JP4950537B2 - Moving object detection device - Google Patents

Description

The present invention relates to an apparatus for identifying a moving object by extracting a Doppler frequency based on the moving object by performing frequency analysis of the Doppler signal. In particular, to drop a human body moving and identifiable moving object detection device, such as rain drops.

  In recent years, the speed and movement of moving objects are analyzed by frequency analysis of Doppler signals obtained by transmitting radio waves such as microwaves and millimeter waves to a monitoring space and receiving reflected waves from objects existing in the monitoring space. Sensors that measure the distance to an object are known. Of these, a two-frequency CW method is known as a method for measuring the distance to a moving object with high accuracy by transmitting and receiving two types of radio waves having slightly different frequencies.

  The two-frequency CW method is a method for obtaining a distance from a phase difference between received waves corresponding to two types of transmitted transmission frequencies. Usually, since the phase of the received wave cannot be directly measured, a method of generating a Doppler signal by mixing the transmitted wave and the received wave and obtaining the distance to the moving object from the phase difference is employed.

The following Patent Documents 1 and 2 describe an in-vehicle radar device that uses a two-frequency CW system as an automobile collision prevention device.
Japanese Patent Laid-Open No. 2003-232853 JP 2002-71793 A

  However, when the two-frequency CW method is used for a sensor for detecting human intrusion into the monitoring space, a Doppler signal generated by a water droplet falling directly under the sensor may be a problem. The intensity of the Doppler signal is proportional to the reflection cross section of the moving object and is inversely proportional to the fourth power of the distance between the sensor and the moving object. There is no problem because the intensity is very small, but when a raindrop falls at a very close distance from the sensor, the intensity of the Doppler signal becomes very strong, and in some cases it is some distance away from the sensor in the monitoring space There has been a problem that the Doppler signal caused by a person moving in position cannot be measured correctly.

  In addition, if the speed of a plurality of moving objects is originally different, it is possible to classify a plurality of objects by the Doppler frequency obtained by frequency analysis of the Doppler signal, but the Doppler signal resulting from the raindrop falling phenomenon as described above is Because it is an impulse-like signal with a short duration, the Doppler frequency component obtained by frequency analysis of the Doppler signal has a strong intensity and a wide spread on the frequency axis. However, there was a problem that it was buried in the Doppler frequency component due to the fall of raindrops.

In order to solve such a problem, the present invention provides a transmission unit for time-division transmission of a plurality of transmission waves having different frequencies to a monitoring space, a reception unit for receiving a reflected wave with respect to the transmission wave, and for each transmission wave A Doppler signal extracting means for extracting a Doppler signal from the transmission wave and the reflected wave, a difference signal generating means for generating a plurality of difference signals of the plurality of Doppler signals corresponding to the transmission waves, and the plurality of difference signals. A phase difference calculating means for calculating a phase difference between them, a Doppler frequency calculating means for calculating a Doppler frequency of the Doppler signal from the phase difference, and an amplitude of the difference signal at the Doppler frequency and the phase difference at the Doppler frequency. and intensity distribution calculating means for calculating the intensity distribution of the reflection from a moving object from distance based, based on the phase difference in the Doppler frequency A velocity distribution calculating means which calculates the velocity distribution of the moving object from the velocity at Ku distance and the Doppler frequency, determine the mass regarded as the same moving object from said intensity distribution, the same movement with reference to the velocity distribution in the distance between the masses There is provided a moving object detection apparatus comprising: a determination unit that determines presence / absence of a moving object to be detected based on a degree of likelihood of being detected for each object.

  Further, the phase difference calculating means calculates at least a plurality of sets of phase differences, and the Doppler frequency calculating means compares the plurality of sets of phase differences and extracts a substantially coincident frequency band as a Doppler frequency. Is preferred.

Further, a transmission frequency interval ratio calculating means for calculating a ratio of frequency intervals between the plurality of transmission waves based on a ratio of the plurality of sets of phase differences, and a ratio of frequency intervals calculated by the transmission frequency interval ratio calculating means A correction instruction means for comparing the preset frequency interval ratios and instructing the transmission means to correct the frequency of the transmission wave so as to maintain the preset frequency interval ratio when a variation is detected without matching. Are preferably provided.

  By using the difference signal between the received Doppler signals and performing signal processing that suppresses the amplitude as the distance between the sensor and the moving object gets closer, noise drops such as when a raindrop falls at a position closer to the sensor. It is possible to realize a moving object detection sensor that can eliminate the influence and can measure a wide monitoring area with high accuracy.

  Hereinafter, a moving object detection device according to an embodiment of the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings. In the present embodiment, an example will be described in which the moving object detection device is used for a use of a moving object detection sensor that detects human intrusion into a monitoring space. Further, an example will be described in which a signal to be transmitted / received is a microwave, and microwaves of three different frequencies are transmitted / received in a time division manner.

<Embodiment 1>
FIGS. 1 and 2 are schematic block configuration diagrams of the moving object detection apparatus according to the first embodiment. FIG. 1 shows a transmitter and a receiver in detail, and FIG. 2 shows a processor in detail. ing.

The transmitter 100 includes a staircase wave generator 110 that generates a stepped voltage waveform, a voltage-controlled oscillator 120 that generates a microwave, a backflow of the microwave, and distributes the microwave to the transmission antenna 140 and the mixer 220. The directional coupler 130 and the transmission antenna 140 that radiates microwaves to the monitoring space are configured to transmit continuous microwaves having _three different frequencies f ₁ , f ₂ , and f ₃ to the monitoring space in a time division manner. .

In the present apparatus that uses the three-frequency CW method, the voltage value of the staircase wave defines the frequency of the microwave. The voltage controlled oscillator 120 generates a microwave having a frequency based on the voltage value of the staircase wave. In other words, the staircase wave generator 110 generates a voltage waveform as shown in FIG. 3 in which three types of voltage values appear periodically, whereby the voltage controlled oscillator 120 has the frequencies f ₁ , f ₂ , and f ₃ . Microwaves are generated sequentially. In the present embodiment, f ₁ is 24.15000 GHz, f ₂ is 24.15125 GHz, and f ₃ is 24.15375 GHz.

The generation period of the staircase wave defines the switching frequency of the microwave frequency. That is, in the voltage controlled oscillator 120, the frequency of the microwave is switched in the order of f ₁ → f ₂ → f ₃ → f ₁ →... In synchronization with the staircase wave. The staircase wave is also input to the switch 230 of the receiving unit 200 and is also used for synchronizing the sample hold 240, 242, and 244. The generation period of the staircase wave is usually set to about several tens of kHz to several hundreds of kHz. In the present embodiment, the generation period is 80 kHz. As a result, the switching period is defined as 4.17 μsec.

  The microwave transmitted from the transmission unit 100 is reflected by an object existing in the monitoring space, and is received by the reception unit 200 as a reflected wave. When a moving object exists in the monitoring space, the reflected wave includes a Doppler component due to the moving object.

The receiving unit 200 receives the reflected wave, and mixes the reflected wave and the microwave from the directional coupler 130 to extract only the Doppler component included in the reflected wave, and outputs the mixer 220 as a Doppler signal. , in synchronism with the generation period of the staircase from staircase generator 110 separates the Doppler signal into a by microwave and the frequency f ₃ by by microwave frequency f ₁ and the microwave frequency f ₂ Switcher 230, sample hold 240, 242 and 244 (abbreviated as S / H in FIG. 1) for interpolating each Doppler signal discontinuous by switcher 230, and difference signal calculation unit 250 for calculating the difference between Doppler signals. 255, amplifiers 260 and 265 for amplifying each Doppler difference signal, anti-area for suppressing aliasing distortion of each Doppler difference signal Filter 270, 275, and the A / D converter 280, 285.

  The anti-alias filters 270 and 275 are analog filters having a relatively steep band rejection characteristic. The A / D converters 280 and 285 employ a sampling rate of 11.025 kHz. The Nyquist frequency at this time corresponds to 123 km / h when converted to the speed of the moving object, and is sufficiently higher than the frequency corresponding to the moving speed of the person to be analyzed by the intrusion detection.

  That is, the receiving unit 200 receives a reflected wave, extracts Doppler components of three frequencies included in the reflected wave, selects two different sets of Doppler components, and calculates a difference signal that is a difference between the selected Doppler components. The calculated difference signal is converted into a digital signal and output to the processing unit 300.

Hereinafter, the Doppler signal by the microwave of the frequency f _{1 is called} a first Doppler signal, the Doppler signal by the microwave of the frequency f _{2 is called} a second Doppler signal, and the Doppler signal by the microwave of the frequency f ₃ is called a third Doppler signal.

  A signal obtained by calculating a difference between the first Doppler signal and the second Doppler signal on the time axis is referred to as a first Doppler difference signal, and similarly, a signal obtained by calculating a difference between the second Doppler signal and the third Doppler signal. This is referred to as a second Doppler difference signal.

  Here, when obtaining the difference signal, the processing unit 300 may store the information regardless of which Doppler signal is subtracted from the other. A signal obtained by calculating a difference between the first Doppler signal and the third Doppler signal can also be used. Since it is necessary to obtain the phase difference between the Doppler difference signals based on the principle of the two-frequency CW method, it is necessary to obtain at least two Doppler difference signals from the three Doppler signals.

  Next, processing of the processing unit 300 for the first Doppler difference signal and the second Doppler difference signal will be described with reference to FIG.

  The processing unit 300 includes a processor such as a DSP or a CPU that processes digital signals, a nonvolatile memory such as a FLASH memory that stores programs and parameters, a volatile memory such as a DRAM that temporarily stores processing results, and the like.

The processing unit 300 is configured to store the first Doppler difference signal and the second Doppler difference signal input from the receiving unit 200, buffers 310 and 315 that store the second Doppler difference signal, a frequency to be converted into a complex spectrum by Fast Fourier Transform (FFT) or the like. From the analysis units 330 and 335, the Doppler frequency extraction unit 340 that extracts the Doppler frequency, the Doppler amplitude value, and the Doppler phase difference based on the complex spectrum of the first Doppler difference signal and the second Doppler difference signal, from the moving body detection device to the moving object A distance calculation unit 350 that calculates the distance of the moving object, a velocity distribution calculation unit 370 that calculates the velocity distribution of the moving object, an intensity distribution calculation unit 360 that calculates the intensity distribution of the moving object, and an intrusion determination unit 380 that determines the presence or absence of an intruder. And an output unit 400 that outputs a determination result.
Each of these units includes a program stored in a non-volatile memory as a program and various hardware and firmware.

Hereinafter, each unit included in the processing unit 300 will be described.
The buffer unit 310 stores at least N latest data among the data of the first Doppler difference signal digitized by the A / D converter 280. In the present embodiment, a FIFO (First In First Out) buffer is used, and N is 2048.

  The frequency analysis unit 330 performs window processing using a Hamming window on the data from the buffer unit 310, and performs frequency analysis on the windowed data using FFT to calculate a complex spectrum. Note that a Hanning window or the like may be used as a window function for window processing, and frequency analysis may be performed by a discrete Fourier transform (DFT) or the like.

  The buffer unit 315 and the frequency analysis unit 335 process the second Doppler difference signal. Since the buffer unit 315 is the same as the buffer unit 310 and the frequency analysis unit 335 is the same as the frequency analysis unit 330, description thereof will be omitted.

  The Doppler frequency extraction unit 340 uses a complex spectrum of the first Doppler difference signal input from the frequency analysis unit 330 and a complex spectrum of the second Doppler difference signal input from the frequency analysis unit 335 for the sake of convenience. The complex spectrum of the difference signal is calculated, and the Doppler frequency is calculated using the phase difference between the complex spectra of the three Doppler difference signals.

  Specifically, the Doppler frequency is detected by using the relationship that the ratio of the phase difference components of the complex spectrum of each of the first Doppler difference signal and the second Doppler difference signal substantially coincides with the transmission frequency interval ratio. The two phase differences between the three Doppler signals are not independent from each other, and the relationship of Expression (1) is established between the three types of transmission frequency intervals.

Here, the phase difference Δφ ₁ (f) and the phase difference Δφ ₂ (f) indicate the phase difference between the second and first, and the third and second Doppler signals, respectively. By detecting the frequency component satisfying the relationship of Expression (1) as the Doppler frequency, the Doppler frequency can be detected even when a clear peak does not appear when the Doppler signal is frequency-analyzed like a human being.

The Doppler frequency extraction unit 340 calculates the phase difference Δφ ₁ (f) and the phase difference Δφ ₂ (f from the phase θ ₁ (f), θ ₂ (f) of the complex spectrum of each of the first Doppler difference signal and the second Doppler difference signal. ) Will be described. The phase of the complex spectrum of each of the first Doppler difference signal and the second Doppler difference signal and the phase difference between the Doppler signals have a relationship shown in Expression (2).

Here, θ ₃ (f) indicates the phase of the complex spectrum of the third Doppler difference signal (the complex spectrum of the difference signal between the third Doppler signal and the first Doppler signal). In the above equation, the phase of the third Doppler difference signal is newly required. Here, from the respective complex spectrums of the first Doppler difference signal and the second Doppler difference signal, the third Doppler difference signal is used for convenience. A method for obtaining the complex spectrum of will be described.

The complex spectrum F _s3 (f) of the third Doppler difference signal (difference between the third Doppler signal and the first Doppler signal) is the complex spectrum of the first Doppler difference signal F _s1 (f) and the complex spectrum of the second Doppler difference signal. _Is calculated from Equation (3) using F _s2 (f).

Next, the phase characteristic of the first from the complex spectra of the three difference signals obtained third Doppler difference signal _{θ 1 (f), θ 2} (f), calculates theta ₃ to _(f).

Next, phase differences Δφ ₁ (f) and Δφ ₂ (f) are calculated from the calculated phase characteristics θ ₁ (f), θ ₂ (f), and θ ₃ (f) according to the above-described formula. If the cost is acceptable, an A / D converter or the like may be added to the hardware configuration of FIG. 1 so that the complex spectrum of the third Doppler difference signal can be directly measured.

Further, as is well known, in the Doppler radar device, when the phase difference between two Doppler frequencies becomes π or more, the result of the phase comparison becomes indeterminate, so that the calculated phase differences Δφ ₁ (f) and Δφ ₂ (f ) Is adjusted by adding / subtracting 2π so that it falls within the range of [−π, + π]. Two phase differences are obtained by the above processing.

Next, the Doppler frequency extraction unit 340 extracts a frequency including a signal component caused by the moving object as a Doppler frequency from the calculated phase difference. That is, since f ₁ is 244.15000 GHz, f ₂ is 24.15125 GHz, and f ₃ is 24.15375 GHz, the intervals are 1.25 MHz and 2.5 MHz, respectively, so that the phase difference Δφ ₂ (f) is Δφ ₁ It must be twice the value of (f).

Therefore, the Doppler frequency extraction unit 340 compares the result obtained by doubling the phase difference Δφ ₂ (f) and the phase difference Δφ ₁ (f), and sets the frequency component whose difference is equal to or less than a predetermined threshold as the Doppler frequency. Can be extracted.

  As for the Doppler frequency obtained here, one frequency component may be obtained when there is one moving object, but in the case of an object having a plurality of velocity components such as walking of a human body, a frequency composed of a plurality of frequency components is usually used. Obtained as a band.

The distance calculation unit 350 obtains the phase difference of each complex spectrum of the first Doppler difference signal and the second Doppler difference signal for each Doppler frequency, and calculates the distance to the moving object using the phase difference.

Specifically, for each Doppler frequency extracted by the Doppler frequency extraction unit 340, the distance to the moving object is calculated based on the calculated phase difference of each complex spectrum of the first Doppler difference signal and the second Doppler difference signal. To do. If the speed of light is c and the set of Doppler frequencies is F _d , the distance R (f) to the moving object can be obtained by equation (4). Equation (4) is the same as the equation for calculating the distance of the conventional two-frequency CW radar.

ここでＦ_ｄは抽出したドップラ周波数の集合を表す。

Here, F _d represents a set of extracted Doppler frequencies.

  The intensity distribution calculation unit 360 calculates the intensity of the original Doppler signal from the intensity of the first Doppler difference signal and the intensity of the second Doppler difference signal for each Doppler frequency, calculates the average value, and calculates the calculated average value for the distance. Corresponding to the distance calculated by the unit 350, the intensity distribution is calculated.

  Specifically, the complex spectrum of the first Doppler difference signal and the complex spectrum of the second Doppler difference signal are read for each Doppler frequency extracted by the Doppler frequency extraction unit 340, and the intensity of each read complex spectrum is calculated. Then, the intensity of the original Doppler signal is calculated.

Here, the estimated value of the intensity of the original Doppler signal is calculated by substituting into the equation (5) using the phase difference Δφ ₁ (f). Equation (5) can be derived using the addition theorem based on the fact that two Doppler signals and their difference signals can be expressed by trigonometric functions for each Doppler frequency, and the intensity of the original Doppler signal is It can be expressed using the phase difference between the intensity and the complex spectrum of two Doppler signals.

Further, since the intensity of the original Doppler signal can also be calculated from the phase difference Δφ ₂ (f) by the equation (6), the average value or the maximum value of the calculated estimated values of the two strengths is used as the intensity at each Doppler frequency. Also good.

  Further, when the difference between the two intensities is larger than a predetermined value, it is possible to exclude the frequency from the Doppler frequency because the possibility of noise is high.

  Further, when calculating the intensity distribution, attenuation due to distance may be corrected at the same time, and a frequency having a weak amplitude value equal to or less than a predetermined value may be excluded from the Doppler frequency.

  The velocity distribution calculation unit 370 calculates the velocity of the moving object for each Doppler frequency extracted by the Doppler frequency extraction unit 340, and calculates the velocity distribution by associating the calculated velocity with the distance calculated by the distance calculation unit 350 and the Doppler frequency. To do.

Specifically, when the Doppler frequency is f _d , the velocity v of the moving object can be obtained by Expression (7). In equation (7), the average value (f ₁ + f ₂ + f ₃ ) / 3 of the _three transmission frequencies is used to determine the speed of the Doppler frequency.

  The intrusion determination unit 380 determines whether the moving object is a person based on the intensity distribution calculated by the intensity distribution calculation unit 360 and the velocity distribution of the moving object calculated by the velocity distribution calculation unit 370, and determines that the person is a person. Then, it is determined that there is an intrusion.

  Specifically, clustering processing is performed in which the distances and intensities obtained at adjacent Doppler frequencies on the frequency axis are within a predetermined threshold and are regarded as the same moving object. Then, the center-of-gravity position, the average intensity, and the intensity dispersion value of the distance are obtained for each cluster regarded as the same moving object. Next, with reference to the velocity distribution, an average value and a variance value of velocity values corresponding to each distance value regarded as the same moving object are obtained. Finally, for each same moving object, the average value and variance value of the velocity value, the average value and the variance value of the intensity are subjected to a predetermined calculation to obtain the degree of humanity, and the humanity level is a predetermined threshold. If it is above, it is determined that there is an intrusion.

  The output unit 400 outputs a detection signal to the outside of the intrusion detection device when the intrusion determination unit 380 determines that there is an intrusion. The detection signal is input to a controller or the like (not shown) of the security system, and the controller performs display indicating intrusion detection or reporting to the security center via the communication line.

  In the present embodiment, the transmission frequency interval is set to 1: 2, but this is only an example, and it is of course possible to set the transmission frequency interval to be equal.

By setting equal intervals, the phase difference Δφ (f) used for distance measurement is set to the difference between the phase θ ₁ (f) of the first Doppler difference signal and the phase θ ₂ (f) of the second Doppler difference signal (θ ₂ (f) −θ ₁ (f)) can be obtained directly, so that there is an advantage that the amount of signal processing can be reduced.

  Further, when the transmission frequency interval is unequal, such as 1: N (N is a real number equal to or greater than 1), a plurality of maximum monitorable distances can be set. It becomes possible to simultaneously use the processing result according to the application such as setting that emphasizes the expansion of the detection distance.

Next, the reason for using the difference signal in this embodiment will be described.
First, with reference to FIG. 4, a case where the frequency analysis of the Doppler signal is performed without using the difference signal will be described. FIG. 4 is a diagram showing the waveform of a Doppler signal (left column) and its power spectrum (right column).

  FIG. 4A shows a case where a human is moving in a monitoring space about 3 m away from the sensor, and when looking at the power spectrum (right column), a relatively steep mountain-shaped waveform due to the person has a frequency of 100. You can see it in the vicinity. FIG. 4B shows a case in which a water droplet is falling in the immediate vicinity of the sensor. From the power spectrum (right column), it can be seen that a relatively gentle mountain waveform is generated due to the water droplet.

  However, as shown in FIG. 4C, when a person and a water drop enter at the same time, the signal resulting from the movement of the human is buried by the signal resulting from the water drop, as is apparent from the power spectrum. It turns out that it is difficult to distinguish water drops.

  Next, a case where a difference signal is calculated from a Doppler signal and frequency analysis is performed will be described with reference to FIG. FIG. 5 is a diagram showing the waveform of the first Doppler difference signal (left column) and its power spectrum (right column).

  FIG. 5A shows a case where a human is moving in a monitoring space about 3 m away from the sensor, which is the same as the case of FIG. FIG. 5B shows a case where a water drop is falling in the immediate vicinity of the sensor, but it can be seen that there is no peak in the power spectrum caused by the water drop. Furthermore, it can be seen that when a person and water droplets in FIG. 5C enter at the same time, only the power spectrum caused by the person appears as in FIG.

Further, the effect of obtaining the difference signal will be described with reference to FIG.
The phase difference between the two signals increases in accordance with the principle of the two-frequency CW method as the distance from the sensor increases. Further, the amplitude of the difference signal between two signals having substantially the same amplitude and frequency increases as the phase difference increases. Therefore, when the distance from the sensor is short, the phase difference between the two signals is small, so the amplitude of the difference signal is small. On the other hand, when the distance from the sensor is far, the amplitude of the difference signal increases because the phase difference between the two signals is large. That is, by taking the difference between the two signals, the effect of reducing the amplitude is obtained as the distance from the sensor is shorter.

  A theoretical value of the relationship between the amplitude of the difference signal and the distance from the sensor is shown in FIG. FIG. 6B shows the theoretical value of distance attenuation of the amplitude. As shown in FIG. 6B, the amplitude of the microwave is proportional to the fourth power of the distance from the sensor. Attenuates. The observed signal is the product of these two effects. FIG. 6C shows an amplitude value in the case of a difference signal considering distance attenuation, an amplitude value in the case of a Doppler signal, and a theoretical value of distance. As shown in FIG. 6C, in the case of a Doppler signal, 80 dB is required to observe a distance up to 10 m. However, if a difference signal is used, the dynamic range can be compressed by 30 dB. That is, rather than directly A / D converting the Doppler signal, the number of bits required for the A / D converter can be reduced by obtaining the difference signal and performing A / D conversion.

<Embodiment 2>
Hereinafter, a second embodiment in which a function for compensating the time variation of the oscillation frequency of the voltage controlled oscillator is added to the first embodiment will be described with reference to FIGS. The numbers in FIGS. 7 and 8 are the same as those in FIG. 1 and FIG. 2, and the description is simplified.

  As described above, in the case of an intrusion detection device, the detection target is mainly humans, and when a Doppler signal is subjected to frequency analysis, a clear peak does not appear as in a vehicle or the like. In order to discriminate, the Doppler frequency is extracted from the two calculated phase differences.

In the extraction of the Doppler frequency, the first embodiment assumes that the phase difference Δφ ₁ (f) and Δφ ₂ (f) maintain a certain relationship. The spacing ratio | f ₂ −f ₁ |: | f ₃ −f ₂ | needs to be kept constant. However, in practice, it is inevitable that the oscillation frequency of the voltage-controlled oscillator 120 changes with time due to temperature characteristics and the like. As described in the first embodiment, the frequency at which the ratio of the phase difference Δφ ₁ (f) and the phase difference Δφ ₂ (f) substantially matches the transmission frequency interval ratio is extracted as the Doppler frequency. When the interval ratio deviates from the initial setting value, the difference between the phase difference Δφ ₁ (f) and the phase difference Δφ ₂ (f) increases, which causes a problem that the Doppler frequency cannot be extracted correctly.

  Therefore, in the second embodiment, in order to correctly extract the Doppler frequency even when using a voltage controlled oscillator whose oscillation frequency varies somewhat due to temperature characteristics or the like, the ratio of the phase difference between Doppler signals is set in advance. A method of controlling to determine that the transmission frequency interval ratio has changed when it no longer matches the stored transmission frequency interval ratio and automatically adjust the transmission frequency interval will be described.

  FIG. 7 shows the configuration of the intrusion detection device according to the second embodiment of the present invention.

Similar to the first embodiment, the transmission unit 101 transmits continuous microwaves having _three different frequencies f ₁ , f ₂ , and f ₃ to the monitoring space in a time division manner.

The voltage value of the staircase wave is different from that of the first embodiment in that the frequency value of the microwave is defined and the voltage value defining f ₂ is adjusted based on the command value from the processing unit 301.

  Since the receiving unit 200 is the same as that of the first embodiment, description thereof is omitted.

  As in the first embodiment, the processing unit 301 is based on the complex spectrum of the first Doppler difference signal and the second Doppler difference signal from the digital data of the first Doppler difference signal and the second Doppler difference signal input from the receiving unit 200. The Doppler frequency extraction unit 340 extracts the Doppler frequency.

  In the present embodiment, a transmission frequency interval ratio calculation unit 342 that estimates the ratio of transmission frequency intervals from the phase difference in the extracted Doppler frequency, and calculates a voltage command value to be given to the transmission unit 101 based on the estimated transmission frequency interval ratio. A voltage command value calculation unit 344 is added.

The transmission frequency interval ratio calculation unit 342 includes the phase difference Δφ ₁ (f) between the second Doppler signal and the first Doppler signal at the Doppler frequency extracted by the Doppler frequency extraction unit 340, and the phase difference between the third Doppler signal and the second Doppler signal. The ratio of Δφ ₂ (f) is calculated. As the phase difference ratio, an average value is calculated when there are a plurality of Doppler frequency components.

The ratio F _R (f) between the phase difference Δφ ₁ (f) and the phase difference Δφ ₂ (f) at the Doppler frequency extracted by the transmission frequency interval ratio calculation unit 342 is calculated.
As one specific example, the ratio F _R (f) is calculated using Equation (8).

Then an average value _{F R} of the calculated ratio _F R (f), the formula (9) the difference _{S R} between the theoretical value calculated from the set value of the transmission frequency _{f 1,} f 2, _{f 3} Use to calculate.

An estimate of the spacing ratio of the transmission frequency by setting the F _R and S _R as described above in F _R, the error between the initial setting value can be evaluated by S _R. Incidentally, S _R when the frequency f ₂ is high negative and low is positive, its size is proportional to the deviation from the initial setting value, and supplies the voltage-controlled oscillator 120 by using the value command The voltage value can be adjusted by proportional control.

  As an example of a specific adjustment method, when the relationship between the input voltage of the voltage controlled oscillator 120 and the oscillation frequency is a monotonically increasing relationship (curve 600 in the figure) as illustrated in FIG. It is preferable to update the value by the equation (10) as a real constant.

In Expression (10), α is a coefficient for controlling the responsiveness of the voltage value, and is appropriately determined in advance while monitoring the voltage to the voltage controlled oscillator and the output frequency. If α is increased, the response becomes half-vibration, and if it is reduced, the response becomes worse, but it becomes easier to stabilize. The frequency of the transmission frequency can be adjusted by adjusting the voltage value based on Expression (10).

Note that the method of calculating the phase difference ratio and the method of updating the voltage value for adjusting the transmission frequency are merely examples, and other methods (for example, Δφ ₁ (f) / Δφ ₂ (f ), Or may be configured to adjust the transmission frequency f ₁ instead of adjusting the transmission frequency f ₂ .

When the voltage command value calculating section 344 compares the calculated transmission frequency interval ratio and the transmission frequency interval ratio set in advance at the transmission frequency interval ratio calculating unit 342, it reaches or exceeds the value the difference S _R is predetermined, An instruction for correcting the voltage waveform generated by the staircase wave generator 111 included in the transmission unit 101 is given.

  Each embodiment has been described as an intrusion detection device. However, the moving object for measuring the speed and distance according to the present invention is not limited to a human being, and can be applied to a device for measuring a vehicle or the like. . Moreover, although each said embodiment demonstrated as an intrusion detection apparatus using a microwave, this invention is not limited to a microwave, The radio wave or ultrasonic wave of other frequency bands, such as a millimeter wave The present invention can also be applied to an apparatus using light such as sound waves such as laser and laser.

1 is a schematic block configuration diagram of a moving object detection device according to Embodiment 1. FIG. FIG. 2 is a block configuration diagram illustrating a configuration of a processing unit of the moving object detection device according to the first embodiment. It is a figure which shows the staircase wave added to a transmission signal. It is a figure which shows the relationship between the waveform of a Doppler signal when the Doppler signal is directly frequency-analyzed without using a difference signal, and its power spectrum. It is a figure which shows the relationship between the waveform of a Doppler signal at the time of calculating a difference signal from a Doppler signal, and performing frequency analysis, and its power spectrum. It is a figure explaining the effect of distance attenuation by a difference signal. FIG. 5 is a schematic block configuration diagram of a moving object detection device according to a second embodiment. FIG. 5 is a block configuration diagram illustrating a configuration of a processing unit of a moving object detection device according to a second embodiment. It is a figure which shows the relationship between the input voltage of the voltage control type | mold oscillator 120, and an oscillation frequency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Transmission part 200 Reception part 300 Processing part 400 Output part

Claims (3)

Transmitting means for time-division transmitting a plurality of transmission waves having different frequencies to the monitoring space;
Receiving means for receiving a reflected wave with respect to the transmitted wave;
Doppler signal extraction means for extracting a Doppler signal from the transmission wave and its reflected wave for each transmission wave;
Difference signal generating means for generating a plurality of difference signals of the plurality of Doppler signals corresponding to the respective transmission waves;
Phase difference calculating means for calculating a phase difference between the plurality of difference signals;
Doppler frequency calculating means for calculating a Doppler frequency of the Doppler signal from the phase difference;
Intensity distribution calculating means for calculating an intensity distribution of reflection from a moving object from a distance based on the amplitude of the difference signal at the Doppler frequency and the phase difference at the Doppler frequency ;
Velocity distribution calculating means for calculating the velocity distribution of the moving object from the distance based on the phase difference at the Doppler frequency and the velocity at the Doppler frequency ;
Determination means for obtaining a mass regarded as the same moving object from the intensity distribution, and determining the presence or absence of the moving object as a detection target from the degree of likelihood of the detection target obtained for each same moving object with reference to the velocity distribution at the distance of the mass And a moving object detection device. The phase difference calculating means calculates at least a plurality of sets of the phase differences;
The Doppler frequency calculating means compares the plurality of sets of phase difference, the moving object detection apparatus according to a frequency band that nearly matches to claim 1 for extracting a Doppler frequency. Transmission frequency interval ratio calculating means for calculating a ratio of frequency intervals between the plurality of transmission waves based on the ratio of the plurality of sets of phase differences;
The frequency interval ratio calculated by the transmission frequency interval ratio calculating means is compared with a preset frequency interval ratio, and when a variation is detected without matching, the frequency interval ratio set in advance is set to the frequency of the transmission wave. The moving object detection apparatus according to claim 1, further comprising a correction instruction unit that gives an instruction to the transmission unit to perform correction so as to maintain .

Images