CN105044680A - Multiple-peak low-Doppler-sidelobe phase-coded signal design method - Google Patents

Abstract

The invention belongs to the radar technical field and discloses a multiple-peak low-Doppler-sidelobe phase-coded signal design method which can improve the performance of a radar. The phase-coded signal design method comprises the following steps: determining code element length of a phase-coded signal according to bandwidth of a radar transmitting signal and timewidth of the radar transmitting signal; determining the number of peaks of the phase-coded signal in the distance-Doppler dimension and the position of each peak in the distance-Doppler dimension; determining selection interval of Doppler frequency points of the phase-coded signal, and Doppler frequency band width for carrying out sidelobe suppression on the phase-coded signal, and determining the number of Doppler channels of the phase-coded signal in the distance-Doppler dimension; calculating sidelobe vector of each Doppler channel of the phase-coded signal; constructing an objective function according to the sidelobe vectors of all Doppler channels of the phase-coded signal; and solving the objective function to obtain the phase-coded signal.

Description

The phase-coded signal method for designing of the low Doppler sidelobne of multi-peak

Technical field

The invention belongs to Radar Technology field, specifically the phase-coded signal method for designing of the low Doppler sidelobne of a kind of multi-peak.

Background technology

Phase-coded signal is a kind of common pulse compression signal, compared with FM signal, phase-coded signal has more degree of freedom in the design, and phase-coded signal has the advantage such as low distance side lobe and low cross-correlation secondary lobe, therefore obtains extensive investigation and application.But phase-coded signal is Doppler-sensitive signals.When pulse compression filter cannot mate the Doppler frequency of the target echo signal received, after causing pulse compression, the reduction of main lobe amplitude and sidelobe level raise this two consequences, have had a strong impact on the detection performance of radar.

At present, the side lobe suppression method of phase-coded signal mainly contains classical window function weighted method, least square amplitude and phase weighting method and compression post-sampling slide window processing method etc.When not having Doppler mismatch, these three class methods can well suppress the secondary lobe after pulse pressure; But when there is Doppler mismatch, the inhibition meeting degradation of these three class methods, therefore, these three class methods cannot solve the sidelobe level caused by Doppler frequency mismatch and raise problem.

Reduce problem to solve the main lobe amplitude caused by Doppler frequency mismatch, radar adopts the Doppler frequency of one group of Doppler effect correction pulse compression filter to target echo to compensate usually when receiving target echo; And can be estimated the speed of target by the method.But if target velocity is very large, when radar carries out Doppler effect correction, Doppler effect correction pulse compression filter number can be a lot, like this by increasing the operand of signal transacting, affect the real-time of radar.According to the peak amplitude that Doppler effect correction pulse compression filter exports, the speed of target can be calculated, but the rate accuracy of the method is lower.

At present, the signal designing low distance side lobe and cross-correlation secondary lobe is mainly devoted in phase-coded signal design, does not consider the problem reducing Doppler sidelobne, minimizing Doppler effect correction pulse compression filter number and improve rate accuracy.

Summary of the invention

For the problems referred to above, the object of the present invention is to provide the phase-coded signal method for designing of the low Doppler sidelobne of a kind of multi-peak, to solve the sidelobe level rising because Doppler frequency mismatch causes, when target velocity causes greatly Doppler effect correction, Doppler effect correction pulse compression filter too much and the low problem of rate accuracy, for suppressing the Doppler sidelobne of phase-coded signal, improving the Doppler effect correction channel number of the rate accuracy of radar and minimizing radar, and then improve radar performance.

Realizing technical thought of the present invention is: according to the normalized Doppler frequency range of target and each peak value occurs in distance-Doppler dimension position, with the Doppler sidelobne peak level minimized in twice Doppler frequency range with each peak value is approached respectively the peak amplitude of expectation for objective function, designed phase coded signal.

For achieving the above object, embodiments of the invention adopt following technical scheme to be achieved.

A phase-coded signal method for designing for the low Doppler sidelobne of multi-peak, described method comprises the steps:

Step 1, according to the time wide Baud Length determining phase-coded signal of the bandwidth sum radar emission signal of radar emission signal, described phase-coded signal is the detectable signal of radar emission;

Step 2, determines the peak value number of described phase-coded signal in distance-Doppler dimension, and the position of each peak value in distance-Doppler dimension;

Step 3, that determines the Doppler frequency point of described phase-coded signal chooses interval, and phase-coded signal is carried out to the Doppler bin width of Sidelobe Suppression, and according to described Doppler frequency point choose interval and described Doppler bin width determines the Doppler channel number of described phase-coded signal in Doppler's dimension;

Step 4, calculates the secondary lobe vector of each Doppler's passage of described phase-coded signal;

Step 5, according to the secondary lobe vector of all Doppler's passages of described phase-coded signal, establishing target function;

Step 6, solves described objective function, obtains described phase-coded signal.

The feature of this programme and being further improved to:

(1) step 1 specifically comprises: according to the bandwidth B of radar emission signal and the time wide T of radar emission signal _pobtain the Baud Length N of described phase-coded signal _s=ceil (B × T _p), wherein, ceil () represents the number that rounds up.

(2) the peak value number N of described phase-coded signal in distance-Doppler dimension is determined in step 2, wherein, N >=3, and be odd number;

N number of peak value of described phase-coded signal is about the point (N on the distance-Doppler dimension X-Y scheme of described phase-coded signal _s, 0) and symmetrical, wherein N _srepresent the Baud Length of described phase-coded signal, 0 represents zero Doppler frequency in Doppler's dimension.

(3) in step 2, the absolute value of the Doppler frequency that the position of each peak value in distance-Doppler dimension is corresponding is less than or equal to the normalization maximum doppler frequency of phase-coded signal, and the position of described each peak value in Doppler's dimension is not identical.

Further, M is made to represent the peak value number that Doppler frequency corresponding to position in N number of peak value of described phase-coded signal in distance-Doppler dimension is greater than zero, then the peak value number N=2M+1 that described phase-coded signal is total;

Arranging the position that Doppler frequency corresponding to the position in Doppler's dimension of described phase-coded signal be greater than M the peak value of zero is:

(n ₁，m ₁)，…，(n _l，m _l)，…，(n _M，m _M)

Wherein l ∈ [1, M], n _lrepresent l point in distance dimension, m _lexpression Doppler ties up l the point that Doppler frequency is greater than zero, and M value is positive integer;

Then the position of the minus M of the Doppler frequency peak value that the position in Doppler's dimension of described phase-coded signal is corresponding is:

(2N _s-n ₁，-m ₁)，…，(2N _s-n _l，-m _l)，…，(2N _s-n _M，-m _M)

Wherein, 2N _s-n _lrepresent n _lpoint is about the upper N of distance dimension _sindividual point-symmetric point ,-m _lrepresent that Doppler ties up minus l the point of Doppler frequency; To arrange Doppler frequency corresponding to the position in Doppler's dimension of described phase-coded signal be the position of the peak value of zero is (N _s, m ₀).

(4) following sub-step is specifically comprised in step 3:

(3a) maximum doppler frequency of described phase-coded signal is determined wherein v _maxfor the maximum radial speed of target, λ is the wavelength of radar emission signal;

(3b) the normalization maximum doppler frequency of described phase-coded signal is determined and the normalization minimum Doppler frequency f of described phase-coded signal _dmin=-f _dmax, wherein, B is the bandwidth of radar emission signal;

(3c) according to the normalization maximum doppler frequency f of described phase-coded signal _dmaxwith the normalization minimum Doppler frequency f of described phase-coded signal _dmix, obtain the Doppler bin width f described phase-coded signal being carried out to Sidelobe Suppression _width=2 × (f _dmax-f _dmin), wherein × represent multiplication sign.

(3d) suppose that the Doppler frequency resolution of radar is Δ f _d, then according to the Doppler frequency resolution Δ f of radar _dthat determines the Doppler frequency point of phase-coded signal chooses interval delta f ' _d, make Δ f ' _d< Δ f _d;

(3e) according to the Doppler bin width f described phase-coded signal being carried out to Sidelobe Suppression _widthwith the Doppler frequency point of described phase-coded signal choose interval delta f ' _d, determine that described phase-coded signal is greater than Doppler's channel number N of 1 Doppler frequency point in Doppler's dimension _d1=ceil (f _width/ 2/ Δ f ' _d), wherein, ceil () represents the number that rounds up;

(3f) the Doppler channel number N of described phase-coded signal in Doppler's dimension _d=2N _d1+ 1.

(5) step 4 specifically comprises following sub-step:

(4a) interval delta f ' is chosen according to the Doppler frequency point of described phase-coded signal _din Doppler's dimension, Doppler's channel number N of 1 Doppler frequency point is greater than with described phase-coded signal _d1, obtain the Doppler frequency f of i-th Doppler's passage _di=i Δ f ' _d, then Doppler's guiding vector a of i-th Doppler's passage _ifor

$a_i\left(f_{di}\right)={\&lsqb;1,e^{j2{\mathrm{\&pi;f}}_{di}},e^{j2\mathrm{\&pi;}\&CenterDot;2\&CenterDot;f_{di}},...,e^{j2\mathrm{\&pi;}\&CenterDot;(c-1)\&CenterDot;f_{di}},...,e^{j2\mathrm{\&pi;}\&CenterDot;(N_s-1)\&CenterDot;f_{di}}\&rsqb;}^T$

Wherein i ∈ [0, N _d1], c ∈ [1, N _s];

(4b) suppose that phase-coded signal is s, then the phase-coded signal s ' of described i-th Doppler's passage _i=s ⊙ a _i(f _di), the phase-coded signal s ' of described i-th Doppler's passage _ithe result vector exported after device h is after filtering ρ _ci, wherein,

${\mathrm{\&rho;}}_{ci}=s_i^{\&prime;}\&CircleTimes;h={\&lsqb;{\mathrm{\&rho;}}_1,{\mathrm{\&rho;}}_2,...,{\mathrm{\&rho;}}_k,...,{\mathrm{\&rho;}}_{2N_s-1}\&rsqb;}^T$

represent convolution, [.] ^trepresent transposition, k ∈ [1,2N _s-1], N _srepresent the Baud Length of phase-coded signal, wave filter h is that conjugation is got in phase-coded signal s upset;

(4c) according to the phase-coded signal s ' of described i-th Doppler's passage _ithe result vector ρ exported after device h after filtering _ci, determine the secondary lobe vector ρ of i-th Doppler's passage _i.

Further, the secondary lobe vector ρ of i-th Doppler's passage is determined _ispecifically comprise:

Judge Doppler frequency f _diwhether at frequency separation [m ₀-1/N _s, m ₀+ 1/N _s] in, if Doppler frequency f _diin this frequency separation, and peak value m ₀point in corresponding distance dimension is n ₀, then vectorial ρ is removed _cin-th ₀individual point; Continue to judge Doppler frequency f _diwhether at frequency separation [m ₁-1/N _s, m ₁+ 1/N _s] in, if Doppler frequency f _diin this frequency separation, and peak value m ₁point in corresponding distance dimension is n ₁, then vectorial ρ is removed _cin-th ₁individual point; By that analogy, until judge Doppler frequency f _diwhether at frequency separation [m _m-1/N _s, m _m+ 1/N _s] in, if Doppler frequency f _diin this frequency separation, and peak value m _mpoint in corresponding distance dimension is n _m, then vectorial ρ is removed _cin-th _mindividual, remove vectorial ρ _cithe vector obtained after the point of middle correspondence is designated as vectorial ρ _i.

(6) step 5 specifically comprises following sub-step:

(5a) remember that the secondary lobe vector being more than or equal to Doppler's passage of zero Doppler frequency in Doppler's dimension is respectively the peak value that Doppler's dimension is more than or equal to Doppler's passage of zero Doppler frequency is respectively b ₁..., b _l..., b _m, wherein i ∈ [0, N _d1], l ∈ [1, M];

(5b) the p norm composition of vector ρ of the peak value of the secondary lobe vector sum Doppler passage of Doppler's passage is got respectively,

$\mathrm{\&rho;}=\&lsqb;\left|\right|{\mathrm{\&rho;}}_0|{|}_p,|\left|{\mathrm{\&rho;}}_1\right|{|}_p,...,\left|\right|{\mathrm{\&rho;}}_i|{|}_p,...,|\left|{\mathrm{\&rho;}}_{N_{d1}}\right|{|}_p,\left|\right|b_1|{|}_p,...,|\left|b_l\right|{|}_p,...,\left|\right|b_M|{|}_p\&rsqb;$

Wherein, || || _prepresent p norm;

(5c) suppose that the coefficient vector that in vectorial ρ, each element is corresponding is t ∈ [1, N _d1+ M+1], then establishing target function is:

Wherein, min represents and minimizes, || || _prepresent p norm, ⊙ represents dot product, and α is the phase vectors of phase-coded signal.

The present invention compared with prior art tool has the following advantages: one of criterion of (1) designed phase coded signal of the present invention minimizes Doppler sidelobne peak level, therefore solve the sidelobe level rising problem that prior art causes due to Doppler frequency mismatch, improve the performance of radar; (2) another criterion of designed phase coded signal of the present invention produces multi-peak in distance-Doppler dimension, and make multi-peak approach the peak value of expectation respectively, can solve target velocity excessive time, Doppler effect correction pulse compression filter number too much, can cause the problem that rate accuracy is low.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 of the present inventionly realizes general flow chart;

Fig. 2 is the sub-process figure of the present invention when using Least p-norm Algorithm for Solving radar waveform phase place;

Fig. 3 is the three-dimensional plot of phase-coded signal after each Doppler frequency pulse compression arranged in distance-Doppler dimension with the inventive method design, wherein, x-axis represents normalization Doppler frequency, and unit is Hz, y-axis represents distance displacement, and z-axis represents amplitude;

Fig. 4 suppresses frequency range place with phase-coded signal Doppler sidelobne after each Doppler frequency pulse compression arranged of the inventive method design and does not carry out the Doppler sidelobne comparison diagram that Doppler sidelobne suppresses frequency range place, wherein, x-axis represents normalization Doppler frequency, unit is Hz, y-axis represents distance displacement, and z-axis represents amplitude;

Fig. 5 is the circle of equal altitudes of phase-coded signal after each Doppler frequency pulse compression arranged in distance-Doppler dimension with the inventive method design.Wherein, horizontal ordinate represents normalization Doppler frequency, and unit is Hz, and ordinate represents distance displacement.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

With reference to Fig. 1, performing step of the present invention is as follows:

Step 1, according to the time wide Baud Length determining phase-coded signal of the bandwidth sum radar emission signal of radar emission signal, described phase-coded signal is the detectable signal of radar emission.

According to the bandwidth B of radar emission signal and the time wide T of radar emission signal _pobtain the Baud Length N of described phase-coded signal _s=ceil (B × T _p), wherein, ceil () represents the number that rounds up.

Step 2, determines the peak value number of described phase-coded signal in distance-Doppler dimension, and the position of each peak value in distance-Doppler dimension.

The rate accuracy of radar is relevant with the peak value number of phase-coded signal on distance-Doppler is tieed up, and the peak value number of phase-coded signal in distance-Doppler dimension is more, and the rate accuracy of radar is higher.But the peak value number of phase-coded signal in distance-Doppler dimension is more, the amplitude of the peak value of phase-coded signal can reduce relatively, and the amplitude of phase-coded signal secondary lobe also can raise relatively, and then affects the detection perform of radar.Therefore, in actual applications, compromise is needed to consider the rate accuracy of radar and the detection perform of radar, to determine the peak value number N of phase-coded signal in distance-Doppler dimension; Owing to carrying out pulse compression by the phase-coded signal of matched filter to design, therefore peak value number N >=3, and be odd number.

In Doppler's dimension, following principle is followed in the setting of the position of each peak value of phase-coded signal: first, and the absolute value of the Doppler frequency that the position of any peak value in Doppler's dimension of phase-coded signal is corresponding can not be greater than the normalization maximum doppler frequency f of phase-coded signal _dmax; Secondly, under the condition that the Doppler frequency that the position that each peak value of guarantee phase-coded signal occurs in Doppler's dimension is corresponding is different, the position of each peak value in Doppler's dimension of phase-coded signal is determined according to actual needs.In distance dimension, ensureing that under the condition that the position of each peak value of phase-coded signal in distance dimension is different, the position that each peak value of selected phase coded signal occurs as far as possible is from N _sthe position that individual point is nearer.N _sfor the Baud Length of described phase-coded signal.

Be N for Baud Length _sphase-coded signal, its ambiguity function figure is about the point (N on the distance-Doppler X-Y scheme of phase-coded signal _s, 0) and symmetrical, therefore, N number of peak value of phase-coded signal is also about the point (N on the distance-Doppler X-Y scheme of phase-coded signal _s, 0) symmetrical, wherein N _srepresent the N in distance dimension _sindividual, 0 represents zero Doppler frequency in Doppler's dimension.Due to the position of this N number of peak value, in advance people is for setting, therefore Distance geometry between every two peak values of this N number of peak value in distance-Doppler dimension and horizontal line angulation are all determined, and are unique; As long as therefore at least there are two peak values, just accurately can infer the position zero Doppler's passage, and then can accurately test the speed.

M is made to represent the peak value number that the Doppler frequency of the peak value position of phase-coded signal is greater than zero, then the peak value number N=2M+1 that phase-coded signal is total.

The position arranging this M peak value of phase-coded signal is

(n ₁，m ₁)，…，(n _l，m _l)，…，(n _M，m _M)

Wherein l ∈ [1, M], n _lrepresent l point in distance dimension, m _lexpression Doppler ties up l the point that Doppler frequency is greater than zero, and M value is positive integer.

Then the position of the minus M of the Doppler frequency peak value that the position of peak value in Doppler's dimension of phase-coded signal is corresponding is

(2N _s-n ₁，-m ₁)，…，(2N _s-n _l，-m _l)，…，(2N _s-n _M，-m _M)

Wherein, 2N _s-n _lrepresent n in distance dimension _lpoint is about the upper N of distance dimension _sindividual point-symmetric point ,-m _lrepresent that Doppler ties up minus l the point of Doppler frequency.The peak arranging the corresponding zero Doppler frequency place, the position of peak value in Doppler's dimension of phase-coded signal is (N _s, m ₀).

Due to the position of this N number of peak value, in advance people is for setting, therefore Distance geometry between every two peak values of this N number of peak value in distance-Doppler dimension and horizontal line angulation are all determined, and are unique; As long as therefore at least there are two peak values, just accurately can infer the position zero Doppler's passage, and then can accurately test the speed.

Step 3, that determines the Doppler frequency point of described phase-coded signal chooses interval, and phase-coded signal is carried out to the Doppler bin width of Sidelobe Suppression, and according to described Doppler frequency point choose interval and described Doppler bin width determines the Doppler channel number of described phase-coded signal in Doppler's dimension.

Following sub-step is specifically comprised in step 3:

(3a) maximum doppler frequency of described phase-coded signal is determined wherein v _maxfor the maximum radial speed of target, λ is the wavelength of radar emission signal.

(3b) the normalization maximum doppler frequency of described phase-coded signal is determined and the normalization minimum Doppler frequency f of described phase-coded signal _dmin=-f _dmaxwherein, B is the bandwidth of radar emission signal.

(3c) according to the normalization maximum doppler frequency f of described phase-coded signal _dmaxwith the normalization minimum Doppler frequency f of described phase-coded signal _dmix, obtain the Doppler bin width f described phase-coded signal being carried out to Sidelobe Suppression _width=2 × (f _dmax-f _dmin), wherein × represent multiplication sign.

Concrete, according to the carrier frequency of radar emission signal, the wavelength X of radar emission signal can be known; The target type that will be detected by radar, can determine the maximum radial speed v of target _max, can in the hope of the maximum doppler frequency of phase-coded signal by the maximum radial speed of target further according to the bandwidth B of radar emission signal, can in the hope of the normalization maximum doppler frequency of phase-coded signal and then the normalization minimum Doppler frequency f of phase-coded signal can be known _dmin=-f _dmax.According to the normalization maximum doppler frequency f of phase-coded signal _dmaxwith the normalization minimum Doppler frequency f of phase-coded signal _dmix, bin width f phase-coded signal being carried out to Doppler sidelobne suppression can be needed _width=2 × (f _dmax-f _dmin), wherein × represent multiplication sign.The frequency range of namely carrying out Doppler sidelobne suppression is [f _dmin, f _dmax].

(3d) suppose that the Doppler frequency resolution of radar is Δ f _d, then according to the Doppler frequency resolution Δ f of radar _dthat determines the Doppler frequency point of described phase-coded signal chooses interval delta f ' _d, make Δ f ' _d< Δ f _d.Wherein, Doppler frequency resolution Δ f _ddetermine according to the actual requirements.

(3e) according to the Doppler bin width f described phase-coded signal being carried out to Sidelobe Suppression _widthwith the Doppler frequency point of described phase-coded signal choose interval delta f ' _d, determine that described phase-coded signal is greater than Doppler's channel number N of 1 Doppler frequency point in Doppler's dimension _d1=ceil (f _width/ 2/ Δ f ' _d), wherein, ceil () represents the number that rounds up.

(3f) described phase-coded signal in Doppler's dimension-Doppler's channel number N _d=2N _d1+ 1.

Step 4, calculates the secondary lobe vector of each Doppler's passage of described phase-coded signal.

Because wave filter h is the matched filter of phase-coded signal s, therefore in Doppler's dimension, each Doppler's channel signal is symmetrical about zero Doppler frequency by the result after wave filter h.

Step 4 specifically comprises following sub-step:

(4a) interval delta f ' is chosen according to the Doppler frequency point of described phase-coded signal _din Doppler's dimension, Doppler's channel number N of 1 Doppler frequency point is greater than with described phase-coded signal _d1, obtain the Doppler frequency f of i-th Doppler's passage _di=i Δ f ' _d, then Doppler's guiding vector a of i-th Doppler's passage _ifor

$a_i\left(f_{di}\right)={\&lsqb;1,e^{j2{\mathrm{\&pi;f}}_{di}},e^{j2\mathrm{\&pi;}\&CenterDot;2\&CenterDot;f_{di}},...,e^{j2\mathrm{\&pi;}\&CenterDot;(c-1)\&CenterDot;f_{di}},...,e^{j2\mathrm{\&pi;}\&CenterDot;(N_s-1)\&CenterDot;f_{di}}\&rsqb;}^T$

Wherein i ∈ [0, N _d1], c ∈ [1, N _s].

(4b) suppose that phase-coded signal is s, then the phase-coded signal s ' of described i-th Doppler's passage _i=s ⊙ a _i(f _di), the phase-coded signal s ' of described i-th Doppler's passage _ithe result vector exported after device h is after filtering ρ _ci, wherein,

${\mathrm{\&rho;}}_{ci}=s_i^{\&prime;}\&CircleTimes;h={\&lsqb;{\mathrm{\&rho;}}_1,{\mathrm{\&rho;}}_2,...,{\mathrm{\&rho;}}_k,...,{\mathrm{\&rho;}}_{2N_s-1}\&rsqb;}^T$

represent convolution, [.] ^trepresent transposition, k ∈ [1,2N _s-1], N _srepresent the Baud Length of phase-coded signal, wave filter h is that conjugation is got in phase-coded signal s upset.

(4c) according to the phase-coded signal s ' of described i-th Doppler's passage _ithe result vector ρ exported after device h after filtering _ci, determine the secondary lobe vector ρ of i-th Doppler's passage _i.

Determine the secondary lobe vector ρ of i-th Doppler's passage _ispecifically comprise:

Judge Doppler frequency f _diwhether at frequency separation [m ₀-1/N _s, m ₀+ 1/N _s] in, if Doppler frequency f _diin this frequency separation, and peak value m ₀point in corresponding distance dimension is n ₀, then vectorial ρ is removed _cin-th ₀individual, otherwise, then need not remove vectorial ρ _cin-th ₀individual point; Continue to judge Doppler frequency f _diwhether at frequency separation [m ₁-1/N _s, m ₁+ 1/N _s] in, if Doppler frequency f _diin this frequency separation, and peak value m ₁point in corresponding distance dimension is n ₁, then vectorial ρ is removed _cin-th ₁individual, otherwise, then need not remove vectorial ρ _cin-th ₁individual point; By that analogy, until judge Doppler frequency f _diwhether at frequency separation [m _m-1/N _s, m _m+ 1/N _s] in, if Doppler frequency f _diin this frequency separation, and peak value m _mpoint in corresponding distance dimension is n _m, then vectorial ρ is removed _cin-th _mindividual, remove vectorial ρ _cithe vector obtained after the point of middle correspondence is designated as vector.

Step 5, according to the secondary lobe vector of described each Doppler's passage, establishing target function.

The position corresponding in Doppler's dimension due to each peak value of phase-coded signal is respectively m ₁..., m _l..., m _m; The amplitude of each peak value approaches Baud Length N _s, and be designated as b successively ₁..., b _l..., b _m, wherein, b _l=ρ _ci(n _l)-N _s, l ∈ [1, M], M value is positive integer.

Step 5 specifically comprises following sub-step:

(5a) remember that the secondary lobe vector being more than or equal to Doppler's passage of zero Doppler frequency in Doppler's dimension is respectively the peak value that Doppler's dimension is more than or equal to Doppler's passage of zero Doppler frequency is respectively b ₁..., b _l..., b _m, wherein i ∈ [0, N _d1], l ∈ [1, M].

(5b) the p norm composition of vector ρ of the peak value of the secondary lobe vector sum Doppler passage of Doppler's passage is got respectively,

$\mathrm{\&rho;}=\&lsqb;\left|\right|{\mathrm{\&rho;}}_0|{|}_p,|\left|{\mathrm{\&rho;}}_1\right|{|}_p,...,\left|\right|{\mathrm{\&rho;}}_i|{|}_p,...,|\left|{\mathrm{\&rho;}}_{N_{d1}}\right|{|}_p,\left|\right|b_1|{|}_p,...,|\left|b_l\right|{|}_p,...,\left|\right|b_M|{|}_p\&rsqb;$

Wherein, || || _prepresent p norm.

(5c) suppose that the coefficient vector that in vectorial ρ, each element is corresponding is t ∈ [1, N _d1+ M+1], then establishing target function is:

Wherein, min represents and minimizes, || || _prepresent p norm, ⊙ represents dot product, and α is the phase vectors of phase-coded signal.Each element inside coefficient vector k is the arithmetic number of artificial setting, for the effect that compromise Sidelobe Suppression effect and multi-peak main lobe approach, the value of coefficient vector k is selected respectively in the scope of [0,1], then adjusts according to actual needs.Step 6, solves described objective function, obtains described phase-coded signal.

Adopt the concrete sub-step based on the objective function of the optimized algorithm solution procedure 5 of the Least p-norm of L-BFGS, comprising:

(6a) defined function: f (α)=|| k ⊙ ρ || _p, wherein, || || _prepresent p norm, α is the phase vectors of phase-coded signal, [] ^trepresent transposition.

(6b) initialization, arranges the initial value α of vector ₀with minimum descent ε ₁initial value, make iterations n=1, norm p=2, multiplier μ=2, function initial value f ₀=100.

(6c) by using document [WangYC, WangX, LiuHW, etal.OntheDesignofConstantModulusProbingSignalsforMIMORa darSignalProcessing [J] .IEEETransactionsonSignalProcessing, 2012,60 (8): 4432-4438.] L-BFGS algorithmic minimizing function f (α), wherein, the update times m=5 of L-BFGS algorithm, vectorial α _n-1as the initial value of L-BFGS algorithm, optimum results is vectorial α _n, make f _n=f (α _n).

If (6d) | f _n-f _n-1| < ε ₁, then output vector α _nand stop circulation; Otherwise iterations n adds 1, and makes norm p _n=μ p _n-1, skip to sub-step (6c).

(6e) the vectorial α obtained by above-mentioned sub-step _n, determine vectorial α=α _n, and then obtaining the phase-coded signal of expectation: s=exp (j α), wherein, exp () represents index, and j is imaginary unit.

Effect of the present invention is further illustrated by following emulation experiment:

Simulation parameter arranges as follows: the length N of phase-coded signal _s=128, Doppler's channel number N of phase-coded signal _d=33, the known number N being greater than 1 Doppler frequency point _d1=16; Normalized maximum doppler frequency is f _dmax=2/N _s, total number N=5 of peak value, wherein in Doppler's dimension, the multi-peak position that doppler position is more than or equal to zero is respectively (N in distance-Doppler dimension _s-8,2/N _s), (N _s, 0), (N _s+ 12,2/N _s); Doppler frequency point choose interval delta f ' _d=0.25/N _s, need the bin width f suppressing Doppler sidelobne _width=8/N _s; Weight coefficient $k_1=k_2=...=k_{ii}=...=k_{N_{d1}+1}=0.99,k_{N_{d1}+2}=k_{N_{d1}+3}=...=k_{tt}=...=k_{N_{d1}+M+1}=0.2,$ Wherein ii ∈ [1, N _d1+ 1], tt ∈ [N _d1+ 2, N _d1+ M+1].

First, the objective function of phase-coded signal is built according to above-mentioned parameter.Then, according to the flow process coding shown in Fig. 2 on MATLAB software, solve the phase-coded signal obtaining expecting.

According to designing the phase-coded signal obtained, calculating the pulse compression result of phase-coded signal at each Doppler frequency place arranged, result being lined up matrix form, after delivery, is drawn as three-dimensional picture, as shown in Figure 3.The width of Doppler bin is increased by 0.5 times, and the interval of choosing of Doppler frequency point remains unchanged, and calculates phase-coded signal in the pulse compression result at each Doppler frequency place, result is lined up matrix form, is drawn as three-dimensional picture after delivery, as shown in Figure 4.Calculate the pulse compression result of phase-coded signal at each Doppler frequency place arranged, result is lined up matrix form, is drawn as contour figure after delivery, as shown in Figure 5.

As shown in Figure 3, the secondary lobe of phase-coded signal after each Doppler frequency place pulse compression arranged is obtained for suppression, maintains lower side lobe peak level.As shown in Figure 4, generally strangle secondary lobe the Doppler frequency place peak value not carrying out Sidelobe Suppression is more much higher, and be starkly lower than the former and amplitude is smooth at the Doppler frequency place Doppler sidelobne carrying out Sidelobe Suppression.Fig. 3 and Fig. 4 illustrates Doppler's sensitivity of the phase-coded signal that the inventive method reduces, and solves the sidelobe level rising problem because Doppler frequency mismatch causes.

As shown in Figure 5, this phase-coded signal of design after each Doppler frequency place pulse compression arranged, at assigned address (N _s-12,2/N _s), (N _s-8,1/N _s), (N _s, 0), (N _s+ 8,1/N _s), (N _s+ 12,2/N _s) there are 5 peak values, peak value is respectively 63.3747,63.3741,128,63.3741,63.3747, and corresponding peak sidelobe is respectively-12.9947dB ,-12.9829dB ,-19.1789dB ,-12.9829dB ,-12.9947dB.

Utilize ' star-plot ' i.e. multi-peak phase-coded signal that the method design obtains in actual applications, according to peak value number being detected, the amplitude height of peak value and the position of peak value, detect the speed of target; The method only occurring peak value at zero Doppler frequency passage proximate relatively, this aspect method can according to the peak preset in ' star-plot ' and the actual peak occurred, Distance geometry arbitrarily between every two peak values in distance-Doppler dimension and horizontal line angulation are all determined, and are unique; As long as therefore at least there are two peak values, just accurately can infer the position zero Doppler's passage, and then can accurately test the speed, therefore the inventive method can improve the rate accuracy of target.Normal conditions, in distance-Doppler dimension, produce single-peaked Doppler effect correction scope for [f _dmin, f _dmax], under the inventive method, because the position of ' star-plot ' multi-peak sets in advance, and at [f _dmin, f _dmax] in scope, as long as occur in ' star-plot ' being no less than two peak values, just can going out the speed of target by Accurate Estimation, therefore when ensureing appearance two peak values, the compensation channels number that namely Doppler effect correction scope reduces Doppler can be reduced.

The above; be only the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; change can be expected easily or replace, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of described claim.

Claims (9)

1. a phase-coded signal method for designing for the low Doppler sidelobne of multi-peak, is characterized in that, described method comprises the steps:

Step 1, according to the time wide Baud Length determining phase-coded signal of the bandwidth sum radar emission signal of radar emission signal, described phase-coded signal is the detectable signal of radar emission;

Step 2, determines the peak value number of described phase-coded signal in distance-Doppler dimension, and the position of each peak value in distance-Doppler dimension;

Step 3, that determines the Doppler frequency point of described phase-coded signal chooses interval, and phase-coded signal is carried out to the Doppler bin width of Sidelobe Suppression, and according to described Doppler frequency point choose interval and described Doppler bin width determines the Doppler channel number of described phase-coded signal in Doppler's dimension;

Step 4, calculates the secondary lobe vector of each Doppler's passage of described phase-coded signal;

Step 5, according to the secondary lobe vector of all Doppler's passages of described phase-coded signal, establishing target function;

Step 6, solves described objective function, obtains described phase-coded signal.

2. the phase-coded signal method for designing of the low Doppler sidelobne of multi-peak according to claim 1, it is characterized in that, step 1 specifically comprises:

According to the bandwidth B of radar emission signal and the time wide T of radar emission signal _pobtain the Baud Length N of described phase-coded signal _s=ceil (B × T _p), wherein, ceil () represents the number that rounds up.

3. the phase-coded signal method for designing of the low Doppler sidelobne of multi-peak according to claim 1, is characterized in that, determines the peak value number N of described phase-coded signal in distance-Doppler dimension in step 2, wherein, and N >=3, and be odd number;

N number of peak value of described phase-coded signal is about the point (N on the distance-Doppler dimension X-Y scheme of described phase-coded signal _s, 0) and symmetrical, wherein N _srepresent the Baud Length of described phase-coded signal, 0 represents zero Doppler frequency in Doppler's dimension.

4. the phase-coded signal method for designing of the low Doppler sidelobne of multi-peak according to claim 1, it is characterized in that, in step 2, the absolute value of the Doppler frequency that the position of each peak value in distance-Doppler dimension is corresponding is less than or equal to the normalization maximum doppler frequency of phase-coded signal, and the position of described each peak value in distance-Doppler dimension is not identical.

5. the phase-coded signal method for designing of the low Doppler sidelobne of multi-peak according to claim 4, is characterized in that,

M is made to represent the peak value number that Doppler frequency corresponding to position in N number of peak value of described phase-coded signal in distance-Doppler dimension is greater than zero, then total peak value number N=2M+1 of described phase-coded signal;

Arranging the position that Doppler frequency corresponding to the position in Doppler's dimension of described phase-coded signal be greater than M the peak value of zero is:

(n ₁,m ₁),…,(n _l,m _l),…,(n _M,m _M)

Wherein l ∈ [1, M], n _lrepresent l point in distance dimension, m _lexpression Doppler ties up l the point that Doppler frequency is greater than zero, and M value is positive integer;

Then the position of the minus M of the Doppler frequency peak value that the position in Doppler's dimension of described phase-coded signal is corresponding is:

(2N _s-n ₁,-m ₁),…,(2N _s-n _l,-m _l),…,(2N _s-n _M,-m _M)

Wherein, 2N _s-n _lrepresent n _lpoint is about the upper N of distance dimension _sindividual point-symmetric point ,-m _lrepresent that Doppler ties up minus l the point of Doppler frequency; To arrange Doppler frequency corresponding to the position in Doppler's dimension of described phase-coded signal be the position of the peak value of zero is (N _s, m ₀).

6. the phase-coded signal method for designing of the low Doppler sidelobne of multi-peak according to claim 1, is characterized in that, specifically comprises following sub-step in step 3:

(3a) maximum doppler frequency of described phase-coded signal is determined wherein v _maxfor the maximum radial speed of target, λ is the wavelength of radar emission signal;

(3b) the normalization maximum doppler frequency of described phase-coded signal is determined and the normalization minimum Doppler frequency f of described phase-coded signal _dmin=-f _dmax, wherein, B is the bandwidth of radar emission signal;

(3c) according to the normalization maximum doppler frequency f of described phase-coded signal _dmaxwith the normalization minimum Doppler frequency f of described phase-coded signal _dmix, obtain the Doppler bin width f described phase-coded signal being carried out to Sidelobe Suppression _width=2 × (f _dmax-f _dmin), wherein × represent multiplication sign;

(3d) suppose that the Doppler frequency resolution of radar is △ f _d, then according to the Doppler frequency resolution △ f of radar _dthat determines the Doppler frequency point of phase-coded signal chooses interval △ f ' _d, make △ f ' _d< △ f _d;

(3e) according to the Doppler bin width f described phase-coded signal being carried out to Sidelobe Suppression _widthand the Doppler frequency point of described phase-coded signal choose interval △ f ' _d, determine that described phase-coded signal is greater than Doppler's channel number N of 1 Doppler frequency point in Doppler's dimension _d1=ceil (f _width/ 2/ △ f ' _d), wherein, ceil () represents the number that rounds up;

(3f) the Doppler channel number N of described phase-coded signal in Doppler's dimension _d=2N _d1+ 1.

7. the phase-coded signal method for designing of the low Doppler sidelobne of multi-peak according to claim 1, is characterized in that, step 4 specifically comprises following sub-step:

(4a) interval △ f ' is chosen according to the Doppler frequency point of described phase-coded signal _din Doppler's dimension, Doppler's channel number N of 1 Doppler frequency point is greater than with described phase-coded signal _d1, obtain the Doppler frequency f of i-th Doppler's passage _di=i △ f ' _d, then Doppler's guiding vector a of i-th Doppler's passage _ifor

$a_i\left(f_{di}\right)={\&lsqb;1,e^{j2{\mathrm{\&pi;f}}_{di}},e^{j2\mathrm{\&pi;}\&CenterDot;2\&CenterDot;f_{di}},...,e^{j2\mathrm{\&pi;}\&CenterDot;(c-1)\&CenterDot;f_{di}},...,e^{j2\mathrm{\&pi;}\&CenterDot;(N_s-1)\&CenterDot;f_{di}}\&rsqb;}^T$

Wherein i ∈ [0, N _d1], c ∈ [1, N _s];

(4b) suppose that phase-coded signal is s, then the phase-coded signal s of described i-th Doppler's passage _i'=s ⊙ a _i(f _di), the phase-coded signal s of described i-th Doppler's passage _i' the result vector that exports after device h is after filtering ρ _ci, wherein,

${\mathrm{\&rho;}}_{ci}=s_i^{\&prime;}\&CircleTimes;h={\&lsqb;{\mathrm{\&rho;}}_1,{\mathrm{\&rho;}}_2,...,{\mathrm{\&rho;}}_k,...,{\mathrm{\&rho;}}_{2N_s-1}\&rsqb;}^T$

represent convolution, [.] ^trepresent transposition, k ∈ [1,2N _s-1], N _srepresent the Baud Length of phase-coded signal, wave filter h is that conjugation is got in phase-coded signal s upset;

(4c) according to the phase-coded signal s of described i-th Doppler's passage _i' result vector the ρ that exports after device h after filtering _ci, determine the secondary lobe vector ρ of i-th Doppler's passage _i.

8. the phase-coded signal method for designing of the low Doppler sidelobne of multi-peak according to claim 7, is characterized in that, determines the secondary lobe vector ρ of i-th Doppler's passage _ispecifically comprise:

Judge Doppler frequency f _diwhether at frequency separation [m ₀-1/N _s, m ₀+ 1/N _s] in, if Doppler frequency f _diin this frequency separation, and peak value m ₀point in corresponding distance dimension is n ₀, then vectorial ρ is removed _cin-th ₀individual point; Continue to judge Doppler frequency f _diwhether at frequency separation [m ₁-1/N _s, m ₁+ 1/N _s] in, if Doppler frequency f _diin this frequency separation, and peak value m ₁point in corresponding distance dimension is n ₁, then vectorial ρ is removed _cin-th ₁individual point; By that analogy, until judge Doppler frequency f _diwhether at frequency separation [m _m-1/N _s, m _m+ 1/N _s] in, if Doppler frequency f _diin this frequency separation, and peak value m _mpoint in corresponding distance dimension is n _m, then vectorial ρ is removed _cin-th _mindividual, remove vectorial ρ _cithe vector obtained after the point of middle correspondence is designated as vectorial ρ _i.

9. the phase-coded signal method for designing of the low Doppler sidelobne of multi-peak according to claim 1, is characterized in that, step 5 specifically comprises following sub-step:

(5a) remember that the secondary lobe vector being more than or equal to Doppler's passage of zero Doppler frequency in Doppler's dimension is respectively the peak value that Doppler's dimension is more than or equal to Doppler's passage of zero Doppler frequency is respectively b ₁..., b _l..., b _m, wherein i ∈ [0, N _d1], l ∈ [1, M], N _d1represent that described phase-coded signal is greater than Doppler's channel number of 1 Doppler frequency point in Doppler's dimension, M represents the peak value number that Doppler frequency corresponding to position in N number of peak value of described phase-coded signal in distance-Doppler dimension is greater than zero;

(5b) the p norm composition of vector ρ of the peak value of the secondary lobe vector sum Doppler passage of Doppler's passage is got respectively,

$\mathrm{\&rho;}=\&lsqb;\left|\right|{\mathrm{\&rho;}}_0|{|}_p,|\left|{\mathrm{\&rho;}}_1\right|{|}_p,...,\left|\right|{\mathrm{\&rho;}}_i|{|}_p,...,|\left|{\mathrm{\&rho;}}_{N_{d1}}\right|{|}_p,\left|\right|b_1|{|}_p,...,|\left|b_l\right|{|}_p,...,\left|\right|b_M|{|}_p\&rsqb;$

Wherein, || || _prepresent p norm;

(5c) suppose that the coefficient vector that in vectorial ρ, each element is corresponding is t ∈ [1, N _d1+ M+1], then establishing target function is:

Wherein, min represents and minimizes, || || _prepresent p norm, ⊙ represents dot product, and α represents the phase vectors of phase-coded signal.