阅读说明：本技术 卫星通信地面站干扰防护装置及方法 (Satellite communication ground station interference protection device and method ) 是由 孟进 王青 何方敏 罗康 马伟明 李斌 杨凯 张嘉毫 刘宏波 董慷 于 2021-08-27 设计创作，主要内容包括：本发明涉及无线通信设备抗干扰技术领域,公开了一种卫星通信地面站干扰防护装置,包括取样天线阵列,取样天线阵列包括N个取样天线单元,N≥1,还包括N+1个第一级下变频模块、馈电馈钟模块、N+1个第二级下变频模块、N+1个模数转换模块、数字信号处理模块、数模转换模块、上变频模块和本振源模块。本发明还公开了一种卫星通信地面站干扰防护方法。本发明卫星通信地面站干扰防护装置及方法,能够与卫通地面站设备集成,且可全方位角覆盖,并具有更小的电路尺寸和更高的空间分辨率。(The invention relates to the technical field of anti-interference of wireless communication equipment, and discloses a satellite communication ground station interference protection device which comprises a sampling antenna array, wherein the sampling antenna array comprises N sampling antenna units, N is larger than or equal to 1, and the satellite communication ground station interference protection device also comprises N +1 first-stage down-conversion modules, a feed clock-feeding module, N +1 second-stage down-conversion modules, N +1 analog-to-digital conversion modules, a digital signal processing module, a digital-to-analog conversion module, an up-conversion module and a local vibration source module. The invention also discloses a satellite communication ground station interference protection method. The satellite communication ground station interference protection device and method can be integrated with satellite communication ground station equipment, can realize omnidirectional angular coverage, and have smaller circuit size and higher spatial resolution.)

1. A satellite communication ground station interference protector, its characterized in that: the sampling antenna array comprises N sampling antenna units (1), wherein N is more than or equal to 1, and the sampling antenna array also comprises N +1 first-stage down-conversion modules (2), a feed clock module (3), N +1 second-stage down-conversion modules (4), N +1 analog-to-digital conversion modules (5), a digital signal processing module (6), a digital-to-analog conversion module (7), an up-conversion module (8) and a first local vibration source module (9);

in the sampling antenna array, N sampling antenna units (1) are respectively connected with the input ends of second to (N +1) th first-stage down-conversion modules (2), and the sampling antenna units (1) collect interference signal samples from different spatial positions;

in the first-stage down-conversion module (2), the input end of the first-stage down-conversion module (2) is connected with the output end of a parabolic satellite antenna (10), the input ends of the other first-stage down-conversion modules (2) are connected with the sampling antenna unit (1), the output end of the first-stage down-conversion module (2) is respectively connected with the feed clock port of the feed clock module (3), and the first-stage down-conversion module (2) filters, amplifies low noise and down-converts radio frequency signals received by the satellite antenna (10) and the sampling antenna unit (1) into intermediate frequency;

the output end of each intermediate frequency signal in the feeding clock feeding module (3) is respectively connected with each input end of the second-stage down-conversion module (4), and the feeding clock feeding module (3) outputs a plurality of paths of intermediate frequency signals output by the first-stage down-conversion module (2) and provides power and reference clock signals for the first-stage down-conversion module (2);

each output end of the second-stage down-conversion module (4) is respectively connected with each input end of the analog-to-digital conversion module (5), and the second-stage down-conversion module (4) down-converts the intermediate frequency signals into baseband or lower intermediate frequency signals;

each output end of the analog-to-digital conversion module (5) is connected with the input end of the digital signal processing module (6), and the analog-to-digital conversion module (5) converts a received signal into a digital signal and inputs the digital signal to the digital signal processing module (6);

the output end of the digital signal processing module (6) is connected with the input end of the digital-to-analog conversion module (7), and the digital signal processing module (6) realizes interference suppression processing in a digital domain and outputs the processed digital signal;

the output end of the digital-to-analog conversion module (7) is connected with the input end of the upper frequency conversion module (8), and the digital-to-analog conversion module (7) converts the digital signal output by the digital signal processing module (6) into an analog baseband signal or an intermediate frequency signal;

the output end of the up-conversion module (8) is connected with a satellite communication modem (11), and the up-conversion module (8) up-converts the output signal of the digital-to-analog conversion module (7) to the intermediate frequency signal frequency of a satellite communication ground station and outputs the intermediate frequency signal frequency;

the output of the first local vibration source module (9) is connected with local vibration ports of the second-stage down-conversion module (4) and the up-conversion module (8), and the first local vibration source module (9) provides local vibration signals required by down-conversion and up-conversion, so that the signal frequency in output is the same as the frequency of received intermediate frequency signals.

2. The satellite communication ground station interference prevention apparatus of claim 1, wherein: the sampling antenna array is a distributed array antenna, each sampling antenna unit (1) of the sampling antenna array is annularly arranged around the satellite antenna (10), the main beam of each sampling antenna unit (1) points to the radial direction, the azimuth angle 3dB beam width theta az and the pitch angle 3dB beam width theta el of each sampling antenna unit are provided, the number of suppressible interference sources is K, and the satellite antenna side lobe maximum gain GS meets the following relation: 2 pi ∙ M/N is not less than theta az is not less than 4 pi ∙ M/(10Gs/10 ∙ theta el), wherein M = ⌊ N ∙ theta az/(2 pi) ⌋, K is not less than M is not less than N, and ⌊ ∙ ⌋ is a rounding-down operation.

3. The satellite communication ground station interference prevention apparatus of claim 1, wherein: the first-stage down-conversion module (2) comprises a preselection filter (21), a first low-noise amplifier (22), a mixer (23), an intermediate frequency band-pass filter (24), a first duplexer (25), a first bias device (26) and a second local oscillator module (27):

the input end of the preselection filter (21) is connected with the sampling antenna unit (1) or the satellite antenna (10), and the output end of the preselection filter is connected with the input end of the first low-noise amplifier (22) to filter signals outside a satellite frequency band;

the output end of the first low-noise amplifier (22) is connected with the radio-frequency input end of the mixer (23) and is used for carrying out low-noise amplification on a received signal;

the local oscillation input end of the frequency mixer (23) is connected with the output end of the second local oscillation source module (27), and the output end of the frequency mixer is connected with the input end of the intermediate frequency band-pass filter (24), so that frequency mixing down-conversion processing is realized;

the output end of the intermediate frequency band-pass filter (24) is connected with the intermediate frequency input end of the first duplexer (25) and is used for filtering image signals generated by mixing;

a common port of the first duplexer (25) is connected with the intermediate frequency and 10MHz reference composite radio frequency port of the first biaser (26), and a 10MHz output port is connected with a reference source port of the second local vibration source module (27) so as to realize multiplexing of intermediate frequency and 10MHz reference signals;

the intermediate frequency, 10MHz and DC power supply composite port of the first biaser (26) is connected with the feeding clock feeding port of the feeding clock feeding module (3), and the DC power port is connected with the power port of the second local oscillation source module (27) and the power port of the first low-noise amplifier (22) and is used for realizing the multiplexing of an intermediate frequency signal, a 10MHz reference signal and a DC power supply on the same interface;

the output end of the second local vibration source module (27) is connected with the local vibration signal input end of the frequency mixer (23) and used for generating local vibration signals required by frequency mixing, and the second local vibration source modules (27) have the same frequency and share the same reference clock source.

4. The satellite communication ground station interference prevention apparatus of claim 1, wherein: the sampling antenna array and the first-stage down-conversion module (2) are integrated and are installed on an antenna housing inner base of a sanitary ground station.

5. The satellite communication ground station interference prevention apparatus of claim 1, wherein: the feeding clock module (3) comprises N +1 second biasers (35), N +1 second duplexers (36), a power supply module (31), a multi-path power divider (32), a second low-noise amplifier (37) and a crystal oscillator (33), wherein:

the second biasers (35) each comprise a second biaser common terminal (351), a second biaser radio frequency terminal (352) and a second biaser direct current terminal (353), the second biaser common terminal (351) is connected with the intermediate frequency terminal of the first stage down-conversion module (2), the second biaser direct current terminal (353) is connected with the output terminal of the power supply module (31), and the second biaser radio frequency terminal (352) is connected with a second duplexer common terminal (361) of the second duplexer (36);

the second duplexers (36) respectively comprise a second duplexer common end (361), a second duplexer high-frequency end (362) and a second duplexer low-frequency end (363), the second duplexer high-frequency end (362) is connected with each input end of the second stage down-conversion module (2), the second duplexer low-frequency end (363) is connected with each output end of the multi-path power divider (32), and the intermediate frequency signal and the reference clock signal are transmitted in two directions at the same end;

the input end of the power supply module (31) is connected with an external power supply (34), and the output end of the power supply module is respectively connected with the direct current end (353) of each second biaser and the power supply end of the crystal oscillator (33) to supply power to the first-stage down conversion module (2) and the crystal oscillator (33);

the input end of the multi-path power divider (32) is connected with the output end of the second low-noise amplifier (37), and the output end of the multi-path power divider is respectively connected with the low-frequency end (363) of each second duplexer and is used for dividing the signal generated by the crystal oscillator (33) into N +1 paths of power;

the input end of the second low-noise amplifier (37) is connected with the output end of the crystal oscillator (33), the output end of the second low-noise amplifier is connected with the input end of the multi-path power divider (32), and signals generated by the crystal oscillator (33) are subjected to low-noise amplification;

the output end of the crystal oscillator (33) is connected with the input end of the second low-noise amplifier (37) to generate a clock signal which needs to be referred by the first-stage down-conversion module (2).

6. The satellite communication ground station interference prevention apparatus of claim 1, wherein: the ports of the first-stage down-conversion module (2) and the feeding clock-feeding module (3) are connected by cables, and the feeding clock-feeding module (3) and the second-stage down-conversion module (4) are connected by cables.

7. A satellite communication ground station interference protection method is characterized by comprising the following steps:

s1: installing the satellite communication ground station interference prevention device of claim 1;

s2: inputting the satellite antenna receiving signal and the sampling antenna unit receiving signal into a band-pass filter (12) to filter out the out-of-band interference signal and noise of the communication signal;

s3: inputting the filtered received signal of the sampling antenna unit into a nonlinear space-time beam former (13) to realize nonlinear transformation and obtain a sampling signal after the nonlinear transformation;

s4: carrying out linear weighted synthesis on the sampling signals after nonlinear transformation to obtain interference cancellation signals;

s5: synthesizing the interference cancellation signal and the filtered satellite communication antenna receiving signal to realize interference suppression;

s6: and adopting a self-adaptive filtering algorithm to iteratively adjust the weighted weight of the sampling signal so as to minimize the average power of the cancellation output signal.

8. The method of claim 7, wherein: in step S3, the nonlinear transformation is: y = [ xT, xH, (x.x.o.x) T, (x.x.x.o.t), (x.x.o.x) T, (x.x.x.o.x) T, (x.x.x.x.x) T ] T, where x is an input signal vector, y is a non-linear transformed sampled signal vector, (. eta.) T is a transposition operation, (. eta.) H is a conjugate transposition operation, (. eta. lambda. mark product.

9. The method of claim 7, wherein: in step S3, the nonlinear transformation is: y = [ x (1), x (3), …, x (P) ], x (P) = [ x1 x1 | P-1, …, xN-xN | P-1, x1 | x1 | P-1, …, x N | xN | P-1], wherein x = [ x1, …, xN ] is an input signal vector, y is a sampling signal vector after nonlinear transformation, | P is absolute value calculation, () P is P-th power calculation, P is an odd number, and P is not less than 3.

Technical Field

The invention relates to the technical field of satellite communication interference protection, in particular to a satellite communication ground station interference protection device and method.

Background

Satellite communication is a wireless communication technology that relies on satellite relays to achieve long-range information transmission. Satellite communication is one of the important means of military communication, is widely applied to mobile operation platforms such as ships and airplanes, and is commonly used for transmitting data such as tactical instructions, battlefield situations, audio and video calls and the like. Therefore, the success or failure of the satellite communication link is guaranteed safely and reliably. In actual combat, satellite communication needs to be capable of resisting electromagnetic interference released by enemies and ensuring smooth communication links. Therefore, it is an urgent technical problem to improve the interference protection capability of satellite communication.

The satellite communication ground station generally adopts high-gain antennas such as a parabolic antenna and a flat antenna to transmit and receive signals, and can suppress interference signals to a certain extent by utilizing the low side lobe characteristic of the antennas. However, in practice, the antenna side lobe gain can be reduced to a limited level, and therefore the interference suppression capability achieved by purely relying on the antenna side lobe is also limited. Especially when the direction of the interference source is close to the main lobe of the antenna, or when the interference source is positioned at the side lobe but the power is large, the requirement of actual interference resistance cannot be met by relying on the parabolic antenna alone.

To improve the interference suppression capability of the satellite access ground station, one method is to use an array antenna beam forming method. In brief, signals are received through a plurality of antenna units, and then vector synthesis is performed on the received signals, so that the null direction of the synthesized beam is aligned to an interference source, thereby realizing interference suppression.

Although there are a lot of reports in the literature on the beamforming interference suppression method, the following technical problems still need to be solved when applied to the satellite communication ground station:

first, it is difficult to be compatible with multiple communication standards: at present, satellite communication equipment does not adopt a unified standard, and multiple systems exist simultaneously, such as TDMA and FDMA systems, and therefore, communication satellites generally adopt a transparent forwarding mode to be compatible with different communication systems and protocols. Similarly, the interference prevention device must be transparent to the processing of the satellite communication received signals to ensure that the satellite communication received signals are applicable to various communication standards;

secondly, the device hardware and installation scheme are less versatile: the satellite earth station generally adopts a parabolic antenna, and cannot realize beam forming. Therefore, if the anti-interference technique of beam forming is used, additional antenna elements and circuits must be added. The added antenna unit and circuit need to be capable of being integrated with the existing satellite communication ground station equipment and being capable of adapting to a typical satellite communication ground station system structure;

thirdly, the access mode of the protection device is not flexible enough, i.e. the interference protection device needs to be difficult to conveniently access to the health ground station, and has the compatibility and universality requirements.

In order to improve the interference protection capability of a satellite ground station, the chinese patent "downlink interference suppression method for a dual-antenna satellite communication system" (application number: 201210551818.3) discloses a dual-antenna downlink interference suppression method, but the method needs to use a downlink training sequence for filter weight estimation, and therefore, cannot be applied to a communication system without a training sequence. Chinese patent "a method for canceling interference in satellite communication system" (application No. CN 107872268A) discloses a side lobe interference canceling method, but it cannot achieve multi-interference source suppression by using a single antenna unit, and does not disclose a specific circuit scheme. Chinese patent "non-cooperative interference suppression device and method for satellite ground station" (application No.: CN 107872268A) discloses a design scheme of an interference protection device for satellite ground station, but has the following disadvantages: (1) the adoption of a centralized auxiliary antenna is easy to be shielded by surrounding objects such as a satellite antenna and the like, and an airspace coverage blind area (2) exists and two independent modules are adopted to process beacon signals and data signals respectively, so that the circuit volume is large (3) and the traditional linear self-adaptive beam forming technology is adopted, the spatial resolution is limited, and the main lobe has poor anti-interference performance.

Disclosure of Invention

The present invention is directed to provide an interference protection device and method for a satellite communication ground station, which can be integrated with a satellite communication ground station device, can cover all directions, and has a smaller circuit size and a higher spatial resolution.

In order to achieve the purpose, the satellite communication ground station interference protection device comprises a sampling antenna array, wherein the sampling antenna array comprises N sampling antenna units, N is more than or equal to 1, and the device further comprises N +1 first-stage down-conversion modules, a feed clock module, N +1 second-stage down-conversion modules, N +1 analog-to-digital conversion modules, a digital signal processing module, a digital-to-analog conversion module, an up-conversion module and a first local vibration source module;

in the sampling antenna array, N sampling antenna units are respectively connected with the input ends of second to (N +1) th first-stage down-conversion modules, and the sampling antenna units collect interference signal samples from different spatial positions;

in the first-stage down-conversion module, the input end of the first-stage down-conversion module is connected with the output end of a parabolic satellite antenna, the input ends of other first-stage down-conversion modules are connected with the sampling antenna unit, the output end of the first-stage down-conversion module is respectively connected with a feed clock port of the feed clock module, and the first-stage down-conversion module filters, amplifies low noise and down-converts radio-frequency signals received by the satellite antenna and the sampling antenna unit into intermediate-frequency signals;

the output end of each intermediate frequency signal in the feed clock feed module is respectively connected with each input end of the second-stage down-conversion module, and the feed clock feed module outputs a plurality of paths of intermediate frequency signals output by the first-stage down-conversion module and provides power and reference clock signals for the first-stage down-conversion module;

each output end of the second-stage down-conversion module is respectively connected with each input end of the analog-to-digital conversion module, and the second-stage down-conversion module down-converts the intermediate frequency signals into baseband or lower intermediate frequency signals;

each output end of the analog-to-digital conversion module is connected with the input end of the digital signal processing module, and the analog-to-digital conversion module converts the received signals into digital signals and inputs the digital signals to the digital signal processing module;

the output end of the digital signal processing module is connected with the input end of the digital-to-analog conversion module, and the digital signal processing module realizes interference suppression processing in a digital domain and outputs a processed digital signal;

the output end of the digital-to-analog conversion module is connected with the input end of the upper frequency conversion module, and the digital-to-analog conversion module converts the digital signal output by the digital signal processing module into an analog baseband signal or an intermediate frequency signal;

the output end of the up-conversion module is connected with a satellite communication modem, and the up-conversion module up-converts the output signal of the digital-to-analog conversion module to the intermediate frequency signal frequency of a satellite communication ground station and outputs the intermediate frequency signal frequency;

the output of the first local vibration source module is connected with local vibration ports of the second-stage down-conversion module and the up-conversion module, and the first local vibration source module provides local vibration signals required by down-conversion and up-conversion, so that the signal frequency in the output is the same as the frequency of received intermediate frequency signals.

Preferably, the sampling antenna array is a distributed array antenna, each sampling antenna unit of the sampling antenna array is placed in a circular ring shape around the satellite antenna, a main beam of each sampling antenna unit points to a radial direction, an azimuth angle of the sampling antenna unit is 3dB, a beam width θ az is 3dB, a pitch angle of the sampling antenna unit is 3dB, the number of suppressible interference sources is K, and a satellite antenna side lobe maximum gain GS satisfies the following relationship: 2 pi ∙ M/N is not less than theta az is not less than 4 pi ∙ M/(10Gs/10 ∙ theta el), wherein M = ⌊ N ∙ theta az/(2 pi) ⌋, K is not less than M is not less than N, and ⌊ ∙ ⌋ is a rounding-down operation.

Preferably, the first stage down-conversion module comprises a preselection filter, a first low noise amplifier, a mixer, an intermediate frequency band-pass filter, a first duplexer, a first bias device and a second local oscillator module:

the input end of the preselection filter is connected with the sampling antenna unit or the guard antenna, and the output end of the preselection filter is connected with the input end of the first low-noise amplifier to filter signals outside a guard band;

the output end of the first low-noise amplifier is connected with the radio frequency input end of the frequency mixer, and low-noise amplification is carried out on a received signal;

the local oscillation input end of the frequency mixer is connected with the output end of the second local oscillation source module, and the output end of the frequency mixer is connected with the input end of the intermediate frequency band-pass filter, so that frequency mixing down-conversion processing is realized;

the output end of the intermediate frequency band-pass filter is connected with the intermediate frequency input end of the first duplexer and used for filtering image signals generated by frequency mixing;

a common port of the first duplexer is connected with the intermediate frequency and 10MHz reference composite radio frequency port of the first biaser, and a 10MHz output port is connected with a reference source port of the second local vibration source module to realize multiplexing of intermediate frequency and 10MHz reference signals;

the intermediate frequency, 10MHz and DC power supply composite port of the first biaser is connected with the feed clock port of the feed clock module, and the DC power port is connected with the power port of the second local oscillation source module and the power port of the first low-noise amplifier and is used for realizing multiplexing of an intermediate frequency signal, a 10MHz reference signal and a DC power supply to a same interface;

the output end of the second local vibration source module is connected with the local vibration signal input end of the frequency mixer and used for generating local vibration signals required by frequency mixing, and the second local vibration source modules have the same frequency and share the same reference clock source.

Preferably, the sampling antenna array and the first stage down-conversion module are integrated and mounted on a base inside a radome of the health and earth station.

Preferably, the feeding clock module includes N +1 second biasers, N +1 second duplexers, a power module, a multi-path power divider, a second low noise amplifier, and a crystal oscillator, where:

the second biasers respectively comprise a second biaser common terminal, a second biaser radio-frequency terminal and a second biaser direct-current terminal, the second biaser common terminal is connected with the intermediate-frequency terminal of the first-stage down-conversion module, the second biaser direct-current terminal is connected with the output terminal of the power supply module, and the second biaser radio-frequency terminal is connected with a second duplexer common terminal of the second duplexer;

the second duplexers respectively comprise a second duplexer common end, a second duplexer high-frequency end and a second duplexer low-frequency end, the second duplexer high-frequency end is connected with each input end of the second-stage down-conversion module, the second duplexer low-frequency end is connected with each output end of the multi-path power divider, and the intermediate frequency signal and the reference clock signal are transmitted in two directions at the same end;

the input end of the power supply module is connected with an external power supply, and the output end of the power supply module is respectively connected with the direct current end of each second biaser and the power supply end of the crystal oscillator to supply power to the first-stage down-conversion module and the crystal oscillator;

the input end of the multi-path power divider is connected with the output end of the second low-noise amplifier, and the output end of the multi-path power divider is respectively connected with the low-frequency end of each second duplexer and used for dividing the signal generated by the crystal oscillator into N +1 paths of equal power;

the input end of the second low-noise amplifier is connected with the output end of the crystal oscillator, the output end of the second low-noise amplifier is connected with the input end of the multi-path power divider, and signals generated by the crystal oscillator are subjected to low-noise amplification;

and the output end of the crystal oscillator is connected with the input end of the second low-noise amplifier to generate a clock signal which is required to be referred by the first-stage down-conversion module.

Preferably, the ports of the first stage down-conversion module and the feeding clock feeding module are connected by cables, and the feeding clock feeding module and the second stage down-conversion module are connected by cables.

A satellite communication ground station interference protection method comprises the following steps:

s1: installing the satellite communication ground station interference protection device;

s2: inputting the satellite antenna receiving signal and the sampling antenna unit receiving signal into a band-pass filter, and filtering out the out-of-band interference signal and noise of the communication signal;

s3: inputting the filtered received signal of the sampling antenna unit into a nonlinear space-time beam former to realize nonlinear transformation and obtain a sampling signal after the nonlinear transformation;

s4: carrying out linear weighted synthesis on the sampling signals after nonlinear transformation to obtain interference cancellation signals;

s5: synthesizing the interference cancellation signal and the filtered satellite communication antenna receiving signal to realize interference suppression;

s6: and adopting a self-adaptive filtering algorithm to iteratively adjust the weighted weight of the sampling signal so as to minimize the average power of the cancellation output signal.

Preferably, in step S3, the nonlinear transformation is: y = [ xT, xH, (x.x.o.x) T, (x.x.x.o.t), (x.x.o.x) T, (x.x.x.o.x) T, (x.x.x.x.x) T ] T, where x is an input signal vector, y is a non-linear transformed sampled signal vector, (. eta.) T is a transposition operation, (. eta.) H is a conjugate transposition operation, (. eta. lambda. mark product.

Preferably, in step S3, the nonlinear transformation is: y = [ x (1), x (3), …, x (P) ], x (P) = [ x1 x1 | P-1, …, xN-xN | P-1, x1 | x1 | P-1, …, x N | xN | P-1], wherein x = [ x1, …, xN ] is an input signal vector, y is a sampling signal vector after nonlinear transformation, | P is absolute value calculation, () P is P-th power calculation, P is an odd number, and P is not less than 3.

Compared with the prior art, the invention has the following advantages:

1. the method is applicable to various communication systems: the invention realizes the transparent processing and transmission of communication signals through digital storage and forwarding, is suitable for various communication systems, processes at a signal level, does not depend on the communication system and a protocol, processes satellite communication intermediate frequency signals, and does not obviously reduce the signal-to-noise ratio of received signals in the process of digital storage and forwarding, thereby ensuring the performance of a communication link while realizing interference protection;

2. the device circuit structure can be adapted to a typical satellite communication device: the device adopts independent sampling antennas, a first-stage down-conversion module, a feed clock, a second-stage down-conversion module, a digital-to-analog conversion module, a digital signal processing module, an up-conversion module, a first local vibration source module and other hardware modules, does not depend on a guard device, and guarantees the universality of the device;

3. the interface is simple, the access mode is flexible: the interface between the interference protection device and the satellite communication equipment only comprises an intermediate frequency input port and an intermediate frequency output port, the interface is simple, a satellite communication ground station firstly down-converts a satellite communication antenna receiving signal to an intermediate frequency and then transmits the intermediate frequency signal to a modem in a long distance, and the interface is provided with an open intermediate frequency interface, so that the interference protection device is very flexible to access in an intermediate frequency link;

4. the design of the sampling antenna array can realize all-round coverage, and the installation is flexible: the distributed sampling antenna array structure is adopted, each antenna unit and each first-stage down-conversion module are independent and can be flexibly distributed, the sampling antenna is placed around the satellite antenna, so that the shielding of the satellite antenna on the sampling antenna is avoided, the covering capability of the satellite antenna on the direction of an interference source is improved, the sampling antenna unit and the first-stage down-conversion module are integrated into a whole, the size of the module can be reduced, and the distributed sampling antenna array structure is convenient to install in a satellite antenna cover;

5. the circuit structure is simple: the invention adopts a single digital signal processing circuit to simultaneously process the beacon signal and a plurality of data signals, thereby greatly reducing the circuit size;

6. better interference protection performance: the invention adopts a nonlinear beam forming algorithm, simultaneously utilizes conjugate transformation components and high-order nonlinear transformation components of sampling signals, and can realize higher spatial resolution capability for non-Gaussian interference signals and especially improve the main lobe anti-interference performance compared with a method of only using narrow linear components in the traditional linear beam forming algorithm.

Drawings

FIG. 1 is a schematic structural diagram of an interference prevention device for a satellite communication ground station according to the present invention;

FIG. 2 is a schematic diagram of a first stage down-conversion module in FIG. 1;

FIG. 3 is a schematic structural diagram of the feeding clock module in FIG. 1;

FIG. 4 is a schematic diagram of the method for interference protection of a satellite communication ground station according to the present invention;

FIG. 5 is a schematic diagram illustrating an exemplary embodiment of an antenna unit;

FIG. 6 is an example of interference suppression effect of the embodiment;

fig. 7 is a graph comparing the performance of the non-linear beamforming anti-interference algorithm of the present embodiment with that of the conventional linear beamforming algorithm.

The components in the figures are numbered as follows:

the antenna system comprises a sampling antenna unit 1, a first-stage down-conversion module 2, a feeding clock module 3, a second-stage down-conversion module 4, an analog-to-digital conversion module 5, a digital signal processing module 6, a digital-to-analog conversion module 7, an up-conversion module 8, a first local oscillator source module 9, a guard antenna 10, a satellite communication modem 11, a preselection filter 21, a first low-noise amplifier 22, a mixer 23, an intermediate frequency band-pass filter 24, a first duplexer 25, a first biaser 26, a second local oscillator source module 27, a power supply module 31, a multi-path power divider 32, a crystal oscillator 33, an external power supply 34, a second biaser 35, a second duplexer 36, a second low-noise amplifier 37, a second biaser common terminal 351, a second biaser radio frequency terminal 352, a second biaser direct current terminal 353, a second duplexer common terminal 361, a second duplexer high-frequency terminal 362 and a second duplexer low-frequency terminal 363.

Detailed Description

The invention is described in further detail below with reference to the figures and the specific embodiments.

As shown in fig. 1, the interference protection device for a satellite communication ground station of the present invention includes a sampling antenna array, where the sampling antenna array includes N sampling antenna units 1, N is greater than or equal to 1, and further includes N +1 first-stage down-conversion modules 2, a feed clock module 3, N +1 second-stage down-conversion modules 4, N +1 analog-to-digital conversion modules 5, a digital signal processing module 6, a digital-to-analog conversion module 7, an up-conversion module 8, and a first local oscillation source module 9;

in the sampling antenna array, N sampling antenna units 1 are respectively connected with the input ends of second to (N +1) th first-stage down-conversion modules 2, and the sampling antenna units 1 collect interference signal samples from different spatial positions;

in the first-stage down-conversion module 2, the input end of the first-stage down-conversion module 2 is connected with the output end of the parabolic satellite antenna 10, the input ends of other first-stage down-conversion modules 2 are connected with the sampling antenna unit 1, the output end of the first-stage down-conversion module 2 is respectively connected with the feed clock port of the feed clock feed module 3, and the first-stage down-conversion module 2 filters and amplifies low-noise radio-frequency signals received by the satellite antenna 10 and the sampling antenna unit 1 and down-converts the radio-frequency signals into intermediate-frequency signals;

the output end of each intermediate frequency signal in the feed clock module 3 is respectively connected with each input end of the second-stage down-conversion module 4, and the feed clock feed module 3 outputs the multi-path intermediate frequency signals output by the first-stage down-conversion module 2 and provides power and reference clock signals for the first-stage down-conversion module 2;

each output end of the second-stage down-conversion module 4 is respectively connected with each input end of the analog-to-digital conversion module 5, and the second-stage down-conversion module 4 down-converts the intermediate frequency signal into a baseband or lower intermediate frequency signal;

each output end of the analog-to-digital conversion module 5 is connected with the input end of the digital signal processing module 6, and the analog-to-digital conversion module 5 converts the received signals into digital signals and inputs the digital signals to the digital signal processing module 6;

the output end of the digital signal processing module 6 is connected with the input end of the digital-to-analog conversion module 7, and the digital signal processing module 6 realizes interference suppression processing in a digital domain and outputs the processed digital signal;

the output end of the digital-to-analog conversion module 7 is connected with the input end of the upper frequency conversion module 8, and the digital-to-analog conversion module 7 converts the digital signal output by the digital signal processing module 6 into an analog baseband signal or an intermediate frequency signal;

the output end of the up-conversion module 8 is connected with a satellite communication modem 11, and the up-conversion module 8 up-converts the output signal of the digital-to-analog conversion module 7 to the intermediate frequency signal frequency of the satellite communication ground station and outputs the intermediate frequency signal frequency;

the output of the first local vibration source module 9 is connected to local vibration ports of the second-stage down-conversion module 4 and the up-conversion module 8, and the first local vibration source module 9 provides local vibration signals required by down-conversion and up-conversion, so that the signal frequency in the output is the same as the frequency of the received intermediate frequency signal.

The sampling antenna array is a distributed array antenna, each sampling antenna unit 1 of the sampling antenna array is annularly arranged around the satellite antenna 10, the main beam of each sampling antenna unit 1 points to the radial direction, the azimuth angle 3dB beam width theta az and the pitch angle 3dB beam width theta el of the sampling antenna unit are arranged, the number of suppressible interference sources is K, and the satellite antenna side lobe maximum gain GS meets the following relation: 2 pi ∙ M/N is not less than theta az is not less than 4 pi ∙ M/(10Gs/10 ∙ theta el), wherein M = ⌊ N ∙ theta az/(2 pi) ⌋, K is not less than M is not less than N, and ⌊ ∙ ⌋ is a rounding-down operation.

In this embodiment, as shown in fig. 5, a 4-unit distributed array antenna is adopted and placed around the satellite communication antenna 10 at equal intervals; the azimuth angle 3dB beam width of the sampling antenna unit 1 is 90 degrees, the pitch angle 3dB beam width is 20 degrees, and the sampling antenna unit 1 points to the radial direction. The angular range of the interference source which can be covered by the sampling antenna array is 0-360 degrees of azimuth angle and +/-10 degrees of pitch angle; 1-4 interference sources can be suppressed, and the maximum array gain is 10 dB.

In this embodiment, as shown in fig. 2, the first stage down-conversion module 2 includes a preselection filter 21, a first low-noise amplifier 22, a mixer 23, an intermediate frequency band-pass filter 24, a first duplexer 25, a first bias 26, and a second local oscillator module 27:

the input end of the preselection filter 21 is connected with the sampling antenna unit 1 or the satellite antenna 10, and the output end is connected with the input end of the first low-noise amplifier 22 to filter signals outside a satellite frequency band;

the output end of the first low-noise amplifier 22 is connected with the radio-frequency input end of the mixer 23, and low-noise amplification is carried out on the received signal;

the local oscillation input end of the frequency mixer 23 is connected with the output end of the second local oscillation source module 27, and the output end is connected with the input end of the intermediate frequency band-pass filter 24, so that frequency mixing down-conversion processing is realized;

the output end of the intermediate frequency band-pass filter 24 is connected with the intermediate frequency input end of the first duplexer 25 and used for filtering an image signal generated by frequency mixing;

a common port of the first duplexer 25 is connected to the intermediate frequency and 10MHz reference composite radio frequency port of the first biaser 26, and a 10MHz output port is connected to a reference source port of the second local oscillator module 27, so as to realize multiplexing of intermediate frequency and 10MHz reference signals;

the intermediate frequency, 10MHz and dc power supply composite port of the first biaser 26 is connected to the feeding clock port of the feeding clock module 3, and the dc power supply port is connected to the power supply port of the second local oscillation source module 27 and the power supply port of the first low-noise amplifier 22, so as to realize that the intermediate frequency signal, the 10MHz reference signal and the dc power supply multiplex the same interface;

the output end of the second local oscillation source module 27 is connected to the local oscillation signal input end of the frequency mixer 23, and is configured to generate a local oscillation signal required for frequency mixing, and the second local oscillation source modules 27 have the same frequency and share the same reference clock source.

In the embodiment, the passband of the preselection filter 21 is 12.25-12.75 GHz, which is the same as the satellite communication receiving frequency band; the noise coefficient of the first low-noise amplifier 22 is 1dB, and the gain is 30 dB; the local oscillation frequency generated by the second local oscillation source module 27 is 11.3GHz, and the corresponding intermediate frequency signal is 0.95-1.45 GHz.

As shown in fig. 3, the feeding clock module 3 includes N +1 second biasers 35, N +1 second duplexers 36, a power module 31, a demultiplexer 32, a second low-noise amplifier 37, and a crystal oscillator 33, where:

the second biasers 35 each comprise a second biaser common terminal 351, a second biaser rf terminal 352 and a second biaser dc terminal 353, the second biaser common terminal 351 is connected to the if terminal of the first stage down conversion module 2, the second biaser dc terminal 353 is connected to the output terminal of the power module 31, and the second biaser rf terminal 352 is connected to a second duplexer common terminal 361 of the second duplexer 36;

the second duplexers 36 each include a second duplexer common terminal 361, a second duplexer high frequency terminal 362 and a second duplexer low frequency terminal 363, the second duplexer high frequency terminal 362 is connected to the respective input terminals of the second stage down-conversion module 2, the second duplexer low frequency terminal 363 is connected to the respective output terminals of the multiplexer 32, and the intermediate frequency signal and the reference clock signal are transmitted in two directions at the same terminal;

the input end of the power module 31 is connected to an external power source 34, and the output end is respectively connected to the dc end 353 of each second biaser and the power end of the crystal oscillator 33, so as to supply power to the first stage down conversion module 2 and the crystal oscillator 33;

the input end of the multi-path power divider 32 is connected to the output end of the second low-noise amplifier 37, and the output end of the multi-path power divider is connected to the low-frequency end 363 of each second duplexer respectively, so as to divide the signal generated by the crystal oscillator 33 into N +1 paths;

the input end of the second low-noise amplifier 37 is connected with the output end of the crystal oscillator 33, the output end of the second low-noise amplifier is connected with the input end of the multi-path power divider 32, and signals generated by the crystal oscillator 33 are subjected to low-noise amplification;

the output end of the crystal oscillator 33 is connected to the input end of the second low-noise amplifier 37 to generate a clock signal to be referred by the first stage down-conversion module 2, in this embodiment, the crystal oscillator 33 generates a 10MHz sine wave reference signal to ensure that the local oscillation frequencies of the first stage down-conversion modules 2 are consistent, and ensure that the frequencies of the output intermediate frequency signals are consistent, which is a necessary condition for realizing array beam forming.

In addition, in this embodiment, the sampling antenna array and the first-stage down-conversion module 2 are integrated and installed on the base inside the antenna housing of the sanitary and public ground station. The ports of the first-stage down-conversion module 2 and the feed clock module 3 are connected by cables, and the feed clock module 3 and the second-stage down-conversion module 4 are connected by cables, so that long-distance intermediate-frequency signal transmission is realized. Since the satellite communication modem 11 is generally placed in a cabin and the satellite communication antenna 10 is placed outside the cabin and has a length of several tens of meters, other modules such as the feed clock module 3 can be placed indoors and near the satellite communication modem 11.

Referring to fig. 4, the method for protecting an interference protection device of a satellite communication ground station in this embodiment includes the following steps:

s1: installing the satellite communication ground station interference prevention device of claim 1;

s2: inputting satellite antenna receiving signals x0(n) and sampling antenna unit receiving signals x1(n), …, xn (n) into band-pass filters hbpf (n) to filter out communication signal out-of-band interference signals and noise, and respectively obtaining filtered satellite antenna receiving signals d (n) = x0(n) ∗ hbpf (T) and filtered sampling antenna unit receiving signals v (n) = [ v1(n), …, vn (n) T, wherein vn (n) = xn (n) ∗ hbpf (n) is convolution operation, and the step is used for filtering out communication signal out-of-band interference and noise signals;

s3: inputting the filtered received signal of the sampling antenna unit into a nonlinear space-time beam former to realize nonlinear transformation and obtain a sampling signal after the nonlinear transformation:

u(n)=[uTlinear(n), uTnonlinear(n)]T

wherein the content of the first and second substances,

ulinear(n)=[vT(n),vH(n)]T

unonlinear(n)= [(v(n)○•v(n)○•v(n))T,(v(n)○•v(n)○•v(n)*)T,(v(n)○•v(n)*○•v(n)*)T, (v(n)*○•v(n)*○•v(n)*)T]T

wherein (·) T is a transpose operation, (. H) is a conjugate transpose operation, (. eta.) is a conjugate operation,. o.is a Hadamard product;

s4: carrying out linear weighted synthesis on the sampling signals after nonlinear transformation to obtain interference cancellation signals y (n) = wH (n) u (n), wherein w (n) is the weight of a nonlinear beam former;

s5: synthesizing the interference cancellation signal and the filtered satellite communication antenna receiving signal to realize interference suppression, wherein the specific process is as follows: cancelling the output signal e (n) = d (n) -y (n);

s6: adopting adaptive filtering algorithm to iteratively adjust the weighted weight of the sampling signal to minimize the average power E (| E (n)2 |) of the cancellation output signal, which comprises the following steps: w (n +1) = w (n) + μ e × n) u (n), where μ is the step size.

In other embodiments, the non-linear transformation of step S3 may also be:

y = [ x (1), x (3), …, x (P) ], x (P) = [ x1 | x1 | P-1, …, xN | P-1, [ 1 | x1 | P-1, …, x | N | xN | P-1], wherein x = [ x1, …, xN ] is an input signal vector, y is a sampling signal vector after nonlinear transformation, (. quadrature) is an absolute value operation, P is a P-th power operation, P is an odd number, and P is not less than 3.

Fig. 6 shows an example of the interference rejection effect in this embodiment. Wherein the azimuth angle of the interference signal is 30 degrees, and the pitch angle is 0 degree. The frequency spectrums of interference signals before and after interference resistance are shown in the figure, wherein the solid line is the frequency spectrum of the received signal when the interference protection device is closed, and the dotted line is the frequency spectrum of the received signal when the interference protection device is opened. Therefore, interference signals are effectively suppressed, and communication signals are recovered, so that the satellite communication link is guaranteed to be normal.

As shown in fig. 7, the output signal to interference plus noise ratios obtained by the interference source under different angle conditions by using the conventional linear beam forming and the nonlinear beam forming interference rejection algorithm in the embodiment of the present invention are shown. The azimuth angle of the interference source is the same as the azimuth angle of the satellite, and the included angle between the pitch angle and the main beam direction of the satellite antenna is 0-5 degrees. As can be seen from the figure, the method provided by the invention can obviously improve the anti-interference performance. Especially, when the interference source is close to the main lobe of the satellite communication antenna, the high output signal-to-interference-and-noise ratio is achieved.