CN117295966A

CN117295966A - Detection system, terminal equipment and detection method

Info

Publication number: CN117295966A
Application number: CN202180097931.6A
Authority: CN
Inventors: 张慧; 马莎; 宋思达
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-05-27
Filing date: 2021-05-27
Publication date: 2023-12-26
Also published as: WO2022246772A1

Abstract

A detection system, a terminal device and a detection method can be applied to the fields of automatic driving or intelligent driving and the like. The detection system may be a radar, comprising: a transmitting module (301) for transmitting a first signal comprising N first sub-band signals, a frequency spacing between at least two of the N first sub-band signals being larger than a frequency threshold; a receiving module (302) for receiving echo signals reflected by the target on the first signal, the echo signals comprising N second subband signals; and the processing module (303) is used for determining a scattering center geometric factor of the target according to the echo signals, and carrying out frequency compensation on the N second sub-band signals according to the scattering center geometric factor so as to enable the scattering characteristics of the N second sub-band signals to be consistent, thereby determining the distance information of the target according to the N compensated second sub-band signals. The detection method can also be applied to the Internet of vehicles, such as the vehicle external connection V2X, the vehicle-vehicle V2V and the like.

Description

Detection system, terminal equipment and detection method

Technical Field

The present disclosure relates to the field of detection technologies, and in particular, to a detection system, a terminal device, and a detection method.

Background

Along with the development of informatization, intelligent terminals gradually enter people's daily life. Sensing systems play an increasingly important role in intelligent terminals. Radar in a sensing system is one of hot spots of current research because of its high reliability, long distance and high precision measurement performance to the external environment.

Range resolution is a relatively important functional parameter of radar. The distance resolution refers to resolution of a distance dimension, that is, the minimum distance that two targets can be resolved, and the smaller the minimum distance that two targets can be resolved, the higher the distance resolution. The range resolution of the radar is determined by the bandwidth of the transmitted signal, and a high range resolution requires a larger bandwidth of the transmitted signal. But continuous large bandwidth transmit signals are more difficult to implement and have higher cost requirements; moreover, the continuous large bandwidth needs complete continuous spectrum resources, which are limited by the policy of issuing spectrum resources, and the continuous spectrum resources are difficult to be ensured. One approach to addressing the broadband is to use multiple narrowband transmit-receive signals for processing to obtain the equivalent large bandwidth effect, such as using a frequency step radar or a frequency modulated step radar. But the frequency separation between adjacent sub-bands of the frequency step radar or frequency modulated step radar cannot be too large, otherwise the estimated maximum range of unambiguous distances becomes small. Specifically: the condition of not generating distance blur is Or Δf is less than or equal to B ₀ Wherein Δf is the frequency spacing between adjacent uniform stepping subbands, T _p Representing the duration of a single pulse signal, B ₀ Representing the bandwidth of one chirp. At the same time, the maximum frequency interval between the sub-bands in the method is smaller relative to the carrier frequency, oneTypically meeting a narrow band hypothesis range. In practice, however, there are a large number of scattered spectrum resources whose frequency intervals may be large and whose influence on the target scattering properties by these different sub-bands with large frequency intervals is not negligible.

In summary, how to use a sparse subband with a larger frequency span to perform wideband synthesis to obtain target distance information with higher resolution is a technical problem to be solved currently.

Disclosure of Invention

The application provides a detection system, a terminal device and a detection method, which are used for broadband synthesis by utilizing a sparse sub-band with a larger frequency span so as to obtain target distance information with higher resolution.

In a first aspect, the present application provides a detection system that may include a transmit module, a receive module, and a processing module. The transmitting module is used for transmitting first signals, the first signals can comprise N first sub-band signals, and the frequency interval between at least two first sub-band signals in the N first sub-band signals is larger than a frequency threshold value; the receiving module is used for receiving echo signals, wherein the echo signals comprise N second sub-band signals, and the echo signals are signals received by the detection system after the first signals are reflected by the target; the processing module is used for determining a scattering center geometric factor of the target according to the echo signals, performing frequency compensation on the received N second sub-band signals according to the scattering center geometric factor, and determining distance information of the target according to the N compensated second sub-band signals. The N first sub-band signals and the N second sub-band signals are one-to-one signals.

Based on the scheme, the second sub-band signals are subjected to frequency compensation according to the geometric factors of the scattering centers of the targets, so that the target scattering characteristics of N second sub-band signals are consistent, and the distance information of the targets can be determined according to the N compensated second sub-band signals.

In a possible implementation, the processing module is specifically configured to multiply the nth second subband signal by the compensation factor Wherein,the nth second sub-band signal is any one of the N second sub-band signals, Δf, as a scattering center geometry factor _n Initial frequency f for the nth second sub-band signal and the lowest frequency second sub-band signal ₀ Frequency spacing between.

By multiplying each second subband signal by a compensation factorThereby eliminating the influence of the scattering property of the object on the second subband signal.

In one possible implementation, any two first frequency interval ratios satisfy a prime ratio, the first frequency interval being a frequency interval between a first sub-band signal and a reference band signal; the reference frequency band signal is the first sub-band signal with the lowest frequency in the N first sub-band signals.

In one possible implementation, the frequency separation between the ith first sub-band signal and the reference band signal is equal to n of the reference frequency step amount _i The ith first sub-band signal is one of the N first sub-band signals; wherein the reference frequency step amount is inversely proportional to the maximum unblurred distance.

Because the first frequency interval ratio meets the prime ratio, the positions of the fuzzy distances corresponding to the first sub-band signals are different, and when the distance estimation results corresponding to all the first sub-band signals are intersected, all the fuzzy distances are not existed, and only the true distances are left. In other words, when the first frequency interval ratio satisfies the prime ratio, no additional distance ambiguity is generated.

In one possible implementation, the N first subband signals correspond to H sets, the sets comprising at least two first subband signals, H being an integer greater than 1; wherein the third frequency interval is equal to (N of the second frequency interval _k +1) times, the third frequency interval being the frequency interval between any two adjacent first sub-band signals in the kth+1th set, the second frequency interval being the frequency interval between any two adjacent first sub-band signals in the kth set, N _k Is the number of first subbands included in the kth set.

By setting the sparse N first subband signals with the above characteristics, the maximum non-ambiguity distance can be kept unchanged, and a larger bandwidth can be obtained.

In one possible implementation, the processing module is specifically configured to: performing sum/difference processing on the compensated N second sub-band signals to obtain P virtual sub-band signals, wherein P is an integer greater than N; and determining the distance information of the target according to the P virtual sub-band signals.

In one possible implementation, when h=2, k=1:

wherein N is ₁ For the number of first subband signals comprised by the first set, N ₂ For the number of first subband signals comprised by the second set.

In one possible implementation, the P virtual subband signals include virtual subband signals j times the reference frequency step by j taking { -N ₂ (N ₁ +1)-1,….,N ₂ (N ₁ +1) -1 }.

The continuous and uniform P virtual sub-band signals can be obtained through the sum/difference processing, and the continuous and uniform (namely, the virtual sub-band signals can be regarded as non-sparse) virtual sub-band signals are utilized for distance estimation, so that the effects of unchanged maximum non-fuzzy distance, increased freedom and reduced side lobe can be achieved.

In one possible implementation, the N first subband signals correspond to M sets, the sets comprising at least two first subband signals, M being an integer greater than 1; the mth set includes N _m A first subband signal, an m+1th set including N _m+1 First sub-band signals, N _m+1 And N _m The M-th set and the m+1th set are two sets in M sets; the fourth frequency interval is equal to N of the reference frequency step amount _m+1 The fourth frequency interval is the frequency interval between any two adjacent first sub-band signals in the mth set; the reference frequency step size is inversely proportional to the maximum unblurred distance; the fifth frequency interval is equal to N of the reference frequency step amount _m The fifth frequency interval is the frequency interval between any two adjacent first sub-band signals in the m+1th set, and p is a positive integer.

In one possible implementation, the initial frequency of the lowest frequency first subband signal in the mth set coincides with the initial frequency of the lowest frequency first subband signal in the m+1th set.

In one possible implementation, the mth set and the m+1th set are any two adjacent sets of the M sets, and a frequency interval between the first sub-band signal with the highest frequency in the mth set and the first sub-band signal with the lowest frequency in the m+1th set is equal to L times of a reference frequency stepping amount, where L is a positive integer.

In one possible implementation, L is N _m And N _m+1 Is the minimum value of (a).

Taking N through L _m And N _m+1 A greater number of consecutive virtual subband signals may be obtained.

In one possible implementation, the processing module is specifically configured to: performing sum/difference processing on the compensated N second sub-band signals to obtain Q virtual sub-band signals, wherein Q is an integer greater than N; and determining the distance information of the target according to the Q virtual sub-band signals.

The partial continuous and uniform virtual sub-band signals can be obtained through the sum/difference processing, and the continuous and uniform (namely, the virtual sub-band signals can be regarded as non-sparse) virtual sub-band signals are utilized for distance estimation, so that the effects of unchanged maximum non-fuzzy distance, increased freedom and reduced side lobe can be achieved.

In one possible implementation, the transmitting module is a single transmitting antenna; the transmitting module is specifically used for: the N first sub-band signals are transmitted at different times.

In one possible implementation, the transmitting module is a plurality of transmitting antennas; the transmitting module is specifically used for: transmitting N first sub-band signals at the same time instant; alternatively, the N first sub-band signals are transmitted at different times.

In a second aspect, the present application provides a terminal device, including the detection system of the first aspect or any one of the first aspects, and a processor, where the processor is configured to process distance information determined by the detection system.

In a third aspect, the present application provides a method of detection, the method comprising receiving an echo signal; the echo signals comprise N second sub-band signals, the echo signals are signals received by the detection system after the first signals are reflected by the target, the first signals comprise N first sub-band signals, and the frequency interval between at least two first sub-band signals in the N first sub-band signals is larger than a frequency threshold; determining a scattering center geometric factor of the target according to the echo signal; performing frequency compensation on the N second sub-band signals according to the geometric factors of the scattering centers; and determining the distance information of the target according to the N compensated second sub-band signals.

The method may be performed by the first aspect or any one of the detection systems of the first aspect; or may be performed by any one of the terminal devices of the second or first aspects described above.

In one possibilityIn an implementation of (2) multiplying the nth second sub-band signal by a compensation factor n is an integer greater than 1; wherein,the nth second sub-band signal is any one of the N second sub-band signals, Δf, as a scattering center geometry factor of the target _n Initial frequency f for the nth second sub-band signal and the lowest frequency second sub-band signal ₀ Frequency spacing between.

In one possible implementation, any two first frequency interval ratios satisfy a prime ratio, the first frequency interval being a frequency interval between the first sub-band signal and the reference band signal; the reference frequency band signal is the first sub-band signal with the lowest frequency in the N first sub-band signals.

In one possible implementation, the N first subband signals correspond to H sets, the sets comprising at least two first subband signals, H being an integer greater than 1; wherein the third frequency interval is equal to (N of the second frequency interval _k +1) times, a third frequency interval being a frequency interval between any two adjacent first subband signals in the kth set +1, a third frequency interval being a frequency interval between any two adjacent first subband signals in the kth set, N _k Is the number of first subbands included in the kth set.

In one possible implementation, the N first subband signals correspond to M sets, the sets comprising at least two first subband signals, M being an integer greater than 1; the mth set includes N _m A first subband signal, an m+1th set including N _m+1 First sub-band signals, N _m+1 And N _m The M-th set and the m+1th set are two sets in M sets; the fourth frequency interval is equal to the referenceN of the step of the test frequency _m+1 The fourth frequency interval is the frequency interval between any two adjacent first sub-band signals in the mth set; the reference frequency step size is inversely proportional to the maximum unblurred distance; the fifth frequency interval is equal to N of the reference frequency step amount _m The fifth frequency interval is the frequency interval between any two adjacent first sub-band signals in the m+1th set, and p is a positive integer.

In one possible implementation manner, performing sum/difference processing on the compensated N second subband signals to obtain H virtual subband signals, where H is an integer greater than N; and determining the distance information of the target according to the H virtual sub-band signals.

Further, optionally, vectorizing the covariance matrix of the compensated N second subband signals, and then processing the H virtual subband signals by adopting a smooth multiple signal classification MUSIC algorithm to obtain the distance information of the target.

In one possible implementation, the N first subband signals are transmitted at different times; alternatively, the N first sub-band signals are transmitted at the same time.

In a fourth aspect, the present application provides a computer readable storage medium having stored therein a computer program or instructions which, when executed by a detection system, cause the detection system to perform the method of the third aspect or any possible implementation of the third aspect.

In a fifth aspect, the present application provides a computer program product comprising a computer program or instructions which, when executed by a detection system, cause the detection system to perform the method of the third aspect or any of the possible implementations of the third aspect.

Drawings

Fig. 1 is a schematic diagram of a possible application scenario of a radar provided in the present application;

fig. 2 is a schematic diagram of another possible application scenario of the radar provided in the present application;

FIG. 3 is a schematic diagram of a detection system according to the present disclosure;

fig. 4a is a frequency distribution diagram of N first subband signals provided in the present application;

fig. 4b is a schematic frequency distribution diagram of another N first subband signals provided in the present application;

fig. 5a is a schematic diagram of a time division mode distribution of N first subband signals provided in the present application;

Fig. 5b is a schematic diagram of a time division mode distribution of another N first subband signals provided in the present application;

FIG. 5c is a schematic diagram illustrating a distribution of frequency division modes of N first subband signals provided herein;

fig. 5d is a schematic diagram illustrating a distribution of frequency division modes of another N first subband signals provided in the present application;

fig. 6a is a frequency distribution diagram of N first subband signals provided in the present application;

fig. 6b is a schematic frequency distribution diagram of another N first subband signals provided in the present application;

fig. 7a is a schematic diagram of a time division mode distribution of N first subband signals provided in the present application;

fig. 7b is a schematic diagram of a time division mode distribution of another N first subband signals provided in the present application;

fig. 7c is a schematic diagram illustrating a distribution of frequency division modes of another N first subband signals provided in the present application;

fig. 7d is a schematic diagram illustrating a distribution of frequency division modes of another N first subband signals provided in the present application;

fig. 8a is a frequency distribution diagram of N first subband signals provided in the present application;

fig. 8b is a frequency distribution diagram of another N first subband signals provided in the present application;

fig. 9a is a schematic diagram of a time division mode distribution of N first subband signals provided in the present application;

Fig. 9b is a schematic diagram of a time division mode distribution of another N first subband signals provided in the present application;

FIG. 9c is a schematic diagram illustrating a distribution of frequency division modes of N first subband signals provided herein;

fig. 9d is a schematic diagram illustrating a distribution of frequency division modes of another N first subband signals provided in the present application;

fig. 10a is a schematic diagram of a time division mode distribution of N first subband signals provided in the present application;

FIG. 10b is a schematic diagram of a time division mode distribution of another N first subband signals provided herein;

FIG. 10c is a schematic diagram illustrating a distribution of frequency division modes of N first subband signals provided herein;

FIG. 10d is a schematic diagram illustrating a distribution of frequency division modes of another N first sub-band signals provided in the present application;

fig. 11 is a schematic structural diagram of a receiving module provided in the present application;

fig. 12 is a frequency distribution diagram of N second subband signals provided in the present application;

fig. 13 is a frequency distribution diagram of N second subband signals provided in the present application;

fig. 14 is a flow chart of a detection method provided in the present application.

Detailed Description

Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Hereinafter, some terms in the present application will be explained. It should be noted that these explanations are for the convenience of those skilled in the art, and do not limit the scope of protection claimed in the present application.

1. Distance resolution

Distance resolution refers to the resolution of the distance dimension, i.e., the smallest distance that two objects can be recognized. Taking the echo signal as an example of a pulse signal, when the trailing edge (falling edge) of the echo pulse of the closer target is just overlapped with the leading edge (rising edge) of the echo of the farther target, the trailing edge is taken as a resolvable limit, and the distance between the two targets is the distance resolution.

In the radar image, when two targets are located at the same azimuth angle but at different distances from the radar, the minimum distance between the two targets is the distance resolution. The range resolution of a radar is defined as the radar's ability to resolve two close range targets. The range resolution of the radar is related to the pulse width of the radar transmission signal, and the narrower the pulse width of the radar transmission signal is, the higher the range resolution of the radar is. In general, the range resolution of radar can be used ρ _r For representation, see equation 1 below.

ρ _r ＝c/2B _e Equation 1

Wherein B is _e Is the bandwidth of the radar transmit signal. As can be seen from the above equation 1, the larger the transmission signal bandwidth, the higher the range resolution of the radar.

2. Maximum distance without ambiguity

Maximum disambiguation distance (r) _max ) Meaning that when one pulse signal transmitted by the radar encounters a backscattered wave (i.e. echo signal) reflected by a target at that distance back to the radar, the next pulse signal is just emitted. That is, the time taken for a pulse signal transmitted by the radar to propagate to a target located at a maximum unambiguous distance and then return to the radar is just the time interval between two pulse signals.

Illustratively, if the radar transmits a first pulse signal that is reflected by a target at 200m and an echo signal for the first pulse signal is received by the radar before the second pulse signal is transmitted, then the radar determines that there is no ambiguity in the range information for this target. If the first pulse signal is reflected by the target at 400m, the radar has transmitted the second pulse signal, and the echo signal for the first pulse signal is received by the radar, and at this time, the radar cannot determine whether the received echo signal is the echo signal for the first pulse signal or the echo signal for the second pulse signal on the premise of no other additional information, that is, the radar determines the distance information of the target, that is, the ambiguity exists, that is, the distance ambiguity is generated.

3. Reference frequency step size

The reference frequency step amount may be a reference value that measures the frequency offset of each sub-band signal with respect to the reference band signal.

Illustratively, the reference frequency step amount Δf is a distance r from the maximum blur _max Satisfying the following equation 2.

r _max =c/2 Δf equation 2

4. Frequency band

The frequency band refers to the frequency resource occupied by a signal and may be described by the initial frequency (or referred to as the lowest frequency) and the frequency bandwidth of the occupied frequency spectrum resource, or by the center frequency and the frequency bandwidth of the occupied frequency spectrum resource. The bandwidth, i.e. bandwidth, for a segment of contiguous frequency resources, the bandwidth refers to the difference between the highest frequency and the lowest frequency of the segment of frequency resources. Wherein the initial frequency is the lowest frequency in the frequency band.

5. Chirp (Chirp)

Chirp is a term in the art of communication related to coded pulse technology that refers to the fact that the carrier frequency of a pulse increases linearly over the duration of the pulse as it is coded. A phenomenon in which the center wavelength is shifted during pulse transmission is generally called "chirp".

6. Frequency step signal

Consists of a series of transmission pulse signals with carrier frequency linear jump.

7. Frequency modulation stepping

The single transmitted pulse signal in the frequency stepping signal is a chirp signal, so the frequency stepping signal has the advantages of both the chirp signal and the frequency stepping signal.

Based on the foregoing, possible application scenarios of the present application are described below. In the following description, a detection system is taken as an example of radar, and a possible application scenario of the detection system is described.

Fig. 1 is a schematic diagram of a possible application scenario of a radar provided in the present application. The radar transmits signals in a certain direction, and if a target exists at a certain distance along the transmission direction of the signals, the target can reflect the received signals back to the radar (called echo signals), and the radar can determine information of the target according to the echo signals, such as the distance of the target, the moving speed of the target, the gesture of the target or a point cloud image. It should be appreciated that the radar may be deployed at various locations of the vehicle, for example, in four directions, front, rear, left and right, to achieve omni-directional capture of the vehicle surroundings. In fig. 1, a radar disposed at the front end of a vehicle is illustrated, and the radar senses a sector area, which may be referred to as a detection area of the radar, as indicated by a dotted line frame.

The application scene can be applied to the fields of unmanned driving, automatic driving, auxiliary driving, intelligent driving, internet-connected vehicles and the like. In this scenario, the radar may be mounted on a vehicle (e.g., an unmanned vehicle, a smart vehicle, an electric vehicle, a digital car, etc.), as an in-vehicle radar. The vehicle-mounted radar can acquire the detected measurement information such as longitude and latitude, speed, direction, distance of surrounding objects and the like of the vehicle in real time or periodically, and then realize auxiliary driving or unmanned driving of the vehicle and the like according to the measurement information and in combination with an advanced driving auxiliary system (advanced driving assistant system, ADAS). For example, the position of the vehicle is determined using longitude and latitude, or the direction and destination of travel of the vehicle for a future period of time is determined using speed and orientation, or the number, density, etc. of obstacles around the vehicle is determined using the distance of surrounding objects. Alternatively, in this scenario, the radar may also be mounted on the drone as an airborne radar. Alternatively, the radar may be mounted on a Road Side Unit (RSU) (see fig. 2) as a road side traffic radar, so that intelligent vehicle-road cooperation may be realized.

It should be noted that the above application scenario is merely an example, and the radar provided in the present application may also be applied to a variety of other possible scenarios, and is not limited to the scenario illustrated in the foregoing example. For example, the radar may also be applied to a terminal device or a component provided in the terminal device, and the terminal device may be, for example, a smart phone, a smart home device, a smart manufacturing device, a robot, an unmanned plane, or a smart transport device (such as an automated guided vehicle (automated guided vehicle, AGV), or an unmanned vehicle, etc.), etc. Among them, the AGV car refers to a transport vehicle equipped with an electromagnetic or optical automatic navigation device, capable of traveling along a predetermined navigation path, and having safety protection and various transfer functions.

In one possible implementation, the radar may be classified into a Long Range Radar (LRR), a medium range radar (middle range radar, MRR), and a short range radar (short range radar, SRR) based on different measurement ranges. The LRR has ranging and anti-collision functions, and is widely applied to the fields of adaptive cruise control (adaptive cruise control, ACC), forward collision warning (forward collision warning, FCW), automatic emergency braking (automatic emergency brake, AEB) and the like. Illustratively, the LRR may be installed at the very center position of the front bumper of the vehicle with an azimuth angle of 0 °, and an elevation angle may be set to 1.5 ° when the height is below 50 cm; when the height exceeds 50cm, the elevation angle is set to be 0 degrees, so that the moving object detection capability of 150 meters of trucks, 100 meters of automobiles and 60 meters of pedestrians can be realized. The functions of the LRR ACC, FCW, AEB and the like have remarkable safety prompt effect when a driver is distracted, tired, or fails to notice the front situation by using a mobile phone and the like. The MRR and SRR have the functions of blind spot detection (blind spot detection, BSD), lane change assistance (lane change assistance, LCA), backward target crossing warning (rear cross traffic alert, RCTA), door opening assistance (exit essistant function, EAF), forward target crossing warning (forward cross traffic alert, FCTA) and the like, and can accurately detect targets within a certain range of the front, rear, left and right of the vehicle. As a typical application in an ADAS system, the SRR can effectively reduce the risk coefficient caused by inconvenient observation of a driver in severe weather conditions such as night, foggy weather, heavy rain and the like in the fields of BSD, LCA and the like, and avoid the risk of possible collision between adjacent lanes and blind areas of 'vision' in the course of parallel operation of the driver.

As described in the background art, when wideband synthesis is performed using sparse subbands with a large frequency span, the difference in scattering characteristics of the targets introduced by the frequencies affects the estimated distance information of the targets.

In view of this, the present application proposes a detection system. The detection system proposed in the present application will be specifically described with reference to fig. 3 to 12.

Fig. 3 is a schematic structural diagram of a detection system provided in the present application. The detection system may include a transmit module 301, a receive module 302, and a processing module 303. The transmitting module 301 is configured to transmit a first signal, where the first signal includes N first subband signals, and a frequency interval between at least two first subband signals in the N first subband signals is greater than a frequency threshold, where the frequency threshold is related to an initial frequency of the first subband signals, and the greater the initial frequency, the greater the frequency threshold. The ratio of the frequency threshold to the initial frequency may be represented by a preset value, which may be a positive number greater than 0.1, for example, 0.5, 0.8, 1, 1.2,1.5, 2, etc. The receiving module 302 is configured to receive an echo signal, where the echo signal includes N second subband signals, and the echo signal is a signal received by the radar after the echo signal reflects the first signal. The processing module 303 is configured to determine a scattering center geometry factor of the target according to the echo signal According to scattering center geometry factorAnd carrying out frequency compensation on the received N second sub-band signals, and determining the distance information of the target according to the N compensated second sub-band signals. Wherein,is related to the geometry of the target, typically an integer multiple of 1/2.

It should be noted that, performing frequency compensation on the received N second subband signals includes: performing frequency compensation on a second sub-band signal with a frequency interval larger than a frequency threshold value in the received N second sub-band signals, wherein the second sub-band signal with the frequency interval not larger than the frequency threshold value can be compensated; or, frequency compensation is performed on a second sub-band signal with a frequency interval greater than a frequency threshold value in the received N second sub-band signals, and no processing is performed on the second sub-band signal with a frequency interval not greater than the frequency threshold value. It is also understood that the compensated N second subband signals may be partly compensated second subband signals or may be entirely compensated second subband signals.

Based on the detection system, the geometrical factors of the scattering center based on the target are utilizedAnd frequency compensation is carried out on the second sub-band signals, so that the scattering characteristics of the targets of the N second sub-band signals are consistent, and the distance information of the targets can be determined according to the N compensated second sub-band signals.

In one possible implementation, the N first subband signals may be the same radar emission or may be different radar emissions. For example, may be both 77 gigahertz (GHz) radar transmissions, may be both 140GHz radar transmissions, or may be both 77GHz radar and 140GHz radar transmissions. That is, the detection system may include a single radar, or may also include a combination of multiple radars.

The following description describes the respective functional modules shown in fig. 2 to give an exemplary implementation. For convenience of description, the transmitting module, the receiving module and the processing module are not identified.

1. And a transmitting module.

In one possible implementation, the transmitting module may be configured to transmit the first signal to the detection region, where the first signal may include sparse N first subband signals.

Three possible configurations of sparse N first sub-band signals are exemplarily shown below.

In the first structure, the N first subband signals are nested.

In one possible implementation, the N first subband signals correspond to H sets, H being an integer greater than 1, each set comprising at least two first subband signals; taking two sets of the H sets as an example, namely the (k+1) th set and the (k) th set as an example, the third frequency interval between any adjacent two first subband signals of the (k+1) th set is equal to (N) of the second frequency interval between any adjacent two first subband signals of the (k) th set _k +1) times, N _k Is the number of first subband signals included in the kth set. The frequency difference between the lowest frequency first sub-band signal in the k+1th set and the highest frequency first sub-band signal in the k set is equal to the second frequency interval.

It is also understood that the second frequency interval between any two adjacent first subband signals in the kth set is Δf _k The kth set includes a first number of subbands of N _k The third frequency interval between any adjacent two of the first subband signals in the k+1th set is (N) _k +1)×Δf _k . Wherein each set includes a uniform frequency step or a uniform frequency modulated step of the first sub-band signal.

The frequency interval between any two adjacent sets is different, and the frequency interval between two adjacent sets may be understood as the interval between the first subband signal of the highest frequency in the former set and the first subband signal of the lowest frequency in the latter set.

As follows, two-stage nesting of N first subband signals is taken as an example, i.e. h=2.

In one possible implementation, for the N first subband signals, the two-level nested set may be allocated N first subband signals based on the following relationship. Wherein N is ₁ For the number of first subband signals comprised by the first level set, N ₂ For the number of first subband signals comprised by the second level set.

As shown in fig. 4a, a frequency distribution diagram of another N first sub-bands is provided in the present application. Fig. 4a exemplifies two-level nesting, namely level 1 and level 2 sets. Wherein the second frequency interval Deltaf between any two adjacent first sub-band signals in the level 1 set ₁ The number of first subband signals included in the level 1 set is N ₁ Third frequency interval Deltaf between any two adjacent first sub-band signals in the level 2 set ₂ ＝(N ₁ +1)Δf ₁ The number of first subband signals included in the level 2 set is N ₂ . The frequency difference between the lowest frequency first sub-band signal in stage 1 and the highest frequency first sub-band signal in stage 2 is equal to the second frequency interval deltaf ₁ 。

It should be noted that fig. 4a is an example of frequency modulation step, and may be a frequency step, as shown in fig. 4b.

When the N first subband signals are frequency stepped, the N first subband signals shown in fig. 4a may be a time-division mode distribution (see fig. 5 a) or may be a frequency-division mode distribution (see fig. 5 c). When the N first sub-band signals are frequency-modulated in steps, the N first sub-band signals shown in fig. 4b may be a time-division mode distribution (see fig. 5 b) or may be a frequency-division mode distribution (see fig. 5 d).

It should be noted that the initial frequency or the center frequency or the end frequency of each first sub-band in the level 1 set is used Representing the initial or center or end frequency of each first sub-band in the level 2 nested set

In the second structure, the N first subband signals are prime II types.

In one possible implementation, the N first subband signals correspond to M sets, each set comprising at least two first subband signals, M being an integer greater than 1.

Taking two of the M sets as examples, namely the mth set and the (m+1) th set as examples. The mth set includes N _m A first subband signal, an m+1th set including N _m+1 First sub-band signals, N _m+1 And N _m Mutually good quality. The fourth frequency interval between any two adjacent first sub-band signals in the m th set is equal to N of the reference frequency step amount _m+1 The fifth frequency interval between any two adjacent first sub-band signals in the (m+1) th set is equal to N of the reference frequency step amount _m And p is a positive integer.

When p=1, the mth set includes N _m A first subband signal, an m+1th set including N _m+1 First sub-band signals, N _m+1 And N _m Mutually good quality. The fourth frequency interval between any two adjacent first sub-band signals in the m th set is equal to N of the reference frequency step amount _m+1 The fifth frequency interval between any two adjacent first subband signals in the m+1th set is equal to N of the reference frequency step amount _m Multiple times.

Based on the positional relationship of the mth set and the (m+1) th set, the following two cases can be introduced.

In case one, the initial frequency of the first subband signal with the lowest frequency in the mth set coincides with the initial frequency of the first subband signal with the lowest frequency in the m+1th set.

As shown in fig. 6a, a frequency distribution diagram of N first subband signals is provided. In this example, taking m=2 as an example, N first subband signals correspond to 2 sets (set 1 and set 2, respectively). Set 1 includes N ₁ A first sub-band signal, set 2 comprising N ₂ The fourth frequency interval between any two adjacent first sub-band signals in the set 1 is delta f ₁ ＝N ₂ Δf, the fifth frequency interval between any two adjacent first subband signals in set 2 is Δf ₂ ＝N ₁ Δf，N ₁ And N ₂ Mutual mass, f ₁ And f ₁ ' coincidence, i.e. initial frequency f of the lowest frequency first subband signal in set 1 ₁ Initial frequency f of first sub-band signal with lowest frequency in set 2 ₁ 'coincidence'.

It should be noted that fig. 6a is an example of frequency stepping, and may be a frequency-modulated stepping, as shown in fig. 6b.

When the N first subband signals are frequency stepped, the N first subband signals shown in fig. 6a may be a time-division mode distribution (see fig. 7 a) or may be a frequency-division mode distribution (see fig. 7 c). When the N first sub-band signals are frequency-modulated in steps, the N first sub-band signals shown in fig. 6b may be a time-division mode distribution (see fig. 7 b), or may be a frequency-division mode distribution (see fig. 7 d).

In the second case, the frequency interval between the first sub-band signal with the highest frequency in the mth set and the first sub-band signal with the lowest frequency in the (m+1) th set is equal to L times of the reference frequency step amount, and L is a positive integer.

Based on the second case, the mth set and the (m+1) th set are any adjacent two sets among the M sets. Further, optionally, L.gtoreq.min { N _m ，N _m+1 "L takes N _m And N _m+1 Is the minimum value of (a). In this way, a greater number of consecutive virtual sub-band signals may be obtained.

As shown in fig. 8a, another frequency distribution diagram of N first subband signals provided in the present application is shown. Taking m=2 as an example in this example, i.e. the N first subband signals correspond to 2 sets (set 3 and set 4, respectively), set 3 comprises N ₁ A first sub-band signal, set 4 comprising N ₂ The fourth frequency interval between any two adjacent first sub-band signals in the set 3 is delta f ₃ ＝N ₂ The fifth frequency interval between any two adjacent first sub-band signals in the set 4 is Δf ₄ ＝N ₁ Δf，N ₁ And N ₂ The frequency interval between the set 3 and the set 4 is equal to L times the reference frequency step amount, i.e. the frequency interval between the first sub-band signal of the highest frequency in the set 3 and the first sub-band signal of the lowest frequency in the set 4 is equal to L times the reference frequency step amount.

It should be noted that fig. 8a is an example of frequency stepping, and may also be frequency-modulated stepping, as shown in fig. 8b.

When the N first subband signals are frequency stepped, the N first subband signals shown in fig. 8a may be a time-division mode distribution (see fig. 9 a) or may be a frequency-division mode distribution (see fig. 9 c). When the N first sub-band signals are frequency-modulated in steps, the N first sub-band signals shown in fig. 8b may be a time-division mode distribution (see fig. 9 b), or may be a frequency-division mode distribution (see fig. 9 d).

In the second structure, the first structure Representing the initial frequency, center frequency or end frequency of each first subband signal in set 1,representing the initial frequency of each first subband signal in set 2,Center frequency or termination frequency. Fig. 6a to 9d are each exemplified by an initial frequency.

In the third structure, the N first subband signals are prime I-type.

In one possible implementation, the first frequency interval ratio between any two first sub-band signals of the N first sub-band signals other than the reference band signal and the reference band signal satisfies the prime ratio. The reference frequency band signal is the first sub-band signal with the lowest frequency in the N first sub-band signals.

Taking any two first sub-band signals of the N first sub-band signals as an example, i.e. taking the ith first sub-band signal and the jth first sub-band signal as examples, the first frequency interval between the ith first sub-band signal and the reference frequency band signal is equal to N of the reference frequency step delta f _i The first frequency interval between the jth first sub-band signal and the reference band signal is equal to n of the reference frequency step amount _j Multiple, n _i And n _j Mutually, i is more than 1 and less than or equal to N, j is more than 1 and less than or equal to N, and i is not equal to j. I.e. n _i ∈(1，2，3，5，7，11，13，17，19，23，29，31，37，….)，n _j E (1, 2,3,5,7, 11, 13, 17, 19, 23, 29, 31, 37, …). It should be appreciated that the first frequency interval between the i-th first sub-band signal and the reference band signal may also be referred to as the offset of the i-th first sub-band signal. The first frequency interval between the jth first sub-band signal and the reference band signal may also be referred to as an offset of the jth first sub-band signal. Wherein the reference frequency step amount Δf is the minimum frequency interval corresponding to the maximum non-blurring distance, if the maximum non-blurring distance is r _max Then Δf=c/2 r _max 。

Fig. 10a is a schematic diagram of a time division mode distribution of N first subband signals provided in the present application. This example takes the frequency step signal as an example. The reference frequency band signal is the first sub-band signal f1 with the lowest frequency, and the first frequency interval between the first sub-band signal f2 and the reference frequency band signal f1 is equal to n of the reference frequency step amount deltaf ₂ The number of times of the number of times,the first frequency interval between the first sub-band signal f3 and the reference band signal f1 is equal to n of the reference frequency step amount Δf ₃ Times, and so on, the first subband signal f _N The first frequency interval from the reference band signal f1 is equal to n of the reference frequency step amount deltaf _N Multiple, n ₂ And n ₃ Mutual mass, n _N And n ₃ Mutual mass, n _N And n ₂ Mutually good quality.

As shown in fig. 10b, another distribution diagram of the time division modes of the N first subband signals provided in the present application is shown. This example takes the frequency modulated step signal as an example. The reference frequency band signal is the first sub-band signal f1 with the lowest frequency, and the first frequency interval between the first sub-band signal f2 and the reference frequency band signal f1 is equal to n of the reference frequency step amount deltaf ₂ The first frequency interval between the first sub-band signal f3 and the reference band signal f1 is equal to n of the reference frequency step amount Δf ₃ Times, and so on, the first subband signal f _N The first frequency interval from the reference band signal f1 is equal to n of the reference frequency step amount deltaf _N Multiple, n ₂ And n ₃ Mutual mass, n _N And n ₃ Mutual mass, n _N And n ₂ Mutually good quality.

As shown in fig. 10c, a distribution diagram of frequency division modes of N first subband signals is provided. This example takes the frequency step signal as an example. The reference frequency band signal is the first sub-band signal f1 with the lowest frequency, and the first frequency interval between the first sub-band signal f2 and the reference frequency band signal f1 is equal to n of the reference frequency step amount deltaf ₂ The first frequency interval between the first sub-band signal f3 and the reference band signal f1 is equal to n of the reference frequency step amount Δf ₃ Doubling the first subband signal f _N The first frequency interval from the reference band signal f1 is equal to n of the reference frequency step amount deltaf _N Multiple of n ₂ And n ₃ Mutual mass, n _N And n ₃ Mutual mass, n _N And n ₂ Mutually good quality.

As shown in fig. 10d, another distribution diagram of the frequency division modes of the N first subband signals provided in the present application is shown. In this example a frequency modulated step signal is taken as an example. The first frequency interval ratio between any two first sub-band signals except the reference band signal and the reference band signal in the N first sub-band signals satisfies the prime ratio, and the description of fig. 10b is specifically referred to and will not be repeated here.

Note that, the frequency steps shown in fig. 10a and 10c are non-uniform steps, and the frequency modulation steps shown in fig. 10b and 10d are also non-uniform steps. In addition, f1, f2 … f _N The initial frequency, the center frequency, or the end frequency of each first sub-band signal may be represented, and the above-described fig. 10a, 10b, 10c, and 10d are each exemplified by representing the initial frequency of the first sub-band signal.

When the N first sub-band signals satisfy the third structure, the reduction of the maximum distance ambiguity (the maximum unblurred distance is c/2 Δf) due to the excessively large first band interval between the adjacent two first sub-bands can be eliminated, and a larger equivalent bandwidth (i.e., (N-1) ×Δf) can be obtained. The following is a detailed description of the beneficial effects, in conjunction with the formulas.

The distance guide vector can be found in the following equation 3.

Wherein r is _m Representing the range of the mth target from the radar. When distance ambiguity occurs, i.e. r 'is present' _m So that alpha (r _m )＝α(r′ _m ) See equation 4 below.

By simplifying the above equation 4, the following equation 5 can be obtained.

Further simplifying the above equation 5, the following equation 6 can be obtained.

Is provided withThe following equation 7 can be obtained by substituting the above equation 6 for the maximum unblurred distance.

Due toThus, k _i ＜n _i ，

When n is _i When being mutually prime, ρ= { ρ ₂ ∩ρ ₃ ∩ρ _N = {0}, i.e. r _i ＝r′ _i 。

Based on the above derivation, it can be seen that when the first frequency interval between the first sub-band signal and the reference band signal is greater than the reference frequency step amount Δf, peaks are generated at other distances in addition to the peaks generated at the true distances, and these positions may be referred to as blur distances. Different firstThe positions of the generated fuzzy distances are different at a frequency interval, and further, the distance estimation results corresponding to all the first sub-band signals are intersected, because of n _i And n _j And the positions of the fuzzy distances corresponding to the first sub-band signals are different from each other, and all fuzzy distances after intersection are solved are not existed, so that only the true distance is left. In other words, when the N first sub-band signals satisfy the structure three, no additional distance ambiguity is generated.

Based on the possible sparse structures of the three N first sub-band signals, the problems of fuzzy distance, increased side lobe and the like existing when the large-broadband receiving and transmitting are obtained by using a limited number of narrowband signals can be solved. That is, by setting the sparse N first subband signals having a certain characteristic, the maximum unblurred distance can be kept unchanged, and a large bandwidth can be obtained. It will be appreciated that sparse bands may result in increased side lobes.

In one possible implementation, the transmitting module may be configured to transmit the first signal to the detection region. Further optionally, the transmit module may include a waveform generator (waveform generation) and a transmit antenna (transmit antenna).

For example, the waveform generator may generate a first signal of increasing first sub-band over time, which may be a frequency modulated continuous wave, or may also be a continuous wave or pulse. The transmit antenna may be used to transmit the first signal.

Further alternatively, if the detection system comprises a single transmitting antenna, the single transmitting antenna may transmit N first sub-band signals at different times. If the detection system includes a plurality of transmitting antennas, when the number of the transmitting antennas is greater than or equal to N, the plurality of transmitting antennas may transmit N first subband signals at the same time; when the number of the transmitting antennas is less than N and greater than 1, part of the transmitting antennas may transmit the first subband signals at different times, and part of the transmitting antennas may transmit the first subband signals at the same time.

It should be noted that, the transmitting module typically performs the first signal transmission of multiple sweep periods in a continuous period. The frequency sweep period refers to a period of transmitting a first signal with a complete waveform, that is, transmitting N first subband signals may be a frequency sweep period, and a distance information of the target may be obtained based on the first signal with a complete waveform.

2. Receiving module

In one possible implementation, the receiving module may include a receiving antenna, a mixer, a filter, and an analog-to-digital converter (ADC), see fig. 11. The receiving antenna is used for receiving echo signals transmitted by a target, the mixer is used for mixing the echo signals received by the receiving antenna with local oscillation signals to obtain intermediate frequency signals, the intermediate frequency signals pass through the low-pass filter to obtain low-frequency signals, and the ADC is used for converting the low-frequency analog signals into digital signals so as to enter the processing module for subsequent processing.

3. Processing module

In one possible implementation, the echo signal may be a coherent superposition that is seen as a limited number of strongly scattering centers. For broadband signals in the optical region (i.e., the target size is much larger than the signal wavelength), the geometric diffraction theory (geometric theory of diffraction, GTD) scattering center model of the target's back-scattered electric field (i.e., the electric field of the echo signal) can be expressed by the following equation 8:

wherein M represents the number of scattering centers, A _m Represents the scattering intensity of the mth scattering center, r _m Represents the position of the mth scattering center, f _n ＝f ₀ +Δf _n ，f ₀ For the initial frequency (i.e. the initial frequency of the reference band), Δf _n For the frequency value f _n The frequency difference from the initial frequency, c is the propagation velocity of the electromagnetic wave, c=3×10 ⁸ m/s。α _m Representing the type of scattering corresponding to the mth scattering center, which may be referred to as the scattering center geometry, for different targetsStructure alpha _m Selecting different values (i.e. alpha _m Related to the geometry of the target).

As can be seen from equation 8 above, the first three termsIs a frequency independent amplitude term; fourth directionA phase difference introduced for the frequency difference, for determining (or referred to as estimating) distance information of the target; last itemThe term of frequency error introduced for the scattering properties of the object affects the distance information of the object to be determined, so that the last term needs to be preprocessed (otherwise called compensation or correction) when determining the distance information of the object.

It will be appreciated that the last term in equation 8 above is negligible when the frequency separation between any adjacent two of the N first sub-band signals is less than the frequency threshold. When the frequency interval between at least two first sub-band signals among the N second sub-band signals is greater than the frequency threshold, the last term in the above equation 8 cannot be ignored. Therefore, the processing module may perform frequency compensation on the N second subband signals before performing the synthesis processing on the N second subband signals, so as to achieve that the N second subband signals are consistent with the target scattering characteristic.

It should be noted that, after one first subband signal is reflected by the target, one second subband signal is obtained, in other words, N first subband signals are in one-to-one correspondence with N second subband information.

As can be seen from the above equation 8, the error term to be compensated mainly depends on the target scattering center geometry factor (or scattering coefficient) α _m . In a kind ofIn a possible implementation manner, the processing module may be configured to determine a scattering center geometry factor of the target from the echo signalFurther, it can be based on scattering center geometry factorsAnd performing frequency compensation on the received N second sub-band signals.

An exemplary illustration of a geometric factor α for the scattering center of the target is shown below _m Is a way of estimating.

Selecting N 'second sub-bands of the N second sub-bands, assuming that the initial frequency of the second sub-bands is f' ₀ These second sub-bands satisfy: each of the selected N 'second sub-bands is related to f' ₀ Frequency offset from f' ₀ The ratio of (2) is much smaller than 1. Taking N' second subbands as an example of uniform stepping, i.e. f=f ₀ +kΔf, at this time, there are:

wherein,

p is found according to equation 9 _m Alpha can be obtained _m Is used for the estimation of the estimated value of (a). According to formula 9,P _m Can be converted into classical spatial spectrumThe estimation problem can be estimated by using classical spectrum estimation algorithms such as MUSIC algorithm, rotation invariant subspace (ESPRIT) algorithm and the like. Taking the ESPRIT algorithm as an example, one possible estimate α _m The process is as follows:

step 11, reconstructing a Hankel matrix X according to the scattered echo data, and calculating a covariance matrix R of the Hankel matrix X;

step 12, the covariance matrix R is subjected to eigenvalue decomposition to obtain a signal subspace U _s U is set up _s The last line is removed to obtain U _s1 U is set up _s First line is removed to obtain U _s2 ；

Step 13, calculatingObtaining P _m ＝eig(ψ)；

Step 14, according to P _m Can obtain alpha from the amplitude information of (a) _m Is used for the estimation of the estimated value of (a). .

Taking the nth second sub-band signal as an example, the compensation factor of the nth second sub-band signal can be determinedThe nth second subband signal multiplied by a compensation factorThe last term in equation 8 is eliminated to obtain the n-th second subband signal after the supplement, as shown in equation 10 below.

Based on the above-mentioned compensated formula 10, the inconsistency of the scattering characteristics of the target due to the difference in frequency between different sub-band signals is compensated, and the distance information of the target can be further estimated subsequently by using the compensated sub-band signals.

And combining the three possible structures respectively, and carrying out aggregation processing on the N second sub-band signals subjected to frequency consistency compensation, so that equivalent large-bandwidth distance information can be obtained.

Based on the first structure

In one possible implementation, the processing module may be further configured to perform and/or differential processing on the compensated N second subband signals to obtain P virtual subband signals, where P is an integer greater than N. Further optionally, the processing module may determine the distance information of the target according to the P virtual subband signals. Wherein the P virtual subband signals may be continuous and frequency stepped uniform virtual subband signals. Based on the first structure, a continuous and uniform virtual sub-band signal can be obtained through the sum/difference processing, and the continuous and uniform (namely, the virtual sub-band signal can be regarded as non-sparse) is utilized for distance estimation, so that the effects of unchanged maximum non-fuzzy distance, increased degree of freedom and reduced side lobe can be achieved.

When h=2, the P virtual subband signals include virtual subband signals equal to j times the reference frequency step amount, where j takes { -N ₂ (N ₁ +1)-1,….,N ₂ (N ₁ +1) -1 }. It is also understood that the P virtual subband signals constitute a virtual subband set comprising a number of virtual subbands of 2N ₂ (N ₁ +1) -1, i.e. j x Δf for each virtual subband signal, j takes { -N ₂ (N ₁ +1)-1,….,N ₂ (N ₁ +1) -1 }. That is, the compensated N second sub-band signals can obtain 2N ₂ (N ₁ +1) -1 degrees of freedom. In other words, if the N first subband signals are sparse based on the first structure, the processing module may estimate the distance information for a greater number of targets.

In combination with FIG. 4a, described above, N ₁ ＝N ₂ For example, =3, n=6, i.e. the echo signal comprises 6 second subband signals. The processing module may be configured to perform sum/difference processing on the received compensated 6 second subband signals to obtain 23 uniformly distributed virtual subband signals, which may be seen in fig. 12. These 23 virtual subband signals may constitute a set of virtual frequency signals, i.e., { -11, -10, -9, -8, -7, -6, -5, -4, -3, -2, -1,0,1,2,3,4,5,6,7,8,9, 10, 11}. It should be understood that the weights for each virtual subband signal are also included in fig. 12. The weight corresponding to each virtual subband signal represents the number of times the 6 second subband signals are subjected to sum/difference processing to obtain the virtual subband signal. For example, f ₀ Is of weight 6, means that the processing module performs sum/difference processing on the 6 second echo signals, f ₀ 6 occurrences were made. Further optionally, the processing module may determine the distance information of the target according to the 23 virtual subband signals obtained above.

Illustratively, the processing module may obtain the virtual subband signals by vectorizing the covariance matrix of the echo signals, and then perform distance estimation on the obtained virtual subband signals by using a smooth multiple signal classification (multiple signal classification, MUSIC) algorithm, which specifically includes the following processing procedures:

step 21, calculating covariance matrix R of echo signals (including compensated N second sub-band signals) (for the linear frequency modulation signal, pulse compression is needed first, peak signal after pulse compression is taken) _XX Vector z is obtained by vectorization processing, and the virtual sub-band signal zz is obtained by sequencing z and deleting redundancy (or performing redundancy average);

step 22, obtaining the covariance matrix R of zz by spatial smoothing _zz And writing a guide vector a (r);

step 23, utilizing R _zz Performing eigenvalue decomposition to obtain a noise subspace U _N ；

Step 24, constructing MUSIC spectrumAnd traversing different distance values, and searching through spectrum peaks to obtain the distance information of the target.

Based on the second structure

In one possible implementation, the processing module may be further configured to perform sum/difference processing on the compensated N second subband signals to obtain Q virtual subband signals, where Q is an integer greater than N.

Further, distance information of the target may be determined from the Q virtual subband signals. Where there may be virtual subband signals that are partially continuous and frequency stepped uniformly in the Q virtual subband signals.

In combination with FIG. 6a, described above, N ₁ ＝4，N ₂ For example, =3, n=7, i.e. the echo signal comprises 7 compensated second subband signals. The processing module may be configured to perform sum/difference processing on the received compensated 7 second subband signals to obtain 17 virtual subband signals, which may refer to fig. 13. These 17 virtual subband signals may constitute a set of virtual frequency signals, i.e., { -9, -8, -6, -5, -4, -3, -2, -1,0,1,2,3,4,5,6,8,9}, wherein 13 elements between-6 are continuously and evenly distributed.

Further, a continuous and evenly distributed portion of the virtual frequency signal set (i.e., { -6, -5, -4, -3, -2, -1,0,1,2,3,4,5,6 }) may be selected to determine the range information of the target. It may be also understood that, in the case where the sum/difference processing is performed on the compensated N second subband signals to obtain the virtual subband signal set including the fact that the virtual subband signal set is not completely uniform and continuous, the distance information of the target may be performed by selecting a continuous and uniformly distributed portion around the 0 value in the virtual subband signal set. Thus, the maximum non-blurring distance is unchanged, and the sidelobe is reduced. Further, the degree of freedom increases. Illustratively, the processing module may determine the range information of the target based on 13 consecutive uniformly distributed virtual sub-band signals between-6 and 6.

Based on the second structure, the processing module may obtain a virtual frequency band signal by vectorizing a covariance matrix of the received signal, then select a continuous and uniform stepping portion of the virtual frequency band signal, and perform distance estimation by using a smoothing MUSIC algorithm. The specific process flow may refer to the above determination process based on the structure one, and will not be described herein.

Based on the third structure

In one possible implementation, the processing module may determine the distance information of the target using the N second subband signals after frequency compensation using a MUSIC algorithm.

Specifically: the processing module can determine a covariance matrix Rxx of the echo signals, and perform eigenvalue decomposition by using the covariance matrix Rxx to obtain a noise subspace U _N The method comprises the steps of carrying out a first treatment on the surface of the Reconstruction structureThe distance estimation is obtained by one-dimensional spectral peak search. Wherein the steering vector a (r) is determined by N sub-bands of structure three having a mutual quality relationship,

illustratively, the processing module may be a processor, which may be a central processing unit (central processing unit, CPU), other general purpose processor, digital signal processor (digital signal processor, DSP), application specific integrated circuit (application specific integrated circuit, ASIC), field programmable gate array (field programmable gate array, FPGA) or other programmable logic device, transistor logic device, hardware components, or any combination thereof. The general purpose processor may be a microprocessor, but in the alternative, it may be any conventional processor.

In another embodiment provided herein, a detection system may include a transmitting module that may be configured to transmit N first sub-band signals, which may be three possible configurations as exemplified above. That is, the transmitting module in the detection system is configured to transmit N first sub-band signals, and a frequency interval between the N first sub-band signals is not limited, that is, a frequency interval between any two first sub-band signals in the N first sub-band signals may be not greater than a frequency threshold or may be greater than a frequency threshold, which is not limited.

Based on the detection system, if a frequency interval between any two first sub-band signals in the N first sub-band signals is not greater than a frequency threshold; accordingly, the processing module does not need to compensate the N second subband signals, and further, the distance information of the target can be determined based on the N second subband signals that do not need to be compensated.

Based on the detection system, if a frequency interval between any two first sub-band signals in the N first sub-band signals is greater than a frequency threshold; the processing procedure of the processing module can be referred to the related description, and will not be repeated here.

Based on the structural and functional principles of the detection system described above, the present application may also provide a terminal device, which may include the detection system of any of the embodiments described above. Further optionally, the terminal device may further include a path planning module, where the path planning module may be configured to plan a travel path of the terminal device according to the determined distance information of the target. For example, avoid obstacles on the travel path, etc. Of course, the terminal device may also comprise other means, such as a memory and wireless communication means, etc.

The detection system may be, for example, a terminal device, such as a radar, a smart phone, a smart home device, a smart manufacturing device, a robot, an unmanned aerial vehicle, or a smart transport device (e.g., an automated guided transport vehicle (automated guided vehicle, AGV), or an unmanned transport vehicle, etc.), etc.

Based on the foregoing and the same, the present application provides a detection method, please refer to the description of fig. 14. The detection method can be applied to the detection system shown in any of the embodiments of fig. 3 to 13 described above. It will also be appreciated that the detection method may be implemented based on the detection system described above in any of the embodiments of fig. 3-13.

The detection method comprises the following steps:

in step 1401, an echo signal is received.

The echo signal comprises N second sub-band signals, the echo signal is a signal which is received by the radar after being reflected by the first signal, the first signal comprises N first sub-band signals, and the frequency interval between at least two first sub-band signals in the N first sub-band signals is larger than a frequency threshold value.

This step 1401 may be performed by the above-mentioned receiving module, and may be specifically referred to the description of the function of the above-mentioned receiving module, and the description of the function of the above-mentioned transmitting module may be referred to the first echo signal, which is not repeated here.

Step 1402, determining a scattering center geometry factor of the target from the echo signals.

In one possible implementation, the scattering center geometry factor α may be determined based on a GTD scattering center model _m See the above description for details, and are not repeated here.

Step 1403, frequency compensating the N second subband signals according to the scattering center geometry factor.

In one possible implementation, the nth second subband signal may be multiplied by a compensation factorWherein n is an integer greater than 1,the nth second sub-band signal is any one of the N second sub-band signals, and the delta f is the scattering center geometric factor of the target _n An initial frequency f for the nth second sub-band signal and the lowest frequency second sub-band signal ₀ Frequency spacing between.

In step 1404, distance information of the target is determined according to the compensated N second subband signals.

If the N first subband signals are based on the first structure, the compensated N second subband signals may be subjected to sum/difference processing to obtain P virtual subband signals, where the P virtual subband signals may be continuous virtual subband signals with uniform frequency steps, and further, distance information of the target may be determined according to the P virtual subband signals, where P is an integer greater than N.

If the N first subband signals are based on the second structure, performing sum/difference processing on the compensated N second subband signals to obtain Q virtual subband signals, where a part of the Q virtual subband signals may have virtual subband signals with continuous and uniform frequency steps; further, a continuous and frequency-stepped uniform virtual sub-band signal, and determining distance information of the target according to the selected continuous and uniform virtual sub-band signal, wherein Q is an integer greater than N.

It should be noted that, all of the steps 1401 to 1404 may be performed by the processing module.

The detection method can be applied to the Internet of vehicles, such as vehicle external connection (vehicle to everything, V2X), long-term evolution technology (long term evolution-vehicle, LTE-V), vehicle-vehicle (vehicle to everything, V2V) and the like.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are performed in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, a network device, a user device, or other programmable apparatus. The computer program or instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer program or instructions may be transmitted from one website site, computer, server, or data center to another website site, computer, server, or data center by wired or wireless means. The computer readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that integrates one or more available media. The usable medium may be a magnetic medium, e.g., floppy disk, hard disk, tape; optical media, such as digital video discs (digital video disc, DVD); but also semiconductor media such as solid state disks (solid state drive, SSD).

In the various embodiments of the application, if there is no specific description or logical conflict, terms and/or descriptions between the various embodiments are consistent and may reference each other, and features of the various embodiments may be combined to form new embodiments according to their inherent logical relationships.

In this application, "uniform" does not mean absolutely uniform, and may allow for some engineering error. "and/or", describe the association relationship of the associated objects, and the representation may have three relationships, for example, a and/or B may represent: a alone, a and B together, and B alone, wherein a, B may be singular or plural. In the text description of the present application, the character "/", generally indicates that the associated object is an or relationship. In the formulas of the present application, the character "/" indicates that the front and rear associated objects are a "division" relationship. In addition, in this application, the term "exemplary" is used to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. It is to be understood that the use of the term "exemplary" is intended to present concepts in a concrete fashion and is not intended to be limiting.

It will be appreciated that the various numerical numbers referred to in this application are merely descriptive convenience and are not intended to limit the scope of embodiments of this application. The sequence number of each process does not mean the sequence of the execution sequence, and the execution sequence of each process should be determined according to the function and the internal logic. The terms "first," "second," and the like, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion, such as a series of steps or elements. The method, system, article, or apparatus is not necessarily limited to those explicitly listed but may include other steps or elements not explicitly listed or inherent to such process, method, article, or apparatus.

Although the present application has been described in connection with specific features and embodiments thereof, it will be apparent that various modifications and combinations can be made without departing from the spirit and scope of the application. Accordingly, the specification and drawings are merely exemplary of the arrangements defined in the appended claims and are to be construed as covering any and all modifications, variations, combinations, or equivalents that are within the scope of the application.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the invention. Thus, if such modifications and variations of the embodiments of the present application fall within the scope of the claims and the equivalents thereof, the present application is intended to encompass such modifications and variations.

Claims

A detection system, comprising:

a transmitting module, configured to transmit a first signal, where the first signal includes N first subband signals, and a frequency interval between at least two first subband signals in the N first subband signals is greater than a frequency threshold;

the receiving module is used for receiving echo signals, the echo signals comprise N second sub-band signals, and the echo signals are signals received by the detection system after the first signals are reflected by the target;

the processing module is used for determining a scattering center geometric factor of the target according to the echo signal, carrying out frequency compensation on the N second sub-band signals according to the scattering center geometric factor, and determining distance information of the target according to the N compensated second sub-band signals.
The system according to claim 1, wherein the processing module is specifically configured to:

Multiplying the nth second subband signal by a compensation factor

Wherein n is an integer greater than 1,the nth second sub-band signal is any one of the N second sub-band signals, and the delta f is the scattering center geometric factor of the target _n An initial frequency f for the nth second sub-band signal and the lowest frequency second sub-band signal ₀ Frequency spacing between.
The system of claim 1 or 2, wherein any two first frequency interval ratios satisfy a prime ratio, the first frequency interval being a frequency interval between the first sub-band signal and the reference band signal;

the reference frequency band signal is the first frequency sub-band signal with the lowest frequency in the N first frequency sub-band signals.
The system of claim 3, wherein a frequency separation between an ith first sub-band signal and the reference band signal is equal to n of a reference frequency step amount _i The ith first sub-band signal is one of the N first sub-band signals;

wherein the reference frequency step amount is inversely proportional to the maximum non-ambiguity distance.
The system of claim 1 or 2, wherein the N first subband signals correspond to H sets, the sets comprising at least two first subband signals, the H being an integer greater than 1;

Wherein the third frequency interval is equal to (N of the second frequency interval _k +1) the third frequency interval is the frequency interval between any two adjacent first sub-band signals in the kth+1th set, the second frequency interval is the frequency interval between any two adjacent first sub-band signals in the kth set, the N _k Is the number of first subbands included in the kth set.
The system of claim 5, wherein the processing module is specifically configured to:

performing sum/difference processing on the compensated N second sub-band signals to obtain P virtual sub-band signals, wherein P is an integer greater than N;

and determining the distance information of the target according to the P virtual sub-band signals.
The system of claim 6, wherein when H = 2, k = 1;

wherein the N is ₁ For the number of first subband signals comprised by the first set, said N ₂ For the number of first subband signals comprised by the second set.
The system of claim 7, wherein the P virtual sub-band signals comprise virtual sub-bandsThe pseudo-subband signal is j times the reference frequency step amount, and j is { -N ₂ (N ₁ +1)-1,….,N ₂ (N ₁ +1) -1 }.
The system of claim 1 or 2, wherein the N first subband signals correspond to M sets, the sets comprising at least two first subband signals, the M being an integer greater than 1;

the mth set includes N _m A first subband signal, an m+1th set including N _m+1 A first sub-band signal, N _m+1 And said AND N _m The mth set and the (m+1) th set are two sets in the M sets;

the fourth frequency interval is equal to N of the reference frequency step amount _m+1 The fourth frequency interval is the frequency interval between any two adjacent first sub-band signals in the m-th set; the reference frequency step amount is inversely proportional to the maximum non-blurring distance, and p is a positive integer;

the fifth frequency interval is equal to N of the reference frequency step amount _m The fifth frequency interval is the frequency interval between any two adjacent first sub-band signals in the (m+1) th set.
The system of claim 9, wherein an initial frequency of the lowest frequency first subband signal in the mth set coincides with an initial frequency of the lowest frequency first subband signal in the m+1th set.
The system of claim 9, wherein the mth set and the m+1th set are any adjacent two sets of M sets, a frequency separation between a first sub-band signal of a highest frequency in the mth set and a first sub-band signal of a lowest frequency in the m+1th set is equal to L times the reference frequency step amount, and L is a positive integer.
The system of claim 11, wherein L is the N _m And said N _m+1 Is the minimum value of (a).
The system according to any of the claims 9 to 12, wherein the processing module is specifically configured to:

performing sum/difference processing on the compensated N second sub-band signals to obtain Q virtual sub-band signals, wherein Q is an integer greater than N;

and determining the distance information of the target according to the Q virtual sub-band signals.
The system of any of claims 1 to 13, wherein the transmit module is a single transmit antenna;

the transmitting module is specifically configured to:

the N first subband signals are transmitted at different times.
The system of any one of claims 1 to 13, wherein the transmitting module is a plurality of transmitting antennas;

The transmitting module is specifically configured to:

transmitting the N first sub-band signals at the same time; or,

the N first subband signals are transmitted at different times.
A terminal device comprising a detection system according to any one of claims 1 to 15, and a processor for processing the distance information determined by the detection system.
A method of detection, comprising:

receiving an echo signal; the echo signals comprise N second sub-band signals, the echo signals are signals received by the radar after the first signals are reflected by the targets, the first signals comprise N first sub-band signals, and the frequency interval between at least two first sub-band signals in the N first sub-band signals is larger than a frequency threshold;

determining a scattering center geometric factor of the target according to the echo signal;

performing frequency compensation on the N second sub-band signals according to the scattering center geometric factors;

and determining the distance information of the target according to the N compensated second sub-band signals.
The method of claim 17, wherein said frequency compensating said N second subband signals according to said scattering center geometry comprises:

Multiplying the nth second subband signal by a compensation factor

Wherein n is an integer greater than 1,the nth second sub-band signal is any one of the N second sub-band signals, and the delta f is the scattering center geometric factor of the target _n An initial frequency f for the nth second sub-band signal and the lowest frequency second sub-band signal ₀ Frequency spacing between.
The method of claim 17 or 18, wherein any two first frequency interval ratios satisfy a prime ratio, the first frequency interval being a frequency interval between the first sub-band signal and the reference band signal;

the reference frequency band signal is the first frequency sub-band signal with the lowest frequency in the N first frequency sub-band signals.
The method of claim 17 or 18, wherein the N first subband signals correspond to H sets, the sets comprising at least two first subband signals, the H being an integer greater than 1;

wherein the third frequency interval is equal to (N of the second frequency interval _k +1) the third frequency interval is the frequency interval between any two adjacent first sub-band signals in the kth+1th set, the second frequency interval is the frequency interval between any two adjacent first sub-band signals in the kth set, the N _k Is the number of first subbands included in the kth set.
The method of claim 17 or 18, wherein the N first subband signals correspond to M sets, the sets comprising at least two first subband signals, the M being an integer greater than 1;

the mth set includes N _m A first subband signal, an m+1th set including N _m+1 A first sub-band signal, N _m+1 And said AND N _m The mth set and the (m+1) th set are two sets in the M sets;

the fourth frequency interval is equal to N of the reference frequency step amount _m+1 The fourth frequency interval is the frequency interval between any two adjacent first sub-band signals in the m-th set; the reference frequency step amount is inversely proportional to the maximum non-blurring distance, and p is a positive integer;

the fifth frequency interval is equal to N of the reference frequency step amount _m The fifth frequency interval is the frequency interval between any two adjacent first sub-band signals in the (m+1) th set.
The method according to claim 20 or 21, wherein said determining distance information of the target from the compensated N second sub-band signals comprises:

Performing sum/difference processing on the compensated N second sub-band signals to obtain H virtual sub-band signals, wherein H is an integer greater than N;

and determining the distance information of the target according to the H virtual sub-band signals.
The method of claim 22, wherein the performing and/or differentiating the compensated N second subband signals comprises:

vectorizing covariance matrixes of the N compensated second sub-band signals;

the determining the distance information of the target according to the H virtual sub-band signals includes:

and processing the H virtual sub-band signals by adopting a smooth multiple signal classification MUSIC algorithm to obtain the distance information of the target.
The method of any one of claims 17 to 23, wherein the method further comprises:

transmitting the N first subband signals at different times; or,

the N first sub-band signals are transmitted at the same time instant.
A computer readable storage medium comprising computer instructions which, when executed, cause the detection system to perform the method of any of claims 17 to 24.