Ghost elimination device and working method for automobile radar target simulator

Abstract

The present invention relates to the technical field of radar target simulators, and provides a ghost elimination device for a vehicle radar target simulator and a working method thereof, comprising an adjustment circuit arranged between an internal circuit of the vehicle radar target simulator and a transceiver antenna; the adjustment circuit is used to simulate the crosstalk or mismatched reflection signal of the transceiver antenna of the radar target simulator. The problem that the target simulation signal has "ghost" false target information due to insufficient isolation of the transceiver antenna of the radar target simulator or port mismatch, which affects the performance test of the vehicle radar, is solved.

Description

Technical Field

[0001] The invention relates to the technical field of radar target simulators, and in particular to a ghost elimination device for an automobile radar target simulator and a working method thereof. Background Art

[0002] The statements in this section merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] At present, the working principle of mainstream automotive radar is to transmit a linear frequency sweep signal, which is reflected by the target and returns to the radar. Due to the time delay caused by the target distance, the reflected signal will form a frequency difference with the transmitted signal. By measuring the difference frequency and its phase change, the target distance and speed parameters can be obtained. The most direct way to measure the performance of automotive radar is to verify it on the spot, and set up moving or stationary physical targets in the test field. Combined with the actual state such as the speed of the car, the performance of the automotive radar can be directly judged based on the target excitation and speed parameters measured in real time by the automotive radar. However, field measurement is costly and inconvenient, and is not suitable for batch measurement and inspection of automotive radar equipment and key circuits on the production line.

[0004] In order to quickly and conveniently measure and verify the performance of automotive radar, the common method is to use an automotive radar target simulator. Its basic principle is to receive the automotive radar transmission signal in real time, and the internal circuit generates the difference frequency reflection signal of the set distance and speed target through mixing, modulation or delay, and then transmits it back to the automotive radar in real time to verify whether the automotive radar can correctly measure the target distance and speed information.

[0005] like Figure 1 As shown, the receiving antenna R of the automotive radar target simulator receives the instantaneous frequency f T After the car radar detects the signal, it is processed internally and then uses the transmitting antenna T to transmit a signal with an instantaneous frequency of f to the car radar. R The signal, f T =f0+a·t,f R =f T +Δf, f0 is the starting frequency of the sweep signal, t is the sweep time; simulate the reflection effect of the target at a distance of L on the car radar detection signal, f R With f T The frequency difference is Δf=a·Δt=a·2·L / c, where c is the speed of light, that is, the propagation speed of the radio signal; a is the sweep speed of the car radar signal.

[0006] The signal transmitting and receiving antennas of the radar target simulator can be shared or separate. Due to technical and cost reasons, the transmitting and receiving antennas cannot be completely independent and matched. The difference frequency transmission signal will partially interfere with the receiving channel and be treated as a receiving signal and processed again by difference frequency and fed to the transmitting antenna, and so on. Figure 2 As shown in the figure, the target simulator often feeds back a series of difference frequency signals (f R , f′ R , f″ R etc.), resulting in the automotive radar measuring a series of false target information, namely ghost images. When the ghost images are serious, the correlation between the signals can even interfere with the measurement mechanism of the automotive radar.

[0007] like Figure 2 As shown in the figure, it shows the situation of the virtual shadow caused by the crosstalk between the signals when the transmitting and receiving antennas of the radar target simulator are separate; when the transmitting and receiving antennas share the same antenna TR, the crosstalk between the transmitting and receiving antennas is equivalent to the mismatch between the antenna and the internal circuit of the target simulator, as shown in Figure 3 As shown, antenna mismatch will reflect part of the transmission signal fed to the antenna by the transmission channel into the receiving channel; the common feature is that part of the transmission signal returned to the automotive radar is returned to the target simulator in real time, and is returned to the automotive radar with a secondary frequency deviation, and this process is repeatedly iterated, resulting in a series of false target "phantoms", affecting the automotive radar performance test. Summary of the invention

[0008] In order to address the deficiencies in the prior art, the present invention provides a ghost elimination device for an automotive radar target simulator and a working method thereof, which solves the problem that insufficient isolation between the radar target simulator's transceiver antennas causes "ghost" false target information to exist in the target simulation signal, thus affecting the automotive radar performance test.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A first aspect of the present invention provides a ghost elimination device for an automobile radar target simulator.

[0011] A ghost elimination device for a vehicle radar target simulator, comprising a regulating circuit arranged between an internal circuit of the vehicle radar target simulator and a transceiver antenna;

[0012] The regulating circuit is used to simulate the crosstalk or mismatched reflected signal of the radar target simulator transceiver antenna.

[0013] Furthermore, in the case where the transmitting and receiving antennas are separate, it also includes a signal splitting circuit and a signal combining circuit;

[0014] The signal input end of the signal shunt circuit is connected to the transmitting channel of the radar target simulator, and the signal output end of the signal shunt circuit is connected to the transmitting antenna of the target simulator and the signal input end of the regulating circuit;

[0015] The signal input end of the signal combining circuit is connected to the target simulator receiving antenna and the signal output end of the regulating circuit, and the signal output end of the signal combining circuit is connected to the receiving channel of the radar target simulator.

[0016] Furthermore, in the regulation mode, the regulation circuit is a two-port circuit in which an adjustable attenuator and a phase shifter are connected in series.

[0017] Furthermore, in the regulation mode, the signal branching circuit and the signal combining circuit respectively adopt a power divider and a combiner.

[0018] Furthermore, in the non-adjustment mode, the adjustment circuit is a pair of auxiliary antennas having the same performance as the target simulator receiving antenna and the target simulator transmitting antenna.

[0019] Furthermore, in the non-adjustment mode, one of the signal splitting circuit and the signal combining circuit may use a waveguide HT power splitter, and the other may use a waveguide ET power splitter.

[0020] Furthermore, in the case where the transmitting and receiving antennas are shared, a waveguide magic T is also included;

[0021] The transmitting channel and receiving channel of the radar target simulator are respectively connected to the H arm in-phase port and the E arm inverting port of the waveguide magic T;

[0022] The transceiver antenna is connected to a symmetrical side arm port of the waveguide magic T;

[0023] The regulating circuit is connected to another symmetrical side arm port of the magic T.

[0024] Furthermore, in the regulation mode, the regulation circuit is a single-port network composed of an adjustable attenuator and a sliding short circuit.

[0025] Furthermore, in the non-adjustment mode, the adjustment circuit is an auxiliary antenna having the same performance as the transceiver antenna.

[0026] A second aspect of the present invention provides a working method of a ghost elimination device for an automobile radar target simulator.

[0027] The working method of the ghost elimination device for the automotive radar target simulator as described in the first aspect comprises the following steps:

[0028] The difference frequency signal generated by the internal circuit of the radar target simulator is divided into two paths, one is sent to the transceiver antenna, and the other enters the adjustment circuit. The adjustment circuit simulates the crosstalk or mismatched reflection signal of the transceiver antenna of the radar target simulator, and combines it with the signal of the transceiver antenna in equal value and antiphase to reach the internal circuit of the radar target simulator.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The ghost elimination device for the automobile radar target simulator described in the present invention utilizes the radar target simulator itself to generate a target difference frequency signal, and through a combination of microwave electronic devices, automatically and in real time offsets the mismatch crosstalk signal of the transceiver antenna, thereby achieving ghost elimination of the radar target simulator, thereby solving the problem of manually eliminating the ghosting effect when using the radar target simulator to test the automobile radar.

[0031] 2. The ghost elimination device for the automotive radar target simulator of the present invention can be simply connected in series between the transmitting and receiving antenna and the internal circuit of the radar target simulator without changing the internal circuit structure of the radar target simulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute improper limitations on the present invention.

[0033] Figure 1 A connection diagram of an existing automotive radar target simulator, automotive radar, and a transceiver antenna;

[0034] Figure 2 This is a schematic diagram of a virtual shadow caused by signal crosstalk between antennas when the existing transmitting and receiving antennas are separated;

[0035] Figure 3 Schematic diagram of ghost images caused by antenna mismatch when existing transmitting and receiving antennas are shared;

[0036] Figure 4 It is a structural diagram of a ghost elimination device for a vehicle radar target simulator of the present invention;

[0037] Figure 5 This is a structural diagram of a ghost elimination device for an automobile radar target simulator according to Embodiment 2 of the present invention;

[0038] Figure 6 This is a structural diagram of a ghost elimination device for an automobile radar target simulator according to embodiment 3 of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0040] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0041] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0043] The embodiment of the present invention provides a ghost elimination device for an automobile radar target simulator, which is arranged between an internal circuit of the radar target simulator and a transceiver antenna, and automatically eliminates ghosts caused by crosstalk or mismatch reflection between the transceiver antennas. The radar target simulator is an automobile radar target simulator.

[0044] like Figure 4 As shown, it includes an adjustment circuit, a signal splitting circuit and a signal combining circuit arranged between the internal circuit of the automobile radar target simulator and the transceiver antenna; the adjustment circuit is used to simulate the crosstalk or mismatched reflection signal of the transceiver antenna of the radar target simulator.

[0045] According to the form of the target simulator's transceiver antenna and the sweep width characteristics of the measured vehicle radar signal, the signal splitting circuit, combining circuit and adjustment circuit have four selection and combination working modes, namely, the adjustment mode AN and the non-adjustment mode AW when the transceiver antennas are separate, and the adjustment mode BN and the non-adjustment mode BW when the transceiver antennas are shared. Figure 4 The dotted line in the figure represents the case where the transmitting and receiving antennas are separate, and the solid line represents the case where the transmitting and receiving antennas are shared.

[0046] Among them, the difference between the adjustment mode and the non-adjustment mode is: the cost of the adjustment mode is lower than that of the non-adjustment mode; the adjustment mode is simpler than the non-adjustment mode; the adjustment mode can theoretically only completely eliminate ghosting at one frequency point, and as the sweep width of the automotive radar increases, ghosting will gradually appear, and the ghosting intensity is positively correlated with the sweep width; the ghosting elimination capability of the non-adjustment mode is theoretically independent of the sweep width; the adjustment mode and the non-adjustment mode can be selected according to actual test requirements.

[0047] Example 1

[0048] Embodiment 1 of the present invention provides a ghost elimination device for an automobile radar target simulator, which belongs to adjustment mode AN in the case where the transmitting and receiving antennas are separated.

[0049] The ghost elimination device for the automobile radar target simulator provided in this embodiment includes a regulating circuit, a signal splitting circuit and a signal combining circuit arranged between the internal circuit of the automobile radar target simulator and the transceiver antenna.

[0050] A signal splitting circuit may use a power divider; a signal combining circuit may use a combiner, typically a reverse-connected power divider.

[0051] The regulating circuit is a two-port circuit composed of an adjustable attenuator and a phase shifter connected in series.

[0052] like Figure 4 As shown, the transmitting channel port 2 of the radar target simulator is connected to the signal input end of the signal branching circuit, and the signal output end of the signal branching circuit is connected to the simulator transmitting antenna T and the signal input end 5 of the adjustment circuit; the signal output end 4 of the adjustment circuit is connected to the signal input end port 1 of the signal combining circuit, the other input end of the signal combining circuit is connected to the simulator receiving antenna R, and the signal output end of the signal combining circuit is connected to the receiving channel 1 of the radar target simulator.

[0053] The adjustment circuit is used to simulate the crosstalk signal of the radar target simulator's transceiver antenna, and realizes equal-amplitude anti-phase synthesis and cancellation with the crosstalk signal through the signal splitting circuit and the signal combining circuit. For automotive radar signals with a small sweep width, the adjustment circuit can be composed of an adjustable attenuator and a phase shifter, which can adjust the amplitude and phase of the crosstalk simulation signal. The cancellation effect can be verified by measuring the transmission coefficient from port 2 to port 1 with a vector network analyzer. Adjusting the phase shifter will cause the transmission coefficient to change along a circular trajectory in the complex plane. The center of the circle corresponds to the influence of the crosstalk signal, and the transmission coefficient is the result of eliminating the influence; adjusting the attenuator will change the radius of the circular trajectory. The combined adjustment can change the transmission coefficient to the origin, then the transmission coefficient amplitude is zero, that is, the influence of the crosstalk signal is offset, and ghosting is eliminated.

[0054] Example 2

[0055] The functional principle of the embodiment 2 of the present invention is similar to that of the embodiment 1, and belongs to the adjustment mode BN in the case of a shared transmitting and receiving antenna. The receiving antenna R and the transmitting antenna T are combined into the transmitting and receiving antenna TR, forming a unique shared input and output port 3.

[0056] like Figure 5As shown in the figure, to adapt to the single-port characteristics of the transmitting and receiving antennas, the signal splitting circuit and the signal combining circuit are combined into a waveguide magic T device; the transmitting channel port 2 and the receiving channel port 1 of the radar target simulator are respectively connected to the H-arm in-phase port and the E-arm anti-phase port of the magic T; the transmitting and receiving antenna port 3 is connected to a symmetrical side arm port of the magic T; the adjustment circuit signal output port 4 and the signal input port 5 are combined, degenerating into a single-port network composed of an adjustable attenuator and a sliding short circuit, connecting another symmetrical side arm port of the magic T.

[0057] The difference frequency signal generated by the radar target simulator is sent to the magic T through the transmitting channel. Utilizing the properties of the magic T, it is equally divided and reaches the transmitting and receiving antennas and the adjustment circuit with equal amplitude and phase, and the respective reflected signals are transmitted to the receiving channel in equal proportion and inverse phase. If the port reflection characteristics of the adjustment circuit are the same as those of the transmitting and receiving antennas, the two signals will cancel each other out, thereby achieving the purpose of eliminating ghosting.

[0058] For automotive radar signals with a small sweep width, the adjustment circuit of this embodiment uses a combination of an adjustable attenuator and a sliding short circuit to conveniently adjust the characteristics of the simulated transceiver antenna mismatch reflection signal. The same method as in Example 1 can be used to measure the transmission coefficient from port 2 to port 1 using a vector network analyzer to indicate the adjustment of the adjustment circuit and verify the adjustment effect. Among them, the sliding short circuit replaces the phase shifter.

[0059] Example 3

[0060] The basic principle of the ghost elimination device for the automotive radar target simulator provided in this embodiment is as follows: Figure 6 As shown, it belongs to the non-adjustment mode BW when the transmitting and receiving antennas are shared.

[0061] For the case of the transmitting and receiving antennas in Example 2, when the sweep width of the automobile radar signal is large, it is not easy to adjust and achieve ideal cancellation of the entire sweep range. For this reason, a symmetrical cancellation method can be used, that is, the adjustment circuit is replaced with an auxiliary antenna with the same performance as the transmitting and receiving antenna, which can also achieve the cancellation of mismatched signals, such as Figure 6 shown.

[0062] In order to avoid external interference, the auxiliary antenna should maintain the same external space environment as the transceiver antenna, and the signal should have the same transmission electrical length from the simulator transmitting channel port through the antenna to the receiving channel port.

[0063] As an implementation method, the auxiliary antenna is enclosed in the shielding absorption space. Under a good symmetrical circuit structure, no additional electrical adjustment is required.

[0064] Example 4

[0065] The ghost elimination device for the automobile radar target simulator provided in this embodiment belongs to the non-adjustment mode AW in the case where the transmitting and receiving antennas are separated.

[0066] In the case of separate transmitting and receiving antennas in embodiment 1, when the sweep width of the automobile radar signal is large, it is also not easy to adjust to achieve ideal cancellation of the entire sweep range. For this reason, a symmetrical cancellation method similar to embodiment 3 can be used, and the adjustment circuit can be replaced with a pair of auxiliary antennas with the same performance as the receiving and transmitting antennas, and the signal splitting circuit and the signal combining circuit can use a waveguide HT power splitter in one and a waveguide ET power splitter in the other, and the crosstalk signal can be canceled through reverse synthesis of the signal splitting circuit and the signal combining circuit.

[0067] The auxiliary transmitting and receiving discrete antenna pair and the radar simulator transmitting and receiving discrete antenna pair are symmetrically connected to two symmetrical ports of ET and HT respectively.

[0068] As a special case, the signal splitting circuit and signal combining circuit connected to the receiving channel and the transmitting channel use an ET power divider and an HT power divider respectively, so as to realize the anti-phase synthesis of the antenna crosstalk signal and its analog signal. Similar to Example 3, the auxiliary antenna maintains the same external space environment as the receiving and transmitting antennas, and the crosstalk signal has the same internal transmission circuit electrical length, so no additional electrical adjustment is required.

[0069] Example 5

[0070] This embodiment provides a working method of the ghost elimination device for the automotive radar target simulator described in Embodiment 1, Embodiment 2, Embodiment 3 or Embodiment 4, comprising the following steps:

[0071] The difference frequency signal generated by the internal circuit of the radar target simulator is divided into two paths, one is sent to the transceiver antenna, and the other enters the adjustment circuit. The adjustment circuit simulates the crosstalk or mismatch reflection signal of the transceiver antenna of the radar target simulator, and is combined with the signal of the transceiver antenna in equal value and anti-phase to reach the internal circuit of the radar target simulator. Specifically, in the case of small span, the adjustment circuit directly realizes equal value anti-phase, and then directly synthesizes with the same phase synthesizer; in the case of large span, the auxiliary antenna is used to generate equal value (in-phase) signals, and the magic T or ET and HT combination is used to realize anti-phase synthesis.

[0072] A vector network analyzer is used to measure the transmission coefficient of the ghost elimination device for the automotive radar target simulator from the radar target simulator transmitting channel connection port to the receiving channel port. Adjusting the phase shifter or the sliding short circuit will make the transmission coefficient change along a circular trajectory in the complex plane, and adjusting the attenuator will change the radius of the circular trajectory. The combined adjustment makes the transmission coefficient as close as possible to the origin of the complex plane, that is, the transmission coefficient modulus tends to zero.

[0073] For the AN and BN modes, the adjustment circuit needs to be pre-adjusted in order to effectively achieve the cancellation of the crosstalk or mismatched reflected signals of the radar target simulator's transceiver antenna in the receiving channel. The specific method is to use the connection method of the reference circuit and the automotive radar target simulator, replace the target simulator signal transmission channel and receiving channel with the transceiver port of the vector network analyzer, and measure the transmission coefficient: fix the attenuator, adjust the phase shifter (or sliding short circuit), then the trajectory of the transmission coefficient in the complex plane is a circle; adjust the attenuator, then the radius of the circle can be changed so that the circumference passes through the origin of the complex plane; then adjust the phase shifter so that the transmission coefficient approaches the origin along the circumference; repeatedly adjust the attenuator and phase shifter so that the transmission coefficient value reaches the origin, that is, the modulus value is zero, and the function of canceling the crosstalk or mismatched signal is achieved.

[0074] For AW and BW modes, no additional electrical adjustment is required, but the equivalence of the auxiliary antenna and the performance of the shielded absorption cavity will affect the degree of crosstalk or mismatch signal cancellation. The effect can also be verified by measuring the transmission coefficient using a vector network analyzer.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A ghost elimination device for a vehicle radar target simulator, characterized in that: It includes a regulating circuit arranged between an internal circuit of a vehicle radar target simulator and a transceiver antenna; The regulating circuit is used to simulate the crosstalk or mismatched reflected signal of the radar target simulator transceiver antenna; In the case where the transmitting and receiving antennas are separate, it also includes a signal splitting circuit and a signal combining circuit; The signal input end of the signal shunt circuit is connected to the transmitting channel of the radar target simulator, and the signal output end of the signal shunt circuit is connected to the transmitting antenna of the target simulator and the signal input end of the regulating circuit; The signal input end of the signal combining circuit is connected to the target simulator receiving antenna and the signal output end of the regulating circuit, and the signal output end of the signal combining circuit is connected to the receiving channel of the radar target simulator; In the case of shared transmit and receive antennas, it also includes the Waveguide Magic T; The transmitting channel and receiving channel of the radar target simulator are respectively connected to the H arm in-phase port and the E arm inverting port of the waveguide magic T; The transceiver antenna is connected to a symmetrical side arm port of the waveguide magic T; The regulating circuit is connected to another symmetrical side arm port of the magic T.

2. The ghost elimination device for a vehicle radar target simulator as claimed in claim 1, characterized in that: In the regulation mode, the regulation circuit is a two-port circuit composed of an adjustable attenuator and a phase shifter connected in series.

3. The ghost elimination device for a vehicle radar target simulator as claimed in claim 1, characterized in that: In the regulation mode, the signal splitting circuit and the signal combining circuit respectively use a power divider and a combiner.

4. The ghost elimination device for a vehicle radar target simulator as claimed in claim 1, characterized in that: In the non-adjustment mode, the adjustment circuit is a pair of auxiliary antennas having the same performance as the target simulator receiving antenna and the target simulator transmitting antenna.

5. The ghost elimination device for a vehicle radar target simulator as claimed in claim 1, characterized in that: In the non-adjustment mode, one of the signal splitting circuit and the signal combining circuit may use a waveguide HT power splitter, and the other may use a waveguide ET power splitter.

6. The ghost elimination device for a vehicle radar target simulator as claimed in claim 1, characterized in that: In the regulation mode, the regulation circuit is a single-port network composed of an adjustable attenuator and a sliding short circuit.

7. The ghost elimination device for a vehicle radar target simulator as claimed in claim 1, characterized in that: In the non-adjustment mode, the adjustment circuit is an auxiliary antenna with the same performance as the transceiver antenna.

8. The working method of the ghost elimination device for the automotive radar target simulator according to any one of claims 1 to 7, characterized in that: The steps include: The difference frequency signal generated by the internal circuit of the radar target simulator is divided into two paths, one is sent to the transceiver antenna, and the other enters the adjustment circuit. The adjustment circuit simulates the crosstalk or mismatched reflection signal of the transceiver antenna of the radar target simulator, and combines it with the signal of the transceiver antenna in equal value and antiphase to reach the internal circuit of the radar target simulator.

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