CN103018737B - Method for utilizing frequency distribution array (FDA) radar to estimate object distance and azimuthal angle and FDA radar - Google Patents

Abstract

The invention belongs to the technical field of frequency distribution array (FDA) radars and discloses a method for utilizing a frequency distribution array (FDA) radar to estimate an object distance and an azimuthal angle. The method comprises the steps of dividing transmitting array elements of the radar into a first transmitting subarray and a second transmitting subarray with equal array element numbers, generating transmitting signals of the two transmitting subarrays, and estimating the azimuthal angle of the distance of an object. According to the method, the distance dependence characteristics of FDA radar beam can be effectively utilized to perform joint estimation on the azimuthal angle of the distance of the object, and the coupled problem which occurs when the FDA radar is utilized to estimate the distance and the azimuthal angle of the object is solved.

Description

A kind of method and FDA radar with FDA radar estimating target distance and bearing angle

Technical field

The invention belongs to Radar Technology field, be specifically related to frequency diversity array (FDA) Radar Technology field.

Background technology

Phased-array radar can freely be realized the spacescan of wave beam, thereby is widely used in Radar Targets'Detection and imaging.Conventionally the each array element transmitting of phased-array radar is same signal, realizes beam direction control by the output terminal access phase shifter in each array element, and the phase-shift phase of adjusting phase shifter just can be realized the spatial domain scanning of wave beam.But phased-array radar is in each snap, beam position is constant on all Range resolutions unit, that is to say that beam position and distance have nothing to do, thereby can not utilize the two dimension at linear phase controlled array radar realize target distance and bearing angle to combine estimation.But in some applications, usually expect again that array beams can point to different distances with different angles in same snap, this just needs the sensing of wave beam to change with the variation of distance.

Frequency diversity array (FDA, Frequency Diverse Array) radar applies different frequency deviations to different array element at one time, Range-dependent beam scanning function can be provided, and this and traditional phased array and frequency scan antenna are all different; The frequency deviation of frequency scan antenna is to apply in the different time, and the frequency deviation of all array elements is identical; The coherent signal that FDA radar emission is the same with phased array, but each array element has been added different frequency deviation Δ f, thereby the signal frequency radiateing is different.

Prior art has been analyzed the Range-dependent characteristic of FDA radar beam, but do not answer and how to effectively utilize this Range-dependent characteristic, do not solve yet FDA radar to target range to the coupled problem when estimating with position angle, that is: launching beam can not focus on the impact point of expectation, but be scattered in a distance to upper to " the peak ridge " that be coupled with position angle, as shown in Figure 1.

Summary of the invention

For solve prior art with FDA radar to target range to the technical matters existing when estimating with position angle, the present invention proposes a kind of method with FDA radar estimating target distance and bearing angle, can effectively solve above-mentioned problems of the prior art.

In order to solve this technical matters, a first aspect of the present invention is to provide a kind of method with FDA radar estimating target distance and bearing angle, comprises the steps:

1) the transmitting array element of radar is divided into element number of array and equates the first transmitting subarray and the second transmitting subarray;

2) produce transmitting of two subarrays:

The frequency transmitting of the each array element in the first transmitting subarray is

f _c1，i＝f ₀+(i-1)·Δf ₁，i＝1，2，....M；

The frequency transmitting of the each array element in the second transmitting subarray is

f _c2，i＝f ₀+(i-1)·Δf ₂，i＝1，2，....M

M is the sum of array element in subarray, f ₀for radar system carrier frequency, Δ f ₁for the carrier frequency increment of predefined the first transmitting subarray, Δ f ₂for the carrier frequency increment of predefined the second transmitting subarray;

3) position angle of estimating target and distance:

$(\widehat{\mathrm{\θ}},\hat{r})=\underset{\mathrm{\θ},r}{\max }J(\mathrm{\θ},r)=\underset{\mathrm{\θ},r}{\max }{\left|w^H(\mathrm{\θ},r)y\right|}^2$

Wherein, w (θ, r) represents to receive the steering vector of signal, and θ is all possible position angle that receives signal beam, and r is all possible distance value that receives signal beam, and y is the signal receiving, () ^hrepresent conjugate transpose, for position angle and the distance of the target that estimates.

In order to solve this technical matters, combine with above-mentioned first aspect, a second aspect of the present invention is to provide a kind of method with FDA radar estimating target distance and bearing angle, in the time that the number of described transmitting array element is odd number,, taking the middle array element of array as mid point, array is divided into element number of array and equates the first transmitting subarray and the second transmitting subarray.

In order to solve this technical matters, combine with above-mentioned first aspect, a third aspect of the present invention is to provide a kind of method with FDA radar estimating target distance and bearing angle, the steering vector that the steering vector of described reception signal equals to transmit.

In order to solve this technical matters, combine with the above-mentioned third aspect, a fourth aspect of the present invention is to provide a kind of method with FDA radar estimating target distance and bearing angle, and the described steering vector transmitting is

$a(\mathrm{\θ},r)={[1,e^{-j{\mathrm{\ω}}_1},...e^{-j(M-1){\mathrm{\ω}}_1},1,e^{-j{\mathrm{\ω}}_2},...e^{-j(M-1){\mathrm{\ω}}_2}]}^T$

[] ^tfor vectorial transposition computing, ω ₁represent adjacent two phase differential that array element transmits in the first transmitting subarray, ω ₂represent adjacent two phase differential that array element transmits in the second transmitting subarray.

In order to solve this technical matters, combine with above-mentioned fourth aspect, a fifth aspect of the present invention is to provide a kind of method with FDA radar estimating target distance and bearing angle, described ω ₁and ω ₂calculated by following formula:

${\mathrm{\ω}}_1=\frac{2\mathrm{\π}{f}_{0}d\sin \mathrm{\θ}}{c_0}-\frac{2\mathrm{\π\Δ}{f}_{1}r}{c_0},$ ${\mathrm{\ω}}_2=\frac{2\mathrm{\π}{f}_{0}d\sin \mathrm{\θ}}{c_0}-\frac{2\mathrm{\π\Δ}{f}_{2}r}{c_0}$

Wherein, θ is all possible position angle that receives signal beam, and r is all possible distance value that receives signal beam, the spacing that d is adjacent array element, c ₀for the light velocity.

In order to solve this technical matters, combine with above-mentioned first aspect, a sixth aspect of the present invention is to provide a kind of method with FDA radar estimating target distance and bearing angle, described Δ f ₁with Δ f ₂obtaining value method be: wherein any one gets positive number, and another gets negative.

The present invention also provides a kind of new FDA radar, comprises the first transmitting subarray and the second transmitting subarray, and the frequency transmitting of the each array element in the first described transmitting subarray is:

f _c1，i＝f ₀+(i-1)·Δf ₁，i＝1，2，....M；

The frequency transmitting of the each array element in the second transmitting subarray is:

f _c2，i＝f ₀+(i-1)·Δf ₂，i＝1，2，....M；

M is the sum of array element in subarray, f ₀for radar system carrier frequency, Δ f ₁for the carrier frequency increment of predefined the first transmitting subarray, Δ f ₂for the carrier frequency increment of predefined the second transmitting subarray.

Useful technique effect of the present invention is:

1, can effectively utilize the Range-dependent characteristic of FDA radar beam, the position angle to target and distance are combined estimation;

2, overcome FDA radar to target range to the coupled problem existing when estimating with position angle.

Brief description of the drawings

Fig. 1 is the send-receive beam radiation figure of existing FDA radar;

Fig. 2 is the send-receive beam radiation figure of the FDA radar that proposes of the present invention;

Fig. 3 is the overview flow chart of a kind of method with FDA radar estimating target distance and bearing angle of proposing of the present invention;

Fig. 4 is the Δ f of the FDA radar that proposes of the present invention ₁with Δ f ₂performance comparison figure to target range and position angle estimation while getting different value.

Embodiment

Illustrate the embodiment of technical solution of the present invention below in conjunction with accompanying drawing.

This embodiment is taking an X-band FDA radar as example, its carrier frequency f ₀=10Hz, frequency deviation Δ f ₁=30kHz, Δ f ₂=10kHz.Suppose that a uniform linear array has 10 transmittings array elements and 10 to receive array elements, between array element, be spaced apart half wavelength (λ=c ₀/ f ₀), target is positioned at azimuth angle theta=10 ° and apart from r=10km.

As shown in Figure 3, a kind of method with FDA radar estimating target distance and bearing angle that the present invention proposes comprises the steps:

1) the transmitting array element of radar is divided into element number of array and equates the first transmitting subarray and the second transmitting subarray, in the time that the number of described transmitting array element is odd number,, taking the middle array element of array as mid point, array is divided into element number of array and equates the first transmitting subarray and the second transmitting subarray;

2) produce transmitting of two transmitting subarrays:

The frequency transmitting of the each array element in the first transmitting subarray is

f _c1，i＝f ₀+(i-1)·Δf ₁，i＝1，2，....M；

The frequency transmitting of the each array element in the second transmitting subarray is:

f _c2，i＝f ₀+(i-1)·Δf ₂，i＝1，2，....M

M is the sum of array element in subarray, f ₀for radar system carrier frequency, Δ f ₁for the carrier frequency increment of predefined the first transmitting subarray, Δ f ₂for the carrier frequency increment of predefined the second transmitting subarray;

3) position angle of estimating target and distance:

$(\widehat{\mathrm{\θ}},\hat{r})=\underset{\mathrm{\θ},r}{\max }J(\mathrm{\θ},r)=\underset{\mathrm{\θ},r}{\max }{\left|w^H(\mathrm{\θ},r)y\right|}^2$

Wherein, w (θ, r) represents to receive the steering vector of signal, and θ is all possible position angle that receives signal beam, and r is all possible distance value that receives signal beam, and y is the signal receiving, () ^hrepresent conjugate transpose, for position angle and the distance of the target that estimates.

Receives the steering vector w (θ, r) of signal and can think the steering vector that equals to transmit, and the steering vector transmitting is:

$a(\mathrm{\θ},r)={[1,e^{-j{\mathrm{\ω}}_1},...e^{-j(M-1){\mathrm{\ω}}_1},1,e^{-j{\mathrm{\ω}}_2},...e^{-j(M-1){\mathrm{\ω}}_2}]}^T$

Wherein, [] ^trepresent vectorial transposition computing, ω ₁represent adjacent two phase differential that array element transmits in the first transmitting subarray, ω ₂represent adjacent two phase differential that array element transmits in the second transmitting subarray.In order to reduce operand, ω ₁and ω ₂what can be similar to is calculated by following formula:

${\mathrm{\ω}}_1=\frac{2\mathrm{\π}{f}_{0}d\sin \mathrm{\θ}}{c_0}-\frac{2\mathrm{\π\Δ}{f}_{1}r}{c_0},$ ${\mathrm{\ω}}_2=\frac{2\mathrm{\π}{f}_{0}d\sin \mathrm{\θ}}{c_0}-\frac{2\mathrm{\π\Δ}{f}_{2}r}{c_0}$

Wherein, θ is all possible position angle that receives signal beam, and r is all possible distance value that receives signal beam, the spacing that d is adjacent array element, c ₀for the light velocity.

Fig. 4 has shown the Δ f of the FDA radar that the present invention proposes under different signal to noise ratio (S/N ratio)s (transverse axis represents) condition ₁with Δ f ₂while getting some groups of different values, the evaluated error that adopts this method to estimate target range and position angle (longitudinal axis represents), this evaluated error refers to the estimation variance of estimating always to target range and position angle, is to calculate respectively target range and position angle CramerRao lower limit CRB _rand cRB _θafter obtain, that is: can find out according to the variance of obtaining, as the Δ f of FDA radar ₁with Δ f ₂in any one get positive number, when another gets negative, evaluated error is less.

In addition, compared to Figure 1, as shown in Figure 2, the launching beam of FDA radar that the present invention proposes can focus on the impact point of expectation preferably, instead of be scattered in a distance to position angle on " the peak ridge " that be coupled.

Claims (7)

1. by the method at FDA radar estimating target distance and bearing angle, comprise the steps:

1) the transmitting array element of radar is divided into element number of array and equates the first transmitting subarray and the second transmitting subarray;

2) produce transmitting of two transmitting subarrays:

The frequency transmitting of the each array element in the first transmitting subarray is

f _c1，i＝f ₀+(i-1)·Δf ₁，i＝1，2，....M；

The frequency transmitting of the each array element in the second transmitting subarray is

f _c2，i＝f ₀+(i-1)·Δf ₂，i＝1，2，....M

M is the sum of array element in subarray, f ₀for radar system carrier frequency, Δ f ₁for the carrier frequency increment of predefined the first transmitting subarray, Δ f ₂for the carrier frequency increment of predefined the second transmitting subarray;

3) position angle of estimating target and distance:

$(\widehat{\mathrm{\θ}},\hat{r})=\underset{\mathrm{\θ},r}{\max }J(\mathrm{\θ},r)=\underset{\mathrm{\θ},r}{\max }{\left|w^H(\mathrm{\θ},r)y\right|}^2$

Wherein, w (θ, r) represents to receive the steering vector of signal, and θ is all possible position angle that receives signal beam, and r is all possible distance value that receives signal beam, and y is the signal receiving, () ^hrepresent conjugate transpose, for position angle and the distance of the target that estimates.

2. the method with FDA radar estimating target distance and bearing angle according to claim 1, in the time that the number of described transmitting array element is odd number,, taking the middle array element of array as mid point, array is divided into element number of array and equates the first transmitting subarray and the second transmitting subarray.

3. the method with FDA radar estimating target distance and bearing angle according to claim 1, the steering vector that the steering vector of described reception signal equals to transmit.

4. the method with FDA radar estimating target distance and bearing angle according to claim 3, the described steering vector transmitting is:

$a(\mathrm{\θ},r)={[1,e^{-j{\mathrm{\ω}}_1},...e^{-j(M-1){\mathrm{\ω}}_1},1,e^{-j{\mathrm{\ω}}_2},...e^{-j(M-1){\mathrm{\ω}}_2}]}^T$

[] ^tfor vectorial transposition computing, ω ₁represent adjacent two phase differential that array element transmits in the first transmitting subarray, ω ₂represent adjacent two phase differential that array element transmits in the second transmitting subarray.

5. the method with FDA radar estimating target distance and bearing angle according to claim 4, described ω ₁and ω ₂calculated by following formula:

${\mathrm{\ω}}_1=\frac{2\mathrm{\π}{f}_{0}d\sin \mathrm{\θ}}{c_0}-\frac{2\mathrm{\π\Δ}{f}_{1}r}{c_0},$ ${\mathrm{\ω}}_2=\frac{2\mathrm{\π}{f}_{0}d\sin \mathrm{\θ}}{c_0}-\frac{2\mathrm{\π\Δ}{f}_{2}r}{c_0}$

Wherein, θ is all possible position angle of wave beam of transmitting, and r is all possible distance value of wave beam of transmitting, the spacing that d is adjacent array element, c ₀for the light velocity.

6. the method with FDA radar estimating target distance and bearing angle according to claim 1, described Δ f ₁with Δ f ₂obtaining value method be: wherein any one gets positive number, and another gets negative.

7. a FDA radar, comprises the first transmitting subarray and the second transmitting subarray, and the frequency transmitting of the each array element in the first described transmitting subarray is:

f _c1，i＝f ₀+(i-1)·Δf ₁，i＝1，2，....M；

The frequency transmitting of the each array element in the second transmitting subarray is:

f _c2，i＝f ₀+(i-1)·Δf ₂，i＝1，2，....M；

M is the sum of array element in subarray, f ₀for radar system carrier frequency, Δ f ₁for the carrier frequency increment of predefined the first transmitting subarray, Δ f ₂for the carrier frequency increment of predefined the second transmitting subarray.