Hypersonic aircraft Larger Dynamic Doppler quick capturing method and communication system
阅读说明：本技术 高超声速飞行器大动态多普勒快速捕获方法及通信系统 (Hypersonic aircraft Larger Dynamic Doppler quick capturing method and communication system ) 是由 石磊 赵蕾 姚博 袁淑容 朱从莹 李小平 于 2019-07-22 设计创作，主要内容包括：本发明属于无线通信技术领域,公开了一种高超声速飞行器大动态多普勒快速捕获方法及通信系统,首先采取盲快速估计算法对接收信号的多普勒速率进行快速估计；利用估计得到的多普勒速率对接收信号进行补偿,针对补偿后的接收信号在多个连续符号上进行傅里叶变换,接着对多个符号傅里叶变换的结果进行平方累积平均；最后对累积结果进行峰值搜索,其中最大峰值即为捕获到的多普勒频偏值,接收信号多普勒速率已经通过盲估计算法得到。基于飞行条件预估的多普勒搜索范围修正环节将谱峰搜索限制在更小的范围内,以进一步提高载波信号的捕获精度和捕获速度。本发明提高了载波信号捕获概率及捕获速度,可应用于高超声速飞行器快速/实时测控通信。(The invention belongs to wireless communication technology field, a kind of hypersonic aircraft Larger Dynamic Doppler quick capturing method and communication system are disclosed, blind Fast Estimation Algorithm is taken quickly to estimate the Doppler rate for receiving signal first；The Doppler rate obtained using estimation is compensated to signal is received, and Fourier transformation is carried out on multiple continuous symbols for compensated reception signal, then carries out square cumulative mean to the result of multiple symbol Fourier transformations；Peak value searching finally is carried out to accumulation results, wherein peak-peak is the Doppler shift value captured, and reception signal Doppler rate has passed through blind estimate algorithm and obtained.Spectrum peak search is limited in smaller range based on the doppler searching range amendment link that flying condition is estimated, to further increase the acquisition accuracy and acquisition speed of carrier signal.The present invention improves carrier signal acquisition probability and acquisition speed, can be applied to hypersonic aircraft quickly/real-tune TT & C communication.)
1. a kind of hypersonic aircraft Larger Dynamic Doppler's quick capturing method, which is characterized in that the hypersonic flight Device Larger Dynamic Doppler quick capturing method the following steps are included:
The first step estimates doppler changing rate using quick blind estimating method；
Second step compensates the doppler changing rate in received IF signal；
Third step scans for the spectrum peak of signal after compensation according to the modified thought of spectrum peak search range, in conjunction with more General Le change rate blind estimate result realizes Doppler shift and doppler changing rate joint acquisition.
2. hypersonic aircraft Larger Dynamic Doppler's quick capturing method as described in claim 1, which is characterized in that described The quick blind estimating method of doppler changing rate includes: in the first step
(1) quadravalence for receiving signal is obtained away from slice: being received signal and is expressed asT >=0, In, a indicates the symbol amplitude of constant value, and b ∈ { -1 ,+1 } is unknown transmitted bit information, transmission rate rb, fdIt indicates Doppler shift, faIndicate doppler changing rate,Indicate signal initial phase, it is σ that n (t) expression mean value, which is 0 variance,2Answer Additive white Gaussian noise, the quadravalence for receiving signal are indicated away from slice are as follows:
τ in formula0It is fixed, and τ is variable, and τ0>0；
(2) quadravalence for receiving signal is obtained away from slice mrThe quadravalence of (τ) and the bit information in reception signal is away from slice mb(τ) it Between phase difference, indicate are as follows:
(3) discrete time Fourier transform is carried out to phase difference ξ (τ), obtained:
(4) estimated value of doppler changing rate is obtained by spectrum peak search
3. hypersonic aircraft Larger Dynamic Doppler's quick capturing method as described in claim 1, which is characterized in that described Received IF signal is compensated using the Doppler rate of estimation in second step, the difference frequency signal after compensating indicates are as follows:
In formulaFor remaining Doppler rate after compensation.
4. hypersonic aircraft Larger Dynamic Doppler's quick capturing method as described in claim 1, which is characterized in that described Third step includes:
(1) Fourier transformation is done to data of the result after compensation on m-th of symbol, as a result indicates are as follows:
T in formulab=1/rbIndicate the duration of a symbol, h (t) indicates the rectangular window in (m-1) T to mT time, N (f) table Show the Fourier transformation of noise item n (t)；
(2) Fourier transformation is done to data of the result after compensation on multiple continuous symbols, and carries out cumulative mean；
(3) power spectrum will obtain maximum value at true Doppler shift；
(4) range that Doppler shift generation is determined based on flight condition, is modified spectrum peak search range；
(5) spectrum peak search are carried out within the scope of the spectrum peak search after amendment, obtain Doppler shift.
5. hypersonic aircraft Larger Dynamic Doppler's quick capturing method described in a kind of application Claims 1 to 4 any one Aircraft.
6. hypersonic aircraft Larger Dynamic Doppler's quick capturing method described in a kind of application Claims 1 to 4 any one Wireless communication system.
Technical field
The invention belongs to wireless communication technology field more particularly to a kind of hypersonic aircraft Larger Dynamic Doppler are quick Catching method and communication system.
Background technique
Telemetry communication carrier signal can undergo the influence of Larger Dynamic Doppler during hypersonic aircraft maneuvering flight, And since ground control station snr of received signal is low, make it difficult to carrier signal in low signal-to-noise ratio, Larger Dynamic Doppler's item Capture fast and accurately is completed under part.
Currently, the immediate prior art: foreign scholar Falletti E is based on traditional carrier frequency and symbol phases Two-dimensional search algorithm, propose a kind of Doppler-frequency estimation more accurate than two-dimensional search algorithm using cross-ambiguity function Method, using the value Combined estimator Doppler frequency near cross-ambiguity function peak value, to obtain higher estimated accuracy, still It is only applicable to the higher situation of snr of received signal, and is primarily directed to fixed Doppler shift, and does not examine sufficiently Consider the influence of doppler changing rate.Domestic scholars Zhang Zhaowei is asked for the Larger Dynamic Doppler capture faced in deep space communication Topic proposes a kind of Doppler shift catching method based on spectrum peak search range amendment (SRC), catches from Doppler shift is improved The angle for obtaining probability improves the acquisition performance of carrier signal, but the method does not fully consider asking for Doppler's acquisition speed Topic.
For the acquisition speed problem of Doppler shift, domestic scholars Guo Wen flies to be based on partial matched filter (PMF-FFT) A kind of improved method is proposed, improves the estimation range of Doppler frequency while not increasing FFT points.Wang Le proposes to utilize The relationship amendment FFT of continuous two segment signals Fourier transformation improves Doppler frequency to the evaluated error of Doppler shift Estimated accuracy.However, the only fixed Doppler shift that the above-mentioned catching method based on FFT is directed to, and do not consider due to letter The opposite influence for accelerating caused doppler changing rate to acquisition performance of number transmitting terminal and receiving end.
In conclusion under conditions of both low signal-to-noise ratio, Larger Dynamic Doppler exist simultaneously, while considering carrier signal The rapidity of Doppler shift capture and when accuracy two indices, does not have very good solution method still at present, and Gao Chaosheng The capture of carrier signal under fast flight environment of vehicle is exactly exactly such a problem, it is therefore necessary at the same consider low signal-to-noise ratio and The simultaneous critical conditions of both Larger Dynamic Doppler study the fast, accurately catching method of carrier signal, for guaranteeing The round-the-clock continuous reliable telemetry communication of hypersonic aircraft is of great significance.
In conclusion problem of the existing technology is: under conditions of low signal-to-noise ratio, Larger Dynamic Doppler exist simultaneously Acquisition speed can be led to the problem of and acquisition accuracy is conflicting, and then lead to not realize that the quick of carrier signal accurately catches It obtains.
Solve the difficulty of above-mentioned technical problem:
Under Low SNR, a spectrum peak received on symbol is easy to be flooded by ambient noise to lead to spectrum peak It is difficult to detect.It is thus typically necessary to combine multiple symbols to obtain higher signal-to-noise ratio output in receiving end, to just can guarantee It is reliably communicated between aircraft and tracking telemetry and command station.It is spread however, Larger Dynamic Doppler will lead to signal energy in frequency domain, serious shadow Ring the energy accumulation of signal.In addition to this, the dynamic of Doppler can make Doppler frequency shift real-time compensation become highly difficult.Greatly Between dynamic Doppler acquisition accuracy and acquisition speed because both of the aforesaid constraint condition and there are serious contradictory problems.
Solve the meaning of above-mentioned technical problem:
The capture of hypersonic aircraft Larger Dynamic Doppler fast and accurately is realized, for solving hypersonic aircraft It is quick/real-tune TT & C communication problem be of great significance.
Summary of the invention
In view of the problems of the existing technology, the present invention provides a kind of hypersonic aircraft Larger Dynamic Doppler is quick Catching method and communication system.
The invention is realized in this way a kind of supersonic aircraft Larger Dynamic Doppler's quick capturing method, the ultrasound Fast aircraft Larger Dynamic Doppler quick capturing method the following steps are included:
The first step estimates doppler changing rate using quick blind estimating method；
Second step compensates the doppler changing rate in received IF signal；
Third step scans for the spectrum peak of signal after compensation according to the modified thought of spectrum peak search range, knot It closes doppler changing rate blind estimate result and realizes Doppler shift and doppler changing rate joint acquisition；
(1) Fourier transformation is done to data of the result after compensation on m-th of symbol, as a result: indicating are as follows:
T in formulab=1/rbIndicate the duration of a symbol, h (t) indicates the rectangular window in (m-1) T to mT time, N (f) Fourier transformation of noise item n (t) is indicated；
(2) Fourier transformation is done to data of the result after compensation on multiple continuous symbols, and carries out cumulative mean；
(3) power spectrum will obtain maximum value at true Doppler shift；
(4) range that Doppler shift generation is estimated based on flying condition, is modified spectrum peak search range；
(5) spectrum peak search are carried out within the scope of the spectrum peak search after amendment, obtain Doppler shift.
Further, the quick blind estimating method of doppler changing rate includes: in the first step
(1) quadravalence for receiving signal is obtained away from slice: being received signal and is expressed ast≥ 0, wherein a indicates the symbol amplitude of constant value, and b ∈ { -1 ,+1 } is unknown transmitted bit information, transmission rate rb, fd Indicate Doppler shift, faIndicate doppler changing rate,Indicate signal initial phase, it is σ that n (t) expression mean value, which is 0 variance,2 Multiple additive white Gaussian noise, receive the quadravalence of signal indicates away from slice are as follows:
τ in formula0It is fixed, and τ is variable, and τ0>0；
(2) quadravalence for receiving signal is obtained away from slice mrThe quadravalence of (τ) and the bit information in reception signal is away from slice mb Phase difference between (τ) indicates are as follows:
(3) discrete time Fourier transform is carried out to ξ (τ), obtained:
(4) estimated value of doppler changing rate is obtained by spectrum peak search
Further, received IF signal is compensated using the Doppler rate of estimation in the second step, compensates it Difference frequency signal afterwards indicates are as follows:
In formulaFor remaining Doppler rate after compensation.
Another object of the present invention is to provide a kind of application supersonic aircraft Larger Dynamic Doppler's fast Acquisitions The aircraft of method.
Another object of the present invention is to provide a kind of application supersonic aircraft Larger Dynamic Doppler's fast Acquisitions The wireless communication system of method.
In conclusion advantages of the present invention and good effect are as follows: the present invention is based on power spectrum spectrum peak search range is modified Thought is greatly improved Doppler shift and Doppler's variation in combination with doppler changing rate blind estimate and precompensation method The speed of the joint acquisition of rate.
The present invention compared with prior art, has the following beneficial effects:
1) can be achieved Ka frequency range (30GHz) under the conditions of Doppler shift 1.5MHz, doppler changing rate ± 200kHz at Function capture, and Doppler shift capture error, within 100Hz, doppler changing rate captures error within 1kHz.
2) when snr of received signal (SNR) is respectively equal to -34dB and -32dB, the acquisition probability difference of Doppler shift 0.56 and 0.92 have been increased to from 0.34 and 0.62.
3) when combined symbols number is 1000, capture processing speed is compared matched more parallel based on Doppler rate Road catching method improves 75.47%, and the promotion effect of processing speed becomes increasingly with the increase of combined symbols number Obviously.
Detailed description of the invention
Fig. 1 is supersonic aircraft Larger Dynamic Doppler quick capturing method flow chart provided in an embodiment of the present invention.
Fig. 2 is supersonic aircraft Larger Dynamic Doppler quick capturing method implementation process provided in an embodiment of the present invention Figure.
Fig. 3 is Doppler rate estimated result schematic diagram provided in an embodiment of the present invention.
Fig. 4 is the acquisition probability of Doppler shift on a symbol provided in an embodiment of the present invention with snr of received signal The curve synoptic diagram of variation.
Fig. 5 is the acquisition probability of doppler changing rate on a symbol provided in an embodiment of the present invention with reception signal noise Than the curve synoptic diagram of variation.
The acquisition probability of Doppler shift is believed with reception when Fig. 6 is 100 combined symbols numbers provided in an embodiment of the present invention The curve synoptic diagram of number signal-to-noise ratio variation.
The acquisition probability of doppler changing rate is with reception when Fig. 7 is 100 combined symbols numbers provided in an embodiment of the present invention The curve synoptic diagram of Signal-to-Noise variation.
Specific embodiment
In order to keep the objectives, technical solutions, and advantages of the present invention clearer, with reference to embodiments, the present invention is carried out It is further described.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to limit The present invention.
In view of the problems of the existing technology, the present invention provides a kind of hypersonic aircraft Larger Dynamic Doppler is quick Catching method and communication system, are with reference to the accompanying drawing explained in detail the present invention.
As shown in Figure 1, supersonic aircraft Larger Dynamic Doppler's quick capturing method provided in an embodiment of the present invention includes Following steps:
S101: blind Fast Estimation Algorithm is taken quickly to estimate the Doppler rate for receiving signal；
S102: the Doppler rate obtained using estimation is compensated to signal is received, for compensated reception signal Fourier transformation is carried out on multiple continuous symbols；
S103: square cumulative mean is carried out to the result of multiple symbol Fourier transformations；
S104: carrying out peak value searching to accumulation results, and wherein peak-peak is the Doppler shift value captured.
Technical scheme of the present invention will be further described with reference to the accompanying drawing.
As shown in Fig. 2, supersonic aircraft Larger Dynamic Doppler's quick capturing method provided in an embodiment of the present invention is specific The following steps are included:
The first step estimates doppler changing rate using quick blind estimating method；
Second step compensates the doppler changing rate in received IF signal；
Third step scans for the spectrum peak of signal after compensation according to the modified thought of spectrum peak search range, knot It closes doppler changing rate blind estimate result and realizes Doppler shift and doppler changing rate joint acquisition.
In a preferred embodiment of the invention, the quick blind estimating method of doppler changing rate includes in the first step,
(1) quadravalence for receiving signal is obtained away from slice: being received signal and is expressed ast≥ 0, wherein a indicates the symbol amplitude of constant value, and b ∈ { -1 ,+1 } is unknown transmitted bit information, transmission rate rb, fd Indicate Doppler shift, faIndicate doppler changing rate,Indicate signal initial phase, it is σ that n (t) expression mean value, which is 0 variance,2 Multiple additive white Gaussian noise.The quadravalence for receiving signal may be expressed as: away from slice
τ in formula0It is fixed, and τ is variable, and τ0>0。
(2) quadravalence for receiving signal is obtained away from slice mrThe quadravalence of (τ) and the bit information in reception signal is away from slice mb Phase difference between (τ), may be expressed as:
(3) discrete time Fourier transform is carried out to ξ (τ), can be obtained:
(4) estimated value of doppler changing rate is obtained by spectrum peak search
In a preferred embodiment of the invention, received IF signal is carried out using the Doppler rate of estimation in second step Compensation, the difference frequency signal after compensating can indicate are as follows:
In formulaFor remaining Doppler rate after compensation.
In a preferred embodiment of the invention, third step is according to the modified thought of spectrum peak search range to signal after compensation Spectrum peak scans for, to complete the joint acquisition of Doppler shift and doppler changing rate comprising following steps:
(1) Fourier transformation is done to data of the result after compensation on m-th of symbol, as a result may be expressed as:
T in formulab=1/rbIndicate the duration of a symbol, h (t) indicates the rectangular window in (m-1) T to mT time, N (f) Fourier transformation of noise item n (t) is indicated；
(2) Fourier transformation is done to data of the result after compensation on multiple continuous symbols, and carries out cumulative mean；
(3) range that Doppler shift generation is estimated based on flying condition, is modified spectrum peak search range；
(4) spectrum peak search are carried out within the scope of the peak value searching after amendment to the result of cumulative mean；
(5) peak-peak searched is the Doppler shift value that captures, and Doppler rate passed through it is above-mentioned Blind estimate algorithm obtains.
Technical effect of the invention is explained in detail below with reference to emulation.
1. simulated conditions and relative parameters setting:
The sample frequency of telemetry communication carrier signal is fc=30GHz, the radial phase between aircraft and ground control station It is v to movement velocitymax=15.0km/s, the diametrically acceleration of motion between aircraft and ground control station are va=204 ×9.8m/s2, the sample frequency for receiving signal is fs=6MHz, Doppler shift fd=1.5MHz, doppler changing rate fa =200kHz/s, the bit rate for transmitting symbol is rb=10.0kb/s, the detection threshold of Doppler shift is 100Hz, how general The detection threshold for strangling rate is 1kHz, and snr of received signal range is [- 42, -20] dB.Flying condition are as follows: aircraft and ground Diametrically movement velocity between the tracking telemetry and command station of face is from 5km/s with relative constant 204 × 9.8m/s of acceleration2Change to 25km/ S, at this point, the Doppler shift range of corresponding Spacecraft TT&C signal of communication is [0.5MHz, 2.5MHz].Therefore, in this hair Bright spectrum peak search link, can be by spectrum peak search scope limitation at [0.5MHz, 2.5MHz], rather than [- fs/ 2, fs/ 2]= [- 3MHz, 3MHz].
2. emulation content
Emulation 1, snr of received signal are equal to -20dB, and the quick blind estimate of the Doppler rate proposed through the invention is calculated Method is estimated to obtain the doppler changing rate for receiving signal.
As it is clear from fig. 2 that receiving the doppler changing rate of signal, i.e., the frequency component of 200kHz shown in Fig. 3 can pass through This blind estimate algorithm is accurately estimated.
Emulation 2 is respectively adopted based on the matched parallel multiple branch circuit catching method of Doppler rate and proposed by the invention Catching method scans for the spectrum peak of a symbol, and the acquisition probability for obtaining Doppler shift is believed with signal is received It makes an uproar than the curve of (SNR) variation.
As seen from Figure 4, after Doppler rate Fast Blind algorithm for estimating auxiliary, the acquisition performance of Doppler shift is obtained Improvement is arrived.
Emulation 3 is respectively adopted based on the matched parallel multiple branch circuit catching method of Doppler rate and proposed by the invention Catching method scans for the spectrum peak of a symbol, and the acquisition probability for obtaining Doppler rate is believed with signal is received It makes an uproar than the curve of (SNR) variation.
From figure 5 it can be seen that under conditions of snr of received signal is equal to -20dB, the acquisition probability of Doppler rate from 0.52 has been increased to 0.86.It, only can be real on a symbol using algorithm proposed by the invention and as SNR >=- 18dB The successful capture of existing Doppler rate 100%, this greatly accelerates the acquisition speed of carrier signal.
Emulation 4 is respectively adopted based on the matched parallel multiple branch circuit catching method of Doppler rate and proposed by the invention Catching method carries out cumulative mean to the power spectrum of 100 continuous symbols, then carries out peak value searching, obtain Doppler shift The curve that changes with snr of received signal (SNR) of acquisition probability.
As seen from Figure 6, when carrying out cumulative mean using 100 continuous symbols, catching method needle proposed by the invention The matched parallel multiple branch circuit catching method of Doppler rate is better than to the acquisition performance of Doppler shift.For example, when SNR respectively etc. When -34dB and -32dB, the acquisition probability of Doppler shift has been increased to 0.56 and 0.92 from 0.34 and 0.62 respectively.But As signal-to-noise ratio extremely low (SNR≤- 36dB), the acquisition probability of Doppler shift is promoted unobvious.
Emulation 5 is respectively adopted based on the matched parallel multiple branch circuit catching method of Doppler rate and proposed by the invention Catching method carries out cumulative mean to the power spectrum of 100 continuous symbols, then carries out peak value searching, obtain Doppler rate The curve that changes with snr of received signal (SNR) of acquisition probability.
From fig.7, it can be seen that when carrying out cumulative mean using 100 continuous symbols, catching method needle proposed by the invention The matched parallel multiple branch circuit catching method of Doppler rate is better than to the acquisition performance of Doppler rate, but when signal-to-noise ratio is extremely low When (SNR≤- 36dB), the acquisition probability of Doppler rate is equally promoted unobvious.The blind estimate algorithm of this Doppler rate In Arctic ice area, adaptability is limited, causes Doppler rate acquisition probability under the conditions of Arctic ice area to improve unknown It is aobvious.
Emulation 6, in same simulated environment, respectively for based on the matched multiple branch circuit parallel capture side of Doppler rate Method and catching method proposed by the invention, in snr of received signal SNR=-34dB, in various combination symbol said conditions Under the acquisition probability and acquisition speed of carrier signal are assessed simultaneously, obtain the capture of both carrier signal catching methods Probability and acquisition speed.
As seen from Table 1, for acquisition probability, when combined symbols number is respectively 100,300 and 500, base is compared Distinguish in the acquisition probability of the matched parallel multiple branch circuit catching method of Doppler rate, joint acquisition method proposed by the invention It is promoted from 0.34,0.82 and 0.91 to 0.56,0.88 and 0.94.And from the point of view of capture processing speed, the present invention is mentioned Catching method out will be better than based on the matched parallel multiple branch circuit capture of Doppler rate under the conditions of various combination symbolic number Method.In addition, after Doppler rate blind estimate algorithm auxiliary, processing speed is mentioned when combined symbols number is 1000 75.47% is risen, and the promotion effect of processing speed becomes to be more and more obvious with the increase of combined symbols number.
Table 1
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention Made any modifications, equivalent replacements, and improvements etc., should all be included in the protection scope of the present invention within mind and principle.
- 上一篇：一种医用注射器针头装配设备
- 下一篇：中继线缆及增强现实系统