals output from the mixers 122 and 123 in conjunction with the switch timing signal output from the switch signal generator 102. These switcher 124 and 125, the Doppler signal generated by the mixer 122 and 123 is separated into the Doppler signal corresponding to the Doppler signal and the transmission signal _{W 2} corresponding to the transmission signal _{W 1.}

  The A / D conversion unit 30 performs appropriate band limitation on the Doppler signals obtained from the switches 124 and 125 and converts the Doppler signals into digital data that can be handled by the signal processing unit 40. Here, the appropriate band limitation is to limit the band only to the Nyquist frequency, that is, a frequency equal to or less than ½ of the sampling frequency for digital conversion.

  The signal processing unit 40 performs processing for specifying the position of the object in the monitoring area based on the waveform data input from the A / D conversion unit 30, and determines whether there is an intruder in the monitoring area, The result is transmitted to the output unit 60. The signal processing unit 40 includes an FFT (Fast Fourier Transform) calculating unit 140, a distance calculating unit 142, an angle calculating unit 144, a noise band removing unit 146, an object position specifying unit 148, and a determining unit 150.

The FFT calculation unit 140 extracts data for a predetermined time width from the waveform data sequentially input from the A / D conversion unit 30, performs frequency analysis, and obtains intensity and phase. Here, the phase obtained from the Doppler signal corresponding to the R channel transmission signal W ₁ is the phase information φ _R1 (f), and the phase obtained from the Doppler signal corresponding to the transmission signal W ₂ is the phase information φ _R2 (f). To do. Similarly, the phases obtained from the Doppler signals corresponding to the transmission signals W ₁ and W ₂ related to the L channel are set as phase information φ _L1 (f) and φ _L2 (f). Further, the intensity information obtained from the R channel Doppler signals corresponding to the transmission signals W ₁ and W ₂ is P _R1 (f), PR ₂ (f), and the intensity information obtained from the L channel Doppler signals is P _L1 (f ), P _L2 (f).

The distance calculation unit 142 performs processing described later based on the phase information obtained by the FFT calculation unit 140, and generates distance information regarding the distance between the object and the sensor. The distance calculation unit 142 generates R channel distance information D _R (f) from the R channel phase information φ _R1 (f), φ _R2 (f), and similarly, the L channel phase information φ _L1 (f), L channel distance information D _L (f) is generated from φ _L2 (f).

The angle calculation unit 144 performs processing to be described later based on the phase information obtained by the FFT calculation unit 140, and generates angle information related to the azimuth angle of the object with respect to the sensor. Angle calculation unit 144, the transmission signal W ₁ of the Doppler signal for the phase information φ _{R1 (f),} φ _L1 generates angle information θ _{1 (f)} from _(f), similarly Doppler signal to the transmission signal W ₂ phase The angle information θ ₂ (f) is generated from the information φ _R2 (f) and φ _L2 (f).

The noise band removal unit 146 includes distance information D _R (f), D _L (f) regarding the R channel and the L channel generated by the distance calculation unit 142 and the transmission signal W ₁ , generated by the angle calculation unit 144, respectively. Based on the angle information θ ₁ (f) and θ ₂ (f) relating to each of W _2, processing described later using the correlation between them is performed, and the frequency spectrum of the Doppler signal obtained by the mixers 122 and 123 is obtained. Of these, a band including a noise signal is excluded, and an effective frequency band (interest frequency band) including a signal capable of specifying the position of an object is extracted. The term “noise” as used herein means an unnecessary signal generated due to the presence of an object other than the presence of an object, and includes various types of noise such as background noise and spike noise generated in equipment. On the other hand, the effective frequency band includes a Doppler signal based on a reflected wave from an object.

  The object position specifying unit 148 performs a labeling process to be described later based on the distance information and the angle information of the effective frequency band obtained by the noise band removing unit 146. When there are a plurality of objects in the monitoring area, the portion corresponding to each object in the effective frequency band is discriminated and separated, each position, velocity, and reflection cross-sectional area are specified, and output to the determination unit as object information.

  The determination unit 150 performs intrusion determination from the object information generated by the object position specifying unit 148. If the intrusion is determined, the output unit 60 is notified.

  The storage unit 50 stores information such as distance difference and angle difference thresholds used by the noise band removing unit 146, a monitoring region used by the determination unit 150, and a reflection intensity threshold to be processed.

  Upon receiving the notification that there is an intruder from the determination unit 150, the output unit 60 issues an alarm by light or sound, or transmits an abnormality detection signal to a monitoring center or the like via a communication line connected to the apparatus. .

Next, the operation of this apparatus will be described. FIG. 2 is a schematic flowchart showing the overall operation of the apparatus. Waveform data is acquired in synchronization with the operation in which the transmission unit 10 alternately transmits the transmission signals W ₁ and W ₂ in a time division manner (S200). The reflected wave for each transmission signal is received by the reception antennas 120 and 121, and the reception signals for the R channel and the L channel are obtained. Received signals of each channel are mixed transmission signals at mixers 122 and 123, after being converted to a Doppler signal is separated into a signal for the signal and the transmission signal W ₂ to the transmission signal W _1. The Doppler signal separated for each transmission signal of each channel is sampled at a predetermined frequency by the A / D conversion unit 30 and converted into digital data to generate waveform data. The generated waveform data is stored in a memory in the A / D converter 30.

  The signal processing unit 40 performs processing for specifying the distance and azimuth angle of the object from the waveform data obtained from the received signal and determining the two-dimensional position of the object in the monitoring area (S205). Details of the processing will be described later.

  Based on the information obtained by the two-dimensional position specifying process S205, it is determined whether or not an object of the detection target size exists in the monitoring area (S210). That is, it is determined whether the size of the object obtained in step S205 satisfies a predetermined condition, for example, a size that is equal to or larger than a size that can be regarded as a human body, and the detected position is within a preset monitoring area. Is done. Here, when a plurality of objects are detected, each determination is made individually.

  When an object of the detection target size is detected in the monitoring area (S210), the time existing in the monitoring area of the object is measured. Specifically, the signal processing unit 40 assigns a timer to each detected object and measures the time. If an object is detected in step S210, it is determined whether the object is an object whose timer has already been activated (S215). If the timer is not activated, a timer is assigned to the object and activated, and time measurement is started (S220).

  This timer is used to prevent an object that has entered the monitoring area for a moment, such as a branch of a tree outside the monitoring area, from being detected as an intruder. Is for. For this purpose, when it is determined in the determination process S210 that the object is outside the monitoring area, the timer assigned to the object is cleared (S225). On the other hand, if any one of the activated timers exceeds the specified value, the object corresponding to the timer is handled as an intruder (S230), and the output unit 60 is instructed to generate an alarm. (S235). The output unit 60 issues an alarm by light or sound, or transmits an abnormality detection signal to a monitoring center or the like via a communication line. If none of the running timers exceeds the specified value in process S230, the monitoring process of processes S200 to S230 is repeated.

Subsequently, the two-dimensional position specifying process S205 in the signal processing unit 40 will be described. FIG. 3 is a schematic flowchart of the process. First, the waveform data generated by the A / D conversion unit 30 is subjected to frequency analysis by the FFT calculation unit 140 and phase information φ _R1 (f), φ _R2 (f), φ _L1 (f), φ of the Doppler signal. _L2 (f) and intensity information _PR1 (f), _PR2 (f), _PL1 (f), and _PL2 (f) are calculated (S250). Here, each phase information, the intensity information is a function of the frequency f, this frequency corresponds to the Doppler frequency f _d. The obtained phase information is used for the distance calculation S255 in the distance calculation unit 142 and the angle calculation S260 in the angle calculation unit 144.

The distance calculation unit 142 calculates a distance value for each frequency based on the phase information of each of the R channel and the L channel. Thus, distance information D _R (f) for the _R channel and distance information D _L (f) for the L channel are obtained. Here, the distance is calculated based on the principle of the two-frequency CW method, and specifically, is calculated for each frequency component by the following equation.

In this equation, D represents the distance [m], c represents the speed of light [m / s], and Δφ represents the phase difference [rad] given from the phase information for W ₁ and the phase information for W ₂ .

  The Doppler frequency corresponds to the moving speed of the target object, and the correspondence is given by the following equation.

In this formula, v is the relative velocity between the sensor [m / s], c is the speed of light [m / s], f is transmitted the frequency [Hz], and a is _{f d} is the Doppler frequency [Hz].

The angle calculation unit 144 calculates the azimuth angle at which the reflected wave arrives for each frequency based on the phase information for each transmission signal. Thus, the angle information theta ₁ at the transmission frequency f _{1 (f),} the angle information θ _{2 (f)} are obtained at the transmission frequency f _2. Here, the angle is calculated based on the principle of monopulse radar. Specifically, the angle is calculated for each frequency component by the following equation.

  In this equation, θ is the azimuth angle [deg] around the sensor, c is the speed of light [m / s], Δφ is the phase difference [rad] given by the R channel phase information and the L channel phase information, d Represents an antenna arrangement interval [m], and f represents a transmission frequency [Hz].

である。この場合、上記θを与える（３）式は、位相差Δφだけをパラメータとした次式に単純化できる。 Here, if the interval d between the receiving antennas 120 and 121 is set to half of the transmission wavelength λ,

It is. In this case, the equation (3) that gives θ can be simplified to the following equation using only the phase difference Δφ as a parameter.

The distance information D _R (f), D _L (f) and the angle information θ ₁ (f), θ ₂ (f) obtained in the processes S255 and S260 are the frequencies of the Doppler signals extracted by the receiving units 20 and 22. Of the spectrum, the effective frequency band including the component based on the reflected wave from the object and the band consisting of the noise component are used for the process of discriminating (S265). The noise band removing unit 146 obtains an effective frequency band, and removes unnecessary noise parts from the distance information D _R (f), D _L (f) and the angle information θ ₁ (f), θ ₂ (f). , Distance information D _Ave (f) obtained by averaging distance information D _R (f) and D _L (f) in the effective frequency band, and angle information obtained by averaging angle information θ ₁ (f) and θ ₂ (f). θ _Ave (f) is generated and output.

The processing in the noise band removing unit 146 will be described in more detail. By distance angle conversion, distance information is obtained as a pair of D _R (f) and D _L (f), and angle information is obtained as a pair of θ ₁ (f) and θ ₂ (f).

In the configuration of this apparatus, since the positions of the two receiving antennas 120 and 121 are close, the distance from each antenna to the object can be regarded as the same. That is, when the reflected wave from the object is received by the sensor, basically, the distance corresponding to each frequency of the reflected wave is the distance information D _R (f) and the distance information D _L (f). It becomes the same value.

Further, since the angle information is also generated based on signals received by the same pair of antennas, basically, the angle corresponding to each frequency of the reflected wave is the angle information θ ₁ (f) and the angle information. θ ₂ (f) is the same value.

Here, (2) the frequency f _d of the Doppler signal as will be appreciated from the equation, corresponding to the object velocity v. Therefore, when a moving object exists in the monitoring space, a signal component due to the reflected wave is detected in a frequency band corresponding to the moving speed. On the other hand, a noise component is detected in a frequency band other than the frequency band of the signal component due to the reflected wave.

Graphs 350 and 352 in FIG. 4 are schematic diagrams illustrating an example of distance information for each Doppler frequency component, where the horizontal axis represents the Doppler frequency and the vertical axis represents the distance. The graph 350 represents D _L (f), and the graph 352 represents D _R (f) generated in a pair with the D _L (f). Distributions 300 and 302 of distance calculation values for frequency components having a reflected wave from a moving object have substantially the same value in each of the distance information D _R (f) and D _L (f), while the frequency has no reflected wave. The range of the calculated distance distribution values 304 and 306 for the components in the distance axis direction is wide. Further, between the distance information D _R (f) and D _L (f), the distance value of the distribution value 300 and the distance value of the distribution 302 with respect to the frequency component having the reflected wave from the moving object. And their values are basically equal, while there is basically no correlation between the distribution 304 and the distribution 306 of distances for frequency components without reflected waves. Here, although the example of distance information was shown by FIG. 4, it is the same also about angle information.

As described above, the distance information D _R (f), the distance information D _L (f), the angle information θ ₁ (f), and the angle information θ ₂ (f) are each included in the frequency component having the reflected wave from the moving object. There is a strong correlation. On the contrary, there is no correlation in the frequency component without the reflected wave from the moving object. Using this property, the noise band removing unit 146 uses the distance information D _R (f), D _L (f) and the angle information θ ₁ (f), θ ₂ (f) to generate frequency components without reflected waves. The remaining frequency is removed and extracted as a frequency component (effective frequency band) due to reflection from the object. The specific process is shown below.

The noise band removing unit 146 calculates a difference for each frequency component with respect to the distance information D _R (f), D _L (f) obtained from the distance calculating unit 142, calculates an absolute value of the difference, and the absolute value is a predetermined value. A frequency larger than the threshold value D _Err is extracted and set as a distance noise frequency. FIG. 4 is a schematic explanatory diagram of this process. A graph 354 represents the absolute value of the difference between D _R (f) and D _L (f) shown in the graphs 350 and 352. A frequency at which the absolute value of the difference is larger than the threshold value D _Err indicated by a dotted line in the graph 354 is set as the distance noise frequency. A range 358 indicated by diagonal lines in the graph 356 is a band corresponding to the distance noise frequency.

The distance noise identification value D _N (f) is defined as follows as a state value indicating whether or not the frequency belongs to the band of the distance noise frequency.

The same processing as the distance information is performed on the angle information. That is, the angle information θ ₁ (f), θ ₂ (f) obtained from the angle calculation unit 144 is obtained for each frequency component, and the absolute value of the difference is calculated. The absolute value is calculated from a predetermined threshold value θ _Err . The larger frequency is the angular noise frequency. Then, the angle noise identification value θ _N (f) is defined as follows as a state value indicating whether the frequency belongs to the band of the angle noise frequency.

Here, the threshold value D _Err related to the distance error and the threshold value θ _Err related to the angle error are stored in the storage unit 50 in advance. These threshold values can be determined from, for example, the degree of variation in the calculated values of the distance and angle in the presence or absence of the reflected wave obtained experimentally.

Next, the noise band removing unit 146 assumes that the frequency included in either the distance noise frequency or the angle noise frequency is not a frequency component due to reflection from the object, and is used for subsequent position detection. And the remaining frequency components are extracted as effective frequency bands. That is, D _N (f) · θ _N (f) is calculated, and when the value is 0, the noise region is set, and when the value is 1, the effective frequency band is set.

  The effective frequency band described here means a frequency component obtained by excluding the noise frequency component from the distance information and the angle information, and it should be noted that a plurality of continuous components are not combined into one.

Next, D _R (f) and D _L (f) are averaged for each effective frequency band of the distance information D _R (f) and D _L (f) to obtain average distance information D _Ave (f). Similarly, the angle information θ _Ave (f) is obtained for the angle.

The configuration described above is an example in which the distance error threshold value D _Err and the angle error threshold value θ _Err are constant. In this regard, in the case of the same object, the angle when viewed from the sensor becomes smaller as the object becomes farther. Therefore, the angle error threshold value may be decreased as the distance increases. In this case, for example, the average distance information D _Ave (f) of the effective frequency band is first obtained from the distance error information | D _R (f) −D _L (f) | and the distance error threshold D _Err , and this average distance is obtained. The procedure is to change the angle error threshold θ _Err according to the information D _Ave (f) and extract the effective frequency band of the angle information from the angle error information | θ ₁ (f) −θ ₂ (f) | Can do.

For example, when the object width is 50 cm, if the distance from the sensor is 1 m, it is measured with a spread of 28 degrees, if the distance is 5 m, it is 6 degrees, and if it is 10 m, it is 3 degrees. An error threshold value θ _Err can be set.

  The effective frequency band extraction method is not limited to the above. For example, a configuration in which the effective frequency band is extracted using only one of the correlation between the distance information and the correlation between the angle information is also possible.

Further, regarding the intensity information P _R1 (f), P _R2 (f), P _L1 (f), and P _L2 (f) obtained by the FFT calculation unit 140, the reflection from the object is similar to the distance information and the angle information. In the frequency band based on, the intensity variation is small, the noise part is large, and the intensity information for each channel and each frequency has a strong correlation in the frequency band based on reflection from the object, and in the noise part Correlation weakens. Therefore, it is possible to discriminate between the effective frequency band and the noise portion by using the correlation of the intensity information. At that time, the effective frequency band can be extracted with high accuracy by combining the discrimination based on the intensity information with the discrimination based on the distance information and the angle information.

  The intensity information obtained by the FFT calculation unit 140 may be subjected to threshold processing to remove low power noise, and the above processing may be performed. Further, the effective frequency band may be extracted by storing the intensity of the noise component when there is no moving object in the monitoring space in the storage unit 50 and using the difference from the component when the object exists. .

As described above, when information regarding the effective frequency band is obtained, the object position specifying unit 148 starts processing using the information. First, the object position specifying unit 148 uses the same distance, the same angle, and the same movement from the average distance information D _Ave (f) and the average angle information θ _Ave (f) of the effective frequency band extracted by the noise band removing unit 146. A signal having a velocity (continuous frequency components) is determined as a reflection signal from the same object, and unique labeling (hereinafter, labeling) is performed (S270).

  When an object having various velocities is moving, such as when a person moves, the same distance and angle in a wide frequency band of distance information and angle information as in the example of the distance in the distributions 300 and 302 in FIG. It becomes.

  Utilizing this property, when the distance and angle values of adjacent frequencies are close, they are grouped into one group (hereinafter referred to as grouping), and each is labeled.

  The grouping conditions include, for example, a condition that the distance and angle are within a movement range in which a person can move within a certain time obtained by the A / D conversion unit 30, a condition of a Doppler frequency range generated by a person, or simply a distance. May be within a range of ± 0.5 m and an angle within ± 1 degree. For example, this condition is set according to the characteristics of the object to be detected. Also, this condition can be stored in advance in the storage unit 50 and read and used when necessary.

  When there are multiple objects with close speeds for all Doppler frequencies in the effective frequency band, the Doppler frequencies are continuous on the frequency axis, and as a result of noise removal processing, multiple objects are in the continuous effective frequency band. May exist. FIG. 5 is a schematic diagram showing such an example. ID1, ID2, and ID3 in the figure are labeled frequency bands. Among these, ID1 and ID2 are examples in which a plurality of objects exist within a continuous effective band. Since two objects corresponding to ID1 and ID2 exist at the same distance, the moving speed is close, and the Doppler frequency is continuous, the distance information is extracted as one object. However, since the angle information is different, the result is labeled as two objects. Incidentally, the case of ID1 and ID2 can be separated into two objects by matching the distance and angle as the grouping conditions to the size of the object to be detected as in the effective band extraction process.

Next, the object position specifying unit 148 calculates a representative value of distance, angle, speed, and intensity for each label separated by labeling, and maps it to a two-dimensional plane (S275). The intensity averages the intensity information _PR1 (f), _PR2 (f), _PL1 (f), and _PL2 (f) for each frequency, and extracts only the part corresponding to the effective frequency band of distance information and angle information. The average intensity information P _Ave (f) is used. Here, the distance, the angle, and the speed are the same, but when the intensity is remarkably different, it may be excluded from the average target or may be labeled as another object.

The calculation of the representative value is calculated by the average value of the values included in each label or the weighted average by the average intensity information P _Ave (f), and is used as object information for each label.

  FIG. 6 is a schematic diagram illustrating a setting example of a coordinate system of a two-dimensional plane to be mapped. The two-dimensional plane to be mapped is, for example, as shown in FIG. 6A, a coordinate system in which the front direction of the sensor 400 is the y axis and the right direction is the x axis, or as shown in FIG. When the sensor 400 is installed on the pole 402 and monitored obliquely below, the coordinate system on the ground can be set such that the depth direction on the ground plane is the y-axis and the lateral direction is the x-axis.

  FIG. 7 is a schematic diagram showing an example of mapping. FIG. 7 shows the positions of the objects labeled ID1, ID2, and ID3 in FIG.

  Subsequently, the object position specifying unit 148 performs a relabeling process S280. An object having various velocity components such as a human body has a wide frequency band of the Doppler frequency, but it is not necessarily distributed uniformly, and the Doppler component may be discontinuous in places on the frequency axis. In this case, in the labeling process S270, the label is divided despite the same object. In order to bring this together, re-labeling is performed.

When the position, velocity, and intensity of each label on the two-dimensional position obtained by mapping are close, the labels are combined to form one label. Here, when there is a discontinuous point, whether or not to use one label is determined after mapping on a two-dimensional plane. However, distance information and angle information are processed in step S270. You may perform about each of.

  Similar to the determination in the labeling process S 270, the determination of the coupling can be performed in consideration of the distance range in which the person can move during the predetermined time obtained by the A / D conversion unit 30, the Doppler frequency range generated by the person, and the like.

  With this re-labeling, the object information of each label is updated. The distance information and the angle information mapped on the two-dimensional plane have a spread according to the size of the object. As described above, after labeling as one object on the two-dimensional plane, the labeled range can be used for determining the size of the object.

  This is because the distance and angle from each part differ depending on the size of the object, but the frequency band containing the information generated due to the existence of the object is considered as the effective frequency band from the frequency spectrum. By extracting, the size information of the object can be obtained.

  According to the radar apparatus according to the present invention described above, it is possible to measure a good position even when the peak of the Doppler spectrum due to a moving object is not clear. For this reason, it is possible to detect a wide range of objects such as weakly reflected objects and object positions having various velocities, and the intrusion detection device using the radar device can reduce misreports and false alarms and improve reliability. Figured.

It is a block diagram which shows the schematic structure of the intrusion detection apparatus which concerns on embodiment. It is a schematic flowchart which shows the whole operation | movement of the intrusion detection apparatus which concerns on embodiment. It is a general | schematic flowchart of the two-dimensional position specific process in a signal processing part. It is typical explanatory drawing of the extraction process of the effective frequency band by a noise band removal part. It is a schematic diagram explaining an example of labeling. It is a schematic diagram which shows the example of a setting of the coordinate system of the two-dimensional plane to map. It is a schematic diagram which shows the example of mapping. It is a schematic diagram which shows an example of the power spectrum containing the reflected wave from a human body.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Transmission part, 20, 22 Reception part, 30 A / D conversion part, 40 Signal processing part, 50 Storage part, 60 Output part, 100 Voltage control oscillator, 102 Switching signal generator, 104 Transmission antenna, 120, 121 Reception antenna 122, 123 mixer, 124, 125 switcher, 140 FFT calculation unit, 142 distance calculation unit, 144 angle calculation unit, 146 noise band removal unit, 148 object position specifying unit, 150 determination unit.

Claims (8)

A Doppler signal based on a moving object, comprising a plurality of receiving units, time-division-transmitting two types of transmission waves having different transmission frequencies from the transmission unit, and receiving the reflected waves for the respective transmission waves by the respective reception units. In a radar device for detecting
Means for performing frequency analysis on each of the received signals obtained by the receiving units with respect to the two types of transmission waves;
Distance information generating means for generating distance information including propagation distances of the reflected waves obtained for each frequency component based on the result of the frequency analysis corresponding to each of the transmission waves, for each of the receiving units;
Interest of extracting a frequency band of interest corresponding to a frequency range including the Doppler signal of the moving object from the frequency spectrum of the received signal based on the plurality of distance information generated corresponding to the plurality of receiving units. Band extraction means;
A radar apparatus comprising: A Doppler signal based on a moving object, comprising a plurality of receiving units, time-division-transmitting two types of transmission waves having different transmission frequencies from the transmission unit, and receiving the reflected waves for the respective transmission waves by the respective reception units. In a radar device for detecting
Means for performing frequency analysis on each of the received signals obtained by the receiving units with respect to the two types of transmission waves;
Angle information generating means for generating angle information including arrival angles of the reflected waves obtained for each frequency component based on the result of the frequency analysis corresponding to each receiving unit for each type of the transmission wave;
Interest of extracting a frequency band of interest corresponding to a frequency range including the Doppler signal of the moving object from the frequency spectrum of the received signal based on the two pieces of angle information generated corresponding to the type of the transmitted wave Band extraction means;
A radar apparatus comprising: A Doppler signal based on a moving object, comprising a plurality of receiving units, time-division-transmitting two types of transmission waves having different transmission frequencies from the transmission unit, and receiving the reflected waves for the respective transmission waves by the respective reception units. In a radar device for detecting
Means for performing frequency analysis on each of the received signals obtained by the receiving units with respect to the two types of transmission waves;
Distance information generating means for generating distance information including propagation distances of the reflected waves obtained for each frequency component based on the result of the frequency analysis corresponding to each transmission wave for each of the receiving units;
Angle information generating means for generating angle information including arrival angles of the reflected waves obtained for each frequency component based on the result of the frequency analysis corresponding to each receiving unit for each type of the transmission wave;
The moving object in the frequency spectrum of the received signal based on the plurality of distance information generated corresponding to the plurality of receiving units and the two pieces of angle information generated corresponding to the type of the transmission wave A band of interest extracting means for extracting a frequency band of interest corresponding to a frequency range including the Doppler signal;
A radar apparatus comprising: The radar apparatus according to claim 1 or 3,
The radar apparatus according to claim 1, wherein the band-of-interest extraction unit extracts the frequency band of interest based on a correlation between the plurality of distance information at each frequency component. The radar apparatus according to claim 2 or 3,
The radar apparatus according to claim 1, wherein the band-of-interest extraction unit extracts the frequency band of interest based on a correlation between the plurality of pieces of angle information at each frequency component. The radar apparatus according to any one of claims 1 to 5,
The said interested band extraction means is a radar apparatus characterized by further extracting the said interested frequency band in consideration of the intensity | strength of the said frequency spectrum of the said received signal with each said frequency component. The radar apparatus according to claim 3, wherein
Assuming that a common attribute band is obtained in a frequency range in which the fluctuation range of each of the distance information and the angle information within the frequency band of interest is a predetermined allowable value or less, and the common attribute band corresponds to a single moving object. A radar apparatus comprising labeling means for performing labeling. The radar apparatus according to claim 3, wherein
A common attribute band in which the fluctuation range of each of the distance information, the angle information, and the intensity of the frequency spectrum of the received signal within the frequency band of interest is within a predetermined allowable value range is obtained, and the common attribute band is determined. A radar apparatus comprising labeling means for performing labeling as corresponding to a single moving object.

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