CN101034899B - Civil aviation ground-air communication self-adaptive disturbance restraining method based on the single channel and its system - Google Patents
Civil aviation ground-air communication self-adaptive disturbance restraining method based on the single channel and its system Download PDFInfo
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Abstract
The invention relates to civil aviaton groud air communication self-adapting interference suppression method and its thesystem based on the single channel, including: translate the aerial wire received high frequency amplitude modulation signal into the medium frequency digital signal; and carries on medium frequency estimate after filter drawoff; carries on self-adapting trapped wave to trap the carrier wave in the amplitude modulation signal; thus carries on the orthogonal transform; taking the lasting model interference signal after the orthogonal transform; implement cancellation and carries on demodulation, again output the aural signal after filter the high frequency clutter. The invention considered the interference source characteristic of the civil aviaton groud air communication and the actual question, with the existing broadcasting station structure, does not increase the receiving antenna, does not use any reference signal, uses the self-adapting signal processing method can cancel the exterior permanent mold disturbance of serious influence broadcasting station receptivity, provided the anti-jamming ability of the civil aviaton groud air communication.Tend to maintain and to promote. Also may use in other amplitude-modulation receivers, enhances the receptivity.
Description
Technical field
The present invention relates to a kind of single channel self-adapting interference suppression method that is used for civil aviation air-ground communication.Particularly relate to and a kind ofly meet existing civil aviation air-ground communication system, realize simple and performance excellent, can improve communication quality, strengthen the flight safety coefficient based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method and system thereof.
Background technology
According to ICAO Treaty's annex 10 I volume regulation, aloft in the traffic control, the contact between ground controller and the airflight person mainly relies on VHF (very high frequency(VHF)) ground-to-plane radio to carry out, and it adopts the working method of AM (amplitude modulation).The advantage of amplitude modulation is that band occupancy is narrow, saves frequency resource, and hardware realizes that easily therefore early stage International Civil Aviation Organization is with its standard as the earth-space communication modulation system.Though the background noise of AM receiver is very low in earth-space communication, the poor anti jamming capability of AM receiver, and existing VHF ground-air communication equipment is not all considered anti-interference problem.
Especially, along with the fast development in recent years of China Telecom's cause, the disturbed degree of civil aviaton's communication frequency is more and more serious, aviation safety has been constituted serious hidden danger.With regard to interference source, mainly contain paging centers's transmitter, high-power cordless telephone, rural f-m broadcast station, vehicle radio station etc.These interference sources all have constant modulus property, and generally only there is an interference in the same time, its signal has illegally occupied the VHF of civil aviaton communications band, caused on frequency domain aliasing to AM useful signal frequency spectrum, the simple band pass filter that uses can not be with its filtering, so existing VHF ground-air communication equipment is subjected to disturbed condition serious.
In the disturbance restraining method of announcing at present, in the prospectus of patent application CN200410075232, mentioned the method and apparatus that suppresses disturbing pulse at AM receiver, specifically with disturbing pulse blanking from amplitude-modulated signal, after blanking, amplitude-modulated signal is carried out demodulation, carry out smooth amplitude-modulated signal remaining after the blanking.But this not too is fit to solve the problem of civil aviaton's Communication Jamming just at the impulse disturbances of short time.
Adaptive disturbance inhibition technology is that Adaptive Suppression is fallen interference signal or interference signal is carried out very large decay, improves signal interference ratio.In the disturbance restraining method of announcing at present, generally need two or more transducers to realize, the mixed signal of sensor acquisition useful signal and noise, the signal that other sensor acquisition is relevant with noise.This uses the single antenna signal reception mode to conflict mutually with existing VHF ground-to-plane radio, is difficult to directly use existing technology and method.
Summary of the invention
Technical problem to be solved by this invention is, provide a kind of and meet existing civil aviation air-ground communication system, realize simple and performance excellent, can improve communication quality, strengthen the flight safety coefficient based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method and system thereof.
The technical solution adopted in the present invention is: a kind of based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method and system thereof, wherein method includes following steps: (1) will be converted into intermediate-freuqncy signal by the very high frequency(VHF) amplitude-modulated signal that antenna receives; (2) intermediate-freuqncy signal that is transformed is carried out digital translation, filtering extraction; (3) on the known basis of amplitude-modulated signal carrier frequency frequency range, the signal behind the filtering extraction is carried out carrier frequency estimate; (4) with the carrier frequency frequency estimation as the reference signal, carry out adaptive notch, carrier wave in the amplitude-modulated signal is fallen into, catch phenomenon thereby avoid constant modulus algorithm to occur disturbing, the adaptive notch filter input signal has: the digital signal s (n) and the carrier frequency of filtering extraction output are estimated output valve f
KmaxThe carrier signal y (n) of adaptive notch filter output sends into demodulation module, is used for demodulation; (5) signal of removing modulated subcarrier technique is carried out orthogonal transform; (6) utilize constant modulus algorithm to extract permanent mould interference signal to the signal after the orthogonal transform; (7) with the input of the signal after the orthogonal transform in the step (5) as adaptive interference canceller, the permanent mould interference signal of extracting in the step (6) is sent into together and is implemented adaptive cancellation in the adaptive interference canceller as the Expected Response of adaptive interference canceller; (8) signal of step (7) adaptive interference canceller output is got real part, the carrier signal of exporting with step (4) multiplies each other, and carries out demodulation, again output audio signal behind low pass filter filters out high frequency clutter.
Describedly the very high frequency(VHF) amplitude-modulated signal is converted into intermediate-freuqncy signal is undertaken by low noise high-frequency amplifier, three grades of frequency mixers and automatic gain control circuit.
The described intermediate-freuqncy signal that quilt is transformed is carried out digital translation, filtering extraction, is to collection of analog if signal implementation data and analog-to-digital conversion by the A/D conversion.Describedly signal behind the filtering extraction is carried out carrier frequency estimating, is to utilize the Goertzel algorithm to carry out carrier frequency to estimate.
Described signal to the removal modulated subcarrier technique carries out orthogonal transform, is that the error signal of trapper output is carried out orthogonal transform, and real signal is transformed into complex signal.
The described constant modulus algorithm that utilizes extracts permanent mould interference signal, is to adopt simple normalization to carry out to the complex signal after the conversion.
Of the present invention based on single pass civil aviation ground-air communication self-adaptive Interference Suppression System, the antenna, radio-frequency front-end unit, A/D converter, the adaptive disturbance that include successively suppress platform, D/A switch unit and audio output unit; Described adaptive disturbance suppresses platform and includes: the filtering extraction module that links to each other with described A/D converter; Adaptive notch filter that links to each other with the filtering extraction module and carrier frequency estimation module respectively, adaptive notch filter also links to each other with the carrier frequency estimation module; The orthogonal transform module that links to each other with adaptive notch filter; Constant modulus algorithm module and the adaptive interference canceller that links to each other with the orthogonal transform module respectively, the constant modulus algorithm module also links to each other with adaptive interference canceller; The demodulation module that links to each other with adaptive notch filter and adaptive interference canceller respectively, the output of described demodulation module connects the D/A converting unit.
Described radio-frequency front-end unit includes: the low noise amplifier of Xiang Lianing successively, the first bandpass filtering amplifying circuit, the one-level mixting circuit, the second bandpass filtering amplifying circuit, the secondary mixting circuit, the 3rd bandpass filtering amplifying circuit, voltage-controlled attenuator, intermediate level circuit, three grades of mixting circuits, four-tape pass filter amplifying circuit, the one-level mixting circuit also connects the first frequency synthesizer, the secondary mixting circuit also connects the second frequency synthesizer, the first frequency synthesizer also is connected crystal oscillating circuit respectively with the second frequency synthesizer, the output of intermediate level circuit also connects detecting circuit, detecting circuit also links to each other with voltage-controlled attenuator by comparator, and three grades of mixting circuits also connect three local oscillation circuits.
Of the present invention based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method and system thereof, the interference source characteristic that the has taken into full account civil aviation air-ground communication practical problem of communicating by letter with civil aviaton, the self adaptation single channel constant-mould interference rejection method that proposes, improved the antijamming capability of civil aviation air-ground communication system, and be easy to safeguard and upgrading.The present invention is based on existing broadcasting station structure, need not increase reception antenna; Need not use any reference signal, the employing adaptive signal processing method can offset the outside permanent mould that has a strong impact on the radio station receptivity and disturb.By to mixed signal elder generation trap, utilize constant modulus algorithm to carry out permanent mould again and disturb extraction, not only avoid the interference of constant modulus algorithm to catch phenomenon well, and computing is simple, real-time is good.The present invention also when improving the civil aviation air-ground communication interference free performance, does not increase considerably the hardware cost of whole communication station, is easy to safeguard and upgrading.Method of the present invention also can be used in other AM receiver, improves receptivity, and practical, cost is low, and market application foreground is wide.
Description of drawings
Fig. 1 is the civil aviation ground-air communication self-adaptive Interference Suppression System;
Fig. 2 is the radio-frequency front-end composition frame chart;
Fig. 3 is that adaptive disturbance suppresses platform;
Fig. 4 is a Goertzel algorithm recursion flow chart;
Fig. 5 is an adaptive notch filter;
Fig. 6 is the orthogonal transform module;
Fig. 7 is an adaptive interference canceller;
Fig. 8 a is former voice signal oscillogram;
Fig. 8 b is the voice signal oscillogram of demodulation after adaptive disturbance suppresses;
The voice signal oscillogram of the direct demodulation of Fig. 8 c mixed signal.
Embodiment
Describe in detail the present invention is based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method and system thereof with specific embodiment with reference to the accompanying drawings.
For the present invention being done further understanding, the technical characteristic below in conjunction with the VHF of civil aviaton (very high frequency(VHF)) ground-to-plane radio gives detailed introduction to specific implementation process of the present invention.
The technical characteristic of relevant VHF earth-space communication device has been done specified in more detail in international convention annex 10 I volume.The working method of DSB-AM (band carrier wave double-sideband amplitude modulation), half-duplex operation is adopted in the radio station, its operating frequency range is 118.0MHz to 136.975MHz, channel spacing is 25KHz, and 760 communication channels can be provided, and these channels can be used in wide region again.
For this reason, of the present invention based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method, be to utilize shown in Figure 1 to realize that based on single pass civil aviation ground-air communication self-adaptive Interference Suppression System specific practice is as follows:
The first step will be converted into intermediate-freuqncy signal by the very high frequency(VHF) amplitude-modulated signal that antenna receives.At first, make the civil aviation air-ground communication amplitude-modulated signal that the disturbed radio-frequency front-end by as shown in Figure 2, radio-frequency front-end is made up of low-noise high-frequency amplifier, three grades of frequency mixers and automatic gain control circuit (empty frame part among Fig. 2), radio signal is converted into the 1.25MHz intermediate-freuqncy signal after by radio-frequency front-end, so that follow-up signal is handled.
In the present embodiment, circuit such as described low-noise high-frequency amplifier, three grades of frequency mixers and automatic gain control circuit are realized by existing circuit or principle.Three grades of intermediate frequencies that obtain after three grades of mixing are respectively 465MHz, 70MHz, 1.25MHz.
The adaptive disturbance that intermediate-freuqncy signal after the digitlization is passed through as shown in Figure 3 suppresses platform then, carries out each step described later.That is, utilize self-adapting interference suppression method of the present invention to be disturbed enforcement to suppress, improve signal interference ratio disturbing the permanent mould in the amplitude-modulated signal.Its adaptive disturbance suppresses platform and includes filtering extraction module, carrier frequency estimation module, adaptive notch filter, orthogonal transform module, CMA (constant modulus algorithm) module, adaptive interference canceller, demodulation module.Single permanent mould in the Adaptive Suppression civil aviation air-ground communication process disturbs, and improves signal interference ratio, strengthens the flight safety coefficient.
In second step, the intermediate-freuqncy signal that is transformed is carried out digital translation, filtering extraction.By the A/D converting unit analog if signal implementation data of radio-frequency front-end output is gathered and analog-to-digital conversion.In order to reduce to follow-up Design of Digital Filter requirement, adopted the scheme of over-sampling in the present embodiment, the actual sample rate of using is 5MHz, sampling resolution 12bit.In the filtering extraction module analog-to-digital conversion output digital signal is carried out filtering extraction, data transfer rate is dropped to suitable degree from 5MSps.Purpose is to improve real-time and reduce the operand that follow-up signal is handled.In the present embodiment, used the two-stage bandpass filtering to extract, extracted 5 times at every turn, last sample rate drops to 200KSps.
In the 3rd step, on the known basis of amplitude-modulated signal carrier frequency frequency range, the signal behind the filtering extraction is carried out carrier frequency estimate.Described carrier frequency estimates it is that the digital signal s (n) to the output of filtering extraction module utilizes the Goertzel algorithm to carry out the carrier frequency estimation in the carrier frequency estimation module, and purpose is to provide a frequency initial value f for adaptive notch filter
Kmax, to improve the convergence rate of trapper.
Wherein the Goertzel algorithm of carrier frequency estimation module employing is to utilize twiddle factor
Periodicity
DFT (discrete Fourier transform) operation table is shown as the linear filtering computing, and the form of calculus of differences makes that its recursion is better.Fig. 4 provides Goertzel algorithm recursion flow chart, and its recursive expression is:
In the present embodiment, the N in formula (1), the formula (2) gets 200K, and k is for needing the Frequency point in search rate interval, and the initial condition of formula (1) is made as v
k(1)=v
k(2)=0, n=0,1 ..., N
l, N
lGet N/10 (being 20K), s (n) is the digital signal of filtering extraction module output, output f
k(n) be the frequency spectrum of respective frequencies point k.Present embodiment adopts the idiographic flow of estimating based on Goertzel algorithm carrier frequency to be:
(1) at each Frequency point k, to n=0,1 ..., N
lIterative computation formula (1) is then at n=N
lCalculating formula (2), thus the frequency spectrum (in the present embodiment, Frequency point k is positioned at carrier frequency and estimates that initial value is that 50KHz is the frequency separation of center ± 500Hz, and L gets 101, i.e. 10Hz at interval between the Frequency point) of L Frequency point obtained;
(2) ask L Frequency point frequency spectrum f
k(N
l) the maximum corresponding Frequency point f of middle amplitude
Kmax(promptly to L f that puts
k(N
l) delivery, ask the maximum in these mould values), and with this carrier frequency estimated value f
KmaxFor renewal frequency interval in center is [f
Kmax-10Hz, f
Kmax+ 10Hz];
(3) frequency spectrum that uses new sampled data to restart L Frequency point to the frequency separation that upgrades calculates, and reaches N once more at sampled point
lThe time ask the maximum corresponding Frequency point f of amplitude in L the Frequency point frequency spectrum
Kmax, with the f that obtains this moment
KmaxFrequency initial value for adaptive notch filter.
The 4th step, as the reference signal, carry out adaptive notch with the carrier frequency frequency estimation, the carrier wave in the amplitude-modulated signal is fallen into, catch phenomenon thereby avoid constant modulus algorithm to occur disturbing.Described adaptive notch is to carry out in adaptive notch filter as shown in Figure 5, and its input signal has: the digital signal s (n) and the carrier frequency of filtering extraction output are estimated output valve f
Kmax, the output two paths of signals: the carrier signal y of output (n) sends into demodulation module, is used for demodulation.The error output signal e (n) of removing carrier wave connects the orthogonal transform module, converts thereof into complex signal, so that follow-up Adaptive Signal Processing.
The groundwork process of Fig. 5 adaptive notch filter is that the digital signal x (n) of filtering extraction output exports the error signal e (n) of removing carrier wave by iir filter:
e(n)＝x(n)+a(n)x(n-1)+x(n-2)-ra(n)e(n-1)+r
2e(n-2) (3)
Wherein a (n) is the trap parameter that needs adjustment, and it finally converges to-2cos ω
0, be positioned at frequencies omega to fall into to remove
0Modulated subcarrier technique, r is the polar radius of trapper, should be slightly less than 1, gets 0.99995 in the present embodiment.
For the update algorithm of a (n), shilling
Be that formula (3) is asked local derviation to a (n):
g(n)＝x(n-1)-re(n-1)-ra(n)g(n-1)+r
2g(n-2) (4)
Use the LMS algorithm, get the more new formula of a (n):
a(n+1)＝a(n)-2μe(n)g(n) (5)
The corresponding carrier wave y (n) that traps out is:
y(n)＝x(n)-e(n) (6)
In the formula (5), 0≤μ≤1 is a step-length, and a (0) is the carrier estimation value.
By above derivation, present embodiment adopts the adaptive notch algorithm steps as follows:
(1) initialization: g (0)=g (1)=0, e (0)=e (1)=0, r=0.99995, μ=0.0001, a (0) is obtained by the output valve of carrier frequency estimation module, promptly-2cos (2 π f
Kmax);
(2) calculating formula (3) and formula (4) obtain removing the error signal e (n) of carrier wave;
(3) calculating formula (5) and formula (6) are carried out coefficient update and outgoing carrier y (n), repeating step 2 and step 3.
In the 5th step, the signal of removing modulated subcarrier technique is carried out orthogonal transform.Described orthogonal transform is to carry out in orthogonal transform module as shown in Figure 6, and the error signal e (n) of trapper output is carried out orthogonal transform, and real signal is transformed into complex signal e
1(n), the e that draws
1(n) send into CMA (constant modulus algorithm) module and adaptive interference cancellation module.
FIRQ among Fig. 6 is a Hilbert filter, and its coefficient satisfies:
In the formula (7), M is a filter order, and w (k) is the Blackman window, satisfies following formula:
w(k)＝0.42-0.5cos(2πk/(M+2))+0.08cos(4πk/(M+2)) (1≤k≤M+1) (8)
FIRI among Fig. 6 is a delayer, M/2 the unit of delaying time, and M gets 88 in the present embodiment.
The error signal e (n) of trapper output forms in-phase component e after by FIRI and FIRQ
1I(n) and quadrature component e
1Q(n), be merged into complex signal e at last
1(n):
e
1(n)＝e
1I(n)+j*e
1Q(n) (9)
In the 6th step, utilize constant modulus algorithm to extract permanent mould interference signal to the signal after the orthogonal transform.Described CMA (constant modulus algorithm) is the complex signal e to orthogonal transform output
1(n) carry out permanent mould interference signal by the constant modulus property that disturbs and extract, for adaptive interference canceller provides reference signal.Consider the permanent model point of interference signal and be line-of-sight propagation, do not have the multipath composition, thus in the present embodiment to e
1(n) simple normalization obtains reference signal e
2(n), that is:
Compare with traditional CMA algorithm, the CMA algorithm that the present invention adopts is compared simpler, only is single channel, single time-delay joint, and be easy to realize, and do not have traditional C MA convergence of algorithm problem, only be simple normalization step.
In the 7th step, with the input of the signal after the orthogonal transform in the step 5 as adaptive interference canceller, the permanent mould interference signal of extracting in the step 6 is sent into together and is implemented in the adaptive interference canceller to offset as the Expected Response of adaptive interference canceller.Described adaptive interference cancellation is to carry out in adaptive interference canceller as shown in Figure 7, with the complex signal e of orthogonal transform module output
1(n) as desired signal, the permanent mould interference signal e of CMA module output
2(n) as with reference to signal, carry out weights study and renewal by adaptive algorithm, carry out adaptive cancellation, output signal u (n) send demodulation module.In the present embodiment, adaptive algorithm adopts the LMS algorithm, according to formula (11) and formula (12) iteration refreshing weight and calculating u (n):
u(n)＝e
1(n)-w
*(n)e
2(n) (11)
w(n+1)＝w(n)+μ
1e
2(n)u
*(n) (12)
In the present embodiment, the initial condition of formula (11) and formula (12) is made as: w (0)=0, μ
1=0.0001.
The 8th step, the signal of step 7 adaptive interference canceller output is got real part, the carrier signal of exporting with step 4 multiplies each other, and carries out demodulation, again output audio signal behind low pass filter filters out high frequency clutter.This step is to carry out in demodulation module, and its input signal has: the signal u (n) of the carrier signal y (n) of adaptive notch filter output, adaptive interference canceller output.In the present embodiment, multiply each other with y (n) after getting u (n) real part,, thereby be inhibited digital audio and video signals after disturbing through LPF (low pass filter) module filtering high frequency clutter.
The 9th step, adaptive disturbance is suppressed the digital audio and video signals that platform is exported, utilize D/A (D/A) converting unit to carry out digital-to-analogue conversion, with regard to exportable audio signal clearly.
Fig. 8 a, 8b, 8c have provided the effect contrast figure who has noiseless inhibition to handle.Wherein Fig. 8 a is former voice signal oscillogram, Fig. 8 b is the voice signal oscillogram of demodulation after adaptive disturbance suppresses, and Fig. 8 c is the voice signal oscillogram of the direct demodulation of mixed signal, as seen Fig. 8 b is more effective than Fig. 8 c, near former voice signal oscillogram, advantage of the present invention and practical value have been demonstrated fully.As seen, the present invention is simple and broken through traditional design concept, is easy to safeguard and upgrading that practical, market application foreground is wide.
As shown in Figure 1, of the present invention based on single pass civil aviation ground-air communication self-adaptive Interference Suppression System, the antenna 1, radio-frequency front-end unit 2, A/D (mould/number) converting unit 3, the adaptive disturbance that include successively suppress platform 4, D/A (D/A) converting unit 5 and audio output unit 6.
As shown in Figure 2, described radio-frequency front-end unit 2 includes: the LNA of Xiang Lianing (low noise amplifier) 14 successively, the one BPF (bandpass filtering) amplifying circuit 15, one-level mixting circuit 16, the 2nd BPF amplifying circuit 17, secondary mixting circuit 18, the 3rd BPF amplifying circuit 19, voltage-controlled attenuator 20, intermediate level circuit 21, three grades of mixting circuits 22, the 4th BPF amplifying circuit 23, one-level mixting circuit 16 also connects first frequency synthesizer 24, secondary mixting circuit 18 also connects second frequency synthesizer 25, first frequency synthesizer 24 also is connected crystal oscillating circuit 26 respectively with second frequency synthesizer 25, the output of intermediate level circuit 21 also connects detecting circuit 28, detecting circuit 28 also links to each other with voltage-controlled attenuator 20 by comparator 27, and three grades of mixting circuits 22 also connect three local oscillation circuits 29.
As Fig. 1, shown in Figure 3, described adaptive disturbance suppresses platform 4 and includes: the filtering extraction module 7 that links to each other with described A/D converter 3; Adaptive notch filter 8 that links to each other with filtering extraction module 7 and carrier frequency estimation module 11 respectively, adaptive notch filter 8 also links to each other with carrier frequency estimation module 11; The orthogonal transform module 9 that links to each other with adaptive notch filter 8; CMA (constant modulus algorithm) module 12 and the adaptive interference canceller 13 that link to each other with orthogonal transform module 9 respectively, CMA module 12 also links to each other with adaptive interference canceller 13; The demodulation module 10 that links to each other with adaptive notch filter 8 and adaptive interference canceller 13 respectively, the output of described demodulation module 10 connects D/A converting unit 5.
Claims (8)
1. one kind based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method, it is characterized in that, includes following steps:
(1) will be converted into intermediate-freuqncy signal by the very high frequency(VHF) amplitude-modulated signal that antenna receives;
(2) intermediate-freuqncy signal that is transformed is carried out digital translation, filtering extraction;
(3) on the known basis of amplitude-modulated signal carrier frequency frequency range, the signal behind the filtering extraction is carried out carrier frequency estimate;
(4) with the carrier frequency frequency estimation as the reference signal, carry out adaptive notch, carrier wave in the amplitude-modulated signal is fallen into, catch phenomenon thereby avoid constant modulus algorithm to occur disturbing, the adaptive notch filter input signal has: the digital signal s (n) and the carrier frequency of filtering extraction output are estimated output valve f
KmaxThe carrier signal y (n) of adaptive notch filter output sends into demodulation module, is used for demodulation;
(5) signal of removing modulated subcarrier technique is carried out orthogonal transform;
(6) utilize constant modulus algorithm to extract permanent mould interference signal to the signal after the orthogonal transform;
(7) with the input of the signal after the orthogonal transform in the step (5) as adaptive interference canceller, the permanent mould interference signal of extracting in the step (6) is sent into together and is implemented adaptive cancellation in the adaptive interference canceller as the Expected Response of adaptive interference canceller;
(8) signal of step (7) adaptive interference canceller output is got real part, the carrier signal of exporting with step (4) multiplies each other, and carries out demodulation, again output audio signal behind low pass filter filters out high frequency clutter.
2. according to claim 1 based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method, it is characterized in that, describedly the very high frequency(VHF) amplitude-modulated signal is converted into intermediate-freuqncy signal is undertaken by low noise high-frequency amplifier, three grades of frequency mixers and automatic gain control circuit.
3. according to claim 1 based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method, it is characterized in that, the described intermediate-freuqncy signal that quilt is transformed is carried out digital translation, filtering extraction, is to collection of analog if signal implementation data and analog-to-digital conversion by the A/D conversion.
4. according to claim 1ly it is characterized in that based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method, describedly signal behind the filtering extraction is carried out carrier frequency estimate, is to utilize the Goertzel algorithm to carry out carrier frequency to estimate.
5. according to claim 1 based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method, it is characterized in that, described signal to the removal modulated subcarrier technique carries out orthogonal transform, is that the error signal of trapper output is carried out orthogonal transform, and real signal is transformed into complex signal.
6. according to claim 1ly it is characterized in that based on single pass civil aviation ground-air communication self-adaptive disturbance restraining method the described constant modulus algorithm that utilizes extracts permanent mould interference signal, is to adopt simple normalization to carry out to the complex signal after the conversion.
7. one kind based on single pass civil aviation ground-air communication self-adaptive Interference Suppression System, it is characterized in that the antenna (1), radio-frequency front-end unit (2), A/D converter (3), the adaptive disturbance that include successively suppress platform (4), D/A switch unit (5) and audio output unit (6); Described adaptive disturbance suppresses platform (4) and includes: the filtering extraction module (7) that links to each other with described A/D converter (3); Adaptive notch filter (8) that links to each other with filtering extraction module (7) and carrier frequency estimation module (11) respectively, adaptive notch filter (8) also links to each other with carrier frequency estimation module (11); The orthogonal transform module (9) that links to each other with adaptive notch filter (8); Constant modulus algorithm module (12) that links to each other with orthogonal transform module (9) and adaptive interference canceller (13) respectively, constant modulus algorithm module (12) also links to each other with adaptive interference canceller (13); The demodulation module (10) that links to each other with adaptive notch filter (8) and adaptive interference canceller (13) respectively, the output of described demodulation module (10) connects D/A converting unit (5).
8. according to claim 7 based on single pass civil aviation ground-air communication self-adaptive Interference Suppression System, it is characterized in that, described radio-frequency front-end unit (2) includes: the low noise amplifier of Xiang Lianing (14) successively, the first bandpass filtering amplifying circuit (15), one-level mixting circuit (16), the second bandpass filtering amplifying circuit (17), secondary mixting circuit (18), the 3rd bandpass filtering amplifying circuit (19), voltage-controlled attenuator (20), intermediate level circuit (21), three grades of mixting circuits (22), four-tape pass filter amplifying circuit (23), one-level mixting circuit (16) also connects first frequency synthesizer (24), secondary mixting circuit (18) also connects second frequency synthesizer (25), first frequency synthesizer (24) also is connected crystal oscillating circuit (26) respectively with second frequency synthesizer (25), the output of intermediate level circuit (21) also connects detecting circuit (28), detecting circuit (28) also links to each other with voltage-controlled attenuator (20) by comparator (27), and three grades of mixting circuits (22) also connect three local oscillation circuits (29).
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| CN101174842B (en) * | 2007-09-25 | 2011-08-31 | 中国民航大学 | Single channel optimum constant-mould interference rejection method and system in civil aviation air-ground communication |
| CN101252364B (en) * | 2008-01-16 | 2011-06-15 | 中国民航大学 | New civil aviation ground and air communication twin channel constant module interference suppressing method and system |
| CN104168069B (en) * | 2014-08-12 | 2016-06-01 | 武汉邮电科学研究院 | The modulating system of phase controlled rotation in the coherent light communications field and modulator approach |
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