Apparatus for distributed coherent radar system

Abstract

An apparatus comprising: a controller configured to control transmissions through a distributed coherent radar (DCR) system; and a processor configured to process a radar signal received by the DCR system; wherein the controller is configured to: provide a plurality of transmit antennas from a first radar head of the DCR system and transmit a first chirp from a first predetermined antenna in a first frequency band and through a second predetermined antenna of a second head in a second frequency band; and providing a plurality of transmit antennas from a second radar head, transmitting a second chirp from the second predetermined antenna in a fourth frequency band and through the first predetermined antenna in a third frequency band; and the processor is configured to determine a phase noise estimate based on the received signal.

Description

Technical Field

[0001] This disclosure relates to an apparatus for use with a distributed coherent radar system. Background Technology

[0002] Distributed coherent radar systems are configured to transmit signals from two or more radar heads and simultaneously receive any reflected signals as well as signals transmitted between antennas on the same head and antennas on different heads. Effectively processing the received signals remains a challenge. Summary of the Invention

[0003] According to a first aspect of this disclosure, an apparatus is provided, comprising:

[0004] The controller is configured to control the transmission via a distributed coherent radar (DCR) system.

[0005] A processor configured to process radar signals received by the DCR system;

[0006] The controller is configured to:

[0007] A first control signal is generated, configured to provide transmission of a first chirp from a plurality of transmit antennas of a first radar head of the DCR system via the DCR system and to provide transmission of the first chirp from a first predetermined antenna of the first radar head, and to restrict transmission of the first chirp to a second predetermined antenna of a second radar head of the DCR system, wherein the first control signal is configured to provide transmission of the first chirp through the first predetermined antenna in a first predetermined frequency band and through the second predetermined antenna in a second predetermined frequency band, wherein the first predetermined frequency band and the second predetermined frequency band are different from one or more frequency bands that cause the transmit antennas of the first radar head to transmit the first chirp; and

[0008] A second control signal is generated, configured to provide transmission of a second chirp from multiple transmission antennas of the second radar head via the DCR system after the first chirp, and to provide transmission of the second chirp from a second predetermined antenna of the second radar head, and to restrict transmission of the second chirp to the first predetermined antenna of the first radar head, wherein the second control signal is configured to provide transmission of the second chirp in a third predetermined frequency band via the first predetermined antenna of the first radar head and in a fourth predetermined frequency band via the second predetermined antenna, wherein the third predetermined frequency band and the fourth predetermined frequency band are different from one or more frequency bands that cause the transmission antenna of the second radar head to transmit the second chirp; and

[0009] The processor is configured to:

[0010] In response to the generation of the first control signal, a first radar signal is received from the first radar head of the DCR system;

[0011] In response to the generation of the first control signal, a second radar signal is received from the second radar head of the DCR system;

[0012] A first phase noise estimate is determined based on a first radar signal component comprising a portion of the first radar signal within the second predetermined frequency band and a second radar signal component comprising a portion of the second radar signal within the first predetermined frequency band; and the first radar signal component and the second radar signal component are used to determine a first phase noise estimate.

[0013] In response to the generation of the second control signal, a third radar signal is received from the first radar head of the DCR system;

[0014] In response to the generation of the second control signal, a fourth radar signal is received from the second radar head of the DCR system;

[0015] A second phase noise estimate is determined based on a component third radar signal that includes a portion of the third radar signal in the fourth predetermined frequency band and a component fourth radar signal that includes a portion of the fourth radar signal in the third predetermined frequency band.

[0016] In one or more embodiments, the device includes the DCR system, the DCR system comprising:

[0017] The first radar head includes: the plurality of transmitting antennas and the first predetermined antenna, the plurality of transmitting antennas and the first predetermined antenna being configured to provide a transmission chirp; and a plurality of receiving antennas configured to receive one or more reflected signals including the chirp and to generate at least a first radar signal and the third radar signal based on the received signals, wherein the first radar head provides the transmission of the chirp and the reception of the signals based on a first time reference; and

[0018] The second radar head has: the plurality of transmitting antennas and the second predetermined antenna, the plurality of transmitting antennas and the second predetermined antenna being configured to provide a transmitting chirp; and a plurality of receiving antennas being configured to receive one or more reflected signals including the chirp and to generate at least a second radar signal and the fourth radar signal based on the received signals, wherein the second radar head provides the transmitting chirp and the receiving signals based on a second different time reference.

[0019] In one or more embodiments, the first predetermined antenna of the first radar head includes a single transmit-receive antenna configured to transmit a corresponding chirp and simultaneously receive the one or more reflected signals including the chirp for processing by the processor; and

[0020] The second predetermined antenna of the second radar head includes a single transmit-receive antenna configured to transmit the corresponding chirp and simultaneously receive the signal including the one or more reflections of the chirp for processing by the processor.

[0021] In one or more embodiments, the first control signal is configured to provide the first chirp to be transmitted via the DCR system from the first predetermined antenna of the first radar head and the second predetermined antenna of the second radar head at a power lower than the power transmitted by each of the plurality of transmission antennas for the first radar head; and

[0022] The second control signal is configured to provide the second chirp to be transmitted via the DCR system from the first predetermined antenna of the first radar head and the second predetermined antenna of the second radar head at a power lower than the power transmitted by each of the plurality of transmission antennas for the second radar head.

[0023] In one or more embodiments, the first predetermined frequency band is the same as the fourth predetermined frequency band, and the second predetermined frequency band is the same as the third predetermined frequency band.

[0024] In one or more embodiments, the controller is configured to apply a frequency shift to one of the first time reference and the second time reference to cause a frequency offset between the first time reference and the second time reference.

[0025] In one or more embodiments, the controller is configured to generate a transmission control signal including the first control signal and the second control signal, the transmission control signal being configured to cause the transmission of chirp from the plurality of transmission antennas of the first head and the plurality of transmission antennas of the second head to be based on a Doppler division multiple access waveform.

[0026] In one or more embodiments, the processor is configured to downconvert the first radar signal and the third radar signal from the first radar head to an intermediate frequency range, and to downconvert the second radar signal and the fourth radar signal from the second radar head to the intermediate frequency range.

[0027] In one or more embodiments, the device includes one or more phase rotators configured such that the component second radar signal and the component third radar signal are located in the middle and / or at the upper and lower ends of the intermediate frequency range.

[0028] In one or more embodiments, the transmission control signal is configured such that each of the plurality of transmission antennas of the first radar head and each of the plurality of transmission antennas of the second radar head are configured to transmit each chirp with a predetermined phase change; and

[0029] The processor is configured to provide a phase shift to each chirp that reverses the predetermined phase change.

[0030] In one or more embodiments, the predetermined phase change is pseudo-random.

[0031] In one or more embodiments, the processor and the controller are provided by a single DCR control device.

[0032] In one or more embodiments, the device includes a vehicle, and the DCR system includes automotive radar for the vehicle.

[0033] According to a second aspect of this disclosure, we provide a method for operating a distributed coherent radar (DCR) system, the method comprising:

[0034] A first control signal is generated, the first control signal being configured to provide transmission of a first chirp from a plurality of transmission antennas of a first radar head of the DCR system via the DCR system and to provide transmission of the first chirp from a first predetermined antenna of the first radar head, and to restrict transmission of the first chirp to a second predetermined antenna of a second radar head of the DCR system, wherein the first control signal is configured to provide transmission of the first chirp through the first predetermined antenna in a first predetermined frequency band and through the second predetermined antenna in a second predetermined frequency band, wherein the first predetermined frequency band and the second predetermined frequency band are different from one or more frequency bands that cause the transmission antennas of the first radar head to transmit the first chirp;

[0035] In response to the generation of the first control signal, a first radar signal is received from the first radar head of the DCR system;

[0036] In response to the generation of the first control signal, a second radar signal is received from the second radar head of the DCR system;

[0037] A first phase noise estimate is determined based on a first radar signal comprising a component of the first radar signal in the second predetermined frequency band and a component of the second radar signal comprising a component of the second radar signal in the first predetermined frequency band.

[0038] A second control signal is generated, the second control signal being configured to provide transmission of a second chirp from a plurality of transmission antennas of the second radar head after the first chirp via the DCR system, and to provide transmission of the second chirp from a second predetermined antenna of the second radar head, and to restrict transmission of the second chirp to the first predetermined antenna of the first radar head, wherein the second control signal is configured to provide transmission of the second chirp in a third predetermined frequency band via the first predetermined antenna of the first radar head and in a fourth predetermined frequency band via the second predetermined antenna, wherein the third predetermined frequency band and the fourth predetermined frequency band are different from one or more frequency bands that cause the transmission antenna of the second radar head to transmit the second chirp;

[0039] In response to the generation of the second control signal, a third radar signal is received from the first radar head of the DCR system;

[0040] In response to generating the second control signal, a fourth radar signal is received from the second radar head of the DCR system; and

[0041] The second phase noise estimate is determined based on the components of the third radar signal that include a portion of the third radar signal in the fourth predetermined frequency band and the components of the fourth radar signal that include a portion of the fourth radar signal in the third predetermined frequency band.

[0042] In one or more embodiments, the method includes:

[0043] The first radar head of the DCR system includes receiving the first radar signal and the third radar signal from the first predetermined antenna;

[0044] The second radar head of the DCR system receives the second radar signal and the fourth radar signal from the second predetermined antenna.

[0045] While this disclosure allows for various modifications and alternatives, details of this disclosure have been shown by way of example in the drawings and will be described in detail. However, it should be understood that other embodiments besides the specific embodiments described may also exist. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are also covered.

[0046] The above discussion is not intended to represent every example embodiment or every implementation within the scope of the current or future set of technical solutions. The following figures and detailed descriptions further illustrate various example embodiments. A more comprehensive understanding of these various example embodiments can be achieved by considering the following detailed descriptions in conjunction with the figures. Attached Figure Description

[0047] One or more embodiments will now be described by way of example only with reference to the accompanying drawings, in which:

[0048] Figure 1 An example embodiment of a device including a distributed coherent radar (DCR) system is shown;

[0049] Figure 2 An example configuration of the transmit and receive antennas in the two radar heads of this type of DCR system is shown;

[0050] Figure 3 An example range Doppler plot of radar signals received from a first radar head and radar signals received from a second radar head against a first chirp is shown.

[0051] Figure 4 Example range Doppler plots of radar signals received from a first radar head and radar signals received from a second radar head are shown for a subsequent second chirp; and

[0052] Figure 5 An example of how the device is operated is shown. Detailed Implementation

[0053] Examples of this disclosure relate to the control of a distributed coherent radar (DCR) system. These examples describe controlling the DCR system in a specific manner to transmit chirped signals and processing received radar signals in a specific manner, which in some embodiments can improve the effectiveness of the DCR system.

[0054] Figure 1Device 100 is shown, which in this example includes a distributed coherent radar (DCR) system 101. Device 100 further includes: a controller 102 configured to control the transmission of radar signals, such as chirped signals, via the DCR system 101; and a processor 103 configured to process radar signals received by the DCR system 101. It should be understood that device 100 may include controller 102 and processor 103 without DCR system 101, and therefore controller 102 and processor 103 may be configured to be coupled to the DCR system and control / receive radar signals from the DCR radar system 101 to which they are coupled. Furthermore, for ease of understanding, controller 102 and processor 103 are shown as separate functional elements in the present example, but they may be provided as a single DCR control device. Generally, one or more entities that provide the functionality of processor 103 and controller 102 may take different forms, such as (i) one or more processors having associated memory storing computer program code configured to provide the functionality described herein, (ii) one or more ASICs, (iii) one or more FPGAs, (iv) hardware and software elements, or (v) combinations thereof.

[0055] refer to Figure 1 and 2 The DCR system 101 includes a first radar head 105 and a second radar head 106. Radar heads 105 and 106 are configured to at least partially transmit radar signals into the same area of ​​space. The radar heads are spaced apart, which is typical in DCR systems.

[0056] The first radar head 105 has multiple transmission antennas 107 and multiple receiving antennas 108. Figure 1 The image schematically shows multiple transmit and receive antennas 107 and 108. More details are shown in the image below. Figure 2 In this embodiment, and as those skilled in the art will understand, the first radar head includes a plurality of transmit antennas 201, 202 and a plurality of receive antennas 203, 204 arranged to form an antenna array. In the present example, the first radar head includes an antenna 205, which includes a combined transmit-receive antenna or a co-located antenna. Antenna 205 may be referred to as the “first predetermined antenna” of the first radar head 105. In the present example, there is a single first predetermined antenna, but in other examples, there may be multiple first predetermined antennas.

[0057] Similarly, the second radar head 106 has multiple transmit antennas 110 and multiple receive antennas 111. Figure 1 The image schematically illustrates multiple transmit and receive antennas 110 and 111. More details are shown in the image below. Figure 2As those skilled in the art will understand, the second radar head includes a plurality of transmit antennas 206, 207 and a plurality of receive antennas 208, 209 arranged to form an antenna array. In the present example, the second radar head 106 includes an antenna 210, which includes a combined transmit-receive antenna or a co-located antenna. Antenna 210 may be referred to as the “second predetermined antenna” of the second radar head 106. In the present example, there is a single second predetermined antenna, but in other examples, there may be multiple second predetermined antennas.

[0058] Therefore, controller 102 is configured to provide control signals to each of the first radar head 105 and the second radar head 106 to provide transmitted chirps from one or more of the respective antennas 201, 202, 205 and / or 206, 207, 210. The control signals can control one or more of the following: the frequency of the chirp, the phase of the chirp, the waveform of the chirp, the timing of the chirp, and which antennas are used at any given time.

[0059] Radar heads 105, 106, and in particular receiving antennas 203, 204, 205, 208, 209, 210, are configured to receive signals 211, 212 from the environment, such as chirps reflected from one or more objects 213. Radar signals representing the received reflections and other signal content are provided from each radar head to processor 103, as shown by lines 112, 113. Lines 112, 113 may represent an Ethernet connection.

[0060] Each radar head 105, 106 has its own local clocks 114 and 115, respectively. Therefore, the first radar head 105 provides the transmission chirp and processes the received signal based on a first time reference provided by clock 114 to provide the radar signal to processor 103. Similarly, the second radar head 106 provides the transmission chirp and processes the received signal based on a second time reference provided by clock 115 to provide the radar signal to processor 103. Processing the received signal to generate the radar signal provided to processor 103 may include one or more of the following: filtering by one or more filters, down-converting (also referred to as down-mixing) to an intermediate frequency by one or more mixers, phase shifting by one or more phase rotators, and / or analog-to-digital conversion by an ADC circuit arrangement.

[0061] As will be described in more detail below, a single combined transmit-receive antenna for each head is used for phase noise estimation. In other examples, there may be more than one combined transmit-receive antenna in each radar head, but in this example, only one combined transmit-receive antenna is required for phase noise estimation as described later in this document.

[0062] We will now describe, in some examples, the problems that embodiments of this disclosure can solve. Generally, the DCR system 101 uses multiple radar heads 105, 106 to detect target 213 with improved angular resolution. Radar signals from radar heads 105, 106 are processed together by processor 103.

[0063] Controller 103 is configured to provide control signals to radar heads 105, 106 to transmit radar signals in the same frequency band. These signals, after being reflected by target / object 213, will also be received in the same frequency band. After down-mixing in the receiver chain within the respective radar head, a so-called beat signal is obtained. In the DCR system, phase noise in the received signal increases during down-mixing because the signal used for down-mixing is generated using a different time reference or clock 114, 115 than the time reference or clock used during up-conversion, since the process is performed in a different radar head for at least a portion of the received signal.

[0064] Furthermore, in the DCR system, strong spurious signals exist from the transmitting antennas 201, 202, 205 to the receiving antennas 203, 204, 205 of the same radar head. This signal is called a monostatic spill-over signal. This spurious signal generates a low-frequency beat signal. In the current example, filters (not shown) can be provided in each respective radar head 105, 106, and these filters are configured to suppress this beat signal. For example, an analog high-pass filter (not shown) can be provided to filter the received signal before digitizing it via an analog-to-digital converter (ADC) to prevent clipping in the ADC within the radar head.

[0065] Furthermore, in the DCR system, there is a so-called bistatic spill-over signal because there are direct paths between the transmitting antennas 201, 202, 205 / 206, 207, 210 on one radar head and the receiving antennas 208, 209, 210 / 203, 204, 205 on the other radar head.

[0066] It has been found that the strength of this bistatic overflow signal depends on the spacing of radar head 105, 106. It has also been found that strong bistatic signals can be caused by nearby targets 213 with high radar cross-sections (RCS). Therefore, one or more filters can be provided to ensure that these (high-amplitude) bistatic signals do not cause clipping in the ADC of the radar head.

[0067] The processor 103 can be configured to use simultaneously received bistation signals to determine information for the synchronization of the first radar head 105 and the second radar head 106.

[0068] As mentioned above, the chirped and radar signals transmitted and received from the transmit-receive antennas 205 and 210 are used to estimate phase noise, enabling compensation to be provided.

[0069] Before the processor 103 determines the phase noise estimate, the radar signals received at the transmit-receive antennas 205 and 210 must be separated from the radar signals received at the other antenna. One way to achieve this separation is to use separate frequency bands for these transmit-receive antennas 205 and 210, but further measures can be applied to make the use of separate frequency bands more effective. It should be explained that, without additional measures, using separate frequency bands for transmit-receive antennas 205 and 210 means that the lower intermediate frequency (IF) spectrum (i.e., after downmixing) can be used by other transmit antennas 201, 202, 206, and 207, which can reduce range resolution.

[0070] Furthermore, the frequency shifting for transmission by the transmit-receive antennas 205 and 210 typically requires the use of phase rotators. These phase rotators are known to be imperfect and introduce spurious signals into the so-called range Doppler graph without additional measures.

[0071] Furthermore, it is known that beat signals in DCR systems typically do not have a constant frequency, even if the observed scene is static, i.e., the target is stationary. This non-constant frequency is a result of frequency offset between the two radar heads 105 and 106 due to the use of different clocks 114 and 115, which are inherently different. Therefore, due to, for example, clock domain crossover, the start time of the chirp sequence typically does not occur at exactly the same point in time in the two radar heads 105 and 106.

[0072] We will now describe the operation of an example device 100 that can address one or more of the potential limitations of a DCR system.

[0073] In the current example, the controller 102 and processor 103 are configured to provide a MIMO scheme for the DCR system 101.

[0074] In the current example, the transmission antenna of one of the first head 105 and the second head 106 is activated to transmit chirp, while the transmission antenna of the other of the first head 105 and the second head 106 is deactivated or restricted to prevent chirp transmission. However, in order to perform phase noise estimation, it has been determined that providing limited transmission from both radar heads (i.e., from the first or second predetermined antenna) via, for example, the transmit-receive antennas 205 and 210 may be advantageous.

[0075] Therefore, generally, controller 102 is configured to generate first control signals, which are configured to provide transmission of a first chirp from the transmission antennas 201, 202 of the first radar head 105 and from the first predetermined antenna 205. These first control signals may restrict the transmission of the first chirp to be transmitted only through the transmit-receive antenna 210 of the second radar head 106.

[0076] The controller 102 is then configured to transmit a subsequent second chirp, such as a next chirp, from the second radar head 106. Therefore, the controller 102 can be configured to generate a second control signal configured to provide transmission of the subsequent second chirp from the transmit antennas 206, 207 of the second radar head 106 and from the second predetermined antenna 210. Similarly, the second control signal is configured to restrict the transmission of the second chirp to the transmit-receive antenna 205 of the first radar head 105.

[0077] It should be understood that control signals are configured to limit transmission by preventing transmission altogether, rather than by stopping transmission. We have found that for phase noise estimation, it is beneficial for the radar head, which never uses a transmission antenna, to perform some limited transmission.

[0078] It should be understood that reflected, monostatic, and bistatic signals are received by radar heads 105, 106 during and shortly after the transmission caused by the respective first and second control signals. Conventionally, radar heads 105, 106 may include components providing filtering, down-mixing, and analog-to-digital conversion. However, processor 102 will be configured to receive radar signals representing the received signals at each respective radar head. Processor 103 may then be configured to:

[0079] Receiving a first radar signal from the first radar head 105 in response to a signal received after transmission caused by the generation of a first control signal; and

[0080] The second radar signal is received from the second radar head in response to the signal received after the transmission caused by the generation of the first control signal.

[0081] The processor 102 can then extract radar signals from the transmit-receive antenna 210 and the transmit-receive antenna 205, and determine a first phase noise estimate based on the extracted radar signals.

[0082] Similarly, if we consider the second chirp, then processor 103 is configured as follows:

[0083] Receive from the first radar head 105 a third radar signal representing the signal received after transmission caused by the generation of the second control signal; and

[0084] The fourth radar signal, representing the signal received after the transmission caused by the generation of the second control signal, is received from the second radar head 106.

[0085] The processor 102 can then extract radar signals from the transmit-receive antenna 205 and the transmit-receive antenna 210, and determine a second phase noise estimate based on the extracted radar signals.

[0086] How to calculate phase noise estimation is not the subject of this application. Instead, it is advantageous to determine which portion of the received radar signal is used for phase noise estimation (and thus, to determine what content is transmitted by which antenna). However, those skilled in the art will understand that phase noise is a phase impurity of the RF carrier and is added to the transmitted chirp / signal in the upmixing portion of the RF front-end in the radar head. When the same RF carrier is used for downmixing, a time-shifted version of the phase noise signal is subtracted from the received signal. Therefore, in monostation radar sensing, a portion of the phase noise is eliminated. The portion of phase noise eliminated is the so-called time-correlated portion: the flight time of the received signal is small compared to the phase noise decorrelation time, the phase noise component in the transmitted signal / chirp will be highly correlated with the phase noise in the RF carrier used for downmixing, and therefore, a large portion of the phase noise will be eliminated. Due to the independent clocks 114 and 115, and the independent generation of the RF carrier, the phase noise implementation in radar heads 105 and 106 is uncorrelated. Therefore, upmixing in radar head 105 and downmixing in radar head 106 will not eliminate phase noise. Having phase noise implementations phi1(t) and phi2(t) in radar head 105, the effective phase noise component in the received signal in radar head 105 will be phi2(t) - phi1(t), and in radar head 106, it will be phi1(t) - phi2(t). Therefore, the total phase noise implementations in the two bistatic signals will have opposite signs. In addition to phase noise, the received bistatic signal will also contain phase information related to all reflections in the radar scene. Since the combined transmit-receive antennas 205 and 210 provide the same radar scene information contained in the phase in the received bistatic signal (up to constant phase). Therefore, when we subtract the phase information contained in the two bistatic signals, the radar scene information will be eliminated, and the resulting signal will contain only 2x(phi1(t) - phi2(t)) as phase information. Therefore, the estimated value phi1(t) - phi2(t) can be estimated and added to the signal from radar head 105 and subtracted from the signal from radar head 106.

[0087] Therefore, it is advantageous to estimate the phase noise for each chirp of the corresponding radar head or for each sample received from the ADC.

[0088] It has been recognized that for targets at closer range, it is necessary to suppress phase noise. Therefore, it is advantageous to provide control over the DCR system 101 that performs phase noise estimation.

[0089] To extract the contribution of the radar signals received by the transmit-receive antennas 205 and 210 at the radar head 105 and 106, the controller is configured to cause the transmit-receive antennas 205 and 210 to transmit in a predetermined frequency band, which may be considered a synchronization band, or simply an S-band. In this disclosure, a first predetermined frequency band, a second predetermined frequency band, a third predetermined frequency band, and a fourth predetermined frequency band are described; however, in the following examples, two predetermined frequency bands are used.

[0090] To further explain, we refer to the example shown in the Doppler graph. Figure 3 and 4 .

[0091] Figure 3 A first range Doppler image 301 is shown, which illustrates the signal content of the radar signal received from the first radar head 105 after the first chirp. Figure 3 A second range Doppler image 302 is also shown, illustrating the signal content of the radar signal received from the second radar head 106 after the first chirp. As mentioned above, the first chirp is transmitted by the transmission antennas 201 and 202 of the first radar head 105, the first predetermined antenna 205 (in the first S-band), and the transmit-receive antenna 210 of the second radar head 106 (in the second S-band).

[0092] Figure 4 A first range Doppler image 401 is shown, which illustrates the signal content of the radar signal received from the first radar head 105 after the second chirp. Figure 4 A second range Doppler image 402 is also shown, illustrating the signal content of the radar signal received from the second radar head 106 after the second chirp. As mentioned above, the second chirp is transmitted by the transmission antennas 206 and 207 of the second radar head 106, the second predetermined antenna 210 (in the fourth S-band, which in this example is the same band as the first) and the transmit-receive antenna 205 of the first radar head 105 (in the third S-band, which in this example is the same band as the second S-band).

[0093] The single-station signal content, indicated by dashed arrows, and the bi-station signal content, indicated by solid arrows, are shown in these range Doppler maps. The arrows indicate the location where the target will appear in the range Doppler map.

[0094] For the first chirp, the transmission antenna of the first radar head is active. Therefore, zone 303 includes the monostation signal content transmitted and received by the first head. The two arrows indicate the content originating from the corresponding transmission antennas 201 and 202.

[0095] Zone 304 represents the first predetermined frequency band. The first predetermined antenna 205 uses the first predetermined frequency for the first chirp, and therefore, zone 304 shows the monostation signal content transmitted by and received by the first head.

[0096] Section 305 indicates the second predetermined frequency band. The second predetermined antenna 210 uses the second predetermined frequency for the first chirp, and therefore, section 305 shows the bistation signal content transmitted by the second head and received by the first head.

[0097] For the first chirp, the transmission antennas 206 and 207 of the second radar head are inactive. Therefore, zone 306 includes the signal content transmitted by the transmission antenna of the first head and received by the second head. The two arrows indicate the content originating from the respective transmission antennas 201 and 202.

[0098] Section 307 represents the first predetermined frequency band. The first predetermined antenna 205 uses the first predetermined frequency for the first chirp, and therefore, section 307 shows the bistation signal content transmitted by the first head and received by the second head.

[0099] Section 308 represents the second predetermined frequency band. The second predetermined antenna 210 uses the second predetermined frequency for the first chirp, and therefore, section 308 shows the monostation signal content transmitted by and received by the second head.

[0100] For the second chirp, the transmission antenna of the second radar head is active. Therefore, zone 403 includes the signal content transmitted by the transmission antennas 206 and 207 of the second head and received by the first head. The two arrows indicate the content originating from the respective transmission antennas 206 and 207.

[0101] Section 404 represents the first predetermined frequency band (in the current example, it is the same as the fourth frequency band). The second predetermined antenna 210 uses the fourth / first predetermined frequency for the second chirp, and therefore, section 404 shows the bistation signal content transmitted by the second predetermined antenna 210 of the second head and received by the first head.

[0102] Zone 405 represents the second predetermined frequency band (in the current example, it is the same as the third frequency band). The first predetermined antenna 205 uses the third / second predetermined frequency for the second chirp, and therefore, zone 405 shows the monostation signal content transmitted by the first predetermined antenna 205 of the first head and received by the first head.

[0103] We now refer to Figure 4 .

[0104] For the second chirp, the transmission antenna of the first radar head is inactive. Therefore, zone 406 includes the signal content transmitted by the transmission antenna of the second head and received by the second head. The two arrows indicate the content originating from the corresponding transmission antennas 205 and 206.

[0105] Section 407 represents the first predetermined frequency band (in the current example, it is the same as the fourth frequency band). The second predetermined antenna 210 uses the fourth / first predetermined frequency for the second chirp, and therefore, section 407 shows the monostation signal content transmitted by the second predetermined antenna 210 of the second head and received by the second head.

[0106] Section 408 represents the second predetermined frequency band (in the current example, it is the same as the third frequency band). The first predetermined antenna 205 uses the third / second predetermined frequency for the second chirp, and therefore, section 408 shows the bistation signal content transmitted by the first predetermined antenna 205 of the first head and received by the second head.

[0107] Therefore, by placing the signal transmitted by the transmit-receive antenna within a portion of the spectrum that allows it to be identified in the radar signal, the use of a synchronization band facilitates efficient determination of phase noise estimates. In the most general sense, the controller can use a first to a fourth different predetermined frequency band or S-band for each predetermined antenna 205, 210 on two chimes. However, in other examples, such as the present example, the controller can be configured to provide transmission via the first predetermined antenna 205 and the second predetermined antenna 210 in different predetermined frequency bands during each chime, regardless of which frequency band is selected.

[0108] Therefore, in conclusion, it caused Figure 3 The first control signal for the transmission of the first chirp, as indicated in the diagram, is configured to be provided in a first predetermined frequency band (shown as a synchronization band, as shown in zones 307 (received by the second radar head 106) and 304 (received by the radar head 105), which is different from one or more frequency bands that cause the first radar head to transmit the first chirp (i.e., shown in zones 303 and 306)) through the transmit-receive antenna 205 of the first radar head 105.

[0109] Furthermore, the transmit-receive antenna 210 of the second radar head 106 is also configured to transmit in a second predetermined frequency band (the synchronization band shown by zones 305 and 308) different from the transmit antennas 201 and 202.

[0110] Therefore, causing Figure 4The second control signal for the transmission of the second chirp, as indicated in the diagram, is configured to provide transmission of the second chirp via the transmit-receive antenna 210 in a fourth (first) predetermined frequency band (the synchronization band shown in zones 404, 407) that is different from one or more frequency bands that cause the second radar head 106 to transmit the second chirp (i.e., shown in zones 403, 406).

[0111] Furthermore, the transmit-receive antenna 205 of the first radar head 105 is made to transmit in the third (second) predetermined frequency band (the synchronization band shown by zones 405, 408).

[0112] It was also found that, in some cases, introducing a guard band is advantageous to ensure the complete IF spectrum is available for both monostation and bistation signals, while taking into account the effects of high-pass filtering performed by the analog-to-digital conversion in the corresponding radar heads 105, 106. Therefore, a so-called guard band is introduced to handle the frequency and time offsets caused by independent clocks 114, 115. Controller 102 is configured to apply a frequency shift to one of the first time reference 114 and the second time reference 115 to cause a frequency offset between the first and second time references. Thus, more efficient signal processing can be allowed by slightly shifting the local oscillator frequency of one radar head 105, 106 relative to the other radar head 106, 105.

[0113] In the current example, device 100 provides a MIMO scheme that allows each radar head to apply DDMA to separate radar signals received from individual transmit antennas, enabling the generation of a large virtual antenna array. This MIMO scheme is particularly useful because synchronization between radar heads 105 and 106 can be achieved by estimating the start time offset and frequency offset of the chirp sequence. Therefore, generally, controller 102 is configured to transmit control signals that may include the previously mentioned first and second control signals, the control signals being configured to transmit chirp-based Doppler diversity multiple access waveforms from the plurality of transmit antennas of the first head 105 and the plurality of transmit antennas of the second head 106.

[0114] In some examples, the first and second predetermined frequency bands (also referred to as synchronization bands / s bands) are positioned in the middle and at the ends of the IF spectrum, i.e., at locations 304, 404, 305, 405, etc. The positioning of the first and second predetermined frequency bands can be achieved using phase rotators in the radar head 105, 106. These middle and end positions are chosen because the phase rotator does not introduce spurious signals at these locations. This is because only rotations in multiples of 90° are required. Therefore, the first and second control signals can be configured to provide transmission from the transmit-receive antenna within the respective predetermined frequency bands based on a 90° phase rotation of the phase rotator. With a sampling rate of 40 MHz (for the ADC), the entire IF band is between 0 MHz and 20 MHz (fs / 2), and half of it is 10 MHz (fs / 4). fs / 2 can be achieved by phase shifts of 0, 180, 0, etc., while fs / 4 can be achieved by phase shifts of 0, 90, 180, 270, 0, etc. applied to continuous samples.

[0115] Furthermore, the signal from one of the co-located transmit-receive antennas 205 and 210 appears at a frequency higher than the ADC sampling frequency divided by 2. This results in a surround effect indicating aliasing. Under the aliasing effect, frequencies in the basic interval portion close to fs / 2 will eventually be located in the left portion of the next basic interval as they further increase beyond fs / 2, and will appear as negative frequencies due to aliasing. Since negative and positive frequencies cannot be distinguished in a real (uncomplicated) receiver, they will appear as positive frequencies. Due to this surround and mirror effect, larger distance values ​​will appear as lower (positive) beat frequencies, which is why the arrows in zones 305, 308, 405, and 408 point to the left. Reflecting targets appear as peaks in the range Doppler plot. Due to the increasing distance, a monostatic target in zone 304 will eventually be located in the IF spectrum “belonging” to the bistatic signal in zone 305. The same target considered as a bistatic response will eventually be located in the zone belonging to the monostatic signal in zone 304 for the same reason. Therefore, a target detector that can be implemented by a processor may misinterpret the target, leading to false alarms and false detections. Therefore, target detection at excessively long distances should be avoided as much as possible. One way to suppress unwanted target intensity is to apply a spreading sequence to the chirp. If a different spreading code is applied to each transmitting antenna, the spreading of the desired transmitting antenna can be de-spread at the receiving antenna, and then range-Doppler processing can be applied. In this case, targets beyond the desired distance will not appear as peaks in the unwanted area, but rather as spurious noise. Without loss of generality, one code can be used for odd-numbered chirps transmitted from the second predetermined antenna 210, and the same code can be used for even-numbered chirps transmitted from the first predetermined antenna 205.

[0116] Therefore, in the current example, this effect is mitigated because the transmission control signal is configured to cause all transmission antennas of the corresponding radar head to produce (pseudo)random phase changes for each chirp. This phase change causes the target of the transmission antenna of the other radar head to be diffused and suppressed. Therefore, in some examples, the first predetermined frequency band and the second predetermined frequency band / the first synchronization frequency band and the second synchronization frequency band can overlap, thereby providing more IF spectrum for target identification. By doubling the sampling frequency of the ADC, the same range resolution as when not using sub-bands can be obtained. Another important feature of the device is that the power of the signal transmitted at a frequency in the middle of the IF spectrum can be reduced to prevent clipping in the ADC. This power reduction does not affect the direction of arrival estimation because the antenna signal does not participate in the snapshot creation but is only used for phase noise estimation. The transmission power can be reduced even if the power of individual transmission antennas cannot be controlled. Therefore, refer to Figure 3 In practice, only the second predetermined antenna 210 from the sensor head 106 is used, and therefore the transmission antenna can be set to low power while only the second predetermined antenna 210 is enabled.

[0117] Figure 5 A flowchart is shown, illustrating an example method.

[0118] The method relates to the operation of device 100, which includes: a controller 102 configured to control transmissions via a distributed coherent radar (DCR) system 101; and a processor 103 configured to process radar signals received by the DCR system. The method includes:

[0119] A first control signal 501 is generated, the first control signal being configured to provide transmission of a first chirp from a plurality of transmission antennas of a first radar head of the DCR system via the DCR system, and to limit the transmission of the first chirp to a subset of a plurality of transmission antennas of a second radar head of the DCR system, wherein the first control signal is configured to provide transmission of the first chirp through a subset of transmission antennas of the second radar head in a first predetermined frequency band different from one or more frequency bands that cause the first radar head to transmit the first chirp;

[0120] In response to the generation of a first control signal, the 502 first radar signal is received from the first radar head of the DCR system;

[0121] In response to the generation of a first control signal, the 503 second radar signal is received from the second radar head of the DCR system;

[0122] The first phase noise estimate (504) is determined based on the components of the second radar signal, which include a portion of the second radar signal within the first predetermined frequency band.

[0123] Furthermore, the method includes:

[0124] A first control signal 501 is generated, the first control signal being configured to provide transmission of a first chirp from a plurality of transmission antennas of a first radar head of the DCR system via the DCR system and to provide transmission of the first chirp from a first predetermined antenna of the first radar head, and to restrict transmission of the first chirp to a second predetermined antenna of a second radar head of the DCR system, wherein the first control signal is configured to provide transmission of the first chirp through the first predetermined antenna in a first predetermined frequency band and through the second predetermined antenna in a second predetermined frequency band, wherein the first predetermined frequency band and the second predetermined frequency band are different from one or more frequency bands that cause the transmission antennas of the first radar head to transmit the first chirp;

[0125] In response to the generation of a first control signal, the 502 first radar signal is received from the first radar head of the DCR system;

[0126] In response to the generation of a first control signal, the 503 second radar signal is received from the second radar head of the DCR system;

[0127] The first phase noise estimate is determined based on the components of the first radar signal, which include a portion of the first radar signal in the second predetermined frequency band, and the components of the second radar signal, which include a portion of the second radar signal in the first predetermined frequency band.

[0128] A second control signal is generated, configured to provide transmission of a second chirp from multiple transmission antennas of the second radar head via the DCR system after the first chirp, and to provide transmission of the second chirp from a second predetermined antenna of the second radar head, and to restrict transmission of the second chirp to a first predetermined antenna of the first radar head, wherein the second control signal is configured to provide transmission of the second chirp through the first predetermined antenna of the first radar head in a third predetermined frequency band and through the second predetermined antenna in a fourth predetermined frequency band, wherein the third predetermined frequency band and the fourth predetermined frequency band are different from one or more frequency bands that cause the transmission antenna of the second radar head to transmit the second chirp;

[0129] In response to the generation of a second control signal, the third radar signal 506 is received from the first radar head of the DCR system.

[0130] In response to the generation of a second control signal, the 507 fourth radar signal is received from the second radar head of the DCR system; and

[0131] The second phase noise estimate is determined based on the components of the third radar signal that include a portion of the third radar signal in the fourth predetermined frequency band and the components of the fourth radar signal that include a portion of the fourth radar signal in the third predetermined frequency band.

[0132] The method includes:

[0133] Receive first radar signals and third radar signals from the first radar head of the DCR system, including radar signals originating from the first predetermined antenna;

[0134] The second radar signal and the fourth radar signal are received from the second radar head of the DCR system, including radar signals originating from the second predetermined antenna.

[0135] It should be understood that the first and second frequency bands may be the same or different. However, the first and second frequency bands are configured to provide information on the signal content transmitted by the combined transmit-receive antennas via FDMA technology in the received radar signal. In one example, there are three frequency bands at the sampling frequency f. s In the case of 40 MHz, we have (0 MHz to 10 MHz), (10 MHz to 15 MHz), and (20 MHz to 15 MHz). For the first chirp and the second chirp, we can assign the predetermined antenna 205 to 10 MHz to 15 MHz and the predetermined antenna 210 to (20 MHz to 15 MHz), but we can also swap the frequency bands in the first chirp and the second chirp.

[0136] Unless a specific order is explicitly stated, the instructions and / or flowchart steps in the above diagrams may be performed in any order. Furthermore, those skilled in the art will recognize that while an example set of instructions / method has been discussed, the material in this specification can be combined in various ways to produce other examples, and should be understood within the context of the detailed description provided herein.

[0137] In some example embodiments, the instruction set / method steps described above are implemented as functional and software instructions embodied in an executable instruction set, which is implemented on a computer or a machine programmed and controlled with said executable instructions. Such instructions are loaded to execute on a processor (e.g., one or more CPUs). The term processor includes a microprocessor, microcontroller, processor module or subsystem (including one or more microprocessors or microcontrollers), or other control or computing device. A processor may refer to a single component or multiple components.

[0138] In other examples, the instruction sets / methods illustrated herein, along with their associated data and instructions, are stored in appropriate storage devices, which are implemented as one or more non-transitory machine- or computer-readable or computer-usable storage media. Such computer-readable or computer-usable storage media are considered part of an article (or article of manufacture). An article or article of manufacture may refer to any single or multiple components manufactured. Non-transitory machine- or computer-usable media as defined herein does not include signals, but such media may be capable of receiving and processing information from signals and / or other transient media.

[0139] Example embodiments of the materials discussed in this specification may be implemented, wholly or in part, via a network, computer, or data-based device and / or service. These may include cloud, internet, intranet, mobile device, desktop computer, processor, lookup table, microcontroller, consumer device, infrastructure, or other supporting devices and services. As may be used herein and in the claims, the following non-exclusive definitions are provided.

[0140] In one example, automating one or more instructions or steps discussed herein. The terms automation or automaticity (and similar variations) mean controlling the operation of equipment, systems, and / or processes using computers and / or mechanical / electrical devices without human intervention, observation, effort, and / or decision-making.

[0141] It should be understood that any components that are alleged to be coupled may be directly or indirectly coupled or connected. In the case of indirect coupling, an additional component may be located between the two components that are alleged to be coupled.

[0142] In this specification, exemplary embodiments have been presented with respect to a selected set of details. However, those skilled in the art will understand that many other exemplary embodiments, including different selected sets of details, can be practiced. It is intended that the appended claims cover all possible exemplary embodiments.

Claims

1. A device, characterized in that, include: The controller is configured to control the transmission via a distributed coherent radar (DCR) system. A processor configured to process radar signals received by the DCR system; The controller is configured to: A first control signal is generated, the first control signal being configured to provide transmission of a first chirp from a plurality of transmission antennas of a first radar head of the DCR system via the DCR system and to provide transmission of the first chirp from a first predetermined antenna of the first radar head, and to restrict transmission of the first chirp to a second predetermined antenna of a second radar head of the DCR system, wherein the first control signal is configured to provide transmission of the first chirp through the first predetermined antenna in a first predetermined frequency band and through the second predetermined antenna in a second predetermined frequency band, wherein the first predetermined frequency band and the second predetermined frequency band are different from one or more frequency bands that cause the transmission antennas of the first radar head to transmit the first chirp; as well as A second control signal is generated, configured to provide transmission of a second chirp from multiple transmission antennas of the second radar head via the DCR system after the first chirp, and to provide transmission of the second chirp from a second predetermined antenna of the second radar head, and to restrict transmission of the second chirp to the first predetermined antenna of the first radar head, wherein the second control signal is configured to provide transmission of the second chirp in a third predetermined frequency band via the first predetermined antenna of the first radar head and in a fourth predetermined frequency band via the second predetermined antenna, wherein the third predetermined frequency band and the fourth predetermined frequency band are different from one or more frequency bands that cause the transmission antenna of the second radar head to transmit the second chirp; and The processor is configured to: In response to the generation of the first control signal, a first radar signal is received from the first radar head of the DCR system; In response to the generation of the first control signal, a second radar signal is received from the second radar head of the DCR system; A first phase noise estimate is determined based on a first radar signal comprising a portion of the first radar signal in the second predetermined frequency band and a second radar signal comprising a portion of the second radar signal in the first predetermined frequency band. as well as In response to the generation of the second control signal, a third radar signal is received from the first radar head of the DCR system; In response to the generation of the second control signal, a fourth radar signal is received from the second radar head of the DCR system; A second phase noise estimate is determined based on a component third radar signal that includes a portion of the third radar signal in the fourth predetermined frequency band and a component fourth radar signal that includes a portion of the fourth radar signal in the third predetermined frequency band.

2. The device according to claim 1, characterized in that, The DCR system includes: The first radar head includes: the plurality of transmitting antennas and the first predetermined antenna, the plurality of transmitting antennas and the first predetermined antenna being configured to provide a transmission chirp; and a plurality of receiving antennas configured to receive one or more reflected signals including the chirp and to generate at least a first radar signal and the third radar signal based on the received signals, wherein the first radar head provides the transmission of the chirp and the reception of the signals based on a first time reference; and The second radar head has: the plurality of transmitting antennas and the second predetermined antenna, the plurality of transmitting antennas and the second predetermined antenna being configured to provide a transmitting chirp; and a plurality of receiving antennas being configured to receive one or more reflected signals including the chirp and to generate at least a second radar signal and the fourth radar signal based on the received signals, wherein the second radar head provides the transmitting chirp and the receiving signals based on a second different time reference.

3. The device according to claim 2, characterized in that, The first predetermined antenna of the first radar head includes a single transmit-receive antenna configured to transmit a corresponding chirp and simultaneously receive one or more reflected signals including the chirp for processing by the processor; and The second predetermined antenna of the second radar head includes a single transmit-receive antenna configured to transmit the corresponding chirp and simultaneously receive the signal including the one or more reflections of the chirp for processing by the processor.

4. The device according to claim 3, characterized in that, The first control signal is configured to provide the first chirp to be transmitted via the DCR system from the first predetermined antenna of the first radar head and the second predetermined antenna of the second radar head at a power lower than the power transmitted by each of the plurality of transmission antennas for the first radar head. and The second control signal is configured to provide the second chirp to be transmitted via the DCR system from the first predetermined antenna of the first radar head and the second predetermined antenna of the second radar head at a power lower than the power transmitted by each of the plurality of transmission antennas for the second radar head.

5. The device according to any one of the preceding claims, characterized in that, The controller is configured to generate a transmission control signal including the first control signal and the second control signal, the transmission control signal being configured to transmit a chirp based on a Doppler diversity multiple access waveform from the plurality of transmission antennas of the first head and the plurality of transmission antennas of the second head.

6. The device according to any one of the preceding claims, characterized in that, The processor is configured to downconvert the first radar signal and the third radar signal from the first radar head to the intermediate frequency range, and to downconvert the second radar signal and the fourth radar signal from the second radar head to the intermediate frequency range.

7. The device according to claim 6, characterized in that, The device includes one or more phase rotators configured such that the component second radar signal and the component third radar signal are located in the middle and / or at the upper and lower ends of the intermediate frequency range.

8. The device according to claim 5, characterized in that, The transmission control signal is configured such that each of the plurality of transmission antennas of the first radar head and each of the plurality of transmission antennas of the second radar head are configured to transmit each chirp with a predetermined phase change. and The processor is configured to provide a phase shift to each chirp that reverses the predetermined phase change.

9. A method for operating a distributed coherent radar (DCR) system, characterized in that, include: A first control signal is generated, the first control signal being configured to provide transmission of a first chirp from a plurality of transmission antennas of a first radar head of the DCR system via the DCR system and to provide transmission of the first chirp from a first predetermined antenna of the first radar head, and to restrict transmission of the first chirp to a second predetermined antenna of a second radar head of the DCR system, wherein the first control signal is configured to provide transmission of the first chirp through the first predetermined antenna in a first predetermined frequency band and through the second predetermined antenna in a second predetermined frequency band, wherein the first predetermined frequency band and the second predetermined frequency band are different from one or more frequency bands that cause the transmission antennas of the first radar head to transmit the first chirp; In response to the generation of the first control signal, a first radar signal is received from the first radar head of the DCR system; In response to the generation of the first control signal, a second radar signal is received from the second radar head of the DCR system; A first phase noise estimate is determined based on a first radar signal comprising a component of the first radar signal in the second predetermined frequency band and a component of the second radar signal comprising a component of the second radar signal in the first predetermined frequency band. A second control signal is generated, the second control signal being configured to provide transmission of a second chirp from a plurality of transmission antennas of the second radar head after the first chirp via the DCR system, and to provide transmission of the second chirp from a second predetermined antenna of the second radar head, and to restrict transmission of the second chirp to the first predetermined antenna of the first radar head, wherein the second control signal is configured to provide transmission of the second chirp in a third predetermined frequency band via the first predetermined antenna of the first radar head and in a fourth predetermined frequency band via the second predetermined antenna, wherein the third predetermined frequency band and the fourth predetermined frequency band are different from one or more frequency bands that cause the transmission antenna of the second radar head to transmit the second chirp; In response to the generation of the second control signal, a third radar signal is received from the first radar head of the DCR system; In response to the generation of the second control signal, a fourth radar signal is received from the second radar head of the DCR system; as well as The second phase noise estimate is determined based on the components of the third radar signal that include a portion of the third radar signal in the fourth predetermined frequency band and the components of the fourth radar signal that include a portion of the fourth radar signal in the third predetermined frequency band.

10. The method according to claim 9, characterized in that, The method includes: Receiving the first radar signal and the third radar signal from the first radar head of the DCR system includes receiving from the first predetermined antenna; Receiving the second radar signal and the fourth radar signal from the second radar head of the DCR system includes receiving them from the second predetermined antenna.

Images