A distributed radar

Abstract

The embodiment of the present application discloses a distributed radar, which can be applied to the fields of intelligent driving, vehicle-mounted radar, etc., and is used to realize the time synchronization requirements of each transmitting antenna. The distributed radar includes a control unit, a receiving antenna and N transmitting antennas, the N transmitting antennas include a first transmitting antenna, a second transmitting antenna and a third transmitting antenna, the distance between the first transmitting antenna and the control unit is less than the distance between the other transmitting antennas and the control unit; there is a first distance between the first transmitting antenna and the second transmitting antenna, there is a second distance between the first transmitting antenna and the third transmitting antenna, and the first distance is less than the second distance; the second transmitting antenna is connected to the control unit through a first cable, and the third transmitting antenna is connected to the control unit through a second cable, the ratio of the first distance to the second distance is a first ratio, the ratio of the length of the first cable to the length of the second cable is a second ratio, and the second ratio is greater than the first ratio.

Description

Technical Field

[0001] The present application relates to the field of radar antennas, and in particular to a distributed radar. Background Art

[0002] As the demand and level of autonomous driving continue to increase, vehicle-mounted millimeter-wave radars are required to provide higher distance and angle resolution when sensing the surrounding environment. Distributed multiple input multiple output (MIMO) radars operating in the submillimeter wave or terahertz frequency bands can meet this demand well.

[0003] Distributed MIMO radars have multiple antennas with a certain distance between them. Antennas that are far from the control unit need to be connected to the control unit via cables. In addition to the different transmission delays of different antennas on the spatial path, the signal transmission in the cable will also produce additional transmission delays, resulting in the antennas in the distributed MIMO radar being unable to meet the time synchronization requirements. Summary of the invention

[0004] The present application provides a distributed radar, which ensures the accuracy of delay estimation to meet the time synchronization requirements of each transmitting antenna.

[0005] In a first aspect, an embodiment of the present application provides a distributed radar, including: a control unit, a receiving antenna and N transmitting antennas, N is an integer greater than or equal to 3, the N transmitting antennas include a first transmitting antenna, a second transmitting antenna and a third transmitting antenna, the distance between the first transmitting antenna and the control unit is less than the distance between other transmitting antennas and the control unit, the distance between the first transmitting antenna and the second transmitting antenna is a first distance, the distance between the first transmitting antenna and the third transmitting antenna is a second distance, the first distance is less than the second distance, the second transmitting antenna is connected to the control unit through a first cable, and the third transmitting antenna is connected to the control unit through a second cable, wherein the ratio of the first distance to the second distance is a first ratio, the ratio of the length of the first cable to the length of the second cable is a second ratio, and the second ratio is greater than the first ratio.

[0006] In this embodiment, when using reflectors for synchronization estimation, since the second ratio is greater than the first ratio, the transmission delay of the signal in the cable and the transmission delay of the signal in the spatial path can be separated in the estimation, thereby ensuring the accuracy of the delay estimation to achieve the time synchronization requirements of each transmitting antenna.

[0007] Optionally, in some possible implementations, the second ratio is greater than the product of the first ratio and 1.5, and the second ratio is less than the product of the reciprocal of the first ratio and 10. In this implementation, a preferred value range of the ratio of the first cable length to the second cable length is provided, further ensuring the accuracy of the delay estimation.

[0008] Optionally, in some possible implementations, the length of the first cable is greater than the length of the second cable.

[0009] Optionally, in some possible implementations, the N transmitting antennas further include a fourth transmitting antenna, the distance between the first transmitting antenna and the fourth transmitting antenna is a third distance, the second distance is less than the third distance, the fourth transmitting antenna is connected to the control unit via a third cable, the ratio of the first distance to the third distance is a third ratio, the ratio of the length of the first cable to the length of the third cable is a fourth ratio, and the fourth ratio is greater than the third ratio. In this implementation, the number of remote transmitting antennas in the distributed radar can also be more than 2, so that the scalability of this solution is higher.

[0010] Optionally, in some possible implementations, the receiving antenna, the first transmitting antenna and the control unit are integrated together, thereby improving the feasibility of the solution.

[0011] Optionally, in some possible implementations, the first cable and the second cable are terahertz active cables (TAC), and a distributed radar operating in a submillimeter wave or terahertz frequency band can provide higher angular resolution.

[0012] Optionally, in some possible implementations, the control unit is used to:

[0013] First, the first transmitting antenna is controlled to transmit a first signal with a first frequency and a second signal with a second frequency, the second transmitting antenna is controlled to transmit a third signal with a first frequency and a fourth signal with a second frequency, and the third transmitting antenna is controlled to transmit a fifth signal with a first frequency and a sixth signal with a second frequency. Afterwards, the echo signal corresponding to each transmitting signal is received through the receiving antenna, specifically including the first echo signal of the first signal, the second echo signal of the second signal, the third echo signal of the third signal, the fourth echo signal of the fourth signal, the fifth echo signal of the fifth signal, and the sixth echo signal of the sixth signal. Next, the phase difference corresponding to the transceiver delay between each transmitting signal and each corresponding echo signal is calculated, specifically including the first phase difference corresponding to the transceiver delay between the first signal and the first echo signal, the second phase difference corresponding to the transceiver delay between the second signal and the second echo signal, the third phase difference corresponding to the transceiver delay between the third signal and the third echo signal, the fourth phase difference corresponding to the transceiver delay between the fourth signal and the fourth echo signal, the fifth phase difference corresponding to the transceiver delay between the fifth signal and the fifth echo signal, and the sixth phase difference corresponding to the transceiver delay between the sixth signal and the sixth echo signal. Furthermore, according to the obtained phase difference set (including the first phase difference, the second phase difference, the third phase difference, the fourth phase difference, the fifth phase difference and the sixth phase difference), a first delay of the signal transmitted through the first cable and a second delay of the signal transmitted through the second cable are calculated.

[0014] In this implementation, a specific implementation method for delay estimation is provided, which improves the practicability of the solution.

[0015] Optionally, in some possible implementations, the control unit includes a signal source, a signal separator and a processor.

[0016] The signal source is used to send a first signal, a second signal, a third signal, a fourth signal, a fifth signal and a sixth signal to the signal separator and the processor.

[0017] The signal separator is used to send the first signal and the second signal to the first transmitting antenna, send the third signal and the fourth signal to the second transmitting antenna, and send the fifth signal and the sixth signal to the third transmitting antenna.

[0018] The processor is used to obtain an echo signal corresponding to each transmitted signal from the receiving antenna, specifically including a first echo signal, a second echo signal, a third echo signal, a fourth echo signal, a fifth echo signal, and a sixth echo signal. Afterwards, the phase difference corresponding to the transmit and receive delay between each transmitted signal and each corresponding echo signal is calculated, specifically including a first phase difference, a second phase difference, a third phase difference, a fourth phase difference, a fifth phase difference, and a sixth phase difference. Furthermore, according to the obtained phase difference set (including the first phase difference, the second phase difference, the third phase difference, the fourth phase difference, the fifth phase difference, and the sixth phase difference), the first delay and the second delay are calculated.

[0019] In this implementation, the implementation method of delay estimation is introduced in combination with the internal structure of the control unit, which further improves the feasibility of this solution.

[0020] Optionally, in some possible implementations, the first cable and the second cable are TACs, and the control unit is further configured to:

[0021] First, the first transmitting antenna is controlled to transmit the seventh signal with the third frequency, the second transmitting antenna is controlled to transmit the eighth signal with the third frequency, and the third transmitting antenna is controlled to transmit the ninth signal with the third frequency. After that, the seventh echo signal of the seventh signal, the eighth echo signal of the eighth signal, and the ninth echo signal of the ninth signal are received through the receiving antenna. Then, the seventh phase difference corresponding to the transceiver delay between the seventh signal and the seventh echo signal, the eighth phase difference corresponding to the transceiver delay between the eighth signal and the eighth echo signal, and the ninth phase difference corresponding to the transceiver delay between the ninth signal and the ninth echo signal are calculated.

[0022] The control unit is also used to:

[0023] A first frequency sweep slope change amount of a signal transmitted through the first cable and a second frequency sweep slope change amount of a signal transmitted through the second cable are calculated according to the phase difference set, the seventh phase difference, the eighth phase difference and the ninth phase difference.

[0024] In this embodiment, a method for calculating a frequency sweep slope variation is provided. The change in the frequency sweep slope of a radar signal can be compensated according to the calculated frequency sweep slope variation, thereby reducing the influence of TAC dispersion on the frequency of the radar signal.

[0025] Optionally, in some possible implementations, the control unit is further configured to:

[0026] First, a first detection signal and a second detection signal are generated. After that, the first detection signal is delayed compensated according to the first delay to obtain a first transmission time, and the second detection signal is delayed compensated according to the second delay to obtain a second transmission time. Furthermore, the second transmitting antenna is controlled to transmit the first detection signal at the first transmission time, and the third transmitting antenna is controlled to transmit the second detection signal at the second transmission time. It should be understood that the above-mentioned first detection signal and the second detection signal are signals transmitted when the radar antenna is in the formal working state.

[0027] In this implementation, when the radar is officially working, delay compensation can be performed on different remote transmitting antennas according to the delay estimation result. Specifically, delay compensation can be performed before the detection signal is transmitted to achieve time synchronization of each transmitting antenna.

[0028] Optionally, in some possible implementations, the control unit is further configured to:

[0029] First, the second transmitting antenna is controlled to transmit the first detection signal, and the third transmitting antenna is controlled to transmit the second detection signal. After that, the first detection echo signal of the first detection signal and the second detection echo signal of the second detection signal are received by the receiving antenna. Then, the first detection echo signal is delayed compensated according to the first delay, and the second detection echo signal is delayed compensated according to the second delay. It should be understood that the above-mentioned first detection signal and the second detection signal are signals transmitted when the radar antenna is in a formal working state.

[0030] In this embodiment, another implementation of delay compensation is provided. Specifically, delay compensation can be performed after receiving the echo signal of the detection signal, thereby improving the flexibility of the solution.

[0031] Optionally, in some possible implementations, the signal transmitted by each transmitting antenna is a sine wave signal or a narrowband amplitude modulated signal. It should be understood that this specifically refers to the test signal for delay estimation transmitted by the antenna being a sine wave signal or a narrowband amplitude modulated signal.

[0032] In a second aspect, an embodiment of the present application provides a distributed radar, including: a control unit, a transmitting antenna and N receiving antennas, N is an integer greater than or equal to 3, the N receiving antennas include a first receiving antenna, a second receiving antenna and a third receiving antenna, the distance between the first receiving antenna and the control unit is less than the distance between other receiving antennas and the control unit, the distance between the first receiving antenna and the second receiving antenna is a first distance, the distance between the first receiving antenna and the third receiving antenna is a second distance, the first distance is less than the second distance, the second receiving antenna is connected to the control unit through a first cable, the third receiving antenna is connected to the control unit through a second cable, the ratio of the first distance to the second distance is a first ratio, the ratio of the length of the first cable to the length of the second cable is a second ratio, and the second ratio is greater than the first ratio.

[0033] Optionally, in some possible implementations, the second ratio is greater than a product of the first ratio and 1.5, and the second ratio is less than a product of the reciprocal of the first ratio and 10.

[0034] Optionally, in some possible implementations, the length of the first cable is greater than the length of the second cable.

[0035] Optionally, in some possible embodiments, the N receiving antennas also include a fourth receiving antenna, the distance between the first receiving antenna and the fourth receiving antenna is a third distance, the second distance is less than the third distance, the fourth receiving antenna is connected to the control unit via a third cable, the ratio of the first distance to the third distance is a third ratio, the ratio of the length of the first cable to the length of the third cable is a fourth ratio, and the fourth ratio is greater than the third ratio.

[0036] Optionally, in some possible implementations, the transmitting antenna, the first receiving antenna and the control unit are integrated together.

[0037] Optionally, in some possible implementations, the first cable and the second cable are TACs.

[0038] Optionally, in some possible implementations, the control unit is used to:

[0039] First, the transmitting antenna is controlled to transmit a first signal having a first frequency and a second signal having a second frequency. Afterwards, the echo signal corresponding to each transmitting signal is received by the first receiving antenna, the second receiving antenna and the third receiving antenna, specifically, the first echo signal of the first signal and the second echo signal of the second signal are received by the first receiving antenna, the third echo signal of the first signal and the fourth echo signal of the second signal are received by the second receiving antenna, and the fifth echo signal of the first signal and the sixth echo signal of the second signal are received by the third receiving antenna. Next, the phase difference corresponding to the transceiver delay between each transmitting signal and each corresponding echo signal is calculated, specifically including the first phase difference corresponding to the transceiver delay between the first signal and the first echo signal, the second phase difference corresponding to the transceiver delay between the second signal and the second echo signal, the third phase difference corresponding to the transceiver delay between the first signal and the third echo signal, the fourth phase difference corresponding to the transceiver delay between the second signal and the fourth echo signal, the fifth phase difference corresponding to the transceiver delay between the first signal and the fifth echo signal, and the sixth phase difference corresponding to the transceiver delay between the second signal and the sixth echo signal. Furthermore, according to the obtained phase difference set (including the first phase difference, the second phase difference, the third phase difference, the fourth phase difference, the fifth phase difference and the sixth phase difference), a first delay of the signal transmitted through the first cable and a second delay of the signal transmitted through the second cable are calculated.

[0040] Optionally, in some possible implementations, the control unit includes a signal source, a signal selector, and a processor.

[0041] The signal source is used to send a first signal and a second signal to a transmitting antenna and a processor.

[0042] The signal selector is used to obtain the echo signal corresponding to each transmission signal from the first receiving antenna, the second receiving antenna and the third receiving antenna, specifically, to obtain the first echo signal and the second echo signal from the first receiving antenna, to obtain the third echo signal and the fourth echo signal from the second receiving antenna, and to obtain the fifth echo signal and the sixth echo signal from the third receiving antenna. After that, the first echo signal, the second echo signal, the third echo signal, the fourth echo signal, the fifth echo signal and the sixth echo signal are sent to the processor.

[0043] The processor is used to calculate the phase difference corresponding to the transmission and reception delay between each transmission signal and each corresponding echo signal, specifically including the first phase difference, the second phase difference, the third phase difference, the fourth phase difference, the fifth phase difference and the sixth phase difference. Afterwards, the first delay and the second delay are calculated according to the obtained phase difference set (including the first phase difference, the second phase difference, the third phase difference, the fourth phase difference, the fifth phase difference and the sixth phase difference).

[0044] Optionally, in some possible implementations, a cable connecting the control unit and each remote receiving antenna is a TAC, and the control unit is further configured to:

[0045] First, the transmitting antenna is controlled to transmit a third signal having a third frequency. Then, the seventh echo signal of the third signal is received by the first receiving antenna, the eighth echo signal of the third signal is received by the second receiving antenna, and the ninth echo signal of the third signal is received by the third receiving antenna. Furthermore, the seventh phase difference corresponding to the transceiver delay between the third signal and the seventh echo signal, the eighth phase difference corresponding to the transceiver delay between the third signal and the eighth echo signal, and the ninth phase difference corresponding to the transceiver delay between the third signal and the ninth echo signal are calculated.

[0046] The control unit is also used to:

[0047] A first frequency sweep slope change amount of a signal transmitted through the first cable and a second frequency sweep slope change amount of a signal transmitted through the second cable are calculated according to the phase difference set, the seventh phase difference, the eighth phase difference and the ninth phase difference.

[0048] Optionally, in some possible implementations, the control unit is further configured to:

[0049] First, the transmitting antenna is controlled to transmit a detection signal. Then, the first detection echo signal of the detection signal is received by the second receiving antenna, and the second detection echo signal of the detection signal is received by the third receiving antenna. Then, the first detection echo signal is delayed compensated according to the first delay, and the second detection echo signal is delayed compensated according to the second delay. It should be understood that the above-mentioned first detection signal and the second detection signal are signals transmitted when the radar antenna is in a formal working state.

[0050] Optionally, in some possible implementations, the signal transmitted by the transmitting antenna is a sine wave signal or a narrowband amplitude modulated signal. It should be understood that this specifically refers to the test signal for delay estimation transmitted by the antenna being a sine wave signal or a narrowband amplitude modulated signal.

[0051] In a third aspect, the present application provides a distributed radar, including: a control unit, a receiving antenna, a first transmitting antenna and a second transmitting antenna, wherein the distance between the first transmitting antenna and the control unit is less than the distance between the second transmitting antenna and the control unit, the second transmitting antenna is connected to the control unit via a cable, and the control unit includes a signal source, a signal separator and a processor;

[0052] The signal source is used to send a first signal with a first frequency, a second signal with a second frequency, a third signal with the first frequency and a fourth signal with the second frequency to the signal separator.

[0053] The signal separator is used to send the first signal and the second signal to the first transmitting antenna, and send the third signal and the fourth signal to the second transmitting antenna.

[0054] The processor is used to: obtain a first echo signal of a first signal, a second echo signal of a second signal, a third echo signal of a third signal, and a fourth echo signal of a fourth signal from a receiving antenna. Calculate a first phase difference corresponding to a transceiver delay between the first signal and the first echo signal, a second phase difference corresponding to a transceiver delay between the second signal and the second echo signal, a third phase difference corresponding to a transceiver delay between the third signal and the third echo signal, and a fourth phase difference corresponding to a transceiver delay between the fourth signal and the fourth echo signal. Calculate the delay of the signal transmitted through the cable according to the first phase difference, the second phase difference, the third phase difference, and the fourth phase difference.

[0055] Optionally, in some possible implementations, the control unit is used to:

[0056] The first transmitting antenna is controlled to transmit a first signal having a first frequency and a second signal having a second frequency, and the second transmitting antenna is controlled to transmit a third signal having a first frequency and a fourth signal having a second frequency. A first echo signal of the first signal, a second echo signal of the second signal, a third echo signal of the third signal, and a fourth echo signal of the fourth signal are received through a receiving antenna. A first phase difference corresponding to the transceiver delay between the first signal and the first echo signal, a second phase difference corresponding to the transceiver delay between the second signal and the second echo signal, a third phase difference corresponding to the transceiver delay between the third signal and the third echo signal, and a fourth phase difference corresponding to the transceiver delay between the fourth signal and the fourth echo signal are calculated. The delay of the signal transmitted through the cable is calculated based on the first phase difference, the second phase difference, the third phase difference, and the fourth phase difference.

[0057] Optionally, in some possible implementations, the cable is a TAC, and the control unit is further configured to:

[0058] The first transmitting antenna is controlled to transmit a fifth signal having a third frequency, and the second transmitting antenna is controlled to transmit a sixth signal having the third frequency. A fifth echo signal of the fifth signal and a sixth echo signal of the sixth signal are received through a receiving antenna. A fifth phase difference corresponding to a transceiver delay between the fifth signal and the fifth echo signal and a sixth phase difference corresponding to a transceiver delay between the sixth signal and the sixth echo signal are calculated.

[0059] The control unit is also used to:

[0060] The change in the frequency sweep slope of the signal transmitted through the cable is calculated according to the first phase difference, the second phase difference, the third phase difference, the fourth phase difference, the fifth phase difference and the sixth phase difference.

[0061] Optionally, in some possible implementations, the receiving antenna, the first transmitting antenna and the control unit are integrated together.

[0062] In an embodiment of the present application, the transmitting antenna of the distributed radar includes a proximal transmitting antenna close to the control unit, and a distal transmitting antenna connected to the control unit via a cable. The ratio of the distances between any two distal transmitting antennas and the proximal transmitting antenna is a first ratio, and the ratio of the lengths of the cables connecting the two transmitting antennas is a second ratio, and the second ratio is greater than the first ratio. It should be understood that when using reflectors for synchronization estimation, since the second ratio is greater than the first ratio, the transmission delay of the signal in the cable and the transmission delay of the signal in the spatial path can be separated in the estimation, ensuring the accuracy of the delay estimation to achieve the time synchronization requirements of each transmitting antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a schematic diagram of a vehicle-mounted distributed radar;

[0064] Figure 2 This is a schematic diagram of the structure of the first distributed radar in this application;

[0065] Figure 3 A schematic diagram of a delay estimation method provided by the present application;

[0066] Figure 4 This is a schematic diagram of an embodiment of the first method of calculating the phase difference corresponding to the transmission and reception delay in the present application;

[0067] Figure 5 This is a waveform diagram of the first transmission signal in this application;

[0068] Figure 6 This is a schematic diagram of an embodiment of the second method of calculating the phase difference corresponding to the transmission and reception delay in the present application;

[0069] Figure 7 This is a waveform diagram of the second transmission signal in this application;

[0070] Figure 8 This is a schematic diagram of the structure of the second distributed radar in this application;

[0071] Fig. 9 Schematic diagram of the effect of TAC dispersion on radar signal frequency;

[0072] Fig.10 This is a schematic diagram of the structure of the third distributed radar in this application;

[0073] Fig.11 This is a schematic diagram of the structure of the fourth distributed radar in this application;

[0074] Fig.12 A schematic diagram of a delay estimation method provided by the present application;

[0075] Fig.13 This is a schematic diagram of the structure of the fifth distributed radar in this application. DETAILED DESCRIPTION

[0076] The embodiment of the present application provides a distributed radar, and the transmission delay of the signal in the cable and the transmission delay of the signal in the space path can be separated in estimation, ensuring the accuracy of the delay estimation to achieve the time synchronization requirements of each transmitting antenna. The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described here can be implemented in an order other than that illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0077] The distributed radar provided in this application refers to a radar in which multiple transmitting antennas or receiving antennas are distributed in space, and each antenna is uniformly controlled by a control unit. Among them, the distributed radar can be applied to multiple fields such as automobile assisted driving, atmospheric detection, remote measurement and remote sensing. The following is a further introduction using the distributed radar applied to the vehicle-mounted scene as an example.

[0078] Figure 1 This is a schematic diagram of a vehicle-mounted distributed radar. Distributed radar can install multiple radar antennas (including transmitting antennas and receiving antennas) dispersedly on the vehicle body, and use virtual aperture synthesis technology to achieve extremely high angular resolution, avoiding the problem of limited radar size in a single installation location in vehicle-mounted scenarios. In addition, the distributed radar can operate in the submillimeter wave or terahertz frequency band, thereby being able to produce a narrower beam at the same aperture, allowing the distributed radar to provide higher angular resolution when sensing the surrounding environment.

[0079] like Figure 1 As shown, there are several remote transmitting antennas (TX) in the distributed radar, which are connected to the control processing unit through cables, among which two virtual receiving antennas (RX) are virtual receiving antennas constructed by data of the two remote transmitting antennas when the virtual aperture is constructed using multiple input multiple output (MIMO) radar technology.

[0080] Since the distant radar antennas are connected to the control unit via cables, in addition to the different transmission delays on the spatial path, the signal transmission in the cable will also produce additional transmission delays, resulting in the radar antennas in the distributed radar being unable to meet the time synchronization requirements.

[0081] Therefore, to achieve time synchronization of distributed radars, it is necessary to accurately estimate the transmission delay of the signal transmitted by each radar antenna. To this end, the present application provides a distributed radar to ensure the accuracy of delay estimation, which is described in detail below.

[0082] It should be noted that, for the sake of ease of introduction, the transmitting antennas in the distributed radar that are connected to the control unit through cables are collectively referred to as remote transmitting antennas, and the transmitting antennas whose distance to the control unit is less than the distance between each remote transmitting antenna and the control unit are referred to as near-end transmitting antennas.

[0083] Figure 2 It is a structural diagram of the first distributed radar in this application. The distributed radar includes: a control unit 10, a receiving antenna 30 and N transmitting antennas 201-20N, where N is an integer greater than or equal to 3. Among them, the positions of the N transmitting antennas in space are different, and the N transmitting antennas include a near-end transmitting antenna 201 and a plurality of far-end transmitting antennas 202-20N. It can be understood that the near-end transmitting antenna 201 is arranged at a position close to the control unit 10, that is, the distance between the near-end transmitting antenna 201 and the control unit 10 is less than the distance between each far-end transmitting antenna and the control unit 10. Specifically, the near-end transmitting antenna 201 can be integrated with the control unit 10. The receiving antenna 30 can be integrated with the control unit 10, or it can be connected to the control unit 10 through a cable, which is not limited here. Multiple far-end transmitting antennas 202-20N are respectively connected to the control unit 10 through corresponding cables. For example, the far-end transmitting antenna 202 is connected to the control unit 10 through the cable L1, and the far-end transmitting antenna 203 is connected to the control unit 10 through the cable L2, and so on. The spatial distance between the near-end transmitting antenna 201 and the far-end transmitting antenna 202 is recorded as Δx1, the spatial distance between the near-end transmitting antenna 201 and the far-end transmitting antenna 203 is recorded as Δx2, and so on. The spatial distance between the near-end transmitting antenna 201 and the far-end transmitting antenna 20N is recorded as ΔxN-1.

[0084] It should be understood that in this embodiment, the number of receiving antennas 30 is not limited to one, and multiple receiving antennas may be distributed in space, and the specific number is not limited here. In addition, the receiving antenna 30 and each transmitting antenna may be a single antenna structure or an antenna array structure, which is not specifically limited here.

[0085] It should be noted that the echo signal of the signal transmitted by each transmitting antenna after being reflected by the reflector is received by the receiving antenna. Since different transmitting antennas have different positions in space and are connected to the control unit through cables of different lengths, the transmission and reception delays of the signals transmitted by different transmitting antennas include the transmission delay in the cable and the transmission delay in the spatial path. When performing delay estimation, if the distance between different remote transmitting antennas and the proximal transmitting antennas and their corresponding cable lengths are in the same ratio (for example, L1 / L2=△x1 / △x2), the transmission delay in the cable and the transmission delay in the spatial path can no longer be separated mathematically, resulting in a large estimation error. Therefore, in this application, the cable lengths corresponding to any two remote transmitting antennas need to meet the following conditions. Taking L1 and L2 as an example, under the premise of L1<L2, L1 / L2>△x1 / △x2 must be satisfied. In one possible implementation, in order to further ensure the accuracy of the delay estimation, 1.5*△x1 / △x2<L1 / L2<10*△x2 / △x1. In another possible implementation, in the matrix When the condition number is the smallest, the error of delay estimation is the smallest and the value of L1 / L2 is optimal. For example, when △x2 / △x1=2 and the length of L2 is close to △x2, the optimal value of L1 / L2 is approximately 2.

[0086] The following is combined with the above Figure 2 The distributed radar shown introduces the delay estimation method provided by the present application, specifically, taking N transmitting antennas including a near-end transmitting antenna 201, a far-end transmitting antenna 202 and a far-end transmitting antenna 203 as an example for explanation. Figure 3 This is a schematic diagram of a delay estimation method provided in the present application. The delay estimation method is executed by a control unit 10 and specifically includes the following steps:

[0087] 301. Control a near-end transmitting antenna to transmit a first signal of frequency f1 and a second signal of frequency f2, control a far-end transmitting antenna to transmit a third signal of frequency f1 and a fourth signal of frequency f2, and control a far-end transmitting antenna to transmit a fifth signal of frequency f1 and a sixth signal of frequency f2.

[0088] It is understandable that the near-end transmitting antenna 201, the far-end transmitting antenna 202 and the far-end transmitting antenna 203 all transmit the signals of frequency f1 and frequency f2 in a time-sharing manner. In addition, the control unit 10 may first control one of the transmitting antennas to transmit the signals of frequency f1 and frequency f2, and then control another transmitting antenna to transmit the signals of frequency f1 and frequency f2. The specific transmission order is not limited here.

[0089] 302. Receive an echo signal corresponding to each transmitted signal through a receiving antenna.

[0090] Specifically, the echo signals include a first echo signal of the first signal, a second echo signal of the second signal, a third echo signal of the third signal, a fourth echo signal of the fourth signal, a fifth echo signal of the fifth signal, and a sixth echo signal of the sixth signal.

[0091] 303. Calculate a phase difference corresponding to a transmission / reception delay between each transmission signal and each corresponding echo signal.

[0092] Specifically, it includes a first phase difference, a second phase difference, a third phase difference, a fourth phase difference, a fifth phase difference and a sixth phase difference. The first phase difference is a phase difference corresponding to a transceiver delay between the first signal and the first echo signal, the second phase difference is a phase difference corresponding to a transceiver delay between the second signal and the second echo signal, the third phase difference is a phase difference corresponding to a transceiver delay between the third signal and the third echo signal, the fourth phase difference is a phase difference corresponding to a transceiver delay between the fourth signal and the fourth echo signal, the fifth phase difference is a phase difference corresponding to a transceiver delay between the fifth signal and the fifth echo signal, and the sixth phase difference is a phase difference corresponding to a transceiver delay between the sixth signal and the sixth echo signal.

[0093] Optionally, the present application provides multiple methods for calculating the phase difference corresponding to the transmission and reception delays, which are introduced below respectively.

[0094] The first one calculates the phase difference by cycle counting and phase detection.

[0095] Figure 4 FIG. 1 is a schematic diagram of an embodiment of calculating the phase difference corresponding to the transmission and reception delay in the first embodiment of the present application. It can be understood that the processor in the control unit 10 includes: Figure 4 The structure of the cycle counter and phase detector is shown. Figure 5 The waveform diagram of the first transmission signal in this application is shown in FIG. The signal transmitted by the transmitting antenna is a sine wave signal, and its waveform can be as follows: Figure 5 As shown. Specifically, when the transmitting antenna transmits a signal, the cycle counter detects the transmitted signal and starts counting. Each waveform cycle counter is incremented by 1. After the cycle counter detects the echo signal, the counting stops and the count value N is output. In addition, the transmitted signal and the echo signal are simultaneously input into a phase detector for phase detection. The phase detector compares the waveforms of the transmitted and received signals in the same period of time and outputs the phase difference δ between the two. Finally, the phase difference φ corresponding to the transmit and receive delay is calculated based on the output of the cycle counter and the output of the phase detector. For example, the starting time of the echo signal lags behind the transmitted signal by N complete sinusoidal cycles, and the continuous wave phase of the echo signal lags behind the continuous wave phase of the transmitted signal by δ, then the phase difference φ corresponding to the transmit and receive delay is 2πN+δ.

[0096] The second method is to calculate the phase difference through envelope detection and phase discrimination.

[0097] Figure 6 FIG. 1 is a schematic diagram of an embodiment of calculating the phase difference corresponding to the transmission and reception delay in the second embodiment of the present application. It can be understood that the processor in the control unit 10 includes: Figure 6 The structure of the envelope detector, correlation peak calculation module and phase detector is shown. Figure 7 FIG. 1 is a waveform diagram of the second type of transmitted signal in this application. The signal transmitted by the transmitting antenna is a narrowband amplitude modulated signal, and its waveform can be as follows: Figure 7 The narrowband amplitude modulated signal can be expressed as s(t)=A(t)cos(2πf i t)=sin(2πf 0 t)cos(2πf i t). The center frequency of the narrowband AM signal is f i , A(t) is a fixed low-frequency modulation signal. For example, in this embodiment, A(t) is a sine wave signal with a frequency of 1 MHz, that is, f 0 =1MHz. Specifically, both the transmission signal and the echo signal have an envelope with a low-frequency variation, such as Figure 7 As shown by the dotted line on the waveform. One envelope detector performs envelope detection on the transmission signal, and the other envelope detector performs envelope detection on the echo signal. The two envelope detectors output the low-frequency envelope signal sin(2πf corresponding to the transmission signal and the echo signal respectively. 0 t). Then, the correlation peak calculation module calculates the time domain correlation values ​​of the two low-frequency envelope signals respectively, and determines the time deviation T of the correlation peak. P , you can refer to Figure 7 T P According to T P Determine f i The number of delay cycles of the carrier signal N = P *f i The phase detector calculates the transmission signal and the echo signal at the carrier frequency signal cos(2πf i Finally, the phase difference φ corresponding to the transmit and receive delay is calculated to be 2πN+δ.

[0098] 304. Calculate a first delay of the signal transmitted through the first cable and a second delay of the signal transmitted through the second cable according to the obtained phase difference set.

[0099] The phase difference set includes a first phase difference, a second phase difference, a third phase difference, a fourth phase difference, a fifth phase difference and a sixth phase difference.

[0100] Specifically, the first phase difference and the second phase difference can be expressed as i = 1 or 2. Wherein, t1 represents the near-end transmitting antenna 201. φ t1f1 represents the first phase difference, φt1f2 Represents the second phase difference. c is the speed of electromagnetic waves in free space. i The phase difference corresponding to the transmission and reception delay of the near-end transmitting antenna 201 is mainly caused by the transmission delay of electromagnetic wave signals of different frequencies in space.

[0101] The third phase difference and the fourth phase difference can be expressed as i = 1 or 2. Where t2 represents the remote transmitting antenna 202, φ t2f1 represents the third phase difference, φ t2f2 represents the fourth phase difference. d is an unknown quantity determined by the azimuth of the reflector relative to the near-end transmitting antenna 201 and the far-end transmitting antenna 202, which reflects the electromagnetic wave travel difference corresponding to the near-end transmitting antenna 201 and the far-end transmitting antenna 202 due to the spatial interval Δx1. ω Indicates the speed at which electromagnetic waves propagate in the cable. If there is no dispersion effect in the cable, electromagnetic waves of different frequencies have the same propagation speed. Other parameters have been introduced above and will not be repeated here. It represents the signal phase difference between the near-end transmitting antenna 201 and the far-end transmitting antenna 202 caused by the difference in electromagnetic wave travel distance. Indicates the signal phase difference caused by electromagnetic waves transmitted through the L1 cable.

[0102] The fifth phase difference and the sixth phase difference can be expressed as i = 1 or 2. Where t3 represents the remote transmitting antenna 203, φ t3f1 represents the fifth phase difference, φ t3f2 The other parameters have been introduced above and will not be described here again. It represents the signal phase difference between the near-end transmitting antenna 201 and the far-end transmitting antenna 203 caused by the difference in electromagnetic wave travel distance. Indicates the signal phase difference caused by electromagnetic waves transmitted through the L2 cable.

[0103] After obtaining the above 6 phase differences, the difference between the phase differences of the two frequency points corresponding to each transmitting antenna is further calculated. The specific expression is as follows:

[0104]

[0105]

[0106]

[0107] Among them, θ t1d21θ represents the difference between the second phase difference and the first phase difference corresponding to the near-end transmitting antenna 201. t2d21 θ represents the difference between the fourth phase difference and the third phase difference corresponding to the remote transmitting antenna 202. t3d21 represents the difference between the sixth phase difference and the fifth phase difference corresponding to the remote transmitting antenna 203. Δω represents the angular frequency difference between the signal of frequency f2 and the signal of frequency f1. Since Δω is known, two values ​​N1 and N2 can be obtained by mathematically transforming the difference of the above three sets of phase differences, which are specifically expressed as follows:

[0108]

[0109]

[0110] in, Since the direction of the reflector cannot be detected before the radar is officially operational, d is an unknown quantity. 1 It is also an unknown quantity. 2 It represents the transmission delay of the electromagnetic wave signal with frequency f1 in the cable with length L1. Since the cable length and the speed of electromagnetic wave transmission in the cable are unknown, M 2 It is also an unknown quantity. α is the ratio of the lengths of the two cables L1 and L2. Then the transmission delay of the electromagnetic wave signal with frequency f1 in the cable with length L2 can be expressed as αM 2 .

[0111] It can be understood that, under normal circumstances, M can be calculated based on the above expressions corresponding to N1 and N2. 1 and M 2 However, it can be seen from observation that if That is, when the cable lengths corresponding to the two remote transmitting antennas are proportional to the distances between the two remote transmitting antennas and the near-end transmitting antenna, the expressions corresponding to N1 and N2 above will degenerate into a pair of linearly related equations. At this time, M cannot be calculated in this way. 1 and M 2 Therefore, in order to ensure the accuracy of the estimation, the ratio of L1 to L2 should satisfy the above Figure 2 Ranges given for the embodiments shown.

[0112] It should be noted that after completing the above Figure 3 After the delay estimation described in the illustrated embodiment, when the radar is officially working, delay compensation can be performed on different remote transmitting antennas according to the delay estimation result. There are multiple implementation methods, which are introduced below.

[0113] The first is to perform delay compensation before the radar detection signal is sent.

[0114] Specifically, the generation parameters of the signals transmitted by the remote transmitting antenna 202 and the remote transmitting antenna 203 are modified. For example, when the remote transmitting antenna 202 generates the radar detection signal, the default generation time is advanced by M. 2 When the remote transmitting antenna 203 generates the radar detection signal, it is advanced by αM in the default generation time. 2 .

[0115] The second method is to perform delay compensation after receiving the echo signal of the radar detection signal.

[0116] Specifically, the remote transmitting antenna 202 and the remote transmitting antenna 203 generate and transmit the detection signal according to the default generation parameters. After receiving the echo signal of the signal transmitted by the remote transmitting antenna 202, the control unit subtracts M from the receiving time of the echo signal. 2 After receiving the echo signal of the signal transmitted by the remote transmitting antenna 203, the control unit subtracts αM from the receiving time of the echo signal. 2 .

[0117] The delay estimation method provided in the present application is further described below in conjunction with the internal structure of the control unit 10 . Figure 8 It is a structural diagram of the second distributed radar in the present application. The control unit 10 includes a signal source 101, a signal separator 102 and a processor 103. The signal source 101 is used to generate a signal of a specified frequency (such as the first signal to the sixth signal mentioned above), and send the generated signal to the signal separator 102 and the processor 103. The signal separator 102 is used to send the signal generated by the signal source to different transmitting antennas, for example, the first signal and the second signal are sent to the near-end transmitting antenna 201, the third signal and the fourth signal are sent to the first remote transmitting antenna 202, and the fifth signal and the sixth signal are sent to the second remote transmitting antenna 203. The processor 103 is used to obtain the echo signal of the transmitted signal of each transmitting antenna from the receiving antenna 30 (such as the first echo signal to the sixth echo signal mentioned above), and then calculate the phase difference (such as the first phase difference to the sixth phase difference mentioned above) according to each transmitted signal and the corresponding echo signal, and then calculate the first delay of the signal transmitted through the first cable and the second delay transmitted through the second cable according to the first phase difference to the sixth phase difference. It should be noted that, in addition to the signal source 101 for transmitting the test signal, the control unit 10 may also include a working signal source specifically for transmitting the working signal, and the processor 103 may perform delay compensation on the working signal transmitted by the working signal source according to the delay estimation result. Of course, optionally, both the test signal and the working signal may also be transmitted by the same signal source (e.g. Figure 8 The signal source 101 shown is sent, and the specific details are not limited here.

[0118] From the above description, it can be seen that the transmitting antenna of the distributed radar includes a proximal transmitting antenna close to the control unit and a distal transmitting antenna connected to the control unit via a cable. The cable length corresponding to any two distal transmitting antennas satisfies the condition of L1 / L2>△x1 / △x2, so that the transmission delay of the signal in the cable and the transmission delay of the signal in the spatial path can be separated in the estimation, ensuring the accuracy of the delay estimation to achieve the time synchronization requirements of each transmitting antenna.

[0119] In one possible implementation, a distributed radar operating in the submillimeter wave or terahertz frequency band can provide higher angular resolution. Since terahertz signals can be transmitted directly in plastic waveguides made of polymers, the distributed radar can use a terahertz active cable (TAC) to connect the remote transmitting antenna. However, in addition to the additional transmission delay when the terahertz radar signal is transmitted on the remote cable, the dispersion characteristics of the TAC will also change the sweep slope of the linear frequency modulation (LFM) radar signal.

[0120] Fig. 9 The time-frequency variation of a normally generated LFM radar signal is shown in Figure 1. Fig. 9 As shown in S1 in . Without the influence of dispersion, the signal received by the radar after being reflected by the target is as follows Fig. 9 As shown in S2 in the figure. S1 and S2 have exactly the same sweep slope in the time-frequency domain, that is, they have a fixed frequency difference in the time overlap region. However, after the radar signal is affected by dispersion, the received signal will be distorted, as shown in Fig. 9 As shown in S3 in the figure. At this time, the sweep slope of S3 changes, and S1 and S3 do not have the same sweep slope in the time-frequency domain. The radar will not be able to stably detect the physical information of the target (such as the speed, acceleration, and distance of the target). Therefore, in the implementation method of using TAC as a cable to connect the remote transmitting antenna, in addition to calculating the transmission and reception delay, it is also necessary to calculate the change in the sweep slope. The following is a detailed introduction.

[0121] In the above Figure 3On the basis of the illustrated embodiment, the control unit 10 will also control the near-end transmitting antenna 201 to transmit the seventh signal of the frequency f3, control the first remote transmitting antenna 202 to transmit the eighth signal of the frequency f3, and control the second remote transmitting antenna 203 to transmit the ninth signal of the frequency f3. The control unit 10 will also receive the seventh echo signal of the seventh signal, the eighth echo signal of the eighth signal, and the ninth echo signal of the ninth signal through the receiving antenna 30. The control unit 10 will also calculate the seventh phase difference corresponding to the transceiver delay between the seventh signal and the seventh echo signal, the eighth phase difference corresponding to the transceiver delay between the eighth signal and the eighth echo signal, and the ninth phase difference corresponding to the transceiver delay between the ninth signal and the ninth echo signal. Furthermore, the control unit 10 calculates the first delay and the first frequency sweep slope change of the signal transmitted through the first cable, and the second delay and the second frequency sweep slope change of the signal transmitted through the second cable according to the first phase difference to the ninth phase difference. This calculation process is further described below.

[0122] The first phase difference, the second phase difference and the seventh phase difference can be expressed as i = 1, 2, 3. φ t1f1 represents the first phase difference, φ t1f2 represents the second phase difference, φ t1f3 The parameters in this expression have been introduced above and will not be repeated here.

[0123] The third phase difference, the fourth phase difference and the eighth phase difference can be expressed as i = 1, 2, 3. φ t2f1 represents the third phase difference, φ t2f2 represents the fourth phase difference, φ t2f3 represents the eighth phase difference. It represents the speed of electromagnetic waves with a frequency of fi propagating in TAC medium. Due to the dispersion effect in TAC, electromagnetic waves with different frequencies have different propagation speeds when transmitted in TAC medium. For example, the relationship between the propagation speeds of electromagnetic waves with frequencies of f1 and f2 in TAC medium is The other parameters in the above expression have been introduced above and will not be repeated here.

[0124] The fifth phase difference, the sixth phase difference and the ninth phase difference can be expressed as i = 1, 2, 3. φ t3f1 represents the fifth phase difference, φ t3f2 represents the sixth phase difference, φ t3f3 The parameters in this expression have been introduced above and will not be repeated here.

[0125] After obtaining the above 9 phase differences, the difference between the phase differences of the three frequency points corresponding to each transmitting antenna is further calculated. The specific expression is as follows:

[0126] i=2 or 3

[0127] i=2 or 3

[0128] i=2 or 3

[0129] Among them, θ t1di1 θ represents the difference between the second phase difference and the first phase difference corresponding to the near-end transmitting antenna 201 or the difference between the seventh phase difference and the first phase difference. t2di1 θ represents the difference between the fourth phase difference and the third phase difference corresponding to the remote transmitting antenna 202 or the difference between the eighth phase difference and the third phase difference. t3di1 It represents the difference between the sixth phase difference and the fifth phase difference or the difference between the ninth phase difference and the fifth phase difference corresponding to the remote transmitting antenna 203. Since Δω2 and Δω3 are known, four values ​​N1, N2, N3 and N4 can be obtained after mathematical transformation of the differences of the above 9 groups of phase differences, which are specifically expressed as follows:

[0130]

[0131]

[0132]

[0133]

[0134] in, M 3 =L 1 β, Since the direction of the reflector cannot be detected before the radar is officially operational, d is an unknown quantity. 1 It is also an unknown quantity. 2 It represents the transmission delay of the electromagnetic wave signal with frequency f1 in the TAC cable with length L1. Since the length of the TAC cable and the transmission speed of the electromagnetic wave in the TAC cable are unknown, M 2 It is also an unknown quantity. 3 It indicates the dispersion degree in the TAC cable with a length of L1, that is, M 3 It directly determines the change in the frequency sweep slope of an LFM signal after it is transmitted through a TAC cable with a length of L1. α is the ratio of the lengths of the two cables L1 and L2. Then the transmission delay of the electromagnetic wave signal with a frequency of f1 in a cable with a length of L2 can be expressed as αM 2, the sweep slope change of the LFM signal after being transmitted through the TAC cable with a length of L2 is αM 3 It should be noted that in order to ensure the accuracy of the estimation, the ratio of L1 to L2 should satisfy the above Figure 2 The range given in the embodiment shown in the figure, thus M can be calculated according to the above four expressions of N1-N4 1 、M 2 、M 3 and α.

[0135] It can be seen from the above description that the method for calculating the change in the frequency sweep slope provided in the present application can compensate for the change in the frequency sweep slope of the radar signal, thereby reducing the impact of TAC dispersion on the radar signal frequency.

[0136] It should be noted that the above describes the delay estimation method and the estimation method of the sweep frequency slope change amount by taking N transmitting antennas including the near-end transmitting antenna 201, the far-end transmitting antenna 202 and the far-end transmitting antenna 203 as an example. On this basis, the delay estimation and the estimation of the sweep frequency slope change amount of other more far-end transmitting antennas can be implemented by referring to the calculation method provided above, and the details will not be repeated here.

[0137] In addition, the delay estimation method and the frequency sweep slope variation estimation method provided above are not only applicable to Figure 2 For the distributed radar structure shown in the figure, if the transmitting antenna of the distributed radar only includes a proximal transmitting antenna and a distal transmitting antenna, this structure can also use the above method to perform delay estimation and estimation of the sweep frequency slope change, which is further explained below.

[0138] Fig.10 Schematic diagram of the structure of the third distributed radar in this application. Similar to the above-mentioned method, the near-end transmitting antenna 201 and the far-end transmitting antenna 202 need to transmit the signal of frequency f1, the signal of frequency f2 and the signal of frequency f3 respectively. Then, the three groups of phase differences corresponding to the near-end transmitting antenna 201 and the three groups of phase differences corresponding to the far-end transmitting antenna 202 are calculated. Among them, the three groups of phase differences corresponding to the near-end transmitting antenna 201 can be expressed as i = 1, 2, 3. The three phase differences corresponding to the remote transmitting antenna 202 can be expressed as i=1, 2, 3. Then, for the near-end transmitting antenna 201 and the far-end transmitting antenna 202, the difference between the phase difference corresponding to the signal of frequency f2 and the signal of frequency f3 and the phase difference corresponding to the signal of frequency f1 is calculated respectively. The specific expression is as follows:

[0139] i=2 or 3

[0140] i=2 or 3

[0141] Since Δω2 and Δω3 are known, four values ​​N1 and N2 can be obtained by mathematically transforming the differences of the above six phase differences, which are specifically expressed as follows:

[0142]

[0143]

[0144] in, M 3 =L 1 β, let P = Δx 1 M 1 +M 2 Then, according to the above expressions of N1 and N2, M can be calculated. 3 and P. It should be understood that M 3 It indicates the dispersion degree in the TAC cable with a length of L1, that is, M 3 It directly determines the change in the frequency sweep slope of an LFM signal after it is transmitted through a TAC cable with a length of L1. P represents the transmission delay of the signal transmitted by the far-end transmitting antenna relative to the signal transmitted by the near-end transmitting antenna. M 2 It represents the transmission delay of the electromagnetic wave signal with frequency f1 in the TAC cable with length L1. 1 M 1 represents the transmission delay difference between the near-end transmitting antenna and the far-end transmitting antenna due to the spatial spacing of Δx1. Then, the signal transmitted by the far-end transmitting antenna can be delayed according to P, and according to M 3 Perform frequency sweep slope compensation on the signal transmitted by the remote transmitting antenna.

[0145] The above embodiments are all based on Figure 2 In addition to the "one-receive, multiple-transmit" distributed radar structure shown in the figure, the present application can also adopt a "one-transmit, multiple-receive" distributed radar structure, which is introduced in detail below.

[0146] It should be noted that, for the sake of ease of introduction, the receiving antennas in the distributed radar that are connected to the control unit through cables are collectively referred to as remote receiving antennas, and the receiving antennas whose distance to the control unit is less than the distance between each remote receiving antenna and the control unit are referred to as near-end receiving antennas.

[0147] Fig.11: is a schematic diagram of the structure of the fourth distributed radar in the present application. The distributed radar includes: a control unit 10, a transmitting antenna 20 and N receiving antennas 301-30N, where N is an integer greater than or equal to 3. Among them, the positions of the N receiving antennas in space are different, and the N receiving antennas include a near-end receiving antenna 301 and a plurality of far-end receiving antennas 302-30N. It can be understood that the near-end receiving antenna 301 is arranged at a position close to the control unit 10, that is, the distance between the near-end receiving antenna 301 and the control unit 10 is less than the distance between each far-end receiving antenna and the control unit 10. Specifically, the near-end receiving antenna 301 can be integrated with the control unit 10. The transmitting antenna 20 can be integrated with the control unit 10, or it can be connected to the control unit 10 through a cable, which is not limited here. Multiple far-end receiving antennas 302-30N are respectively connected to the control unit 10 through corresponding cables. For example, the far-end receiving antenna 302 is connected to the control unit 10 through the cable L1, and the far-end receiving antenna 303 is connected to the control unit 10 through the cable L2, and so on. The spatial distance between the near-end receiving antenna 301 and the far-end receiving antenna 302 is recorded as △x1, the spatial distance between the near-end receiving antenna 301 and the far-end receiving antenna 303 is recorded as △x2, and so on. The spatial distance between the near-end receiving antenna 301 and the far-end receiving antenna 30N is recorded as △xN-1.

[0148] It should be noted that Figure 2 Similar to the description of the illustrated embodiment, the cable lengths corresponding to any two remote receiving antennas need to meet the following conditions. Taking L1 and L2 as an example, under the premise of L1<L2, L1 / L2>△x1 / △x2 must be satisfied. In one possible implementation, in order to further ensure the accuracy of delay estimation, 1.5*△x1 / △x2<L1 / L2<10*△x2 / △x1. In another possible implementation, in the matrix When the condition number is the smallest, the error of delay estimation is the smallest and the value of L1 / L2 is optimal. For example, when △x2 / △x1=2 and the length of L2 is similar to △x2, the optimal value of L1 / L2 is approximately 2.

[0149] It should be understood that in this embodiment, the number of transmitting antennas 20 is not limited to one, and multiple transmitting antennas may be distributed in the space, and the specific number is not limited here.

[0150] The following is combined with the above Fig.11 The distributed radar shown introduces the delay estimation method provided by the present application, specifically, N receiving antennas including a near-end receiving antenna 301, a far-end receiving antenna 302 and a far-end receiving antenna 303 are used as an example for explanation. Fig.12This is a schematic diagram of a delay estimation method provided in the present application. The delay estimation method is executed by a control unit 10 and specifically includes the following steps:

[0151] 1201. Control a transmitting antenna to transmit a first signal of a frequency f1 and a second signal of a frequency f2.

[0152] 1202. Receive an echo signal corresponding to each transmitted signal through a near-end receiving antenna and each far-end receiving antenna.

[0153] Specifically, the first echo signal of the first signal and the second echo signal of the second signal are received by the near-end receiving antenna 301, the third echo signal of the first signal and the fourth echo signal of the second signal are received by the far-end receiving antenna 302, and the fifth echo signal of the first signal and the sixth echo signal of the second signal are received by the far-end receiving antenna 303.

[0154] 1203. Calculate the phase difference corresponding to the transmission and reception delay between each transmission signal and each corresponding echo signal.

[0155] Specifically, it includes a first phase difference, a second phase difference, a third phase difference, a fourth phase difference, a fifth phase difference and a sixth phase difference.

[0156] Among them, the first phase difference is the phase difference corresponding to the transceiver delay between the first signal and the first echo signal, the second phase difference is the phase difference corresponding to the transceiver delay between the second signal and the second echo signal, the third phase difference is the phase difference corresponding to the transceiver delay between the first signal and the third echo signal, the fourth phase difference is the phase difference corresponding to the transceiver delay between the second signal and the fourth echo signal, the fifth phase difference is the phase difference corresponding to the transceiver delay between the first signal and the fifth echo signal, and the sixth phase difference is the phase difference corresponding to the transceiver delay between the second signal and the sixth echo signal.

[0157] It should be noted that the calculation method of the above phase difference is the same as Figure 3 The method described in step 303 of the illustrated embodiment is similar and will not be described in detail here.

[0158] 1204. Calculate a first delay of the signal transmitted through the first cable and a second delay of the signal transmitted through the second cable according to the obtained phase difference set.

[0159] The phase difference set includes a first phase difference, a second phase difference, a third phase difference, a fourth phase difference, a fifth phase difference and a sixth phase difference.

[0160] In this embodiment, the calculation method of the first delay and the second delay is the same as Figure 3 The method described in step 304 of the illustrated embodiment is similar and will not be described in detail here.

[0161] The delay estimation method provided in the present application is further described below in conjunction with the internal structure of the control unit 10 . Fig.13 It is a structural diagram of the fifth distributed radar in the present application. The control unit 10 includes a signal source 101, a signal selector 104 and a processor 103. The signal source 101 is used to generate a signal of a specified frequency (such as the first signal and the second signal mentioned above), and send the generated signal to the transmitting antenna 20 and the processor 103. Each receiving antenna is used to receive the echo signal of the first signal and the second signal respectively (such as the first echo signal to the sixth echo signal mentioned above). The signal selector 104 is used to obtain the corresponding echo signal from each receiving antenna, and send each echo signal to the processor 103 in a time-division or parallel manner. For example, the signal selector 104 can send the first echo signal to the sixth echo signal to the processor 103 one by one, or the signal selector 104 can also send multiple or all echo signals to the processor 103 at one time. The processor 103 is used to calculate the phase difference (such as the first phase difference to the sixth phase difference mentioned above) according to each transmitted signal and the corresponding echo signal, and then calculate the first delay of the signal transmitted through the first cable and the second delay transmitted through the second cable according to the first phase difference to the sixth phase difference. It should be noted that, in addition to the signal source 101 for transmitting the test signal, the control unit 10 may also include a working signal source specifically for transmitting the working signal, and the processor 103 may perform delay compensation on the working signal transmitted by the working signal source according to the delay estimation result. Of course, optionally, both the test signal and the working signal may also be transmitted by the same signal source (e.g. Fig.12 The signal source 101 shown is sent, and the specific details are not limited here.

[0162] It is understandable that in the implementation method of using TAC as a cable to connect the remote receiving antenna, in addition to calculating the transmission and reception delay, it is also necessary to calculate the change in the frequency sweep slope. This is described in detail below.

[0163] In the above Fig.12On the basis of the illustrated embodiment, the control unit 10 will also control the transmitting antenna 20 to transmit a third signal of a frequency f3. The control unit 10 will also receive the seventh echo signal of the third signal through the near-end receiving antenna 301, receive the eighth echo signal of the third signal through the first far-end receiving antenna 302, and receive the ninth echo signal of the third signal through the second far-end receiving antenna 303. The control unit 10 will also calculate the seventh phase difference corresponding to the transceiver delay between the third signal and the seventh echo signal, the eighth phase difference corresponding to the transceiver delay between the third signal and the eighth echo signal, and the ninth phase difference corresponding to the transceiver delay between the third signal and the ninth echo signal. Furthermore, the control unit 10 calculates the first delay and the first frequency sweep slope change of the signal transmitted through the first cable, and the second delay and the second frequency sweep slope change of the signal transmitted through the second cable based on the first phase difference to the ninth phase difference. The specific calculation method is the same as above. Figure 2 The relevant descriptions in the illustrated embodiment are similar and will not be repeated here.

[0164] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application is described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A distributed radar, It is characterized in that The distributed radar comprises: a control unit, a receiving antenna and N transmitting antennas, where N is an integer greater than or equal to 3; The N transmitting antennas include a first transmitting antenna, a second transmitting antenna and a third transmitting antenna, and a distance between the first transmitting antenna and the control unit is smaller than a distance between other transmitting antennas and the control unit; The distance between the first transmitting antenna and the second transmitting antenna is a first distance, the distance between the first transmitting antenna and the third transmitting antenna is a second distance, and the first distance is smaller than the second distance; The first transmitting antenna is integrated with the control unit, the second transmitting antenna is connected to the control unit via a first cable, and the third transmitting antenna is connected to the control unit via a second cable, wherein a ratio of the first distance to the second distance is a first ratio, a ratio of a length of the first cable to a length of the second cable is a second ratio, and the second ratio is greater than the first ratio.

2. The distributed radar according to claim 1, It is characterized in that The second ratio is greater than a product of the first ratio and 1.5, and the second ratio is less than a product of a reciprocal of the first ratio and 10.

3. The distributed radar according to claim 1, It is characterized in that The length of the first cable is greater than the length of the second cable.

4. The distributed radar according to any one of claims 1 to 3, It is characterized in that The N transmitting antennas further include a fourth transmitting antenna, the distance between the first transmitting antenna and the fourth transmitting antenna is a third distance, and the second distance is smaller than the third distance; The fourth transmitting antenna is connected to the control unit via a third cable, a ratio of the first distance to the third distance is a third ratio, a ratio of the length of the first cable to the length of the third cable is a fourth ratio, and the fourth ratio is greater than the third ratio.

5. The distributed radar according to any one of claims 1 to 4, It is characterized in that The receiving antenna is integrated with the control unit.

6. The distributed radar according to any one of claims 1 to 5, It is characterized in that The first cable and the second cable are terahertz active cables TAC.

7. The distributed radar according to any one of claims 1 to 6, It is characterized in that The control unit includes a signal source, a signal separator and a processor; The signal source is used to: sending a first signal having a first frequency, a second signal having a second frequency, a third signal having the first frequency, a fourth signal having the second frequency, a fifth signal having the first frequency, and a sixth signal having the second frequency to the signal separator and the processor; The signal separator is used for: Send the first signal and the second signal to the first transmitting antenna, send the third signal and the fourth signal to the second transmitting antenna, and send the fifth signal and the sixth signal to the third transmitting antenna; The processor is used to: Acquire an echo signal corresponding to each transmitted signal from the receiving antenna; Calculating a phase difference corresponding to a transmission / reception delay between each of the transmission signals and each of the corresponding echo signals; According to the obtained phase difference set, a first delay of the signal transmitted through the first cable and a second delay of the signal transmitted through the second cable are calculated.

8. The distributed radar according to any one of claims 1 to 6, It is characterized in that The control unit is used for: Control the first transmitting antenna to transmit a first signal having a first frequency and a second signal having a second frequency, control the second transmitting antenna to transmit a third signal having the first frequency and a fourth signal having the second frequency, and control the third transmitting antenna to transmit a fifth signal having the first frequency and a sixth signal having the second frequency; Receiving an echo signal corresponding to each of the transmitted signals through the receiving antenna; Calculating a phase difference corresponding to a transmission / reception delay between each of the transmission signals and each of the corresponding echo signals; According to the obtained phase difference set, a first delay of the signal transmitted through the first cable and a second delay of the signal transmitted through the second cable are calculated.

9. The distributed radar according to claim 8, It is characterized in that The first cable and the second cable are TACs, and the control unit is further configured to: controlling the first transmitting antenna to transmit a seventh signal having a third frequency, controlling the second transmitting antenna to transmit an eighth signal having the third frequency, and controlling the third transmitting antenna to transmit a ninth signal having the third frequency; receiving, through the receiving antenna, a seventh echo signal of the seventh signal, an eighth echo signal of the eighth signal, and a ninth echo signal of the ninth signal; Calculating a seventh phase difference corresponding to a transceiver delay between the seventh signal and the seventh echo signal, an eighth phase difference corresponding to a transceiver delay between the eighth signal and the eighth echo signal, and a ninth phase difference corresponding to a transceiver delay between the ninth signal and the ninth echo signal; The control unit is also used for: A first frequency sweep slope change amount of a signal transmitted through the first cable and a second frequency sweep slope change amount of a signal transmitted through the second cable are calculated according to the phase difference set, the seventh phase difference, the eighth phase difference and the ninth phase difference.

10. The distributed radar according to claim 8 or 9, It is characterized in that The control unit is also used for: generating a first detection signal and a second detection signal; Performing delay compensation on the first detection signal according to the first delay to obtain a first transmission time, and performing delay compensation on the second detection signal according to the second delay to obtain a second transmission time; The second transmitting antenna is controlled to transmit the first detection signal at the first transmitting time, and the third transmitting antenna is controlled to transmit the second detection signal at the second transmitting time.

11. The distributed radar according to claim 8 or 9, It is characterized in that The control unit is also used for: Control the second transmitting antenna to transmit a first detection signal, and control the third transmitting antenna to transmit a second detection signal; receiving, by the receiving antenna, a first detection echo signal of the first detection signal and a second detection echo signal of the second detection signal; The first detection echo signal is delay compensated according to the first delay, and the second detection echo signal is delay compensated according to the second delay.

12. The distributed radar according to claim 8 or 9, It is characterized in that The signals transmitted by the N transmitting antennas are sinusoidal wave signals or narrowband amplitude modulated signals.

13. A distributed radar, It is characterized in that The distributed radar comprises: a control unit, a transmitting antenna and N receiving antennas, where N is an integer greater than or equal to 3; The N receiving antennas include a first receiving antenna, a second receiving antenna and a third receiving antenna, and the distance between the first receiving antenna and the control unit is smaller than the distance between the other receiving antennas and the control unit; The distance between the first receiving antenna and the second receiving antenna is a first distance, the distance between the first receiving antenna and the third receiving antenna is a second distance, and the first distance is smaller than the second distance; The first receiving antenna is integrated with the control unit, the second receiving antenna is connected to the control unit via a first cable, the third receiving antenna is connected to the control unit via a second cable, the ratio of the first distance to the second distance is a first ratio, the ratio of the length of the first cable to the length of the second cable is a second ratio, and the second ratio is greater than the first ratio.

14. The distributed radar according to claim 13, It is characterized in that The second ratio is greater than a product of the first ratio and 1.5, and the second ratio is less than a product of a reciprocal of the first ratio and 10.

15. The distributed radar according to claim 13, It is characterized in that The length of the first cable is greater than the length of the second cable.

16. The distributed radar according to any one of claims 13 to 15, It is characterized in that The N receiving antennas further include a fourth receiving antenna, the distance between the first receiving antenna and the fourth receiving antenna is a third distance, and the second distance is smaller than the third distance; The fourth receiving antenna is connected to the control unit via a third cable, a ratio of the first distance to the third distance is a third ratio, a ratio of the length of the first cable to the length of the third cable is a fourth ratio, and the fourth ratio is greater than the third ratio.

17. The distributed radar according to any one of claims 13 to 16, It is characterized in that The transmitting antenna is integrated with the control unit.

18. The distributed radar according to any one of claims 13 to 17, It is characterized in that The first cable and the second cable are terahertz active cables TAC.

19. The distributed radar according to any one of claims 13 to 18, It is characterized in that The control unit includes a signal source, a signal selector and a processor; The signal source is used to: sending a first signal having a first frequency and a second signal having a second frequency to the transmit antenna and the processor; The signal selector is used to: Acquire an echo signal corresponding to each transmitted signal from the first receiving antenna, the second receiving antenna, and the third receiving antenna, and send each of the echo signals to the processor; The processor is used to: Calculating a phase difference corresponding to a transmission / reception delay between each of the transmission signals and each of the corresponding echo signals; A first delay of a signal transmitted through the first cable and a second delay of a signal transmitted through the second cable are calculated based on the obtained phase difference set.

20. The distributed radar according to any one of claims 13 to 18, It is characterized in that The control unit is used for: Controlling the transmitting antenna to transmit a first signal having a first frequency and a second signal having a second frequency; Receiving an echo signal corresponding to each transmitted signal through the first receiving antenna, the second receiving antenna and the third receiving antenna; Calculating a phase difference corresponding to a transmission / reception delay between each of the transmission signals and each of the corresponding echo signals; A first delay of a signal transmitted through the first cable and a second delay of a signal transmitted through the second cable are calculated based on the obtained phase difference set.

21. The distributed radar according to claim 20, It is characterized in that The first cable and the second cable are TACs, and the control unit is further configured to: Controlling the transmitting antenna to transmit a third signal having a third frequency; receiving a seventh echo signal of the third signal through the first receiving antenna, receiving an eighth echo signal of the third signal through the second receiving antenna, and receiving a ninth echo signal of the third signal through the third receiving antenna; Calculating a seventh phase difference corresponding to a transceiver delay between the third signal and the seventh echo signal, an eighth phase difference corresponding to a transceiver delay between the third signal and the eighth echo signal, and a ninth phase difference corresponding to a transceiver delay between the third signal and the ninth echo signal; The control unit is also used for: A first frequency sweep slope change amount of a signal transmitted through the first cable and a second frequency sweep slope change amount of a signal transmitted through the second cable are calculated according to the phase difference set, the seventh phase difference, the eighth phase difference and the ninth phase difference.

22. The distributed radar according to claim 20 or 21, It is characterized in that The control unit is also used for: Controlling the transmitting antenna to transmit a detection signal; receiving a first detection echo signal of the detection signal through the second receiving antenna, and receiving a second detection echo signal of the detection signal through the third receiving antenna; The first detection echo signal is delay compensated according to the first delay, and the second detection echo signal is delay compensated according to the second delay.

23. The distributed radar according to claim 20 or 21, It is characterized in that The signal transmitted by the transmitting antenna is a sinusoidal wave signal or a narrowband amplitude modulated signal.

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