CN116819509B - Radar positioning and ranging method based on spread spectrum time domain reflection - Google Patents
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Abstract
The invention discloses a radar positioning and ranging method based on spread spectrum time domain reflection, and relates to the technical field of radar positioning and ranging. In the method, sample data are obtained by respectively calculating and sampling the autocorrelation signals of the spread spectrum detection signal and the autocorrelation signals of the reflection signal, a cost function of the autocorrelation signals is constructed, a plurality of iterative operations are carried out, a fitting vector for minimizing the cost function is solved by adopting a rapid gradient descent method, and the delay time of the autocorrelation signals of the spread spectrum detection signal and the autocorrelation signals of the reflection signal is obtained，Thereby calculating the radar ranging size. The invention improves the radar positioning and ranging precision and enhances the reliability of radar positioning and ranging.
Description
Technical Field
The invention relates to the field of radar positioning and ranging, in particular to a radar positioning and ranging method based on spread spectrum time domain reflection.
Background
Radar is a technology for detecting and ranging by electromagnetic waves, and is widely applied to the fields of aviation, navigation, automobile traffic, weather forecast, unmanned aerial vehicles and the like. The radar is used on aircrafts and ships, can detect targets and provide information, supports flying and navigation decisions, can improve the safety and efficiency of aircrafts and ships, and reduces the occurrence of collision accidents. The radar is used in the fields of automobiles and traffic, can be used for enhancing the visual field of drivers and improving the driving safety performance, and can realize automatic driving, collision prevention, braking and the like, thereby reducing traffic accidents. The radar is used in the unmanned aerial vehicle field, and can realize functions such as navigation, obstacle avoidance, detection and the like.
The positioning and ranging function of the radar is a core function of the radar, and the function is realized by calculating the time delay between the detection signal and the reflected signal to realize the positioning and ranging of the radar. Therefore, measuring the time delay between the probe signal and the reflected signal is critical to radar location ranging accuracy. In the prior art, the time delay is usually calculated by directly comparing peak points of the detection signal and the reflection signal; however, the method is easily affected by factors such as waveform distortion, sampling clock jitter, channel interference and the like, so that the compared peak point is not a real peak point, delay measurement errors are easily caused, and thus, radar positioning and ranging errors are caused. Further, in the prior art, the basic waveforms of the detection signals transmitted by the radar positioning and ranging have continuous waves and pulse modulation waves. The continuous wave is transmitted by a waveform which is continuous in time, and the transmission and the reception of the waveform need to adopt independent receiving antennas and independent transmitting antennas; the pulse modulation wave is composed of intermittent pulse signals in time, the pulse duration is between tens nanoseconds and hundreds microseconds, the pulse repetition frequency is between hundreds hertz and 1MHz, and the same antenna can be used for receiving and transmitting. However, the anti-interference capability of the waveform of the existing radar detection signal is weak, and the existing radar detection signal is difficult to adapt to complex electromagnetic environments, especially along with the development of radar theory and technology and the increasing complexity of the condition of the modern electromagnetic environment, the existing system radar detection signal is easy to interfere and intercept, so that the detection signal is easy to distort, the true peak points of the detection signal and the reflected signal are difficult to capture, the positioning range error is increased, and the modern application requirements are difficult to meet.
Therefore, how to improve the positioning and ranging precision of the radar and enhance the anti-interference capability of the detection waveform is a difficult problem to be solved in the radar field.
Disclosure of Invention
The invention aims to: in order to overcome the defects in the prior art, the invention provides a radar positioning ranging method based on spread spectrum time domain reflection, so as to improve the radar positioning ranging precision and enhance the reliability of radar positioning ranging.
The technical scheme is as follows: in order to achieve the above object, the radar positioning ranging method based on spread spectrum time domain reflection of the present invention comprises:
step one: transmitting a spread spectrum detection signal and waiting for receiving a reflected signal;
step two: respectively calculating an autocorrelation signal of the spread spectrum detection signal and an autocorrelation signal of the reflection signal;
step three: sampling the autocorrelation signal of the spread spectrum detection signal to obtain sample data of the autocorrelation signal of the spread spectrum detection signal, and recording the sample data as sample data [ X, Y ]]={(x 1 ，y 1 )，(x 2 ，y 2 )，…，(x i ，y i )，…，(x N ，y N ) And } wherein,x i 、y i the first of the autocorrelation signals respectively representing the spread spectrum detection signalsiSample time point and the firstiThe magnitude of the amplitude value is calculated,Nrepresenting the number of sampling time points; sampling the autocorrelation signal of the reflected signal to obtain sample data of the autocorrelation signal of the reflected signal, denoted as sample data [ P, Q ]]={(p 1 ，q 1 )，(p 2 ，q 2 )，…，(p i ，q i )，…，(p N ，q N ) And } wherein,p i 、q i the first of the autocorrelation signals respectively representing the reflected signalsiSample time point and the firstiThe magnitude of the amplitude value is calculated,Nrepresenting the number of sampling time points;
step four: calculating a cost function J (θ) of an autocorrelation signal of the spread spectrum detection signal:
，
wherein,is a fitting function and->，MRepresents the number of sample data, θ is the fitting vector and θ= (θ) 0 ，θ 1 ，θ 2 )，θ 0 、θ 1 、θ 2 A first element, a second element and a third element respectively representing a fitting vector θ; solving for θ when minimizing cost function J (θ) 0 、θ 1 、θ 2 Is a value of (2);
calculating a cost function ψ (γ) of an autocorrelation signal of the reflected signal:
，
wherein,is a fitting function and->，MRepresents the number of sample data, γ represents the fitting vector and γ= (γ) 0 ，γ 1 ，γ 2 )，γ 0 、γ 1 、γ 2 The first element, the second element and the third element of the fitting vector gamma are respectively represented; solving for gamma when minimizing cost function ψ (gamma) 0 、γ 1 、γ 2 Is a value of (2);
step five: calculating a delay time of an autocorrelation signal of the spread spectrum detection signal and an autocorrelation signal of the reflected signalτThe delay timeτThe method comprises the following steps:
，
wherein θ 0 、θ 1 、θ 2 、γ 0 、γ 1 、γ 2 Solving the obtained value in the fourth step;
step six: calculating radar ranging sized，WhereinvIs the propagation velocity of electromagnetic waves.
Further, the method for solving the fitting vector θ when the cost function J (θ) is minimized is divided into the following steps:
step one: setting θ 0 、θ 1 、θ 2 Initial values of (1) are respectively recorded as、/>、/>；
Step two: from sample data [ X, Y]={(x 1 ，y 1 )，(x 2 ，y 2 )，…，(x i ，y i )，…，(x N ，y N ) Random decimation in }MThe sample data are grouped into a subset of sample data, whereinM＜N，
；
Step three: solving for、/>、/>Wherein, the method comprises the steps of, wherein,
，
，
；
wherein,；
step four: updating theta 0 、θ 1 、θ 2 Wherein, in the values of (c), wherein,
，
，
；
wherein,μis a gradient descent factor;
step five: will be theta 0 、θ 1 、θ 2 And substituting the value of (c) into J (θ), calculating and recording the value of J (θ), wherein,
；
step six: repeating the contents of the second to fifth steps, and taking the corresponding value of J (theta) when the execution times K are the smallestθ 0 、θ 1 、θ 2 The value of θ= (θ) as the fitting vector 0 ，θ 1 ，θ 2 ) Is a value of (2).
Further, the method for solving the fitting vector γ when the cost function ψ (γ) is minimized is divided into the following steps:
step one: setting gamma 0 、γ 1 、γ 2 Initial values of (1) are respectively recorded as、/>、/>；
Step two: from sample data [ P, Q]={(p 1 ，q 1 )，(p 2 ，q 2 )，…，(p i ，q i )，…，(p N ，q N ) Random decimation in }MThe sample data are grouped into a subset of sample data, whereinM＜N，
；
Step three: solving for、/>、/>The method comprises the steps of carrying out a first treatment on the surface of the Wherein,
，
，
；
wherein,；
step four: updatingγ 0 、γ 1 、γ 2 Wherein, in the values of (c), wherein,
，
，
；
wherein,μis a gradient descent factor;
step five: will beγ 0 、γ 1 、γ 2 Is substituted into the value of ψ (y), the value of ψ (y) is calculated and recorded, wherein,
；
step six: repeating the contents of the second to fifth steps, wherein the execution times K are the corresponding times when the value of ψ (gamma) is the minimumγ 0 、γ 1 、γ 2 The value of gamma= (gamma) as the fitting vector 0 ，γ 1 ，γ 2 ) Is a value of (2).
Further, at the firstkThe spread spectrum detection signal in the repetition period time is as follows:
，
wherein,c j for the number of chipsFPseudo-random sequence of (c)jThe amplitude of the individual chips is determined,γ(t) In order to shape the pulse(s),τ pulse for shaping the pulseγ(t) Is used for the time width of (a),f c for the carrier frequency of the spread spectrum probe signal,μfor the frequency modulation slope,φ k is the firstkInitial phase of each repetition period.
Preferably, the pulse waveformγ(t) Is cos 2 A bell-shaped pulse, said cos 2 The rise time of the bell-shaped pulse is:the fall time is: />。
Preferably, the execution number k=20.
Compared with the prior art, the invention has the following beneficial effects:
(1) The radar positioning and ranging precision is improved:
in the technical scheme disclosed by the invention, in order to reduce the capture difficulty of the peak value of the comparison signal and improve the accuracy of the comparison, the autocorrelation signals of the spread spectrum detection signal and the reflection signal are solved, then the autocorrelation signals are sampled to obtain sampled data, and the cost functions of the autocorrelation signals of the spread spectrum detection signal and the reflection signal are respectively constructed based on the sampled data; solving a fitting vector value for minimizing the cost function by adopting a rapid gradient descent method through repeated iterative operation; and finally, calculating the time delay and the positioning distance by using the fitting vector value of the spread spectrum detection signal and the fitting vector value of the reflection signal. According to the technical scheme disclosed by the invention, the peak points of the autocorrelation signals of the spread spectrum detection signals and the reflection signals can be accurately captured by adopting the data fitting and numerical calculation modes, and the peak points of the detection signals and the reflection signals are not directly compared to calculate the transmission delay so as to obtain the positioning distance; the technical scheme disclosed by the invention is less influenced by sampling clock jitter and waveform distortion. In the prior art, the positioning distance is usually obtained by directly comparing peak points of the detection signal and the reflection signal to calculate the transmission delay, and the prior art scheme is easily affected by factors such as waveform distortion, sampling clock jitter, channel interference and the like, so that the compared peak points are not real peak points, thereby causing delay measurement errors and causing radar positioning ranging errors. Compared with the prior art, the technical scheme disclosed by the invention improves the accuracy of radar positioning and ranging.
(2) The anti-interference capability of radar detection waveforms is enhanced:
in the prior art, the basic waveforms of detection signals emitted by radar positioning and ranging mainly adopt continuous waves and pulse modulation waves. Continuous wave emission is a waveform that is continuous in time; the pulse modulation wave is composed of intermittent pulse signals in time, and the pulse duration is between tens of nanoseconds and hundreds of microseconds; however, the anti-interference capability of the waveform of the existing radar detection signal is weak, and the existing radar detection signal is difficult to adapt to complex electromagnetic environments, especially along with the development of radar theory and technology and the increasing complexity of the condition of the modern electromagnetic environment, the existing system radar detection signal is easy to interfere and intercept, so that the detection signal is easy to distort, the true peak points of the detection signal and the reflected signal are difficult to capture, the positioning range error is increased, and the modern application requirements are difficult to meet.
In the technical proposal disclosed by the invention, the detection signal emitted by the radar is a broadband spread spectrum detection signal, and cos is adopted 2 The bell-shaped pulse is used as a forming pulse, so that the problem of poor energy aggregation of rectangular forming pulse is solved, the power efficiency of a detection signal is improved, and waveform distortion caused by band-pass devices such as antenna filtering is reduced; further, in order to improve the reliability of the detection signal in the channel transmission process, a pseudo-random sequence with good autocorrelation characteristics is adopted, so that the energy of the detection signal is expanded to a wider frequency spectrum range, and the concealment capability of the radar detection signal is improved; furthermore, the pseudo-random sequence enables the autocorrelation signals of the detection signal and the reflection signal to have sharp peak characteristics, so that the peak time point of the autocorrelation signals is easier to capture, the time delay of the detection signal and the reflection signal can be accurately calculated, and the radar positioning and ranging precision is improved. Compared with the prior art, the technical scheme disclosed by the invention ensures that the radar detection signal has stronger waveform distortion resistance and interference resistance, and is beneficial to improving the radar positioning and ranging precision.
Additional advantages and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following and practice of the invention.
Detailed Description
The present invention is described in further detail below with reference to examples to enable those skilled in the art to practice the same by referring to the description.
In the prior art, radar positioning ranging is usually performed by directly comparing peak points of a detection signal and a reflected signal to calculate time delay; however, the method is easily affected by factors such as waveform distortion, sampling clock jitter, channel interference and the like, so that the compared peak point is not a real peak point, delay measurement errors are easily caused, and thus, radar positioning and ranging errors are caused.
In order to solve the technical problems in the prior art, the embodiment of the invention discloses a radar positioning and ranging method based on spread spectrum time domain reflection. The method comprises the following steps:
step one: transmitting the spread spectrum probe signal and waiting to receive the reflected signal.
Step two: an autocorrelation signal of the spread spectrum detection signal and an autocorrelation signal of the reflected signal are calculated, respectively.
Step three: in order to reduce the difficulty of capturing peak values of comparison signals and improve the accuracy of comparison, the autocorrelation signals of the spread spectrum detection signals and the reflected signals are solved, and then the autocorrelation signals are sampled to obtain sample data [ X, Y ] of the autocorrelation signals of the spread spectrum detection signals]And sample data [ P, Q ] of the autocorrelation signal of the reflected signal]. Specifically, the autocorrelation signal of the spread spectrum detection signal is sampled to obtain sample data of the autocorrelation signal of the spread spectrum detection signal, which is denoted as sample data [ X, Y ]]={(x 1 ，y 1 )，(x 2 ，y 2 )，…，(x i ，y i )，…，(x N ，y N ) And } wherein,x i 、y i the first of the autocorrelation signals respectively representing the spread spectrum detection signalsiSample time point and the firstiThe magnitude of the amplitude value is calculated,Nrepresenting the number of sampling time points; sampling the autocorrelation signal of the reflected signal to obtain sample data of the autocorrelation signal of the reflected signal, denoted as sample data [ P, Q ]]={(p 1 ，q 1 )，(p 2 ，q 2 )，…，(p i ，q i )，…，(p N ，q N ) And } wherein,p i 、q i the first of the autocorrelation signals respectively representing the reflected signalsiSample time point and the firstiThe magnitude of the amplitude value is calculated,Nthe number of sampling time points is represented.
Step four: calculating a cost function J (θ) of an autocorrelation signal of the spread spectrum detection signal:
，
wherein,is a fitting function and->，MRepresents the number of sample data, θ is the fitting vector and θ= (θ) 0 ，θ 1 ，θ 2 )，θ 0 、θ 1 、θ 2 A first element, a second element and a third element respectively representing a fitting vector θ; solving for θ when minimizing cost function J (θ) 0 、θ 1 、θ 2 Is a value of (2);
calculating a cost function ψ (γ) of an autocorrelation signal of the reflected signal:
，
wherein,is a fitting function and->，MRepresents the number of sample data, γ represents the fitting vector and γ= (γ) 0 ，γ 1 ，γ 2 )，γ 0 、γ 1 、γ 2 The first element, the second element and the third element of the fitting vector gamma are respectively represented; solving for gamma when minimizing cost function ψ (gamma) 0 、γ 1 、γ 2 Is a value of (2).
Step five: calculating a delay time of an autocorrelation signal of the spread spectrum detection signal and an autocorrelation signal of the reflected signalτThe delay timeτThe method comprises the following steps:
，
wherein θ 0 、θ 1 、θ 2 、γ 0 、γ 1 、γ 2 Solving the obtained value in the fourth step;
step six: calculating radar ranging sized，WhereinvIs the propagation velocity of electromagnetic waves.
In the technical scheme disclosed by the embodiment of the invention, in order to reduce the capture difficulty of the peak value of the comparison signal and improve the accuracy of the comparison, the autocorrelation signals of the spread spectrum detection signal and the reflection signal are solved, and then the autocorrelation signals are sampled to respectively obtain sample data [ X, Y ] of the autocorrelation signals of the spread spectrum detection signal and sample data [ P, Q ] of the autocorrelation signals of the reflection signal.
Further, in the technical scheme disclosed by the embodiment of the invention, the fitting vector theta= (theta) when the cost function J (theta) is minimum is solved by adopting a plurality of iterative operations and a rapid gradient descent method 0 ，θ 1 ，θ 2 ) Values. Setting a fitting function based on sampling data of the spread spectrum detection signalBy iterative operation and a rapid gradient descent method, a fitting vector θ= (θ) at which the cost function J (θ) is minimized is calculated 0 ，θ 1 ，θ 2 ) Values to achieve the purpose of data fitting. Similarly, based on the sampled data of the reflected signal, a fitting function is set +.>Calculating the cost function through iterative operation and a rapid gradient descent methodFitting vector γ= (γ) when number ψ (γ) is minimum 0 ，γ 1 ，γ 2 ) Values to achieve the purpose of data fitting. And finally, calculating the time delay and the positioning distance by using the fitting vector value of the spread spectrum detection signal and the fitting vector value of the reflection signal.
Further, in the technical solution disclosed in the embodiment of the present invention, a fitting vector θ= (θ) when the cost function J (θ) is minimized is solved 0 ，θ 1 ，θ 2 ) Comprising the steps of:
step one: setting θ 0 、θ 1 、θ 2 Initial values of (1) are respectively recorded as、/>、/>The method comprises the steps of carrying out a first treatment on the surface of the Typically, θ 0 、θ 1 、θ 2 Is zero.
Step two: from sample data [ X, Y]={(x 1 ，y 1 )，(x 2 ，y 2 )，…，(x i ，y i )，…，(x N ，y N ) Random decimation in }MThe sample data are grouped into a subset of sample data, whereinM＜N，
；
Step three: solving for、/>、/>Wherein, the method comprises the steps of, wherein,
，
，
；
wherein,；
step four: updating theta 0 、θ 1 、θ 2 Wherein, in the values of (c), wherein,
，
，
；
wherein,μis a gradient descent factor; typically, the gradient descent factorμThe value range of (2) is 1-10.
Step five: will be theta 0 、θ 1 、θ 2 And substituting the value of (c) into J (θ), calculating and recording the value of J (θ), wherein,
；
step six: repeating the contents of the second to fifth steps, and taking the corresponding value of J (theta) when the execution times K are the smallestθ 0 、θ 1 、θ 2 The value of θ= (θ) as the fitting vector 0 ，θ 1 ，θ 2 ) Is a value of (2).
Further, in the technical scheme disclosed in the embodiment of the present invention, a fitting vector γ= (γ) when a cost function ψ (γ) is minimized is solved 0 ，γ 1 ，γ 2 ) The method of (2) comprises the following steps:
step one: setting gamma 0 、γ 1 、γ 2 Initial values of (1) are respectively recorded as、/>、/>The method comprises the steps of carrying out a first treatment on the surface of the Typically, gamma 0 ，γ 1 ，γ 2 The initial value is 0.
Step two: from sample data [ P, Q]={(p 1 ，q 1 )，(p 2 ，q 2 )，…，(p i ，q i )，…，(p N ，q N ) Random decimation in }MThe sample data are grouped into a subset of sample data, whereinM＜N，
；
Step three: solving for、/>、/>The method comprises the steps of carrying out a first treatment on the surface of the Wherein,
，
，
；
wherein,；
step four: updatingγ 0 、γ 1 、γ 2 Wherein, in the values of (c), wherein,
，
，
；
wherein,μis the gradient descent factor and is used to determine,the method comprises the steps of carrying out a first treatment on the surface of the Typically, the gradient descent factorμThe value range of (2) is 1-10.
Step five: will beγ 0 、γ 1 、γ 2 Is substituted into the value of ψ (y), the value of ψ (y) is calculated and recorded, wherein,
；
step six: repeating the contents of the second to fifth steps, wherein the execution times K are the corresponding times when the value of ψ (gamma) is the minimumγ 0 、γ 1 、γ 2 The value of gamma= (gamma) as the fitting vector 0 ，γ 1 ，γ 2 ) Is a value of (2).
Typically, in the technical solution disclosed in the embodiment of the present invention, the complexity and the real-time requirement of radar positioning ranging are comprehensively considered, and the execution frequency k=20.
In the technical scheme disclosed by the embodiment of the invention, the peak points of the autocorrelation signals of the spread spectrum detection signals and the reflection signals are accurately captured by adopting the data fitting and numerical calculation modes, rather than directly comparing the peak points of the detection signals and the reflection signals to calculate the transmission delay so as to obtain the positioning distance; the technical scheme disclosed by the embodiment of the invention is less influenced by sampling clock jitter and waveform distortion. In the prior art, the positioning distance is usually obtained by directly comparing peak points of the detection signal and the reflection signal to calculate the transmission delay, and the prior art scheme is easily affected by factors such as waveform distortion, sampling clock jitter, channel interference and the like, so that the compared peak points are not real peak points, thereby causing delay measurement errors and causing radar positioning ranging errors. Compared with the prior art, the technical scheme disclosed by the embodiment of the invention improves the accuracy of radar positioning and ranging.
In the technical scheme disclosed in the embodiment of the invention, the detection signal emitted by the radar is a spread spectrum detection signal, and in the first stepkThe spread spectrum detection signal in the repetition period time is as follows:
wherein,c j for the number of chipsFPseudo-random sequence of (c)jThe amplitude of the individual chips is determined,γ(t) In order to shape the pulse(s),τ pulse for shaping the pulseγ(t) Is used for the time width of (a),f c for the carrier frequency of the spread spectrum probe signal,μfor the frequency modulation slope,φ k is the firstkInitial phase of each repetition period.
In the prior art, the basic waveform of a detection signal emitted by radar positioning ranging mainly adopts continuous waves and pulse modulation waves, and the shaping pulse of the system detection signal usually adopts a rectangular function. The rectangular function is used as a shaping pulse, and is characterized in that the detection signal has larger side lobe amplitude,the main lobe has poor energy aggregation; when the system detection signal passes through band-pass devices such as antenna filtering, partial sidelobe energy is filtered; the large side lobe amplitude of the rectangular function causes the filtered side lobe energy to cause a large waveform distortion of the detection signal transmitted to the channel, which is very disadvantageous for capturing the peak points of the spread spectrum detection signal and the reflected signal. In order to solve the problems existing in the prior art, to improve the energy aggregation of the detection signal and reduce the distortion of the detection signal, in the technical scheme disclosed by the embodiment of the invention, the pulse waveform is formedγ(t) Is cos 2 A bell-shaped pulse, said cos 2 The rise time of the bell-shaped pulse is: (2.5.+ -. 0.5) μ s, fall time is: (2.5.+ -. 0.5) μ s. cos 2 The bell-shaped pulse has lower side lobe amplitude and higher main lobe energy concentration than the rectangular pulse.
In the prior art, the positioning distance is usually obtained by directly comparing peak points of the detection signal and the reflection signal to calculate the transmission delay, and the method is suitable for signal waveforms with sharp peak characteristics, but is not suitable for signal waveforms with gentle waveform amplitude variation; therefore, the method has a large application limitation. In order to solve the problems in the prior art, in the technical scheme disclosed by the embodiment of the invention, two technical characteristics are adopted to solve the problems; firstly, in order to reduce the difficulty of capturing the peak value of the comparison signal and improve the accuracy of the comparison, the compared object is not a detection signal and a reflection signal, but is an autocorrelation signal of the detection signal and the reflection signal, and the autocorrelation signal has obvious peak value characteristics relative to the detection signal and the reflection signal; secondly, the detection signal carries a pseudo-random sequence with good autocorrelation characteristics, the pseudo-random sequence enables the autocorrelation signals of the detection signal and the reflection signal to have sharp peak characteristics, the peak time point of the autocorrelation signals is easier to capture, the time delay of the detection signal and the reflection signal can be accurately calculated, and the radar positioning and ranging precision is improved. Typically, in the technical solution disclosed in the embodiments of the present invention, the pseudo-random sequence may use an M-sequence, a barker sequence, and the like.
Further, the pseudo-random sequence adopted by the embodiment of the invention expands the energy of the detection signal to a wider frequency spectrum range, thereby obviously improving the hiding capability and the anti-interference capability of the radar detection signal and improving the reliability of radar positioning and ranging. Compared with the prior art, the technical scheme disclosed by the embodiment of the invention ensures that the radar detection signal has stronger waveform distortion resistance and interference resistance, and is beneficial to improving the reliability of radar positioning and ranging.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (6)
1. A radar positioning and ranging method based on spread spectrum time domain reflection is characterized by comprising the following steps:
step one: transmitting a spread spectrum detection signal and waiting for receiving a reflected signal;
step two: respectively calculating an autocorrelation signal of the spread spectrum detection signal and an autocorrelation signal of the reflection signal;
step three: sampling the autocorrelation signal of the spread spectrum detection signal to obtain sample data of the autocorrelation signal of the spread spectrum detection signal, and recording the sample data as sample data [ X, Y ]]={(x 1 ，y 1 )，(x 2 ，y 2 )，…，(x i ，y i )，…，(x N ，y N ) And } wherein,x i 、y i the first of the autocorrelation signals respectively representing the spread spectrum detection signalsiSample time point and the firstiThe magnitude of the amplitude value is calculated,Nrepresenting the number of sampling time points; sampling the autocorrelation signal of the reflected signal to obtain sample data of the autocorrelation signal of the reflected signal, denoted as sample data [ P, Q ]]={(p 1 ，q 1 )，(p 2 ，q 2 )，…，(p i ，q i )，…，(p N ，q N ) And } wherein,p i 、 q i the first of the autocorrelation signals respectively representing the reflected signalsiSample time point and the firstiThe magnitude of the amplitude value is calculated,Nrepresenting the number of sampling time points;
step four: calculating a cost function J (θ) of an autocorrelation signal of the spread spectrum detection signal:
，
wherein,is a fitting function and->，MRepresents the number of sample data, θ is the fitting vector and θ= (θ) 0 ，θ 1 ，θ 2 )，θ 0 、θ 1 、θ 2 A first element, a second element and a third element respectively representing a fitting vector θ; solving for θ when minimizing cost function J (θ) 0 、θ 1 、θ 2 Is a value of (2);
calculating a cost function ψ (γ) of an autocorrelation signal of the reflected signal:
，
wherein,is a fitting function and->，MRepresents the number of sample data, γ represents the fitting vector and γ= (γ) 0 ，γ 1 ，γ 2 )，γ 0 、γ 1 、γ 2 Respectively represent the simulationCombining the first element, the second element and the third element of the vector gamma; solving for gamma when minimizing cost function ψ (gamma) 0 、γ 1 、γ 2 Is a value of (2);
step five: calculating a delay time of an autocorrelation signal of the spread spectrum detection signal and an autocorrelation signal of the reflected signalτThe delay timeτThe method comprises the following steps:
，
wherein θ 0 、θ 1 、θ 2 、γ 0 、γ 1 、γ 2 Solving the obtained value in the fourth step;
step six: calculating radar ranging sized，WhereinvIs the propagation velocity of electromagnetic waves.
2. The radar positioning and ranging method based on spread spectrum time domain reflection according to claim 1, wherein the method for solving the fitting vector θ when the cost function J (θ) is minimized is divided into the following steps:
step one: setting θ 0 、θ 1 、θ 2 Initial values of (1) are respectively recorded as、/>、/>；
Step two: from sample data [ X, Y]={(x 1 ，y 1 )，(x 2 ，y 2 )，…，(x i ，y i )，…，(x N ，y N ) Random decimation in }MThe sample data are grouped into a subset of sample data, whereinM＜N，
；
Step three: solving for、/>、/>Wherein, the method comprises the steps of, wherein,
，
，
；
wherein,；
step four: updating theta 0 、θ 1 、θ 2 Wherein, in the values of (c), wherein,
，
，
；
wherein,μis a gradient descent factor;
step five: will be theta 0 、θ 1 、θ 2 And substituting the value of (c) into J (θ), calculating and recording the value of J (θ), wherein,
；
step six: repeating the contents of the second to fifth steps, and taking the corresponding value of J (theta) when the execution times K are the smallestθ 0 、θ 1 、θ 2 The value of θ= (θ) as the fitting vector 0 ，θ 1 ，θ 2 ) Is a value of (2).
3. The radar positioning and ranging method based on spread spectrum time domain reflection according to claim 1, wherein the method for solving the fitting vector γ when the cost function ψ (γ) is minimized is divided into the following steps:
step one: setting gamma 0 、γ 1 、γ 2 Initial values of (1) are respectively recorded as、/>、/>；
Step two: from sample data [ P, Q]={(p 1 ，q 1 )，(p 2 ，q 2 )，…，(p i ，q i )，…，(p N ，q N ) Random decimation in }MThe sample data are grouped into a subset of sample data, whereinM＜N，
；
Step three: solving for、/>、/>The method comprises the steps of carrying out a first treatment on the surface of the Wherein,
，
，
；
wherein,；
step four: updatingγ 0 、γ 1 、γ 2 Wherein, in the values of (c), wherein,
，
，
；
wherein,μis a gradient descent factor;
step five: will beγ 0 、γ 1 、γ 2 Is substituted into the value of ψ (y), the value of ψ (y) is calculated and recorded, wherein,
；
step six: repeating the contents of the second to fifth steps, wherein the execution times K are the corresponding times when the value of ψ (gamma) is the minimumγ 0 、γ 1 、γ 2 The value of gamma= (gamma) as the fitting vector 0 ，γ 1 ，γ 2 ) Is a value of (2).
4. A method of radar positioning ranging based on spread spectrum time domain reflection according to claim 2 or 3, characterized in that in the firstkThe spread spectrum detection signal in the repetition period time is as follows:
，
wherein,c j for the number of chipsFPseudo-random sequence of (c)jThe amplitude of the individual chips is determined,γ(t) In order to shape the pulse(s),τ pulse for shaping the pulseγ(t) Is used for the time width of (a),f c for the carrier frequency of the spread spectrum probe signal,μfor the frequency modulation slope,φ k is the firstkInitial phase of each repetition period.
5. The method for radar location ranging based on spread spectrum time domain reflection according to claim 4, wherein said pulse waveformγ(t) Is cos 2 A bell-shaped pulse, said cos 2 The rise time of the bell-shaped pulse is: (2.5.+ -. 0.5) μ s, fall time is: (2.5.+ -. 0.5) μ s.
6. The method for radar positioning and ranging based on spread spectrum time domain reflection according to claim 5, wherein the number of executions k=20.
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