CN104267399B - Linear array antenna orthogonal frequency MIMO-SAR R-T unit and method - Google Patents

Abstract

Disclose linear array antenna orthogonal frequency MIMO-SAR R-T unit and method.Comprise: MIMO transceiver controller and reference frequency source, produce reference signal; Waveform generator, produces subpulse base band linear FM signal according to reference signal; Local oscillation signal generation module, produces multichannel intermediate frequency local oscillator signal and multi-channel rf local oscillation signal according to reference signal; Orthogonal modulation module, antithetical phrase pulse base band linear FM signal and a road intermediate frequency local oscillator signal in orthogonal modulation, produce multichannel intermediate-freuqncy signal; Hyperchannel transmitter, to multichannel intermediate-freuqncy signal and the mixing of multi-channel rf local oscillation signal, generates multi-channel rf signal, multi-channel rf signal is sent to linear emission array antenna simultaneously; Multichannel receiver, receives the multi-path echo signal from linear receiving array antenna simultaneously, according to multi-channel rf local oscillation signal and multichannel intermediate frequency local oscillator signal to the demodulation of multi-path echo signal in orthogonal, generates multi-channel video echoed signal.Thus, MIMO (Multiple-Input Multiple-Out-put) while microwave signal being realized.

Description

Linear array antenna orthogonal frequency MIMO-SAR R-T unit and method

Technical field

The present invention relates to microwave imaging field, particularly, relate to a kind of linear array antenna orthogonal frequency MIMO-SAR (multiple-input and multiple-output-synthetic-aperture radar) R-T unit and method.

Background technology

The impact by landform, weather and the factor such as round the clock of traditional visual, optics or the measure such as infrared is larger, do not possess round-the-clock and ability to work that is round-the-clock, airborne array antenna forword-looking imaging system can not only penetrate cigarette, mist, cloud layer and floating dust etc., and do not affect by weather and climate, and the imaging of Real-time High Resolution rate can be carried out to region, aircraft front lower place, can also for the landing of aircraft, scouting, search and rescue and take off real terrestrial information is provided, strengthen navigation and the transport rescue ability of aircraft; In addition, adopt particular job frequency range, its radar system light weight and miniaturization are easy to realize, and enhance the adaptability of system and platform.

But existing airborne array antenna forword-looking imaging system realizes MIMO (Multiple-Input Multiple-Out-put) (MultiInputMultiOutput owing to adopting timesharing single-shot list receipts or the equivalence of single-shot many receipts working method, be called for short MIMO), and then obtain the echoed signal of observation area, therefore, also there is more problem to need to improve further.First, under comparable operating conditions, time-sharing receive and transmit(tsrt) working method needs the pulse repetition rate of raising system, and then reduces the not fuzzy imaging distance of system, is unfavorable for realizing large fabric width imaging; Secondly, due to Platform movement impact, time-sharing receive and transmit(tsrt) makes conventional data acquisition pattern " walk-stop-walk " no longer set up, and causes the complicacy of imaging processing and motion compensation; Finally, carry out timesharing single-shot list owing to adopting microwave switch network and receive or single-shot many receipts working method, single data obtaining time is longer, and system image refresh rate is relatively little.Therefore, in the urgent need to a kind of novel, can the microwave signal receiving and dispatching mechanism of MIMO simultaneously.

Summary of the invention

The object of this invention is to provide a kind of can simultaneously the linear array antenna orthogonal frequency MIMO-SAR R-T unit of MIMO and method.

To achieve these goals, the invention provides a kind of linear array antenna orthogonal frequency MIMO-SAR R-T unit, this device comprises: MIMO transceiver controller and reference frequency source, and this reference frequency source produces reference signal under the control of described MIMO transceiver controller; Waveform generator, is connected with described reference frequency source, for producing subpulse base band linear FM signal according to described reference signal; Local oscillation signal generation module, is connected with described MIMO transceiver controller and described reference frequency source, under the control of described MIMO transceiver controller, produces multichannel intermediate frequency local oscillator signal and multi-channel rf local oscillation signal according to described reference signal; Orthogonal modulation module, is connected with described local oscillation signal generation module and described waveform generator, for carrying out orthogonal modulation to described subpulse base band linear FM signal and a road intermediate frequency local oscillator signal, produces multichannel intermediate-freuqncy signal; Hyperchannel transmitter, be connected with described orthogonal modulation module and described local oscillation signal generation module, for carrying out mixing to described multichannel intermediate-freuqncy signal and multi-channel rf local oscillation signal, generate multi-channel rf signal, and described multi-channel rf signal is sent to the linear emission array antenna in linear array antenna simultaneously; And multichannel receiver, be connected with described local oscillation signal generation module, for receiving the multi-path echo signal from the linear receiving array antenna in described linear array antenna simultaneously, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, generate multi-channel video echoed signal.

Preferably, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, generate described multi-channel video echoed signal to comprise: carry out mixing to multi-channel rf local oscillation signal and received multi-path echo signal, form multichannel echo signal of intermediate frequency; And quadrature demodulation is carried out to described multichannel intermediate frequency local oscillator signal and described multichannel echo signal of intermediate frequency, generate described multi-channel video echoed signal.

Preferably, described local oscillation signal generation module comprises frequency synthesizer and the second power division network, wherein: described frequency synthesizer is used under the control of described MIMO transceiver controller, a described road intermediate frequency local oscillator signal and one group of 2N road radio-frequency (RF) local oscillator signal is produced according to described reference signal; And described second power division network is used for a described road intermediate frequency local oscillator signal to be divided into M group 2N road intermediate frequency local oscillator signal, and described one group of 2N road radio-frequency (RF) local oscillator signal is divided into M+1 group 2N road radio-frequency (RF) local oscillator signal, wherein, M is the receiving antenna quantity of described linear receiving array antenna, and 2N is the number of transmission antennas of described linear emission array antenna, and M >=2,2N >=2.

Preferably,

Wherein, L _synfor the horizontal direction size of described linear array antenna; Δ l _{h_tr}for the minimum level spacing between the arbitrary neighborhood separate transmit antenna array element aperture centre in described linear emission array antenna; And Δ l _{h_re}for the minimum level spacing between the arbitrary neighborhood individual reception bay aperture centre in described linear receiving array antenna.

Preferably, described orthogonal modulation module comprises quadrature modulator and the first power division network, wherein: described quadrature modulator is used for carrying out orthogonal modulation to described subpulse base band linear FM signal and a described road intermediate frequency local oscillator signal, generates a road intermediate-freuqncy signal; And described first power division network is used for a described road intermediate-freuqncy signal to be divided into 2N road intermediate-freuqncy signal.

Preferably, described hyperchannel transmitter comprises 2N transmitter, for carrying out mixing to one group of 2N road radio-frequency (RF) local oscillator signal in described 2N road intermediate-freuqncy signal and described M+1 group 2N road radio-frequency (RF) local oscillator signal, generate 2N road radiofrequency signal, and described 2N road radiofrequency signal is sent to described linear emission array antenna simultaneously.

Preferably, described multichannel receiver comprises M receiver, for according to remaining M group 2N road radio-frequency (RF) local oscillator signal in the radio-frequency (RF) local oscillator signal of described M+1 group 2N road and described M group 2N road intermediate frequency local oscillator signal carries out quadrature demodulation to received echoed signal, generate 2N × M road video echo signal.

The present invention also provides a kind of linear array antenna orthogonal frequency MIMO-SAR receiving/transmission method, and the method comprises: produce reference signal; Subpulse base band linear FM signal is produced according to described reference signal; Multichannel intermediate frequency local oscillator signal and multi-channel rf local oscillation signal is produced according to described reference signal; Orthogonal modulation is carried out to described subpulse base band linear FM signal and a road intermediate frequency local oscillator signal, produces multichannel intermediate-freuqncy signal; Mixing is carried out to described multichannel intermediate-freuqncy signal and multi-channel rf local oscillation signal, generates multi-channel rf signal, and described multi-channel rf signal is sent to the linear emission array antenna in linear array antenna simultaneously; And the multi-path echo signal simultaneously received from the linear receiving array antenna in described linear array antenna, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, generate multi-channel video echoed signal.

Preferably, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, the step generating described multi-channel video echoed signal comprises: carry out mixing to multi-channel rf local oscillation signal and received multi-path echo signal, forms multichannel echo signal of intermediate frequency; And quadrature demodulation is carried out to described multichannel intermediate frequency local oscillator signal and described multichannel echo signal of intermediate frequency, generate described multi-channel video echoed signal.

Preferably, comprise according to the step of described reference signal generation multichannel intermediate frequency local oscillator signal and multi-channel rf local oscillation signal: produce a described road intermediate frequency local oscillator signal and one group of 2N road radio-frequency (RF) local oscillator signal according to described reference signal; And a described road intermediate frequency local oscillator signal is divided into M group 2N road intermediate frequency local oscillator signal, described one group of 2N road radio-frequency (RF) local oscillator signal is divided into M+1 group 2N road radio-frequency (RF) local oscillator signal, wherein, M is the receiving antenna quantity of described linear receiving array antenna, and 2N is the number of transmission antennas of described linear emission array antenna, and M >=2,2N >=2.

Preferably,

Wherein, L _synfor the horizontal direction size of described linear array antenna; Δ l _{h_tr}for the minimum level spacing between the arbitrary neighborhood separate transmit antenna array element aperture centre in described linear emission array antenna; And Δ l _{h_re}for the minimum level spacing between the arbitrary neighborhood individual reception bay aperture centre in described linear receiving array antenna.

Preferably, orthogonal modulation is carried out to described subpulse base band linear FM signal and a described road intermediate frequency local oscillator signal, the step producing multichannel intermediate-freuqncy signal comprises: carry out orthogonal modulation to described subpulse base band linear FM signal and a described road intermediate frequency local oscillator signal, generate a road intermediate-freuqncy signal; And a described road intermediate-freuqncy signal is divided into 2N road intermediate-freuqncy signal.

Preferably, mixing is carried out to one group of 2N road radio-frequency (RF) local oscillator signal in described 2N road intermediate-freuqncy signal and described M+1 group 2N road radio-frequency (RF) local oscillator signal, generate 2N road radiofrequency signal, and described 2N road radiofrequency signal is sent to described linear emission array antenna.

Preferably, according to remaining M group 2N road radio-frequency (RF) local oscillator signal in the radio-frequency (RF) local oscillator signal of described M+1 group 2N road and described M group 2N road intermediate frequency local oscillator signal carries out quadrature demodulation to received echoed signal, generate 2N × M road video echo signal.

By linear array antenna orthogonal frequency MIMO-SAR R-T unit provided by the invention and method, MIMO (Multiple-Input Multiple-Out-put) working method while can microwave signal being realized.Compared with the time-sharing receive and transmit(tsrt) working method of routine, linear array antenna orthogonal frequency MIMO-SAR R-T unit provided by the invention and method, without the need to improving the pulse repetition rate of imaging system, are conducive to imaging system and realize remote not fuzzy imaging and large fabric width imaging.In addition, receiving and transmitting signal is simultaneously realized owing to adopting orthogonal frequency, make data acquisition scheme easily meet " walk-stop-walk " to suppose, in single data acquisition, the displacement of position of platform relativity distance is minimum, make corresponding imaging processing and motion compensation easy, conventional synthetic aperture radar image-forming disposal route can be adopted can to obtain the two dimensional image of observation area fast.In addition, by linear array antenna orthogonal frequency MIMO-SAR R-T unit provided by the invention and method, make single data obtaining time short, system image refresh rate is high, thus is conducive to the high time resolution imaging in implementation platform front.

Other features and advantages of the present invention are described in detail in embodiment part subsequently.

Accompanying drawing explanation

Accompanying drawing is used to provide a further understanding of the present invention, and forms a part for instructions, is used from explanation the present invention, but is not construed as limiting the invention with embodiment one below.In the accompanying drawings:

Fig. 1 is linear array antenna orthogonal frequency MIMO-SAR R-T unit provided by the invention and the linear array antenna example platforms applied of MIMO-SAR imaging system simultaneously;

The structural representation of MIMO-SAR imaging system while that Fig. 2 being linear array antenna according to the embodiment of the present invention;

Fig. 3 is three-dimensional layout's schematic diagram of linear array antenna according to the embodiment of the present invention;

Fig. 4 is the structural representation of linear array antenna orthogonal frequency MIMO-SAR R-T unit according to the embodiment of the present invention;

Fig. 5 is the structural representation of hyperchannel transmitter according to the embodiment of the present invention;

Fig. 6 is the structural representation of multichannel receiver according to the embodiment of the present invention;

Fig. 7 is the structural representation of the second power division network according to the embodiment of the present invention;

Fig. 8 is linear array antenna MIMO-SAR imaging transmitting-receiving simultaneously sequential control schematic diagram according to the embodiment of the present invention;

Fig. 9 is linear array antenna MIMO-SAR imaging phase center equivalent schematic simultaneously according to the embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in detail.Should be understood that, embodiment described herein, only for instruction and explanation of the present invention, is not limited to the present invention.

Fig. 1 shows linear array antenna orthogonal frequency MIMO-SAR R-T unit provided by the invention and the linear array antenna example platforms applied of MIMO-SAR imaging system simultaneously.As shown in Figure 1, linear array antenna orthogonal frequency MIMO-SAR R-T unit provided by the invention and linear array antenna simultaneously MIMO-SAR imaging system can be installed in the ventral of flying platform 22, and move with aircraft platform 22.Imaging system produces multi-channel rf signal by described MIMO-SAR R-T unit, and launches described multi-channel rf signal by linear array antenna simultaneously.Signal, after observation scene 21 reflects, becomes echoed signal, then receives described echoed signal by linear array antenna simultaneously.Afterwards, then receive these echoed signals via MIMO-SAR R-T unit simultaneously, and quadrature demodulation is carried out to it, form video echo signal.Finally, then this video echo signal is processed, to carry out imaging and image display.

In FIG, for the displaced phase center sampled point P of linear array antenna MIMO imaging simultaneously _apcposition coordinates, x _a, and z ₀represent the coordinate position that the displaced phase center sampled point of linear array antenna distributes along X, Y and Z, wherein n respectively _tr=1,2 ..., N, N+1 ..., 2N, m _re=1 ..., M, wherein, 2N is the quantity of the emitting antenna of linear emission array antenna in linear array antenna, and M is the quantity of the receiving antenna of linear receiving array antenna in linear array antenna, and, M>=2,2N>=2.Y-axis in rectangular coordinate system OXYZ can be parallel with linear array antenna, P _nfor the n-th scattering point target in observation scene 21, and position coordinates is (x _n, y _n, z _n).

Fig. 2 shows the structural representation of linear array antenna according to the embodiment of the present invention MIMO-SAR imaging system simultaneously.As shown in Figure 2, this imaging system can comprise described linear array antenna 11, comprise for while the linear emission array antenna 301 of emitting radio frequency signal and the linear receiving array antenna 302 for receiving echoed signal simultaneously; Linear array antenna orthogonal frequency MIMO-SAR R-T unit 12, for generation of multi-channel rf signal, and is sent to described linear emission array antenna 301 by described multi-channel rf signal simultaneously, to be launched by described linear emission array antenna 301 simultaneously; This MIMO-SAR R-T unit 12 also for receiving the multi-path echo signal from described linear receiving array antenna 302 simultaneously, and based on described multi-path echo signal generating video echoed signal; Data collector 13, for gathering described video echo signal from described MIMO-SAR R-T unit 12, and generates imaging echo digital signal according to received video echo signal; Pretreatment module 16, for carrying out phase compensation according to stationary phase deviation to described imaging echo digital signal; And imaging processing module 14, for carrying out imaging to the imaging echo digital signal after described phase compensation.In addition, this imaging system can also comprise the display module 15 for showing image, and/or for measuring the described position of linear array antenna 11 and the inertia measuring module of attitude.

System selectively operating frequency range is 8GHz ~ 300GHz.Under this frequency of operation, round-the-clock, the round-the-clock of system and the impact of the not factor such as climate and environment can be given full play to, can realize observing the high-resolution imaging of scene observe below flying platform, thus be conducive to assisting in flying platform and carry out front region imaging and detection etc.

Below by the composition and working principle of each assembly in specific descriptions imaging system provided by the invention.First, structure and the layout of linear array antenna according to the embodiment of the present invention composition graphs 3 are described.

Fig. 3 shows three-dimensional layout's schematic diagram of linear array antenna 11.Consider system receive-transmit isolation and dynamic range, system adopts bistatic structure, and namely emitting antenna and receiving antenna are separately.As shown in Figure 3, linear array antenna 11 can comprise for emitting radio frequency signal linear emission array antenna 301 (namely, " AC ") and for receive echoed signal linear receiving array antenna 302 (namely, " BD "), and the Antenna aperture of linear emission array antenna 301 and linear receiving array antenna 302 can be in the same plane.With reference to figure 3, linear emission array antenna 301 and linear receiving array antenna 302 center distance are vertically expressed as H _interval; Minimum level spacing in linear emission array antenna 301 between arbitrary neighborhood separate transmit antenna array element actinal surface geometric center is Δ l _{h_tr}, the minimum level spacing in linear receiving array antenna 302 between arbitrary neighborhood individual reception bay actinal surface geometric center is Δ l _{h_re}; T ₁..., T _n, T _n+1..., T _2Nrepresent the separate transmit antenna array element in linear emission array antenna 301, R ₁, R ₂, R _m..., R _mrepresent the individual reception bay in linear receiving array antenna 302, wherein N is the half of the number of transmission antennas of linear emission array antenna 301, and M is the receiving antenna quantity of linear receiving array antenna 302; L _{h_tr}represent that the separate transmit antenna array element level of linear emission array antenna 301 is to size, L _{v_tr}represent that the separate transmit antenna array element pitching of linear emission array antenna 301 is to size, L _{h_re}represent that the individual reception bay level of linear receiving array antenna 302 is to size, L _{v_re}represent that the individual reception bay pitching of linear receiving array antenna 302 is to size.Coordinate linear array antenna 11 can form 2MN displaced phase center sampled point by MIMO-SAR R-T unit 12 wherein n _tr=1,2 ..., N, N+1 ..., 2N, m _re=1 ..., M, as will be described in further detail below.

The horizontal direction size L of linear array antenna 11 _synby required system angle resolution ρ _θdetermine, particularly:

$L_{syn}=\frac{{\mathrm{\λ}}_c}{2{\mathrm{\ρ}}_{\mathrm{\θ}}}---\left(1\right)$

Wherein, λ _cfor the operation wavelength of linear array antenna orthogonal frequency MIMO-SAR R-T unit, ρ _θfor the angular resolution in system taken along line array antenna direction.

As mentioned above, linear array antenna 11 adopts bistatic pattern, is made up of linear emission array antenna 301 and linear receiving array antenna 302.As shown in Figure 3, the minimum level spacing between the arbitrary neighborhood separate transmit antenna array element aperture centre of linear emission array antenna 301 is Δ l _{h_tr}, and,

Δl _{h_tr}＝L _{h_tr}+l _tr(2)

Wherein, L _{h_tr}for the separate transmit antenna array element level of linear emission array antenna 301 is to size, l _trrepresent emitting antenna actinal surface gap, l _tr∈ (0, L _{h_tr}), i.e. l _trsize between 0 and separate transmit antenna array element level to size L _{h_tr}between, usual l _trget λ _c/ 16, L _{h_tr}for the operation wavelength λ of linear array antenna orthogonal frequency MIMO-SAR R-T unit _c0.25 ~ 2.0 times, namely

L _{h_tr}＝αλ _c(3)

Wherein, α ∈ [0.25,2.00];

Then the half (N) of the number of transmission antennas of the linear emission array antenna 301 of linear array antenna is:

Wherein, L _synfor the horizontal direction size of linear array antenna, Δ l _{h_tr}for linear emission array antenna 301 arbitrary neighborhood separate transmit antenna array element aperture centre between minimum level spacing, represent lower bracket function.

Accordingly, the receiving antenna quantity M of the linear receiving array antenna 302 of linear array antenna is:

Wherein, Δ l _{h_re}for linear receiving array antenna 302 arbitrary neighborhood individual reception bay aperture centre between minimum level spacing, || represent flow in upper plenum, and,

Δl _{h_re}＝NΔl _{h_tr}(6)

Number of transmission antennas 2N (or half N of number of transmission antennas) and receiving antenna quantity M is determined by equation (4) and (5), N+M can be made minimum, thus the stand-alone antenna array element quantity that can reduce needed for system, reduce system complexity.

As shown in Figure 3, linear emission array antenna 301 and linear receiving array antenna 302 present symmetrical result layout, and emitting antenna is positioned at two ends.The horizontal range of first individual reception bay geometric center of linear receiving array antenna 302 and first separate transmit antenna array element geometric center of linear emission array antenna 301 is Δ l _{h_re}/ 2; Equally, the horizontal range of last individual reception bay geometric center of linear receiving array antenna 302 and last emitting antenna array element geometric center of linear emission array antenna 301 is also Δ l _{h_re}/ 2.

In one embodiment of the invention, stand-alone antenna (comprising emitting antenna and receiving antenna) array element type can at least one in following: slot antenna, microstrip antenna, end-on-fire antenna, radiating guide, diectric antenna or dipole antenna.That is, linear emission array antenna 301 and linear receiving array antenna 302 can be made up of the stand-alone antenna array element of one or more types.

All separate transmit antenna array element polarization modes of linear emission array antenna 301 can be following in one: horizontal polarization, vertical polarization or circular polarisation.The polarization mode of linear emission array antenna 301 will be consistent.Similarly, all individual reception bay polarization modes of linear receiving array antenna 302 can be following in one: horizontal polarization, vertical polarization or circular polarisation.The polarization mode of linear receiving array antenna 302 also will be consistent.The polarization mode of linear emission array antenna 301 can be consistent with the polarization mode of linear receiving array antenna 302, also can be inconsistent, and to this, the present invention does not limit.

The foregoing describe the structure according to linear array antenna 11 provided by the invention and layout.To specifically describe below in imaging system of the present invention, the structure and working principle of linear array antenna orthogonal frequency MIMO-SAR R-T unit 12.

First, Fig. 4 shows the structural representation of described MIMO-SAR R-T unit 12 according to the embodiment of the present invention.As shown in Figure 4, this MIMO-SAR R-T unit 12 can comprise: MIMO transceiver controller 401 and reference frequency source 402, and this reference frequency source 402 produces reference signal under the control of described MIMO transceiver controller 401; Waveform generator 403, is connected with described reference frequency source 402, for producing subpulse base band linear FM signal according to described reference signal; Local oscillation signal generation module, is connected with described MIMO transceiver controller 401 and described reference frequency source 402, under the control of described MIMO transceiver controller 401, produces multichannel intermediate frequency local oscillator signal and multi-channel rf local oscillation signal according to described reference signal; Orthogonal modulation module, is connected with described local oscillation signal generation module and described waveform generator 403, for carrying out orthogonal modulation to described subpulse base band linear FM signal and a road intermediate frequency local oscillator signal, produces multichannel intermediate-freuqncy signal; Hyperchannel transmitter 406, be connected with described orthogonal modulation module and described local oscillation signal generation module, for carrying out mixing to described multichannel intermediate-freuqncy signal and multi-channel rf local oscillation signal, generate multi-channel rf signal, and described multi-channel rf signal is sent to the linear emission array antenna 301 in linear array antenna 11 simultaneously; And multichannel receiver 408, be connected with described local oscillation signal generation module, for receiving the multi-path echo signal from the linear receiving array antenna 302 in described linear array antenna 11 simultaneously, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, generate multi-channel video echoed signal.Wherein, described orthogonal modulation module can comprise quadrature modulator 404 and the first power division network 405, and described local oscillation signal generation module can comprise frequency synthesizer 411 and the second power division network 410.

Particularly, first, reference frequency source 402 produces a reference signal under the control of MIMO transceiver controller 401, and transfers to waveform generator 403 and frequency synthesizer 411.

Afterwards, reference signal is by producing subpulse base band linear FM signal s after waveform generator 403 _baset (), subpulse baseband signal bandwidth is B _s;

$B_s=\frac{B_r}{2N}+(1-\frac{1}{2N})B_0---\left(7\right)$

Wherein, B _rfor system synthesis complete signal bandwidth, B ₀for the overlapping bandwidth between the adjacent subpulse of frequency band.

In addition, frequency synthesizer 411, under the control of described MIMO transceiver controller 401, produces a road intermediate frequency local oscillator signal s according to described reference signal ₀(f _iF, t) He one group of 2N road radio-frequency (RF) local oscillator signal s _rF(f _nn, t), wherein nn=1,2 ... N, N+1 ..., 2N, f _iFfor intermediate frequency local oscillator signal frequency, f ₁, f ₂..., f _n, f _n+1..., f _2Nfor radio-frequency (RF) local oscillator signal frequency; T is variable signal duration, in addition, and all right various clock signals needed for synthesis system of this frequency synthesizer 411.

The road intermediate frequency local oscillator signal that described frequency synthesizer 411 generates is divided into 2N × M intermediate frequency local oscillator signal s by the second power division network 410 ₀(f _iF, t), that is, M group 2N road intermediate frequency local oscillator signal.In addition, one group of 2N road radio-frequency (RF) local oscillator signal that described frequency synthesizer 411 generates is divided into 2N × (M+1) individual radio-frequency (RF) local oscillator signal s by the second power division network 410 _rF(f _nn, t), that is, M+1 group 2N road radio-frequency (RF) local oscillator signal.Particularly, see Fig. 7, second power division network 410 can comprise multiple power splitter 701 and 703 (also can be replaced single-pole double-throw (SPDT) microwave switch or coupling mechanism) and multiple amplifier 702 and 704, and its function is (2N) × M road intermediate frequency local oscillator signal s by a described road intermediate frequency local oscillator Signal separator ₀(f _iF, t), and by each road radio-frequency (RF) local oscillator signal s _rF(f _nn, t) be separated into (M+1) road radio-frequency (RF) local oscillator signal, form the individual radio-frequency (RF) local oscillator signal s of 2N × (M+1) _rF(f _nn, t):

In addition, can 404 to described subpulse base band linear FM signal s by quadrature modulator _base(t) and a described road intermediate frequency local oscillator signal s ₀(f _iF, t) carry out orthogonal modulation, generate a road intermediate-freuqncy signal, afterwards, a described road intermediate-freuqncy signal is divided into 2N road intermediate-freuqncy signal s by the first power division network 405 _iF(f _iF, t):

s _IF(f _IF，t)＝[s _{IF_1}(f _IF，t)…s _{IF_N}(f _IF，t)

(9)

s _{IF_N+1}(f _IF，t)…s _{IF_2N}(f _IF，t)]

Afterwards, mixing can be carried out, radio frequency signal generation by hyperchannel transmitter 406 pairs of intermediate-freuqncy signals and radio-frequency (RF) local oscillator signal.Particularly, this hyperchannel transmitter 406 can comprise 2N transmitter 407, the corresponding emitting antenna of each transmitter.A described 2N transmitter is used for described 2N road intermediate-freuqncy signal s _iF(f _iF, t) with described M+1 group 2N road radio-frequency (RF) local oscillator signal s _rF(f _nn, one group of 2N road radio-frequency (RF) local oscillator signal s t) _rF(f _nn, t) carry out mixing, generate 2N road radiofrequency signal.Each transmitter 407 sends a road radiofrequency signal, to be launched by this emitting antenna simultaneously for emitting antenna corresponding in linear emission array antenna 301.

As shown in Figure 5, for each transmitter 407 in hyperchannel transmitter 406, it can comprise upconverter 501 and radio frequency amplifier 502.Described upconverter 501 may be used for one group of 2N road radio-frequency (RF) local oscillator signal Zhong mono-tunnel radio-frequency (RF) local oscillator signal s _rF(f _nn, t) with 2N road intermediate-freuqncy signal Zhong mono-tunnel intermediate-freuqncy signal s ₀(f _iF, t) carry out up-conversion, and amplified by radio frequency amplifier 502, thus obtain a road radiofrequency signal.Like this, 2N transmitter 407 just can generate 2N road RF signal S S _rF(f _{c_k}, t), and,

SS _RF(f _{c_k}，t)＝[ss _RF(f _{c_1}，t)…ss _RF(f _{c_k}，t)…ss _RF(f _{c_2N}，t)](10)

Wherein, a kth RF signal S S _rF(f _{c_k}, carrier frequency f t) _{c_k}for:

$\begin{array}{c}{f}_{c\_k}=f_c-(k-N+\frac{1}{2})(B_s-B_0),k=1,2,...,N,N+1,...,2N\\ =f_{IF}+f_{nn},nn=1,2,\mathrm{...},N,N+1,\mathrm{...},2N\end{array}---\left(11\right)$

Wherein, f _cfor the centre frequency of system synthesis complete signal; B ₀for the overlapping bandwidth between the adjacent subpulse of frequency band; Subpulse baseband signal bandwidth is B _s, also equal subpulse RF signal S S _rF(f _{c_k}, signal bandwidth t); f _iFfor intermediate frequency local oscillator signal frequency, f _nn=f ₁, f ₂..., f _n, f _n+1..., f _2Nfor radio-frequency (RF) local oscillator signal frequency.

After the radiofrequency signal of generation 2N road, by 2N road RF signal S S described in the radiation simultaneously of linear emission array antenna 301 _rF(f _{c_k}, t).These signals reflect to form echoed signal through observation scene 21, and are received by linear receiving array antenna 302 simultaneously, corresponding echoed signal SS _{rF_RE}(f _{c_k}, t) can be expressed as:

${\mathrm{SS}}_{RF\_RE}(f_{c\_k},t)=\underset{n}{\Σ}{\mathrm{\δ}}_n(x_n,y_n,z_n){\mathrm{SS}}_{RF}\[f_{c\_k},\left(t-\frac{2R_{m_{re}{n}_{tr}}}{C}\right)\]---\left(12\right)$

Wherein, δ _n(x _n, y _n, z _n) be corresponding target P _n(x _n, y _n, z _n) complex scattering coefficients; (x _n, y _n, z _n) be target P _nthree-dimensional coordinate; SS _rF(f _{c_k}, t) be the radiofrequency signal of linear emission array antenna 301 radiation; C is propagation velocity of electromagnetic wave; n _trrepresent the transmit antenna number in described linear emission array antenna 301, wherein, n _tr=1,2 ..., N, N+1 ..., 2N; m _rerepresent the receiving antenna numbering in described linear receiving array antenna 302, wherein, m _re=1 ..., M; be n-th _trthrough target P after individual transmitting stand-alone antenna array-element antenna transmits _nm is entered after reflecting _rethe propagation distance of individual reception stand-alone antenna array-element antenna, and,

$R_{m_{re}{n}_{tr}}=\frac{R_{n_{tr}\_n}+R_{m_{re}\_n}}{2}---\left(13\right)$

Wherein, for in linear emission array antenna 301 n-th _trindividual transmitting stand-alone antenna array-element antenna actinal surface geometric center is to the P of target _n(x _n, y _n, z _n) distance, and for m in linear receiving array antenna 302 _reindividual reception stand-alone antenna array-element antenna actinal surface geometric center is to the P of target _n(x _n, y _n, z _n) distance.

As previously mentioned, described multichannel receiver 408 receives the multi-path echo signal from the linear receiving array antenna 302 in described linear array antenna 11.Afterwards, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, generate multi-channel video echoed signal.

Particularly, first can carry out mixing to multi-channel rf local oscillation signal and received multi-path echo signal, form multichannel echo signal of intermediate frequency; And quadrature demodulation is carried out to described multichannel intermediate frequency local oscillator signal and described multichannel echo signal of intermediate frequency, generate described multi-channel video echoed signal.

Such as, as shown in Figure 4 and Figure 6, described multichannel receiver 408 can comprise M receiver 409, and each receiver 409 corresponds to a receiving antenna in linear receiving array antenna 302.Each receiving antenna receives the 2N road echoed signal reflected to form by 2N road radiofrequency signal, and thus, M receiver 409 can receive M group 2N road echoed signal altogether.A described M receiver 409 can according to remaining M group 2N road radio-frequency (RF) local oscillator signal (another group 2N road radio-frequency (RF) local oscillator signal be used to radio frequency signal generation in hyperchannel transmitter 406 as mentioned above) in the radio-frequency (RF) local oscillator signal of described M+1 group 2N road and described M group 2N road intermediate frequency local oscillator signal carries out quadrature demodulation to received echoed signal, generation 2N × M road video echo signal.

Particularly, for each receiver 409, it can comprise orthogonal demodulation circuit 601, wave filter 602, intermediate frequency amplifier 603, low-converter 604, low noise amplifier 605 and limiter 606.First, for single receiver 409, it receives one group of 2N road echoed signal, Gai Zu 2N road echoed signal is after limiter 606 and low noise amplifier 605, down-converted can be carried out with one group of 2N road radio-frequency (RF) local oscillator signal in the radio-frequency (RF) local oscillator signal of described M group 2N road in low-converter 604, afterwards, gained signal is admitted to intermediate frequency amplifier 603 and wave filter 602 carries out amplification and filtering process, thus one group of 2N road echo signal of intermediate frequency can be obtained (for M receiver 409, M group 2N road echo signal of intermediate frequency can be obtained altogether), echo signal of intermediate frequency can be represented as and:

Wherein, represent n-th _trthrough target P after individual transmitting stand-alone antenna array-element antenna transmits _nm is entered after reflecting _rethe propagation delay time variable of individual reception stand-alone antenna array-element antenna; be n-th _trthrough target P after individual transmitting stand-alone antenna array-element antenna transmits _nm is entered after reflecting _rethe propagation distance of individual reception stand-alone antenna array-element antenna; n _tr=1,2 ..., N, N+1 ..., 2N; m _re=1 ..., M.

After obtaining described M group 2N road echo signal of intermediate frequency, it is admitted to orthogonal demodulation circuit 601 and M group 2N road intermediate frequency local oscillator signal s ₀(f _iF, t) carry out quadrature demodulation, thus obtain M group 2N road video echo signal and:

From formula (14) and formula (15), by multichannel receiver 408, M × (2N) individual echo signal of intermediate frequency can be obtained, but the signal bandwidth of its each road echo signal of intermediate frequency is B _s, instead of B _r.Therefore, by MIMO-SAR R-T unit provided by the invention and imaging system, while the multiple displaced phase center of guarantee obtains, can also reduce the signal bandwidth of each Received signal strength, thus ensure the feasibility of real system.

The present invention also provides a kind of linear array antenna orthogonal frequency MIMO receiving/transmission method.The method can comprise: produce reference signal; Subpulse base band linear FM signal is produced according to described reference signal; Multichannel intermediate frequency local oscillator signal and multi-channel rf local oscillation signal is produced according to described reference signal; Orthogonal modulation is carried out to described subpulse base band linear FM signal and a road intermediate frequency local oscillator signal, produces multichannel intermediate-freuqncy signal; Mixing is carried out to described multichannel intermediate-freuqncy signal and multi-channel rf local oscillation signal, generates multi-channel rf signal, and described multi-channel rf signal is sent to the linear emission array antenna in linear array antenna simultaneously; And the multi-path echo signal simultaneously received from the linear receiving array antenna in described linear array antenna, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, generate multi-channel video echoed signal.

Wherein, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, the step generating described multi-channel video echoed signal can comprise: carry out mixing to multi-channel rf local oscillation signal and received multi-path echo signal, forms multichannel echo signal of intermediate frequency; And quadrature demodulation is carried out to described multichannel intermediate frequency local oscillator signal and described multichannel echo signal of intermediate frequency, generate described multi-channel video echoed signal.

In addition, can comprise according to the step of described reference signal generation multichannel intermediate frequency local oscillator signal and multi-channel rf local oscillation signal: produce a described road intermediate frequency local oscillator signal and one group of 2N road radio-frequency (RF) local oscillator signal according to described reference signal; And a described road intermediate frequency local oscillator signal is divided into M group 2N road intermediate frequency local oscillator signal s ₀(f _iF, t); Described one group of 2N road radio-frequency (RF) local oscillator signal is divided into M+1 group 2N road radio-frequency (RF) local oscillator signal.

In addition, orthogonal modulation is carried out to described subpulse base band linear FM signal and a described road intermediate frequency local oscillator signal, the step producing multichannel intermediate-freuqncy signal comprises: carry out orthogonal modulation to described subpulse base band linear FM signal and a described road intermediate frequency local oscillator signal, generate a road intermediate-freuqncy signal; And a described road intermediate-freuqncy signal is divided into 2N road intermediate-freuqncy signal.

Wherein, mixing is carried out to one group of 2N road radio-frequency (RF) local oscillator signal in described 2N road intermediate-freuqncy signal and described M+1 group 2N road radio-frequency (RF) local oscillator signal, generate 2N road radiofrequency signal, and described 2N road radiofrequency signal is sent to described linear emission array antenna.And, according to remaining M group 2N road radio-frequency (RF) local oscillator signal in the radio-frequency (RF) local oscillator signal of described M+1 group 2N road and described M group 2N road intermediate frequency local oscillator signal carries out quadrature demodulation to received echoed signal, generate 2N × M road video echo signal.

Now, just complete the transmitting-receiving process of MIMO (Multiple-Input Multiple-Out-put) while of signal, export described M group 2N road video echo signal by MIMO-SAR R-T unit 12

As mentioned above, imaging system provided by the invention can also comprise data collector 13, for gathering described video echo signal from described MIMO-SAR R-T unit 12, and generates imaging echo digital signal according to received video echo signal.

Particularly, data collector can form (not shown) by (2N) × (2M) road analog to digital converter (AnalogtoDigitalconverter, AD).The video echo signal that every No. 2 analog to digital converters complete 1 receiver channel quantizes, as completed SS _rE(τ ₁₁) video echo signal of passage quantizes, and forms I and Q two paths of signals.To video echo signal quantize, quantization digit is 8 ~ 14bit, sample rate f _sfor signal bandwidth B _s1.1 ~ 1.5 times, usually get 1.2 times.Should be understood that, the specific implementation of data acquisition is well known for the person skilled in the art, and therefore the present invention is not described in detail at this.

Video echo signal is realized by data collector 13 gather, and obtain the corresponding capable imaging echo digital signal of (2N) × M

${\mathrm{SS}}_{RE}\left({\mathrm{\τ}}_{m_{re}{n}_{tr}},f_s,f_{c\_k}\right)=\left[\begin{array}{c}{\mathrm{ss}}_{RE\_11}\left({\mathrm{\τ}}_{m_{re}{n}_{tr}},f_s,f_{c\_k}\right)\\ .\\ .\\ .\\ {\mathrm{ss}}_{RE\_m_{re}{n}_{tr}}\left({\mathrm{\τ}}_{m_{re}{n}_{tr}},f_s,f_{c\_k}\right)\\ .\\ .\\ .\\ {\mathrm{ss}}_{RE\_M\left(2N\right)}\left({\mathrm{\τ}}_{m_{re}{n}_{tr}},f_s,f_{c\_k}\right)\end{array}\right]---\left(16\right)$

Afterwards, pretreatment module 16 can carry out phase compensation according to stationary phase deviation to described imaging echo digital signal.The object of carrying out phase compensation is spliced signal subspace band, becomes the signal that a bandwidth is complete, to realize widening of signal bandwidth, thus is convenient to imaging processing.

Particularly, as in Fig. 1, for displaced phase center sampled point P _apcposition coordinates, x _a, and z ₀represent the coordinate position that the displaced phase center sampled point of linear array antenna distributes along X, Y and Z, n respectively _tr=1,2 ..., N, N+1 ..., 2N, m _re=1 ..., M, P _nfor the coordinate (x of target in observation scene 21 _n, y _n, z _n), corresponding target scattering coefficient is designated as δ _n(x _n, y _n, z _n), then a certain road imaging echo digital signal can be expressed as:

$\begin{array}{c}{\mathrm{ss}}_{RE\_m_{re}{n}_{tr}}\left({\mathrm{\τ}}_{m_{re}{n}_{tr}},f_s,f_{c\_k}\right)\\ =\underset{n}{\mathrm{\Σ}}\mathrm{\δ}\left(x_n,y_n,z_n\right)\exp \[j\mathrm{\π}\left(-\frac{4{\mathrm{\πR}}_{m_{re}{n}_{tr}}{f}_{c\_k}}{C}+K_{rk}{\left(t-\frac{2R_{m_{re}{n}_{tr}}}{C}\right)}^2\right)\]\\ \×rect\[\frac{\left(t-\frac{2R_{m_{re}{n}_{tr}}}{C}\right)}{T_{rk}}\]\end{array}---\left(17\right)$

Wherein, f _srepresent sampling rate, f _sfor signal bandwidth B _s1.1 ~ 1.5 times, usually get 1.2 times, m represents m road imaging echo digital signal, m=1,2,3 ..., (2NM), f _{c_k}for the radiofrequency signal carrier frequency of a kth transmission channel, k=1,2 ..., N, N+1 ..., 2N; be n-th _trthrough target P after individual transmitting stand-alone antenna array-element antenna transmits _nm is entered after reflecting _rethe propagation distance of individual reception stand-alone antenna array-element antenna; with to be respectively in linear emission array antenna 301 n-th _trm in individual transmitting stand-alone antenna array-element antenna actinal surface geometric center and linear receiving array antenna 302 _reindividual reception stand-alone antenna array-element antenna actinal surface geometric center is to the P of target _n(x _n, y _n, z _n) distance; C is propagation velocity of electromagnetic wave; K _rkfor subpulse linear FM signal frequency modulation rate; T _rkfor the subpulse linear FM signal duration, B _s=K _rkt _rk; Rect [t/T _rk] be time window function, wherein,

$rect\[\frac{t}{T_{rk}}\]=\left\{\begin{array}{cc}1& \left|t\right|\≤T_{rk}/2\\ 0& others\end{array}\right.---\left(18\right)$

In actual applications, as shown in Figure 1, because the separate transmit antenna array element in linear emission array antenna 301 and the individual reception bay in linear receiving array antenna 302 distance relative antenna is between any two general very short to ground oblique distance, subband splicing can be realized by compensating stationary phase deviation:

Wherein, represent stationary phase deviation,

$d_{m_{re}{n}_{tr}{f}_{c\_k}}\left(m_{re},n_{tr},k\right)=\left[\begin{array}{ccccc}{d}_{11f_{c\_1}}& \mathrm{...}& d_{11f_{c\_N}}& \mathrm{...}& d_{11f_{c\_2N}}\\ .& .& .& .& .\\ .& .& .& .& .\\ .& .& .& .& .\\ d_{m_{re}{n}_{tr}{f}_{c\_1}}& \mathrm{...}& d_{m_{re}{n}_{tr}{f}_{c\_N}}& \mathrm{...}& d_{m_{re}{n}_{tr}{f}_{c\_2N}}\\ .& .& .& .& .\\ .& .& .& .& .\\ .& .& .& .& .\\ d_{M\left(2N\right)f_{c\_1}}& \mathrm{...}& d_{M\left(2N\right)f_{c\_N}}& \mathrm{...}& d_{M\left(2N\right)f_{c\_2N}}\end{array}\right]---\left(20\right)$

Wherein, represent displaced phase center sampled point to displaced phase center sampled point between distance, represent n-th _trindividual transmitting stand-alone antenna array-element antenna and m _rethe displaced phase center sampled point that individual reception stand-alone antenna array-element antenna is formed, expression kth (k=1,2 ..., N, N+1 ..., 2N) and individual transmitting stand-alone antenna array-element antenna and m _rethe displaced phase center sampled point that individual reception stand-alone antenna array-element antenna is formed.By known, for the signal that each receiving cable receives, be not the signal of a complete bandwidth, but a carrier frequency is f _{c_k}, bandwidth is B _ssubband signal, therefore, need to synthesize a complete signal bandwidth B by phase compensation _rsignal, especially, work as k=n _tr,

Also namely, by n-th _trindividual transmitting stand-alone antenna array-element antenna actinal surface geometric center and m _rethe displaced phase center sampled point that individual reception stand-alone antenna array-element antenna is formed its signal bandwidth is B _s, need to utilize m _rekth (k ≠ n that individual reception stand-alone antenna array-element antenna receives _tr) subband signal launched of individual transmitting stand-alone antenna array-element antenna splices, and splices the complete signal of a bandwidth by subband joining method.By this mode, each receiving cable can be made to be equivalent at respective displaced phase center place internal loopback, as shown in Figure 9.Signal after phase compensation (that is, subband splicing) can be expressed as:

$\begin{array}{c}{\mathrm{ss}}_{RE\_m_{re}{n}_{tr}}\left({\mathrm{\τ}}_{m_{re}{n}_{tr}},B_r\right)\\ =\underset{k=1,\mathrm{...},N,N+1,\mathrm{...},2N}{\mathrm{\Σ}}{\mathrm{ss}}_{RE\_m_{re}k}\left({\mathrm{\τ}}_{m_{re}{n}_{tr}=k},f_s,f_{c\_k}\right)*s\[d_{m_{re}{n}_{tr}{f}_{c\_k}}\left(m_{re},n_{tr},k\right),f_{c\_k}\]\\ \≈\underset{n}{\mathrm{\Σ}}\mathrm{\δ}\left(x_n,y_n,z_n\right)\exp \[j\mathrm{\π}\left(-\frac{4{\mathrm{\πR}}_n{f}_c}{C}+K_r{\left(t-\frac{2R_n}{C}\right)}^2\right)\]rect\[\frac{\left(t-\frac{2R_n}{C}\right)}{2{\mathrm{NT}}_{rk}}\]\end{array}---\left(21\right)$

$R=\sqrt{{(x_a-x_n)}^2+{(y_{m_{re}{n}_{tr}}-y_n)}^2+{(z_0-z_n)}^2}---\left(22\right)$

Wherein, represent n-th _tr=k is launched stand-alone antenna array-element antenna transmitting carrier frequency be carrier frequency is f _{c_k}bandwidth is B _ssubband signal, and m _reimaging echo digital signal corresponding to individual reception stand-alone antenna array-element antenna receives; f _srepresent sampling rate, f _sfor signal bandwidth B _s1.1 ~ 1.5 times, usually get 1.2 times, m represents m road imaging echo digital signal, m=1,2,3 ..., (2NM), B _rfor system synthesis complete signal bandwidth, R _nfor displaced phase center to target P _n(x _n, y _n, z _n) distance, and K _r=K _rk; Wherein, x _aand z ₀can determine in the following way: the attitude and the location parameter that are obtained some transmitting stand-alone antenna array-element antenna actinal surface geometric centers or reception stand-alone antenna array-element antenna actinal surface geometric center by inertia measuring module, then calculate the location parameter x of displaced phase center sampled point by attitude and location parameter _aand z ₀, concrete computation process can list of references (Yang Xiaolin. linear array imaging radar system design and amplitude phase error Concordance technique study. [doctorate]. Postgraduate School, Chinese Academy of Sciences, 2014.).

Further formula (20) is represented, launches stand-alone antenna array-element antenna and the 1st with the 1st and receive displaced phase center sampled point that stand-alone antenna array-element antenna formed and correspond to full bandwidth signal and can be expressed as:

$\begin{array}{c}{\mathrm{ss}}_{RE\_m_{re}=1n_{tr}=1}\left({\mathrm{\τ}}_{m_{re}=1n_{tr}=1},B_r\right)\\ =\underset{k=1,\mathrm{...},N,N+1,\mathrm{...},2N}{\mathrm{\Σ}}{\mathrm{ss}}_{RE\_1k}\left({\mathrm{\τ}}_{m_{re}=1n_{tr}=k},f_s,f_{c\_k}\right)*s\left(d_{m_{re}=1n_{tr}={\mathrm{kf}}_{c\_k}}\left(m_{re}=1,n_{tr}=k,k\right),f_{c\_k}\right)\\ \≈\underset{n}{\mathrm{\Σ}}\mathrm{\δ}\left(x_n,y_n,z_n\right)\exp \[j\mathrm{\π}\left(-\frac{4{\mathrm{\πR}}_n{f}_c}{C}+K_r{\left(t-\frac{2R_n}{C}\right)}^2\right)\]rect\[\frac{\left(t-\frac{2R_n}{C}\right)}{2{\mathrm{NT}}_{rk}}\]\end{array}---\left(23\right)$

$R=\sqrt{{(x_a-x_n)}^2+{(y_{m_{re}=1n_{tr}=1}-y_n)}^2+{(z_0-z)}^2}---\left(24\right)$

Finally, imaging can be carried out by imaging processing module 14 to the imaging echo digital signal after described phase compensation.Multiple existing formation method can be adopted to carry out imaging, such as, conventional synthetic aperture radar image-forming algorithm (such as, range Doppler algorithm, CS (ChirpScaling) algorithm, polar format algorithm etc.) can be adopted to carry out imaging processing.Described imaging processing module 14 can be such as computing machine or dsp processor.In addition, image display can also be carried out by display module 15, check for user.

The present invention also provides a kind of linear array antenna MIMO formation method simultaneously.The method can comprise: produce multi-channel rf signal, and described multi-channel rf signal is sent to the linear emission array antenna in linear array antenna simultaneously; Launch described multi-channel rf signal by described linear emission array antenna simultaneously; Receive the multi-path echo signal from the linear receiving array antenna in described linear array antenna simultaneously, and based on described multi-path echo signal generating video echoed signal; Imaging echo digital signal is generated according to described video echo signal; According to stationary phase deviation, phase compensation is carried out to described imaging echo digital signal; And imaging is carried out to the imaging echo digital signal after described phase compensation.

Thus, linear array antenna provided by the invention is MIMO-SAR imaging system and method simultaneously, and once namely can be obtained the two dimensional image of observation area by transmitting-receiving, relative conventional system needs by multiple signal, greatly provides the image refresh rate of system.Particularly, the while of linear array antenna, a data acquisition shortest time of MIMO-SAR imaging system is:

${\mathrm{\ΔT}}_{min}=T_{win}=\frac{2(R_{max}-R_{min})}{C}+T_{rk}---\left(25\right)$

Wherein, T _winrepresent the sample window time; R _maxand R _minrespectively represent system farthest with nearest observed range; T _rkrepresent the subpulse linear FM signal duration.And a data acquisition maximum duration is determined by trigger action frequency, can need to adjust according to user, as shown in Figure 8, thus high time resolution imaging capability system being possessed not available for conventional system.And conventional system is launched for 2N time because needs adopt, therefore, data acquisition shortest time is at least 2N times of linear array antenna of the present invention MIMO-SAR imaging system acquisition time simultaneously.

In sum, by linear array antenna orthogonal frequency MIMO-SAR R-T unit provided by the invention and method, MIMO-SAR imaging system and method can not only penetrate the materials such as cigarette, mist, cloud layer and floating dust to linear array antenna simultaneously, and do not affect by weather and climate, and, compared with conventional airborne array antenna forword-looking imaging, it also possesses following advantage:

1, without the need to improving the pulse repetition rate of system, remote not fuzzy imaging and the large fabric width imaging of realization of system is conducive to;

2, because system adopts orthogonal frequency to realize receiving and transmitting signal simultaneously, make data acquisition scheme easily meet " walk-stop-walk " to suppose, in single data acquisition, the displacement of position of platform relativity distance is minimum, corresponding imaging processing and motion compensation easy, conventional synthetic aperture radar image-forming disposal route can be adopted can to obtain the two dimensional image of observation area fast;

3, single data obtaining time is short, and system image refresh rate is high, is conducive to the high time resolution imaging in implementation platform front;

4, system can carry out the imaging of Real-time High Resolution rate to aircraft forward region, can provide image information for the landing of aircraft, scouting and search and rescue etc.

Below the preferred embodiment of the present invention is described in detail by reference to the accompanying drawings; but; the present invention is not limited to the detail in above-mentioned embodiment; within the scope of technical conceive of the present invention; can carry out multiple simple variant to technical scheme of the present invention, these simple variant all belong to protection scope of the present invention.

It should be noted that in addition, each the concrete technical characteristic described in above-mentioned embodiment, in reconcilable situation, can be combined by any suitable mode.In order to avoid unnecessary repetition, the present invention illustrates no longer separately to various possible array mode.

In addition, also can carry out combination in any between various different embodiment of the present invention, as long as it is without prejudice to thought of the present invention, it should be considered as content disclosed in this invention equally.

Claims (8)

1. a linear array antenna orthogonal frequency MIMO-SAR R-T unit, is characterized in that, this device comprises:

MIMO transceiver controller and reference frequency source, this reference frequency source produces reference signal under the control of described MIMO transceiver controller;

Waveform generator, is connected with described reference frequency source, for producing subpulse base band linear FM signal according to described reference signal;

Local oscillation signal generation module, be connected with described MIMO transceiver controller and described reference frequency source, for under the control of described MIMO transceiver controller, multichannel intermediate frequency local oscillator signal and multi-channel rf local oscillation signal is produced according to described reference signal, described local oscillation signal generation module comprises frequency synthesizer and the second power division network, wherein: described frequency synthesizer is used under the control of described MIMO transceiver controller, produces a road intermediate frequency local oscillator signal and one group of 2N road radio-frequency (RF) local oscillator signal according to described reference signal; And described second power division network is used for a described road intermediate frequency local oscillator signal to be divided into M group 2N road intermediate frequency local oscillator signal, and described one group of 2N road radio-frequency (RF) local oscillator signal is divided into M+1 group 2N road radio-frequency (RF) local oscillator signal, wherein, M is the receiving antenna quantity of described linear receiving array antenna, and 2N is the number of transmission antennas of described linear emission array antenna, and M >=2,2N >=2;

Orthogonal modulation module, is connected with described local oscillation signal generation module and described waveform generator, for carrying out orthogonal modulation to described subpulse base band linear FM signal and a described road intermediate frequency local oscillator signal, produces multichannel intermediate-freuqncy signal;

Hyperchannel transmitter, be connected with described orthogonal modulation module and described local oscillation signal generation module, for carrying out mixing to described multichannel intermediate-freuqncy signal and multi-channel rf local oscillation signal, generate multi-channel rf signal, and described multi-channel rf signal is sent to the linear emission array antenna in linear array antenna simultaneously; And

Multichannel receiver, be connected with described local oscillation signal generation module, for receiving the multi-path echo signal from the linear receiving array antenna in described linear array antenna simultaneously, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, generate multi-channel video echoed signal.

2. device according to claim 1, it is characterized in that, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, generate described multi-channel video echoed signal to comprise: carry out mixing to multi-channel rf local oscillation signal and received multi-path echo signal, form multichannel echo signal of intermediate frequency; And quadrature demodulation is carried out to described multichannel intermediate frequency local oscillator signal and described multichannel echo signal of intermediate frequency, generate described multi-channel video echoed signal.

3. device according to claim 1, is characterized in that,

Wherein, L _synfor the horizontal direction size of described linear array antenna; Δ l _{h_tr}for the minimum level spacing between the arbitrary neighborhood separate transmit antenna array element aperture centre in described linear emission array antenna; And Δ l _{h_re}for the minimum level spacing between the arbitrary neighborhood individual reception bay aperture centre in described linear receiving array antenna.

4. device according to claim 1, it is characterized in that, described orthogonal modulation module comprises quadrature modulator and the first power division network, wherein: described quadrature modulator is used for carrying out orthogonal modulation to described subpulse base band linear FM signal and a described road intermediate frequency local oscillator signal, generates a road intermediate-freuqncy signal; And described first power division network is used for a described road intermediate-freuqncy signal to be divided into 2N road intermediate-freuqncy signal;

Described hyperchannel transmitter comprises 2N transmitter, for carrying out mixing to one group of 2N road radio-frequency (RF) local oscillator signal in described 2N road intermediate-freuqncy signal and described M+1 group 2N road radio-frequency (RF) local oscillator signal, generate 2N road radiofrequency signal, and described 2N road radiofrequency signal is sent to described linear emission array antenna simultaneously; And

Described multichannel receiver comprises M receiver, for according to remaining M group 2N road radio-frequency (RF) local oscillator signal in the radio-frequency (RF) local oscillator signal of described M+1 group 2N road and described M group 2N road intermediate frequency local oscillator signal carries out quadrature demodulation to received echoed signal, generate 2N × M road video echo signal.

5. a linear array antenna orthogonal frequency MIMO-SAR receiving/transmission method, it is characterized in that, the method comprises:

Produce reference signal;

Subpulse base band linear FM signal is produced according to described reference signal;

Produce multichannel intermediate frequency local oscillator signal and multi-channel rf local oscillation signal according to described reference signal, comprising:

A road intermediate frequency local oscillator signal and one group of 2N road radio-frequency (RF) local oscillator signal is produced according to described reference signal; And

A described road intermediate frequency local oscillator signal is divided into M group 2N road intermediate frequency local oscillator signal, described one group of 2N road radio-frequency (RF) local oscillator signal is divided into M+1 group 2N road radio-frequency (RF) local oscillator signal, wherein, M is the receiving antenna quantity of described linear receiving array antenna, and 2N is the number of transmission antennas of described linear emission array antenna, and M >=2,2N >=2;

Orthogonal modulation is carried out to described subpulse base band linear FM signal and a described road intermediate frequency local oscillator signal, produces multichannel intermediate-freuqncy signal;

Mixing is carried out to described multichannel intermediate-freuqncy signal and multi-channel rf local oscillation signal, generates multi-channel rf signal, and described multi-channel rf signal is sent to the linear emission array antenna in linear array antenna simultaneously; And

Receive the multi-path echo signal from the linear receiving array antenna in described linear array antenna simultaneously, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, generate multi-channel video echoed signal.

6. method according to claim 5, it is characterized in that, according to multi-channel rf local oscillation signal and described multichannel intermediate frequency local oscillator signal, quadrature demodulation is carried out to received multi-path echo signal, the step generating described multi-channel video echoed signal comprises: carry out mixing to multi-channel rf local oscillation signal and received multi-path echo signal, forms multichannel echo signal of intermediate frequency; And quadrature demodulation is carried out to described multichannel intermediate frequency local oscillator signal and described multichannel echo signal of intermediate frequency, generate described multi-channel video echoed signal.

7. method according to claim 5, is characterized in that,

Wherein, L _synfor the horizontal direction size of described linear array antenna; Δ l _{h_tr}for the minimum level spacing between the arbitrary neighborhood separate transmit antenna array element aperture centre in described linear emission array antenna; And Δ l _{h_re}for the minimum level spacing between the arbitrary neighborhood individual reception bay aperture centre in described linear receiving array antenna.

8. method according to claim 5, it is characterized in that, orthogonal modulation is carried out to described subpulse base band linear FM signal and a described road intermediate frequency local oscillator signal, the step producing multichannel intermediate-freuqncy signal comprises: carry out orthogonal modulation to described subpulse base band linear FM signal and a described road intermediate frequency local oscillator signal, generate a road intermediate-freuqncy signal; And a described road intermediate-freuqncy signal is divided into 2N road intermediate-freuqncy signal;

Mixing is carried out to one group of 2N road radio-frequency (RF) local oscillator signal in described 2N road intermediate-freuqncy signal and described M+1 group 2N road radio-frequency (RF) local oscillator signal, generates 2N road radiofrequency signal, and described 2N road radiofrequency signal is sent to described linear emission array antenna; And

According to remaining M group 2N road radio-frequency (RF) local oscillator signal in the radio-frequency (RF) local oscillator signal of described M+1 group 2N road and described M group 2N road intermediate frequency local oscillator signal carries out quadrature demodulation to received echoed signal, generate 2N × M road video echo signal.