CN114966701A - Radar detection system and interference cancellation method - Google Patents
Radar detection system and interference cancellation method Download PDFInfo
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- CN114966701A CN114966701A CN202210646793.9A CN202210646793A CN114966701A CN 114966701 A CN114966701 A CN 114966701A CN 202210646793 A CN202210646793 A CN 202210646793A CN 114966701 A CN114966701 A CN 114966701A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/93—Radar or analogous systems specially adapted for specific applications for anti-collision purposes
- G01S13/931—Radar or analogous systems specially adapted for specific applications for anti-collision purposes of land vehicles
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/023—Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques
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Abstract
The embodiment of the application relates to the field of radar detection circuit design, in particular to a radar detection system and an interference elimination method, which comprise the following steps: the signal receiver includes: the mixer, the signal transmitter includes: a signal processing module; the detection module is connected with the input end of the baseband circuit and used for acquiring a first signal, and the first signal is a signal received by the input end of the baseband circuit; the signal processing module is connected with the detection module, is used for receiving the carrier signal, and is configured to acquire the adjusting frequency of the sub-signal corresponding to the interfering object in the first signal relative to the carrier signal and adjust the frequency of the carrier signal based on the adjusting frequency to generate an adjusting signal; the signal transmitter sends out a detection signal based on the adjustment signal; a mixer for receiving the reflected signal and the carrier signal and coupled to the input of the baseband circuit, configured to mix the reflected signal and the carrier signal to generate a second signal and input the second signal to the baseband circuit.
Description
Technical Field
The embodiment of the application relates to the field of vehicle-mounted radar detection circuit design, in particular to a radar detection system and an interference elimination method.
Background
Radar is an electronic device that detects a target using electromagnetic waves, and obtains information on a distance, a change rate of distance (radial velocity), an azimuth, an altitude, and the like from the target to an electromagnetic wave transmission point by radiating the electromagnetic waves and receiving echoes thereof, that is, finds the target by radio and measures their spatial position, and is also called "radio positioning".
Correspondingly, for the millimeter wave radar, the radar emits the millimeter waves, the millimeter waves meet the physics to be reflected, and the radar calculates the distance between the physics and the radar by calculating the time difference between the emission and the reception of the millimeter waves.
The millimeter wave radar is generally arranged behind a front baffle of an automobile, the front baffle causes extremely strong reflection energy due to the fact that the front baffle is very close to the radar (generally within 2 centimeters), and the reflected energy of a target object (such as an object at a distance of 0.5 to 300 meters) which is really desired to be detected is far less than the energy reflected by the baffle, so that the reflection energy of the baffle can completely submerge the reflection energy of the target object, and the signal-to-noise ratio or linearity of the reflection energy of the target object received by the radar is greatly reduced.
How to remove the reflected energy of the close-distance obstacle to improve the signal-to-noise ratio and the linearity of the energy reflected by the target object is a technical problem to be solved at present.
Disclosure of Invention
The embodiment of the application provides a radar detection system and an interference elimination method, and the frequency of a detection signal is adjusted, and after carrier stripping is carried out on a reflection signal, the reflection energy of a close-distance obstacle is removed, so that the detection quality of a vehicle-mounted radar is greatly improved with smaller power consumption.
In order to solve the above technical problem, an embodiment of the present application provides a radar detection system, which sends out a detection signal based on a signal transmitter, and receives a reflected signal of an object based on a signal receiver, including: the signal receiver includes: the mixer, the signal transmitter includes: a signal processing module; the detection module is connected with the input end of the baseband circuit and used for acquiring a first signal, and the first signal is a signal received by the input end of the baseband circuit; the signal processing module is connected with the detection module, is used for receiving the carrier signal, and is configured to acquire the adjusting frequency of the sub-signal corresponding to the interfering object in the first signal relative to the carrier signal and adjust the frequency of the carrier signal based on the adjusting frequency to generate an adjusting signal; the signal transmitter sends out a detection signal based on the adjustment signal; a mixer for receiving the reflected signal and the carrier signal and connected to the input of the baseband circuit, configured to mix the reflected signal and the carrier signal to generate a second signal and input the second signal to the baseband circuit.
According to the embodiment of the application, the frequency of the carrier signal is adjusted to obtain the adjusting signal, the signal transmitter is used as the carrier to send out the detection signal based on the adjusting signal, after the carrier stripping is carried out on the reflection signal, the reflection energy of an interference object is weakened in the obtained second signal, and the detection quality of the vehicle-mounted radar is greatly improved with smaller power consumption; in addition, many general radar designs already have frequency modulation equipment of carrier signal, and this application realizes interfering object reflection energy's elimination through changing the regulation method and the connected mode of frequency modulation equipment on general radar detection circuit's basis, has further reduced the consumption of eliminating interfering object reflection energy.
In addition, a signal processing module includes: a first processing unit configured to receive and adjust a frequency of a carrier signal; the second processing unit is connected with the detection module and is configured to obtain a preset value, and the preset value is a difference value between the maximum amplitude and the minimum amplitude in the first signal; the third processing unit is connected with the first processing unit and the second processing unit and is configured to acquire a change curve between a preset value and the frequency of the carrier signal and acquire an adjusting frequency based on the change curve, wherein the adjusting frequency is a frequency corresponding to the minimum value of the preset value in the change curve; and the fourth processing unit is connected with the third processing unit and receives the carrier signal, and is configured to adjust the carrier signal based on the adjusting frequency and generate an adjusting signal.
In addition, the signal processing module further includes: a fifth processing unit configured to receive and adjust a phase of a carrier signal; the sixth processing unit is connected with the detection module and is configured to acquire the maximum amplitude of the first signal; the seventh processing unit is connected with the fifth processing unit and the sixth processing unit and is configured to acquire a variation curve between the maximum amplitude of the first signal and the phase of the carrier signal and acquire an adjusting phase based on the variation curve, wherein the adjusting phase is a phase corresponding to the minimum value of the maximum amplitude in the variation curve; the fourth processing unit is further coupled to the seventh processing unit and is further configured to adjust the carrier signal based on the adjusted phase. On the basis of adjusting the frequency of the carrier signal by the signal processing module, phase adjustment of the carrier signal is added, so that sub-signals corresponding to interference objects in the reflected signal are completely removed, and the detection quality of the vehicle-mounted radar is further improved.
In addition, the radar detection system further includes: the interference cancellation current source is arranged on a transmission circuit of the frequency mixer connected with the baseband circuit; the signal processing module is further configured to: acquiring an adjusting phase of a sub-signal corresponding to an interference object in a first signal relative to a carrier signal; the interference cancellation current source is further connected with the signal processing module, the input end of the interference cancellation current source is connected with the transmission circuit, and the current value is set based on the amplitude of the carrier signal corresponding to the adjusting phase.
In addition, the radar detection system further includes: and the filter is connected to a signal path between the detection module and the signal processing module, the input end of the filter is connected with the detection module, and the output end of the filter is connected with the signal processing module.
The embodiment of the present application further provides an interference cancellation method, which is applied to the radar detection system provided in the above embodiment, and the method includes: acquiring a first signal received by a baseband circuit, and acquiring the adjusting frequency of a sub-signal corresponding to an interference object in the first signal relative to a carrier signal; acquiring a carrier signal, adjusting the frequency of the carrier signal based on the adjusting frequency, and generating an adjusting signal; sending a detection signal by taking the adjustment signal as a carrier, and receiving a reflection signal generated by the target object reflecting the detection signal; the carrier in the reflected signal is stripped based on the carrier signal, a second signal is generated, and the second signal is input to the baseband circuit.
In addition, acquiring the adjusting frequency or the adjusting phase of the sub-signal corresponding to the interfering object in the first signal relative to the carrier signal includes: acquiring a preset value, wherein the preset value is the difference value between the maximum amplitude and the minimum amplitude in the first signal; and adjusting the frequency of the carrier signal, acquiring a change curve between the preset value and the frequency of the carrier signal, and acquiring an adjusting frequency based on the change curve, wherein the adjusting frequency is the frequency corresponding to the minimum value of the preset value in the change curve.
In addition, acquiring an adjustment frequency or an adjustment phase of a sub-signal corresponding to an interfering object in the first signal with respect to the carrier signal, further includes: acquiring an adjusting phase of a sub-signal corresponding to an interference object in a first signal relative to a carrier signal; in the process of generating the adjustment signal, the method further comprises: the phase of the carrier signal is adjusted based on the adjusted phase.
In addition, acquiring the adjusting frequency or the adjusting phase of the sub-signal corresponding to the interfering object in the first signal relative to the carrier signal, further includes: acquiring an adjusting phase of a sub-signal corresponding to an interference object in a first signal relative to a carrier signal; in the process of inputting the second signal to the baseband circuit, the method further comprises: and acquiring the interference amplitude of the carrier signal corresponding to the adjusted phase, and removing the transmission current of the interference amplitude.
In addition, after the second signal is input to the baseband circuit, the method further includes: the measured distance of the target object is compensated based on the adjusted frequency, the measured distance being obtained by the baseband circuit based on the second signal.
Drawings
One or more embodiments are illustrated by corresponding figures in the drawings, which are not to be construed as limiting the embodiments, unless expressly stated otherwise, the drawings are not to scale; in order to more clearly illustrate the embodiments of the present disclosure or technical solutions in the conventional art, the drawings required to be used in the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without inventive efforts.
Fig. 1 is a schematic structural diagram of a radar detection system according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a signal processing module according to an embodiment of the present application;
fig. 3 is a schematic diagram illustrating a variation curve between a preset value and a frequency of a carrier signal according to an embodiment of the present disclosure;
fig. 4 is a schematic diagram illustrating a comparison of an influence of an interfering object signal in a first signal on a target object signal according to an embodiment of the present application;
fig. 5 is a schematic structural diagram of a signal processing module according to an embodiment of the present application;
fig. 6 is a schematic diagram illustrating a variation curve of a maximum amplitude of a first signal and a phase of a carrier signal according to an embodiment of the disclosure;
fig. 7 is a schematic structural diagram of a radar detection system with an interference current source according to an embodiment of the present disclosure;
FIG. 8 is a schematic structural diagram of a radar detection system with a filter according to an embodiment of the present disclosure;
fig. 9 is a flowchart illustrating an interference cancellation method according to another embodiment of the present application.
Detailed Description
As known in the background art, a millimeter wave radar is generally disposed behind a front baffle of an automobile, the front baffle is very close to the radar (usually within 2 cm), and therefore extremely strong reflected energy is generated, and a target object (for example, an object at a distance of 0.5 m to 300 m) which is really desired to be detected has far less reflected energy than the energy reflected by the baffle, so that the reflected energy of the baffle can completely submerge the reflected energy of the target object, and the signal-to-noise ratio or linearity of the reflected energy of the target object received by the radar is greatly reduced.
At present, in the prior art, a cancellation circuit is introduced to a transformer of a receiving circuit of a radar, and reflected energy of a short-distance obstacle is cancelled by the cancellation circuit, but the transformer of the receiving circuit is used as a front-end circuit of the radar, at this time, signals are not amplified, and noise introduced by the cancellation circuit can also significantly reduce the signal-to-noise ratio and the linearity of the reflected energy of a target object; in addition, in the prior art, a cancellation circuit is introduced into a baseband circuit of the radar, but at this time, reflected energy of a short-distance obstacle is amplified, and the cancellation circuit also needs to provide a signal with large energy to cancel the reflected energy of the short-distance obstacle, so that the cancellation circuit needs to be designed into a circuit with large power consumption, and the baseband circuit is a signal path, and signal cancellation is performed on the baseband circuit, which also introduces large noise.
An embodiment of the application provides a radar detection system, through the frequency of adjustment detection signal, carries out the carrier wave to the reflection signal and peels off the back to get rid of the reflection energy of closely barrier, with less consumption greatly improved vehicle radar's detection quality.
Embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, it will be appreciated by those of ordinary skill in the art that in the various embodiments of the present application, numerous technical details are set forth in order to provide a better understanding of the present application. However, the technical solution claimed in the present application can be implemented without these technical details and various changes and modifications based on the following embodiments.
Fig. 1 is a schematic structural diagram of a radar detection system provided in this embodiment, fig. 2 is a schematic structural diagram of a signal processing module provided in this embodiment, fig. 3 is a schematic structural diagram of a change curve between a preset value and a frequency of a carrier signal provided in this embodiment, fig. 4 is a schematic structural diagram of a comparison between an interfering object signal in a first signal provided in this embodiment and a target object signal, fig. 5 is another schematic structural diagram of the signal processing module provided in this embodiment, fig. 6 is a schematic structural diagram of a change curve between a maximum amplitude of the first signal and a phase of the carrier signal provided in this embodiment, fig. 7 is a schematic structural diagram of a radar detection system provided in this embodiment and having an interfering current source, fig. 8 is a schematic structural diagram of a radar detection system provided in this embodiment and having a filter, and the following describes the radar detection system provided in this embodiment in detail with reference to the drawings, the method comprises the following specific steps:
referring to fig. 1, a radar detection system, based on a signal transmitter 20 emitting a probe signal and based on a signal receiver 10 receiving a reflected signal of an object, includes:
the signal receiver 10 comprises a mixer 103 and the signal transmitter 20 comprises a signal processing module 102.
The detection module 101 is connected to an input terminal of the baseband circuit 104 and configured to obtain a first signal IF0, where the first signal IF0 is a signal received by the input terminal of the baseband circuit 104.
It should be noted that, this embodiment does not limit the position of the detection module 101, and in a specific application process, the detection module 101 may be disposed in the signal receiver 10, may be disposed in the signal transmitter 20, or may be disposed independently of the signal receiver 10 and the signal transmitter 20.
The baseband circuit 104 is configured to obtain information between the target object and the radar electromagnetic wave emitting point according to the received signal. Specifically, the baseband circuit 104 is configured to perform signal analysis processing according to the received signal, so as to obtain information such as a distance, a distance change rate, an azimuth, and an altitude between the positioning object and a radar electromagnetic wave emission point. In the following description, the radar detection system provided in the present embodiment is described in detail by taking distance information as an example, which is not a limitation to the present embodiment, and in other embodiments, the radar detection system is also applicable to adjustment methods of information such as a distance change rate, an azimuth, and an altitude.
The first signal IF0 is generated by the mixer 103 mixing a reflected signal RF, i.e., a radar reflection wave received by a radar transmission point, with a carrier signal LO0, and the carrier signal LO0 is used to strip the carrier signal in the reflected signal RF, thereby obtaining a first signal IF0, and the first signal IF0 carries distance information of a target object and a short-distance obstacle object (interfering object).
It should be noted that, this embodiment does not limit the position of the detection module 101, and in a specific application process, the detection module 101 may be disposed in the signal receiver 10, may be disposed in the signal transmitter 20, or may be disposed independently of the signal receiver 10 and the signal transmitter 20.
A signal processing module 102, connected to the detection module 101 and configured to receive the carrier signal LO0, configured to obtainAdjustment frequency f of a sub-signal corresponding to an interfering object in first signal IF0 with respect to carrier signal LO0 M And based on the regulation frequency f M The frequency of the carrier signal LO0 is adjusted to generate the adjustment signal LOt.
The signal transmitter 20 emits a detection signal based on the adjustment signal LOt.
A mixer 103 for receiving the reflected signal RF and the carrier signal LO0 and coupled to an input of the baseband circuitry 104 and configured to mix the reflected signal RF and the carrier signal LO0 to generate a second signal IFt and input the second signal IFt to the baseband circuitry 104; it should be noted that, at this time, the second signal IFt input to the baseband circuit 104 continues to be detected by the detection module 101 as the first signal IF 0.
For the mixer 103 mentioned in the present embodiment, assuming that two waves for mixing cosA and cosB are used, the operation principle of the mixer 103 is: cosA × cosB is 1/2[ cos (a + B) + cos (a-B) ], and since the frequency of cos (a + B) is high, the waveform obtained by mixing cosA and cosB at this time is 1/2cos (a-B) after high-frequency filtering is performed inside the mixer 103.
The frequency of the carrier signal LO0 is adjusted to obtain an adjusting signal LOt, the signal transmitter 20 sends out a detection signal based on the adjusting signal LOt as a carrier, and after carrier stripping is performed on the reflected signal RF, the reflected energy of an interfering object is weakened in the obtained second signal IFt, so that the detection quality of the vehicle-mounted radar is greatly improved with smaller power consumption; in addition, many general radar designs have frequency modulation equipment of a carrier signal LO0, and the method realizes elimination of the reflected energy of the interference object and further reduces power consumption for eliminating the reflected energy of the interference object on the basis of a general radar detection circuit by changing the adjusting method and the connection mode of the frequency modulation equipment.
In one example, referring to fig. 2, the signal processing module 102 includes: a first processing unit 112 configured to receive and adjust the frequency of a carrier signal LO 0; the second processing unit 122 is connected to the detection module 101, and is configured to obtain a preset value, where the preset value is a difference between a maximum amplitude and a minimum amplitude in the first signal IF 0; a third processing unit 132 connected to the first processing unit 112 and the second processing unit 122, is connected toConfigured to acquire a variation curve between a preset value and a frequency of a carrier signal, and acquire an adjustment frequency f based on the variation curve M Adjusting the frequency f M The frequency is the frequency corresponding to the minimum value of the preset values in the change curve; a fourth processing unit 142, connected to the third processing unit 132 and receiving the carrier signal LO0, configured to adjust the frequency f M The carrier signal LO0 is adjusted to generate the adjustment signal LOt.
Specifically, the first processing unit 112, the second processing unit 122 and the third processing unit 132 are configured to continuously adjust the frequency of the carrier signal LO0 to obtain the adjustment frequency f during the test phase M (ii) a When the fourth processing unit 142 is used for the actual application of the radar detection system, the adjustment frequency f is obtained M Generation of a detection signal is performed.
The working principle of the radar detection system is as follows:
LO0＝A 0 COS(ω 0 t+kt 2 +θ 0 )(1)
RF＝A g COS[ω 0 (t-△t)+k(t-△t) 2 +θ g ]+∑A i COS[ω 0 (t-△t i )+k(t-△t i ) 2 +θ i ](2)
for formula (2), wherein A g COS[ω 0 (t-△t)+k(t-△t) 2 +θ g ]In order to disturb the reflected signal of the object, Σ
A i COS[ω 0 (t-△t i )+k(t-△t i ) 2 +θ i ]Is a reflected signal of the target object; based on the operation principle of the mixer 103, IF0 ═ RF ═ LO0 ═ BCOS [ (-2k Δ t) t + θ [ (-2k Δ t) at this time g -ω 0 △t+k△t 2 -θ 0 ]+∑B i COS[(-2k△t i )t+θ g -ω 0 △t i +k△t i 2 -θ 0 ](3)
As can be seen from the formula (3), the identification signal of the interfering object obtained by removing the carrier from the reflected signal of the interfering object is BCOS [ (-2k Δ t) t + θ g -ω 0 △t+k△t 2 -θ 0 ]I.e. the frequency of the identification signal of the interfering object is-2k Δ t, the phase of the identification signal of the interfering object being θ g -ω 0 △t+k△t 2 -θ 0 。
The frequency of the carrier signal LO0 is continuously adjusted by the first processing unit 112, the second processing unit 122, and the third processing unit 132 to generate the adjustment signal LOt, where LOt is equal to 0 COS(ω 0 t+kt 2 +θ 0 -△ωt)(4)
Based on the operation principle of the mixer 103, IFt ═ RF × LOt ═ BCOS [ (. DELTA.. omega. -2 k.DELTA.t) t + θ g -ω 0 △t+k△t 2 -θ 0 ]+∑B i COS[(△ω-2k△t i )t+θ g -ω 0 △t i +k△t i 2 -θ 0 ](5)
For equation (5), the function curve diagram is the variation curve between the preset value A2 and the frequency f of the carrier signal, the variation curve diagram refers to FIG. 3, and the adjustment frequency f is obtained according to FIG. 3 M As can be seen from equation (5) in conjunction with FIG. 3, the frequency f is now adjusted M ＝2k△t。
When the fourth processing unit 142 adjusts the frequency f M After adjusting the generated adjustment signal LOt, IFt is BCOS (θ) g -ω 0 △t+k△t 2 -θ 0 )+∑B i COS[(2k△t-2k△t i )t+θ g -ω 0 △t i +k△t i 2 -θ 0 ]Wherein, BCOS (theta) g -ω 0 △t+k△t 2 -θ 0 ) As a constant term, only the amplitude of the second signal IFt is affected, and the frequency of the second signal IFt is not affected, thereby eliminating the signal reflected by the interfering object in the reflected signal RF, and BCOS (θ) g -ω 0 △t+k△t 2 -θ 0 ) As a constant current, it can be removed as a bias current in a subsequent operation.
Referring to fig. 4, it can be known from the background art that the front baffle, due to its very close distance to the radar (usually within 2 cm), causes very strong reflected energy, and the target object really wanted to be detected (for example, an object at a distance of 0.5 m to 300 m), the reflected energy is much smaller than the energy reflected by the baffle, when the signal of the interfering object in the first signal IF0 is not removed, the interfering object has a larger influence on the signal of the target object, when the signal of the interfering object in the first signal IF0 is partially removed, the interfering object still has an influence on the signal of the target object, when the signal of the interfering object in the first signal IF0 is completely removed, the signal of the target object is obtained, and based on the above carrier cancellation principle, the embodiment of the present application obtains the adjustment signal LOt by adjusting the frequency of the carrier signal LO0, the signal transmitter 20 sends out a detection signal based on the adjustment signal LOt as a carrier, after the carrier stripping is carried out on the reflected signal RF, the reflected energy of an interference object is weakened in the obtained second signal IFt, and the detection quality of the vehicle-mounted radar is greatly improved with smaller power consumption.
It should be noted that fig. 4 is only used for reflecting the influence of the signal of the interfering object on the signal of the target object, and does not constitute a limitation on the waveforms of the target object and the interfering object, and the signal of the target object in the signal shown in fig. 4 is a sawtooth wave with one regular end.
Based on the foregoing, based on adjusting the frequency f M After eliminating the sub-signal corresponding to the interfering object in the reflected signal RF, BCOS (theta) exists g -ω 0 △t+k△t 2 -θ 0 ) In some embodiments, the radar detection system is further configured to cancel the constant term.
Referring to fig. 5, the signal processing module 102 further includes: a fifth processing unit 152 configured to receive and adjust the phase of the carrier signal LO 0; a sixth processing unit 162, connected to the detection module 101, configured to obtain a maximum amplitude of the first signal IF 0; a seventh processing unit 172, connected to the fifth processing unit 152 and the sixth processing unit 162, configured to acquire a variation curve between the maximum amplitude of the first signal and the phase of the carrier signal, and to give the variation curve an acquisition adjustment phase θ M Adjusting the phase theta M The phase corresponding to the maximum amplitude minimum value in the variation curve; the fourth processing unit 142 is further connected to the seventh processingA unit 172 further configured to adjust the phase θ based on M The carrier signal LO0 is adjusted.
Specifically, the fifth processing unit 152, the sixth processing unit 162 and the seventh processing unit 172 are used for continuously adjusting the phase of the carrier signal LO0 to obtain an adjusted phase θ during the test phase M (ii) a The fourth processing unit 142 is further configured to adjust the phase θ based on the obtained phase when the radar detection system is actually applied M Cancellation of signals reflected by interfering objects in the reflected signal RF is performed.
More specifically, the phase of the carrier signal LO0 is continuously adjusted by the fifth processing unit 152, the sixth processing unit 162, and the seventh processing unit 172 to generate the adjustment signal LOt, where LOt is equal to 0 COS(ω 0 t+kt 2 +θ 0 -f M t-△θ)(6)
Based on the operation principle of the mixer 103, IFt ═ RF ═ LOt ═ BCOS [ Δ θ + θ ], (ii) at this time g -ω 0 △t+k△t 2 -θ 0 ]+∑B i COS[(f M -2k△t i )t+△θ+θ g -ω 0 △t i +k△t i 2 -θ 0 ](7)
With respect to equation (7), referring to fig. 6 based on the variation curve between the maximum amplitude a3 of the first signal and the phase θ of the carrier signal, the adjustment phase θ is obtained according to fig. 6 M According to the formula (7) and with reference to FIG. 6, the phase θ is adjusted M ＝ω 0 △t+θ 0 -θ g -k△t 2 + π/2; when the fourth processing unit 142 adjusts the frequency f M And adjusting the phase θ M After adjusting the generated adjusting signal LOt, IFt ═ Sigma B i COS[(2k△t-2k△t i )t+θ M +θ g -ω 0 △t i +k△t i 2 -θ 0 ]I.e. completely eliminating the sub-signals corresponding to the interfering objects in the reflected signal. Namely, on the basis of the adjustment of the frequency of the carrier signal LO0 by the signal processing module 102, the phase adjustment of the carrier signal LO0 is added to completely remove the sub-signal corresponding to the interfering object in the reflected signal, thereby further improving the detection quality of the vehicle-mounted radar.
Referring to fig. 7, in some embodiments, the radar detection system further comprises: an interference cancellation current source 105, disposed on the transmission circuit where the mixer 103 is connected to the baseband circuit 104, and the signal processing module 102 is further configured to: in the first signal IF0, the adjusted phase of the sub-signal corresponding to the interfering object relative to the carrier signal is obtained, the interference cancellation current source 105 is connected to the signal processing module 102, the input terminal is connected to the transmission circuit, and the current value is set based on the amplitude of the carrier signal corresponding to the adjusted phase. As can be seen from the foregoing, BCOS (θ) exists after the sub-signal corresponding to the interfering object is removed g -ω 0 △t+k△t 2 -θ 0 ) When the current source current value is set to BCOS (theta) g -ω 0 △t+k△t 2 -θ 0 ) BCOS (theta) in the second signal IFt g -ω 0 △t+k△t 2 -θ 0 ) The constant current is provided to the interference cancellation current source 105, and at this time, the second signal IFt transmitted to the baseband circuit 104 completely removes the sub-signal corresponding to the interfering object in the reflected signal, thereby further improving the detection quality of the vehicle-mounted radar.
Referring to fig. 8, in some embodiments, a radar detection system, further comprises: and the filter 106 is connected to signal paths of the detection module 101 and the signal processing module 102, and has an input end connected to the detection module 101 and an output end connected to the signal processing module 102. Filtering noise in the first signal IF0 through the filter 106 to increase the acquisition of the conditioning frequency f by the signal processing module 102 M And adjusting the phase θ M The accuracy of (2).
According to the embodiment of the application, the frequency of the carrier signal LO0 is adjusted to obtain the adjusting signal LOt, the signal transmitter 20 sends out a detection signal based on the adjusting signal LOt as a carrier, after carrier stripping is performed on the reflected signal RF, the reflected energy of an interfering object is weakened in the obtained second signal IFt, and the detection quality of the vehicle-mounted radar is greatly improved with low power consumption; in addition, many general radar designs have frequency modulation equipment of a carrier signal LO0, and the method realizes elimination of the reflected energy of the interference object and further reduces power consumption for eliminating the reflected energy of the interference object on the basis of a general radar detection circuit by changing the adjusting method and the connection mode of the frequency modulation equipment.
It should be noted that, in this embodiment, the signal LOt is adjusted to serve as a carrier emission detection signal, but carrier cancellation is still performed based on the carrier signal LO0, which is equivalent to that the measured distance is a parameter such as a distance from an interfering object to a target object, and in a subsequent signal processing process of the radar, the parameter such as the distance between the radar and the target object may be compensated based on the parameter such as the distance between the radar and the interfering object, so as to further improve accuracy of radar positioning.
In practical applications, one logical unit may be one physical unit, may be a part of one physical unit, and may also be implemented by a combination of multiple physical units. In addition, in order to highlight the innovative part of the present disclosure, a unit that is not so closely related to solving the technical problem proposed by the present disclosure is not introduced in the present embodiment, but this does not indicate that there is no other unit in the present embodiment.
It should be noted that the features disclosed in the radar detection systems provided in the above embodiments can be combined arbitrarily without conflict, and a new embodiment of the radar detection system can be obtained.
Another embodiment of this embodiment further provides an interference elimination method, which is applied to the radar detection system provided in the foregoing embodiment, and is used to eliminate the reflected energy of the short-distance obstacle with smaller power consumption, thereby greatly improving the detection quality of the vehicle-mounted radar.
Fig. 9 is a schematic flow diagram of the interference cancellation method provided in this embodiment, and the following describes the interference cancellation method provided in this embodiment in detail with reference to the accompanying drawings, specifically as follows:
referring to fig. 9, an interference cancellation method includes:
The principle of splitting the carrier signal in the reflected signal based on the carrier signal is specifically as follows (the first signal IF0, the carrier signal LO0, the adjustment signal LOt, the reflected signal RF, and the second signal IFt):
specifically, step 202 includes: acquiring a preset value, wherein the preset value is the difference value between the maximum amplitude and the minimum amplitude in the first signal, adjusting the frequency of the carrier signal, acquiring a change curve between the preset value and the frequency of the carrier signal, and acquiring an adjusting frequency based on the change curve, wherein the adjusting frequency is the frequency corresponding to the minimum value of the preset value in the change curve; the working principle of the radar detection system is as follows:
LO0＝A 0 COS(ω 0 t+kt 2 +θ 0 )(1)
RF＝A g COS[ω 0 (t-△t)+k(t-△t) 2 +θ g ]+∑A i COS[ω 0 (t-△t i )+k(t-△t i ) 2 +θ i ](2)
for formula (2) wherein A g COS[ω 0 (t-△t)+k(t-△t) 2 +θ g ]In order to disturb the reflected signal of the object, Σ
A i COS[ω 0 (t-△t i )+k(t-△t i ) 2 +θ i ]Is a reflected signal of the target object; based on the operation principle of the mixer 103, IF0 ═ RF ═ LO0 ═ BCOS [ (-2k Δ t) t + θ [ (-2k Δ t) at this time g -ω 0 △t+k△t 2 -θ 0 ]+∑B i COS[(-2k△t i )t+θ g -ω 0 △t i +k△t i 2 -θ 0 ](3)
As can be seen from the formula (3), the identification signal of the interfering object obtained by removing the carrier from the reflected signal of the interfering object is BCOS [ (-2 k)△t)t+θ g -ω 0 △t+k△t 2 -θ 0 ]I.e. the frequency of the identification signal of the interfering object is-2 k deltat and the phase of the identification signal of the interfering object is theta g -ω 0 △t+k△t 2 -θ 0 。
The frequency of the carrier signal LO0 is continuously adjusted to generate the adjusting signal LOt, which is then equal to 0 COS(ω 0 t+kt 2 +θ 0 -△ωt)(4)
Based on the operation principle of the mixer 103, IFt ═ RF × LOt ═ BCOS [ (. DELTA.. omega. -2 k.DELTA.t) t + θ [ (. DELTA.. omega. -2 k.DELTA.t) ] g -ω 0 △t+k△t 2 -θ 0 ]+∑B i COS[(△ω-2k△t i )t+θ g -ω 0 △t i +k△t i 2 -θ 0 ](5)
For equation (5), the function curve diagram is the variation curve between the preset value A2 and the frequency f of the carrier signal, the variation curve diagram refers to FIG. 3, and the adjustment frequency f is obtained according to FIG. 3 M According to equation (5) and with reference to FIG. 3, the frequency f is adjusted M ＝2k△t。
When according to the regulating frequency f M After adjusting the generated adjustment signal LOt, IFt is BCOS (θ) g -ω 0 △t+k△t 2 -θ 0 )+∑B i COS[(2k△t-2k△t i )t+θ g -ω 0 △t i +k△t i 2 -θ 0 ]Wherein, BCOS (theta) g -ω 0 △t+k△t 2 -θ 0 ) As a constant term, only the amplitude of the second signal IFt is affected, and the frequency of the second signal IFt is not affected, thereby eliminating the signal reflected by the interfering object in the reflected signal RF, and BCOS (θ) g -ω 0 △t+k△t 2 -θ 0 ) As a constant current, it can be removed as a bias current in a subsequent operation.
Based on the carrier wave elimination principle, the frequency of the carrier wave signal is adjusted to obtain the adjusting signal, the signal transmitter serves as the carrier wave to send out the detection signal based on the adjusting signal, after the carrier wave stripping is carried out on the reflection signal, the reflection energy of the interference object is weakened in the obtained second signal, and the detection quality of the vehicle-mounted radar is greatly improved with smaller power consumption.
In some embodiments, step 202 further comprises: acquiring an adjustment phase of a sub-signal corresponding to an interfering object in the first signal relative to the carrier signal, wherein in the process of generating the adjustment signal in step 203, the method further includes: the phase of the carrier signal is adjusted based on the adjusted phase.
In one example, the adjustment signal LOt is generated by continuously adjusting the phase of the carrier signal LO0, when this is done
LOt＝ 0 COS(ω 0 t+kt 2 +θ 0 -f M t-△θ)(6)
Based on the operation principle of the mixer 103, IFt ═ RF ═ LOt ═ BCOS [ Δ θ + θ ], (ii) at this time g -ω 0 △t+k△t 2 -θ 0 ]+∑B i COS[(f M -2k△t i )t+△θ+θ g -ω 0 △t i +k△t i 2 -θ 0 ](7)
With respect to equation (7), referring to fig. 6 based on the variation curve between the maximum amplitude a3 of the first signal and the phase θ of the carrier signal, the adjustment phase θ is obtained according to fig. 6 M According to equation (7) and with reference to FIG. 6, the phase θ is adjusted M ＝ω 0 △t+θ 0 -θ g -k△t 2 + π/2; when according to the regulating frequency f M And adjusting the phase θ M After adjusting the generated adjusting signal LOt, IFt ═ Sigma B i COS[(2k△t-2k△t i )t+θ M +θ g -ω 0 △t i +k△t i 2 -θ 0 ]I.e. completely eliminating the sub-signals corresponding to the interfering objects in the reflected signal.
In some embodiments, step 202 further comprises: acquiring an adjusted phase of a sub-signal corresponding to an interfering object in the first signal relative to the carrier signal, and in the process of inputting the second signal into the baseband circuit 104, step 203 further includes: and the transmission circuit is used for acquiring the interference amplitude of the carrier signal corresponding to the adjusted phase and removing the interference amplitude.
In one example, referring to fig. 7, BCOS (θ) is also present after the sub-signal corresponding to the interfering object is removed g -ω 0 △t+k△t 2 -θ 0 ) When the current source current value is set to BCOS (theta) g -ω 0 △t+k△t 2 -θ 0 ) BCOS (θ) in the second signal IFt g -ω 0 △t+k△t 2 -θ 0 ) The constant current is provided to the interference cancellation current source 105, and at this time, the second signal IFt transmitted to the baseband circuit 104 completely removes the sub-signal corresponding to the interfering object in the reflected signal, thereby further improving the detection quality of the vehicle-mounted radar.
With continued reference to FIG. 9, in some embodiments, there is further included step 204 of compensating the measured distance of the target object based on the adjustment frequency.
Specifically, in the present embodiment, the adjustment signal is used as the carrier wave emission detection signal, but the carrier wave elimination is still performed based on the carrier wave signal, which is equivalent to that the measured distance is a parameter such as a distance between the interfering object and the target object, and the parameter such as a distance between the radar and the target object can be compensated based on the parameter such as a distance between the radar and the interfering object, so as to further improve the accuracy of radar positioning.
It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples of implementations of the present application, and that various changes in form and details may be made therein without departing from the spirit and scope of the present application. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the application, and it is intended that the scope of the application be limited only by the claims appended hereto.
Claims (10)
1. A radar detection system based on a signal transmitter for emitting a probe signal and based on a signal receiver for receiving a reflected signal from an object, comprising:
the signal receiver includes: a mixer, the signal transmitter comprising: a signal processing module;
the detection module is connected with the input end of the baseband circuit and used for acquiring a first signal, wherein the first signal is a signal received by the input end of the baseband circuit;
the signal processing module is connected with the detection module, is used for receiving a carrier signal, and is configured to acquire an adjusting frequency of a sub-signal corresponding to an interfering object in the first signal relative to the carrier signal and adjust the frequency of the carrier signal based on the adjusting frequency to generate an adjusting signal;
the signal transmitter sends out the detection signal based on the adjustment signal;
a mixer for receiving the reflected signal and the carrier signal and coupled to an input of the baseband circuit and configured to mix the reflected signal and the carrier signal to generate a second signal and input the second signal to the baseband circuit.
2. The radar detection system of claim 1, wherein the signal processing module comprises:
a first processing unit configured to receive and adjust a frequency of the carrier signal;
the second processing unit is connected with the detection module and configured to acquire a preset value, wherein the preset value is a difference value between a maximum amplitude and a minimum amplitude in the first signal;
a third processing unit, connected to the first processing unit and the second processing unit, configured to obtain a variation curve between the preset value and the frequency of the carrier signal, and obtain the adjustment frequency based on the variation curve, where the adjustment frequency is a frequency corresponding to a minimum value of the preset value in the variation curve;
and the fourth processing unit is connected with the third processing unit and receives the carrier signal, and is configured to adjust the carrier signal based on the adjusting frequency and generate the adjusting signal.
3. The radar detection system of claim 2, wherein the signal processing module further comprises:
a fifth processing unit configured to receive and adjust a phase of the carrier signal;
the sixth processing unit is connected with the detection module and configured to acquire the maximum amplitude of the first signal;
a seventh processing unit, connected to the fifth processing unit and the sixth processing unit, configured to obtain a variation curve between a maximum amplitude of the first signal and a phase of the carrier signal, and obtain an adjustment phase based on the variation curve, where the adjustment phase is a phase corresponding to a minimum value of the maximum amplitude in the variation curve;
the fourth processing unit is further connected to the seventh processing unit and configured to adjust the carrier signal based on the adjusted phase.
4. The radar detection system of claim 2, further comprising: the interference cancellation current source is arranged on a transmission circuit of the frequency mixer connected with the baseband circuit;
the signal processing module is further configured to: acquiring the adjusting phase of a sub-signal corresponding to an interfering object in the first signal relative to the carrier signal;
the interference cancellation current source is further connected with the signal processing module, the input end of the interference cancellation current source is connected with the transmission circuit, and the current value is set based on the amplitude of the carrier signal corresponding to the adjusting phase.
5. The radar detection system of claim 1, further comprising: and the filter is connected on a signal path between the detection module and the signal processing module, the input end of the filter is connected with the detection module, and the output end of the filter is connected with the signal processing module.
6. An interference cancellation method applied to the radar detection system according to any one of claims 1 to 5, comprising:
acquiring a first signal received by a baseband circuit, and acquiring the adjusting frequency of a sub-signal corresponding to an interfering object in the first signal relative to a carrier signal;
acquiring a carrier signal, adjusting the frequency of the carrier signal based on the adjusting frequency, and generating an adjusting signal;
sending a detection signal by taking the adjustment signal as a carrier, and receiving a reflected signal generated by a target object reflecting the detection signal;
and stripping a carrier in the reflected signal based on the carrier signal, generating a second signal, and inputting the second signal to the baseband circuit.
7. The method according to claim 6, wherein the obtaining an adjusted frequency or an adjusted phase of the sub-signal corresponding to the interfering object in the first signal with respect to the carrier signal comprises:
acquiring a preset value, wherein the preset value is the difference value between the maximum amplitude and the minimum amplitude in the first signal;
and adjusting the frequency of a carrier signal, acquiring a variation curve between the preset value and the frequency of the carrier signal, and acquiring the adjusting frequency based on the variation curve, wherein the adjusting frequency is the frequency corresponding to the minimum value of the preset value in the variation curve.
8. The method according to claim 6, wherein the obtaining an adjusted frequency or an adjusted phase of the sub-signal corresponding to the interfering object in the first signal with respect to the carrier signal further comprises:
acquiring an adjusting phase of a sub-signal corresponding to an interfering object in the first signal relative to a carrier signal;
in the process of generating the adjustment signal, the method further includes: adjusting a phase of the carrier signal based on the adjusted phase.
9. The method according to claim 6, wherein the obtaining an adjusted frequency or an adjusted phase of the sub-signal corresponding to the interfering object in the first signal with respect to the carrier signal further comprises:
acquiring an adjusting phase of a sub-signal corresponding to an interfering object in the first signal relative to a carrier signal;
in the process of inputting the second signal to the baseband circuit, the method further includes: and acquiring the interference amplitude of the carrier signal corresponding to the adjusting phase, and removing the transmission current of the interference amplitude.
10. The interference cancellation method according to claim 6, wherein after the inputting the second signal to the baseband circuit, further comprising: compensating a measured distance of a target object based on the adjusted frequency, the measured distance being obtained by the baseband circuitry based on the second signal.
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