Intermediate frequency signal adaptive filtering method for frequency modulated continuous wave range radar

Abstract

The invention relates to the technical field of frequency modulated continuous wave ranging, in particular to an intermediate frequency signal adaptive filtering method for a frequency modulated continuous wave ranging radar. The method comprises the following steps: acquiring an intermediate frequency signal, and processing the intermediate frequency signal to obtain an optimal filter molecular coefficient; obtaining an optimal filter parameter according to the optimal filter molecular coefficient; and inputting the intermediate frequency signal into the optimal parameter filter for filtering operation to obtain a filtered intermediate frequency signal. According to the adaptive filtering method for the intermediate-frequency signal of the frequency-modulated continuous wave range radar, spurious frequency in the intermediate-frequency signal can be filtered out, the signal-to-noise ratio of the intermediate-frequency signal is improved, the range finding precision of the frequency-modulated continuous wave range radar is improved, the intermediate-frequency signal can be directly subjected to extraction operation after adaptive filtering, and the frequency-modulated continuous wave range radar is more accurate. Operation resources occupied by a post-stage intermediate frequency signal spectrum refinement algorithm can be reduced exponentially, and the ranging speed is improved.

Description

Technical Field

[0001] The invention relates to the technical field of frequency modulated continuous wave ranging, and in particular to an adaptive filtering method for intermediate frequency signals of a frequency modulated continuous wave ranging radar. Background Art

[0002] Frequency modulated continuous wave (FMCW) technology is a radar technology that uses continuously transmitted frequency modulated signals to achieve distance measurement. In FMCW radar systems, coherent detection is essential to extract accurate distance information from modulated signals. In FMCW systems, the waveform frequency changes continuously over time, and the transmitted signal is usually modulated continuously in a linear manner. The frequency difference between the transmitted signal and the echo signal in the FMCW radar is extracted to generate an intermediate frequency signal, and high-precision distance measurement is achieved by solving the frequency of the intermediate frequency signal.

[0003] The greater the distance measured by the FMCW ranging radar, the higher the frequency of the corresponding intermediate frequency signal, which usually ranges from a few MHz to tens of MHz. Moreover, the signal-to-noise ratio of the intermediate frequency signal will be different under different test conditions, especially in the test scenario of measuring non-cooperative targets, where the intermediate frequency signal will often be mixed with other frequency components besides the measurement signal, affecting the distance calculation accuracy and stability of the FMCW ranging radar. Therefore, the preprocessing of the intermediate frequency signal is very important in the FMCW ranging radar.

[0004] In the high-precision frequency-modulated continuous wave ranging radar of the prior art, the intermediate frequency signal needs to be filtered before the spectrum of the intermediate frequency signal is refined. However, the general low-pass, high-pass, and band-pass filters are limited by the wide-band characteristics of the intermediate frequency signal and cannot uniquely determine the optimal filter parameters, resulting in low ranging accuracy of the continuous wave ranging radar. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide an adaptive filtering method for an intermediate frequency signal of a frequency modulated continuous wave ranging radar, which can filter out spurious frequencies in the intermediate frequency signal, improve the signal-to-noise ratio of the intermediate frequency signal, and improve the ranging accuracy of the frequency modulated continuous wave ranging radar.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a method for adaptively filtering intermediate frequency signals of a frequency modulated continuous wave ranging radar, comprising:

[0007] S1, collecting intermediate frequency signals, processing the intermediate frequency signals, and obtaining optimal filter numerator coefficients;

[0008] S2. Obtaining optimal filter parameters according to the optimal filter numerator coefficients;

[0009] S3. Input the intermediate frequency signal into the optimal parameter filter for filtering to obtain a filtered intermediate frequency signal.

[0010] In one embodiment of the present invention, the processing of the intermediate frequency signal in step S1 to obtain the optimal filter numerator coefficient includes:

[0011] S11, performing windowing and Fourier transform operations on the intermediate frequency signal to extract spectrum information of the intermediate frequency signal;

[0012] S12, analyzing the frequency spectrum information to obtain optimal filter numerator coefficients.

[0013] In one embodiment of the present invention, obtaining the optimal filter parameters according to the optimal filter numerator coefficients in step S2 includes:

[0014] S21, generating a low-pass filter;

[0015] S22. According to the optimal filter numerator coefficient, convert the low-pass filter into a band-pass filter of the intermediate frequency signal to obtain the optimal filter parameters.

[0016] In one embodiment of the present invention, windowing the intermediate frequency signal in step S11 includes:

[0017] The generated Haining window sequence with a data length of N is recorded as wind(n), x(n) is multiplied by wind(n), and the sequence after the multiplication is recorded as x1(n), that is, x1(n) = x(n) · wind(n);

[0018] x(n) is the intermediate frequency signal digital sequence, N is the number of sampling points, that is, the value range of n is [1:N].

[0019] In one embodiment of the present invention, performing Fourier transform operation on the intermediate frequency signal in step S11 includes:

[0020] Perform Fourier transform on x1(n) and obtain the frequency spectrum sequence of x1(n) as X1(n). Take the first N / 2+1 data items of X1(n) as X2(m), and the value range of m is [1:N / 2+1]. Multiply each data item of X2(m) by 2 / N to obtain the one-sided complex spectrum sequence X3(m) of X1(n), that is, X3(m)=X1(1:N / 2+1)·2 / N, where 1:N / 2+1 is the first N / 2+1 data items of X1(n).

[0021] In one embodiment of the present invention, the step S12 of analyzing the spectrum information to obtain the optimal filter numerator coefficient includes:

[0022] Taking the absolute value and square operation of X3(m) yields the unilateral power spectrum sequence X4(m) of X1(m), that is, X4(m) = |X3(m)| 2 ;

[0023] Perform a maximum search operation on X4(m) to obtain the maximum value of the sequence X4(m) as X4(k), where k is the index number of the maximum value;

[0024] Perform the following formula operation on X4(k-2), X4(k-1), X4(k), X4(k+1), and X4(k+2) to obtain the optimal filter factor cor of x(n);

[0025]

[0026] Obtain the adaptive optimal filter numerator coefficient f of x(n), where f = (cor-1)·f s / N.

[0027] In one embodiment of the present invention, the low-pass filter is an IIR low-pass filter.

[0028] In one embodiment of the present invention, the step S22 converts the low-pass filter into a band-pass filter of the intermediate frequency signal according to the optimal filter numerator coefficient, and obtains the optimal filter parameters including:

[0029] Set the filter parameters z(l) and p(l), and solve the optimal filter parameters zf(l) and pf(l) of the intermediate frequency signal digital sequence x(n) through z(l), p(l) and f;

[0030] zf(l)=z(l)·cos[2π·(l-1)·f1 / f s ]+z(l)·j·sin[2π·(l-1)·f1 / f s ],

[0031] pf(l)=p(l)·cos[2π·(l-1)·f1 / f s ]+p(l)·j·sin[2π·(l-1)·f1 / f s ],

[0032] Among them, the value range of l is [1:3], f s is the sampling frequency, and j represents a complex number.

[0033] In one embodiment of the present invention, the step S3 of inputting the intermediate frequency signal into the optimal parameter filter for filtering to obtain the filtered intermediate frequency signal comprises:

[0034] Perform filtering operation on the intermediate frequency signal digital sequence x(n), and the x_s(n) and y_s(n) sequences are used to store intermediate operation results. Formula A, Formula B, Formula C, Formula D, and Formula E are used to calculate in sequence to obtain the sequence y(n) after filtering the intermediate frequency signal digital sequence x(n);

[0035] Formula A:

[0036] y(s)=[zf(1)*x(s)+zf(2)*x_s(1)+zf(3)*x_s(2)]-[pf(2)*y_s(1)+pf(3)+y_s(2)],

[0037] Formula B: x_s(2)=x_s(1),

[0038] Formula C: x_s(1)=x(s),

[0039] Formula D: y_s(2)=y_s(1),

[0040] Formula E: y_s(1)=y(s).

[0041] The present invention also provides an adaptive filtering device for intermediate frequency signals of a frequency modulated continuous wave ranging radar, comprising:

[0042] The optimal filter numerator coefficient solving module is used to collect the intermediate frequency signal, process the intermediate frequency signal, and obtain the optimal filter numerator coefficient;

[0043] An optimal filter parameter solving module, used for obtaining the optimal filter parameters according to the optimal filter numerator coefficients;

[0044] The filtering module is used to input the intermediate frequency signal into the optimal parameter filter for filtering to obtain a filtered intermediate frequency signal.

[0045] As described above, the present invention provides an adaptive filtering method for intermediate frequency signals of a frequency modulated continuous wave ranging radar, which has the following features:

[0046] Beneficial effects:

[0047] (1) The adaptive filtering method for intermediate frequency signals of frequency modulated continuous wave ranging radar of the present invention can filter out spurious frequencies in the intermediate frequency signals, improve the signal-to-noise ratio of the intermediate frequency signals, and improve the ranging accuracy of the frequency modulated continuous wave ranging radar.

[0048] (2) The intermediate frequency signal of the intermediate frequency signal adaptive filtering method for frequency modulated continuous wave ranging radar of the present invention can be directly extracted after adaptive filtering, which can reduce the computing resources occupied by the subsequent intermediate frequency signal spectrum refinement algorithm by multiples and improve the ranging speed.

[0049] (3) The adaptive filtering method for intermediate frequency signals of frequency modulated continuous wave ranging radar of the present invention obtains the optimal filter numerator coefficient by pre-analyzing the frequency information of the intermediate frequency signal, and then solves the optimal filter parameters, which can filter out the frequency components outside ±0.1 MHz of the intermediate frequency signal and improve the signal-to-noise ratio of the intermediate frequency signal. After the intermediate frequency signal is processed, the negative frequency domain part has no spectral components, which is convenient for subsequent extraction processing and can greatly reduce the computing resources of the subsequent spectrum refinement algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A principle block diagram of a method for adaptive filtering of intermediate frequency signals of a frequency modulated continuous wave ranging radar provided in an embodiment of the present application.

[0051] Figure 2 A filtering flow chart of a method for adaptively filtering intermediate frequency signals of a frequency modulated continuous wave ranging radar provided in an embodiment of the present application.

[0052] Figure 3 A flowchart of a method for adaptive filtering of intermediate frequency signals of a frequency modulated continuous wave ranging radar provided in an embodiment of the present application.

[0053] Figure 4 A flowchart of step S1 of a method for adaptively filtering intermediate frequency signals of a frequency modulated continuous wave ranging radar provided in an embodiment of the present application.

[0054] Figure 5 A flowchart of step S2 of a method for adaptively filtering intermediate frequency signals of a frequency modulated continuous wave ranging radar provided in an embodiment of the present application. DETAILED DESCRIPTION

[0055] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0056] It should be noted that the illustrations provided in the following embodiments are only used to illustrate the basic concept of the present invention in a schematic manner, and thus the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0057] Terms such as first or second can be used to describe various components, but these components are not limited by the above terms. The above terms are used to distinguish one component from another component, for example, without departing from the scope of the concept according to the present disclosure, a first component can be referred to as a second component, and similarly, a second component can be referred to as a first component.

[0058] In addition, "connected / coupled" means that one component is directly electrically coupled to another component or is indirectly electrically coupled through another component. The singular form may include the plural form unless explicitly stated in the sentence. In addition, "include / comprise" or "includes / comprises" used in this specification indicates that one or more components, steps, operations, and elements exist or have been added. The specific structural or functional descriptions of the examples of the implementation of the concepts disclosed in this specification are only illustrated to describe the examples of the implementation of the concepts, and the examples of the implementation of the concepts can be implemented in various forms, but these descriptions are not limited to the examples of the implementation described in this specification.

[0059] According to the concept, various modifications and changes can be applied to the examples of the embodiments, so that the examples of the embodiments will be illustrated in the drawings and described in the specification. However, the examples of the embodiments according to the concept are not limited to the specific embodiments, but include all changes, equivalents or replacements included in the spirit and technical scope of the present disclosure.

[0060] It should be understood that when an element is described as being "coupled" or "connected" to another element, the element may be directly coupled or directly connected to the other element, or may be coupled or connected to the other element through a third element. Conversely, it should be understood that when an element is referred to as being "directly coupled to" or "directly coupled to" another element, no other element is placed between them. Other expressions describing the relationship between components (i.e., "between" and "directly between" or "adjacent to" and "directly adjacent to") need to be interpreted in the same manner.

[0061] The terms used in this specification are only used to describe specific examples of the embodiments and are not intended to limit the present disclosure. If there is no clear opposite meaning in the context, the singular form may include the plural form. In this specification, it should be understood that the term "including" or "having" indicates the presence of the features, quantities, steps, operations, components, parts or combinations thereof described in the specification, but the possibility of the presence or addition of one or more other features, quantities, steps, operations, components, parts or combinations thereof cannot be precluded.

[0062] If there is no contrary definition, all terms (including technical terms or scientific terms) used herein have the same meaning as those generally understood by ordinary technicians in the field. If the terms defined in the commonly used dictionary are not clearly defined in this specification, they should be interpreted as having the same meaning as in the context of the relevant technology, and not interpreted as ideal or overly formal meanings.

[0063] Descriptions of well-known components and processing techniques may be omitted so as not to unnecessarily obscure the embodiments of the disclosure.

[0064] Throughout the specification, the same reference numerals refer to the same elements. Thus, even if a reference numeral is not mentioned or described with reference to one figure, it may be mentioned or described with reference to another figure. Furthermore, even if a reference numeral is not shown in one figure, it may be mentioned or described with reference to another figure.

[0065] In addition, the logic level of the signal may be different or opposite to the described logic level. For example, a signal described as having a logic "high" level may alternatively have a logic "low" level, and a signal described as having a logic "low" level may alternatively have a logic "high" level.

[0066] The following will describe the various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present disclosure, many technical details are provided in order to enable the reader to better understand the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can be implemented.

[0067] See also Figure 1 , Figure 3 , Figure 1 A principle block diagram of a method for adaptive filtering of intermediate frequency signals of a frequency modulated continuous wave ranging radar provided in an embodiment of the present application. Figure 3 A flowchart of a method for adaptively filtering intermediate frequency signals of a frequency modulated continuous wave ranging radar provided in an embodiment of the present application. The present invention provides a method for adaptively filtering intermediate frequency signals of a frequency modulated continuous wave ranging radar, comprising:

[0068] Step S1, collecting an intermediate frequency signal, processing the intermediate frequency signal, and obtaining an optimal filter numerator coefficient.

[0069] Step S2: Obtain optimal filter parameters according to the optimal filter numerator coefficients.

[0070] Step S3: input the intermediate frequency signal into the optimal parameter filter for filtering to obtain a filtered intermediate frequency signal.

[0071] See also Figure 4 , Figure 4 The flowchart of step S1 of a method for adaptive filtering of intermediate frequency signals of frequency modulated continuous wave ranging radar provided in the embodiment of the present application. In step S1, the intermediate frequency signal is processed to obtain the optimal filter numerator coefficient, which includes:

[0072] Step S11, performing windowing and Fourier transform operations on the intermediate frequency signal to extract spectrum information of the intermediate frequency signal.

[0073] Specifically, the windowing of the intermediate frequency signal in step S11 includes: generating a Henning window sequence with a data length of N, recorded as wind(n), multiplying x(n) and wind(n), and the sequence after the multiplication is recorded as x1(n), that is, x1(n)=x(n)·wind(n); x(n) is the digital sequence of the intermediate frequency signal, N is the number of sampling points, that is, the value range of n is [1:N].

[0074] Specifically, the Fourier transform operation on the intermediate frequency signal in step S11 includes: performing Fourier transform on x1(n) to obtain the frequency spectrum sequence of x1(n) as X1(n), taking the first N / 2+1 items of data of X1(n) as X2(m), the value range of m is [1:N / 2+1], and multiplying each item of data of X2(m) by 2 / N to obtain the unilateral complex spectrum sequence X3(m) of X1(n), that is, X3(m)=X1(1:N / 2+1)·2 / N, where 1:N / 2+1 is the first N / 2+1 items of data of X1(n).

[0075] Step S12: Analyze the spectrum information to obtain the optimal filter numerator coefficient.

[0076] Specifically, the spectrum information is analyzed in step S12 to obtain the optimal filter numerator coefficient, which includes:

[0077] Taking the absolute value and square operation of X3(m) yields the unilateral power spectrum sequence X4(m) of X1(m), that is, X4(m) = |X3(m)| 2 ; Perform a maximum value search operation on X4(m) to obtain the maximum value of the sequence X4(m) as X4(k), where k is the index number of the maximum value; perform the following formula operation on X4(k-2), X4(k-1), X4(k), X4(k+1), and X4(k+2) to obtain the optimal filter factor cor of x(n);

[0078]

[0079] Obtain the adaptive optimal filter numerator coefficient f of x(n), where f = (cor-1)·fs / N.

[0080] See also Figure 5 , Figure 5 The flowchart of step S2 of a method for adaptive filtering of intermediate frequency signals of frequency modulated continuous wave ranging radar provided in an embodiment of the present application. In step S2, obtaining the optimal filter parameters according to the optimal filter numerator coefficients includes:

[0081] Step S21: Generate a low-pass filter.

[0082] Step S22: According to the optimal filter numerator coefficient, convert the low-pass filter into a band-pass filter of the intermediate frequency signal to obtain the optimal filter parameters.

[0083] Specifically, in step S22, according to the optimal filter numerator coefficient, converting the low-pass filter into a band-pass filter of the intermediate frequency signal to obtain the optimal filter parameters includes:

[0084] Set the filter parameters z(l) and p(l), and solve the optimal filter parameters zf(l) and pf(l) of the intermediate frequency signal digital sequence x(n) through z(l), p(l) and f;

[0085] zf(l)=z(l)·cos[2π·(l-1)·f1 / f s ]+z(l)·j·sin[2π·(l-1)·f1 / f s ],

[0086] pf(l)=p(l)·cos[2π·(l-1)·f1 / f s ]+p(l)·j·sin[2π·(l-1)·f1 / f s ],

[0087] Among them, the value range of l is [1:3], f s is the sampling frequency, and j represents a complex number.

[0088] For details, please refer to Figure 2 , Figure 2 A filtering flow chart of a method for adaptive filtering of intermediate frequency signals of a frequency modulated continuous wave ranging radar provided in an embodiment of the present application. The step S3 of inputting the intermediate frequency signal into the optimal parameter filter for filtering operation to obtain the filtered intermediate frequency signal includes:

[0089] Perform filtering operation on the intermediate frequency signal digital sequence x(n), and the x_s(n) and y_s(n) sequences are used to store intermediate operation results. Formula A, Formula B, Formula C, Formula D, and Formula E are used to calculate in sequence to obtain the sequence y(n) after filtering the intermediate frequency signal digital sequence x(n);

[0090] Formula A:

[0091] y(s)=[zf(1)*x(s)+zf(2)*x_s(1)+zf(3)*x_s(2)]-[pf(2)*y_s(1)+pf(3)+y_s(2)],

[0092] Formula B: x_s(2)=x_s(1),

[0093] Formula C: x_s(1)=x(s),

[0094] Formula D: y_s(2)=y_s(1),

[0095] Formula E: y_s(1)=y(s).

[0096] The adaptive filtering method for intermediate frequency signals of frequency modulated continuous wave ranging radar of the present invention obtains the optimal filter numerator coefficient by pre-analyzing the frequency information of the intermediate frequency signal, and then solves the optimal filter parameters, which can filter out the frequency components outside ±0.1MHz of the intermediate frequency signal and improve the signal-to-noise ratio of the intermediate frequency signal. After the intermediate frequency signal is processed, the negative frequency domain part has no spectrum components, which is convenient for subsequent extraction processing and can greatly reduce the computing resources of the subsequent spectrum refinement algorithm.

[0097] In one embodiment of the present invention, see Figure 1 , Figure 2 , assuming that the intermediate frequency signal digital sequence acquired by the analog-to-digital converter is x(n) and the sampling frequency is f s , the number of sampling points is N, that is, the value range of n is [1:N]. The following are the steps of the adaptive bandpass filtering method for the sequence x(n).

[0098] The generated Haining window sequence with a data length of N is recorded as wind(n), x(n) is multiplied by wind(n), and the sequence after the multiplication is recorded as x1(n).

[0099] That is, x1(n) = x(n)·wind(n);

[0100] Perform Fourier transform on x1(n) to obtain the spectrum sequence of x1(n) as X1(n), take the first N / 2+1 items of data of X1(n) as X2(m), the value range of m is [1:N / 2+1], multiply each item of data of X2(m) by 2 / N to obtain the single-sided complex spectrum sequence X3(m) of X1(n), that is, X3(m) = X1(1:N / 2+1)·2 / N, where 1:N / 2+1 represents the first N / 2+1 items of data of X1(n);

[0101] Taking the absolute value and square operation of X3(m) yields the unilateral power spectrum sequence X4(m) of X1(m), that is, X4(m) = |X3(m)| 2 ;

[0102] Perform a maximum search operation on X4(m) to obtain the maximum value of the sequence X4(m) as X4(k), where k is the index number of the maximum value;

[0103] Perform the following calculation on X4(k-2), X4(k-1), X4(k), X4(k+1), and X4(k+2) to obtain the optimal filter factor cor of x(n);

[0104]

[0105] Obtain the optimal numerator coefficient f of the adaptive filter of x(n), where f = (cor-1)·f s / N;

[0106] The IIR low-pass filter coefficients are generated by MATLAB software. The filter parameters set in this patent are: stopband cutoff frequency 0.2MHz, stopband attenuation 30dB, filter order 2nd order, and z(1)=0.03155580, z(2)=-0.06310164, z(3)=0.03155580, p(1)=1, p(2)=-1.99560157, p(3)=0.99561153;

[0107] The optimal adaptive filter parameters zf(l) and pf(l) of x(n) are solved by z(l), p(l) and f, where the value range of l is [1:3], and j in the following formula represents a complex number;

[0108] zf(l)=z(l)·cos[2π·(l-1)·f1 / f s ]+z(l)·j·sin[2π·(l-1)·f1 / f s ],

[0109] pf(l)=p(l)·cos[2π·(l-1)·f1 / f s]+p(l)·j·sin[2π·(l-1)·f1 / f s ],

[0110] Perform filtering operation on x(n), declare x_s(n) and y_s(n) sequences to store intermediate operation results, and use formula A, formula B, formula C, formula D, and formula E to calculate the value of the filter. Figure 2 Calculate and solve to obtain the filtered sequence y(n) of x(n);

[0111] Formula A:

[0112] y(s)=[zf(1)*x(s)+zf(2)*x_s(1)+zf(3)*x_s(2)]-[pf(2)*y_s(1)+pf(3)+y_s(2)],

[0113] Formula B: x_s(2)=x_s(1),

[0114] Formula C: x_s(1)=x(s),

[0115] Formula D: y_s(2)=y_s(1),

[0116] Formula E: y_s(1)=y(s).

[0117] The present invention also proposes an electronic device, which includes a processor and a memory, wherein the memory stores program instructions, and the processor runs the program instructions to implement the above-mentioned adaptive filtering method for intermediate frequency signals of frequency-modulated continuous wave ranging radar. The processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components; the memory may include a random access memory (RAM), and may also include a non-volatile memory, such as at least one disk memory. The memory can also be an internal memory of the random access memory (RAM) type, and the processor and memory can be integrated into one or more independent circuits or hardware, such as an application-specific integrated circuit (ASIC). It should be noted that the computer program in the above-mentioned memory can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, an electronic device, or a network device, etc.) to perform all or part of the steps of the methods of various embodiments of the present invention.

[0118] The present invention also proposes a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the above-mentioned adaptive filtering method for intermediate frequency signals of frequency modulated continuous wave ranging radar. The computer-readable storage medium can be an electronic medium, a magnetic medium, an optical medium, an electromagnetic medium, an infrared medium or a semiconductor system or a propagation medium. The computer-readable storage medium can also include a semiconductor or solid-state memory, a magnetic tape, a removable computer disk, a random access memory (RAM), a read-only memory (ROM), a hard disk and an optical disk. The optical disk can include a compact disk-read only memory (CD-ROM), a compact disk-read / write (CD-RW) and a DVD.

[0119] In summary, the method for adaptive filtering of intermediate frequency signals of frequency modulated continuous wave ranging radar of the present invention can filter out spurious frequencies in the intermediate frequency signals, improve the signal-to-noise ratio of the intermediate frequency signals, and improve the ranging accuracy of the frequency modulated continuous wave ranging radar. The intermediate frequency signals of the method for adaptive filtering of intermediate frequency signals of frequency modulated continuous wave ranging radar of the present invention can be directly extracted after adaptive filtering, which can reduce the computing resources occupied by the spectrum refinement algorithm of the subsequent intermediate frequency signals by multiples and improve the ranging speed.

[0120] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for adaptive filtering of intermediate frequency signals of frequency modulated continuous wave ranging radar, characterized in that: include: S1, collecting intermediate frequency signals, processing the intermediate frequency signals, and obtaining optimal filter numerator coefficients; S2. Obtaining optimal filter parameters according to the optimal filter numerator coefficients; S3. Input the intermediate frequency signal into the optimal parameter filter for filtering to obtain a filtered intermediate frequency signal.

2. The method for adaptive filtering of intermediate frequency signals of frequency modulated continuous wave ranging radar according to claim 1, characterized in that: The processing of the intermediate frequency signal in step S1 to obtain the optimal filter numerator coefficient includes: S11, performing windowing and Fourier transform operations on the intermediate frequency signal to extract spectrum information of the intermediate frequency signal; S12, analyzing the frequency spectrum information to obtain optimal filter numerator coefficients.

3. The method for adaptive filtering of intermediate frequency signals of frequency modulated continuous wave ranging radar according to claim 1, characterized in that: Obtaining the optimal filter parameters according to the optimal filter numerator coefficient in step S2 includes: S21, generating a low-pass filter; S22. According to the optimal filter numerator coefficient, convert the low-pass filter into a band-pass filter of the intermediate frequency signal to obtain the optimal filter parameters.

4. The method for adaptive filtering of intermediate frequency signals of FMCW ranging radar according to claim 2, characterized in that: The windowing of the intermediate frequency signal in step S11 includes: The generated Haining window sequence with a data length of N is recorded as wind(n), x(n) is multiplied by wind(n), and the sequence after the multiplication is recorded as x1(n), that is, x1(n) = x(n) · wind(n); x(n) is the intermediate frequency signal digital sequence, N is the number of sampling points, that is, the value range of n is [1:N].

5. The method for adaptive filtering of intermediate frequency signals of FMCW ranging radar according to claim 4, characterized in that: The Fourier transform operation on the intermediate frequency signal in step S11 includes: Perform Fourier transform on x1(n) and obtain the frequency spectrum sequence of x1(n) as X1(n). Take the first N / 2+1 data items of X1(n) as X2(m), and the value range of m is [1:N / 2+1]. Multiply each data item of X2(m) by 2 / N to obtain the one-sided complex spectrum sequence X3(m) of X1(n), that is, X3(m)=X1(1:N / 2+1)·2 / N, where 1:N / 2+1 is the first N / 2+1 data items of X1(n).

6. The method for adaptive filtering of intermediate frequency signals of FMCW ranging radar according to claim 5, characterized in that: The analysis of the spectrum information in step S12 to obtain the optimal filter numerator coefficients includes: Taking the absolute value and square operation of X3(m) yields the unilateral power spectrum sequence X4(m) of X1(m), that is, X4(m) = |X3(m)| 2 ; Perform a maximum search operation on X4(m) to obtain the maximum value of the sequence X4(m) as X4(k), where k is the index number of the maximum value; Perform the following formula operation on X4(k-2), X4(k-1), X4(k), X4(k+1), and X4(k+2) to obtain the optimal filter factor cor of x(n); Obtain the adaptive optimal filter numerator coefficient f of x(n), where f = (cor-1)·f s / N.

7. The method for adaptive filtering of intermediate frequency signals of FMCW ranging radar according to claim 3, characterized in that: The low-pass filter is an IIR low-pass filter.

8. The method for adaptive filtering of intermediate frequency signals of FMCW ranging radar according to claim 7, characterized in that: The step S22 converts the low-pass filter into a band-pass filter of the intermediate frequency signal according to the optimal filter numerator coefficient, and obtains the optimal filter parameters, including: Set the filter parameters z(l) and p(l), and solve the optimal filter parameters zf(l) and pf(l) of the intermediate frequency signal digital sequence x(n) through z(l), p(l) and f; zf(l)=z(l)·cos[2π·(l-1)·f1 / f s ]+z(l)·j·sin[2π·(l-1)·f1 / f s ], pf(l)=p(l)·cos[2π·(l-1)·f1 / f s ]+p(l)·j·sin[2π·(l-1)·f1 / f s ], Among them, the value range of l is [1:3], f s is the sampling frequency, and j represents a complex number.

9. The method for adaptive filtering of intermediate frequency signals of FMCW ranging radar according to claim 1, characterized in that: The step S3 of inputting the intermediate frequency signal into the optimal parameter filter for filtering to obtain the filtered intermediate frequency signal comprises: Perform filtering operation on the intermediate frequency signal digital sequence x(n), and the x_s(n) and y_s(n) sequences are used to store intermediate operation results. Formula A, Formula B, Formula C, Formula D, and Formula E are used to calculate in sequence to obtain the sequence y(n) after filtering the intermediate frequency signal digital sequence x(n); Formula A: y(s)=[zf(1)*x(s)+zf(2)*x_s(1)+zf(3)*x_s(2)]-[pf(2)*y_s(1)+pf(3)+y_s(2)], Formula B: x_s(2)=x_s(1), Formula C: x_s(1)=x(s), Formula D: y_s(2)=y_s(1), Formula E: y_s(1)=y(s).

10. An adaptive filtering device for intermediate frequency signals of frequency modulated continuous wave ranging radar, characterized in that: include: The optimal filter numerator coefficient solving module is used to collect the intermediate frequency signal, process the intermediate frequency signal, and obtain the optimal filter numerator coefficient; An optimal filter parameter solving module, used for obtaining the optimal filter parameters according to the optimal filter numerator coefficients; The filtering module is used to input the intermediate frequency signal into the optimal parameter filter for filtering to obtain a filtered intermediate frequency signal.

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