Method, radar and computer-readable storage medium for detecting using frequency modulated continuous waves

Abstract

Method, radar and computer-readable storage medium for detection using frequency modulated continuous waves. The present invention provides a method for detection using frequency modulated continuous waves, comprising the following steps: emitting a detection wave to detect a target, wherein the detection wave is a nonlinear swept frequency modulation signal; receiving an echo after the detection wave is reflected on the target; obtaining an actual beat frequency signal based on the echo and the detection wave; and obtaining the distance and / or speed of the target based on the actual beat frequency signal. The present invention proposes a radar solution based on nonlinear frequency sweeping, which can complete the decoupling and separation of distance / speed information within a single cycle. The decoupling and separation of distance / speed can be completed within a single sweep frequency cycle, maintaining the detection probability of the system from being deteriorated; at the same time, the modulation form of the single sideband can enable the system to achieve a higher sensitivity.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric detection technology, and more specifically, to a method for detecting using frequency modulated continuous waves, a radar and a computer-readable storage medium. Background Art

[0002] Frequency Modulation Continuous Wave (FMCW) radar refers to a continuous wave radar whose transmission frequency is modulated by a specific signal. FMCW radar obtains the distance information of the target by comparing the difference between the frequency of the echo signal at any time and the frequency of the transmitted signal at this time. The distance is proportional to the frequency difference between the two. The radial velocity and distance of the target can be obtained by processing the measured frequency difference between the two. Compared with other types of ranging and speed measurement radars, FMCW radar has a simpler structure. It has a low required transmission power peak, is easy to modulate, has a low cost, and has simple signal processing. It is a commonly used radar solution.

[0003] In FMCW radar, a linear frequency sweep signal is generally used as the radar's transmitting signal. The distance and speed information of the detected target will cause the frequency of the final detected beat signal to change. In order to separate the distance and speed information of the detected target, multi-frequency sweep modulation or double-sideband modulation is generally used. Figure 1A The multi-sweep modulation scheme is shown, that is, the modulation signal is composed of multiple linear sweeps with different sweep rates in the time domain. Since the sweep rate affects the coefficient of change of the target distance to the beat frequency, the distance and speed information of the target can be separated. The most common method is to use a triangular wave modulation scheme with sweep rates that are opposite to each other, see Figure 1A . Figure 1B The double-sideband modulation scheme is shown, that is, the double-sideband modulation process implemented by an electro-optical modulator directly generates upper / lower sidebands with opposite sweep rates, thereby completing the separation of target distance and speed information.

[0004] For multi-sweep modulation, its time-division multiplexing nature makes the decoupling of the target completely dependent on the consistency of the target characteristics detected by each sweep signal. For the triangle wave modulation scheme, whether the rising edge and the falling edge are for the same target is a very critical premise. Even for the same target, the detection probability problem introduced by the speckle effect in coherent detection will be amplified in the multi-sweep modulation scheme: for example, when the system's detection probability for a specific target is 90%, the detection probability of the triangle wave modulation scheme will be reduced to 81% (=90%×90%), which will greatly affect the quality of the final radar point cloud.

[0005] For double-sideband modulation, a very critical indicator is the proportion of single-sideband energy in the total energy. General double-sideband modulation schemes include intensity modulators and phase modulators: intensity modulators have a higher effective energy ratio, but the modulation efficiency is very low; phase modulators have a higher modulation efficiency, but the effective energy ratio is very low. Therefore, double-sideband modulation schemes generally require the introduction of additional filtering and amplification modules after electro-optical modulation, which increases the cost and complexity of the system.

[0006] Among them, FMCW radar can be implemented by laser radar or millimeter wave radar.

[0007] The contents of the background technology section are merely the technologies known to the public and do not necessarily represent the existing technologies in the field. Summary of the invention

[0008] In view of at least one drawback of the prior art, the present invention provides a method for detecting using a frequency modulated continuous wave, comprising the following steps:

[0009] Transmitting a detection wave to detect a target object, wherein the detection wave is a nonlinear swept frequency modulation signal;

[0010] Receiving an echo after the detection wave is reflected on the target object;

[0011] Obtaining an actual beat signal according to the echo and the detection wave; and

[0012] The distance and / or speed of the target object is obtained according to the actual beat frequency signal.

[0013] According to one aspect of the present invention, the method further comprises:

[0014] acquiring a plurality of pre-stored beat frequency signals corresponding to different distances and / or speeds;

[0015] The step of obtaining the distance and / or speed of the target object according to the actual beat frequency signal further comprises:

[0016] matching the phase function of the actual beat frequency signal with the phase functions of the plurality of pre-stored beat frequency signals respectively;

[0017] selecting a pre-stored beat frequency signal that has the highest degree of matching with the actual beat frequency signal;

[0018] The distance and / or speed corresponding to the pre-stored beat signal with the highest matching degree is used as the distance and / or speed of the target object.

[0019] According to one aspect of the present invention, the plurality of pre-stored beat frequency signals correspond to different distances respectively, and the step of selecting a pre-stored beat frequency signal that has the highest matching degree with the actual beat frequency signal further comprises:

[0020] Selecting a pre-stored beat signal having a waveform shape that best matches the actual beat signal;

[0021] Using the distance measurement information corresponding to the pre-stored beat frequency signal with the highest matching degree as the distance of the target object;

[0022] Wherein, the step of obtaining the distance and / or speed of the target object according to the actual beat frequency signal further includes:

[0023] The speed of the target object is determined according to the frequency difference between the actual beat frequency signal and the pre-stored beat frequency signal with the highest matching degree.

[0024] According to one aspect of the present invention, the plurality of pre-stored beat frequency signals correspond to different combinations of distances and speeds, respectively, and the step of selecting a pre-stored beat frequency signal having the highest matching degree with the actual beat frequency signal further comprises:

[0025] Selecting a pre-stored beat signal that has the highest degree of matching of the waveform shape and position of the actual beat signal;

[0026] The distance and speed corresponding to the pre-stored beat signal with the highest matching degree are used as the distance and speed of the target object.

[0027] According to one aspect of the present invention, the nonlinear swept frequency modulation signal is a quadratic curve function.

[0028] According to one aspect of the present invention, the step of obtaining the distance and speed of the target object according to the actual beat frequency signal further includes:

[0029] Obtaining instantaneous phase information of the actual beat frequency signal;

[0030] Subtracting the instantaneous phase information of the actual beat frequency signal from the phase information of its delayed signal;

[0031] Based on the slope of the phase difference between the two, obtaining the distance information of the target object;

[0032] The speed of the target object is obtained according to the distance information and the instantaneous phase information of the actual beat frequency signal.

[0033] The present invention also provides a radar, comprising:

[0034] A transmitting unit, wherein the transmitting unit is configured to transmit a detection wave to detect a target object, wherein the detection wave is a nonlinear swept frequency modulation signal;

[0035] a receiving unit, configured to receive an echo reflected by the detection wave on the target object and output an echo signal;

[0036] A control unit is coupled to the laser and the detection unit and receives the echo signal, and the control unit is configured to obtain an actual beat signal based on the echo and the detection wave, and obtain the distance and / or speed of the target object based on the actual beat signal.

[0037] According to one aspect of the present invention, the control unit pre-stores a plurality of pre-stored beat frequency signals corresponding to different distances and / or speeds;

[0038] Wherein the control unit is configured as:

[0039] matching the phase function of the actual beat frequency signal with the phase functions of the plurality of pre-stored beat frequency signals respectively;

[0040] selecting a pre-stored beat frequency signal that has the highest degree of matching with the actual beat frequency signal;

[0041] The distance and / or speed corresponding to the pre-stored beat signal with the highest matching degree is used as the distance and / or speed of the target object.

[0042] According to one aspect of the present invention, the plurality of pre-stored beat frequency signals correspond to different distances respectively, wherein the control unit is configured to:

[0043] Selecting a pre-stored beat signal having a waveform shape that best matches the actual beat signal;

[0044] Using the distance measurement information corresponding to the pre-stored beat frequency signal with the highest matching degree as the distance of the target object;

[0045] The speed of the target object is determined according to the frequency difference between the actual beat frequency signal and the pre-stored beat frequency signal with the highest matching degree.

[0046] According to one aspect of the present invention, the plurality of pre-stored beat frequency signals correspond to different combinations of distances and speeds, respectively.

[0047] Wherein the control unit is configured as:

[0048] Selecting a pre-stored beat signal that has the highest degree of matching of the waveform shape and position of the actual beat signal;

[0049] The distance and speed corresponding to the pre-stored beat signal with the highest matching degree are used as the distance and speed of the target object.

[0050] According to one aspect of the present invention, the nonlinear swept frequency modulation signal is a quadratic curve function.

[0051] According to one aspect of the present invention, the control unit is configured to:

[0052] Obtaining instantaneous phase information of the actual beat frequency signal;

[0053] Subtracting the instantaneous phase information of the actual beat frequency signal from the phase information of its delayed signal;

[0054] Based on the slope of the phase difference between the two, obtaining the distance information of the target object;

[0055] The speed of the target object is obtained according to the distance information and the instantaneous phase information of the actual beat frequency signal.

[0056] The present invention also provides a computer-readable storage medium on which computer program codes executable by a processor are stored. When the codes are executed by one or more processors, the processors are caused to execute the method as described above.

[0057] The present invention mainly aims at the problem of distance / speed information coupling in FMCW radar, and proposes a radar solution based on nonlinear frequency sweeping, which can complete the decoupling and separation of distance / speed information in a single cycle. The nonlinear frequency sweeping signal used in the embodiment of the present invention is completely independent of the "perception ability" of the target distance and speed information: that is, for any state of the detected target, the phase information of the beat signal caused by it is uniquely determined. Utilizing this feature, the decoupling and separation of the target distance and speed can be completed without using time division multiplexing and double sideband modulation. And the subsequent signal processing process. The advantage of the present invention is that it can complete the decoupling and separation of distance / speed in a single frequency sweeping cycle, maintaining the detection probability of the system from being deteriorated; at the same time, the modulation form of the single sideband can enable the system to achieve a higher sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0059] Figure 1A The scheme of multi-sweep frequency modulation in FMCW radar is shown;

[0060] Figure 1B The scheme of double sideband modulation in FMCW radar is shown;

[0061] Figure 2 A method for detecting using a frequency modulated continuous wave according to an embodiment of the present invention is shown;

[0062] Figure 3 The time domain waveform of a nonlinear swept frequency modulation signal is given;

[0063] Figure 4A ,4B 4C and 4C respectively show the lateral offset of the echo signal relative to the reference signal and the corresponding waveform of the beat frequency signal at three target distances;

[0064] Figure 5A , 5B 5C and 5C respectively show the longitudinal offset of the echo signal relative to the reference signal and the corresponding waveform of the beat frequency signal at three target speeds;

[0065] Figure 6 A two-dimensional surface is shown that characterizes the matching degree between the phase function of the beat signal and the phase function of the echo;

[0066] Figure 7 A schematic diagram of a laser radar according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0067] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0068] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0069] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is lower in level than the second feature.

[0071] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0072] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0073] The present invention mainly relates to a modulation signal and a demodulation method thereof in an FMCW radar system. Figure 2 A method 100 for detecting using a frequency modulated continuous wave according to an embodiment of the present invention is shown and will be described in detail below with reference to the accompanying drawings.

[0074] In step S101, the radar transmits a detection wave to detect a target object, wherein the detection wave is a nonlinear swept frequency modulation signal.

[0075] The detection wave may be a nonlinear frequency sweep modulation signal of any order, such as a quadratic function or a cubic function, or even a higher-order function.

[0076] In the scheme of the present invention, by transmitting the detection wave of the nonlinear swept frequency modulation signal, the distance and speed of the target object can be directly decoupled without adopting methods such as time division multiplexing or double-sideband modulation, thereby avoiding the problems caused by such methods, such as the problem of reduced detection probability or the problem of high system complexity. In addition to being used for the detection of the target object, the nonlinear swept frequency modulation signal will also be used as a reference signal when the distance and speed of the target object are calculated later. In addition, in the context of the present invention, the distance of the target object can be characterized by the actual distance, and can also be characterized by the flight time TOF of the detection wave (flight time (d) * speed of light c / 2 = target distance z). For the sake of unity, the actual distance of the target object will be used for illustration.

[0077] In step S102, the radar receives the echo after the detection wave is reflected on the target object.

[0078] The instantaneous frequency of the nonlinear swept frequency modulation signal of the detection wave is expressed by f0(t), Figure 3 An example of the time domain waveform of a nonlinear swept frequency modulation signal is given. The detection wave is diffusely reflected on the target, and the radar receives the echo after diffuse reflection for signal processing. The delay component and Doppler frequency shift component of the echo are d and f respectively. d , where d corresponds to the distance information z of the target (also reflected as the flight time of the detection wave), f d Corresponding to the velocity information of the target, the instantaneous frequency of the echo is f0(td)+f d .

[0079] In step S103, an actual beat signal is obtained according to the echo wave and the detection wave.

[0080] The frequency of the beat signal is the difference between the detection wave signal and the echo signal, that is, f0(t)-f0(td)-f d , the instantaneous phase characteristic of the beat frequency signal can be expressed as the following formula (1):

[0081]

[0082] In step S104, the distance and / or speed of the target object is obtained according to the actual beat frequency signal.

[0083] Let the instantaneous phase of the reference signal be (i.e. the integral of f0(t)), the above formula can be written as:

[0084]

[0085] When the modulation signal of the detection wave adopts linear frequency sweep, is a quadratic function of t, the term is a linear function of t, and the term f d t is also a linear function of t, so the delay d of the target position is related to the speed f d right The effects cannot be decoupled.

[0086] According to the present invention, when the modulation signal of the detection wave adopts nonlinear frequency sweep, the term is not a simple linear function of t, but the term f d t is still a linear function of t, so the target position z and velocity v (and Doppler frequency shift f d Corresponding) The effect is not the same, it has enough information to separate the two.

[0087] The inventors have found that the position of the target object (the distance relative to the position where the detection wave is emitted) determines the waveform of the actual beat frequency signal. Figure 4A , 4B As shown in Figure 4C, it can be seen that for different target distances, the waveform of the actual beat signal is also different. In addition, the position of the target causes the delay of the echo signal, which causes the instantaneous frequency curve of the echo signal to move horizontally (in time) relative to the instantaneous frequency curve of the reference signal. When the distance of the target is different, the lateral displacement caused is different, and the shape of the coherent beat result with the reference signal (as shown by the red line in the figure) is also different. Figure 4A , 4B In 4C, assuming that the speed (relative speed) of the target is the same, the lateral displacement of the instantaneous frequency curve of the echo signal relative to the instantaneous frequency curve of the reference signal at three distances from the target is shown. Figure 4A In , the target is closest, so the lateral offset of the echo signal relative to the reference signal is the smallest; in Figure 4C In , the target is farthest away, so the lateral offset of the echo signal relative to the reference signal is the largest; in Figure 4B The situation is Figure 4A and 4C between.

[0088] The shape of the beat signal is obtained based on the phase subtraction between the reference signal and the echo signal. Therefore, for a nonlinear swept frequency signal, when the relative offset positions of the two are different, the shape of the beat signal will be different.

[0089] A pre-stored signal with the same shape as the current beat signal is found based on the shape of the current beat signal, and the distance of the current beat signal is determined based on the distance information of the pre-stored signal.

[0090] In addition, the speed of the target (relative to the speed of the detection wave transmitting device) will cause the Doppler frequency shift of the echo signal, so that the instantaneous frequency curve of the echo signal moves longitudinally (in frequency) relative to the instantaneous frequency curve of the reference signal. The different speeds of the target will cause different longitudinal displacements, but the shape of the coherent beat frequency result with the reference signal will not be affected, and it will just move longitudinally with the target. Figure 5A , 5B As shown in FIG5C , it is assumed that the distance to the target is the same, but the speed of the target is different. Since the distance to the target is the same, the waveform of the coherent beat signal between the echo signal and the reference signal is the same; however, since the speed of the target is different, the beat signal moves up and down in the vertical axis direction.

[0091] Through the above analysis, it can be known that the beat signal actually contains two-dimensional information of the distance and speed of the target object, wherein the waveform shape of the beat signal can characterize the distance of the target object, and the offset of the beat signal along the longitudinal direction (frequency direction) can characterize the speed of the target object. After the actual beat signal is obtained in step S103, the distance and / or speed of the target object can be further obtained according to the actual beat signal. Therefore, through the present invention, the distance of the target object can be uniquely determined based on the "shape" of the instantaneous frequency of the beat signal, and the speed of the target object can be uniquely determined by the "height" of the instantaneous frequency of the beat signal.

[0092] In the method 100, it is preferred to further include: obtaining a plurality of pre-stored beat signals corresponding to different distances and / or speeds. The pre-stored beat signals may be obtained through multiple experiments or computer simulations, and each beat signal corresponds to a different distance, a different speed, or a different combination of distance and speed of the target object, that is, each beat signal may have distance information and / or speed information.

[0093] On this basis, after obtaining the actual beat signal, the phase function of the actual beat signal can be matched with the phase functions of the multiple pre-stored beat signals respectively, and the pre-stored beat signal with the highest degree of matching with the actual beat signal is selected, and then the distance and / or speed corresponding to the pre-stored beat signal with the highest degree of matching is used as the distance and / or speed of the target object.

[0094] For example, the multiple pre-stored beat signals correspond to different combinations of distances and speeds, so the pre-stored beat signal with the highest degree of match with the waveform shape and position of the actual beat signal is selected; the distance and speed corresponding to the pre-stored beat signal with the highest degree of match are used as the distance and speed of the target object.

[0095] Different target distances (corresponding to different delays d) and speeds (corresponding to different Doppler shifts f) can be obtained in advance through experiments or computer simulations. d ) The phase of the beat frequency signal As the pre-stored beat signal, the phase of each pre-stored beat signal is then subtracted from the instantaneous phase of the beat signal of the target echo signal actually acquired, and accumulated in the time domain to obtain the corresponding cumulative information characterizing the degree of matching between the phase function of the beat signal and the echo phase function.

[0096] refer to Figure 6 , Figure 6 A two-dimensional surface diagram illustrating the matching degree between an echo signal and each pre-stored signal.

[0097] The echo signal is defined as r(t), then it is related to any pre-stored signal s(t,f d ,d)(delay is d, Doppler frequency shift is f d )’s matching function M(f d ,d) can be expressed as:

[0098]

[0099] Figure 6 The two-dimensional surface shown is the matching function M(f d ,d) Graphical representation. The value of the matching function M is used to indicate the matching degree between the echo signal and the pre-stored signal. The larger the value of the matching function M, the higher the matching degree.

[0100] For any nonlinear swept frequency signal, the matching function M has only a single peak. Figure 6 As shown, the matching function M at point f d ',d'), which means that the echo signal r(t) and the pre-stored signal s(t,f d ',d') is the best match, then d' and f can be used d 'As the delay and Doppler frequency shift of the echo signal, the distance and speed information of the target can be determined.

[0101] The above algorithm is a general algorithm and can demodulate any form of nonlinear swept frequency signals, such as quadratic, cubic or even higher order nonlinear swept frequency signals.

[0102] Alternatively, each pre-stored beat signal may correspond to a different distance, and then the pre-stored beat signal with the highest matching degree with the waveform shape of the actual beat signal is selected, and then the distance information corresponding to the pre-stored beat signal with the highest matching degree is used as the distance of the target, that is, the distance information of the target is obtained. Then, the speed of the target is determined based on the frequency difference between the actual beat signal and the pre-stored beat signal with the highest matching degree.

[0103] In addition, each pre-stored beat signal may correspond to a different speed, then according to the height of the beat signal in the longitudinal direction, the pre-stored beat signal with the highest degree of height matching is selected, and the speed information corresponding to the pre-stored beat signal with the highest degree of matching is used as the speed of the target object, that is, the speed information of the target object is obtained. Then, based on the speed information of the target object, the distance of the target object is determined.

[0104] Preferably, according to a preferred embodiment of the present invention, when the detection wave adopts a nonlinear frequency sweep modulation signal of a quadratic function, the distance and / or speed of the target object can be quickly acquired by:

[0105] Obtaining instantaneous phase information of the actual beat frequency signal;

[0106] Subtracting the instantaneous phase information of the actual beat frequency signal from the phase information of its delayed signal;

[0107] Based on the slope of the phase difference between the two, obtaining the distance information of the target object;

[0108] The speed of the target object is obtained according to the distance information and the instantaneous phase information of the actual beat frequency signal. The detailed explanation is as follows. The quadratic curve of the detection wave is expressed as follows:

[0109] f0(t)=f c +Kt 2 (3)

[0110] Among them, f c is the scanning starting frequency, K=B / D 2 is the sweep coefficient, B is the sweep bandwidth, and D is the sweep period.

[0111] The instantaneous phase information of the beat frequency signal is:

[0112]

[0113] The beat frequency signal is processed, after a fixed delay and mixing (multiplication) (this process is similar to optical coherent detection, and the instantaneous phase is delayed-subtracted), and the following is obtained:

[0114]

[0115] Formula (5) is a linear function of t, which means that the result of the processing is a point frequency (i.e., a single frequency), and its frequency is 2Kdd0 (i.e., the slope after the subtraction process). After obtaining the frequency value by FFT search, since the two parameters K and d0 are known, the value of d can be obtained, that is, the distance information of the target object can be obtained.

[0116] Add the characteristic term -2πKdt to the instantaneous phase of the beat frequency signal 2 +Kd 2 , so that the processing result is a frequency of f d The frequency value of the point frequency signal is obtained through FFT search, and the speed of the target can be obtained.

[0117] After obtaining the linear function of t (Formula 5), ​​the above method can obtain the corresponding distance d and speed v of the target object by searching for the corresponding frequency value.

[0118] In the above-mentioned embodiment of the present invention, the "sensing ability" of the nonlinear frequency sweep signal used for the target distance and speed information is completely independent: that is, for any state of the detected target, the phase information of the beat signal caused by it is uniquely determined. Utilizing this characteristic, the decoupling and separation of the target distance and speed and the subsequent signal processing process can be completed without using time division multiplexing and double-sideband modulation. The advantage of the present invention is that it can complete the decoupling and separation of distance / speed within a single frequency sweep cycle, maintaining the detection probability of the system from being deteriorated; at the same time, the modulation form of the single sideband can make the system achieve a higher sensitivity, and at the same time, there is no need to add additional devices such as intensity modulators and phase modulators, reducing the cost and complexity of the system.

[0119] like Figure 7 The present invention also relates to a radar 200, such as a FMCW laser radar, comprising: a transmitting unit 210, a receiving unit 220, and a control unit 230. The transmitting unit 210 is configured to transmit a detection wave L1 to detect a target object, and the detection wave is a nonlinear swept frequency modulation signal. The receiving unit is configured to receive an echo L1' reflected by the detection wave L1 on the target object and output an echo signal. The control unit is coupled to the transmitting unit and the detection unit and receives the echo signal, and the control unit is configured to obtain an actual beat signal based on the echo and the detection wave, and obtain the distance and / or speed of the target object based on the actual beat signal. The control unit may have built-in software, firmware or dedicated circuits to execute the method 100 described above with reference to Figures 1-6.

[0120] According to an embodiment of the present invention, the control unit 230 pre-stores a plurality of pre-stored beat frequency signals corresponding to different distances and / or speeds, and the control unit 230 may be configured as follows:

[0121] matching the phase function of the actual beat frequency signal with the phase functions of the plurality of pre-stored beat frequency signals respectively;

[0122] selecting a pre-stored beat frequency signal that has the highest degree of matching with the actual beat frequency signal;

[0123] The distance and / or speed corresponding to the pre-stored beat signal with the highest matching degree is used as the distance and / or speed of the target object.

[0124] Optionally, the plurality of pre-stored beat frequency signals correspond to different distances respectively, wherein the control unit is configured to:

[0125] Selecting a pre-stored beat signal having a waveform shape that best matches the actual beat signal;

[0126] Using the distance measurement information corresponding to the pre-stored beat frequency signal with the highest matching degree as the distance of the target object;

[0127] The speed of the target object is determined according to the frequency difference between the actual beat frequency signal and the pre-stored beat frequency signal with the highest matching degree.

[0128] Optionally, the plurality of pre-stored beat frequency signals correspond to different combinations of distances and speeds, respectively.

[0129] Wherein the control unit is configured as:

[0130] Selecting a pre-stored beat signal that has the highest degree of matching of the waveform shape and position of the actual beat signal;

[0131] The distance and speed corresponding to the pre-stored beat signal with the highest matching degree are used as the distance and speed of the target object.

[0132] Optionally, the nonlinear frequency sweep modulation signal is a quadratic curve function. According to a preferred embodiment of the present invention, the control unit is configured as follows:

[0133] Obtaining instantaneous phase information of the actual beat frequency signal;

[0134] Subtracting the instantaneous phase information of the actual beat frequency signal from the phase information of its delayed signal;

[0135] Based on the slope of the phase difference between the two, obtaining the distance information of the target object;

[0136] The speed of the target object is obtained according to the distance information and the instantaneous phase information of the actual beat frequency signal.

[0137] The present invention further relates to a computer-readable storage medium on which a computer program code executable by a processor is stored. When the code is executed by one or more processors, the processors are caused to perform the method 100 as described above.

[0138] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting using a frequency modulated continuous wave, comprising the following steps: Transmitting a detection wave to detect a target object, wherein the detection wave is a nonlinear swept frequency modulation signal; Receiving an echo after the detection wave is reflected on the target object; Obtaining an actual beat frequency signal according to the echo and the detection wave; and Obtaining the distance and / or speed of the target object according to the actual beat frequency signal, Wherein, the method further comprises: acquiring a plurality of pre-stored beat frequency signals corresponding to different distances and / or speeds; The step of obtaining the distance and / or speed of the target object according to the actual beat frequency signal further comprises: matching the phase function of the actual beat frequency signal with the phase functions of the plurality of pre-stored beat frequency signals respectively; selecting a pre-stored beat frequency signal that has the highest degree of matching with the actual beat frequency signal; The distance and / or speed corresponding to the pre-stored beat signal with the highest matching degree is used as the distance and / or speed of the target object.

2. The method of claim 1, wherein: The plurality of pre-stored beat frequency signals correspond to different distances respectively, wherein the step of selecting a pre-stored beat frequency signal that has the highest matching degree with the actual beat frequency signal further comprises: Selecting a pre-stored beat signal having a waveform shape that best matches the actual beat signal; Using the distance measurement information corresponding to the pre-stored beat frequency signal with the highest matching degree as the distance of the target object; Wherein, the step of obtaining the distance and / or speed of the target object according to the actual beat frequency signal further includes: The speed of the target object is determined according to the frequency difference between the actual beat frequency signal and the pre-stored beat frequency signal with the highest matching degree.

3. The method of claim 1, wherein: The plurality of pre-stored beat frequency signals correspond to different combinations of distances and speeds, respectively, and the step of selecting a pre-stored beat frequency signal having the highest matching degree with the actual beat frequency signal further comprises: Selecting a pre-stored beat signal that has the highest matching degree between the waveform shape and position of the actual beat signal; The distance and speed corresponding to the pre-stored beat signal with the highest matching degree are used as the distance and speed of the target object. The method according to claim 1 , wherein the nonlinear swept frequency modulation signal is a quadratic curve function.

5. The method according to claim 4, wherein the step of obtaining the distance and / or speed of the target object according to the actual beat frequency signal further comprises: Obtaining instantaneous phase information of the actual beat frequency signal; Subtracting the instantaneous phase information of the actual beat frequency signal from the phase information of its delayed signal; Based on the slope of the phase difference between the two, obtaining the distance information of the target object; The speed of the target object is obtained according to the distance information and the instantaneous phase information of the actual beat frequency signal.

6. A radar comprising: A transmitting unit, wherein the transmitting unit is configured to transmit a detection wave to detect a target object, wherein the detection wave is a nonlinear swept frequency modulation signal; a receiving unit, configured to receive an echo reflected by the detection wave on the target object and output an echo signal; a control unit, the control unit being coupled to the laser and the detection unit and receiving the echo signal, the control unit being configured to obtain an actual beat signal according to the echo and the detection wave, and to obtain a distance and / or a speed of the target object according to the actual beat signal, wherein the control unit pre-stores a plurality of pre-stored beat frequency signals corresponding to different distances and / or speeds; Wherein the control unit is configured as: matching the phase function of the actual beat frequency signal with the phase functions of the plurality of pre-stored beat frequency signals respectively; selecting a pre-stored beat frequency signal that has the highest degree of matching with the actual beat frequency signal; The distance and / or speed corresponding to the pre-stored beat signal with the highest matching degree is used as the distance and / or speed of the target object.

7. The radar according to claim 6, wherein the plurality of pre-stored beat frequency signals correspond to different distances respectively, and wherein the control unit is configured to: Selecting a pre-stored beat signal having a waveform shape that best matches the actual beat signal; Using the distance measurement information corresponding to the pre-stored beat frequency signal with the highest matching degree as the distance of the target object; The speed of the target object is determined according to the frequency difference between the actual beat frequency signal and the pre-stored beat frequency signal with the highest matching degree.

8. The radar according to claim 6, wherein the plurality of pre-stored beat frequency signals correspond to different combinations of distances and velocities, respectively. Wherein the control unit is configured as: Selecting a pre-stored beat signal that has the highest matching degree between the waveform shape and position of the actual beat signal; The distance and speed corresponding to the pre-stored beat signal with the highest matching degree are used as the distance and speed of the target object.

9. The radar according to claim 6, wherein the nonlinear swept frequency modulation signal is a quadratic curve function.

10. The radar according to claim 9, wherein the control unit is configured to: Obtaining instantaneous phase information of the actual beat frequency signal; Subtracting the instantaneous phase information of the actual beat frequency signal from the phase information of its delayed signal; Based on the slope of the phase difference between the two, obtaining the distance information of the target object; The speed of the target object is obtained according to the distance information and the instantaneous phase information of the actual beat frequency signal.

11. A computer-readable storage medium having stored thereon computer program codes executable by a processor, wherein when the codes are executed by one or more processors, the processors are caused to perform the method according to any one of claims 1 to 5.

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