CN104122532A - Method for transmitting multi-beam formation and receiving signal processing simultaneously - Google Patents

Abstract

The invention provides a method for transmitting multi-beam formation and receiving signal processing simultaneously. The method comprises the following steps: selecting two groups of orthogonal multi-phase codes; modulating the medium-frequency sine signals of two groups of orthogonal multi-phase codes respectively by using a direct digital frequency synthesizer specific to each array element of a radar array antenna to obtain a first transmission signal waveform and a second transmission signal waveform; overlapping the produced first transmission signal waveform and second transmission signal waveform, performing frequency up-conversion to a required radiofrequency waveband, amplifying by using a linear power amplifier, and outputting to an antenna for transmitting; receiving an echo signal reflected by each transmission signal through a far field target by using the receiving end of a receiver; matching the receiving end with the echo signal respectively by using two matched filters, separating two groups of transmitted signals, transmitting obtained echo information to a data processing portion at the back end of the receiver for processing to obtain target information.

Description

A kind of multi-beam of simultaneously launching forms and receives the method for signal processing

Technical field

The invention belongs to phased array technology field, be specifically related to Digital Array Radar and launch multi-beam formation and receiving end signal waveform isolation technics simultaneously.

Background technology

Phased-array radar is called again phased-array radar, is a kind of Electronically Scanned Array radar that changes beam position to change the phase place that transmits.Compared with the radar that it carries out mechanical scanning with antenna, maximum difference is that antenna can make antenna beam rapid scanning without rotating.

Another advantage of phased-array radar is easy to form multiple wave beams exactly, and this advantage is that Phased Array Radars brings many new potentiality: thus the radiation coverage of expansion radar antenna improves Search/Track data transfer rate; Be convenient to realize Bistatic Radar System networking etc.Digital Array Radar (Digital Array Radar) is the digital phased-array radar that a kind of reception and launching beam are all realized with digital form.It can carry out the weighting of width phase at numeric field, realizes transmitting-receiving digital beam and forms, and its core technology is digital T/R assembly.

At present, the mode that phased-array radar transmitting multi-beam forms mainly contains two kinds, and one is timesharing transmitting multi-beam; Another kind is exactly to launch multi-beam simultaneously.Although first kind of way can simplified apparatus and reduced costs, and has also increased the difficulty of Continuous Tracking target, easily follow and lose target.For launching multi-beam simultaneously, at present, can adopt the analog form of multiple beam forming network (as Rotman lens) to realize, or large-scale radar emission array antenna is divided into several transmitting fronts, each front independently forms launching beam separately.For the former, use hard-wired analogy method, once after multiple beam forming network scheme determines, beam shape and beam position etc. are just fixing, are difficult for changing.Particularly can not the multiple wave beams of adaptive formation, antijamming capability is very poor.For the latter, radar antenna array is divided into L submatrix, and each submatrix independently forms wave beam, so, the energy of radar transmitter fails to be fully utilized, and the bore of antenna and peak transmitted power all drop to cuts apart front 1/L, has significantly reduced the angle measurement accuracy of radar.

Summary of the invention

For addressing the above problem, the invention provides a kind of multi-beam of simultaneously launching and form and receive the method for signal processing, utilize one group of matched filter of receiving end to isolate the orthogonal signal waveform of transmitting, thereby obtain the distance of multiple targets, the information such as speed.

Technical scheme of the present invention: a kind of multi-beam of simultaneously launching forms and receives the method for signal processing, comprises the following steps:

Step S1: select two groups of Polyphase Orthogonal Codes;

Step S2: to each array element of radar array antenna, utilize Direct Digital Synthesizer according to the modulated medium frequency sinusoidal signals respectively of two groups of Polyphase Orthogonal Codes in step S1, obtain first waveform and second waveform that transmits that transmits;

Step S3: first waveform and second that transmits producing is transmitted after waveform stack by upward frequency conversion to required radio-frequency range again, export antenna to and send after linear power amplifier amplifies;

Step S4: receiver receiving end receives each echoed signal reflecting through far field target that transmits;

Step S5: receiving end mates with echoed signal respectively with two matched filters, isolates two groups of signals of transmitting, then the data processing division divisional processing that the echo information obtaining is delivered to receiver rear end is obtained to target information;

Further, described target information comprises, the distance of target, the speed of target.

Beneficial effect of the present invention, a kind of multi-beam of simultaneously launching of the present invention forms and receives the method for signal processing, utilize the synthetic method of the multi-faceted phase weighting of Polyphase Orthogonal Code to form launching beam simultaneously, and utilize one group of matched filter of receiving end just can isolate the orthogonal signal waveform of transmitting, thereby obtain the distance of multiple targets, the information such as speed, have realized pinpoint function.

Brief description of the drawings

Fig. 1 is the structural drawing that the present invention launches the single transmission channel of multi-beam when realizing.

Fig. 2 is that phased-array radar transmitting receives model.

Fig. 3 is polyphase orthogonal code signal transmitting multi-beam figure.

Fig. 4 is receiving end matched filtering output map.

Embodiment

Below in conjunction with accompanying drawing examples, describe the present invention.

The invention provides a kind of multi-beam of simultaneously launching and form and receive the method for signal processing, launched by bay again at the linear composite signal of two orthogonal code waveforms through phase weighting of array antenna transmitting terminal transmitting and after amplifying through Linear Power Amplifier, can obtain the different wave beams that point to.Receiving antenna receives the signal that far field target reflects, and then just can isolate two through matched filter matching treatment and transmit.

A kind of multi-beam of simultaneously launching of the present invention forms and receives the method for signal processing, and concrete steps are as follows:

Step S1: select two groups of finite length Polyphase Orthogonal Codes, described orthogonal code choose follow code autocorrelation peak secondary lobe low, the low criterion of intersymbol cross-correlation peak value secondary lobe;

Suppose that orthogonal code collection S comprises L signal, the code element number of each signal is N, and encoding phase number is M, and l signal can be expressed as:

{s _l(k)＝exp[jφ _l(n)]}，

Wherein, l=1,2 ... L; N=f (N), N=1,2 ..., N; F (N) represents the value of N code element, and N represents the order of corresponding code element;

Encoding phase is taken as:

${\mathrm{\φ}}_l\left(n\right)\∈\{0,\frac{2\mathrm{\π}}{M},2\frac{2\mathrm{\π}}{M},...,(M-1)\frac{2\mathrm{\π}}{M}\},$

Wherein, the value of the corresponding M-1 of n, φ _l(n) represent N the corresponding encoding phase of code element

So whole block signal matrix can be expressed as:

$S(L,N,M)=\left[\begin{array}{cccc}{\mathrm{\φ}}_1\left(1\right)& {\mathrm{\φ}}_1\left(2\right)& ,...,& {\mathrm{\φ}}_1\left(N\right)\\ {\mathrm{\φ}}_2\left(1\right)& {\mathrm{\φ}}_2\left(2\right)& ,...,& {\mathrm{\φ}}_2\left(N\right)\\ .& .& & .\\ .& .& & .\\ .& .& & .\\ {\mathrm{\φ}}_L\left(1\right)& {\mathrm{\φ}}_L\left(2\right)& ,...,& {\mathrm{\φ}}_L\left(N\right)\end{array}\right];$

Step S2: to each array element of radar array antenna, utilize Direct Digital Synthesizer (DDS) to modulate respectively an intermediate frequency sinusoidal signal according to two groups of orthogonal codes that obtain in step S1, obtain two different waveform s that transmit ₁(k), s ₂(k), this wherein launches and points to respectively the first emission angle theta ₁, the second emission angle theta ₂the phase place adjustment of two wave beams, the first phase control words 1, second phase control words 2 of in the first Direct Digital Synthesizer DDS1, the second Direct Digital Synthesizer DDS2, giving by control system respectively complete;

Step S3: two digital signal stack outputs (as Fig. 1, supposing that bay number is K, taking k array element as example) that the first Direct Digital Synthesizer DDS1, the second Direct Digital Synthesizer DDS2 produce,

$s_1\left(k\right)e^{{-\mathrm{j\φ}}_{1k}}+s_2\left(k\right)e^{{-\mathrm{j\φ}}_{2k}},$

Wherein, k represents k array element, s ₁(k), s ₂(k) represent first of described k array element the transmit function expression of waveform of waveform and second that transmits, with represent respectively signal s ₁(k), s ₂(k) the phase weighting value of doing, φ _1kand φ _2krepresent respectively signal s ₁(k), s ₂(k) phase value of the weighting of doing;

Composite signal, through up-conversion, is delivered to Linear Power Amplifier input end and is gone out by antenna transmission after amplifying again after digital-to-analog conversion;

Step S4: as Fig. 2, array element 1 transmits as { s ₁₁+ s ₂₁, array element 2 transmits as { s ₁₂+ s ₂₂... array element K transmits as { s _1K+ s _2K,

The set of the signal composition of each array element transmitting is:

{s ₁₁+s ₂₁、s ₁₂+s ₂₂、...、s _1K+s _2K}

Wherein, $s_{\mathrm{ik}}=s_i\left(t\right)e^{{-\mathrm{j\φ}}_{\mathrm{ik}}},$ ${\mathrm{\φ}}_{\mathrm{ik}}=(k-1)\frac{2\mathrm{\π}d\sin \left({\mathrm{\θ}}_i\right)}{\mathrm{\λ}},$ φ _ikrepresent the phase value of k i signal weighting in array element passage, λ represents the wavelength that transmits, and d represents array element distance, i=1,2; K=1,2 ..., K, represent K array element;

Suppose that signal s1 (k), s2 (k) are τ from the time delay of launching after far field target reflects ₁, τ ₂, in this process, the propagation attenuation coefficient of signal is β ₁, β ₂;

The composite signal transmitting for each array element that receiving end receives, after down coversion, is designated as x (k)

$\begin{array}{c}x\left(k\right)={\mathrm{\β}}_1*\left(\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{s}_1(k-{\mathrm{\τ}}_1)e^{{-\mathrm{j\φ}}_{1k}}\right)+{\mathrm{\β}}_2*\left(\underset{z=1}{\overset{K}{\mathrm{\Σ}}}(k-{\mathrm{\τ}}_2)e^{{-\mathrm{j\φ}}_{2k}}\right)\\ =\underset{i=1}{\overset{2}{\mathrm{\Σ}}}{r}_i{s}_i(k-{\mathrm{\τ}}_i)=r_1{s}_1(k-{\mathrm{\τ}}_1)+r_2{s}_2(k-{\mathrm{\τ}}_2)\end{array},$

Wherein, k=1,2 ..., K, r ₁, r ₂represent respectively with ${\mathrm{\β}}_2*\underset{h=1}{\overset{K}{\mathrm{\Σ}}}{e}^{{-\mathrm{j\φ}}_{2k}},$

${\mathrm{\φ}}_{1k}=(k-1)*\frac{2\mathrm{\π}d\sin \left({\mathrm{\θ}}_1\right)}{c},$ ${\mathrm{\φ}}_{2k}=(k-1)*\frac{2\mathrm{\π}d\sin \left({\mathrm{\θ}}_2\right)}{c},$ C represents light velocity 3*10 ⁸m/s;

Step S5: known according to matched filter principle, with s _i(k) the impulse response h of the matched filter matching _i(k) should be s _i(k) mirror image function, that is:

h _i(k)＝s ^* _i(k _d-k)，

Wherein i=1,2, k _drepresent additional delay, " * " represents to get conjugation;

Note composite signal x (k) is y with the individual matched filter match output signal of j (j=1,2) _j(k), have:

$\begin{array}{c}{y}_j\left(k\right)=h_j\left(k\right)*x\left(k\right)={\∫}_{-\∞}^{+\∞}{h}_j\left(\mathrm{\τ}\right)x(k-\mathrm{\τ})\mathrm{d\τ}\\ ={\∫}_{-\∞}^{+\∞}{s^{*}}_j(k_d-\mathrm{\τ})x(k-\mathrm{\τ})\mathrm{d\τ}\\ \stackrel{\mathrm{\τ}=k_d-\mathrm{\τ}}{=}{\∫}_{-\∞}^{+\∞}{s^{*}}_j\left(\mathrm{\τ}\right)\left(\underset{i=1}{\overset{2}{\mathrm{\Σ}}}{r}_i{s}_i(k-k_d+\mathrm{\τ}-{\mathrm{\τ}}_i)\right)\mathrm{d\τ}\\ \stackrel{k=k_d}{=}{\∫}_{-\∞}^{+\∞}{s^{*}}_j\left(\mathrm{\τ}\right)\left(\underset{i=1}{\overset{2}{\mathrm{\Σ}}}{r}_i{s}_i(\mathrm{\τ}-{\mathrm{\τ}}_i)\right)\mathrm{d\τ}\end{array},$

Because of s _i(k) mutually orthogonal between, ${\∫}_{-\∞}^{+\∞}{s}_j^{*}\left(\mathrm{\τ}\right)s_i\left(\mathrm{\τ}\right)\mathrm{d\τ}=0,i\≠j,$ Therefore:

$y_j\left(k_d\right)={\∫}_{-\∞}^{+\∞}{s^{*}}_j\left(\mathrm{\τ}\right)r_j{s}_j(\mathrm{\τ}-{\mathrm{\τ}}_j)\mathrm{d\τ}(j=\mathrm{1,2}),$

Obtain the signal waveform y of transmitting ₁(k), y ₂(k),

Wherein, h _j(k) " * " in * x (k) represents convolution algorithm.

Result of the present invention can be verified by following Computer Simulation:

1. simulated conditions

In emulation, element number of array K=40, the centre frequency that transmits f ₀=1MHz, d/ λ=1/2 (d is that array element distance, λ are the wavelength that transmits), multi-beam is oriented to [0,45 °].Chosen the long N=40 of two group codes according to the well behaved principle of orthogonal code auto-correlation, simple crosscorrelation, phase encoding is counted four codings mutually of M=4, and by genetic algorithm, according to turning down mutually between two group code units, the two group code units that the criterion that auto-correlation is large obtains are in table one:

L signal can be expressed as:

{s _l(k)＝exp[jφ _l(n)]}，

Wherein, l=1,2 ... L; N=f (N), N=1,2 ..., N; , N represents the order of corresponding code element, the value of corresponding N the code element of f (N), and f (N) is 0,1 as shown in Table, value in 2,3 these four numbers;

Phase encoding is counted M=4, and encoding phase is taken as:

${\mathrm{\φ}}_l\left(n\right)\∈\{0,\frac{2\mathrm{\π}}{M},2\frac{2\mathrm{\π}}{M},...,(M-1)\frac{2\mathrm{\π}}{M}\},$

Wherein, the value of the corresponding M-1 of n, φ _l(n) represent N the corresponding encoding phase of code element

So whole block signal matrix can be expressed as:

$S(L,N,M)=\left[\begin{array}{cccc}{\mathrm{\φ}}_1\left(1\right)& {\mathrm{\φ}}_1\left(2\right)& ,...,& {\mathrm{\φ}}_1\left(N\right)\\ {\mathrm{\φ}}_2\left(1\right)& {\mathrm{\φ}}_2\left(2\right)& ,...,& {\mathrm{\φ}}_2\left(N\right)\\ .& .& & .\\ .& .& & .\\ .& .& & .\\ {\mathrm{\φ}}_L\left(1\right)& {\mathrm{\φ}}_L\left(2\right)& ,...,& {\mathrm{\φ}}_L\left(N\right)\end{array}\right]$

Table one or two group orthogonal code

2. emulation content

Utilize above-mentioned condition, by waveform s ₁(k), s ₂(k) carry out the phase weighting of corresponding different beams sensing, after amplifying through Linear Power Amplifier, can obtain the transmitting multi-beam simultaneously forming on space.As shown in Figure 3.

Receiving end utilizes matched filter just can isolate two orthogonal code signal waveforms of transmitting.As shown in Figure 4.It should be noted that, the side lobe peak after the pulse compression of phase-coded signal is very high.

In summary it can be seen, a kind of multi-beam of simultaneously launching of the present invention forms and receives the method for signal processing, utilize the synthetic method of the multi-faceted phase weighting of Polyphase Orthogonal Code to form launching beam simultaneously, and utilize one group of matched filter of receiving end just can isolate the orthogonal signal waveform of transmitting, thereby obtain the distance of multiple targets, the information such as speed, have realized and can form adaptively multiple wave beams, and accurately locate.

Those of ordinary skill in the art will appreciate that, embodiment described here is in order to help reader understanding's principle of the present invention, should be understood to that protection scope of the present invention is not limited to such special statement and embodiment.For a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment of doing, be equal to replacement, improvement etc., within all should being included in claim scope of the present invention.

Claims (8)

1. launch multi-beam simultaneously and form and receive a method for signal processing, it is characterized in that, comprise the following steps:

Step S1: select two groups of Polyphase Orthogonal Codes;

Step S2: to each array element of radar array antenna, utilize two Direct Digital Synthesizers to the modulated medium frequency sinusoidal signals respectively of two groups of Polyphase Orthogonal Codes in step S1, obtain first waveform and second waveform that transmits that transmits;

Step S3: first waveform and second that transmits producing is transmitted after waveform stack by upward frequency conversion to required radio-frequency range again, export antenna to and send after linear power amplifier amplifies;

Step S4: receiver receiving end receives each echoed signal reflecting through far field target that transmits;

Step S5: receiver receiving end is isolated two groups of signals of transmitting, then the data processing division divisional processing that the echo information obtaining is delivered to receiver rear end is obtained to target information;

Described target information comprises: the distance of target, the speed of target.

2. form and receive the method for signal processing according to a kind of multi-beam of launching of claim 1 simultaneously, it is characterized in that, described step S1 selects the algorithm of two groups of Polyphase Orthogonal Codes as follows:

Suppose that orthogonal code collection S comprises L signal, the code element number of each signal is N, and encoding phase number is M, and l signal can be expressed as:

{s _l(k)＝exp[jφ _l(n)]}，

Wherein, l=1,2 ... L; N=f (N), N=1,2 ..., N; F (N) represents the value of N code element, and N represents the order of corresponding code element;

Encoding phase is taken as:

Wherein, the value of the corresponding M-1 of n, φ _l(n) represent N the corresponding encoding phase of code element

So whole block signal matrix can be expressed as:

3. form and receive the method for signal processing according to a kind of multi-beam of launching of claim 1 simultaneously, it is characterized in that, in described step S2, first waveform that transmits points to the first emission angle and second waveform that transmits and points to the phase place adjustment of the second emission angle, and the first phase control words, second phase control words of in the first Direct Digital Synthesizer, the second Direct Digital Synthesizer, giving by control system respectively complete.

4. launch multi-beam according to claim 1 a kind of simultaneously form and receive the method for signal processing, it is characterized in that, waveform and the second waveform superposition algorithm that transmits that transmits of first in described step S3 is:

Wherein, k represents k array element, s ₁(k), s ₂(k) represent first of described k array element the transmit function expression of waveform of waveform and second that transmits, with represent respectively signal s ₁(k), s ₂(k) the phase weighting value of doing, φ _1kand φ _2krepresent respectively signal s ₁(k), s ₂(k) phase value of the weighting of doing.

5. form and receive the method for signal processing according to a kind of multi-beam of launching of claim 1 simultaneously, it is characterized in that, described step S4 specific algorithm is as follows:

Array element 1 transmits as { s ₁₁+ s ₂₁, array element 2 transmits as { s ₁₂+ s ₂₂... array element K transmits as { s _1K+ s _2K,

The set of the signal composition of each array element transmitting is:

{s ₁₁+s ₂₁、s ₁₂+s ₂₂、...、s _1K+s _2K}

Wherein, φ _ikrepresent the phase value of k i signal weighting in array element passage, λ represents the wavelength that transmits, and d represents array element distance, i=1,2; K=1,2 ..., K, represent K array element;

Suppose signal s ₁(k), s ₂(k) be τ from the time delay of launching after far field target reflects ₁, τ ₂, in this process, the propagation attenuation coefficient of signal is β ₁, β ₂;

The composite signal transmitting for each array element that receiving end receives, after down coversion, is designated as x (k)

Wherein, k=1,2 ..., K, r ₁, r ₂represent respectively with

c represents light velocity 3*10 ⁸m/s.

6. form and receive the method for signal processing according to a kind of multi-beam of launching of claim 1 simultaneously, it is characterized in that, described step S5 specific algorithm is as follows:

Known according to matched filter principle, with s _i(k) the impulse response h of the matched filter matching _i(k) should be s _i(k) mirror image function, that is:

h _i(k)＝s ^* _i(k _d-k)，

Wherein i=1,2, k _drepresent additional delay, " * " represents to get conjugation;

Note composite signal x (k) is y with the individual matched filter match output signal of j (j=1,2) _j(k), have:

Because of s _i(k) mutually orthogonal between, therefore:

Obtain the signal waveform y of transmitting ₁(k), y ₂(k),

Wherein, h _j(k) " * " in * x (k) represents convolution algorithm.

7. launch multi-beam according to claim 1 a kind of simultaneously form and receive the method for signal processing, it is characterized in that, the orthogonal code of described step S1 chooses that to follow the autocorrelation peak secondary lobe of code low, the low criterion of intersymbol cross-correlation peak value secondary lobe.

8. form and receive the method for signal processing according to a kind of multi-beam of launching of claim 1 simultaneously, it is characterized in that, described step S5 receiver receiving end mates with echoed signal respectively with two matched filters, isolates two groups of letters of transmitting.