Signal transmission method and apparatus, signal processing method and apparatus, and radar system

Abstract

A signal transmission method and apparatus, a signal processing method and apparatus, and a radar system (1401), which are applied to the field of sensors. The signal transmission method comprises: generating an FMCW signal (801), wherein the FMCW signal comprises a plurality of chirp signals, and time intervals between every two adjacent chirp signals among the plurality of chirp signals are different; and transmitting the FMCW signal (802). When FFT processing is performed on an echo signal, which is formed by an FMCW signal after being reflected by one or more targets, and has been subjected to frequency-mixing processing, the phenomenon of spectral peak energy broadening is avoided. Compared with an existing solution, the present disclosure can improve the detection probability and measurement precision.

Description

Signal transmission method and device, signal processing method and device, and radar system Technical Field

[0001] The present application relates to the field of sensors, and in particular to a signal transmission method and device, a signal processing method and device, and a radar system. Background Art

[0002] With the development of autonomous driving technology, more and more sensors are being used in autonomous driving systems, such as high-definition cameras, lidar, and millimeter-wave radar. Millimeter-wave radar is suitable for all-weather operation and can be used in short-range, medium-range, and long-range applications. Currently, frequency-modulated continuous wave (FMCW) radar is a relatively common type of millimeter-wave radar.

[0003] FMCW radar transmits an FMCW signal with a time-varying frequency and receives an echo signal corresponding to the transmitted FMCW signal. The difference between the echo signal's frequency and the transmitted signal's frequency allows for target location and relative velocity measurement. Because FMCW offers excellent target range and velocity measurement capabilities, it can generally measure target distance without ambiguity and target velocity with ambiguity. The time-frequency characteristics of an FMCW signal include a linear variation in the frequency of the transmitted signal over time. Each linear variation segment is called a chirp, and multiple (e.g., 256 or 512) chirps transmitted sequentially constitute a frame.

[0004] Each chirp in a traditional FMCW signal has the same starting frequency. In a typical frequency-stepped FMCW signal, each chirp is still an FMCW signal; the difference is that the starting frequency of each chirp varies linearly. In practical applications, FMCW radars that transmit typical frequency-stepped FMCW signals for target detection, distance measurement, and speed measurement suffer from low accuracy.

[0005] Summary of the Invention

[0006] The present application provides a signal transmission method and device, a signal processing method and device, and a radar system to improve the accuracy of target detection by FMCW radar.

[0007] In a first aspect, an embodiment of the present application provides a signal transmission method, the method comprising: generating a frequency modulated continuous wave (FMCW) signal, the FMCW signal comprising a plurality of chirp signals; transmitting the FMCW signal, wherein the time interval between the j-th chirp signal (i.e., the j-th chirp signal arranged in chronological order) and the (j-1)-th chirp signal in the FMCW signal satisfies the following formula:

[0008] Among them, T′ c,j-1 is the time interval between the jth chirp signal and the (j-1)th chirp signal, T j is the starting time of the j-th chirp signal, T j-1 is the starting time of the (j-1)th chirp signal, f c,1 is the starting frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step size of the starting frequencies of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1.

[0009] In the embodiment of the present application, the time interval between the j-th chirp signal and the (j-1)-th chirp signal of the transmitted FMCW signal satisfies the above formula, so that the echo signal formed after the FMCW signal is reflected by one or more targets satisfies the following formula after mixing processing (that is, the expression of the echo signal after mixing processing satisfies the following formula): Wherein, i is an imaginary unit, R is the distance of the one or more targets, j is the index of the j-th chirp signal of the FMCW signal in time, c is the speed of light, and f h is the bandwidth of a single chirp signal, Tc is the effective time of the chirp signal, f c,jis the starting frequency of the jth chirp signal, T is the sampling interval, k is the sampling index within a single chirp signal, and v is the velocity of the one or more targets. In an existing detection scheme that transmits a stepped FMCW signal, the time intervals between all temporally adjacent chirp signals in the transmitted FMCW signal are equal. After reflection from one or more targets, the echo signal formed by this FMCW signal, after frequency mixing, contains a squared term (or quadratic term) of j. Performing a fast Fourier transform (FFT) on this echo signal after frequency mixing results in spectral peak energy broadening, affecting detection probability and measurement accuracy. In an embodiment of the present application, the echo signal formed after the FMCW signal is reflected by one or more targets is mixed and processed to satisfy the above formula, which includes the first-order term of j and does not include the square term of j (or called the quadratic term), so that the phase characteristics of the high-speed moving target change linearly in the second-dimensional signal. When the echo signal after the mixing processing is processed by FFT, there will be no spectrum peak energy broadening phenomenon, which can improve the detection probability and measurement accuracy compared with the existing scheme.

[0010] In a possible implementation, the

[0011] In a possible implementation, the

[0012] In a possible implementation, the

[0013] In a possible implementation, the

[0014] In a possible implementation, X=T′ c,1 (f c,1 +f s ), T′ c,1 T′ is the time interval between the first chirp signal and the second chirp signal of the FMCW signal. c,1 It may be the time interval between the starting moment (or the emission moment) of the first chirp signal of the FMCW signal and the starting moment of the second chirp signal of the FMCW signal.

[0015] In this implementation, X = T' c,1 (f c,1 +f s ), the echo signal formed by the FMCW signal reflected by one or more targets can be mixed and processed without spectrum peak energy broadening during FFT processing, thereby improving the detection probability and measurement accuracy.

[0016] In one possible implementation, T′ c,1 The value range is 1 to 100us.

[0017] In this implementation, T′ c,1 The value range is 1 to 100us. The FMCW signal has better performance in measuring distance and speed.

[0018] In one possible implementation, the time intervals between two adjacent chirp signals in the multiple chirp signals are different. In the present application, the time interval between two chirp signals may be the time interval between the start moments of the two chirp signals. The different time intervals between two adjacent chirp signals in the multiple chirp signals means that the time interval between two adjacent chirp signals in the multiple chirp signals is not a fixed value. Exemplarily, the time interval between the jth chirp signal and the (j-1)th chirp signal of the FMCW signal in time is not equal to the time interval between the first chirp signal and the second chirp signal of the FMCW signal in time.

[0019] In a possible implementation, starting frequencies of the multiple chirp signals vary linearly.

[0020] In a possible implementation, the waveform of the FMCW signal is a stepped FMCW waveform. In other words, the FMCW signal is a stepped FMCW signal.

[0021] In one possible implementation, the FMCW signal includes 256 chirp signals. The number of chirp signals included in the FMCW signal provided in this application is not limited.

[0022] In a possible implementation, the FMCW signal includes 512 chirp signals.

[0023] In a second aspect, an embodiment of the present application provides a signal receiving method, the method comprising: receiving an echo signal, wherein the echo signal is formed by an FMCW signal reflected by one or more targets, the FMCW signal comprising multiple chirp signals, and the time interval between the j-th chirp signal and the (j-1)-th chirp signal of the FMCW signal in time satisfies the following formula:

[0024] Among them, T′ c,j-1 is the time interval between the jth chirp signal and the (j-1)th chirp signal, T j is the starting time (transmitting time) of the j-th chirp signal, T j-1 is the starting time of the (j-1)th chirp signal, fc,1 is the starting frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step amount of the starting frequency of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1; based on the echo signal, at least one of the distance and speed of the one or more targets is determined.

[0025] In the embodiment of the present application, the time interval between the j-th chirp signal and the (j-1)-th chirp signal of the transmitted FMCW signal satisfies the above formula, so that the echo signal formed after the FMCW signal is reflected by one or more targets satisfies the following formula after mixing processing (that is, the expression of the echo signal after mixing processing satisfies the following formula): Wherein, i is an imaginary unit, R is the distance of the one or more targets, j is the index of the j-th chirp signal of the FMCW signal in time, c is the speed of light, and f h is the bandwidth of a single chirp signal, Tc is the effective time of the chirp signal, f c,j is the starting frequency of the j-th chirp signal, T is the sampling time interval, k is the sampling index within a single chirp signal, and v is the speed of the one or more targets. In an existing detection scheme by transmitting a stepped FMCW signal, the time intervals between all temporally adjacent chirp signals in the transmitted FMCW signal are equal. The echo signal formed by the FMCW signal after being reflected by one or more targets includes a square term of j (or a quadratic term) in the expression after mixing processing. When the echo signal after mixing processing is subjected to fast Fourier transform (FFT), there will be a phenomenon of spectral peak energy broadening, affecting the detection probability and measurement accuracy. In the embodiment of the present application, the received echo signal after mixing processing satisfies the above formula including a linear term of j and not including a square term of j (or a quadratic term). This can make the phase characteristics of the high-speed moving target change linearly in the second-dimensional signal. When the echo signal after mixing processing is subjected to FFT processing, there will be no spectral peak energy broadening. Compared with the existing scheme, the detection probability and measurement accuracy can be improved.

[0026] In a possible implementation, the

[0027] In a possible implementation, the

[0028] In a possible implementation, the

[0029] In a possible implementation, the

[0030] In a possible implementation, X=T′ c,1 (f c,1 +f s ), T′ c,1 is the time interval between the first chirp signal and the second chirp signal of the FMCW signal.

[0031] In one possible implementation, T′ c,1 The value range is 1 to 100us.

[0032] In this implementation, T′ c,1 The value range is 1 to 100us. The FMCW signal has better performance in measuring distance and speed.

[0033] In one possible implementation, determining at least one of the distance and speed of the one or more targets based on the echo signal includes: performing mixing processing on the FMCW signal and the echo signal to obtain a mixed echo signal; and determining at least one of the distance and speed of the one or more targets based on the mixed echo signal; wherein an expression of the mixed echo signal satisfies the following formula:

[0034] Wherein, i is an imaginary unit, R is the distance of the one or more targets, j is the index of the j-th chirp signal of the FMCW signal in time, c is the speed of light, and f h is the bandwidth of a single chirp signal, Tc is the effective time of the chirp signal, f c,j is the starting frequency of the j-th chirp signal, T is the sampling time interval, k is the sampling index within a single chirp signal, and v is the speed of the one or more targets.

[0035] In this implementation, the expression of the echo signal after mixing processing includes the linear term of j but does not include the square term of j (or quadratic term). FFT processing of the echo signal after mixing processing will not cause spectrum peak energy broadening, which can improve the detection probability and measurement accuracy compared with existing solutions.

[0036] In a possible implementation, starting frequencies of the multiple chirp signals vary linearly.

[0037] In a possible implementation, the waveform of the FMCW signal is a stepped FMCW waveform. In other words, the FMCW signal is a stepped FMCW signal.

[0038] In one possible implementation, the FMCW signal includes 256 chirp signals. The number of chirp signals included in the FMCW signal provided in this application is not limited.

[0039] In a possible implementation, the FMCW signal includes 512 chirp signals.

[0040] In a third aspect, an embodiment of the present application provides a signal transmission device, comprising: a transmitting module for transmitting an FMCW signal, wherein the FMCW signal includes multiple chirp signals; wherein the time interval between the j-th chirp signal and the (j-1)-th chirp signal in time of the FMCW signal satisfies the following formula:

[0041] Among them, T′ c,j-1 is the time interval between the jth chirp signal and the (j-1)th chirp signal, T j is the starting time of the j-th chirp signal, T j-1 is the starting time of the (j-1)th chirp signal, f c,1 is the starting frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step size of the starting frequencies of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1.

[0042] In a possible implementation, X=T′ c,1 (f c,1 +f s ), T′ c,1 is the time interval between the first chirp signal and the second chirp signal of the FMCW signal.

[0043] Possible implementations of the signal transmission device of the third aspect can refer to the various possible implementations of the first aspect.

[0044] For the technical effects brought about by various possible implementations of the third aspect, reference may be made to the introduction to the technical effects of various possible implementations of the first aspect.

[0045] In a fourth aspect, an embodiment of the present application provides a signal processing device, the signal processing device comprising: a receiving module for an echo signal, wherein the echo signal is formed by an FMCW signal reflected by one or more targets, the FMCW signal comprising multiple chirp signals, and the time interval between the j-th chirp signal and the (j-1)-th chirp signal in time of the FMCW signal satisfies the following formula:

[0046] Among them, T′ c,j-1 is the time interval between the jth chirp signal and the (j-1)th chirp signal, T j is the starting time of the j-th chirp signal, T j-1 is the starting time of the (j-1)th chirp signal, f c,1 is the starting frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step size between the starting frequencies of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1; performing at least frequency mixing, filtering, and analog-to-digital conversion on the echo signal to obtain a digital signal; and a processing module for determining at least one of the range and speed of the one or more targets based on the digital signal.

[0047] In a possible implementation, X=T′ c,1 (f c,1 +f s ), T′ c,1 is the time interval between the first chirp signal and the second chirp signal of the FMCW signal.

[0048] In one possible implementation, T′ c,1 The value range is 1 to 100us.

[0049] In one possible implementation, the receiving module is further configured to perform mixing processing based on the FMCW signal and the echo signal to obtain a mixed echo signal; and the processing module is specifically configured to determine at least one of the distance and speed of the one or more targets based on the mixed echo signal; wherein the expression of the mixed echo signal satisfies the following formula:

[0050] Wherein, i is an imaginary unit, R is the distance of the one or more targets, j is the index of the j-th chirp signal of the FMCW signal in time, c is the speed of light, and f h is the bandwidth of a single chirp signal, Tc is the effective time of the chirp signal, f c,j is the starting frequency of the j-th chirp signal, T is the sampling time interval, k is the sampling index within a single chirp signal, and v is the speed of the one or more targets.

[0051] Possible implementations of the signal processing device of the fourth aspect can refer to the various possible implementations of the second aspect.

[0052] For the technical effects brought about by various possible implementation methods of the fourth aspect, reference may be made to the introduction to the technical effects of various possible implementation methods of the second aspect.

[0053] In a fifth aspect, an embodiment of the present application provides a radar system, characterized in that it includes: a transmitting module for transmitting an FMCW signal, wherein the FMCW signal includes multiple chirp signals; wherein the time interval between the j-th chirp signal and the (j-1)-th chirp signal in time of the FMCW signal satisfies the following formula:

[0054] Among them, T′ c,j-1 is the time interval between the jth chirp signal and the (j-1)th chirp signal, T j is the starting time of the j-th chirp signal, T j-1 is the starting time of the (j-1)th chirp signal, f c,1 is the starting frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step size between the starting frequencies of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1; a receiving module is used to receive an echo signal, where the echo signal is formed after the FMCW signal is reflected by one or more targets; based on the echo signal, at least frequency mixing, filtering, and analog-to-digital conversion are performed to obtain a digital signal; and a processing module is used to determine at least one of the distance and speed of the one or more targets based on the digital signal.

[0055] In an embodiment of the present application, the echo signal formed after the FMCW signal is reflected by one or more targets satisfies the above formula after mixing processing, including the first-order term of j and not including the square term of j (or called the second-order term). FFT processing of the echo signal after mixing processing will not cause spectrum peak energy broadening, which can improve the detection probability and measurement accuracy compared with existing solutions.

[0056] In one possible implementation, the receiving module is configured to perform mixing processing based on the FMCW signal and the echo signal to obtain a mixed echo signal; the processing module is specifically configured to determine at least one of the distance and speed of the one or more targets based on the mixed echo signal; wherein the expression of the mixed echo signal satisfies the following formula:

[0057] Wherein, i is an imaginary unit, R is the distance of the one or more targets, j is the index of the j-th chirp signal of the FMCW signal in time, c is the speed of light, and f h is the bandwidth of a single chirp signal, Tc is the effective time of the chirp signal, f c,jis the starting frequency of the j-th chirp signal, T is the sampling time interval, k is the sampling index within a single chirp signal, and v is the speed of the one or more targets.

[0058] In this implementation, the expression of the echo signal after mixing processing includes the linear term of j but does not include the square term of j (or quadratic term). FFT processing of the echo signal after mixing processing will not cause spectrum peak energy broadening, which can improve the detection probability and measurement accuracy compared with existing solutions.

[0059] Possible implementations of the radar system of the fifth aspect can refer to the various possible implementations of the first aspect and the various possible implementations of the second aspect.

[0060] For the technical effects brought about by various possible implementation methods of the fifth aspect, reference may be made to the introduction to the technical effects of various possible implementation methods of the first aspect and the introduction to the technical effects of various possible implementation methods of the second aspect.

[0061] In a sixth aspect, an embodiment of the present application provides a terminal device, which includes a radar system as described in the fifth aspect or any possible implementation of the fifth aspect.

[0062] In a seventh aspect, an embodiment of the present application provides a signal generator for generating an FMCW signal, wherein the FMCW signal includes multiple chirp signals; wherein the time interval between the j-th chirp signal and the (j-1)-th chirp signal in time of the FMCW signal satisfies the following formula:

[0063] Among them, T′ c,j-1 is the time interval between the jth chirp signal and the (j-1)th chirp signal, T j is the starting time of the j-th chirp signal, T j-1 is the starting time of the (j-1)th chirp signal, f c,1 is the starting frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step size of the starting frequencies of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1. Exemplarily, the signal generator is a voltage-controlled oscillator or other oscillators.

[0064] Possible implementations of the signal transmission device of the seventh aspect can refer to the various possible implementations of the first aspect.

[0065] For the technical effects brought about by various possible implementation methods of the seventh aspect, reference may be made to the introduction to the technical effects of various possible implementation methods of the first aspect.

[0066] In an eighth aspect, the present application provides another signal transmission device, which includes a processing circuit and an interface circuit, wherein the interface circuit is used to acquire a signal or output a signal; the processing circuit is used to execute the method shown in the first aspect or any possible implementation of the first aspect.

[0067] In a ninth aspect, the present application provides another signal processing device, which includes a processing circuit and an interface circuit, wherein the interface circuit is used to acquire a signal or output a signal; the processing circuit is used to execute the method shown in the second aspect or any possible implementation of the second aspect.

[0068] In a tenth aspect, the present application provides a computer-readable storage medium, which stores a computer program. The computer program includes program instructions, which, when executed, enable the computer to execute the method shown in the first aspect or the second aspect above.

[0069] In an eleventh aspect, the present application provides a computer program product, which includes a computer program, and the computer program includes program instructions. When the program instructions are executed, the computer executes the method shown in the first aspect or the second aspect above.

[0070] In the twelfth aspect, the present application provides a chip comprising a communication interface and a processor; the communication interface is used for transmitting and receiving signals of the chip; the processor is used for executing computer program instructions so that a communication device comprising the chip executes the method shown in the above-mentioned first aspect or the above-mentioned second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] FIG1 shows an example of a waveform diagram of a linear frequency modulated continuous wave;

[0072] FIG2 is a schematic diagram showing the time-frequency characteristics of a conventional FMCW signal;

[0073] FIG3 is a schematic diagram showing the time-frequency characteristics of two stepped FMCW signals;

[0074] FIG4 is a schematic diagram of a radar system provided in an embodiment of the present application installed in a car;

[0075] FIG5 is a schematic diagram of a possible application scenario provided by this application;

[0076] FIG6 shows the main lobe broadening at different speeds obtained by performing FFT processing on the mixed signal of the echo signal of a typical stepped FMCW signal;

[0077] FIG7 shows the main lobe broadening at different speeds obtained by performing FFT processing on the mixed signal of the echo signal of the non-equally spaced frequency-stepped FMCW signal;

[0078] FIG8 is a flow chart of a signal transmission method provided in an embodiment of the present application;

[0079] FIG9 is a schematic diagram of a possible structure of a transmitting module provided in this application;

[0080] FIG10 is a flow chart of a signal processing method provided in an embodiment of the present application;

[0081] FIG11 is a schematic diagram of a possible structure of a receiving module provided in this application;

[0082] FIG12 is a flow chart of a detection method provided in an embodiment of the present application;

[0083] FIG13 is a schematic structural diagram of a radar system provided by the present application;

[0084] FIG14 is a schematic structural diagram of a terminal device provided in this application. DETAILED DESCRIPTION

[0085] The terms "first" and "second" in the specification, claims and drawings of the present application are only used to distinguish different objects, rather than to describe a specific order. It will be understood that the various digital numbers involved in the embodiments of the present application are only for the convenience of description and are not used to limit the scope of the embodiments of the present application. The size of the sequence number of each of the above processes does not mean the order of execution, and the order of execution of each process should be determined by its function and inherent logic. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0086] The "embodiment" mentioned in this document means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It can be understood explicitly and implicitly by those skilled in the art that the embodiments described herein can be combined with other embodiments. In this application, the naming of messages is only used to distinguish different messages and should not be understood as a limitation. In other words, the name of any message in this application can be replaced with other names, and this application is not limited.

[0087] The terms used in the following embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification of the present application and the appended claims, the singular expressions "one", "a kind of", "above", "above", "the" and "this" are intended to also include plural expressions, unless there is a clear contrary indication in the context. It should also be understood that the term "and / or" used in the present application refers to and includes any or all possible combinations of one or more listed items. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The term "multiple" used in the present application refers to two or more. In the textual description of the present application, the character " / " generally indicates that the objects associated before and after are in an "or" relationship.

[0088] It is understood that in each embodiment of the present application, "A corresponds to B" means that there is a corresponding relationship between A and B, and B can be determined according to A. However, it should also be understood that determining (or generating) B according to (or based on) A does not mean that B is determined (or generated) only according to (or based on) A, and B can also be determined (or generated) according to (or based on) A and / or other information.

[0089] It should be understood that, in this application, indication includes direct indication (also known as explicit indication) and implicit indication. Direct indication of information A refers to including information A; implicit indication of information A refers to indicating information A through the correspondence between information A and information B and the direct indication of information B. The correspondence between information A and information B can be predefined, pre-stored, pre-burned, or pre-configured.

[0090] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "exemplary" or "for example" should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0091] It should be understood that, in this application, information C is used to determine information D, which includes both information D being determined solely based on information C and information D being determined based on information C and other information. Furthermore, information C can also be used to determine information D indirectly, for example, where information D is determined based on information E, and information E is determined based on information C.

[0092] To facilitate understanding, some of the terms used in the embodiments of this application are explained below.

[0093] Millimeter waves are electromagnetic waves with wavelengths between 1 and 10 mm, corresponding to a frequency range of 30 to 300 GHz. In this frequency band, millimeter waves possess characteristics that are well-suited for automotive applications. For example, they offer wide bandwidth, rich frequency domain resources, and low antenna sidelobes, facilitating imaging or quasi-imaging. Their short wavelength reduces the size and antenna diameter of radar equipment, reducing weight. Their narrow beams are much narrower than microwave beams for the same antenna size, resulting in higher radar resolution. Millimeter waves also offer strong penetration, making them more capable of penetrating smoke, dust, and fog than lidar and optical systems, enabling all-weather operation.

[0094] Frequency Modulated Continuous Wave: An electromagnetic wave whose frequency varies with time.

[0095] Linearly swept frequency modulated continuous wave (LFMCCW): A frequency modulated continuous wave whose frequency varies linearly over time. Linear variation generally refers to a linear change within a cycle. The waveform of the frequency change is typically a sawtooth or triangle wave, but other waveforms, such as pulses, are also possible. Figure 1 shows an example of a LFM continuous wave waveform diagram.

[0096] Linear frequency modulation signal: A type of pulse signal. Also known as a chirp signal, a linear frequency modulation signal is an electromagnetic wave signal whose frequency varies linearly with time. The linear variation here generally refers to a linear variation within a single transmission cycle. For example, the waveform of the linear frequency modulation signal can be a sawtooth wave, a triangle wave, or other possible waveforms, which are encompassed but not limited to by this application.

[0097] FMCW signal: It is a linear frequency modulated continuous wave. The frequency of the FMCW signal changes linearly with time. Each linear change segment is a chirp signal (i.e., a pulse). Multiple (for example, 256 or 512) chirps are sent sequentially to form a frame. One frame corresponds to one frame period. In other words, the FMCW signal includes multiple chirp signals, each chirp signal corresponding to a time period in which the frequency changes linearly with time. The starting frequency of each chirp signal in a traditional FMCW signal is the same. Figure 2 shows a schematic diagram of the time-frequency characteristics of a traditional FMCW signal. As shown in Figure 2, the starting frequency of each chirp signal in a traditional FMCW signal is the same, and the time intervals between all temporally adjacent chirp signals are equal, that is, the time interval between two temporally adjacent chirp signals is a fixed value. The difference between a stepped FMCW signal and a traditional FMCW signal is that the starting frequency of the chirp signal in the stepped FMCW signal changes linearly. Figure 3 shows a schematic diagram of the time-frequency characteristics of two stepped FMCW signals. As shown in Figure 3, the starting frequency of the chirp signal in a stepped FMCW signal can be linearly increased or decreased. Compared to traditional FMCW signals, stepped FMCW signals can increase the total bandwidth of a signal frame. This is because the bandwidth of a frame is the sum of the bandwidth of a single chirp signal and the step bandwidth. In principle, increasing the bandwidth can improve the radar's range resolution.

[0098] Millimeter-wave radar operates in the millimeter-wave band and generally consists of a transmitter module, a receiver module, and a processing module. The transmitter module generates a radar signal whose frequency increases linearly with time. This radar signal is typically an FMCW signal. Part of this radar signal is output to the mixer in the receiver module as a local oscillator (LO) signal (e.g., via a directional coupler). Part of this signal is transmitted by the transmitter module (e.g., via a directional coupler). The receiver module receives the radar signal reflected from the target (also known as the reflected signal or echo signal). The mixer in the receiver module mixes the received echo signal with the LO signal to generate an intermediate frequency (IF) signal (also known as an IF echo signal). The IF signal contains information such as the relative distance, velocity, and angle between the target and the radar system. After passing through a low-pass filter and amplification, the IF signal is transmitted to the processing module. The processing module processes the received signal, performing techniques such as fast Fourier transform and spectrum analysis, to determine the target's distance, velocity, and angle relative to the radar system. Finally, the processing module can output the obtained information to the controller to control the behavior of the vehicle.

[0099] The radars mentioned in the embodiments of the present application may be frequency modulated continuous wave (FMCW) radars, FMCW lidars, and other radars or detection devices that transmit FMCW signals for detection. The radars in the embodiments of the present application can be applied to various fields such as intelligent transportation, autonomous driving, atmospheric environment monitoring, geographic mapping, and drones, and can perform one or more functions including target detection, distance measurement, speed measurement, target tracking, and image recognition.

[0100] Doppler bin: The frequency interval or resolution in the Doppler domain of a spectrum obtained by fast Fourier transform (FFT) of data. This frequency interval is usually determined by the sampling rate and the number of sampling points, e.g., Doppler bin = sampling rate / number of sampling points.

[0101] Frequency step size fs, also known as step bandwidth, measures the frequency offset between two adjacent chirp signals. Specifically, the frequency offset between two adjacent chirp signals can be determined by their starting frequencies. As shown in Figure 3, the frequency offset between two adjacent chirp signals is determined by their starting frequencies. The offset between the starting frequencies of the first and second chirp signals is fs.

[0102] Range resolution refers to the resolution in the distance dimension, specifically the minimum distance between two targets that a radar can distinguish. For example, when the trailing edge (falling edge) of a pulse from a closer target coincides with the leading edge (rising edge) of a pulse from a farther target, the distance between the two targets is the limit of resolution.

[0103] Detection device: The detection device referred to in this application may be a radar (or radar device) or other device for detection (e.g., a rangefinder). Its operating principle is to detect the corresponding target object by transmitting a signal (or detection signal) and receiving a reflected signal (or echo signal) reflected by the target object. Optionally, the signal transmitted by the radar may be referred to as a radar signal, and the reflected signal received by the radar after being reflected by the target object may also be referred to as a radar signal.

[0104] The previous text introduced some of the terms involved in this application. The following text introduces the possible application scenarios of this application.

[0105] In a possible application scenario, the signal transmission device, signal processing device, or radar system (or named as detection device) in the present application can be installed on a vehicle, specifically, can be installed at various positions of the vehicle. For example, the radar system can be installed in any one or more of the four directions of the front, rear, left, and right of the vehicle to achieve the capture of the vehicle's surrounding environment information. Please refer to Figure 4, the vehicle takes a car as an example, and the radar system (radar shown in Figure 4) is installed in the six directions of the front, left front, right front, left rear, rear (not shown in Figure 4), and right rear (not shown in Figure 4) of the car as an example. Figure 4 is a schematic diagram of the radar system provided in an embodiment of the present application installed on a car.

[0106] Figure 5 is a schematic diagram of a possible application scenario provided by this application. The radar system on the vehicle can sense the sector area shown in the dotted box, which can be called the detection area of ​​the radar system. The radar system can obtain information (such as the distance of the target, the moving speed of the target, or the posture of the target) of targets within a certain range (such as other vehicles or obstacles in the surrounding area) in real time or periodically. The radar system or vehicle can determine the location of the vehicle based on this information and perform path planning. For example, the number and density of obstacles around the vehicle can be determined by using the distance of surrounding objects. Furthermore, optionally, in combination with the functions of an advanced driving assistance system (ADAS), assisted driving or automatic driving of the vehicle can be achieved. It should be understood that the principle of radar system detection of targets is: the radar system transmits a signal in a certain direction. If there is a target within the detection area of ​​the radar system, the target reflects the transmitted signal back to the radar system (the reflected signal can be called an echo signal), and the radar system then determines the target information based on the echo signal.

[0107] It should be noted that the above application scenarios are only examples, and the signal transmission device, signal processing device, or radar system provided in this application can also be applied to a variety of other possible scenarios, not limited to the scenarios exemplified above. For example, the radar system can also be installed on a drone as an airborne radar system. For another example, the radar system can also be installed on a roadside unit (RSU) as a roadside traffic radar system, which can realize intelligent vehicle-road collaborative communication, etc. For another example, the radar system can be installed on an automated guided vehicle (AGV), which refers to a transport vehicle equipped with an electromagnetic or optical automatic navigation device that can travel along a specified navigation path and has safety protection and various transfer functions. The signal transmission device, signal processing device, or radar system provided in this application can be sold separately in the form of hardware, that is, the signal transmission device, signal processing device, or radar system can be sold separately, or the signal transmission device, signal processing device, or radar system can be integrated into other products, such as a vehicle-mounted millimeter wave radar.

[0108] The above application scenarios can be applied to unmanned driving, autonomous driving, assisted driving, intelligent driving, connected cars, security, remote interaction, artificial intelligence or mapping, etc. This application does not limit the installation location and function of the radar system.

[0109] With the advancement of intelligent driving technology, the role of automotive millimeter-wave radar (MMW) in vehicle sensors has become increasingly important. Vehicles require radar to detect targets at longer distances and have superior range resolution, enabling them to distinguish between two adjacent targets or report more monitoring points on a single extended target to estimate the target's outline. Because FMCW signals offer superior range and velocity measurement capabilities, typically measuring target distance without ambiguity and velocity with ambiguity, current millimeter-wave radars typically use FMCW signals as detection signals (or, in other words, FMCW waveforms). Under typical parameters, each chirp in an FMCW signal contains 1024 sampling points, and a millimeter-wave radar typically transmits 256 chirps per cycle, known as the FMCW signal. The FMCW signal is radiated into space by the transmitting antenna. After being reflected by the target, the echo signal is received by the receiving antenna. After mixing, filtering, and sampling, the echo signal undergoes two FFT processes to generate a range-Doppler spectrum, which in turn provides the target's range and velocity information. For example, after the millimeter-wave radar performs a one-dimensional FFT transformation on the echo signal of each chirp signal after mixing processing, 1024 range units can be obtained. Due to the mirror effect of the real number FFT processing, the effective number of range units is 512. After performing a second-dimensional FFT transformation on the data, the Doppler spectrum or velocity spectrum of the target can be obtained, that is, 256 Doppler units.

[0110] Since the number of distance units of the target measured by the FMCW signal is fixed, the maximum distance of the target that can be measured is also fixed at a given distance resolution. For example, if the distance resolution is 0.5m, the maximum distance that can be measured is approximately 256m. If the distance resolution is further reduced to 0.2m, the maximum distance that can be measured drops to 102.4m. In order to resolve the contradiction between distance resolution and detection range, this application adopts a stepped FMCW signal to migrate the dimension of distance resolution from the first-dimensional FFT to the second-dimensional FFT, thereby improving the distance resolution while ensuring the distance detection range. For example, by introducing a linear frequency step between chirp signals, a distance resolution of 0.2m can be achieved in the second dimension while maintaining the maximum detection distance of 256m in the first dimension.

[0111] Currently, many millimeter-wave radars use a typical stepped FMCW signal for detection, such as measuring target speed and distance. In a typical stepped FMCW signal, the time intervals between all temporally adjacent chirps are equal, meaning the time interval between two temporally adjacent chirps is a fixed value. When a millimeter-wave radar uses a typical stepped FMCW signal for detection, the echo signal received by the millimeter-wave radar's receiving antenna satisfies the following formula after frequency mixing (i.e., the expression for the echo signal after frequency mixing satisfies the following formula):

[0112] Where i is the imaginary unit, R is the distance to one or more targets, j is the index of the jth chirp signal in time of a typical stepped FMCW signal, c is the speed of light, and f h is the bandwidth of a single chirp signal, Tc is the effective time of the chirp signal (or the pulse repetition interval of the chirp signal), f c,j is the starting frequency of the j-th chirp signal, T is the sampling time interval, k is the sampling index within a single chirp signal (or the fast time sampling index), v is the speed of the target or targets, T′ c T' is the time interval between two temporally adjacent chirp signals in a typical stepped FMCW signal. c is a fixed value, and j is a slow time index, ie, the index of the chirp signal. Optionally, the echo signal after mixing is an intermediate frequency signal (or intermediate frequency echo signal) obtained by mixing the local oscillator signal and the echo signal.

[0113] Assume that the carrier frequency of the chirp signal in a typical stepped FMCW signal changes linearly with the index of the chirp signal, that is, f c,j =f c,1 +(j-1)f s, where fs is the frequency step size, and the last term in the above formula (1) satisfies the following formula:

[0114] Among them, fs is the frequency step, f c,1 is the index of the jth chirp signal in time of a typical stepped FMCW signal. The meanings of the parameters in formula (2) are the same as those in formula (1).

[0115] In formula (2), a square term appears on the j index of the second dimension. FFT processing of the echo signal after mixing will result in spectrum peak energy broadening, affecting the detection probability and measurement accuracy. Figure 6 shows the main lobe broadening at different speeds obtained by performing FFT processing on the echo signal after mixing of a typical stepped FMCW signal. As shown in Figure 6, FFT processing of the echo signal after mixing will result in spectrum peak energy broadening. It can be seen that using a typical stepped FMCW signal for detection will result in a decrease in detection probability and measurement accuracy.

[0116] To address the problem of reduced detection probability and measurement accuracy caused by using a typical stepped FMCW signal for detection, this application proposes to transmit a non-equally spaced frequency-stepped FMCW signal for detection. Compared to a typical stepped FMCW signal, the non-equally spaced frequency-stepped FMCW signal proposed in this application differs from the typical stepped FMCW signal in at least the following ways: the time interval between two adjacent chirp signals is not fixed, or the chirp emission times do not vary linearly.

[0117] The following describes how the non-equally spaced frequency-stepped FMCW signal proposed in this application is derived, and why transmitting the non-equally spaced frequency-stepped FMCW signal proposed in this application for detection can improve detection probability and measurement accuracy. When a millimeter-wave radar (or other type of radar) transmits a non-equally spaced frequency-stepped FMCW signal, the echo signal received by the millimeter-wave radar's receiving antenna satisfies the following formula after frequency mixing (i.e., the expression of the echo signal after frequency mixing satisfies the following formula):

[0118] Among them, T j is the emission time (i.e., starting time) of the jth chirp signal in the unequally spaced frequency-stepped FMCW signal, which is arranged in chronological order, T j =T j-1 +T′ c,j-1 , T j-1 T′ is the emission time of the (j-1)th chirp signal in the unequally spaced frequency-stepped FMCW signal, which is arranged in chronological order. c,j-1is the time interval between the jth chirp signal and the (j-1)th chirp signal, j = 1, 2, ..., N c , Nc is the number of chirp signals in a frame signal, that is, the number of chirp signals included in the non-equally spaced frequency-stepped FMCW signal. The meanings of the parameters in formula (3) can be referred to the meanings of the parameters in formula (1), and will not be repeated here.

[0119] From formula (3), we can see that when When the linear term of j is included and the square term of j (or quadratic term) is not included, the FFT processing of the echo signal after the mixing process will not cause the spectrum peak energy to be broadened, which can improve the detection probability and measurement accuracy compared with the existing solution. In one possible implementation, Satisfies the following formula:

[0120] Among them, f c,1 Indicates the starting frequency of the first chirp signal in the time of the non-equally spaced frequency-stepped FMCW signal, f s is the frequency step, and X is a fixed constant.

[0121] Let j = 1 in the above formula (4) and we can get T1 = 0. Substitute j = 2 into T j =T j-1 +T′ c,j-1 So, T2=T1+T′ c,1 =T′ c,1 . T′ c,1 is the time interval between the first chirp signal and the second chirp signal of the non-uniform frequency-stepped FMCW signal. Let j = 2 in the above formula (4), and we can get X = (f c,1 +f s )*T2=(f c,1 +f s )*T′ c,1 .

[0122] when When the above formula (4) is satisfied, T′ c,j-1 Satisfies the following formula (5):

[0123] Where X=(f c,1 +f s )*T′ c,1 , f s is the frequency step, f c,1 is the starting frequency of the first chirp signal in time in the non-equally spaced frequency-stepped FMCW signal.

[0124] It should be understood that when the time interval between temporally adjacent chirp signals in the non-equally spaced frequency-stepped FMCW signal satisfies formula (5), the above formula (3) is Formula (4) above is satisfied. Therefore, when performing FFT processing on the echo signal of the non-equally spaced frequency-stepped FMCW signal after frequency mixing, there is no spectrum peak energy broadening. This improves detection probability and measurement accuracy compared to existing solutions. Figure 7 shows the main lobe broadening at different speeds obtained by performing FFT processing on the echo signal of the non-equally spaced frequency-stepped FMCW signal after frequency mixing. As shown in Figure 7, there is no spectrum peak energy broadening when performing FFT processing on the echo signal after frequency mixing.

[0125] It should be noted that the above formula (4) is only an example. It can be any other linear polynomial in j. For example, The above formula (4) is As an example, the values ​​of X and Y can be calculated in a similar manner as above, which will not be described in detail here.

[0126] The signal transmission method, signal processing method, signal transmission device, signal processing device and radar system provided by the present application are respectively introduced below with reference to the accompanying drawings.

[0127] FIG8 is a flow chart of a signal transmission method provided by an embodiment of the present application. As shown in FIG8 , the method includes:

[0128] 801. A signal transmission device generates an FMCW signal.

[0129] In one possible implementation, the signal transmission device may include a transmitting module that generates an FMCW signal. The signal transmission device may also generate the FMCW signal in other ways, which are not limited in this application. For example, the signal transmission device may also include a processing module that controls a voltage-controlled oscillator to generate the FMCW signal.

[0130] In one possible implementation, the transmitting module includes a voltage controlled oscillator (VCO), a power amplifier (PA) and a transmitting antenna (TX), and the transmitting module generates an FMCW signal, which may be a voltage controlled oscillator in the transmitting module generating an FMCW signal. The voltage controlled oscillator may also be called a waveform generator (waveform generation), or may have other names, which are not limited here. The voltage controlled oscillator is used to generate an FMCW signal. Exemplarily, the voltage controlled oscillator in the transmitting module is configured to generate the above-mentioned non-equally spaced frequency stepped FMCW signal. Unless otherwise specified, the FMCW signal in the embodiment of the present application refers to the above-mentioned non-equally spaced frequency stepped FMCW signal. The above-mentioned FMCW signal includes multiple chirp signals. The starting frequencies of the above-mentioned multiple chirp signals vary linearly. Exemplarily, the above-mentioned FMCW signal includes 256 chirp signals or 512 chirp signals. In other words, 256 chirp signals or 512 chirp signals are sent in chronological order to form a frame, namely the above-mentioned FMCW signal. In this application, the number of chirp signals included in the above-mentioned FMCW signal is not limited.

[0131] In one possible implementation, the time interval between the j-th chirp signal (i.e., the j-th chirp signal arranged in chronological order) and the (j-1)-th chirp signal of the FMCW signal satisfies the following formula:

[0132] Among them, T′ c,j-1 is the time interval between the jth chirp signal and the (j-1)th chirp signal, T j is the starting time of the j-th chirp signal, T j-1 is the starting time of the (j-1)th chirp signal, f c,1 is the starting frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step size of the starting frequencies of two adjacent chirp signals in the above FMCW signal, X is a fixed value, and j is an integer greater than 1.

[0133] In one possible implementation, the time interval between the j-th chirp signal (i.e., the j-th chirp signal arranged in chronological order) and the (j-1)-th chirp signal of the FMCW signal satisfies the following formula:

[0134] The meanings of the parameters in formula (7) are the same as those in formula (6).

[0135] In one possible implementation, the time interval between the j-th chirp signal (i.e., the j-th chirp signal arranged in chronological order) and the (j-1)-th chirp signal of the FMCW signal satisfies the following formula:

[0136] The meanings of the parameters in formula (8) are the same as those in formula (6).

[0137] In one possible implementation, the time interval between the j-th chirp signal (i.e., the j-th chirp signal arranged in chronological order) and the (j-1)-th chirp signal of the FMCW signal satisfies the following formula:

[0138] The meanings of the parameters in formula (9) are the same as those in formula (6).

[0139] In one possible implementation, the time interval between the j-th chirp signal (i.e., the j-th chirp signal arranged in chronological order) and the (j-1)-th chirp signal of the FMCW signal satisfies the following formula:

[0140] The meanings of the parameters in formula (10) are the same as those in formula (6).

[0141] In a possible implementation, the above X=T′ c,1 (f c,1 +f s ), T′ c,1 T′ is the time interval between the first chirp signal and the second chirp signal of the FMCW signal. c,1 It can be the time interval between the start time (or the emission time) of the first chirp signal of the FMCW signal and the start time of the second chirp signal of the FMCW signal. c,1 The value range of T′ is 1 to 100us. c,1 The value range of T′ is 1 to 100us. The FMCW signal has better performance in measuring distance and speed. c,1 The value range of can be set according to actual needs, and this application does not limit it. In one possible implementation, T′ c,1 is pre-configured, the signal transmission device is based on the pre-configured T' c,1 Generate FMCW signal. In one possible implementation, the signal transmission device can adjust T' c,1 , thereby generating FMCW signals that meet different requirements. In this implementation, X = T' c,1 (fc,1 +f s ), the echo signal formed by the FMCW signal reflected by one or more targets can be mixed and processed without spectrum peak energy broadening during FFT processing, thereby improving the detection probability and measurement accuracy.

[0142] 802. The signal transmission device transmits the FMCW signal.

[0143] The transmitting module in the signal transmission device transmits the above-mentioned FMCW signal.

[0144] In one possible implementation, the transmitting module includes a VCO, a PA, and a transmitting antenna. The VCP generates an FMCW signal and outputs a portion of the generated FMCW signal to the PA. The PA amplifies the input signal and outputs it to the transmitting antenna. The transmitting antenna transmits the power-amplified FMCW signal.

[0145] In one possible implementation, the transmitting module includes: a VCO, a PA, a coupler, and a transmitting antenna. The transmitting module performs the following operations: the VCO generates an FMCW signal, outputs a portion of the generated FMCW signal to the PA, and outputs a portion of the generated FMCW signal via the coupler, for example, to a mixer in the receiving module; the PA amplifies the input signal and outputs it to the transmitting antenna; and the transmitting antenna transmits the power-amplified FMCW signal. Figure 9 is a schematic diagram of a possible structure of the transmitting module provided in this application. As shown in Figure 9, the transmitting module includes a VCO, a PA, a coupler, and a TX.

[0146] The above-mentioned transmitting module can be a separately salable hardware, or it can be integrated into other hardware or terminal equipment. The signal transmission device provided in the embodiment of the present application can be the above-mentioned transmitting module, that is, it only includes the transmitting module. The signal transmission device can be a separately salable hardware. The signal transmission device provided in the embodiment of the present application can include the above-mentioned transmitting module and other hardware.

[0147] In the embodiment of the present application, the time interval between the j-th chirp signal and the (j-1)-th chirp signal of the FMCW signal transmitted by the signal transmission device satisfies any one of the above formulas (6) to (10), so that the echo signal formed after the FMCW signal is reflected by one or more targets can satisfy the following formula after mixing processing (that is, the expression of the echo signal after mixing processing satisfies the following formula): In an embodiment of the present application, the echo signal formed after the FMCW signal is reflected by one or more targets is mixed and processed to satisfy the above formula, which includes the first-order term of j and does not include the square term of j (or called the quadratic term), so that the phase characteristics of the high-speed moving target change linearly in the second-dimensional signal. When the echo signal after the mixing processing is processed by FFT, there will be no spectrum peak energy broadening phenomenon, which can improve the detection probability and measurement accuracy compared with the existing scheme.

[0148] FIG10 is a flow chart of a signal processing method provided by an embodiment of the present application. As shown in FIG10 , the method includes:

[0149] 1001. A signal processing device receives an echo signal.

[0150] The signal processing device may include a receiving module. The signal processing device receiving the echo signal may include: the receiving module receiving the echo signal. The echo signal is formed by the FMCW signal (i.e., the FMCW signal transmitted by the transmitting module in FIG8 ) being reflected by one or more targets. In one possible implementation, the receiving module may include a receiving antenna (RX), and the receiving antenna in the receiving module receives the echo signal.

[0151] 1002. The signal processing device performs at least frequency mixing, filtering, and analog-to-digital conversion based on the echo signal to obtain a digital signal.

[0152] In one possible implementation, a receiving module in a signal processing device performs at least frequency mixing, filtering, and analog-to-digital conversion based on the echo signal to obtain a digital signal. Analog-to-digital conversion refers to converting an analog signal into a digital signal, for example, by using an analog-to-digital converter (ADC).

[0153] In one possible implementation, the receiving module includes a receiving antenna, a low noise amplifier (LNA), a mixer, a high pass filter (HPF), a variable gain amplifier (VGA), a low pass filter (LPF) and an ADC; the operations performed by the receiving module include: the receiving antenna receives the above-mentioned echo signal and outputs the received echo signal to the LNA; the LNA amplifies the echo signal received by the receiving antenna and outputs the amplified echo signal to the mixer; the mixer mixes the amplified echo signal with the corresponding FMCW signal (for example, the FMCW signal output by the transmitting module to the mixer via a coupler) to obtain an intermediate frequency signal; the intermediate frequency signal after filtering by the HPF, amplification by the VGA, and filtering by the LPF is converted into a digital signal by the ADC. Figure 11 is a possible structural diagram of the receiving module provided by the present application. As shown in Figure 11, the receiving module includes: RX, LNA, mixer, HPF, VGA, LPF and ADC.

[0154] The expression of the above intermediate frequency signal, that is, the echo signal after mixing processing, can satisfy the following formula:

[0155] Where i is an imaginary unit, R is the distance to the target or targets, j is the index of the j-th chirp signal in time of the FMCW signal, c is the speed of light, and f h is the bandwidth of a single chirp signal, Tc is the effective time of the chirp signal, f c,j is the starting frequency of the jth chirp signal, T is the sampling interval, k is the sampling index within a single chirp signal, and v is the velocity of the target or targets. Because the intermediate frequency signal expression includes the linear term of j but not the squared term (or quadratic term) of j, FFT processing of the mixed echo signal does not result in spectral peak energy broadening, improving detection probability and measurement accuracy compared to existing solutions.

[0156] 1003. The signal processing device determines at least one of the distance and speed of one or more targets based on the digital signal.

[0157] In one possible implementation, the signal processing device further includes a processing module, and the signal processing device determines at least one of the distance and speed of one or more targets based on the above-mentioned digital signal. It can be that: the processing module determines at least one of the distance and speed of one or more targets based on the above-mentioned digital signal.

[0158] In one possible implementation, a processing module samples and quantizes a digital signal to form a two-dimensional array of data sequences. One dimension of this two-dimensional array corresponds to the sampling point number k of the chirp signal (or the fast time dimension), and the other dimension corresponds to the chirp signal number (or the slow time dimension). A two-dimensional FFT is then performed on this two-dimensional array to obtain a range-Doppler spectrum. Based on this range-Doppler spectrum, at least one of the range and velocity of one or more targets is estimated.

[0159] Step 1002 and step 1003 are possible implementations of determining at least one of the distance and speed of the one or more targets based on the echo signal.

[0160] The signal processing device may be a separately salable piece of hardware, or may be integrated into other hardware or a terminal device. The signal transmission device provided in the embodiments of the present application may include only the receiving module and the processing module, or may include the receiving module, the processing module, and other hardware. In one possible embodiment, the signal processing device further includes the transmitting module.

[0161] In one possible implementation, Figures 8 and 10 are two independent method flows. For example, the method flow shown in Figure 8 is a method flow executed by the signal transmission device (including a transmitting module) provided in an embodiment of the present application, and the method flow shown in Figure 10 is a method flow executed by the signal processing device (including a receiving module) provided in an embodiment of the present application. The signal transmission device and the signal processing device are two independent hardware.

[0162] In one possible implementation, Figures 8 and 10 illustrate method flows executed sequentially by the same device. For example, a radar system comprising the aforementioned transmitting module, receiving module, and processing module may first execute the method flow in Figure 8 and then the method flow in Figure 10. Another example is an on-board millimeter-wave radar comprising the aforementioned transmitting module, receiving module, and processing module may first execute the method flow in Figure 8 and then the method flow in Figure 10.

[0163] In the embodiment of the present application, the echo signal received by the signal processing device, after frequency mixing, satisfies the above formula (11) which includes the linear term of j but does not include the square term of j (or called the quadratic term), so that the phase characteristics of the high-speed moving target can change linearly in the second-dimensional signal. When the echo signal after frequency mixing is processed by FFT, there will be no spectrum peak energy broadening phenomenon, which can improve the detection probability and measurement accuracy compared with the existing scheme.

[0164] FIG12 is a flow chart of a detection method provided in an embodiment of the present application. As shown in FIG12 , the method includes:

[0165] 1201. The radar system transmits an FMCW signal.

[0166] In one possible implementation, a radar system includes the aforementioned transmitting module, receiving module, and processing module. The transmitting module in the radar system is configured to generate and transmit FMCW signals. The generation and transmission of FMCW signals by the transmitting module in the radar system can be seen in steps 801 and 802 in Figure 8. In this application, the radar system can be replaced with a detection device. An example of a radar system is a vehicle-mounted millimeter-wave radar.

[0167] 1202. The radar system receives the echo signal.

[0168] The echo signal is formed by the FMCW signal (ie, the FMCW signal transmitted by the transmitting module of the radar system) being reflected by one or more targets. In one possible implementation, a receiving module in the radar system receives the echo signal.

[0169] 1203. The radar system performs at least frequency mixing, filtering, and analog-to-digital conversion based on the echo signal to obtain a digital signal.

[0170] In one possible implementation, the receiving module in the radar system performs at least frequency mixing, filtering, and analog-to-digital conversion based on the echo signal to obtain a digital signal, as shown in step 1002 in FIG. 10 .

[0171] 1204. The radar system determines at least one of the distance and speed of one or more targets based on the digital signal.

[0172] In one possible implementation, the processing module in the radar system determines at least one of the distance and speed of one or more targets based on the digital signal, as shown in step 1003 in FIG. 10 .

[0173] The radar system can be an independent hardware or integrated into other terminals, such as cars, base stations, drones, etc.

[0174] In the embodiment of the present application, the echo signal received by the radar system after mixing processing satisfies the above formula (11) which includes the first-order term of j but does not include the square term of j (or called the second-order term), so that the phase characteristics of the high-speed moving target can change linearly in the second-dimensional signal. When the echo signal after mixing processing is processed by FFT, there will be no spectrum peak energy broadening phenomenon. Compared with the existing scheme, the detection probability and measurement accuracy can be improved.

[0175] Based on the above, a specific implementation of the aforementioned radar system is described below to further understand its structure and the process by which it determines target-related information (such as its range and speed). It should be noted that, unless otherwise specified or logically conflicting, the modules described above can be combined to form other possible radar systems based on their inherent logical relationships. The radar system described below is merely an example.

[0176] Figure 13 is a schematic diagram of the structure of a radar system provided by the present application. The radar system 1300 may include a transmitting module 1301 and a receiving module 1302, and further, may also include a processing module 1303. The transmitting module 1301 may include a VCO, a coupler, and a TX. The voltage-controlled oscillator is used to generate the above-mentioned FMCW signal. Typically, the transmitting module 1301 transmits an FMCW signal within a frame period. For example, the FMCW signal includes 256 or 512 chirp signals. The frame period refers to the duration of the transmission of a complete waveform. It should be noted that a portion of the FMCW signal is used as a local oscillator signal and is input into the mixer in the receiving module 1302 through the coupler; the other portion is transmitted through the transmitting antenna. The portion of the FMCW signal transmitted by the transmitting antenna can be referred to the relevant introduction above and will not be repeated here. Furthermore, optionally, the transmitting module 1301 may also include a PA for power amplifying the FMCW signal to be transmitted before the transmitting antenna transmits the FMCW signal.

[0177] The receiving module 1302 may include a receiving antenna (RX), an LNA, a mixer, a high-performance filter (HPF), a video-gauge (VGA), an optically coupled filter (LPF), and an analog-to-analog converter (ADC). The receiving antenna is used to receive echo signals generated by the FMCW signal transmitted by the transmitting antenna after reflection from one or more targets. For details, see the aforementioned related description. The mixer is used to mix the echo signal received by the receiving antenna with the corresponding FMCW signal (e.g., the FMCW signal output by the transmitting module to the mixer via a coupler) to obtain an intermediate frequency (IF) signal. The IF signal is filtered by the HPF, amplified by the VGA, and filtered by the LPF before being converted to a digital signal by the ADC. The processing module 1303 may sample and quantize the digital signal to form a two-dimensional array. One dimension of this two-dimensional array corresponds to the sampling point number k of the chirp signal (or the fast time dimension), and the other dimension corresponds to the chirp signal number (or the slow time dimension). A two-dimensional FFT is then performed on this two-dimensional array to obtain a range-Doppler spectrum. Based on this range-Doppler spectrum, at least one of the range and velocity of one or more targets is estimated.

[0178] Furthermore, in some embodiments, the processing module 1303 may be a circuit capable of processing signals (or data). In one possible implementation, the processing module may be a circuit capable of reading and executing instructions, such as a central processing unit (CPU), a microprocessor, a graphics processing unit (GPU) (which can be understood as a microprocessor), or a digital signal processor (DSP). In another implementation, the processing module 1303 may implement certain functions through the logical relationships of a hardware circuit, where the logical relationships of the hardware circuit are fixed or reconfigurable. For example, the processing module may be a hardware circuit implemented as an application-specific integrated circuit (ASIC) or a programmable logic device (PLD), such as a field programmable gate array (FPGA). In a reconfigurable hardware circuit, the process of the processing module loading a configuration file to implement the hardware circuit configuration can be understood as the process of the processing module loading instructions to implement the functions of some or all of the above units.

[0179] Based on the architecture and functional principles of the radar system described above, the present application can also provide a terminal device.

[0180] FIG14 is a schematic diagram of the structure of a terminal device provided in this application. The terminal device 1400 may include a radar system 1401 and a control device 1402 in any of the above embodiments. The radar system 1401 may send the associated information of the determined target (e.g., the distance and speed of the target) to the control device 1402. The control device 1402 is configured to plan a driving path based on the received associated information of the target. For example, this may be used to avoid obstacles on the driving path or to achieve autonomous driving.

[0181] The radar system 1401 may be, for example, a millimeter wave radar that utilizes radio signals to sense targets within the surrounding environment of the terminal device. In some embodiments, in addition to sensing targets, the millimeter wave radar may also be used to sense the speed and / or direction of the target.

[0182] Some or all functions of terminal device 1400 are controlled by control device 1402. Control device 1402 may include at least one processor 141 that executes instructions 1421 stored in a non-transitory computer-readable medium, such as memory 142. Furthermore, the terminal device may include a communication interface 143. For example, communication interface 143 may be used to receive target-related information from radar system 1401. Control device 1402 may also be a plurality of computing devices that control individual components or subsystems of terminal device 1400 in a distributed manner.

[0183] The processor 141 can be a circuit with signal (or data) processing capabilities. In one implementation, the processor can be a circuit with instruction reading and execution capabilities, such as a CPU, a microprocessor, a GPU, or a DSP. In another implementation, the processor can implement certain functions through the logical relationship of a hardware circuit, and the logical relationship of the hardware circuit is fixed or reconfigurable, such as a hardware circuit implemented by an ASIC or PLD, such as a field programmable gate array (FPGA). In a reconfigurable hardware circuit, the process of the processor loading a configuration document and implementing the hardware circuit configuration can be understood as the process of the processor loading instructions to implement the functions of some or all of the above units. In addition, it can also be a hardware circuit designed for artificial intelligence, which can be understood as an ASIC, such as a neural network processing unit (NPU), a tensor processing unit (TPU), a deep learning processing unit (DPU), etc. Although FIG14 functionally illustrates the processor, memory, and other elements of the control device 1402 in the same block, it should be understood by those skilled in the art that the processor and memory may actually be multiple processors or memories that are not stored in the same physical housing. For example, the memory may be a hard drive or other storage medium that is located in a housing different from that of the control device 1402.

[0184] In some embodiments, memory 142 may include instructions 1421 (e.g., program instructions) that can be read by processor 141 to execute various functions of terminal device 1400, including the functions described above. Memory 142 may also include additional instructions, including instructions for sending data to, receiving data from, interacting with, and / or controlling other systems of the terminal device (e.g., a propulsion system). In addition to instructions 1421, memory 142 may also store data, such as data detected by radar system 1401, the vehicle's location, direction, speed, and other information.

[0185] The memory may be, for example, a random access memory (RAM), a flash memory, a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a register, a hard disk, a removable hard disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from and write information to the storage medium.

[0186] It should be noted that the functional framework of the terminal device shown in FIG14 is merely an example. In other examples, the terminal device 1400 may include more, fewer, or different devices, and each device may include more, fewer, or different components. Furthermore, the devices and components shown may be combined or divided in any manner, and this application does not impose any specific limitations thereon.

[0187] For example, the terminal device may be a transportation device, which may be a vehicle (e.g., an unmanned vehicle, a smart vehicle, an electric vehicle, or a digital car), a ship, a robot, a surveying and mapping device, a drone, a smart home device (e.g., a robot vacuum cleaner, or an electrical control device), an intelligent manufacturing device (e.g., an industrial device), or an intelligent transportation device (e.g., an automated guided vehicle (AGV), an unmanned transport vehicle, or a truck). AGV refers to a transport vehicle equipped with an automatic navigation device, such as an electromagnetic or optical device, capable of traveling along a specified navigation path, and having safety protection and various transfer functions.

[0188] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. Exemplarily, the storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in a radar system. Of course, the processor and the storage medium can also exist in the radar system as separate components.

[0189] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The above-mentioned computer program product includes one or more computer programs or instructions. When the above-mentioned computer program or instruction is loaded and executed on a computer, the above-mentioned process or function of the embodiment of the present application is executed in whole or in part. The above-mentioned computer can be a general-purpose computer, a special-purpose computer, a computer network, a detection device, a user device or other programmable device. The above-mentioned computer program or instruction can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the above-mentioned computer program or instruction can be transmitted from a website, computer, server or data center to another website, computer, server or data center by wired or wireless means. The above-mentioned computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that integrates one or more available media. The above-mentioned available media can be magnetic media, such as floppy disks, hard disks, and magnetic tapes; they can also be optical media, such as digital video discs (DVDs); they can also be semiconductor media, such as solid state drives (SSDs).

[0190] Although the present application has been described with reference to specific features and embodiments thereof, it is apparent that various modifications and combinations thereof may be made without departing from the spirit and scope of the present application. Accordingly, this specification and the drawings are intended to be illustrative only of the solutions defined by the appended claims and are to be construed as covering any and all modifications, variations, combinations or equivalents within the scope of the present application.

[0191] Obviously, those skilled in the art may make various changes and modifications to the present application without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations.

Claims

1. A signal transmission method, characterized in that, Comprising: Generating a frequency-modulated continuous wave (FMCW) signal, the FMCW signal including a plurality of chirp signals; Transmit the FMCW signal, and the time interval between the j-th chirp signal and the (j - 1)-th chirp signal of the FMCW signal in time satisfies the following formula: where T′ c,j-1 is the time interval between the j-th chirp signal and the (j - 1)-th chirp signal, T j is the starting time of the j-th chirp signal, T j-1 is the starting time of the (j - 1)-th chirp signal, f c,1 is the starting frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step of the starting frequencies of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1.

2. The method according to claim 1, wherein The said 3. The method according to claim 1, wherein The 4. The method according to claim 1, wherein The said 5. The method according to any one of claims 1 to 4, characterized in that Where X = T' c,1 (f c,1 + f s ), T' c,1 is the time interval between the first chirp signal and the second chirp signal of the FMCW signal in time.

6. The method according to claim 5, characterized in that, T′ c,1 The value range of is from 1 to 100 us.

7. The method according to any one of claims 1 to 6, characterized in that, Among the plurality of chirp signals, there are different time intervals between adjacent two chirp signals.

8. The method according to any one of claims 1 to 7, characterized in that, The starting frequencies of the plurality of chirp signals have a linear change.

9. The method according to any one of claims 1 to 8, characterized in that The FMCW signal includes 256 chirp signals.

10. A signal receiving method, characterized in that, Comprising: Receive an echo signal, where the echo signal is formed by reflecting a frequency-modulated continuous-wave (FMCW) signal from one or more targets. The FMCW signal includes a plurality of chirp signals. The time interval between the j-th chirp signal and the (j - 1)-th chirp signal of the FMCW signal in time satisfies the following formula: where T′ c,j-1 is the time interval between the j-th chirp signal and the (j - 1)-th chirp signal, T j is the start time of the j-th chirp signal, T j-1 is the start time of the (j - 1)-th chirp signal, f c,1 is the start frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step of the start frequencies of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1; Based on the echo signal, determining at least one of the distance and speed of the one or more targets.

11. The method according to claim 10, wherein The X = T' c,1 (f c,1 + f s ), T' c,1 is the time interval between the first chirp signal and the second chirp signal of the FMCW signal in time.

12. The method according to claim 11, wherein T′ c,1 The value range of is from 1 to 100 us.

13. The method according to any one of claims 10 to 12, characterized in that, The determining at least one of the distance and speed of the one or more targets based on the echo signal includes: Performing mixing processing based on the FMCW signal and the echo signal to obtain a mixed echo signal after processing; Based on the mixed echo signal after processing, determining at least one of the distance and speed of the one or more targets; Among them, the expression of the echo signal after mixing processing satisfies the following formula: where, i is the imaginary unit, R is the distance to the one or more targets, j is the index of the j-th chirp signal of the FMCW signal in time, c is the speed of light, f h is the bandwidth of a single chirp signal, Tc is the effective wave transmission time of the chirp signal, f c,j is the start frequency of the j-th chirp signal, T is the sampling time interval, k is the sampling index within a single chirp signal, and v is the velocity of the one or more targets.

14. A signal transmission device, characterized in that, Comprising: A transmitting module, configured to transmit a frequency-modulated continuous wave (FMCW) signal, the FMCW signal including a plurality of chirp signals; Wherein, the time interval between the j-th chirp signal and the (j-1)-th chirp signal of the FMCW signal in time satisfies the following formula: where T′ c,j-1 is the time interval between the j-th chirp signal and the (j - 1)-th chirp signal, T j is the starting time of the j-th chirp signal, T j-1 is the starting time of the (j - 1)-th chirp signal, f c,1 is the starting frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step of the starting frequencies of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1.

15. The device according to claim 14, characterized in that, The X = T' c,1 (f c,1 + f s ), T' c,1 is the time interval between the first chirp signal and the second chirp signal of the FMCW signal in time.

16. The device according to claim 15, characterized in that, T′ c,1 has a value range of 1 to 100 us.

17. The device according to any one of claims 14 to 16, characterized in that Among the plurality of chirp signals, there are different time intervals between adjacent two chirp signals.

18. The device according to any one of claims 14 to 17, characterized in that, The starting frequencies of the plurality of chirp signals have a linear change.

19. The device according to any one of claims 14 to 18, characterized in that The FMCW signal includes 256 chirp signals.

20. A signal processing device, characterized in that, Comprising: A receiving module, configured to receive an echo signal, the echo signal being formed after the frequency-modulated continuous wave (FMCW) signal is reflected by one or more targets, The FMCW signal includes a plurality of chirp signals, and the time interval between the j-th chirp signal and the (j-1)-th chirp signal in the FMCW signal over time satisfies the following formula: where T′ c,j-1 is the time interval between the j-th chirp signal and the (j - 1)-th chirp signal, T j is the start time of the j-th chirp signal, T j-1 is the start time of the (j - 1)-th chirp signal, f c,1 is the start frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step of the start frequencies of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1; at least frequency mixing, filtering, and analog-to-digital conversion are performed on the echo signal to obtain a digital signal; A processing module, configured to determine at least one of the distance and speed of the one or more targets based on the digital signal.

21. The device according to claim 20, characterized in that, The X = T' c,1 (f c,1 + f s ), T' c,1 is the time interval between the first chirp signal and the second chirp signal of the FMCW signal in time.

22. The device according to claim 21, characterized in that, T′ c,1 The value range of is from 1 to 100 us.

23. The apparatus according to any one of claims 20 to 22, wherein The receiving module is further configured to perform mixing processing based on the FMCW signal and the echo signal to obtain a mixed echo signal after processing; The processing module is specifically configured to determine at least one of the distance and speed of the one or more targets based on the mixed echo signal after processing; Among them, the expression of the echo signal after the mixing process satisfies the following formula: where \(i\) is the imaginary unit, \(R\) is the distance to the one or more targets, \(j\) is the index of the \(j\)-th chirp signal of the FMCW signal in time, \(c\) is the speed of light, \(f\) h is the bandwidth of a single chirp signal, \(T_c\) is the effective wave transmission time of the chirp signal, \(f\) c,j is the starting frequency of the \(j\)-th chirp signal, \(T\) is the sampling time interval, \(k\) is the sampling index within a single chirp signal, and \(v\) is the velocity of the one or more targets.

24. A radar system, characterized in that, Comprising: A transmitting module, configured to transmit a frequency-modulated continuous wave (FMCW) signal, the FMCW signal including a plurality of chirp signals; Wherein, the time interval between the j-th chirp signal and the (j-1)-th chirp signal of the FMCW signal in time satisfies the following formula: Among them, T′ c,j-1 is the time interval between the j-th chirp signal and the (j - 1)-th chirp signal, T j is the starting time of the j-th chirp signal, T j-1 is the starting time of the (j - 1)-th chirp signal, f c,1 is the starting frequency of the first chirp signal of the FMCW signal in time, f s is the frequency step of the starting frequencies of two adjacent chirp signals in the FMCW signal, X is a fixed value, and j is an integer greater than 1; A receiving module, configured to receive an echo signal, the echo signal being formed after the FMCW signal is reflected by one or more targets; performing at least mixing, filtering, and analog-to-digital conversion based on the echo signal to obtain a digital signal; A processing module, configured to determine at least one of the distance and speed of the one or more targets based on the digital signal.

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