Surface target frequency modulation continuous wave distance measurement and speed measurement method and system based on trapezoidal wave

Abstract

The invention discloses a surface target frequency modulation continuous wave distance measurement and speed measurement method and system based on trapezoidal waves, and the method specifically comprises the steps: firstly, transmitting a three-period trapezoidal wave signal through a radar, receiving an echo signal, carrying out the frequency mixing of the echo signal and a transmitted signal, obtaining a difference frequency signal, and obtaining a center frequency estimation value through a gravity center method; then linear frequency modulation Z transformation is carried out to obtain refined signal frequency spectrums; taking a peak value according to a second periodic signal, namely a single-frequency signal frequency spectrum to obtain a frequency value, and calculating to obtain a speed estimation value; and finally, according to the first and third periodic signal spectrums, using a spectrum multi-feature joint estimation method to obtain an accurate distance estimation value. According to the method, the speed measurement error can be greatly reduced under the condition that the distance error is almost unchanged, the effect is remarkable in the short distance, the method is simple, the implementation cost is low, and the method is suitable for distance measurement and speed measurement of a surface target in the foresight state of the frequency-modulated continuous wave radar.

Description

Technical Field

[0001] This invention relates to the field of radar detection technology, and in particular to a method and system for ranging and measuring the velocity of a surface target using frequency-modulated continuous wave based on trapezoidal waves. Background Technology

[0002] Ranging and velocity measurement of surface targets using frequency-modulated continuous wave (FM-CHW) radar is crucial. For example, in planetary lander operations, auxiliary measurement methods based on radar signals are needed to ensure successful landing. For FM-CHW radar-based ranging and velocity measurement, triangular wave signals are typically used. These signals exhibit linear frequency modulation characteristics with positive and negative periods. The difference frequency between the positive and negative periods can be extracted using a single Fourier transform, allowing for simultaneous measurement of both distance and velocity.

[0003] However, in the face-to-face target problem, the broadening of the difference frequency signal spectrum leads to inaccurate center frequency estimation, which in turn affects the accuracy of ranging and velocity measurement algorithms. While methods such as the centroid method and joint estimation of multiple spectral features exist, their velocity measurement errors remain significant. When the radar is in forward-looking mode, the platform's motion direction and the antenna's main beam direction are essentially aligned, and the Doppler frequency variation of the observation area relative to the radar platform almost disappears. In this case, if only velocity is measured, the spectrum will not broaden further, and the area target problem is equivalent to the point target problem. Using a frequency-modulated continuous wave signal based on trapezoidal waves can significantly reduce velocity measurement errors while maintaining almost constant range error, with particularly noticeable effects at close range.

[0004] Therefore, by using trapezoidal wave signals and employing an algorithm based on joint estimation of multiple spectral features, the measurement error of velocity can be significantly reduced, and the accuracy of frequency modulated continuous wave radar in ranging and velocity measurement of surface targets in forward-looking mode can be improved. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for ranging and velocity measurement of surface targets based on trapezoidal waves using frequency-modulated continuous waves, thereby reducing velocity measurement errors and improving the accuracy of ranging and velocity measurement of surface targets in forward-looking mode.

[0006] The technical solution to achieve the purpose of this invention is: a method for ranging and velocity measurement of surface targets using frequency-modulated continuous wave based on trapezoidal waves, comprising the following steps:

[0007] Step 1: The radar transmits a three-cycle trapezoidal wave signal and receives the echo signal;

[0008] Step 2: Mix the echo signal with the transmitted signal to obtain the difference frequency signal;

[0009] Step 3: Divide the difference frequency signal into periods, and use the centroid method to obtain the estimated center frequency values ​​of the difference frequency signal for each of the three periods.

[0010] Step 4: Take the center frequency estimates of the positive and negative modulated frequency-modulated signals and the single-frequency signal as the midpoints respectively, determine the initial frequency and the end frequency according to the refinement factor and the sampling frequency, and perform linear frequency modulation Z-transform to obtain the refined signal spectrum.

[0011] Step 5: Obtain the frequency value by taking the peak value of the spectrum of the second period signal, i.e., the single-frequency signal, and calculate the speed estimate.

[0012] Step 6: Based on the spectrum of the first and third period signals, use the multi-feature joint estimation method to obtain the final distance estimate.

[0013] Furthermore, the trapezoidal wave signal mentioned in step 1 is specifically as follows:

[0014] The radar signal uses trapezoidal wave modulation with a modulation bandwidth of [missing information]. The modulation period is The center frequency of the signal is The three cycles have the same duration, all of which are Set echo delay to ,in The initial distance between the target and the radar. Indicates the radial velocity between the radar and the target. It is the speed of light, and the frequency is [frequency value missing]. .

[0015] Furthermore, the radar in step 1 transmits a three-cycle trapezoidal wave signal and receives the echo signal, as detailed below:

[0016] The expression for the transmitted signal is:

[0017] (1)

[0018] in, Indicates the amplitude of the transmitted signal. Represents the imaginary unit;

[0019] The received echo signal is represented as:

[0020] (2)

[0021] in, The time delay between the received signal and the transmitted signal.

[0022] Furthermore, the step 2, which involves mixing the echo signal with the transmitted signal to obtain the difference frequency signal, is detailed as follows:

[0023] The difference frequency signal is represented as:

[0024] (3)

[0025] in, This indicates losses during the transmission process.

[0026] Furthermore, in step 3, the centroid method is used to obtain the estimated center frequency of the difference frequency signal for the three periods using the spectrum of the difference frequency signal. The calculation formula is as follows:

[0027] (4)

[0028] in, This represents the sampling point number corresponding to the peak value of the difference frequency spectrum. The number of points taken on both sides of the peak of the difference frequency spectrum during estimation. For the first time in the modulation period The difference frequency signal spectrum amplitude value corresponding to each sampling point.

[0029] Furthermore, the expression for the linear frequency modulated Z-transform described in step 4 is:

[0030] (5)

[0031] Where A is the complex starting point and W is the interval between adjacent sampling points. To refine the scope, The starting frequency is calculated using the following formula:

[0032] (6)

[0034] Furthermore, the formula for calculating the speed estimate mentioned in step 5 is as follows:

[0035] (7)

[0036] in, The frequency value is obtained by taking the peak value of the spectrum of the second period signal, i.e., the single-frequency signal.

[0037] Furthermore, the calculation formula for the joint estimation method of spectral multi-features described in step 6 is as follows:

[0038] (8)

[0039] in, It consists of six characteristic frequency points. It is calculated from system parameters. The required parameter is expressed as follows:

[0040] (9)

[0041] The characteristic frequency points include the maximum and minimum frequencies of the positive and negative frequency modulation periods, as well as the center frequency of the positive and negative frequency modulation periods. Indicates pitch angle, Indicates beamwidth. Indicates altitude.

[0042] A trapezoidal wave-based frequency-modulated continuous wave ranging and velocity measurement system for surface targets is disclosed. This system implements the aforementioned trapezoidal wave-based frequency-modulated continuous wave ranging and velocity measurement method for surface targets. The system includes a radar module, a mixing module, a signal segmentation module, a linear frequency-modulated Z-transform module, a velocity estimation module, and a range estimation module.

[0043] The radar module transmits a three-cycle trapezoidal wave signal and receives the echo signal.

[0044] The mixer module uses the echo signal and the transmitted signal to mix and obtain the difference frequency signal;

[0045] The signal segmentation module divides the difference frequency signal according to the period, and uses the centroid method to obtain the estimated center frequency of the difference frequency signal for the three periods of the spectrum.

[0046] The linear frequency modulation Z-transform module takes the center frequency estimates of the positive and negative modulation frequency modulation signals and the single frequency signal as the midpoints, determines the initial frequency and the end frequency according to the refinement factor and the sampling frequency, and performs linear frequency modulation Z-transform to obtain the refined signal spectrum.

[0047] The velocity estimation module obtains the frequency value by taking the peak value of the spectrum of the second-cycle signal, i.e., the single-frequency signal, and then calculates the velocity estimate.

[0048] The distance estimation module uses a multi-feature joint estimation method based on the spectrum of the first and third period signals to obtain the final distance estimate.

[0049] An electronic device includes a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the aforementioned trapezoidal wave-based surface target frequency-modulated continuous wave ranging and velocity measurement method.

[0050] Compared with the prior art, the present invention has the following significant advantages: (1) It uses a frequency-modulated continuous wave signal based on trapezoidal wave, which can significantly reduce the speed measurement error while keeping the distance error almost unchanged, and the effect is significant at close range; (2) The method is simple, the implementation cost is low, and it is suitable for frequency-modulated continuous wave radar to perform range and speed measurement of surface targets in forward-looking state. Attached Figure Description

[0051] Figure 1This is a flowchart illustrating a method for measuring the distance and velocity of a surface target using frequency-modulated continuous wave based on trapezoidal waves, according to the present invention.

[0052] Figure 2 This is a schematic diagram of the frequency of the trapezoidal wave signal changing with time in this invention. Detailed Implementation

[0053] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0054] In one specific embodiment, the present invention provides a method for ranging and velocity measurement of surface targets using frequency-modulated continuous wave based on trapezoidal waves, such as... Figure 1 As shown, it includes the following steps:

[0055] Step 1: The radar transmits a three-cycle trapezoidal wave signal and receives the echo signal;

[0056] like Figure 2 As shown, the radar signal uses trapezoidal wave modulation with a modulation bandwidth of [missing information]. The modulation period is The center frequency of the signal is The three cycles have the same duration, all of which are Set echo delay to ,in The initial distance between the target and the radar. Indicates the radial velocity between the radar and the target. It is the speed of light, and the frequency is [frequency value missing]. ;

[0057] The expression for the transmitted signal is:

[0058] (1)

[0059] in, Indicates the amplitude of the transmitted signal. Represents the imaginary unit;

[0060] The received echo signal is represented as:

[0061] (2)

[0062] in, The time delay between the received signal and the transmitted signal.

[0063] Step 2: Mix the echo signal with the transmitted signal to obtain the difference frequency signal, as follows:

[0064] The difference frequency signal is represented as:

[0065] (3)

[0066] in, This indicates losses during the transmission process.

[0067] Step 3: Divide the difference frequency signal according to its period. Apply the centroid method to the spectrum of the difference frequency signal for each of the three periods to obtain the estimated center frequency values ​​of the difference frequency signal for the three periods. The calculation formula is as follows:

[0068] (4)

[0069] in, This represents the sampling point number corresponding to the peak value of the difference frequency spectrum. The number of points taken on both sides of the peak of the difference frequency spectrum during estimation. For the first time in the modulation period The difference frequency signal spectrum amplitude value corresponding to each sampling point.

[0070] Step 4: Take the center frequency estimates of the positive and negative modulated frequency-modulated signals and the single-frequency signal as the midpoints respectively, determine the initial frequency and the end frequency according to the refinement factor and the sampling frequency, and perform linear frequency modulation Z-transform to obtain the refined signal spectrum.

[0071] The expression for the linear frequency modulated Z-transform is:

[0072] (5)

[0073] Where A is the complex starting point and W is the interval between adjacent sampling points. To refine the scope, The starting frequency is calculated using the following formula:

[0074] (6)

[0075] Step 5: Obtain the frequency value by taking the peak value of the spectrum of the second period signal, i.e., the single-frequency signal, and calculate the speed estimate.

[0076] The formula for calculating the speed estimate is:

[0077] (7)

[0078] in, The frequency value is obtained by taking the peak value of the spectrum of the second period signal, i.e., the single-frequency signal.

[0079] Step 6: Based on the spectrum of the first and third period signals, use the multi-feature joint estimation method to obtain an accurate distance estimate.

[0080] The calculation formula for the multi-feature joint estimation method of the spectrum is as follows:

[0081] (8)

[0082] in, It consists of six characteristic frequency points. It is calculated from system parameters. The required parameter is expressed as follows:

[0083] (9)

[0084] The characteristic frequency points include the maximum and minimum frequencies of the positive and negative frequency modulation periods, as well as the center frequency of the positive and negative frequency modulation periods. Indicates pitch angle, Indicates beamwidth. Indicates altitude.

[0085] In one specific embodiment, the present invention also provides a trapezoidal wave-based frequency-modulated continuous wave ranging and velocity measurement system for surface targets. This system is used to implement the aforementioned trapezoidal wave-based frequency-modulated continuous wave ranging and velocity measurement method for surface targets. The system includes a radar module, a mixing module, a signal segmentation module, a linear frequency-modulated Z-transform module, a velocity estimation module, and a range estimation module.

[0086] The radar module transmits a three-cycle trapezoidal wave signal and receives the echo signal.

[0087] The mixer module uses the echo signal and the transmitted signal to mix and obtain the difference frequency signal;

[0088] The signal segmentation module divides the difference frequency signal according to the period, and uses the centroid method to obtain the estimated center frequency of the difference frequency signal for the three periods of the spectrum.

[0089] The linear frequency modulation Z-transform module takes the center frequency estimates of the positive and negative modulation frequency modulation signals and the single frequency signal as the midpoints, determines the initial frequency and the end frequency according to the refinement factor and the sampling frequency, and performs linear frequency modulation Z-transform to obtain the refined signal spectrum.

[0090] The velocity estimation module obtains the frequency value by taking the peak value of the spectrum of the second-cycle signal, i.e., the single-frequency signal, and then calculates the velocity estimate.

[0091] The distance estimation module uses a multi-feature joint estimation method based on the spectrum of the first and third period signals to obtain the final distance estimate.

[0092] In one specific embodiment, the present invention also provides an electronic device, including: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the described trapezoidal wave-based surface target frequency-modulated continuous wave ranging and velocity measurement method.

[0093] For example, the computer program may be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the electronic device.

[0094] The electronic device may be a desktop computer, laptop, handheld computer, or smart tablet, etc. The electronic device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the above components are merely examples of electronic devices and do not constitute a limitation on the electronic device. It may include more or fewer components than described above, or combine certain components, or different components. For example, the electronic device may also include input / output devices, network access devices, buses, etc.

[0095] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the electronic device, connecting all parts of the electronic device via various interfaces and lines.

[0096] The memory can be used to store the computer programs and / or modules. The processor implements various functions of the electronic device by running or executing the computer programs and / or modules stored in the memory and by calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the mobile phone (such as audio data, phonebook, etc.). In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0097] Wherein, if the modules / units integrated in the electronic device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0098] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0099] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for ranging and velocity measurement of surface targets using frequency-modulated continuous wave based on trapezoidal waves, characterized in that, Includes the following steps: Step 1: The radar transmits a three-cycle trapezoidal wave signal and receives the echo signal; Step 2: Mix the echo signal with the transmitted signal to obtain the difference frequency signal; Step 3: Divide the difference frequency signal into periods, and use the centroid method to obtain the estimated center frequency values ​​of the difference frequency signal for each of the three periods. Step 4: Take the center frequency estimates of the positive and negative modulated frequency-modulated signals and the single-frequency signal as the midpoints respectively, determine the initial frequency and the end frequency according to the refinement factor and the sampling frequency, and perform linear frequency modulation Z-transform to obtain the refined signal spectrum. Step 5: Obtain the frequency value by taking the peak value of the spectrum of the second period signal, i.e., the single-frequency signal, and calculate the speed estimate. Step 6: Based on the spectrum of the first and third period signals, use the multi-feature joint estimation method to obtain the final distance estimate.

2. The method for ranging and velocity measurement of a surface target based on trapezoidal waves according to claim 1, characterized in that, The trapezoidal wave signal mentioned in step 1 is as follows: The radar signal uses trapezoidal wave modulation with a modulation bandwidth of [missing information]. The modulation period is The center frequency of the signal is The three cycles have the same duration, all of which are ; Set echo delay to ,in The initial distance between the target and the radar. Indicates the radial velocity between the radar and the target. It is the speed of light, and the frequency is [frequency value missing]. .

3. The method for ranging and velocity measurement of a surface target based on trapezoidal waves according to claim 2, characterized in that, The radar transmitting a three-cycle trapezoidal wave signal and receiving the echo signal as described in step 1 is as follows: The expression for the transmitted signal is: （1） in, Indicates the amplitude of the transmitted signal. Represents the imaginary unit; The received echo signal is represented as: （2） in, The time delay between the received signal and the transmitted signal.

4. The method for ranging and velocity measurement of a surface target based on trapezoidal waves according to claim 3, characterized in that, Step 2, which involves mixing the echo signal with the transmitted signal to obtain the difference frequency signal, is detailed below: The difference frequency signal is represented as: （3） in, This indicates losses during the transmission process.

5. The method for ranging and velocity measurement of a surface target based on trapezoidal waves according to claim 4, characterized in that, In step 3, the centroid method is used to obtain the estimated center frequency of the difference frequency signal for the three periods. The calculation formula is as follows: （4） in, This represents the sampling point number corresponding to the peak value of the difference frequency spectrum. The number of points taken on both sides of the peak of the difference frequency spectrum during estimation. For the first time in the modulation period The difference frequency signal spectrum amplitude value corresponding to each sampling point.

6. The method for ranging and velocity measurement of a surface target based on trapezoidal waves according to claim 5, characterized in that, The expression for the linear frequency modulated Z-transform described in step 4 is: （5） Where A is the complex starting point and W is the interval between adjacent sampling points. To refine the scope, The starting frequency is calculated using the following formula: （6）。 7. The method for ranging and velocity measurement of a surface target based on trapezoidal waves according to claim 6, characterized in that, The formula for calculating the speed estimate mentioned in step 5 is as follows: （7） in, The frequency value is obtained by taking the peak value of the spectrum of the second period signal, i.e., the single-frequency signal.

8. The method for ranging and velocity measurement of a surface target based on trapezoidal waves according to claim 7, characterized in that, The calculation formula for the multi-feature joint estimation method of the spectrum described in step 6 is as follows: （8） in, It consists of six characteristic frequency points. It is calculated from system parameters. The required parameter is expressed as follows: （9） The characteristic frequency points include the maximum and minimum frequencies of the positive and negative frequency modulation periods, as well as the center frequency of the positive and negative frequency modulation periods. Indicates pitch angle, Indicates beamwidth. Indicates altitude.

9. A surface target frequency-modulated continuous wave ranging and velocity measurement system based on trapezoidal waves, characterized in that, This system is used to implement the trapezoidal wave-based frequency-modulated continuous wave ranging and velocity measurement method for surface targets as described in any one of claims 1 to 8. The system includes a radar module, a mixing module, a signal segmentation module, a linear frequency-modulated Z-transform module, a velocity estimation module, and a range estimation module. The radar module transmits a three-cycle trapezoidal wave signal and receives the echo signal. The mixer module uses the echo signal and the transmitted signal to mix and obtain the difference frequency signal; The signal segmentation module divides the difference frequency signal according to the period, and uses the centroid method to obtain the estimated center frequency of the difference frequency signal for the three periods of the spectrum. The linear frequency modulation Z-transform module takes the center frequency estimates of the positive and negative modulation frequency modulation signals and the single frequency signal as the midpoints, determines the initial frequency and the end frequency according to the refinement factor and the sampling frequency, and performs linear frequency modulation Z-transform to obtain the refined signal spectrum. The velocity estimation module obtains the frequency value by taking the peak value of the spectrum of the second-cycle signal, i.e., the single-frequency signal, and then calculates the velocity estimate. The distance estimation module uses a multi-feature joint estimation method based on the spectrum of the first and third period signals to obtain the final distance estimate.

10. An electronic device, characterized in that, include: The system includes a memory and a processor, which are interconnected. The memory stores computer instructions, and the processor executes the computer instructions to perform the surface target frequency-modulated continuous wave ranging and velocity measurement method based on trapezoidal waves as described in any one of claims 1 to 8.

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