KR102126071B1 - Method and apparatus for detecting a target - Google Patents

Abstract

The present invention provides a target detection method using a radar. The method of detecting a target using a radar provided by the present invention comprises radiating a multiple-frequency modulation continuous wave (MFMCW) detection signal based on a frequency modulation keying (FSCW) method and a frequency shift keying (FSK) method into a detection space; Receiving a reflection signal from which the MFMCW detection signal is reflected back from the detection space; Separating the FMCW signal and the FSK signal corresponding to each of the FMCW method and the FSK method from the reflected signal; And detecting a target existing in the detection space, based on the FMCW signal and the FSK signal.

Description

Method and device for detecting target using radar {METHOD AND APPARATUS FOR DETECTING A TARGET}

The present invention relates to a method and apparatus for detecting a target using a radar, and more specifically, a multi-frequency modulation continuous wave (MFMCW) signal based on a frequency modulation continuous wave (FMCW) method and a frequency shift keying (FSK) method. It relates to a method and apparatus for detecting a target located in the detection space using.

Radar is a method of analyzing complex frequency modulation from a signal that is backscattered according to the components of an object to which the radar is reflected by transmitting a transmission waveform and receiving a signal reflected from the target. Therefore, the IF (intermediate frequency) signal varies according to the shape of the transmission waveform, and information that can be extracted from the IF signal also varies.

In general, a continuous wave (CW) that continuously transmits one frequency, a frequency shift keying (FSK) that repeatedly transmits two frequencies according to the shape of the transmission waveform, and a frequency that modulates and modulates the frequency to a triangular or ramp wave to transmit the frequency modulation continuous wave), and extractable information varies depending on the transmission waveform.

Among them, the FMCW method has an advantage in that it is possible to determine whether or not the target is present in the detection space even if the target does not move. However, since the FMCW method has a low distance resolution and the distance resolution depends on a modulation bandwidth, there is a disadvantage in that it is difficult to separate a signal when obstacles and target target distances overlap. On the other hand, since the FSK method uses the phase difference generated by different frequencies to obtain the distance, it has the advantage of enabling precise distance measurement without limitation of the distance resolution, but it has the disadvantage of not being able to know if there is no movement of the target. exist.

Accordingly, there is a need for a target detection method and apparatus using a transmission waveform of a new multiple-frequency modulation continuous wave (MFMCW) method that can utilize both the advantages of the FMCW method and the FSK method.

A related prior art is Korean Registered Patent No. 10-1199169 (Invention name: target object detection method and radar device, registration date: November 1, 2012).

The present invention can accurately detect both moving and non-moving targets using a multiple-frequency modulation continuous wave (MFMCW) signal based on a frequency modulation keying (FSMW) method and a frequency shift keying (FSK) method. It is intended to provide a method and apparatus.

In order to achieve the above object, a method of detecting a target using a radar provided by the present invention detects a multiple-frequency modulation continuous wave (MFMCW) detection signal based on a frequency modulation continuous wave (FMCW) method and a frequency shift keying (FSK) method. Emitting to the detection space; Receiving a reflection signal from which the MFMCW detection signal is reflected back from the detection space; Separating the FMCW signal and the FSK signal corresponding to each of the FMCW method and the FSK method from the reflected signal; And detecting a target existing in the detection space, based on the FMCW signal and the FSK signal.

Preferably, when the target does not exist in the detection space, emitting the MFMCW detection signal, and receiving an initial reflection signal reflected and returned from the detection space; And separating an initial FMCW signal from the initial reflection signal, and detecting the target may be further based on the initial FMCW signal.

Preferably, the step of detecting the target may include: first detecting the target using the FMCW signal and the initial FMCW signal; Secondly detecting the target using the FSK signal; And synthesizing the primary detection result and the secondary detection result, and detecting the target.

Preferably, using the FSK signal, the secondary detection of the target may include calculating a speed of the target based on a Doppler frequency of carriers having two different frequencies included in the FSK signal; Calculating a distance to the target by applying a cross-correlation technique using Fast Fourier Transform (FFT), convolution and Inverse Fast Fourier Transform (IFFT) to the FSK signal; And secondly detecting the target based on the speed of the target and the distance to the target.

Preferably, the step of secondly detecting the target using the FSK signal may be detected only when a difference between Doppler frequencies of each of the two carriers included in the FSK signal is within a predetermined threshold.

Preferably, the MFMCW detection signal is a signal modulated within a predetermined modulation bandwidth during a first time (T _fmcw ) corresponding to the FMCW method, and two during a second time (T _fsk ) corresponding to the FSK method. It may be a signal that repeatedly transmits a carrier composed of frequencies.

In addition, in order to achieve the above object, the target detection apparatus using a radar provided in the present invention includes an emitter for radiating an MFMCW detection signal based on the FMCW method and the FSK method to the detection space; A receiver configured to receive a reflection signal from which the MFMCW detection signal is reflected and returned from the detection space; A signal separation unit separating the FMCW signal and the FSK signal corresponding to each of the FMCW method and the FSK method from the reflected signal; And a detection unit detecting a target existing in the detection space based on the FMCW signal and the FSK signal.

Preferably, when the target does not exist in the detection space, the radiating unit further emits the MFMCW detection signal, and the receiving unit further receives an initial reflection signal reflected and returned from the detection space, and the signal separation Further, the initial FMCW signal is further separated from the initial reflection signal, and the detection unit may be further based on the initial FMCW signal.

Preferably, the detection unit performs the primary detection of the target using the FMCW signal and the initial FMCW signal, the secondary detection of the target using the FSK signal, the primary detection result and the 2 The target can be detected by synthesizing the results of the difference detection.

Preferably, when the detection unit secondaryly detects the target using the FSK signal, the speed of the target is calculated based on a Doppler frequency of a carrier having two different frequencies included in the FSK signal, By applying a cross-correlation technique using FFT, convolution, and IFFT to the FSK signal, the distance to the target is calculated, and based on the speed of the target and the distance to the target, the target can be secondly detected. have.

Preferably, when the detection unit secondaryly detects the target using the FSK signal, it can be detected only when a difference between Doppler frequencies of each of the two carriers included in the FSK signal is within a predetermined threshold. have.

Preferably, the MFMCW detection signal is a signal modulated within a predetermined modulation bandwidth during a first time (T _fmcw ) corresponding to the FMCW method, and two during a second time (T _fsk ) corresponding to the FSK method. It may be a signal that repeatedly transmits a carrier composed of frequencies.

A method and apparatus for detecting a target using a radar according to an embodiment of the present invention by using a multiple-frequency modulation continuous wave (MFMCW) signal based on a frequency modulation continuous wave (FMCW) method and a frequency shift keying (FSK) method, It has the effect of accurately detecting both moving and non-moving targets.

1 is a flowchart of a target detection method using a radar according to an embodiment of the present invention.
2 is a flowchart of a target detection method using an FMCW signal and an FSK signal according to an embodiment of the present invention.
3 is a flowchart of a target detection method using an FSK signal according to an embodiment of the present invention.
4 is a view showing a waveform of the MFMCW detection signal according to an embodiment of the present invention.
5 is a view for explaining a target detection process using an FSK signal according to an embodiment of the present invention.
6 is a block diagram of a target detection device using a radar according to an embodiment of the present invention.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals are used for similar components.

Terms such as first, second, A, and B may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component. The term and/or includes a combination of a plurality of related described items or any one of a plurality of related described items.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but there may be other components in between. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as “include” or “have” are intended to indicate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms, such as those defined in a commonly used dictionary, should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart of a target detection method using a radar according to an embodiment of the present invention.

In step S110, the target detection device emits a multi-frequency modulation continuous wave (MFMCW) detection signal based on a frequency modulation key (FMCW) method and a frequency shift keying (FSK) method to the detection space.

Here, the FMCW method is a method of transmitting a detection signal by modulating frequencies with a triangular wave, a sine wave, a sawtooth wave, and a square wave. The FMCW method has the advantage of being able to detect the target even when the target does not move and stops. However, since the distance resolution is low and depends on the modulation bandwidth, the signal is separated when the distance between the obstacles and the target overlaps. There are disadvantages that are difficult to bet.

Further, the FSK method is a method of alternately transmitting two frequencies. Since the FSK method calculates the distance by using the phase difference generated by different frequencies, it has an advantage that it is possible to accurately measure the distance without limitation of the distance resolution, but it is difficult to detect the target when the target does not move.

Meanwhile, the MFMCW detection signal may be a signal generated to use the advantages of the two methods by applying a mixture of the FMCW method and the FSK method.

In another embodiment, the MFMCW detection signal is a signal modulated within a predetermined modulation bandwidth during the first time (T _fmcw ) corresponding to the FMCW method, and has two frequencies during the second time (T _fsk ) corresponding to the FSK method. It may be a signal that repeatedly transmits the configured carrier.

For example, referring to FIG. 4, the MFMCW detection signal may be configured in an FMCW scheme in which the frequency increases linearly from 0 Hz to 50 MHz modulation bandwidth during the first time (T _fmcw ). In addition, during the second time (T _fsk ), it may be configured by an FSK method that alternates and repeats carriers composed of two frequencies of 40 MHz and 50 MHz.

In addition, the MFMCW detection signal may be generated such that the first time and the second time are continuously repeated as shown in FIG. 4. More specifically, the first time period (T _fmcw) for FMCW method, a second time (T _fsk) for FSK method, method FMCW for another first time period (T _fmcw), a second time (T _fsk) FSK scheme for, and For the first time (T _fmcw ) again, the FMCW method may be continuously repeated.

In step S120, the target detection device receives the reflected signal from which the MFMCW detection signal is reflected back from the detection space.

At this time, the target detection device may be equipped with an antenna suitable for receiving the reflected signal, and the fixed object (eg, wall, column, ceiling, etc.) and moving object (eg, person, vehicle) located in the detection space using the antenna , Motorcycle, etc.) to receive the reflected signal.

In step S130, the target detection device separates the FMCW signal and the FSK signal corresponding to each of the FMCW method and the FSK method from the reflected signal.

For example, the target detection device may separate the FMCW signal from the reflected signal for the first time T _fmcw and separate the FSK signal from the reflected signal for the second time T _fsk . In addition, the target detection device may separate the FMCW signal and the FSK signal by further referring to information on the modulation bandwidth of the FMCW method or the carrier frequency of the FSK method.

Finally, in step S140, the target detection device detects the target existing in the detection space based on the FMCW signal and the FSK signal.

At this time, the target detection device may detect the target in the detection space using the FMCW signal, and at the same time, the target in the detection space using the FSK signal.

In another embodiment, the target detection device may detect the target by removing noise corresponding to the background included in the FMCW signal.

To this end, the target detection device emits an MFMCW detection signal when a target does not exist in the detection space, receives an initial reflection signal that is reflected back from the detection space, and then receives an initial FMCW signal from the initial reflection signal. Can be separated. And, when detecting a target existing in the detection space, the target detection device may detect the target based on the FMCW signal and the FSK signal as well as the initial FMCW signal.

Meanwhile, a detailed method for the target detection apparatus to detect the target based on the FMCW signal and the FSK signal will be described later in detail with reference to FIG. 2.

As described above, the method and apparatus for detecting a target using a radar according to an embodiment of the present invention have an effect of accurately detecting both a moving target and a non-moving target by using an MFMCW signal based on the FMCW method and the FSK method. have.

2 is a flowchart of a target detection method using an FMCW signal and an FSK signal according to an embodiment of the present invention.

In step S210, the target detection device primarily detects the target using the FMCW signal and the initial FMCW signal.

For example, the target detection device may detect the target using a signal obtained by removing the initial FMCW signal from the FMCW signal. At this time, the target detection device can detect both a moving target and a stationary target that does not move.

More specifically, the FMCW signal can determine whether or not the target exists in the detection space even if the target does not move. However, in the FMCW signal, not only information about the target, but also information on many obstacles occurring in a special environment such as SYAN can be mixed as in Equation 1 below.

[Equation 1]

Here, f _b is the beat frequency, which is the IF signal of the target operator, N is the number of obstacles, and m _i is the magnitude of the signal according to the second obstacle.

Therefore, as shown in Equation 2, the interference signal caused by the obstacles can be removed by subtracting the result of the FFT, so that only the reflected signal of the target can be obtained. The same effect can be obtained by repeatedly subtracting one cycle from the time axis as a reference signal.

[Equation 2]

In step S220, the target detection device secondaryly detects the target using the FSK signal.

For example, the target detection device may detect a moving target from the FSK signal. In this case, a detailed method of detecting a target moving from the FSK signal by the target detection device will be described later in detail with reference to FIG. 3.

Finally, in step S230, the target detection device synthesizes the primary detection result and the secondary detection result, and detects the target.

For example, when the target detection apparatus assumes that the set of targets included in the primary detection result is A and the set of targets included in the secondary detection result is B, the targets having the same position as the elements included in B are excluded from A. You can (AB) and combine it with B to detect it as a target ((AB)∪B).

At this time, the target of the same position as the element included in A is excluded because the target can be detected with a higher resolution using the FSK signal.

3 is a flowchart of a target detection method using an FSK signal according to an embodiment of the present invention.

In step S310, the target detection device calculates the speed of the target based on the Doppler frequency of the carrier having two different frequencies included in the FSK signal.

For example, a signal reflected by transmitting two different frequency carriers has a component of the Doppler frequency corresponding to each carrier frequency, and the target detection device can calculate the speed by obtaining the Doppler frequency. At this time, since the difference between the Doppler frequencies occurring between the two carrier frequencies is very small, it is assumed that the Doppler frequencies are the same when the speeds are the same, and it is determined whether the two speed components are the same.

In addition, the target detection device determines if a velocity component is detected only at one carrier frequency or if the velocity information at two carrier frequencies are different, it is determined as a malfunction due to noise, and the velocity information can be extracted only when the two velocity components are the same. have.

와

를 곱하고 및 IFFT(Inverse Fast Fourier Transform)을 이용하여 시간축으로 도메인을 변환하는 상호상관기법을 적용하여, 목표물까지의 거리를 산출한다.In step S320, the target detection device converts the time-axis signal to the frequency axis through an FFT (Fast Fourier Transform) to the FSK signal, and then receives the conjugate signal for convolution.

Wow

The distance to the target is calculated by multiplying and applying a cross-correlation technique that transforms the domain on the time axis using IFFT (Inverse Fast Fourier Transform).

For example, the target detection device may calculate the distance component to the target using Equation (3).

[Equation 3]

Finally, in step S330, the target detection device secondaryly detects the target based on the speed of the target and the distance to the target.

At this time, the target detection device may process the signal by separating the FSK signal by the number of samples per FSK period as shown in FIG. 5 to know the location information such as the speed and distance of the target. Since the FSK method uses the phase difference of two different transmission frequency to obtain a distance, it can be said that the key to signal processing is how accurately the phase difference between the two signals can be obtained. Since the target detection device knows the switching process of two different carrier frequencies, the signal can be separated again by the number of samples per FSK period. For example, the separated four received signals (s1, s2, s3, s4) corresponding to the FSK period samples are two pairs (f1, f3), (f2, f4) having different carrier frequencies through the primary FFT. Separated by, Conjugate multiplier (f13), (f24) and cross-correlation through the second FFT to obtain two cross-correlation values.

In another embodiment, the target detection device may secondaryly detect the target only when the difference between the Doppler frequencies of the two carriers included in the FSK signal is within a predetermined threshold.

That is, if the velocity component is detected from the difference in the Doppler frequency or the velocity information in the two carrier frequencies are different from each other, the target detection apparatus may not detect the target secondaryly by determining this as a malfunction due to noise. You can. On the other hand, the target detection device can secondarily detect the target only when the difference between the two speed components is within a threshold.

6 is a block diagram of a target detection device using a radar according to an embodiment of the present invention.

Referring to FIG. 6, a target detection device 600 using a radar according to an embodiment of the present invention includes a radiating unit 610, a receiving unit 620, a signal separation unit 630, and a detection unit 640 You can.

At this time, the target detection device 600 may be mounted on a radar system for various purposes. For example, the target detection device 600 may be mounted on a radar system for detecting a person in a dangerous area such as a factory, shipyard, or construction site.

The radiator 610 radiates an MFMCW detection signal based on the FMCW method and the FSK method to the detection space.

In another embodiment, the MFMCW detection signal is a signal modulated within a predetermined modulation bandwidth during the first time (T _fmcw ) corresponding to the FMCW method, and has two frequencies during the second time (T _fsk ) corresponding to the FSK method. It may be a signal that repeatedly transmits the configured carrier.

The receiving unit 620 receives the reflected signal from which the MFMCW detection signal is reflected from the detection space and returns.

On the other hand, in FIG. 6, for convenience, the receiver 620 is indicated as receiving information (ie, a reflected signal) from the radiator 610, but in reality, the radiator 610 radiates to the detection space, and the receiver 620 is The reflection signal is received from the detection space.

The signal separation unit 630 separates the FMCW signal and the FSK signal corresponding to each of the FMCW method and the FSK method from the reflected signal.

Finally, the detector 640 detects a target existing in the detection space based on the FMCW signal and the FSK signal.

In another embodiment, when the target does not exist in the detection space, the radiator 610 further emits the MFMCW detection signal, and the receiver 620 further receives the initial reflection signal reflected and returned from the detection space, and the signal The separation unit 630 further separates the initial FMCW signal from the initial reflection signal, and the detection unit 640 may further detect the target based on the initial FMCW signal.

In another embodiment, the detector 640 primarily detects the target using the FMCW signal and the initial FMCW signal, and secondly detects the target using the FSK signal, and the primary detection result and the secondary Targets can be detected by synthesizing the detection results.

In another embodiment, when the detector 640 secondaryly detects the target using the FSK signal, the target speed is calculated based on the Doppler frequency of the carrier having two different frequencies included in the FSK signal. Then, by applying a cross-correlation technique using FFT, convolution, and IFFT to the FSK signal, the distance to the target is calculated, and the target can be secondly detected based on the speed of the target and the distance to the target.

In another embodiment, when the detector 640 secondaryly detects the target using the FSK signal, the difference between the Doppler frequencies of each of the two carriers included in the FSK signal is detected only within a predetermined threshold. can do.

Meanwhile, the above-described embodiments of the present invention can be written in a program executable on a computer and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium.

The computer-readable recording medium includes a magnetic storage medium (eg, ROM, floppy disk, hard disk, etc.), optical reading medium (eg, CD-ROM, DVD, etc.).

So far, the present invention has been focused on the preferred embodiments. Those skilled in the art to which the present invention pertains will understand that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered in terms of explanation, not limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent range should be interpreted as being included in the present invention.

Claims (12)

Radiating a multiple-frequency modulation continuous wave (MFMCW) detection signal based on a frequency modulation keying (FSMW) method and a frequency shift keying (FSK) method into a detection space;
Receiving a reflection signal from which the MFMCW detection signal is reflected back from the detection space;
Separating the FMCW signal and the FSK signal corresponding to each of the FMCW method and the FSK method from the reflected signal; And
Detecting a target existing in the detection space based on the FMCW signal and the FSK signal
And includes
The MFMCW detection signal includes the FMCW method signal for the first time and the FSK method signal for the second time, and the FMCW method signal for the first time and the FSK method signal for the second time are generated to alternately repeat. Target detection method using a radar, characterized in that. According to claim 1,
When the target does not exist in the detection space, emitting the MFMCW detection signal and receiving an initial reflection signal reflected and returned from the detection space; And
Separating an initial FMCW signal from the initial reflection signal
Further comprising,
The step of detecting the target is
Target detection method using a radar, characterized in that further based on the initial FMCW signal. According to claim 2,
The step of detecting the target is
First detecting the target using the FMCW signal and the initial FMCW signal;
Secondly detecting the target using the FSK signal; And
Synthesizing the primary detection result and the secondary detection result, and detecting the target
Target detection method using a radar, characterized in that it comprises a. According to claim 1,
The second step of detecting the target using the FSK signal is
Calculating a speed of the target based on a Doppler frequency of carriers having two different frequencies included in the FSK signal;
Calculating a distance to the target by applying a cross-correlation technique using Fast Fourier Transform (FFT), convolution and Inverse Fast Fourier Transform (IFFT) to the FSK signal; And
Secondly detecting the target based on the speed of the target and the distance to the target
Target detection method using a radar, characterized in that it comprises a. According to claim 4,
The second step of detecting the target using the FSK signal is
A method of detecting a target using a radar, characterized in that detection is performed only when a difference between Doppler frequencies of each of the two carriers included in the FSK signal is within a predetermined threshold. According to claim 1,
The MFMCW detection signal
It is a signal modulated within a predetermined modulation bandwidth during a first time (T _fmcw ) corresponding to the FMCW method, and a carrier composed of two frequencies is repeated during a second time (T _fsk ) corresponding to the FSK method. The target detection method using a radar, characterized in that the transmitted signal. An emitter for radiating an MFMCW detection signal based on the FMCW method and the FSK method to the detection space;
A receiver configured to receive a reflection signal from which the MFMCW detection signal is reflected and returned from the detection space;
A signal separation unit separating the FMCW signal and the FSK signal corresponding to each of the FMCW method and the FSK method from the reflected signal; And
Based on the FMCW signal and the FSK signal, a detection unit for detecting a target existing in the detection space
Including,
The MFMCW detection signal includes the FMCW method signal for the first time and the FSK method signal for the second time, and the FMCW method signal for the first time and the FSK method signal for the second time are generated to alternately repeat. Target detection device using a radar, characterized in that. The method of claim 7,
When the target does not exist in the detection space, the radiator further radiates the MFMCW detection signal, the receiver further receives an initial reflection signal that is reflected back from the detection space, and the signal separation unit performs the initial reflection. Further separate the initial FMCW signal from the signal,
The detection unit
Target detection device using a radar, characterized in that further based on the initial FMCW signal. The method of claim 8,
The detection unit
The primary detection of the target using the FMCW signal and the initial FMCW signal, the secondary detection of the target using the FSK signal, and the synthesis of the primary detection result and the secondary detection result, Target detection device using a radar, characterized in that for detecting the target. The method of claim 7,
When the detection unit performs the secondary detection of the target using the FSK signal,
The target speed is calculated based on the Doppler frequency of the carrier having two different frequencies included in the FSK signal,
The cross-correlation technique using FFT, convolution and IFFT is applied to the FSK signal to calculate the distance to the target,
A target detection apparatus using a radar, characterized in that the target is secondarily detected based on the speed of the target and the distance to the target. The method of claim 10,
When the detection unit performs the secondary detection of the target using the FSK signal,
Target detection device using a radar, characterized in that the detection only when the difference between the Doppler frequency of each of the two carriers included in the FSK signal is within a predetermined threshold. The method of claim 7,
The MFMCW detection signal
It is a signal modulated within a predetermined modulation bandwidth during a first time (T _fmcw ) corresponding to the FMCW method, and a carrier composed of two frequencies is repeated during a second time (T _fsk ) corresponding to the FSK method. Target detection device using a radar, characterized in that the transmitted signal.

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