CN104122548B - Meter wave array radar angle-measuring method swept by machine - Google Patents

Abstract

The invention discloses a kind of machine and sweep the angle-measuring method of meter wave array radar, the problem that meter wave array radar angle measurement accuracy is low swept by the machine that mainly solves, and implementation step is: 1. by the pulse echo signal of antenna array receiver radar；2. calculate the search weight vector of all pulses；3., with any one pulse as reference pulse, the search weight vector of other pulse is compensated；4. the search weight vector after utilizing pulse echo signal and compensating builds a cost function；5. pair cost function carries out beam scanning, obtains the off-axis angle of target；6. the off-axis angle of target is added with the reference angle of reference pulse, obtains the precise angle of target.It is little that the present invention has angle error, and precision is high, the advantage that robustness is good, can be used for machine and sweeps meter wave array radar and be accurately positioned target and target following.

Description

Meter wave array radar angle-measuring method swept by machine

Technical field

The invention belongs to Radar Technology field, particularly to radar angle measurement method, can be used for machine and sweep metric wave array thunder Reach angle measurement, can be used for target following and altitude measurement in VHF radar.

Background technology

Metre wave radar is little due to signal attenuation, and detection range is remote, at the aspect such as over-the-horizon detection, Anti-amyloid-β antibody There is the advantage of uniqueness, but simultaneously because the wavelength of metre wave radar is longer, wave beam is wider so that it is angle-resolved Rate variance, angle measurement accuracy is low.Mechanical scanning radar is due to low cost, it is achieved the factor such as simple is always extensive by people Application.Mechanic scan radar angle-measuring method typically uses maximum-signal method, but the precision of this method is poor, especially Metre wave radar is swept for machine.Owing to its electricity size is less, wave beam is wider, and maximum-signal method angle measurement accuracy is the highest.

Society generally requires radar and has multi-functional characteristic now.In order to meet this demand, metre wave radar swept by machine In occurred as soon as machine sweep power up the azimuth dimension of the mode swept, i.e. radar antenna not only can be with mechanical scanning but also can sweep by electricity Retouch.At this moment radar antenna often uses array antenna, and is digital beam froming system.Here it is so-called machine Sweep meter wave array radar.

Fourth aigret flies to teach to be given in " Principles of Radar [M], publishing house of Xian Electronics Science and Technology University, 2002 " book Go out digital beam forming technology.Digital beam forming technology refers to utilize the aperture of array antenna, by numeral Signal processing is formed in desired direction and receives wave beam.Sampled data is made weighted sum, can be weighed by change Value so that the direction that beam position is different, and realize the scanning of wave beam.Meter wave array radar is swept for this machine Conventional angle-measuring method is first to be utilized digital beam scan method to measure target and antenna method by individual pulse signal The off-axis angle in line direction, adds now antenna normal direction and the angle of direct north, obtains individual pulse and survey The angle on target obtained, it is exactly angle on target that the angle recording all pulses is averaged.

Although meter wave array radar swept by machine is that machine is swept and powered up the mode swept, meet the multi-functional demand of radar, but The feature not having fully utilized array antenna and mechanical scanning to combine when using conventional angle-measuring method angle measurement, makes The machine of obtaining is swept meter wave array radar and cannot be made full use of the resource of arrayed multi-channel and mechanical scanning when mechanical scanning, Cause its angle error big, the defect that angle measurement accuracy is the lowest.

Summary of the invention

Present invention aims to above-mentioned machine and sweep the deficiency of meter wave array radar routine angle-measuring method, carry Go out a kind of machine and sweep meter wave array radar angle-measuring method, to reduce the noise impact on signal, reduce angle error, Improve angle measurement accuracy.

The technical scheme is that for achieving the above object and to be achieved in that:

One, technical thought

Compensated by search weight vector when machine is swept the scanning of meter wave array radar digital beam, radar is sent out The multiple impulse compensations penetrated are to same position.Utilize the search weight vector after compensating and echo-signal, set up one Cost function on the basis of the off-axis angle of some pulse, carries out beam scanning to this cost function and obtains target Off-axis angle, the reference angle utilizing the off-axis angle of target corresponding obtains the real angle of target.

Two, step is realized

According to above-mentioned technical thought, the step that realizes of the present invention includes the following:

(1), during antenna scanning, a pulse is launched at interval of Δ θ, and when will launch i-th pulse, antenna The angle of centre normal and horizontal reference plane is as reference angleI=1,2 ..., L, L are at a wave beam The pulse number launched altogether in width, Δ θ is the interval of adjacent two pulses；

(2) meter wave array radar antenna swept by the machine that sets N number of array element, utilizes this N number of array element to receive echo-signal, Obtain echo-signal X of i-th pulse_i；

(3) search angle ψ is set near the antenna normal direction of i-th pulse, according to search angle ψ Calculate search weight vector w_i(ψ):

w_i(ψ)=[1, exp (j2 π dsin ψ/λ) ..., exp (j2 π (N-1) dsin ψ/λ)]^T,

Wherein, the span of search angle ψ is more than half-power beam width, and exp represents the index with e as the end Power, d is antenna spacing, and λ is signal wavelength, []^TRepresent the non-conjugated transposition of vector；

(4) with first pulse for reference pulse to weight vector w_i(ψ) compensate, be compensated rear i-th The weight vector of individual pulse is w_i(ψ+(i-1)Δθ)；

(5) according to echo-signal X received_iWith the weight vector w after compensation_i(ψ+(i-1) Δ θ), builds Cost function P (ψ):

$P\left(\mathrm{\ψ}\right)=\left|X_1^{H}w\left(\mathrm{\ψ}\right)\right|+\left|X_2^{H}w(\mathrm{\ψ}+\mathrm{\Δ\θ})\right|+...+\left|X_L^{H}w(\mathrm{\ψ}+(L-1)\mathrm{\Δ\θ})\right|,$ Its In, i=1,2 ..., L, | | represent delivery value, []^HRepresent conjugate transpose；

(6) in the range of search angle ψ, cost function P (ψ) is carried out beam scanning, obtain target and sending out Penetrate off-axis angle θ during first pulse₁, by off-axis angle θ₁Reference angle with first pulseIt is added, obtains The precise angle Φ of target, wherein

The present invention compared with prior art has the advantage that

1) angle measurement accuracy is high

Output data after carrying out beam scanning due to each pulse have a maximum, and this maximum is corresponding Angle be exactly the off-axis angle of target, conventional method is only that the angle measurement result to each pulse is accumulated, Be equivalent to binary integration, cause snr loss, angle measurement accuracy to decrease.And due to the fact that and power is vowed Amount is compensated, and constructs a cost function, is equivalent to all of pulse scanning function has been carried out non-phase Ginseng accumulation, increases signal to noise ratio, thus improves angle measurement accuracy.

2) operand is little

Conventional angle-measuring method is that each pulse needs survey to be scanned angle measurement, is averaging the most again.The present invention be by Carry out angle measurement after all pulse weighted sums again, only need run-down just can obtain angle on target, decrease computing Amount.

Accompanying drawing explanation

Fig. 1 is the flowchart of the present invention；

Fig. 2 is with the present invention and the tradition beam sweeping method mean square error comparison diagram when antenna alignment；

Fig. 3 is with the present invention and the tradition beam sweeping method mean square error comparison diagram when antenna misalignments.

Detailed description of the invention

With reference to Fig. 1, the present invention to be embodied as step as follows:

Step 1, meter wave array radar antenna model swept by structure machine.

If machine sweeps the uniform line-array that the antenna of meter wave array radar is made up of, i.e. any two phase N number of array element Array element distance d between adjacent array element is the most equal, and launches the half of the wavelength X of signal for metre wave radar, D=λ/2.

Step 2, utilizes machine to sweep meter wave array radar and launches pulse signal.

Machine sweeps meter wave array radar with horizontal plane for reference to angle 0 °, and machine sweeps meter wave array radar in antenna scanning Time, launch a pulse at interval of Δ θ, and when will launch i-th pulse, center of antenna normal is joined with level Examine the angle in face as reference angleI=1,2 ..., L, L are the arteries and veins launched altogether in a beam angle Rushing number, Δ θ is the interval of adjacent two pulses.

Step 3, receives pulse echo signal.

The machine described in step 1 is utilized to sweep L pulse described in metre wave radar antenna model receiving step 2, Obtain echo-signal X of i-th pulse_i: X_i=S_i×a(θ_i)+n_i,

Wherein, S_iRepresent the complex envelope information of i-th pulse signal,s₀For just Beginning complex amplitude, j represents imaginary unit, f_dRepresent the Doppler frequency of target,V represents Target is relative to the radial velocity of radar, f₀Representing the mid frequency of radar transmitted pulse signal, c represents light Speed, t represents the sampling interval；

a(θ_i) it is the steering vector of i-th pulse:

a(θ_i)=[1, exp (j2 π dsin θ_i/λ),...,exp(j2π(N-1)dsinθ_i/λ)]^T, θ_iRepresent target Relative to the angle between antenna normal, referred to as off-axis angle, exp represents the exponential depth with e as the end, d generation Table array element distance, λ representation signal wavelength, []^TRepresent the non-conjugated transposition of vector；

n_iRank, the N × 1 white Gaussian noise matrix that the average of expression i-th reception of impulse is 0, variance is 1.

Step 4, calculates search weight vector w_i(ψ)。

Search angle ψ is set near the antenna normal direction of i-th pulse, calculates according to search angle ψ and search Rope weight vector w_i(ψ):

w_i(ψ)=[1, exp (j2 π dsin ψ/λ) ..., exp (j2 π (N-1) dsin ψ/λ)]^T, wherein, angle of aspect The span of degree ψ is more than half-power beam width, and j represents imaginary unit, and d represents array element distance, λ Representation signal wavelength, N is element number of array.

Step 5, to the weight vector w described in step 4_i(ψ) compensate.

5a) determine weight vector w_i(ψ) offset: with first pulse as reference, being compensated value is one Individual initial value is 0, and difference is the arithmetic progression of Δ θ, i.e. the offset of other pulse weight vector is followed successively by 0,Δθ,2Δθ,...,(i-1)Δθ；

5b) the weight vector w to i-th pulse_i(ψ) compensate: with first pulse as reference, by step 5a) obtain offset (i-1) the Δ θ of i-th pulse, it is added, after being compensated with former search angle ψ Search angle ψ+(i-1) Δ θ, will compensate after search angle bring weight vector w into_i(ψ), i-th is obtained Weight vector w after impulse compensation_i(ψ+(i-1)Δθ)。

Step 6, by echo-signal X described in step 3_iWith the weight vector after the compensation described in step 5 w_i(ψ+(i-1) Δ θ) builds vertical cost function P (ψ).

6a) calculate search modulus value P after the compensation authority vector of each pulse_i(ψ):

Wherein, i=1,2 ..., L, | | represent delivery value, [·]^HRepresent conjugate transpose；

6b) by search modulus value P of each pulse_i(ψ) it is added, obtains cost function P (ψ):

$P\left(\mathrm{\ψ}\right)=\underset{i}{\overset{L}{\mathrm{\Σ}}}{P}_i\left(\mathrm{\ψ}\right)=\left|X_1^{H}w\left(\mathrm{\ψ}\right)\right|+\left|X_2^{H}w(\mathrm{\ψ}+\mathrm{\Δ\θ})\right|+...+\left|X_L^{H}w(\mathrm{\ψ}+(L-1)\mathrm{\Δ\θ})\right|.$

Step 7, carries out beam scanning to cost function P (ψ), measures the off-axis angle of target.

In the range of search angle ψ, cost function P (ψ) is carried out beam scanning, obtain beam scanning maximum Corresponding angle, i.e. in off-axis angle θ of first pulse position target₁。

Step 8, calculates the precise angle of target.

By off-axis angle θ first pulse position target₁Reference angle with first pulseIt is added, obtains The precise angle Φ of target, wherein

The effect of the present invention can be verified by machine calculated below emulation:

One, simulated conditions

Simulated conditions 1,

If machine sweeps the uniform line-array that the antenna of meter wave array radar is made up of, the beam angle of antenna 8 array elements Being about 12 °, antenna carries out rotation sweep with the speed of 10s/r, and radar is launched a frequency every 3ms and is The pulse of 300MHz, antenna receives 25 pulse signals every time.Assume that antenna normal is directed at target, mesh Target real angle is 10 °, and target is 50m/s relative to the radial velocity of radar, and its Doppler frequency can be counted Calculation obtains as 100Hz.Array scanning angular range is-20 ° to 40 °, and signal to noise ratio takes-5dB to 10dB, carries out 500 Monte Carlo Experiments.

Simulated conditions 2,

If machine sweeps the uniform line-array that the antenna of meter wave array radar is made up of, the beam angle of antenna 8 array elements Being about 12 °, antenna carries out rotation sweep with the speed of 10s/r, and radar is launched a frequency every 3ms and is The pulse of 300MHz, antenna receives 25 pulse signals every time.Assume antenna normal misalignment target, Center of antenna deviation 4 pulses of target.The real angle of target is 10 °, and target is relative to the radial velocity of radar For 50m/s, its Doppler frequency can be calculated as 100Hz.Array scanning angular range is-20 ° to 40 °, Signal to noise ratio takes-5dB to 10dB, carries out 500 Monte Carlo Experiments.

Two, emulate content

Emulation 1, utilizes simulated conditions 1 that target uses the present invention and conventional beam sweeping method survey respectively Angle, the root-mean-square error curve that available two kinds of methods change with signal to noise ratio.As in figure 2 it is shown, horizontal seat in Fig. 2 Being designated as signal to noise ratio, unit is dB, and vertical coordinate is root-mean-square error, and unit is degree.

During from Figure 2 it can be seen that cardiac wave bundle is to quasi goal in antennas, the present invention is than conventional beam scanning algorithm essence Degree wants height, and particularly when signal to noise ratio is low, effect is clearly.Show that the present invention can reduce effect of noise, Improve angle measurement accuracy.

Emulation 2, utilizes simulated conditions 2 that target uses the present invention and conventional beam sweeping method survey respectively Angle, the root-mean-square error curve of available two kinds of methods, as it is shown on figure 3, abscissa is signal to noise ratio in Fig. 3, Unit is dB, and vertical coordinate is root-mean-square error, and unit is degree.

As seen from Figure 3, in antennas cardiac wave bundle misalignment target time the present invention angle measurement accuracy still ratio conventional Beam scanning arithmetic accuracy is high, and effect is clearly.Fig. 3 explanation present invention when antenna misalignments target depends on So can reduce effect of noise, improve angle measurement accuracy.

From the contrast of Fig. 3 Yu Fig. 2, during the inventive method cardiac wave bundle misalignment in antennas and antenna alignment Time angle measurement accuracy almost do not change, it is seen that the present invention as conventional beam sweeping method all to antenna The most insensitive to quasi goal.

Claims (4)

1. a meter wave array radar angle-measuring method swept by machine, comprises the steps:

(1), during antenna scanning, a pulse is launched at interval of Δ θ, and when will launch i-th pulse, center of antenna The angle of normal and horizontal reference plane is as reference angleI=1,2 ..., L, L are to send out altogether in a beam angle The pulse number penetrated, Δ θ is the interval of adjacent two pulses；

(2) machine that sets sweeps the uniform line-array that meter wave array radar antenna is made up of, the most any two adjacent battle arrays N number of array element Array element distance d between unit is the most equal, and launches the half of the wavelength X of signal for metre wave radar, d=λ/2, profit Receive echo-signal by this N number of array element, obtain echo-signal X of i-th pulse_i；

(3) search angle ψ is set near the antenna normal direction of i-th pulse, calculates according to search angle ψ Search weight vector w_i(ψ):

w_i(ψ)=[1, exp (j2 π dsin ψ/λ) ..., exp (j2 π (N-1) dsin ψ/λ)]^T,

Wherein, the span of search angle ψ is more than half-power beam width, and exp represents the exponential depth with e as the end, d For antenna spacing, λ is signal wavelength, []^TRepresent the non-conjugated transposition of vector；

(4) with first pulse for reference pulse to weight vector w_i(ψ) compensate, be compensated rear i-th pulse Weight vector be w_i(ψ+(i-1)Δθ)；

(5) according to echo-signal X received_iWith the weight vector w after compensation_i(ψ+(i-1) Δ θ), builds cost letter Number P (ψ):

Wherein, I=1,2 ..., L, | | represent delivery value, []^HRepresent conjugate transpose；

(6) in the range of search angle ψ, cost function P (ψ) is carried out beam scanning, obtain target and launching first Off-axis angle θ during individual pulse₁, by off-axis angle θ₁Reference angle with first pulseIt is added, obtains the accurate angle of target Degree Φ, wherein

Meter wave array radar angle-measuring method swept by machine the most according to claim 1, it is characterised in that described step (2) Echo-signal X of i-th pulse_i, its expression is:

X_i=S_i×a(θ_i)+n_i, i=1,2 ..., L,

Wherein, S_iRepresent the complex envelope information of i-th pulse signal,s₀For initial complex amplitude, j Represent imaginary unit, f_dRepresent the Doppler frequency of target,V represents the target footpath relative to radar To speed, f₀Representing the mid frequency of radar emission signal, c represents the light velocity, and t represents the sampling interval；

a(θ_i) it is the steering vector of i-th pulse:

a(θ_i)=[1, exp (j2 π dsin θ_i/λ),...,exp(j2π(N-1)dsinθ_i/λ)]^T, θ_iRepresent target relative to Angle between antenna normal, referred to as off-axis angle, exp represents the exponential depth with e as the end, and d represents array element distance, λ Representation signal wavelength, []^TRepresent the non-conjugated transposition of vector；

n_iRank, the N × 1 white Gaussian noise matrix that the average of expression i-th reception of impulse is 0, variance is 1.

Meter wave array radar angle-measuring method swept by machine the most according to claim 1, it is characterised in that described step (4) In with first pulse for reference pulse to weight vector w_i(ψ) compensate, carry out as follows:

4a) determine the offset of weight vector: with first pulse as reference, be compensated value be an initial value be 0, Difference is the arithmetic progression of Δ θ, and the offset of i.e. every subpulse is followed successively by 0, Δ θ, 2 Δ θ ..., (i-1) Δ θ；

4b) weight vector is compensated: with first pulse as reference, utilize the offset obtained by each pulse Search weight vector is normalized to first pulse weight vector position, obtains the weight vector after i-th impulse compensation w_i(ψ+(i-1)Δθ)。

Meter wave array radar angle-measuring method swept by machine the most according to claim 1, it is characterised in that step (5) Described echo-signal X according to reception_iWith the weight vector w after compensation_i(ψ+(i-1) Δ θ), builds cost function P (ψ), is carried out as follows:

5a) calculate search modulus value P after the compensation authority vector of each pulse_i(ψ):

Wherein, i=1,2 ..., L, | | represent delivery value, []^HRepresent Conjugate transpose；

5b) by search modulus value P of each pulse_i(ψ) it is added, obtains cost function P (ψ):

$P\left(\mathrm{\ψ}\right)=\underset{i}{\overset{L}{\Σ}}{P}_i\left(\mathrm{\ψ}\right)=\left|X_1^{H}w\left(\mathrm{\ψ}\right)\right|+\left|X_2^{H}w(\mathrm{\ψ}+\mathrm{\Δ}\mathrm{\θ})\right|+...+\left|X_L^{H}w(\mathrm{\ψ}+(L-1\left)\mathrm{\Δ}\mathrm{\θ}\right)\right|.$