CN105093191A - Direct wave recovery method for external radiation source radar - Google Patents

Abstract

The invention discloses a direct wave recovery method for external radiation source radar. The method comprises: S101, receiving, by a reference channel of the external radiation source radar, diversity signals of a plurality of diversity channels through a space diversity method; S102, processing the diversity signals of each diversity channel by adopting a one-path equalizer to obtain multi-path equalizer output signals; S103, summating the multi-path equalizer output signals to obtain direct wave signals; S104, calculating an error term according to the direct wave signals; S105, calculating a mean square error according to the error term, and judging whether the mean square error is smaller than a preset threshold; S106, if the mean square error is not smaller than the preset threshold, returning to S104 to calculate next error term; and S107, if the mean square error is smaller than the preset threshold, iterating the vectors of the equalizers every Ng sampling points. The method is small in calculation quantity and easy to implement in engineering.

Description

External illuminators-based radar direct wave restoration methods

Technical field

The present invention relates to Radar Technology field, particularly relate to a kind of external illuminators-based radar direct wave restoration methods.

Background technology

Direct wave recovery is the gordian technique of frequency modulation broadcasting external illuminators-based radar.Along with system is in the application of near cities or mountain area environment, serious environment clutter makes external illuminators-based radar direct wave recover to become very difficult.Traditional direct wave recovers the main lobe collimation arrived wave signal direction adopting Wave beam forming, utilizes the suppression of direct wave antenna side lobe realization to multipath signal.In heavy multipath situation, multipath clutter enters from main lobe, causes distorted signals.Adopt constant mould Blind Equalization Technique can realize direct wave equally to purify, comprise the multipath conditions simultaneously entering main lobe.When heavy multipath, the constringency performance of constant modeling method is poor.And space diversity blind balance method can adapt to the situation of heavy multipath, strengthen the recovery capability of direct wave.But along with the increase of space diversity dimension, the calculated amount of algorithm increases greatly, is unfavorable for the Project Realization of the method.

Summary of the invention

Technical matters to be solved by this invention is, a kind of external illuminators-based radar direct wave restoration methods is provided, the method, for the blind balance method of space diversity, devises the interval alternative manner that calculated amount is less, achieves the recovery of direct wave under strong multipath clutter environment.

In order to solve the problems of the technologies described above, the invention provides a kind of external illuminators-based radar direct wave restoration methods and comprising:

S101: the reference channel of external illuminators-based radar adopts space diversity method to receive the diversity signal of multiple diversity passage;

S102: the diversity signal for each diversity passage adopts a road balanced device to process, thus obtains multichannel equalizer output signal; Wherein, in formula, p _ik () represents the i-th road equalizer output signal, x _ik () represents the diversity signal of current time i-th diversity passage, f _ik () is N _f× 1 vector, represents the vector of No. i-th balanced device, f _i ^lk () represents l equalizer coefficients of No. i-th balanced device, $f_i\left(k\right)={\left[\begin{array}{cccccc}{f}_i^0\left(k\right)& f_i^1\left(k\right)& \mathrm{...}& f_i^l\left(k\right)& \mathrm{...}& f_i^{N_f-1}\left(k\right)\end{array}\right]}^T,$ I=0,1 ..., N-1, N represent the number of balanced device;

S103: multichannel equalizer output signal is sued for peace, obtains direct-path signal; Wherein, z (k) represents direct-path signal;

S104: calculate error term according to described direct-path signal; Wherein, e (k)=z (k) [γ-z ²(k)], in formula, e (k) represents error term, and γ represents the kurtosis of the original signal a (k) that external illuminators-based radar is launched, and $\mathrm{\γ}=\frac{E\left\{\right|a\left(k\right){|}^4\}}{E\left\{\right|a\left(k\right){|}^2\}};$

S105: calculate square error according to described error term, and judge whether described square error is less than pre-determined threshold; Wherein, described square error is σ ²(k+1)=λ σ ²(k)+e (k) e ^*k (), in formula, λ is forgetting factor, initial value σ ²(0)=0;

S106: if described square error is not less than described pre-determined threshold, then return S104 and calculate next error term e (k+1);

S107: if described square error is less than described pre-determined threshold, then every N _gindividual sampled point, carries out iteration to the vector of each road balanced device; Wherein, vectorial iterative formula is f _i(k+1)=f _i(k)+μ X _i ^*(k) e (k), in formula, X _i(k)=[x _i(k) x _i(k-1) ... x _i(k-l) ... x _i(k-N _f+ 1)] ^t, X _ik () represents the input vector of i-th diversity passage, x _i(k-l) represent l diversity signal of i-th diversity passage, μ is step factor.

Implement the present invention, there is following beneficial effect: external illuminators-based radar direct wave restoration methods of the present invention is for the blind balance method of space diversity, devise the interval alternative manner that calculated amount is less, achieve the recovery of direct wave under strong multipath clutter environment, be easy to Project Realization.

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 is the schematic flow sheet of an embodiment of external illuminators-based radar direct wave restoration methods provided by the invention;

Fig. 2 is the theory diagram of Fig. 1;

Fig. 3 is the schematic flow sheet of the emulation verification method to external illuminators-based radar direct wave restoration methods provided by the invention;

Fig. 4 is the theory diagram of Fig. 3;

Fig. 5 is the theory diagram of S201;

Fig. 6 is SD-CMA algorithm output signal modulus value;

Fig. 7 is the schematic diagram of SD-CMA algorithm range Doppler plane;

Fig. 8 be spaced apart 2 IISD-CMA algorithm output signal modulus value;

Fig. 9 is the range Doppler figure of the IISD-CMA algorithm being spaced apart 2

Figure 10 be spaced apart 3 IISD-CMA algorithm output signal modulus value;

Figure 11 is the range Doppler figure of the IISD-CMA algorithm being spaced apart 3.

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.

Fig. 1 is the schematic flow sheet of an embodiment of external illuminators-based radar direct wave restoration methods provided by the invention, and Fig. 2 is the theory diagram of Fig. 1, as depicted in figs. 1 and 2, comprising:

S101: the reference channel of external illuminators-based radar adopts space diversity method to receive the diversity signal of multiple diversity passage;

S102: the diversity signal for each diversity passage adopts a road balanced device to process, thus obtains multichannel equalizer output signal; Wherein, in formula, p _ik () represents the i-th road equalizer output signal, x _ik () represents the diversity signal of current time i-th diversity passage, f _ik () is N _f× 1 vector, represents the vector of No. i-th balanced device, f _i ^lk () represents l equalizer coefficients of No. i-th balanced device, $f_i\left(k\right)={\left[\begin{array}{cccccc}{f}_i^0\left(k\right)& f_i^1\left(k\right)& \mathrm{...}& f_i^l\left(k\right)& \mathrm{...}& f_i^{N_f-1}\left(k\right)\end{array}\right]}^T,$ I=0,1 ..., N-1, N represent the number of balanced device;

S103: multichannel equalizer output signal is sued for peace, obtains direct-path signal; Wherein, z (k) represents direct-path signal;

S104: calculate error term according to described direct-path signal; Wherein, e (k)=z (k) [γ-z ²(k)], in formula, e (k) represents error term, and γ represents the kurtosis of the original signal a (k) that external illuminators-based radar is launched, and $\mathrm{\γ}=\frac{E\left\{\right|a\left(k\right){|}^4\}}{E\left\{\right|a\left(k\right){|}^2\}};$

S105: calculate square error according to described error term, and judge whether described square error is less than pre-determined threshold; Wherein, described square error is σ ²(k+1)=λ σ ²(k)+e (k) e ^*k (), in formula, λ is forgetting factor, initial value σ ²(0)=0;

S106: if described square error is not less than described pre-determined threshold, then return S104 and calculate next error term e (k+1);

S107: if described square error is less than described pre-determined threshold, then every N _gindividual sampled point, carries out iteration to the vector of each road balanced device; Wherein, vectorial iterative formula is f _i(k+1)=f _i(k)+μ X _i ^*(k) e (k), in formula, X _i(k)=[x _i(k) x _i(k-1) ... x _i(k-l) ... x _i(k-N _f+ 1)] ^t, X _ik () represents the input vector of i-th diversity passage, x _i(k-l) represent l diversity signal of i-th diversity passage, μ is step factor.

Correctness below by the Computer Simulation signal authentication embodiment of the present invention:

As shown in Figure 3 and Figure 4, the step of emulation verification method comprises:

S201: original signal is sent to multiple diversity passage by space diversity method by external illuminators-based radar.

Concrete, as shown in Figure 5, described S201 specifically comprises:

Original signal is sent to multiple diversity passage by space diversity method by external illuminators-based radar, and wherein, the diversity signal on i-th diversity passage is in formula, the original signal that a (k) launches for external illuminators-based radar, n _ik () is the noise of i-th diversity channel reception end, h _ik () is L _r× 1 channel response vector, and $h_i\left(k\right)={\left[\begin{array}{cccccc}{h}_i^0\left(k\right)& h_i^1\left(k\right)& \mathrm{...}& h_i^l\left(k\right)& \mathrm{...}& h_i^{L_r-1}\left(k\right)\end{array}\right]}^T,$ represent i-th diversity passage l channel coefficients.

S202: adopt external illuminators-based radar direct wave restoration methods provided by the invention to recover direct-path signal.

S203: adopt least mean square algorithm to carry out clutter cancellation according to monitoring channel signal and described direct-path signal, obtain the signal after offseting.

Concrete, described S203 specifically comprises:

Produce monitoring channel signal y (k), wherein, in formula, n _sk () is receiver noise, c is multipath clutter, and l _sfor multipath number, g (k) is target echo signal, and f _dmfor bistatic Doppler, ξ is bistatic time delay, f _sfor sample frequency, M _tfor target number;

Carry out auto adapted filtering to described direct-path signal, wherein, wave filter input recursive vector is Z (k)=[z (k) z (k-1) ... z (k-l) ... z (k-N _w+ 1)] ^t, in formula, z (k-l) is the input recurrence direct-path signal of l time delay;

Adopt least mean square algorithm to carry out clutter cancellation, obtain signal u (k) after offseting, wherein, u (k)=y (k)-Z ^hk () V (k), in formula $V\left(k\right)={\left[\begin{array}{cccccc}{v}_0\left(k\right)& v_1\left(k\right)& \mathrm{...}& v_l\left(k\right)& \mathrm{...}& v_{N_w-1}\left(k\right)\end{array}\right]}^T$ For weight vector, v _lk () is l weighting coefficient, weight vector iterative formula is V (k+1)=V (k)+η Z (k) u ^*k (), η is step factor.

S204: build range Doppler plane according to the signal after described suppression.

Concrete, described S204 specifically comprises:

Build range Doppler plane according to the signal after described suppression, wherein, described range Doppler plane is: n _cfor persistence length, ξ represents time delay, and m represents Doppler shift.

S205: by target location, described range Doppler plane monitoring-network place.

Wherein, simulation parameter is specially: system bandwidth is 100kHz, and data transfer rate is 200kHz.Arranging integral time length is 2s.Balanced device weight vector length is set to 41, and iteration step length is that the bistatic time delay of 0.001, two targets and Doppler are respectively (171km ,-300Hz), (276km, 60Hz).Clutter noise ratio is-58dB, and signal to noise ratio (S/N ratio) (SNR) is set to-3dB.Be set to 20 as the least mean square algorithm offseted (LMS algorithm) weight vector length, iteration step length is set to 0.001.Space diversity dimension is set to 3, reference channel is provided with 3 points of diversity sub-channels, is shown in Table 1, by method of the present invention, namely interval iteration space diversity constant mould blind balance method is designated as IISD-CMA, and Conventional spatial diversity constant mould blind balance method is designated as SD-CMA.。Non-vanishing channel tap coefficient is listed in table 1.The channel multipath coefficient of monitoring channel is in the channel c in table 1.

Table 1 emulates 15 three footpath channels used

Emulation main contrast SD-CMA compares with the speed of convergence in direct wave rejuvenation, range Doppler plane monitoring-network performance etc. of IISD-CMA method.SD-CMA method constringency performance is shown in Fig. 6.Modulus value is tending towards constant and shows that algorithm has successfully recovered the frequency modulation broadcasting reference signal that modulus value is constant.The fluctuating of modulus value indicates speed of convergence from large to small.The target detection performance of range Doppler plane is shown in Fig. 7, and two targets are high-visible.

Iteration interval gets the constringency performance of the IISD-CMA method of 2 as shown in Figure 8, and calculated amount comparatively declines 2 times without interval arithmetic.The speed of convergence of visible the method does not obviously decline.The target detection performance of range Doppler plane is shown in Fig. 9, and visible two targets corresponding with the SD-CMA method of Fig. 5 are high-visible, and signal to noise ratio (S/N ratio) is close.

Change the interval of interval alternative manner, get and be spaced apart 3, calculated amount comparatively declines 3 times without interval arithmetic.Algorithm output signal modulus value change curve is shown in Figure 10.Compared with Fig. 6, speed of convergence slightly declines.Target detection performance is shown in Figure 11, loses without significant performance.

Implement the present invention, there is following beneficial effect: external illuminators-based radar direct wave restoration methods provided by the invention is for the blind balance method of space diversity, devise the interval alternative manner that calculated amount is less, achieve the recovery of direct wave under strong multipath clutter environment, be easy to Project Realization.

It should be noted that, in this article, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thus make to comprise the process of a series of key element, method, article or device and not only comprise those key elements, but also comprise other key elements clearly do not listed, or also comprise by the intrinsic key element of this process, method, article or device.When not more restrictions, the key element limited by statement " comprising ... ", and be not precluded within process, method, article or the device comprising this key element and also there is other identical element.

In several embodiments that the application provides, should be understood that, disclosed system and method can realize by another way.Such as, system embodiment described above is only schematic, such as, the division of described unit, be only a kind of logic function to divide, actual can have other dividing mode when realizing, such as multiple unit or assembly can in conjunction with or another system can be integrated into, or some features can be ignored, or do not perform.Another point, shown or discussed coupling each other or direct-coupling or communication connection can be by some interfaces, and the indirect coupling of device or unit or communication connection can be electrical, machinery or other form.

Professional can also recognize further, in conjunction with unit and the algorithm steps of each example of embodiment disclosed herein description, can realize with electronic hardware, computer software or the combination of the two, in order to the interchangeability of hardware and software is clearly described, generally describe composition and the step of each example in the above description according to function.These functions perform with hardware or software mode actually, depend on application-specific and the design constraint of technical scheme.Professional and technical personnel can use distinct methods to realize described function to each specifically should being used for, but this realization should not thought and exceeds scope of the present invention.

The software module that the method described in conjunction with embodiment disclosed herein or the step of algorithm can directly use hardware, processor to perform, or the combination of the two is implemented.Software module can be placed in the storage medium of other form any known in random access memory (RAM), internal memory, ROM (read-only memory) (ROM), electrically programmable ROM, electrically erasable ROM, register, hard disk, moveable magnetic disc, CD-ROM or technical field.

To the above-mentioned explanation of the disclosed embodiments, professional and technical personnel in the field are realized or uses the present invention.To be apparent for those skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein can without departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.

Claims (1)

1. an external illuminators-based radar direct wave restoration methods, is characterized in that, comprising:

S101: the reference channel of external illuminators-based radar adopts space diversity method to receive the diversity signal of multiple diversity passage;

S102: the diversity signal for each diversity passage adopts a road balanced device to process, thus obtains multichannel equalizer output signal; Wherein, in formula, p _ik () represents the i-th road equalizer output signal, x _ik () represents the diversity signal of current time i-th diversity passage, f _ik () is N _f× 1 vector, represents the vector of No. i-th balanced device, f _i ^lk () represents l equalizer coefficients of No. i-th balanced device, $f_i\left(k\right)={\left[\begin{array}{cccccc}{f}_i^0\left(k\right)& f_i^1\left(k\right)& \mathrm{...}& f_i^l\left(k\right)& \mathrm{...}& f_i^{N_f-1}\left(k\right)\end{array}\right]}^T,i=0,1,\mathrm{...},N-1,$ N represents the number of balanced device;

S103: multichannel equalizer output signal is sued for peace, obtains direct-path signal; Wherein, $z\left(k\right)=\frac{1}{N}\underset{i=0}{\overset{N-1}{\Σ}}{p}_i\left(k\right),$ Z (k) represents direct-path signal;

S104: calculate error term according to described direct-path signal; Wherein, e (k)=z (k) [γ-z ²(k)], in formula, e (k) represents error term, and γ represents the kurtosis of the original signal a (k) that external illuminators-based radar is launched, and $\mathrm{\γ}=\frac{E\left\{\right|a\left(k\right){|}^4\}}{E\left\{\right|a\left(k\right){|}^2\}};$

S105: calculate square error according to described error term, and judge whether described square error is less than pre-determined threshold; Wherein, described square error is σ ²(k+1)=λ σ ²(k)+e (k) e ^*k (), in formula, λ is forgetting factor, initial value σ ²(0)=0;

S106: if described square error is not less than described pre-determined threshold, then return S104 and calculate next error term e (k+1);

S107: if described square error is less than described pre-determined threshold, then every N _gindividual sampled point, carries out iteration to the vector of each road balanced device; Wherein, vectorial iterative formula is f _i(k+1)=f _i(k)+μ X _i ^*(k) e (k), in formula, X _i(k)=[x _i(k) x _i(k-1) ... x _i(k-l) ... x _i(k-N _f+ 1)] ^t, X _ik () represents the input vector of i-th diversity passage, x _i(k-l) represent l diversity signal of i-th diversity passage, μ is step factor.