A radar, a radar channel separation method and apparatus

Abstract

This invention discloses a radar, a radar channel separation method, and an apparatus. The radar includes: N radar chips connected in a cascaded manner, each radar chip having m transmitters and n receivers, where N ≥ 2 and N, m, and n are all positive integers; the m transmitters and n receivers on each radar chip share a single linear frequency modulated (LFM) signal generator; there is a frequency offset between the center frequencies of the LFM continuous waves generated by the LFM signal generators of any two radar chips; the transmitter's transmitted signal is modulated from the LFM continuous wave using a preset multiplexing modulation scheme, and the receiver uses the LFM continuous wave as a de-LFM signal to perform channel separation on the received mixed echo signal. By implementing beat frequency division multiplexing (BFDM) technology on multiple cascaded chips and combining it with existing single multiplexing technology, the limitations of single multiplexing technology are overcome, improving the radar's channel separation capability and enhancing its performance.

Description

Technical Field

[0001] This invention relates to the field of radar design technology, and in particular to a radar, a radar channel separation method and apparatus. Background Technology

[0002] Today, there are increasingly higher demands for 4D imaging radar to provide richer information. This means that resolution in all dimensions (range, velocity, azimuth, and elevation) must be maximized. Range and velocity resolution can be achieved by increasing transmission frequency bandwidth and transmission time. Azimuth and elevation resolution can be achieved by increasing virtual channels, thereby increasing the size of the virtual antenna aperture.

[0003] However, increasing antenna aperture and radar size are contradictory. MIMO technology is one of the saviors, as it can increase antenna aperture while keeping radar size within a certain range. The core issue in introducing MIMO is achieving receiver channel separation, meaning that each receiving antenna (channel) at the receiver needs to separate the mixed signals from several transmitting antennas to achieve virtual aperture synthesis.

[0004] Common techniques for achieving channel separation in Multiple-Input Multiple-Output (MIMO) include Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), and Frequency Division Multiplexing (FDM); a common FDM technique is Doppler Division Multiplexing (DDM). Most commonly used radar chips support TDM, DDM, and CDM waveform settings; however, using any single multiplexing method has certain limitations. Summary of the Invention

[0005] This invention provides a radar, a radar channel separation method, and an apparatus to address the limitations of existing single multiplexing methods. It implements beat frequency division multiplexing modulation technology on multiple cascaded chips and combines it with existing single multiplexing technology to overcome the limitations of single multiplexing, improve the radar's channel separation capability, and enhance its performance.

[0006] According to one aspect of the present invention, a radar is provided, the radar comprising: N radar chips connected in a cascaded manner, each radar chip having m transmitters and n receivers, where N≥2 and N, m, and n are all positive integers; the m transmitters and n receivers on each radar chip share a linear frequency modulated signal generator; and there is a frequency offset between the center frequencies of the frequency-modulated continuous waves generated by the linear frequency modulated signal generators of any two radar chips.

[0007] The transmitter's transmitted signal is obtained by modulating the frequency-modulated continuous wave through a preset multiplexing modulation method. The receiver uses the frequency-modulated continuous wave as a de-linearized frequency modulation signal to perform channel separation on the received mixed echo signal. The receiver receives transmitted signals from different radar chips with different beat frequencies.

[0008] According to another aspect of the present invention, a channel separation method for radar is provided, applied to a radar chip in a radar; the method includes:

[0009] The radar chip receives the mixed echo signal through a receiver and obtains the radar's configuration parameters. The mixed echo signal includes echo signals obtained by m transmitters on each radar chip transmitting signals to the target. A two-dimensional Fourier transform is performed on the mixed echo signal to obtain the range Doppler map of the mixed echo signal.

[0010] Extract all peaks from the distance Doppler image and treat each peak as an echo signal of one channel;

[0011] The echo signals of each channel are grouped according to the preset multiplexing modulation mode of the radar chip to obtain the echo signal corresponding to each transmitter group.

[0012] For the echo signal of each channel in each transmitter group, the transmitter corresponding to each echo signal is determined based on the distance of the peak value corresponding to each echo signal in the distance Doppler graph and the configuration parameters.

[0013] According to another aspect of the present invention, a channel separation device for radar is provided, applied to a radar chip in a radar, the device comprising:

[0014] The signal receiving module is used to receive the mixed echo signal through the receiver on the radar chip and obtain the configuration parameters of the radar; the mixed echo signal includes: the echo signal obtained by each of the m transmitters on each radar chip transmitting signals to the target.

[0015] The processing module is used to perform a two-dimensional Fourier transform on the mixed echo signal to obtain the range Doppler map of the mixed echo signal;

[0016] An extraction module is used to extract all peaks in the distance Doppler image and treat each peak as an echo signal of one channel.

[0017] The grouping module is used to group the echo signals of each channel according to the preset multiplexing modulation mode of the radar chip, so as to obtain the echo signal corresponding to each transmitter group.

[0018] The determination module is used to determine the transmitter corresponding to each echo signal based on the distance of the peak value corresponding to each echo signal in the distance Doppler graph and the configuration parameters for each channel echo signal in each transmitter group.

[0019] The radar provided by this invention employs N radar chips connected in a cascaded manner. Each radar chip has m transmitters and n receivers, where N ≥ 2 and N, m, and n are all positive integers. The m transmitters and n receivers on each radar chip share a single linear frequency modulated (LFM) signal generator. There is a frequency offset between the center frequencies of the LFM continuous waves generated by the LFM signal generators of any two radar chips. The transmitted signal from the transmitter is modulated by a preset multiplexing modulation method using an LFM continuous wave. The receiver uses an LFM continuous wave as a de-linear frequency modulated signal to perform channel separation on the received mixed echo signal. The beat frequencies of the transmitted signals received by the receiver from different radar chips are different. By implementing beat frequency division multiplexing technology on multiple cascaded chips and combining it with existing single multiplexing technology, the limitations of single multiplexing technology can be overcome, improving the radar's channel separation capability and enhancing its performance. It should be understood that the content described in this section is not intended to identify key or important features of the embodiments of the invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of beat frequency division multiplexing modulation technology for traditional radars based on dual transmitters and dual receivers;

[0022] Figure 2 This is a time-frequency relationship diagram of transmitted / received signals in a traditional BFDM-based radar.

[0023] Figure 3 It is a beat frequency spectrum diagram of the receiver of a traditional radar with two transmitters, with channel separation in orthogonal and non-orthogonal structures;

[0024] Figure 4 This is a schematic diagram of the transmitter and receiver structure of a traditional radar chip;

[0025] Figure 5 This is a schematic diagram of the structure of a radar provided in Embodiment 1 of the present invention;

[0026] Figure 6 This is a schematic diagram of a radar system that implements BFDM on two cascaded radar chips.

[0027] Figure 7 This is a schematic diagram showing the location of the beat frequency signal corresponding to the echo signal received by the quadrature receiver on the radar chip;

[0028] Figure 8 This is a schematic diagram showing the location of the beat frequency signal corresponding to the echo signal received by the non-orthogonal receiver on the radar chip;

[0029] Figure 9 This is a flowchart of a radar channel separation method provided in Embodiment 2 of the present invention;

[0030] Figure 10 This is the time-frequency diagram of the hybrid echo signal received by the receiver in BFDM+TDM mode;

[0031] Figure 11 This is the time-frequency diagram of the hybrid echo signal received by the receiver in BFDM+CDM mode;

[0032] Figure 12 This is the time-frequency diagram of the mixed echo signal received by the receiver in BFDM+DDM mode;

[0033] Figure 13 This is a schematic diagram of the structure of a radar channel separation device provided in Embodiment 3 of the present invention. Detailed Implementation

[0034] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0035] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products or devices.

[0036] For most radar chip devices, the number of transmit and receive channels is finite and fixed. Compared to redesigning the radar chip, cascading multiple existing radar chips to increase the number of virtual channels is a more direct and easier solution. Due to the use of multiple chips, effectively separating the transmit channels presents a greater challenge in MIMO waveform design. Generally, increasing the number of transmit channels increases the virtual antenna aperture, but this also affects the performance of some system parameters—a trade-off.

[0037] Each of the aforementioned multiplexing methods has its limitations. For example, Time Division Multiplexing (TDM) not only reduces the unambiguous velocity but also, due to the coupling between velocity and angle, leads to incorrect velocity estimation, affecting the accuracy of angle estimation. Code Division Multiplexing (CDM), regardless of whether adjustments are made in the slow or fast time dimension, increases the noise floor amplitude with the number of transmit channels, resulting in a decrease in the signal-to-noise ratio (SNR). While Doppler Frequency Division Multiplexing (DDM) can separate transmit channels in the Doppler dimension, it is not always the optimal choice when multiple targets are present in the scene. This is because this technology subdivides the entire Doppler range into narrower subdomains, increasing the likelihood that multiple targets at different velocities fall into the same Doppler frequency band, thus increasing the complexity and difficulty of resolving velocity ambiguity.

[0038] In addition to the above, common frequency division multiplexing modulation techniques also include beating frequency division multiplexing (BFDM). The basic principle of channel separation based on beating frequency division multiplexing modulation is usually: there is a frequency offset f between the transmitted signals of m transmitters. Δ Then, a receiver receives a mixed echo signal corresponding to the transmitted signals from the transmission channels of these m transmitters in its receiving channel. After the receiver performs delinear frequency modulation on the received mixed echo signal, the m echo signals from different transmission channels can be separated because there is also a frequency offset f between these m echo signals. ΔTherefore, echo signals from m different transmission channels can be distinguished from the mixed echo signals received by the receiver, thereby realizing channel separation based on beat frequency division multiplexing modulation technology (BFDM).

[0039] Figure 1 This is a schematic diagram of beat frequency division multiplexing modulation technology in traditional radar based on dual transmitters and dual receivers. For example... Figure 1 As shown, two transmitters, Tx1 and Tx2, each have their own linear frequency modulation (LFM) generators to produce frequency modulated continuous wave (FMCW) signals, and the two LFM generators are synchronized. The center frequency offset between the two LFM generators is f. Δ ,

[0040]

[0041] Where, N TX f is the number of transmitters with different center frequencies. b,max This is the maximum beat frequency. Whether the receiver is orthogonal or non-orthogonal, f b,max Both can be determined by the sampling frequency f s Decide.

[0042] Figure 2 This is a time-frequency relationship diagram of transmitted / received signals in a traditional BFDM-based radar. For example... Figure 2 As shown, for receiver Rx1, there is a detection target O at a distance R, and there is a frequency offset f between the center frequencies of the transmitted signals of transmitters Tx1 and Tx2. Δ Then receiver Rx1 will receive echo signals from transmitters Tx1 and Tx2, and there is a frequency offset f between the beat frequencies of these two echo signals. Δ The beat frequencies are as follows:

[0043]

[0044]

[0045] Where R is the distance between the receiver Rx1 and the target, BW is the radar bandwidth, and T... PRI This refers to the radar's signal transmission cycle.

[0046] The receiver can be orthogonal or non-orthogonal, and the beat frequency spectrum of the receiver is determined by whether the receiver is orthogonal. Figure 3 This is a beat frequency spectrum diagram of the receiver of a traditional radar with two transmitters, showing channel separation in orthogonal and non-orthogonal configurations. Figure 3The first figure is the beat frequency spectrum of the channel separation of the non-orthogonal receiver Rx1, and the second figure is the beat frequency spectrum of the channel separation of the orthogonal receiver Rx1.

[0047] In summary, the implementation of traditional BFDM requires the following two conditions: Condition 1: Each transmitter needs an independent signal generator that can be set with different center frequencies, and the signal generators of different transmitters must be time-synchronized. Condition 2: All receivers use the same chirped signal as the delinearization frequency modulation signal.

[0048] Figure 4 This is a schematic diagram of the transmitter and receiver structure of a traditional radar chip. (Example) Figure 4 As shown, the waveform design of commonly used radar chips generally does not allocate an independent linear frequency modulation (LFM) signal generator for each transmitter. Instead, three transmitters share a single LFM signal generator, which fails to meet condition 1 and thus makes it impossible to implement BFDM on a single radar chip.

[0049] However, since each radar chip has its own transmitter, receiver, and signal generator, it is possible to implement BFDM on a multi-chip cascaded system. Therefore, to address the above problems, this invention proposes a radar design scheme that implements beat frequency division multiplexing (BFDM) technology on multiple cascaded chips and combines it with existing single multiplexing technologies, such as TDM, CDM, and DDM. This overcomes the limitations of single multiplexing technologies, improves the radar's channel separation capability, and enhances the radar's performance indicators.

[0050] Example 1

[0051] Figure 5 This is a schematic diagram of the structure of a radar provided in Embodiment 1 of the present invention. Figure 5 As shown, in this embodiment, the radar uses N radar chips connected in a cascaded manner. Each radar chip has m transmitters and n receivers, where N ≥ 2. Figure 5 (where N=3); N, m, and n are all positive integers (in Figure 5 In the configuration (m=3, n=4), each radar chip has m transmitters and n receivers sharing a single linear frequency modulated (LFM) signal generator; there is a frequency offset between the center frequencies of the LFM continuous waves generated by the LFM signal generators of any two radar chips; the transmitter's transmitted signal is modulated by the LFM continuous wave through a preset multiplexing modulation method, and the receiver uses the LFM continuous wave as the de-linear frequency modulated signal to perform channel separation on the received mixed echo signal; the beat frequencies of the transmitted signals received by the receiver from different radar chips are different.

[0052] Specifically, Figure 5The diagram shows a radar system with three cascaded radar chips A, B, and C, where N=3. Each radar chip uses a common configuration of 3Tx4Rx, meaning each chip has three transmitters and four receivers. Radar chip A has three transmitters (Tx1, Tx2, and Tx3) and four receivers (Rx1, Rx2, Rx3, and Rx4); radar chip B has three transmitters (Tx4, ​​Tx5, and Tx6) and four receivers (Rx5, Rx6, Rx7, and Rx8); and radar chip C has three transmitters (Tx7, Tx8, and Tx9) and four receivers (Rx9, Rx10, Rx11, and Rx12). By using similar system clock sources and timing controllers, N radar chips are synchronized in time, phase, and frequency. Each radar chip can support preset multiplexing modulation methods, such as Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), and the common Doppler Division Multiplexing (DDM). That is, each transmitter has its own dedicated and programmable ON-OFF switch (which can be used for TDM modulation) and a built-in phase shifter (which can be used for CDM and DDM modulation).

[0053] Understandably, the number N of cascaded radar chips can be expanded to more as needed. The number of transmitters m and receivers n on each radar chip can be set according to actual requirements. Figure 5 This is merely an example and is not intended to limit the number of radar chips N, the number of transmitters m, or the number of receivers n.

[0054] like Figure 5 As shown, each radar chip is equipped with an independent linear frequency modulated (LFM) signal generator. Therefore, the m transmitters and n receivers on each radar chip can share a single LFM signal generator. Specifically, transmitters Tx1, Tx2, and Tx3, and receivers Rx1, Rx2, Rx3, and Rx4 on radar chip A share the first LFM signal generator, whose center frequency is f. c The transmitters Tx4, Tx5, and Tx6 on radar chip B, as well as the receivers Rx5, Rx6, Rx7, and Rx8, share a second linear frequency modulated (LFM) signal generator. The center frequency of this second LFM signal generator is f. c +f Δ1The transmitters Tx7, Tx8, and Tx9 on radar chip C, as well as the receivers Rx9, Rx10, Rx11, and Rx12, share a third linear frequency modulated (LFM) signal generator. The center frequency of this third LFM signal generator is f. c +f Δ2 ; where f Δ2 ≠f Δ1 .

[0055] Therefore, there is a frequency offset between the center frequencies of the frequency-modulated continuous waves generated by the linear frequency modulation (FM) signal generators of any two radar chips. Specifically, the center frequency f of the FM continuous wave generated by the FM signal generator of radar chip A is... c The center frequency f of the frequency-modulated continuous wave generated by the linear frequency-modulated signal generator of radar chip B is... c +f Δ1 There is a frequency offset f Δ1 The center frequency f of the frequency-modulated continuous wave generated by the linear frequency-modulated signal generator of radar chip A is... c The center frequency f of the frequency-modulated continuous wave generated by the linear frequency-modulated signal generator of radar chip C is... c +f Δ2 There is a frequency offset f Δ2 The center frequency f of the frequency-modulated continuous wave generated by the linear frequency-modulated signal generator of radar chip B is... c +f Δ1 The center frequency f of the frequency-modulated continuous wave generated by the linear frequency-modulated signal generator of radar chip C is... c +f Δ2 There is a frequency offset f Δ2 -f Δ1 Because the transmitter signals of different radar chips are obtained by generating frequency-modulated continuous waves from linear frequency modulation signal generators and then using a preset multiplexing modulation method, the center frequencies of the transmitted signals of different radar chips are different, resulting in frequency offset.

[0056] Each receiver on each radar chip can receive transmitted signals from each transmitter on different radar chips. For each receiver, a frequency-modulated continuous wave (FM-MCW) is used as the de-linearized FM signal to separate the channels of the received mixed echo signals. Therefore, the beat frequencies of the transmitted signals received by the receivers from different radar chips are different. The frequency offset between the beat frequencies of the echo signals received by the receivers can be used to determine which radar chip's transmission channel the echo signal corresponds to. This achieves channel separation using beat frequency division multiplexing (BFDM) modulation technology on the cascaded radar chips. Simultaneously, each radar chip is modulated using a preset multiplexing modulation method. Therefore, the echo signal corresponding to the transmitter from the same radar chip can be further identified using a preset multiplexing modulation method, thus achieving channel separation using preset multiplexing modulation technology on each independent radar chip within the cascaded radar chips.

[0057] The radar provided by this invention employs N radar chips connected in a cascaded manner. Each radar chip has m transmitters and n receivers, where m and n are both positive integers. The m transmitters and n receivers on each radar chip share a single linear frequency modulated (LFM) signal generator. There is a frequency offset between the center frequencies of the LFM continuous waves generated by the LFM signal generators of any two radar chips. The transmitted signal from the transmitter is modulated by a preset multiplexing modulation method using an LFM continuous wave. The receiver uses an LFM continuous wave as a de-LFM signal to perform channel separation on the received mixed echo signal. The beat frequencies of the transmitted signals received by the receiver from different radar chips are different. By implementing beat frequency division multiplexing technology on multiple cascaded chips and combining it with existing single multiplexing technology, the limitations of single multiplexing technology can be overcome, improving the radar's channel separation capability and enhancing its performance. In an optional embodiment, each of the radar chips is configured with the same preset multiplexing modulation mode, which may include: code division multiplexing modulation mode, time division multiplexing modulation mode, or Doppler frequency division multiplexing modulation mode.

[0058] By configuring each radar chip to the same preset multiplexing modulation mode, such as code division multiplexing modulation mode (CDM), time division multiplexing modulation mode (TDM), or frequency division multiplexing modulation mode (DDM), channel separation methods such as BFDM+CDM, BFDM+TDM, and BFDM+DDM can be realized.

[0059] In one optional embodiment, the transmitters on the N radar chips constitute M transmitter groups, each transmitter group including one transmitter on each radar chip, and each transmitter belongs to only one transmitter group.

[0060] Specifically, Figure 6 This is a schematic diagram of a radar system implementing BFDM on two cascaded radar chips. (Example) Figure 6 As shown, radar chip A and radar chip B are cascaded. The transmitters Tx1, Tx2, and Tx3 on radar chip A, as well as the receivers Rx1, Rx2, Rx3, and Rx4, share the first linear frequency modulated (LFM) signal generator. The center frequency of the first LFM signal generator is f. c The transmitters Tx4, Tx5, and Tx6 on radar chip B, as well as the receivers Rx5, Rx6, Rx7, and Rx8, share a second linear frequency modulated (LFM) signal generator. The center frequency of this second LFM signal generator is f. c +f Δ Because any receiver on each radar chip can receive transmitted signals from each transmitter on different radar chips. For example, receiver Rx1 on radar chip A can receive echo signals corresponding to the transmitted signals from transmitters Tx1, Tx2, and Tx3 on radar chip A, as well as echo signals corresponding to the transmitted signals from transmitters Tx4, Tx5, and Tx6 on radar chip B. By processing the echo signals received by receiver Rx1, echo signals with different beat frequencies can be identified, thereby distinguishing the echo signals corresponding to the transmitted signals from transmitters on radar chip A and radar chip B.

[0061] However, it is still necessary to further determine which transmitter from radar chip A or radar chip B corresponds to the echo signal. Therefore, the transmitters of the N cascaded radar chips are grouped. Based on the grouping principle that each transmitter group includes one transmitter from each radar chip, and each transmitter belongs to only one transmitter group, the transmitters on the N radar chips can be grouped into M transmitter groups. Each transmitter group includes N transmitters from different radar chips. In the radar chip's preset multiplexing modulation mode, the transmitted signals corresponding to the transmitters in each transmitter group have the same preset multiplexing modulation parameters. Within each transmission group, the transmitter corresponding to the echo signal can be determined based on the frequency offset between the beat frequencies of the echo signals.

[0062] For example, for such Figure 6 The radar shown here, with two cascaded radar chips, can have its transmitter grouping configuration information as shown in Table 1. It is understood that other grouping methods can also be configured as long as the above grouping principles are met.

[0063] Table 1

[0064] Transmitter group Radar chip A Radar chip B Transmitter Group 1 Tx1 Tx4 Transmitter Group 2 Tx2 Tx5 Transmitter Group 3 Tx3 Tx6

[0065] In another alternative embodiment, the frequency offset is one-Nth of the sampling frequency of the radar.

[0066] Specifically, in order to ensure the accuracy of the echo signal channel separation, it is also necessary to further ensure that the received echo signal does not undergo spectral aliasing. Therefore, it is necessary to set the frequency offset between the center frequencies of the frequency-modulated continuous waves generated by the linear frequency-modulated signal generators of any two radar chips.

[0067] For example, such as Figure 6 The radar shown has two cascaded radar chips. The receiver on radar chip A can receive echo signals from transmitters on both radar chip A and radar chip B. The receiver on radar chip A uses a delinearized frequency modulation signal with a center frequency of fc. Then, the beat frequency of the echo signal received by any receiver on chip A corresponding to the transmitted signal emitted by the transmitter to a target at a distance R is:

[0068]

[0069] Similarly, the receiver on radar chip B can receive echo signals from the transmitters on radar chip A and radar chip B. The center frequency of the delinearized frequency modulation signal used by the receiver on radar chip B is f. c +f Δ Then, the beat frequency of the echo signal received by any receiver on radar chip B corresponding to the transmitted signal emitted by the transmitter to the target at a distance of R is:

[0070]

[0071] Among them, f Δ Here, R is the frequency offset, R is the distance between the receiver and the target, BW is the radar bandwidth, and T is the frequency offset. PRI This refers to the radar's signal transmission cycle.

[0072] Assuming the maximum detection range is R max The corresponding maximum beat frequency is Based on the receiver's structure (orthogonal or non-orthogonal), the frequency offset f can be estimated. Δ The setting amount.

[0073] In one example, for such Figure 6 The radar shown has two cascaded radar chips. Assume that radar chip A has two transmitters. Figure 7 This is a schematic diagram showing the location of the beat frequency signal corresponding to the echo signal received by the quadrature receiver on the radar chip. If the receiver is a quadrature receiver, the location of the beat frequency signal is as follows: Figure 7The first image shows the constraints that need to be met:

[0074] For the receiver on radar chip A, the delinearized frequency modulation signal associated with the transmitter on radar chip B must fall within the aliasing region, i.e., it must meet the following requirements. f s f is the signal sampling frequency of the radar, which is the same as the signal sampling frequency of the transmitter on radar chip A and the transmitter on radar chip B. s .

[0075] Similarly, to avoid spectral overlap, it is necessary to satisfy... and -f s +f Δ +f b,max If ≤0, then the maximum value of the beat frequency. therefore, For the quadrature receiver on radar chip B, the position of the beat frequency signal is as follows: Figure 7 The second image shows the frequency shift f Δ Similarly satisfied

[0076] Therefore, for the quadrature receiver on radar chip A with two transmitters, it is easy to deduce by analogy that... and N represents the number of radar chips, which is also the number of transmitters in each transmitter group.

[0077] In another example, for such Figure 6 The radar shown has two cascaded radar chips. Assume that radar chip A has two transmitters. Figure 8 This is a schematic diagram showing the location of the beat frequency signal corresponding to the echo signal received by a non-orthogonal receiver on a radar chip. If the receiver is a non-orthogonal receiver, the location of the beat frequency signal is as follows: Figure 8 The first image shows the constraints that need to be met:

[0078] For the receiver on radar chip A, the delinearized frequency modulation signal associated with the transmitter on radar chip B must fall within the aliasing region, i.e., it must meet the following requirements.

[0079] Similarly, to avoid spectral overlap, it is necessary to satisfy... and -f s +f Δ +f b,max If ≤0, then the maximum value of the beat frequency. therefore, For the non-orthogonal receiver on radar chip B, the position of the beat frequency signal is as follows: Figure 8 The second image shows the frequency shift f Δ Similarly satisfied

[0080] Therefore, for a non-orthogonal receiver on radar chip A with two transmitters, it is easy to deduce by analogy that... and N represents the number of radar chips, which is also the number of transmitters in each transmitter group.

[0081] In summary, the following conclusions can be drawn: configuring the frequency offset to one-Nth of the radar's sampling frequency can prevent spectral aliasing in the received echo signal, further ensuring the accuracy of echo signal channel separation.

[0082] Example 2

[0083] Figure 9 This is a flowchart of a radar channel separation method provided in Embodiment 2 of the present invention. This embodiment is applicable to the case of channel separation of mixed echo signals received by radar. The method can be executed by a radar channel separation device, which can be implemented in hardware and / or software and can be configured in the radar. Figure 9 As shown, the method includes:

[0084] S210. Receive the mixed echo signal through the receiver on the radar chip and obtain the radar configuration parameters; the mixed echo signal includes the echo signal obtained by each of the m transmitters on each radar chip transmitting signals to the target.

[0085] The mixed echo signal is a composite signal of the echo signals received by the receiver from the transmitters. Radar configuration parameters refer to pre-configured radar-related parameters, which may include: the radar's signal transmission period, bandwidth, transmitter grouping method, frequency offset between the center frequencies of the frequency-modulated continuous waves generated by the linear frequency-modulated signal generators of any two radar chips, and receiver structure, etc.

[0086] Specifically, for a radar with n cascaded radar chips, each of which includes m transmitters and n receivers, if all the transmitters on the cascaded radar chips transmit signals to the target, then each receiver on each radar chip can receive the mixed echo signal corresponding to each transmitted signal.

[0087] S220. Perform a two-dimensional Fourier transform on the mixed echo signal to obtain the range Doppler map of the mixed echo signal.

[0088] Specifically, after receiving the mixed echo signal, each receiver on each radar chip can perform a two-dimensional range-Doppler Fourier transform on the mixed echo signal to obtain a range-Doppler map composed of the range dimension and the Doppler dimension.

[0089] S230. Extract all peaks in the distance Doppler image and treat each peak as an echo signal of one channel.

[0090] Specifically, each peak in the range Doppler image represents the echo signal of one channel. Therefore, by extracting all the peaks in the range Doppler image and treating each peak as an echo signal of one channel, the echo signals of all channels in the mixed echo signal can be obtained.

[0091] S240. Group the echo signals of each channel according to the preset multiplexing modulation mode of the radar chip to obtain the echo signal corresponding to each transmitter group.

[0092] Specifically, when the radar chip is in a preset multiplexing modulation mode, the common signal characteristics of the echo signals corresponding to each transmitter group are related to the preset multiplexing modulation method. Therefore, the echo signals of each channel can be grouped according to the preset multiplexing modulation mode of the radar chip to obtain the echo signal corresponding to each transmitter group.

[0093] S250. For the echo signals of each channel in each transmitter group, determine the transmitter corresponding to each echo signal based on the distance of the peak value of each echo signal in the distance-Doppler graph and the configuration parameters.

[0094] Specifically, after obtaining the echo signal corresponding to each transmitter group, since there is a frequency offset between the center frequencies of the transmitters within each transmitter group, the frequency offset between multiple echo signals corresponding to each transmitter group can be determined based on the distance of the peak value of the echo signal in the distance-Doppler map and the configuration parameters. The frequency offset between the center frequencies of the frequency-modulated continuous waves generated by the linear frequency-modulated signal generators of any two configured radar chips is then compared to determine the transmitter corresponding to each echo signal.

[0095] The technical solution of this invention involves receiving a mixed echo signal through a receiver on a radar chip and obtaining the radar's configuration parameters. The mixed echo signal includes echo signals obtained from m transmitters on each radar chip transmitting signals to the target. A two-dimensional Fourier transform is performed on the mixed echo signal to obtain a range Doppler map. All peak values ​​in the range Doppler map are extracted, and each peak value is used as an echo signal for one channel. The echo signals of each channel are grouped according to the preset multiplexing modulation mode of the radar chip to obtain the echo signal corresponding to each transmitter group. For the echo signals of each channel in each transmitter group, the transmitter corresponding to each echo signal is determined based on the distance of the peak value corresponding to each echo signal in the range Doppler map and the configuration parameters. By implementing beat frequency division multiplexing modulation (BFDM) technology on multiple cascaded chips, combined with the preset multiplexing modulation technology (TDM, DDM, or CDM) of each radar chip, channel separation can be achieved, overcoming the limitations of a single multiplexing technology and improving the radar's channel separation performance.

[0096] Optionally, determining the transmitter corresponding to each echo signal based on the distance of the peak value corresponding to the echo signal in the distance-Doppler map and the configuration parameters includes:

[0097] The frequency offset between each echo signal is determined based on the distance corresponding to each echo signal and the configuration parameters;

[0098] The transmitter corresponding to each echo signal is determined based on the frequency offset.

[0099] Specifically, for the echo signals of each channel in each transmitter group, the frequency offset between each echo signal is determined based on the distance and configuration parameters corresponding to each echo signal. Based on the frequency offset between each echo signal and the frequency offset between the transmitted signals of the transmitters included in the transmitter group, the transmitter corresponding to the echo signal of each channel in the transmitter group can be determined.

[0100] The method for determining the frequency offset between echo signals based on the distance corresponding to the peak value of each echo signal and the configuration parameters can be as follows: From the range Doppler map, obtain the distance corresponding to the peak value of the echo signal of each channel in each transmitter group, and calculate the distance difference between the echo signals of each channel in each transmitter group. For example, for a radar with two cascaded radar chips, a transmitter group includes: transmitter Tx1 on radar chip A and transmitter Tx4 on radar chip B. Calculate the distance difference ΔR = |R1-R4| between the distance R1 corresponding to the echo signal ES1 from transmitter Tx1 on radar chip A and the distance R4 corresponding to the echo signal ES4 from transmitter Tx4 on radar chip B. Then, the frequency offset between echo signal ES1 and echo signal ES4 is:

[0101]

[0102] Next, as Figure 6 Taking a radar with two cascaded radar chips as an example, the steps of the channel separation method for a BFDM+TDM / DDM / CDM radar are explained in detail. Figure 6 Radar chip A and radar chip B are cascaded; the transmitters Tx1, Tx2, and Tx3 on radar chip A, as well as the receivers Rx1, Rx2, Rx3, and Rx4, share the first linear frequency modulated (LFM) signal generator, the center frequency of which is f. c The transmitters Tx4, Tx5, and Tx6 on radar chip B, as well as the receivers Rx5, Rx6, Rx7, and Rx8, share a second linear frequency modulated (LFM) signal generator. The center frequency of the second LFM signal generator is f. c +f Δ The transmitter grouping method configured in the radar is shown in Table 1. For each receiver on radar chip A / B, it can receive the echo signals corresponding to the transmitted signals of transmitters Tx1, Tx2 and Tx3 on radar chip A, and the echo signals corresponding to the transmitted signals of transmitters Tx4, Tx5 and Tx6 on radar chip B.

[0103] In a specific example, if Figure 6 The radar in the paper adopts a channel separation method based on BFDM+TDM, that is, radar chip A and radar chip B are in TDM mode. In this case, each time unit uses only one group of transmitters in the transmitter group to transmit signals. The configuration of the transmitted signals is shown in Table 2.

[0104] Table 2

[0105]

[0106]

[0107] Figure 10 This is the time-frequency diagram of the hybrid echo signal received by the receiver in BFDM+TDM mode, such as... Figure 10 As shown, in each time unit, only the echo signals corresponding to the transmitted signals of the transmitters within a transmitter group are received. Echo signals corresponding to Tx1 and Tx4 are received in Time slot 1; echo signals corresponding to Tx2 and Tx5 are received in Time slot 2; and echo signals corresponding to Tx3 and Tx6 are received in Time slot 3. Furthermore, there is a frequency offset between the two echo signals received in each time unit. Therefore, it can be determined that the echo signals received in Time slot 1 originate from transmitter Tx1 on radar chip A and Tx4 on radar chip B, respectively. Thus, in the BFDM+TDM-based channel separation method, channel separation can be achieved based on the frequency offset between the echo signals corresponding to the two transmitters within a transmitter group received in each time unit.

[0108] In another specific example, if Figure 6 The radar in the paper adopts a channel separation method based on BFDM+CDM, that is, radar chip A and radar chip B are in CDM mode. In this case, during the transmission cycle, the phase codes of the transmitted signals of the transmitters in a group of transmitters are the same. The configuration of the transmitted signals is shown in Table 3.

[0109] Table 3

[0110] Phase Code Radar chip A Radar chip B Phase code 1: [0°, 0°, 0°, 0°, ...] Tx1 Tx4 Phase code 2: [0°, 0°, 180°, 180°, ...] Tx2 Tx5 Phase code 3: [0°, 180°, 0°, 180°, ...] Tx3 Tx6

[0111] Figure 11 This is the time-frequency diagram of the hybrid echo signal received by the receiver in BFDM+CDM mode, such as... Figure 11 As shown, echo signals with the same phase number within each transmission cycle can be identified as echo signals corresponding to the transmitted signals of transmitters within a group of transmitters. This allows for the identification of three groups of echo signals with the same phase number: the first group consists of echo signals corresponding to Tx1 and Tx4, the second group consists of echo signals corresponding to Tx2 and Tx5, and the third group consists of echo signals corresponding to Tx3 and Tx6. Furthermore, there is a frequency offset between the two echo signals in each group. Based on the phase code corresponding to each transmitter group and the frequency offset between the two echo signals in each group, it can be determined that the received echo signals within each transmission cycle originate from transmitter Tx1 on radar chip A and Tx4 on radar chip B, respectively. Therefore, in the BFDM+CDM-based channel separation method, channel separation can be achieved based on whether the phase codes of the received echo signals are the same and the frequency offset between two echo signals with the same phase code within each transmission cycle.

[0112] In yet another specific example, if Figure 6 The radar in the paper adopts a channel separation method based on BFDM+DDM, that is, radar chip A and radar chip B are in DDM mode. In this case, during the transmission cycle, the chirp increment of the transmitted signal of the transmitter in a group of transmitters is the same. The configuration of the transmitted signal is shown in Table 4.

[0113] Table 4

[0114] Phase Code Radar chip A Radar chip B <![CDATA[Phase encoding 1: [0, φ1, 2φ1, 3φ1, …]]]> Tx1 Tx4 <![CDATA[Phase encoding 2: [0, φ2, 2φ2, 3φ2, …]]]> Tx2 Tx5 <![CDATA[Phase encoding 3: [0, φ3, 2φ3, 3φ3, …]]]> Tx3 Tx6

[0115] Figure 12 This is the time-frequency diagram of the mixed echo signal received by the receiver in BFDM+DDM mode. For example... Figure 12 As shown, echo signals with the same phase number and whose phase number increments with time within each transmission cycle can be identified as echo signals corresponding to the transmitted signals of transmitters within a transmitter group. This allows for the identification of three groups of echo signals with the same phase number: the first group corresponds to echo signals Tx1 and Tx4, the second group to echo signals Tx2 and Tx5, and the third group to echo signals Tx3 and Tx6. Furthermore, there is a frequency offset between the two echo signals in each group. Based on the phase code corresponding to each transmitter group and the frequency offset between the two echo signals in each group, it can be determined that the received echo signals within each transmission cycle originate from transmitter Tx1 on radar chip A and transmitter Tx4 on radar chip B, respectively. Therefore, in the BFDM+DDM-based channel separation method, channel separation can be achieved based on whether the phase codes of the received echo signals are the same, whether the phase number increments with time are consistent, and the frequency offset between two echo signals with the same phase code and whose time increments are consistent within each transmission cycle.

[0116] Example 3

[0117] Figure 13 This is a schematic diagram of the structure of a radar channel separation device provided in Embodiment 3 of the present invention. Figure 13 As shown, the device includes:

[0118] The signal receiving module 310 is used to receive the mixed echo signal through the receiver on the radar chip and obtain the configuration parameters of the radar; the mixed echo signal includes: the echo signal obtained by each of the m transmitters on each radar chip transmitting signals to the target.

[0119] Processing module 320 is used to perform a two-dimensional Fourier transform on the mixed echo signal to obtain the range Doppler map of the mixed echo signal;

[0120] Extraction module 330 is used to extract all peaks in the distance Doppler image and treat each peak as an echo signal of a channel;

[0121] The grouping module 340 is used to group the echo signals of each channel according to the preset multiplexing modulation mode of the radar chip, and obtain the echo signal corresponding to each transmitter group.

[0122] The determination module 350 is used to determine the transmitter corresponding to each echo signal based on the distance of the peak value of each echo signal in the distance-Doppler graph and the configuration parameters for each channel echo signal in each transmitter group.

[0123] Optionally, the determining module 350 is specifically used for:

[0124] The frequency offset between each echo signal is determined based on the distance corresponding to the peak value of each echo signal and the configuration parameters.

[0125] The transmitter corresponding to each echo signal is determined based on the frequency offset.

[0126] The radar channel separation device provided in this embodiment of the invention can execute the radar channel separation method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method.

[0127] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0128] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A radar, characterized in that, The radar comprises: N radar chips connected in a cascaded manner, each radar chip having m transmitters and n receivers, where N≥2 and N, m, and n are all positive integers; the m transmitters and n receivers on each radar chip share a linear frequency modulated signal generator; there is a frequency offset between the center frequencies of the frequency-modulated continuous waves generated by the linear frequency modulated signal generators of any two radar chips; The transmitter's transmitted signal is obtained by modulating the frequency-modulated continuous wave through a preset multiplexing modulation method. The receiver uses the frequency-modulated continuous wave as a de-linearized frequency modulation signal to perform channel separation on the received mixed echo signal. The receiver receives transmitted signals from different radar chips with different beat frequencies.

2. The radar according to claim 1, characterized in that, The transmitters on N radar chips form M transmitter groups. Each transmitter group includes one transmitter on each radar chip, and each transmitter belongs to only one transmitter group.

3. The radar according to claim 1, characterized in that, The receiver on the radar chip has the following structures: orthogonal structure and non-orthogonal structure.

4. The radar according to claim 3, characterized in that, The frequency offset is one-Nth of the radar's sampling frequency.

5. The radar according to claim 1, characterized in that, Each of the radar chips is configured with a code division multiplexing modulation mode.

6. The radar according to claim 1, characterized in that, Each of the radar chips is configured in a time-division multiplexing modulation mode.

7. The radar according to claim 1, characterized in that, Each of the radar chips is configured with a Doppler frequency division multiplexing modulation mode.

8. A channel separation method for radar, characterized in that, The method is applied to a radar chip in any one of the radars described in claims 1-7; the method includes: The radar chip receives the mixed echo signal through a receiver and obtains the radar's configuration parameters; the mixed echo signal includes the echo signals obtained by m transmitters on each radar chip transmitting signals to the target. A two-dimensional Fourier transform is performed on the mixed echo signal to obtain the range Doppler map of the mixed echo signal; Extract all peaks from the distance Doppler image and treat each peak as an echo signal of one channel; The echo signals of each channel are grouped according to the preset multiplexing modulation mode of the radar chip to obtain the echo signal corresponding to each transmitter group. For the echo signal of each channel in each transmitter group, the transmitter corresponding to each echo signal is determined based on the distance of the peak value corresponding to each echo signal in the distance Doppler graph and the configuration parameters.

9. The method according to claim 8, characterized in that, Determining the transmitter corresponding to each echo signal based on the distance of the peak value corresponding to each echo signal in the distance-Doppler map and the configuration parameters includes: The frequency offset between each echo signal is determined based on the distance corresponding to the peak value of the echo signal and the configuration parameters; The transmitter corresponding to each echo signal is determined based on the frequency offset.

10. A channel separation device for radar, characterized in that, The device is used in a radar chip according to any one of claims 1-7, the device comprising: The signal receiving module is used to receive the mixed echo signal through the receiver on the radar chip and obtain the configuration parameters of the radar; the mixed echo signal includes: the echo signal obtained by each of the m transmitters on each radar chip transmitting signals to the target. The processing module is used to perform a two-dimensional Fourier transform on the mixed echo signal to obtain the range Doppler map of the mixed echo signal; An extraction module is used to extract all peaks in the distance Doppler image and treat each peak as an echo signal of one channel. The grouping module is used to group the echo signals of each channel according to the preset multiplexing modulation mode of the radar chip, so as to obtain the echo signal corresponding to each transmitter group. The determination module is used to determine the transmitter corresponding to each echo signal based on the distance of the peak value corresponding to each echo signal in the distance Doppler graph and the configuration parameters for each channel echo signal in each transmitter group.

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