WO2022014011A1 - Object detecting equipment and object detecting method - Google Patents

Abstract

Object detecting equipment (1000) has a transmission unit (1001) and a reception unit (1101). The transmission unit (1001) transmits a synchronization signal at a reference timing established in advance and also transmits a predetermined detection signal at a transmission timing determined on the basis of the reference timing. The reception unit (1101) generates, upon detection of the synchronization signals from among received radio waves, receipt local oscillation signals on the basis of the timings of detection of the synchronization signals, generates intermediate frequency signals on the basis of the receipt local oscillation signals, and generates an image on the basis of the intermediate frequency signals.

Description

Object detection device and object detection method

The present invention relates to an object detection device and an object detection method for recognizing or identifying the existence of an object by irradiating the object with radio waves and detecting the radio waves reflected or radiated by the object.

Unlike light, radio waves (microwaves, millimeter waves, terahertz waves, etc.) have an excellent ability to pass through objects. Devices and sensing technology that image and inspect articles such as under clothes and inside bags by utilizing the ability to transmit radio waves have been put into practical use. A related technique is disclosed in Patent Document 1.

Patent Document 1 discloses an imaging device (object detection device) using radio waves, in which a transmitting device that transmits radio waves and a receiving device that receives radio waves are physically separated.

Specifically, Patent Document 1 discloses a configuration in which the transmitting device 301 and the receiving device 306 are physically separated as shown in the conceptual diagram of FIG. 23. In imaging apparatus shown in FIG. 23, the transmitting apparatus 301, transmitting antenna _{302 1,} 302 2, ..., toward the radio 304 to the object 303 from one or more antennas 302 _m of the 302 _M transmission do. The radio wave 304 is reflected by the object 303, and reflected waves 305 ₁ , 305 ₂ , ..., 305 _N are generated. The generated reflected waves 305 ₁ , 305 ₂ , ..., 305 _N are received by the receiving antennas 307 ₁ , 307 ₂ , ..., 307 _N provided in the receiving device 306. Then, the amplitude of the radio wave reflected by the object 303 is calculated based on _{the reflected waves 305 1} , 305 ₂ , ..., 305 _N received by the receiving device 306. By imaging the distribution of the amplitude of the radio wave, an image of the object 303 can be obtained.

In the case of this configuration, as shown in the conceptual diagram of FIG. 24, the transmitting device 301 and the receiving device 306 are connected to the same oscillating unit 401, and the detection signal generated by the same oscillating unit 401 is received.

The transmitter 301 transmits the radio wave that carries the detection signal generated by the oscillator 401 by the transmitting antenna 302 via the transmitter 404. The transmitter 404 is implemented by an IC or a module.

The receiving device 306 includes a receiving antenna 307, a receiver 405 including a mixer 402, and a data transfer unit 403. The receiver 405 is implemented by an IC or a module. The mixer 402 in the receiving device 306 mixes the reflected wave 305 from the object 303 received by the receiving antenna 307 and the detection signal generated by the oscillating unit 401 to obtain an intermediate frequency signal (hereinafter, “IF”). (Intermediate Frequency) signal "may be written.) Is generated. The IF signal generated by the mixer 402 is output to the data transfer unit 403. The IF signal output to the data transfer unit 403 is used for calculating the amplitude of the radio wave reflected by the object 303 and generating an image of the object 303. In FIG. 24, a cable that connects the oscillator 401 and each of the transmitter 404 and the receiver 405 and transmits a signal is represented by a double line.

Transmission by using the same signal generated by the same oscillator as the detection signal carried by the radio wave transmitted from the transmitting device and the detection signal used to generate the IF signal in the receiving device. It is possible to eliminate the fluctuation of the phase difference of the detection signal used by the device and the receiving device, and suppress the deterioration of the image quality of the image of the object 303 due to the fluctuation of the phase difference.

Patent No. 5358053

As shown in FIG. 24, the detection signal carried by the radio wave transmitted from the transmitting device and the detection signal used for generating the IF signal in the receiving device are the same generated by the same oscillator. When using a signal, it is necessary to connect each of the transmitting device and the receiving device to the same oscillator via a wiring cable. In this case, problems such as "the wiring cable interferes with the pedestrian" and "the arrangement of the transmitting device and the receiving device is restricted by the wiring cable" may occur.

Therefore, the present inventors have studied a configuration in which a detection signal carried by a radio wave transmitted from a transmitting device and a detection signal used for generating an IF signal in the receiving device are generated by separate oscillators. did. By adopting this configuration, the above problem is solved. However, when adopting this configuration, it is necessary to synchronize the processing of the transmitting device and the receiving device.

The present invention has a configuration in which a detection signal carried by radio waves transmitted from a transmitting device and a detection signal used for generating an IF signal in the receiving device are generated by separate oscillating units, and the transmitting device and the receiving device are used. An object of the present invention is to provide a technique for synchronizing processing with an apparatus.

According to the present invention
It is an object detection device for detecting objects by radio waves.
It is equipped with a transmitting means and a receiving means.
The transmission means is
A transmitting antenna that transmits radio waves, and
The transmission antenna transmits a radio wave that carries a predetermined detection signal at a synchronization signal transmission process that transmits a radio wave that carries a synchronization signal at a preset reference timing from the transmission antenna and a transmission timing that is determined based on the reference timing. Transmission oscillation means that executes detection signal transmission processing to be transmitted from
Have,
The receiving means
The receiving antenna that receives radio waves and
A synchronization signal detection means for detecting the synchronization signal from the radio waves received by the reception antenna, and
A receive oscillation means that generates a receive local oscillation signal based on the timing at which the synchronization signal is detected, and a receive oscillation means.
A receiver that generates an intermediate frequency signal based on the detected signal detected from the radio waves received by the receiving antenna and the received local oscillation signal.
An arithmetic means for generating an image based on the intermediate frequency signal, and
An object detection device having the above is provided.

Further, according to the present invention,
It is an object detection method executed by an object detection device that has a transmission means and a reception means and is used to detect an object by radio waves.
The transmission means is
Synchronous signal transmission processing to transmit radio waves that carry a synchronization signal from a transmission antenna at a preset reference timing, and radio waves that carry a predetermined detection signal from the transmission antenna at a transmission timing determined based on the reference timing. Executes the detection signal transmission process to be transmitted,
The receiving means
The synchronization signal is detected from the radio waves received by the receiving antenna, and the synchronization signal is detected.
A received local oscillation signal is generated based on the timing at which the synchronization signal is detected.
An intermediate frequency signal is generated based on the detection signal detected from the radio waves received by the reception antenna and the reception local oscillation signal.
An object detection method for generating an image based on the intermediate frequency signal is provided.

According to the present invention, in a configuration in which a detection signal carried by a radio wave transmitted from a transmitting device and a detection signal used for generating an IF signal in the receiving device are generated by separate oscillators, the transmitting device is used. A technology for synchronizing the processing between the receiver and the receiver is realized.

FIG. 1 is a configuration diagram showing an example of the configuration of the object detection device according to the present embodiment. FIG. 2 is a diagram illustrating an example of a method of controlling the frequency of a radio wave transmitted by a transmitting unit in the present embodiment. FIG. 3 is a diagram illustrating an example of a method of controlling the frequency of a radio wave transmitted by a transmitting unit in the present embodiment. FIG. 4 is a diagram illustrating an example of a control method of a detection signal transmitted by the transmitting unit and a LO signal generated by the receiving unit in the present embodiment. FIG. 5 is an example of a flowchart showing an object detection method according to the present embodiment. FIG. 6 is an example of a flowchart showing the object detection method in the present embodiment. FIG. 7 is an example of a flowchart showing the object detection method in the present embodiment. FIG. 8 is a diagram showing the result of imaging the radio wave amplitude distribution of the reflected wave from the object by the conventional method. FIG. 9 is a diagram showing the result of imaging the radio wave amplitude distribution of the reflected wave from the object in the present embodiment. FIG. 10 is a configuration diagram showing an example of the configuration of the object detection device of the present embodiment. FIG. 11 is a configuration diagram showing an example of the hardware configuration of the object detection device of the present embodiment. FIG. 12 is a configuration diagram showing an example of the configuration of the object detection device of the present embodiment. FIG. 13 is an example of a flowchart showing the object detection method according to the present embodiment. FIG. 14 is an example of a flowchart showing the object detection method according to the present embodiment. FIG. 15 is a configuration diagram showing an example of the configuration of the object detection device of the present embodiment. FIG. 16 is a diagram illustrating an example of a method of controlling the frequency of radio waves transmitted by the transmitting unit in the present embodiment. FIG. 17 is an example of a sequence diagram showing an object detection method according to the present embodiment. FIG. 18 is an example of a sequence diagram showing an object detection method according to the present embodiment. FIG. 19 is an example of a sequence diagram showing an object detection method according to the present embodiment. FIG. 20 is an example of a sequence diagram showing an object detection method according to the present embodiment. FIG. 21 is an example of a sequence diagram showing an object detection method according to the present embodiment. FIG. 22 is a diagram illustrating an example of a method for controlling the frequency of radio waves transmitted by the transmitting unit in the present embodiment. FIG. 23 is a configuration diagram showing an example of the configuration of the object detection device of the comparative example. FIG. 24 is a configuration diagram showing an example of the configuration of the object detection device of the comparative example.

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. In each of the drawings shown below, the same or corresponding parts will be indicated by the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1 of the present embodiment)
[Device configuration]
First, the configuration of the object detection device according to the first embodiment will be described with reference to FIG.

The object detection device 1000 in the first embodiment shown in FIG. 1 is a device for detecting an object by radio waves. As shown in FIG. 1, the object detection device 1000 includes a transmission unit 1001 and a reception unit 1101.

The transmission unit 1001 transmits a radio wave that carries a detection signal toward an object to be detected (hereinafter referred to as an "object") 1201. The receiving unit 1101 receives the radio wave reflected by the object 1201 or the radio wave radiated from the object 1201.

The transmission unit 1001 includes a transmission antenna 1002, a transmitter 1004 including a transmission oscillation unit 1003, and a control unit 1005. It is desirable that the transmitter antenna 1002 and the transmitter 1004 are integrally mounted by an IC or a module. In the first embodiment, the transmitter 1004 provided with the transmission oscillation unit 1003 and the transmission antenna 1002 are mounted by an IC or a module, and the transmission oscillation unit 1003 and the transmission antenna 1002 are connected by wiring in the IC or the module. do. In this case, the wiring cable for supplying radio waves becomes unnecessary. Unlike the conventional object detection device, in the first embodiment, the wiring cable for supplying radio waves is not required in the transmission unit 1001, so that the device cost can be reduced and the housing size can be reduced.

In the transmission unit 1001, the transmission oscillation unit 1003 in the transmitter 1004 outputs radio waves toward the transmission antenna 1002. The transmitter 1004 may have a function of amplifying or attenuating the radio wave output from the transmission oscillation unit 1003 to a predetermined value. The transmitting antenna 1002 transmits the radio wave output from the transmitter 1004 toward the object 1201. At this time, the transmission of the radio wave from the transmitting antenna 1002 may be performed in a time division manner in which _{the transmitting antennas 1002 1} , 1002 ₂ , ..., 1002 _{N are switched.}

In the transmitter 1001, the control unit 1005 controls the transmission oscillation unit 1003 in the transmitter 1004. Specifically, the control unit 1005 controls the amplitude and frequency of the radio wave output from the transmission oscillation unit 1003.

The receiving unit 1101 includes a receiving antenna 1102, a receiving oscillation unit 1103, a receiver 1104 including a mixer 1105, a data transfer unit 1106, a calculation unit 1107, a synchronization signal detection unit 1109, and a control unit 1110. There is. It is desirable that the receiving antenna 1102 and the receiver 1104 are integrally mounted by an IC or a module. Further, the arithmetic unit 1107 may be physically and / or logically separated from the receiving unit 1101, or may be physically and logically integrated.

In the receiving unit 1101, the receiving antenna 1102 receives radio waves. For example, the receiving antenna 1102 receives radio waves reflected by the object 1201 and radio waves radiated from the object 1201. Hereinafter, the radio waves reflected by the object 1201 and the radio waves radiated from the object 1201 are collectively referred to as "radio waves from the object 1201". At this time, the radio wave from the object 1201 may be received by a _{plurality of receiving antennas 1102 1} , 1102 ₂ , ... 1102 _N. The radio wave received by the receiving antenna 1102 is output to the receiver 1104.

In the receiving unit 1101, the receiving oscillation unit 1103 outputs a local oscillation signal (Local Oscillator signal, hereinafter referred to as "LO signal") toward the receiver 1104. The reception oscillation unit 1103 generates a signal by the same algorithm as the transmission oscillation unit 1003. Therefore, the detection signal generated by the transmission oscillation unit 1003 and the LO signal generated by the reception oscillation unit 1103 have the same contents. Further, by aligning the signal generation timings in the synchronization processing, the transmission oscillation unit 1003 and the reception oscillation unit 1103 are configured to generate the same signal at the same timing. A wiring cable for radio wave supply is used for the connection between the reception oscillator 1103 and the receiver 1104 shown by the double line in FIG.

In the receiving unit 1101, the mixer 1105 in the receiver 1104 mixes the radio wave output from the receiving antenna 1102 and the LO signal output from the receiving oscillation unit 1103 to generate an intermediate frequency signal (IF signal) and generate it. The IF signal is output to the data transfer unit 1106.

In the receiving unit 1101, the data transfer unit 1106 outputs an IF signal to the arithmetic unit 1107. The data transfer unit 1106 may convert the IF signal output from the receiver 1104 into a digital signal and output it to the calculation unit 1107.

The calculation unit 1107 calculates the distribution of radio waves from the object 1201 based on the IF signal output from the data transfer unit 1106. Further, an image of the object 1201 is generated based on the distribution of radio waves from the object 1201. The details of the operation of the calculation unit 1107 will be described in the section [Device operation] described later.

In the receiving unit 1101, the control unit 1110 controls the receiving oscillation unit 1103. Specifically, the control unit 1110 controls the amplitude and frequency of the LO signal output from the reception oscillation unit 1103.

In the first embodiment, unlike the form of the comparative example shown in FIGS. 23 and 24, the transmission oscillation unit 1003 of the transmission unit 1001 and the reception oscillation unit 1103 of the reception unit 1101 are separately provided (physical). It is divided into objective and logical).

The feature that the transmission oscillation unit 1003 of the transmission unit 1001 and the reception oscillation unit 1103 of the reception unit 1101 are separately provided eliminates the need for a wiring cable between the transmission unit 1001 and the reception unit 1101. Since there is no wiring cable between the transmitting unit 1001 and the receiving unit 1101, which is an area through which pedestrians pass, the wiring cable does not obstruct the passage of pedestrians in the first embodiment. Further, since there is no wiring cable between the transmitting unit 1001 and the receiving unit 1101, it is possible to flexibly change the positional relationship between the transmitting unit 1001 and the receiving unit 1101.

In the first embodiment, the frequency 1301 of the detection signal carried by the radio wave transmitted from the transmission unit 1001 may be swept. At this time, the control unit 1005 in the transmission unit 1001 controls the transmission oscillation unit 1003 so as to sweep the frequency 1301 of the detection signal.

As shown in FIG. 2, the method of sweeping the frequency 1301 of the detection signal may be a stepped frequency continuous wave (SFW) method of sweeping at discrete frequency values according to time. Alternatively, as shown in FIG. 3, the method of sweeping the frequency 1301 of the detection signal may be a frequency modulation continuous wave (FMCW) method in which the frequency 1301 is swept with a continuous frequency value according to the time.

When sweeping the frequency 1301 of the detection signal, the frequency 1302 of the LO signal generated by the reception oscillation unit 1103 is also swept in the same manner. Then, the object detection device 1000 of the first embodiment performs the following synchronization processing in order to generate the detection signal and the LO signal of the same frequency at the same timing.

In the first embodiment, the transmitting unit 1001 transmits a radio wave carrying a synchronization signal toward the receiving unit 1101. As a specific operation in the transmission unit 1001, the control unit 1005 controls the transmission oscillation unit 1003 in the transmitter 1004 to generate a radio wave that carries a synchronization signal. The transmitter 1004 outputs a radio wave carrying a synchronization signal to the transmitting antenna 1002. The transmission antenna 1002 transmits radio waves that carry the synchronization signal from the transmission unit 1001.

The receiving unit 1101 receives the radio wave that carries the synchronization signal at the receiving antenna 1102. The radio wave received by the receiving antenna 1102 is output to the synchronization signal detection unit 1109. The synchronization signal detection unit 1109 demodulates the radio wave and detects the synchronization signal. The synchronization signal detection unit 1109 outputs the detected synchronization signal to the control unit 1110. The control unit 1110 controls the reception oscillation unit 1103 based on the synchronization signal output from the synchronization signal detection unit 1109. _{When any one of} the receiving antennas 1102 1, 1102 ₂ , ... 1102 _N receives a radio wave that carries a synchronization signal, the above operation can be performed.

For example, at time t _t shown in FIG. 4, the transmission unit 1001 a radio wave carrying a synchronization signal, and transmits to the receiving unit 1101. Then, the receiving unit 1101 receives the radio wave, demodulates the radio wave, and detects the synchronization signal. Since the speed of the radio wave is high and the time required for the reception unit 1101 to detect the synchronization signal is sufficiently short, the timing at which the transmission unit 1001 transmits the radio wave carrying the synchronization signal and the reception unit 1101 transmit the synchronization signal. the detected timing may be regarded as the same time t _t.

Transmission unit 1001, at the timing of time t _s1 the predetermined time set in advance from the time t _t has passed, starts the sweep of the frequency 1301 of the detection signal from a predetermined value. Similarly, the receiving unit 1101, at the timing of time _{t s1} the predetermined time set in advance from the time _{t t} has passed, starts the sweep of the frequency 1302 of the LO signal from a predetermined value. The transmitting unit 1001 and the receiving unit 1101 generate a detection signal and an LO signal by the same algorithm. Therefore, by aligning the signal generation timings in the synchronization process, the transmission unit 1001 and the reception unit 1101 generate signals of the same frequency at the same timing. The synchronization process will be described in more detail in the following embodiments.

In the first embodiment, it is possible to generate an IF signal necessary for generating an image of an object 1201 in a state where there is no wiring between the transmitting unit 1001 and the receiving unit 1101.

However, only in the device configuration of the object detection device 1000 shown in FIG. 1, the phase difference between the detection signal transmitted from the transmission unit 1001 and the LO signal output from the reception oscillation unit 1103 in the reception unit 1101 is controlled. Is difficult. For example, when the transmitter 1004 in the transmission unit 1001 is switched or the frequency of the detection signal transmitted from the transmission unit 1001 is switched, the phase of the detection signal transmitted from the transmission unit 1001 is the reception oscillation in the reception unit 1101. It fluctuates regardless of the phase of the LO signal output from unit 1103. Such fluctuations in the phase difference between the detection signal transmitted from the transmission unit 1001 and the LO signal output from the reception oscillation unit 1103 in the reception unit 1101 cause the image of the object 1201 to be disturbed.

In the first embodiment, as described in the following [Device operation], the phase difference between the detection signal transmitted from the transmission unit 1001 and the LO signal output from the reception oscillation unit 1103 in the reception unit 1101 fluctuates. Also, an image generation method for stably generating a correct image of the object 1201 is provided.

[Device operation]
FIG. 5 is a flow chart showing the operation of the object detection device according to the first embodiment of the present invention. Further, in the first embodiment, the object detection method is implemented by operating the object detection device 1000. Therefore, the description of the object detection method in the first embodiment is replaced with the following description of the operation of the object detection device 1000.

As shown in FIG. 5, first, the synchronization signal is transmitted from the transmission unit 1001 (step A1).

Next, the receiving unit 1101 receives the synchronization signal transmitted from the transmitting unit 1001 (step A2).

The transmission / reception of the synchronization signal in steps A1 and A2 is output from the frequency 1301 of the detection signal transmitted from the transmission unit 1001 and the reception oscillation unit 1103 in the reception unit 1101 as described in the section of [Device Configuration]. It is a synchronization process for matching the frequency 1302 of the LO signal to be performed. The details of the synchronization process will be described in the following embodiments.

After the synchronization process is completed, the transmission unit 1001 transmits a radio wave that carries a detection signal toward the object 1201 (step A3).

Next, the radio wave from the object 1201 is received by each receiving antenna 1102 of the receiving unit 1101 (step A4).

Next, an IF signal is generated from the radio waves received by each receiving antenna 1102 of the receiving unit 1101 (step A5).

Next, the calculation unit 1107 calculates the distribution (image) of the radio wave from the object 1201 based on the IF signal (step A6). After that, object detection using this image can be performed. Means for detecting an object from an image are widely known. For example, an object can be detected based on the appearance characteristics (shape, size, etc.) of the object in the image. Examples of the object detection method include, but are not limited to, pattern matching and the use of a classifier generated by machine learning.

FIG. 6 is a flow chart showing the details of step A6 in which the calculation unit 1107 calculates the distribution (image) of the radio wave from the object 1201 based on the IF signal. As shown in FIG. 6, step A6 in which the calculation unit 1107 calculates the distribution (image) of the radio wave from the object 1201 based on the IF signal is composed of steps B1 to B7.

The step A6 for calculating the distribution (image) of the radio wave from the object 1201 based on the IF signal, which is shown in detail in FIG. 6, is the detection signal transmitted from the transmission unit 1001 and the LO signal generated in the reception unit 1101. Even if there is an indefinite phase difference that fluctuates at the time of measurement, the distribution (image) of the radio wave from the object 1201 is stably and correctly calculated.

As shown in FIG. 6, in step A6 for calculating the distribution (image) of the radio wave from the object 1201 based on the IF signal, the calibration parameter peculiar to the measurement system is calculated as a preprocessing before the measurement. Pre-processing before measurement includes step B3 for calculating the wave number axis calibration term and step B6 for calculating the transmitting antenna axis calibration term.

In the first embodiment, apart from the problem that the phase difference between the detection signal transmitted from the transmission unit 1001 and the LO signal output from the reception oscillation unit 1103 in the reception unit 1101 fluctuates, the arrangement of the transmission antenna 1002 and the reception A fixed error occurs depending on the arrangement of the antenna 1102 and the setting of the frequency 1301 of the detection signal transmitted from the transmission unit 1001. In order to calibrate this fixed error, step B3 for calculating the wave number axis calibration term and step B6 for calculating the transmitting antenna axis calibration term are performed.

Further, as shown in FIG. 6, in step A6 for calculating the distribution (image) of the radio wave from the object 1201 based on the IF signal, as the processing at the time of measurement, the error that fluctuates for each measurement is corrected and the object 1201 is used. Generates the distribution (image) of radio waves. The processing at the time of measurement is composed of steps B1 to B2, steps B4 to B5, and step B7. In steps B1 to B2, steps B4 to B5, and step B7, while correcting the fluctuation of the phase difference between the detection signal transmitted from the transmission unit 1001 and the LO signal output from the reception oscillation unit 1103 in the reception unit 1101, the target is simultaneously targeted. Generates a distribution (image) of radio waves from object 1201.

Next, the details of the steps shown in FIG. 6 will be described.

[Step B1]
In step B1 shown in FIG. 6, the IF signals s (m, n, q) output from the data transfer unit 1106 to the calculation unit 1107 are used. Here, m, n, and q represent the number of the transmitting antenna 1002, the number of the receiving antenna 1102, and the number of the wave number, respectively. When the frequency 1301 of the detection signal transmitted from the transmission unit 1001 is f, there is a relationship of k = 2πf / c between the wave number k and the frequency f, where c is the speed of light. It is assumed that the IF signal is obtained for a set (m, n, q) of a transmitting antenna 1002, a receiving antenna 1102, and a wave number (that is, frequency). _{In step B1, the image PRX} (m, q, r) is obtained by calculating the correlation sum of the receiving antenna axes based on the following equation (1) using the IF signal s (m, n, q). Generate.

In equation (1), r is a position in space. The image _PRX (m, q, r) represents the image intensity at the position r in space. The image _PRX (m, q, r) is also an amount obtained for each set of the number m of the transmitting antenna 1002 and the number q of the wave number. Rt (m, r) represents the distance between the transmitting antenna 1002 corresponding to the number m and the position r. Further, Rr (n, r) represents the distance between the receiving antenna 1102 corresponding to the number n and the position r. j is an imaginary unit.

[Step B2]
_{In the next step B2, the correction term c Δθ [WN]} (m, q) on the wave number axis of the indefinite phase difference between the detection signal and the LO signal is obtained in step B1 based on the following equation (2). _{Calculated from RX} (m, q, r).

In equation (2), q'is a wavenumber different from q, and q'may be arbitrary. It is desirable that the wave numbers k corresponding to q'and q take close values.

Hereinafter, the reason why the correction term c _{Δθ [WN]} (m, q) is obtained by the equation (2) will be described. As described above, when the transmitter 1004 in the transmission unit 1001 is switched or the frequency of the detection signal transmitted from the transmission unit 1001 is switched, the phase of the detection signal transmitted from the transmission unit 1001 is in the reception unit 1101. It fluctuates regardless of the phase of the LO signal output from the reception oscillation unit 1103 of. At this time, the phase difference between the detection signal transmitted from the transmission unit 1001 and the LO signal in the reception unit 1101 can be expressed by a phase Δθ (m, q) that randomly fluctuates with respect to the transmission number m and the wave number q. In the receiving unit 1101 shown in FIG. 1, since the LO signal is supplied from the common receiving oscillation unit 1103 to _{the plurality of receivers 11041 1} , 1104 ₂ , and 1104 _{N, the phase Δθ is the number of the receiving antenna 1102.} It has no dependency on n. Due to this randomly fluctuating phase Δθ (m, q), the phase of the image _PRX (m, q, r) is shifted by Δθ (m, q). Here, consider two images _PRX (m, q, r) and _PRX (m, q', r) having different wavenumbers q. In the absence of the randomly fluctuating phase Δθ (m, q), the phases of the two images _PRX (m, q, r) and _PRX (m, q', r) do not change much. From _{this, P RX (m, q '} , r) correction term c _{[Delta] [theta]} in _[WN] (m, q) when the phase correction by _{multiplying, P RX (m, q,} r) and _P RX (m , Q', r) c _{Δθ [WN]} (m, q) It is desirable that the phases match. _{If the phases of PRX} (m, q, r) and _PRX (m, q', r) c _{Δθ [WN]} (m, q) match, then _PRX (m, q, r) + _PRX ( The absolute value of m, q', r) c _{Δθ [WN]} (m, q) is maximized. _PRX (m, q, r) + _PRX (m, q', r) c _{Δθ [WN] The correction term c Δθ [WN]} (m, q) under the condition of maximizing the absolute value of (m, q). The result of determining is given by the equation (2).

[Step B3]
In the next step B3, the wave number axis calibration term c _{A [WN]} (m, q) is calculated before the measurement. The detailed procedure of this step B3 will be described later in FIG.

[Step B4]
In the next step B4, the image _PRX (m, q, r) _{obtained in step B1, the correction term c Δθ [WN]} (m, q) obtained in step B2, and the calibration term c obtained in step B3. _{Using the three A [WN] (m, q), the image P WN} (m, r) is generated by the correlation sum of the wavenumber axes in the following equation (3).

[Step B5]
In the next step B5, the correction term c _{[Delta] [theta]} on the transmit antenna axis indefinite phase difference detection signal and the LO signal _{[TX] (m)} The following image P _WN obtained in step B4 based on equation (4) Calculate from (m, r).

In the formula (4), m'is an antenna number different from m, and m'may be arbitrarily taken. It is desirable that the transmitting antennas corresponding to m'and m are located close to each other. The equation (4) is the same as the equation (2), _{with the correction term c Δθ under the} condition of maximizing the absolute value of _{P WN} (m, r) + P _WN (m', r) c _{Δθ [TX] (m). [TX]} (m) has been determined.

[Step B6]
In the next step B6, the transmitting antenna axis calibration term c _{A [TX]} (m) is calculated before the measurement. The detailed procedure of this step B6 will be described later in FIG.

[Step B7]
In the next step B7, the image P _WN (m, r) _{obtained in step B4, the correction term c Δθ [TX]} (m) obtained in step B5, and the calibration term c _{A [TX] obtained in step B6.} Using the three (m), the image P (r) is generated by the correlation sum of the wavenumber axes in the following equation (5).

The image P (r) given by the equation (5) is an object obtained by correcting the randomly fluctuating phase difference Δθ (m, q) between the detection signal transmitted from the transmission unit 1001 and the LO signal in the reception unit 1101. It is an image showing the distribution of radio waves from the object 1201.

FIG. 7 shows step B3 in which the wave number axis calibration term c _{A [WN]} (m, q) is calculated before measurement, and _{step B6 in which the transmit antenna axis calibration term c A [TX]} (m) is calculated before measurement. It is a flow chart which showed the details. The flow chart shown in FIG. 7 is composed of steps C0 to C6. It should be noted that each step shown in FIG. 7 is performed by numerical calculation, not by actual measurement. However, the arrangement of the transmitting antenna 1002 used in the actual measurement, the arrangement of the receiving antenna 1102, and the setting of the frequency 1301 of the detection signal transmitted from the transmitting unit 1001 are also used in the numerical calculation performed in each step of FIG.

Next, the details of the steps shown in FIG. 7 will be described.

[Step C0]
In step C0 shown in FIG. 7, the IF signal s (m, n, q) when the calibration object is the object 1201 is numerically calculated based on the following equation (6).

In equation (6), σ (r) is the reflection intensity of the calibration object at the position r. It is desirable to use a plate-shaped reflector as large as possible for the calibration object. Further, in the equation (6), Rt (m, r) represents the distance between the transmitting antenna 1002 corresponding to the number m and the position r. Further, Rr (n, r) represents the distance between the receiving antenna 1102 corresponding to the number n and the position r. Further, k (q) represents the wave number k corresponding to the number q.

[Step C1]
_{Next, in step C1, the image PRX} (m, q, r) is calculated based on the equation (1) as in step B1 by using the IF signal obtained by the equation (6).

[Step C2]
Next, in step C2, the _{correction term c Δθ [WN]} (m, q) is corrected based on the equation (2) as in step B2, using _{the image PRX (m, q, r) calculated in step C1.} calculate.

[Step C3]
Next, in step C3, the _{wave number axis calibration term c A [WN]} (m, q) is _{calculated from the correction term c Δθ [WN]} (m, q) obtained in step C2 based on the following equation (7). calculate.

The wavenumber axis calibration term c _{A [WN]} (m, q) calculated by equation (7) is used in step B3 of FIG.

[Step C4]
Next, in step C3, the image _PRX (m, q, r) obtained in step C1, the correction term c _{Δθ [WN]} (m, q) obtained in step C2, and the wave number axis obtained in step C3. Using the calibration term c _{A [WN] (m, q), the image P WN} (m, r) is calculated based on the equation (3) as in step B4.

[Step C5]
Next, in step C5, the _{correction term c Δθ [TX]} (m) is calculated based on the equation (4) as in step B5, using _{the image P WN (m, r) calculated in step C4.}

[Step C6]
Next, in step C6, the _{wave number axis calibration term c A [TX]} (m) is calculated _{from the correction term c Δθ [TX]} (m) obtained in step C5 based on the following equation (8).

The wave number axis calibration term c _{A [TX]} (m) calculated by the equation (8) is used in step B6 of FIG.

This concludes the explanation of device operation. Even when the phase difference between the detection signal transmitted from the transmission unit 1001 and the LO signal output from the reception oscillation unit 1103 in the reception unit 1101 fluctuates due to the above device operation, the correct image of the object 1201 is stabilized. An image generation method for generating the image is provided.

The correction terms c _{Δθ [WN]} (m, q) and c _{Δθ [TX]} (m) described above, and the calibration terms c _{A [WN]} (m, q) and c _{A [TX]} (m). Is all 1 regardless of the arguments m and q, which corresponds to the conventional image generation method without correction and calibration.

FIG. 8 shows a conventional image generation method in which correction and calibration are not performed when the phase difference between the detection signal transmitted from the transmission unit 1001 and the LO signal output from the reception oscillation unit 1103 in the reception unit 1101 fluctuates. An example of generating an image of a square object 1201 is shown. In FIG. 8, the position of the object 1201 is shown in the broken line in the center of the image, but the actually obtained image of the object 1201 is greatly deviated from the original square.

In FIG. 9, when the phase difference between the detection signal transmitted from the transmission unit 1001 and the LO signal output from the reception oscillation unit 1103 in the reception unit 1101 fluctuates, correction and calibration are performed based on the first embodiment. An example in which an image of a square object 1201 is generated by the image generation method carried out is shown. In FIG. 9, an image of the object 1201 is generated at the position of the object 1201 (inside the broken line in the center of the image) without being greatly collapsed.

(Modification 1 of the first embodiment)
FIG. 10 shows a diagram of the device configuration in the first modification of the first embodiment. In the apparatus configuration of the first embodiment shown in FIG. 1, the transmitting unit 1001 and the receiving unit 1101 are housed in different housings, but as in the modified example 1 of the present embodiment 1 shown in FIG. The transmitting unit 1001 and the receiving unit 1101 may be housed in the same housing and used as the object detection device 1000.

In FIG. 10, the transmitting antenna 1002 connected to the transmitter 1004 and the receiving antenna 1102 connected to the receiver 1104 are separated. On the other hand, the transmitter 1004 and the receiver 1104 may be connected to the same antenna via a switch or an isolator for switching transmission / reception, and may share the same antenna for transmission / reception.

Since the device operation in the first modification of the first embodiment is the same as the device operation in the first embodiment, the description thereof will be omitted.

[Hardware configuration]
Here, a computer (arithmetic logic unit) that realizes an object detection device by executing the program according to the first embodiment will be described with reference to FIG. FIG. 11 is a block diagram showing an example of a computer that realizes the object detection device 1000 according to the first embodiment.

As shown in FIG. 11, the computer 110 includes a CPU 111, a main memory 112, a storage device 113, an input interface 114, a display controller 115, a data reader / writer 116, and a communication interface 117. Each of these parts is connected to each other via a bus 121 so as to be capable of data communication.

The CPU 111 expands the program (code) in the first embodiment stored in the storage device 113 into the main memory 112, and executes these in a predetermined order to perform various operations. The main memory 112 is typically a volatile storage device such as a DRAM (Dynamic Random Access Memory). Further, the program according to the first embodiment is provided in a state of being stored in a computer-readable recording medium 120. The program in the first embodiment may be distributed on the Internet connected via the communication interface 117.

Further, specific examples of the storage device 113 include a semiconductor storage device such as a flash memory in addition to a hard disk drive. The input interface 114 mediates data transmission between the CPU 111 and an input device 118 such as a keyboard and mouse. The display controller 115 is connected to the display device 119 and controls the display on the display device 119. The computer 110 may include a GPU (Graphics Processing Unit) or an FPGA (Field-Programmable Gate Array) in addition to the CPU 111 or in place of the CPU 111.

The data reader / writer 116 mediates the data transmission between the CPU 111 and the recording medium 120, reads the program from the recording medium 120, and writes the processing result in the computer 110 to the recording medium 120. The communication interface 117 mediates data transmission between the CPU 111 and another computer.

Specific examples of the recording medium 120 include a general-purpose semiconductor storage device such as CF (CompactFlash (registered trademark)) and SD (SecureDigital), a magnetic recording medium such as a flexible disk, or a CD-. Examples include optical recording media such as ROM (CompactDiskReadOnlyMemory).

The object detection device in the first embodiment can be realized by using the hardware corresponding to each part instead of the computer in which the program is installed. Further, the object detection device may be partially realized by a program and the rest may be realized by hardware.

[effect]
Hereinafter, the effect of the first embodiment will be described. In the first embodiment, by using different oscillators for the transmission oscillation unit 1003 of the transmission unit 1001 and the reception oscillation unit 1103 of the reception unit 1101, the detection signal transmitted from the transmission unit 1001 and the reception oscillation unit in the reception unit 1101 are used. Even when the phase difference of the LO signal output from 1103 fluctuates, an image generation method for stably generating a correct image of the object 1201 is provided. This provides an object detection device capable of separating the oscillating unit that generates the radio wave transmitted from the transmitting device and the oscillating unit that generates the LO signal in the receiving device.

The object detection device of the first embodiment can eliminate the wiring between the transmitting unit and the receiving unit, solve the problem of hindering the passage of pedestrians, and flexibly change the positional relationship between the transmitting device and the receiving device. It will be possible to change. In addition, the number of wiring cables for supplying radio waves can be reduced, and the problems of cost and housing size can be solved.

(Implementation 2)
[Device configuration]
The configuration of the object detection device according to the second embodiment will be described with reference to FIG.

The components of the second embodiment shown in FIG. 12 are the same as the components of the first embodiment shown in FIG. However, in the first embodiment, the oscillation unit in the transmission unit 1001 _{is separated into a plurality of transmission oscillation units 1003 1} , 1003 ₂ , 1003 _M , whereas in the second embodiment, a single transmission oscillation unit is used. It is implemented in 1003.

Further, in the first embodiment, the oscillating unit in the receiving unit 1101 is mounted by a single receiving oscillating unit 1103, whereas in the second embodiment, a plurality of receiving oscillating units 1103 ₁ , 1103 ₂ , 1103 are mounted. _It is separated into M.

That is, in the first and second embodiments of the present embodiment, the mounting by a single oscillating unit and the mounting by a plurality of oscillating units are exchanged for transmission and reception.

In the second embodiment, the radio wave supply cable shown by the double wire is used for the connection between the transmission oscillator 1003 and the transmitter 1004. On the other hand, unlike the conventional object detection device, in the second embodiment, the wiring cable for supplying radio waves is not required in the receiving unit 1101, so that the device cost can be reduced and the housing size can be reduced.

Since there is no difference other than the above between the first and second embodiments, the description of the components other than the transmission oscillation unit 1003 and the reception oscillation unit 1103 will be omitted.

[Device operation]
The operation of the device is also substantially the same in the first and second embodiments. Here, only the elements of the device operation of the second embodiment that are different from the device operation of the first embodiment will be described.

The device operation in the second embodiment is carried out according to the flow chart shown in FIG. Since the device operation according to FIG. 5 is common to the first and second embodiments, the description thereof will be omitted.

FIG. 13 shows a flow chart showing the details of step A6 in the flow chart shown in FIG. 5 among the device operations in the second embodiment. Reflecting the fact that the mounting by a single oscillator and the mounting by a plurality of oscillators are exchanged for transmission and reception in the first and second embodiments, the steps in the flow diagram 13 in the second embodiment are described in the present invention. The steps in the flow diagram 6 in the first embodiment are changed as follows. Specifically, the processing for the transmitting antenna and the processing for the receiving antenna are exchanged in the first and second embodiments.

While step B1 in the first embodiment generates an image from the IF signal by the correlation sum of the receiving antenna axes, in step B1'in the second embodiment, an image is generated from the IF signal by the correlation sum of the transmitting antenna axes. do.

While step B6 in the first embodiment calculates the transmitting antenna axis calibration term, step B6'in the second embodiment calculates the receiving antenna axis calibration term.

While step B7 in the first embodiment generates an image by the correlation sum of the transmitting antenna axes, step B7'in the second embodiment generates an image by the correlation sum of the receiving antenna axes.

FIG. 14 shows a flow chart showing the details of steps B3 and B6'in the flow chart shown in FIG. 13 among the device operations in the second embodiment. Reflecting the fact that the mounting by a single oscillator and the mounting by a plurality of oscillators are exchanged for transmission and reception in the first and second embodiments, the steps in the flow diagram 14 in the second embodiment are described in the present invention. The steps in the flow diagram 7 in the first embodiment are changed as follows. Specifically, the processing for the transmitting antenna and the processing for the receiving antenna are exchanged in the first and second embodiments.

While step C1 in the first embodiment generates an image from the IF signal by the correlation sum of the receiving antenna axes, in step C1'in the second embodiment, an image is generated from the IF signal by the correlation sum of the transmitting antenna axes. do.

While step C5 in the first embodiment calculates the correction term for the transmitting antenna shaft, step C5'in the second embodiment calculates the correction term for the receiving antenna shaft.

While step C6 in the first embodiment calculates the transmitting antenna axis calibration term, step C6'in the second embodiment calculates the receiving antenna axis calibration term.

As in the first embodiment, the phase difference between the detection signal transmitted from the transmission unit 1001 and the LO signal output from the reception oscillation unit 1103 in the reception unit 1101 fluctuates due to the device operation in the second embodiment. Even in such a case, an image generation method for stably generating a correct image of the object 1201 is provided.

(Modification 1 of the second embodiment)
FIG. 15 shows a diagram of the device configuration in the first modification of the second embodiment. In the apparatus configuration of the second embodiment shown in FIG. 12, the transmitting unit 1001 and the receiving unit 1101 are housed in different housings, but as in the modified example 1 of the second embodiment shown in FIG. The transmitting unit 1001 and the receiving unit 1101 may be housed in the same housing and used as the object detection device 1000.

In FIG. 15, the transmitting antenna 1002 connected to the transmitter 1004 and the receiving antenna 1102 connected to the receiver 1104 are separated. On the other hand, the transmitter 1004 and the receiver 1104 may be connected to the same antenna via a switch or an isolator for switching transmission / reception, and may share the same antenna for transmission / reception.

Since the device operation in the first modification of the second embodiment is the same as the device operation in the second embodiment, the description thereof will be omitted.

[Hardware configuration]
This is the same as the first embodiment.

[effect]
This is the same as the first embodiment.

(Embodiment 3 of this embodiment)
In the third embodiment, the synchronous processing described in the first and second embodiments, that is, the processing of steps A1 and A2 in FIG. 5 is more embodied. The synchronization process is a process for ensuring that the detection signal transmitted from the transmission unit 1001 and the LO signal output from the reception oscillation unit 1103 in the reception unit 1101 become signals of the same frequency at the same timing.

An example of the functional configuration of the object detection device 1000 is shown in FIGS. 1, 10, 12, or 15.

The transmission oscillation unit 1003 of the transmission unit 1001 executes the synchronization signal transmission process and the detection signal transmission process based on the control of the control unit 1005.

In the synchronous signal transmission process, the transmission oscillation unit 1003 causes the transmission antenna 1002 to transmit radio waves that carry the synchronous signal at a preset reference timing. In the detection signal transmission process, radio waves carrying the detection signal are transmitted from the transmission antenna 1002.

Hereinafter, the synchronization signal transmission process and the detection signal transmission process will be described in more detail with reference to FIG. FIG. 16 shows an example of a time change in the frequency of the radio wave transmitted by the transmission oscillation unit 1003. The horizontal axis is time and the vertical axis is frequency.

As shown in the figure, the transmission oscillation unit 1003 executes a synchronization signal transmission process for transmitting a synchronization signal before the detection signal transmission process for transmitting the detection signal. As shown in the figure, the transmission oscillation unit 1003 can execute the synchronization signal transmission process before executing the detection signal transmission process, and then repeatedly execute the synchronization signal transmission process. The transmission oscillation unit 1003 executes the detection signal transmission process during the plurality of synchronization signal transmission processes. The transmission oscillation unit 1003 may execute only the first synchronization signal transmission processing, and may not execute the subsequent synchronization signal transmission processing.

Examples of the synchronous signal include a pulse signal (unmodulated), a modulated signal, a predetermined sequence signal (PN sequence, unique word, etc.) and the like. The modulated signal is a signal whose frequency and amplitude are modulated.

The synchronization signal and the detection signal can be distinguished from each other based on at least one of the amplitude and frequency of the radio wave. For example, the synchronization signal may be a signal having a frequency outside the sweep region of the detection signal (the range from the minimum frequency to the maximum frequency taken by the detection signal). In addition, as shown in FIG. 16, when the frequency of the detection signal takes a discrete value, the synchronization signal may be a signal having a frequency within the sweep region of the detection signal and not adopted in the detection signal. In addition, the synchronization signal may have a frequency adopted in the detection signal. In this case, the synchronization signal and the detection signal can be distinguished from each other by the amplitude, the signal pattern, and the like.

Note that any of the plurality of transmitting antennas 1002 may transmit the synchronization signal. The transmission antenna 1002 that transmits the synchronization signal in advance may be fixed or may vary. In the latter case, the transmitting antenna 1002 that transmits the synchronization signal is selected from the plurality of transmitting antennas 1002 by any means.

In the detection signal transmission process, the transmission oscillation unit 1003 transmits the detection signal while changing the frequency by a predetermined algorithm. Then, the transmission oscillation unit 1003 transmits a predetermined detection signal from the transmission antenna 1002 at the transmission timing determined based on the reference timing.

The method of specifying the reference timing is a design matter, and any method can be adopted. For example, a method using the timing at which the value of the second (taking a value of 0 to 59) of the time indicated by hours, minutes, and seconds becomes "0" as a reference timing is exemplified, but the present invention is not limited to this. In the case of the example shown in FIG. 16, the time t _t0 and the time t _t1 are the reference timings. As shown in the figure, the synchronization signal is transmitted at this reference timing. The transmission timing is a timing at which a predetermined time has elapsed from the reference timing, and is, for example, the time t _1s1 or the time t _2s1 in FIG. As shown in the figure, the sweep of the frequency of the detection signal is started from a predetermined value at this transmission timing.

The synchronization signal detection unit 1109 of the reception unit 1101 detects the synchronization signal from the radio waves received by the reception antenna 1102. The synchronization signal detection unit 1109 detects the synchronization signal based on the frequency, amplitude, these patterns, and the like of the radio wave.

The reception oscillation unit 1103 generates an LO signal based on the timing at which the synchronization signal is detected. The reception oscillation unit 1103 generates a sweep signal (LO signal) whose frequency changes by the same algorithm as the generation of the detection signal.

The reception oscillation unit 1103 starts generating the LO signal from the timing when a predetermined time has elapsed from the timing when the synchronization signal is detected. That is, the sweep of the frequency of the LO signal is started from a predetermined value at the timing when a predetermined time has elapsed from the timing when the synchronization signal is detected. As described in the first embodiment, the reference timing at which the transmitting unit 1001 transmits the radio wave carrying the synchronization signal and the timing at which the receiving unit 1101 detects the synchronization signal can be regarded as the same time.

If the synchronization signal is successfully detected, the receiving unit 1101 may further have an acknowledgment means for transmitting an acknowledgment signal to that effect to the transmitting unit 1001. In this case, the receiving unit 1101 includes a transmitting antenna, and the transmitting unit 1001 includes a receiving antenna.

Next, an example of the flow of the first synchronization processing of the object detection device 1000 will be described with reference to the sequence diagram of FIG.

First, the transmission unit 1001 executes the initialization process immediately after the startup or in response to the initialization instruction input from the user. In the initialization process, the transmission unit 1001 sets the reference timing by any means (S10). The reference timing is exemplified, but is not limited to, for example, the timing when the value of the second (taking a value of 0 to 59) of the time indicated by the hour, minute, and second becomes "0".

After the initialization process, the transmission unit 1001 performs the initial synchronization process. The initial synchronization process is the first synchronization process performed after the initialization process.

In the initial synchronization process, when the reference timing set in the initialization process arrives, the transmission unit 1001 generates a synchronization signal and transmits radio waves that carry the synchronization signal (S11, S12).

When the receiving unit 1101 receives the radio wave, it demodulates the radio wave and detects the synchronization signal (S13). When the synchronization signal is successfully detected, the receiving unit 1101 extracts and sets the timing at which the synchronization signal is detected as the reference timing (S14). Then, the receiving unit 1101 generates an affirmative signal (ACK) (S15), and transmits the radio wave carrying the affirmative signal toward the transmitting unit 1001 (S16).

When the transmission unit 1001 receives the radio wave, it demodulates the radio wave and detects an affirmative signal. Then, it is determined that the initial synchronization process is completed in response to the reception of the affirmative signal (S17).

In the sequence diagram of FIG. 18, another example of the flow of the synchronization processing of the object detection device 1000 will be described. The synchronization process differs from the example shown in the sequence diagram of FIG. 17 in that no affirmative signal is generated and transmitted.

Next, an example of the flow of the image generation processing performed after the initial synchronization processing will be described with reference to the sequence diagram of FIG.

The transmission unit 1001 generates a detection signal based on the reference timing set in the initialization process, and transmits a radio wave carrying the detection signal (S30, S32). Specifically, the transmission unit 1001 generates a sweep signal (detection signal) whose frequency changes by a predetermined algorithm, and transmits a radio wave carrying the detection signal. Then, the transmission unit 1001 generates a predetermined detection signal at a timing when a predetermined time has elapsed from the reference timing. The predetermined detection signal is a detection signal having a predetermined frequency, and is, for example, a signal having a frequency initially set in a sweep signal (detection signal) whose frequency changes by a predetermined algorithm.

The receiving unit 1101 generates an LO signal based on the reference timing extracted in the initial synchronization process (S31). Specifically, the receiving unit 1101 generates a sweep signal (LO signal) whose frequency changes by a predetermined algorithm. The algorithm for generating the detection signal and the algorithm for generating the LO signal are the same. Then, the receiving unit 1101 generates a predetermined LO signal at the timing when a predetermined time has elapsed from the reference timing. The predetermined LO signal is an LO signal having a predetermined frequency, and is, for example, a signal having a frequency initially set in a sweep signal (LO signal) whose frequency changes by a predetermined algorithm.

Then, when the receiving unit 1101 receives the radio wave transmitted from the transmitting unit 1001, the receiving unit 1101 demodulates the radio wave and detects the detection signal (S33). Then, the receiving unit 1101 generates an IF signal based on the detection signal and the LO signal (S34), and generates an image based on the IF signal (S35). The details of these processes are as described in the first and second embodiments.

In the image generation process, the transmission unit 1001 and the reception unit 1101 repeat the process.

Next, in the sequence diagrams of FIGS. 20 and 21, an example of the flow of the second and subsequent synchronization processes of the object detection device 1000 will be described. This is a process when the object detection device 1000 repeatedly performs the synchronization process.

When the timing for executing the second and subsequent synchronization processes arrives, the object detection device 1000 performs the synchronization holding process shown in the figure. The timing for executing the second and subsequent synchronization processes may be the timing at which a predetermined time has elapsed from the timing at which the previous synchronization process was executed, or may be other.

The content of the synchronization retention process is the same as the initial synchronization process described using the sequence diagrams of FIGS. 17 and 18.

Other configurations of the object detection device 1000 of the third embodiment are the same as those of the first and second embodiments.

According to the object detection device 1000 of the third embodiment, the same effects as those of the first and second embodiments are realized.

(Implementation 4)
In the fourth embodiment, the synchronization process described in the third embodiment is partially modified. Specifically, in the fourth embodiment, as shown in FIG. 22, the transmission unit 1001 sequentially transmits a plurality of synchronization signals at predetermined time intervals in each synchronization processing (synchronization signal transmission processing each time). Can be sent. For example, the transmission unit 1001 may sequentially transmit a predetermined number of synchronization signals, or may repeatedly transmit synchronization signals until a positive signal is received from the reception unit 1101.

With this configuration, the receiving unit 1101 can detect the synchronization signal in each synchronization process and increase the probability that the synchronization process will succeed.

However, in this configuration, since the transmission timings of the plurality of synchronization signals are different from each other, it is specified which synchronization signal among the plurality of synchronization signals is detected by the receiving unit 1101, and the reference timing is determined based on the result. Adjustment processing is required. Therefore, the object detection device 100 of the fourth embodiment has a function of executing the following processes 1 or 2.

"Processing example 1"
When any one of the plurality of synchronization signals is successfully detected, the receiving unit 1101 sets the timing at which the synchronization signal is detected as the reference timing. Further, the receiving unit 1101 transmits a radio wave carrying a positive signal indicating that to that effect to the transmitting unit 1001 at the timing when the detection is successful.

The transmission unit 1001 corrects the set reference timing based on the reception timing of the affirmative signal.

First, when the transmission unit 1001 receives the affirmative signal, it specifies which of the plurality of synchronization signals is detected based on the reception timing of the affirmative signal. For example, the transmission unit 1001 may determine that the synchronization signal transmitted immediately before the reception timing of the affirmative signal has been detected by the reception unit 1101. In this case, for example, the transmission interval of the plurality of synchronization signals is set to be longer than the time required from the transmission of the synchronization signal to the reception of the affirmative signal corresponding to the detection of the synchronization signal.

Then, the transmission unit 1001 corrects the set reference timing based on the timing at which the specified synchronization signal is transmitted. Initially, the timing at which the first synchronization signal is transmitted is the reference timing. The synchronization signal transmitted thereafter is transmitted after a predetermined time has elapsed from the reference timing.

When the first synchronization signal is detected by the receiving unit 1101 and the corresponding affirmative signal is received, the reference timing is not changed and remains as it is. However, when the second and subsequent synchronization signals are detected by the receiving unit 1101 and the corresponding affirmative signal is received, the transmitting unit 1001 resets the reference timing. For example, when the time difference between the timing at which the first synchronization signal is transmitted and the timing at which the detected synchronization signal is transmitted is T seconds, the transmission unit 1001 sets a new reference timing after T seconds of the set reference timing. Set as.

The receiving unit 1101 sets the timing at which the synchronization signal is detected as the reference timing. By modifying the reference timing set by the transmission unit 1001 as described above, the deviation between the reference timing set by the reception unit 1101 and the reference timing set by the transmission unit 1001 is eliminated, and these timings are mutually aligned. Match.

"Processing example 2"
The plurality of synchronization signals transmitted in each synchronization signal transmission process can be distinguished from each other based on at least one of the amplitude and frequency of the radio wave. For example, it may be possible to identify the number of the transmitted synchronization signal.

When the receiving unit 1101 succeeds in detecting any one of the plurality of synchronized signals, the receiving unit 1101 specifies which of the plurality of synchronized signals is detected based on at least one of the amplitude and frequency of the radio wave. Then, the receiving unit 1101 sets the timing at which a predetermined time s has elapsed from the timing at which the synchronization signal is received as the reference timing, and generates the LO signal based on the reference timing.

The predetermined time s is the time difference between the timing at which the first synchronization signal is transmitted and the timing at which the detected synchronization signal is transmitted, and varies depending on which synchronization signal is detected. The receiving unit 1101 stores in advance information indicating the correspondence relationship between each of the plurality of synchronization signals transmitted in each synchronization signal transmission process and the predetermined time s. Then, the receiving unit 1101 refers to the information and specifies a predetermined time s corresponding to the detected synchronization signal.

Other configurations of the object detection device 1000 of the fourth embodiment are the same as those of the first to third embodiments.

According to the object detection device 1000 of the fourth embodiment, the same effects as those of the first to third embodiments are realized. Further, by sequentially transmitting a plurality of synchronization signals in each synchronization process, the receiving unit 1101 can detect the synchronization signal and increase the probability that the synchronization process will succeed.

However, in this configuration, since the transmission timings of the plurality of synchronization signals are different from each other, it is specified which synchronization signal among the plurality of synchronization signals is detected by the receiving unit 1101, and the reference timing is determined based on the result. Adjustment processing is required. If this process is not performed, the generated image will be deteriorated. The object detection device 1000 of the fourth embodiment can alleviate the problem of image deterioration by executing the above processing example 1 or 2.

(Implementation 5)
When the reception unit 1101 of the fifth embodiment fails to detect the synchronization signal in a certain synchronization process, the reception unit 1101 stores the detection signal detected from the radio waves received thereafter in the storage means in the own device. Keep it. Then, when the synchronization signal is successfully detected in the subsequent synchronization processing, an IF signal is generated based on the LO signal generated based on the timing at which the synchronization signal is received and the detection signal stored before that. An image is generated based on the IF signal.

Here, an example of a process for detecting that the detection of the synchronization signal has failed will be described. As described in the third embodiment, the object detection device 1000 performs the initial synchronization process before executing the process of transmitting and receiving the detection signal to generate an image. Therefore, if the detection signal is detected without the synchronization signal being detected, the receiving unit 1101 can determine that the detection of the synchronization signal in the initial synchronization processing has failed. Then, the receiving unit 1101 continues to store the received detection signal in the storage means until the synchronization processing is successful.

Further, the receiving unit 1101 may hold information indicating the timing at which the second and subsequent synchronization processes are executed. The timing at which the second and subsequent synchronization processes are executed is indicated by, for example, the elapsed time from the timing at which the previous synchronization process was executed. The receiving unit 1101 specifies the timing of the next synchronization processing based on the information and the timing of the synchronization processing performed last time. Then, if the synchronization signal is not detected even after a predetermined time has elapsed from the timing of the next synchronization processing, the receiving unit 1101 can determine that the synchronization signal detection has failed.

Other configurations of the object detection device 1000 of the fifth embodiment are the same as those of the first to fourth embodiments.

According to the object detection device 1000 of the fifth embodiment, the same effects as those of the first to fourth embodiments are realized. Further, according to the object detection device 1000 of the fifth embodiment, when the synchronization processing of a certain time fails, the detection signal received after that is stored, and the reference timing extracted by the subsequent successful synchronization processing is stored. It is possible to generate an image by processing the detection signal stored based on the above. Therefore, if any of the plurality of synchronization processes is successful, the detection signals transmitted and received before and after that can be appropriately processed, and an image with less deterioration can be generated.

(Implementation 6)
The receiving unit 1101 of the sixth embodiment receives radio waves by a plurality of receiving antennas 1102. Then, when the synchronization signal is detected from the radio waves received by each of the plurality of receiving antennas 1101, the receiving unit 1101 selects one synchronization signal satisfying a predetermined condition, and based on the timing at which the selected synchronization signal is received. Generate an LO signal. The predetermined condition is, for example, "the earliest received synchronization signal".

Other configurations of the object detection device 1000 of the sixth embodiment are the same as those of the first to fifth embodiments.

According to the object detection device 1000 of the fifth embodiment, the same effects as those of the first to fifth embodiments are realized. Further, according to the object detection device 1000 of the sixth embodiment, an appropriate one is selected from the synchronization signals detected from the radio waves received by each of the plurality of receiving antennas 1102, and the LO signal is generated. Can be used for. The predetermined condition is, for example, "the earliest received synchronization signal". In this case, the synchronization process can be performed based on the synchronization signal directly delivered from the transmission unit 1001 to the reception unit 1101 without being reflected by another object. As a result, the accuracy of synchronization processing is improved.

The configuration of a preferred embodiment of the present invention has been described above. However, the contents disclosed in the above-mentioned patent documents and the like can be incorporated into the present invention by citation. Within the framework of the entire disclosure (including the scope of claims) of the present invention, it is possible to change or adjust the embodiment based on the basic technical idea. In addition, various combinations or selections of various disclosed elements are possible within the scope of the claims of the present invention. That is, it goes without saying that the present invention includes various modifications and modifications that can be made by those skilled in the art in accordance with the entire disclosure including the scope of claims and the technical idea.

Some or all of the above embodiments may also be described, but not limited to:
1. 1. It is an object detection device for detecting objects by radio waves.
It is equipped with a transmitting means and a receiving means.
The transmission means is
A transmitting antenna that transmits radio waves, and
The transmission antenna transmits a radio wave that carries a predetermined detection signal at a synchronization signal transmission process that transmits a radio wave that carries a synchronization signal at a preset reference timing from the transmission antenna and a transmission timing that is determined based on the reference timing. Transmission oscillation means that executes detection signal transmission processing to be transmitted from
Have,
The receiving means
The receiving antenna that receives radio waves and
A synchronization signal detection means for detecting the synchronization signal from the radio waves received by the reception antenna, and
A receive oscillation means that generates a receive local oscillation signal based on the timing at which the synchronization signal is detected, and a receive oscillation means.
A receiver that generates an intermediate frequency signal based on the detected signal detected from the radio waves received by the receiving antenna and the received local oscillation signal.
An arithmetic means for generating an image based on the intermediate frequency signal, and
Object detection device with.
2. 2. The object detection device according to 1, wherein the synchronization signal and the detection signal can be distinguished from each other based on at least one of the amplitude and frequency of radio waves.
3. 3. The object detection device according to 1 or 2, wherein the receiving means further includes an acknowledgment means for transmitting an acknowledgment signal indicating the synchronization signal to the transmitting means when the synchronization signal is successfully detected.
4. The object detection device according to any one of 1 to 3, wherein the transmission oscillation means repeatedly performs the synchronization signal transmission process.
5. The receiving means
If the detection of the synchronization signal fails, the detection signal detected from the radio waves received by the receiving antenna after that is stored.
After that, when the synchronization signal is successfully detected, the intermediate frequency signal is generated based on the received local oscillation signal generated based on the timing at which the synchronization signal is received and the stored detection signal. 4. The object detection device according to 4, which generates an image based on the intermediate frequency signal.
6. The transmitting means sequentially transmits a plurality of the synchronized signals in each of the synchronized signal transmission processes.
When the receiving means succeeds in detecting any one of the plurality of synchronization signals, the receiving means transmits an affirmative signal indicating that fact to the transmitting means at the timing when the detection is successful.
The object detection device according to any one of 1 to 5, wherein the transmission means modifies the reference timing set based on the reception timing of the affirmative signal.
7. The transmitting means sequentially transmits a plurality of the synchronized signals in each of the synchronized signal transmission processes, and the plurality of synchronized signals carried by radio waves can be distinguished from each other based on at least one of the amplitude and frequency of the radio waves. And
When the receiving means succeeds in detecting any one of the plurality of synchronization signals, the receiving means identifies which of the plurality of synchronization signals is detected based on at least one of the amplitude and frequency of the radio wave, and the above-mentioned. The object detection device according to any one of 1 to 5, which generates the received local oscillation signal based on the timing at which the time corresponding to the synchronization signal specified from the timing at which the synchronization signal is received has elapsed.
8. The receiving means
Radio waves are received by the multiple receiving antennas,
When the synchronization signal is detected from the radio waves received by each of the plurality of receiving antennas, one synchronization signal satisfying a predetermined condition is selected, and the reception local area is based on the timing at which the selected synchronization signal is received. The object detection device according to any one of 1 to 7, which generates an oscillation signal.
9. 8. The object detection device according to 8, wherein the predetermined condition is the synchronization signal received earliest.
10. It is an object detection method executed by an object detection device that has a transmission means and a reception means and is used to detect an object by radio waves.
The transmission means is
Synchronous signal transmission processing to transmit radio waves that carry a synchronization signal from a transmission antenna at a preset reference timing, and radio waves that carry a predetermined detection signal from the transmission antenna at a transmission timing determined based on the reference timing. Executes the detection signal transmission process to be transmitted,
The receiving means
The synchronization signal is detected from the radio waves received by the receiving antenna, and the synchronization signal is detected.
A received local oscillation signal is generated based on the timing at which the synchronization signal is detected.
An intermediate frequency signal is generated based on the detection signal detected from the radio waves received by the reception antenna and the reception local oscillation signal.
An object detection method that generates an image based on the intermediate frequency signal.

110 computer 111 CPU
112 Main memory 113 Storage device 114 Input interface 115 Display controller 116 Data reader / writer 117 Communication interface 118 Input device 119 Display device 120 Recording medium 121 Bus 1000 Object detection device 1001 Transmitter 1002 Transmitter antenna 1003 Transmitter oscillator 1004 Transmitter 1005, 1110 Control unit 1101 Receive unit 1102 Receive antenna 1103 Receive oscillation unit 1104 Receiver 1105 Mixer 1106 Data transfer unit 1107 Calculation unit 1109 Synchronous signal detection unit 1201 Object 1301 Detection signal frequency 1302 LO signal frequency

Claims (10)

1. It is an object detection device for detecting objects by radio waves.
   It is equipped with a transmitting means and a receiving means.
   The transmission means is
   A transmitting antenna that transmits radio waves, and
   The transmission antenna transmits a radio wave that carries a predetermined detection signal at a synchronization signal transmission process that transmits a radio wave that carries a synchronization signal at a preset reference timing from the transmission antenna and a transmission timing that is determined based on the reference timing. Transmission oscillation means that executes detection signal transmission processing to be transmitted from
   Have,
   The receiving means
   The receiving antenna that receives radio waves and
   A synchronization signal detection means for detecting the synchronization signal from the radio waves received by the reception antenna, and
   A receive oscillation means that generates a receive local oscillation signal based on the timing at which the synchronization signal is detected, and a receive oscillation means.
   A receiver that generates an intermediate frequency signal based on the detected signal detected from the radio waves received by the receiving antenna and the received local oscillation signal.
   An arithmetic means for generating an image based on the intermediate frequency signal, and
   Object detection device with.
2. The object detection device according to claim 1, wherein the synchronization signal and the detection signal can be distinguished from each other based on at least one of the amplitude and frequency of radio waves.
3. The object detection device according to claim 1 or 2, wherein the receiving means further includes an acknowledgment means for transmitting an acknowledgment signal indicating the synchronization signal to the transmitting means when the synchronization signal is successfully detected.
4. The object detection device according to any one of claims 1 to 3, wherein the transmission oscillation means repeatedly performs the synchronization signal transmission process.
5. The receiving means
   If the detection of the synchronization signal fails, the detection signal detected from the radio waves received by the receiving antenna after that is stored.
   After that, when the synchronization signal is successfully detected, the intermediate frequency signal is generated based on the received local oscillation signal generated based on the timing at which the synchronization signal is received and the stored detection signal. The object detection device according to claim 4, which generates an image based on the intermediate frequency signal.
6. The transmitting means sequentially transmits a plurality of the synchronized signals in each of the synchronized signal transmission processes.
   When the receiving means succeeds in detecting any one of the plurality of synchronization signals, the receiving means transmits an affirmative signal indicating that fact to the transmitting means at the timing when the detection is successful.
   The object detection device according to any one of claims 1 to 5, wherein the transmission means modifies the reference timing set based on the reception timing of the affirmative signal.
7. The transmitting means sequentially transmits a plurality of the synchronized signals in each of the synchronized signal transmission processes, and the plurality of synchronized signals carried by radio waves can be distinguished from each other based on at least one of the amplitude and frequency of the radio waves. And
   When the receiving means succeeds in detecting any one of the plurality of synchronization signals, the receiving means identifies which of the plurality of synchronization signals is detected based on at least one of the amplitude and frequency of the radio wave, and the above-mentioned. The object detection device according to any one of claims 1 to 5, which generates the received local oscillation signal based on the timing at which the time corresponding to the synchronization signal specified from the timing at which the synchronization signal is received has elapsed.
8. The receiving means
   Radio waves are received by the multiple receiving antennas,
   When the synchronization signal is detected from the radio waves received by each of the plurality of receiving antennas, one synchronization signal satisfying a predetermined condition is selected, and the reception local area is based on the timing at which the selected synchronization signal is received. The object detection device according to any one of claims 1 to 7, which generates an oscillation signal.
9. The object detection device according to claim 8, wherein the predetermined condition is the synchronization signal received earliest.
10. It is an object detection method executed by an object detection device that has a transmission means and a reception means and is used to detect an object by radio waves.
    The transmission means is
    Synchronous signal transmission processing to transmit radio waves that carry a synchronization signal from a transmission antenna at a preset reference timing, and radio waves that carry a predetermined detection signal from the transmission antenna at a transmission timing determined based on the reference timing. Executes the detection signal transmission process to be transmitted,
    The receiving means
    The synchronization signal is detected from the radio waves received by the receiving antenna, and the synchronization signal is detected.
    A received local oscillation signal is generated based on the timing at which the synchronization signal is detected.
    An intermediate frequency signal is generated based on the detection signal detected from the radio waves received by the reception antenna and the reception local oscillation signal.
    An object detection method that generates an image based on the intermediate frequency signal.

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