CN115865115A - System and method for suppressing mirror image interference in zero intermediate frequency architecture software radio - Google Patents

Abstract

The invention discloses a system and method for suppressing image interference in a software radio with a zero-IF architecture, including an array receiving antenna, a receiving parameter setting module, a radio frequency channel, a signal processing module, and a software receiver. The signals received by the array receiving antenna are sequentially received by receiving Parameter setting module, radio frequency channel, signal processing module and software receiver. The present invention only slightly modifies the software on the existing software and hardware resources, without changing the original zero-IF hardware structure, utilizes the characteristics of the received signal, sets corresponding parameters, and realizes image interference and useful signals while taking advantage of the advantages of the zero-IF structure separation. The suppression of image interference is realized through subsequent cascaded complex bandpass filters, thereby eliminating the image interference problem caused by IQ imbalance.

Description

System and method for image interference suppression in software radio with zero-IF architecture

technical field

The invention relates to the technical field of array signal processing, in particular to a system and method for suppressing image interference in a software radio with a zero-IF architecture.

Background technique

With the development and upgrading of radio technology, software radio with zero-IF architecture provides an open, standardized, and modular general-purpose programmable hardware platform, which can meet the working requirements of various communication protocols, operating frequency bands, and modulation methods. At present, major manufacturers are researching on the amount of investment in software and hardware integration technology. Among them, the AD936x or AD937x series channel integrated RF front-end circuits launched by Analog Devices are widely used in the field of wireless communication due to their high performance and high integration, covering 300MHz~ 6GHz frequency range. In the AD936x or AD937x series dual-channel RF transceivers, the functions of filtering, amplification, quadrature mixing, and analog-to-digital conversion are integrated, and the mixing uses quadrature dual-channel processing technology to realize down-conversion. This design brings two Advantages, on the one hand, the available bandwidth of the system can be increased while the sampling frequency remains unchanged; on the other hand, the IQ complex signal can provide clear instantaneous amplitude and phase information, which is widely used in the modern communication field and the design of navigation receivers.

In the prior art, based on the AD936x or AD937x series radio frequency board and FPGA as the core baseband board, the zero-IF architecture software radio general platform can be applied to the design of anti-jamming navigation receiver, although it adopts quadrature mixing to provide High bandwidth and accurate signal information, but in reality, it is impossible to achieve the complete orthogonality of the I\Q two-way mixing output, resulting in the decline of the anti-jamming ability of the receiver in the actual interference environment, resulting in a decrease in navigation accuracy and even a loss of reception The machine is completely unlocked.

Contents of the invention

The object of the present invention is to provide a system and method for suppressing image interference in a software radio with a zero-IF architecture, so as to solve the IQ quadrature mismatch that exists in the front-end of the radio frequency of a software radio definition receiver with a zero-IF architecture, and then lead to a GNSS antenna based on this hardware structure The problem of anti-jamming performance degradation of the array receiver.

In order to achieve the above object, the present invention provides the following technical solutions: comprising an array receiving antenna, a receiving parameter setting module, a radio frequency channel, a signal processing module and a software receiver, the signals received by the array receiving antenna pass through the receiving parameter setting module, the radio frequency channel in sequence , signal processing module and software receiver.

Preferably, the array receiving antenna is a multi-element receiving antenna, and the arrangement of the multi-element receiving antenna includes a uniform linear array, a square array and a circular array.

Preferably, the radio frequency channel includes a filtering module, an amplifying module, a quadrature mixing module, a low-pass filtering module and an analog-to-digital conversion module.

Preferably, the signal processing module includes a sampling module, a digital domain filter processing module and a data storage module, and the digital domain filter processing module includes a complex bandpass filter.

Preferably, the real part and the imaginary part of the complex bandpass filter coefficients are obtained by transforming the real number bandpass filter to obtain an analytical function.

Preferably, the software receiver includes an anti-interference processing module, a capturing module and a tracking module.

A method for suppressing image interference in software radio with zero intermediate frequency architecture, comprising the following steps:

S1: The array receiving antenna receives satellite signals and interference from space, and each array element transmits the received signal to the general software radio platform based on the radio frequency channel;

其中f_s为有用信号中心频率，B_s为有用信号带宽；S2: According to the bandwidth B _s of the required satellite signal and the characteristics of the center frequency f _s signal system, optimize the setting of the local oscillator frequency f _lo and the sampling rate F _s at the receiving end, that is, the original local oscillator frequency is equal to the center frequency of the received signal, and configure for the local oscillator frequency to satisfy the

Where f _s is the center frequency of the useful signal, and B _s is the bandwidth of the useful signal;

The sampling rate F _s satisfies: F _s > 2f _h , where f _h is the maximum frequency point of the main peak bandwidth of the received signal;

Satisfying the above conditions can obtain the optimal parameter configuration of the local oscillator frequency and sampling rate under different received signals;

S3: The signal received by the array receiving antenna is down-converted and analog-to-digital converted through the radio frequency channel to obtain a digital domain signal, and the stripping of the image signal is realized;

S4: After the signal reaches the signal processing module, the received data of the I channel and the Q channel are processed by a complex bandpass filter. There is only one passband, that is, the signal that can only pass through the positive frequency band or the negative frequency band. For the analysis signal, after filtering After processing, the spectrum of the refined frequency bands f1-f2 is reserved, and the corresponding negative frequency domain part is suppressed, thereby eliminating the influence of image interference on the anti-jamming ability of the navigation receiver terminal.

Compared with prior art, the beneficial effect of the present invention is:

1. The present invention only slightly modifies the software on the existing hardware and software resources without changing the original zero-IF hardware structure, utilizes the characteristics of the received signal, and realizes image interference and Separation of useful signals. The suppression of image interference is realized through subsequent cascaded complex band-pass filters, thereby eliminating the image interference problem caused by IQ imbalance.

Description of drawings

Figure 1 is a structural block diagram of image interference processing based on the zero-IF architecture software radio general platform IQ mismatch;

Figure 2 is a schematic diagram of the spectrum before the IQ mismatch processing of the received signal of the general software radio platform based on the AD936x or AD937x series;

Figure 3 is a schematic diagram of the frequency spectrum after the IQ mismatch processing of the received signal of the general software radio platform based on the AD936x or AD937x series;

Fig. 4 is a flow chart of complex number bandpass digital filter design;

Fig. 5 is the concrete implementation scheme of the complex number bandpass filter of digital processing part;

Figure 6 is an implementation effect diagram of the number of trackable satellites after the receiver captures and tracks before and after IQ imbalance improvement under different broadband interference intensities;

Figure 7 is an implementation effect diagram of the PRN20 satellite output carrier-to-noise ratio after receiver capture and tracking before and after IQ imbalance improvement under different broadband interference intensities;

Figure 8 is a comparison result of the number of satellites captured by the receiver before and after improvement.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In the existing technology, the current software radio general platform receiver based on AD936x and AD937x series RF boards generally adopts the zero-IF architecture design scheme introduced by ADI, which can improve the integration level and reduce the impact of nonlinearity on the system in the RF board design. Influence, AD936x and AD937x series RF boards provide up to 20MHz ~ 100MHz channel bandwidth, AD936x or AD937x series of wideband RF transceivers launched by ADI are obtained in the general platform of zero-IF architecture software radio by virtue of high integration, low noise figure and versatility In order to be widely used, the main function of the AD936x or AD937x series RF board at the receiving end is to complete amplification, filtering, quadrature mixing, automatic gain control, and analog-to-digital conversion. The complex signal obtained by quadrature mixing can save half of the frequency band resources, but in the analog channel, due to the influence of manufacturing tolerances and ambient temperature, the AD936x or AD937x series RF boards cannot complete the I/Q quadrature down-conversion process. Avoid the amplitude and phase mismatch of the in-phase and quadrature signals, so that the zero-IF architecture software radio definition receiver based on the RF board and FPGA baseband board has IQ quadrature mismatch at the RF front end, resulting in image interference, and then As a result, the anti-jamming performance of the GNSS antenna array receiver based on this hardware structure is reduced,

Among them, the parameter setting method of the original zero-IF architecture receiver: by setting the local oscillator frequency f _lo as the center frequency f _s of the received signal, that is, f _lo = f _s ; directly down-convert the useful signal to the baseband, and the specific conversion process includes satellite signals, The interference signal is transmitted from the receiving antenna to the RF board to complete filtering, quadrature down-conversion, and analog-to-digital conversion to obtain a complex baseband signal composed of I and Q channels. And eliminate invalid out-of-band signals through the digital low-pass filter designed by the FPGA module. However, the zero-IF architecture software radio universal receiver platform based on this scheme inevitably keeps the image interference caused by IQ imbalance in the main frequency band of the useful signal, which brings troubles to interference suppression.

Please refer to Fig. 1-8, the present invention provides a kind of technical solution: including array receiving antenna, receiving parameter setting module, radio frequency channel, signal processing module and software receiver, the signal received by array receiving antenna passes through receiving parameter setting module, radio frequency channels, signal processing modules, and software receivers.

The array receiving antenna is a multi-element receiving antenna, and the arrangement of the multi-element receiving antenna includes a uniform linear array, a square array and a circular array.

The radio frequency channel includes a filter module, an amplification module, a quadrature mixing module, a low-pass filter module and an analog-to-digital conversion module. The radio frequency channel is widely used in navigation receivers, and AD936x or AD937x series radio frequency boards are used to complete amplification, Number conversion and other functions. In the following analysis, the highly integrated dual-channel wideband transceiver AD9371 is used as the radio frequency board for illustration. Because of its wide frequency and large bandwidth design, this series of devices provides a communication system for different operating frequencies, modulation methods and coding techniques. Generic software radio common platform with satellite communication.

The signal processing module includes an FPGA processing chip.

The RF transceiver based on AD9371 integrates two RF transceiver channels, each RF channel contains an adjustable analog transconductance low-pass filter, quadrature down-conversion, automatic gain control, and analog-to-digital converter, which are processed by the FPGA baseband board The module completes signal processing functions such as digital filtering and digital demodulation, and the receiving link also includes auxiliary functions such as quadrature error correction, DC bias, and digital gain compensation.

In the traditional mode, the software radio hardware platform based on AD9371 zero-IF architecture adopts the quadrature down-conversion mode to convert the signal from radio frequency to baseband signal. The advantage brought by quadrature mixing is to save half of the spectrum resources while providing more signal information. However, due to the influence of manufacturing tolerances in the actual system, it is difficult for the I and Q branches to achieve consistent amplitudes and orthogonal phases, resulting in image interference.

Although ADI has integrated quadrature auxiliary correction in the digital domain in the RF board to solve this problem, and the image rejection ratio given in the manual is as high as 75dB, but it cannot actually achieve such a high rejection effect.

Figure 2 is a schematic diagram of the signal spectrum received by the AD9371-based general software radio platform before performing IQ quadrature mismatch suppression. After filtering and quantization, x(n) is obtained. From the spectrum diagram, it can be seen that the interference and its image interference are located in the useful within the signal band.

In the design based on this general platform, according to the characteristics of the signal system of the data signal s(t) received by the GNSS antenna array, the center frequency and sampling rate adjustment of signal reception are realized through software programming. The current design for this general platform is to directly down-convert the received signal to the baseband, but it will inevitably bring about IQ imbalance, which will have a great impact on the quality of the GNSS signal at the receiving end. Especially for navigation receivers with limited degrees of freedom in anti-jamming, the degree of freedom required for anti-jamming cannot be met, resulting in the receiver not working properly.

The signal processing module includes a sampling module, a digital domain filter processing module and a data storage module, and the digital domain filter processing module includes a complex bandpass filter.

The real and imaginary parts of the coefficients of the complex bandpass filter are obtained by transforming the real bandpass filter into an analytic function.

The complex bandpass filter is obtained in the following way:

First design a real bandpass filter that meets the needs of the actual system, and obtain the N-order coefficient h(n) of the real bandpass filter; perform a Hilbert transform on the real bandpass filter to obtain an analytical function, thereby obtaining a complex bandpass The real and imaginary parts of the filter coefficients are denoted as coe_I and coe_Q, respectively.

The software receiver includes anti-interference processing module, capture module and tracking module.

A method for suppressing image interference in software radio with zero intermediate frequency architecture, comprising the following steps:

S1: The array receiving antenna receives satellite signals and interference from space, and each array element transmits the received signal to the general software radio platform based on the radio frequency channel;

其中f_s为有用信号中心频率，B_s为有用信号带宽；S2: According to the bandwidth B _s of the required satellite signal and the characteristics of the center frequency f _s signal system, optimize the setting of the local oscillator frequency f _lo and the sampling rate F _s at the receiving end, that is, the original local oscillator frequency is equal to the center frequency of the received signal, and configure for the local oscillator frequency to satisfy the

Where f _s is the center frequency of the useful signal, and B _s is the bandwidth of the useful signal;

According to the Nyquist sampling theorem, set the sampling rate F _s at the receiving end to satisfy: F _s > 2f _h , where f _h is the maximum frequency point of the main peak bandwidth of the received signal;

Taking the GPS L1 band receiving signal as an example, the center frequency is 1575.42MHz, and its main lobe bandwidth is 2.046MHz. The local oscillation frequency of the navigation receiver of the zero-IF architecture software radio general platform is set to 1571.42MHz; the sampling rate is 20MHz;

Satisfying the above conditions can obtain the optimal parameter configuration of the local oscillator frequency and sampling rate under different received signals;

S3: The signal received by the array receiving antenna is down-converted and analog-to-digital converted by the AD9371 integrated transceiver module in the radio frequency channel to obtain a digital domain signal. The corresponding signal spectrum is shown in Figure 3. It can be seen that this Optimize the setting of vibration frequency and sampling rate parameters, which can realize the stripping of image signals;

的频谱特点，只有一个通带即只能通过正频带或者负频带的信号。对于解析信号，经过滤波处理后，细化频带f1～f2的频谱被保留，而对应的负频域部分被抑制，从而消除镜像干扰对导航接收机终端抗干扰能力的影响。S4: After the signal reaches the signal processing module, use the FPGA to process the received I-channel and Q-channel data with a complex band-pass filter. The specific complex band-pass digital filter design scheme is shown in Figure 4. The conventional real-number band-pass The filter coefficients are designed according to the characteristics of the received signal to design the coefficients required for digital filter design in the FPGA, that is, the unit impulse response h(n). For the real number bandpass filter, it has two passbands, including the positive frequency domain part and the negative frequency domain part, and has symmetry, so the conventional filter cannot suppress the image interference, according to the analytical function

Spectrum characteristics, there is only one passband, that is, signals that can only pass through positive or negative frequency bands. For the analytic signal, after filtering, the spectrum of the refined frequency band f1-f2 is reserved, and the corresponding negative frequency domain part is suppressed, thereby eliminating the influence of image interference on the anti-jamming capability of the navigation receiver terminal.

的频谱特点，/>

可将对应负频率的镜像干扰滤除。Further, after the parameter optimization configuration is completed, the signal is received by the array receiving antenna, and the signal in the digital domain is obtained after filtering, amplification, quadrature mixing and analog-to-digital conversion in the radio frequency channel. Through the aforementioned parameter configuration, the image interference generated by the IQ imbalance can be moved to the negative frequency part away from the frequency band of the useful signal, so as to realize the separation of the image interference and the frequency band of the useful signal. After the image interference stripping is realized above, the image interference needs to be suppressed. After the quadrature signal generated at the radio frequency end reaches the digital signal processing module, the received digital domain data of the I channel and the Q channel are processed through a complex bandpass filter by the FPGA. The conventional method of generating a real bandpass filter is to set the type, order, passband stopband frequency, passband stopband ripple, and sampling rate of the real number bandpass filter according to the actual system index to obtain the bandpass filter. The N-order coefficients of the device generate the unit impulse response h(n). For the real number filter, it has two passbands, including the positive frequency domain part and the negative frequency domain part, and has symmetry. It can be seen that the conventional filter cannot suppress image interference. However, using the spectral characteristics of h(n) corresponding to the analytical function can achieve the effect of retaining positive frequencies and suppressing negative frequencies. In order to suppress the image interference in the negative frequency domain, it is necessary to use the analytical function

The spectral characteristics of the, />

Image interference corresponding to negative frequencies can be filtered out.

和

得到镜像干扰抑制后的信号y_out，其实部数据和虚部数据分别为real(y_out)和image(y_out)。对应的，经过镜像干扰抑制的数据由如下方式得到其对应实部和虚部：In the actual hardware design, it is not possible to directly operate on complex numbers. In order to implement image suppression through complex bandpass filter design for complex signals composed of I-channel signals and Q-channel signals, the following operations are performed. Assuming that the IQ channel data are data_I and data_Q respectively, the real part and imaginary part coefficients of the corresponding complex bandpass filter are respectively

and

The signal y_out after image interference suppression is obtained, and the real part data and imaginary part data are real(y_out) and image(y_out) respectively. Correspondingly, the corresponding real and imaginary parts of the data that have been suppressed by image interference are obtained as follows:

real(y_out)=data_I*coe_I-data_Q*coe_Q

image(y_out)=data_I*coe_Q+data_Q*coe_I

Send the image interference suppressed data to the anti-jamming processing part, use the space-time power inversion algorithm based on the linear constraint minimum variance criterion to suppress the interference, and send it to the software receiver to complete the capture tracking and navigation positioning.

The filter structure design of the digital processing part is shown in Figure 5. The influence of image interference on the received signal is eliminated through the design of a complex bandpass filter, and then the processed data is sent to the anti-interference processing part.

The space-time adaptive filtering technology of the array receiving antenna does not increase the number of array elements, and by adding K time delays to each array element, the two-dimensional joint interference suppression effect of time domain and space domain is formed. The increase in the number of antenna elements leads to an increase in cost, and the space-time adaptive filtering process can provide more degrees of freedom in anti-interference. In general, it is necessary to make a compromise between the two performances. On this basis, the dual-antenna-based Anti-jamming navigation receivers have been widely used.

Using the space-time power inversion algorithm based on the linear constraint minimum variance criterion, as shown in Figure 6 and Figure 7, under different broadband interference strengths, the number of trackable satellites after receiver acquisition and tracking before and after IQ imbalance improvement and Implementation effect of PRN20 satellite output carrier-to-noise ratio. The number of trackable satellites is caused by the AD9371 RF receiver for amplification, filtering, quadrature mixing, and analog-to-digital conversion after the useful signal and interference reach the uniform line array of the second array at the same time, and then sent to the digital processing unit to complete the IQ mismatch. Image interference suppression, acquired by the navigation receiver after anti-interference processing and tracking. The output carrier-to-noise ratio reflects the quality of the satellite navigation signal, which can be used to reflect the impact of IQ mismatch on the anti-jamming effect of the navigation receiver.

As shown in Figure 8, on the basis of simulation analysis, a physical test platform is built, and the BPSK modulated broadband signal is generated by the SIGLENT SDG6052X signal waveform generator, and sent to the signal generator SSG3032X-IQE to generate a given power Radio frequency interference is sent out through the transmitting antenna. At the receiving end, data acquisition is performed through a zero-IF architecture software radio hardware platform based on RF transceiver AD9371 and Zynq-7100 FPGA. A comparative analysis of the performance of the receiver based on the complex bandpass filter before and after the improvement verifies the superiority of the image interference suppression method proposed by the present invention in dealing with the IQ imbalance problem.

The above examples only give the improved results under the uniform linear array, and those skilled in the art will recognize that it is still applicable to other communication systems using the broadband radio frequency transceiver structure. For the mentioned navigation receiver, especially in the face of many interference environments, using the characteristics of interference signals to perform anti-interference processing, the implementation of the present invention can bring good interference processing effects and ensure anti-interference The high-efficiency anti-interference processing ability of the type navigation receiver is maintained in the complex electromagnetic environment.

In use, when the useful signal bandwidth is much lower than the channel bandwidth, the present invention can suppress image interference caused by IQ imbalance through parameter optimization and digital domain filter design on the basis of utilizing the advantages of the original hardware structure. First, according to the characteristics of the signal system such as the center frequency of the received signal and the bandwidth of the main peak of the signal, optimize the local oscillation frequency and sampling rate parameters of the navigation receiver of the zero-IF architecture software radio general platform, so as to solve the IQ of the original zero-IF architecture software radio general receiver platform. The imbalance causes the problem of image interference overlapping with the desired signal spectrum.

On the basis of not changing the original hardware platform, the present invention resets the local oscillation frequency f _lo and the sampling rate parameter F _s according to the signal system characteristics such as the center frequency of the received signal and the bandwidth of the main peak of the signal, so as to realize the spectrum separation of the useful signal and the image interference .

将正交混频部分的I、Q两路的幅度增益记为ΔG_i，相位偏差记为/>

最后经滤波、混频、模数转换后的信号为Further, assume that the single interference reaching the receiving antenna is denoted as

The amplitude gain of the I and Q channels of the quadrature mixing part is denoted as ΔG _i , and the phase deviation is denoted as />

Finally, the signal after filtering, mixing, and analog-to-digital conversion is

In the case of ideal channel characteristics, the single interference signal after filtering, quadrature down-conversion, and analog-to-digital conversion is

It can be seen that if the original parameters are set, when there is an IQ mismatch problem, an image interference will be generated on the other side of the symmetry between the original interference and the local oscillator frequency. From a perspective, it is necessary to provide more degrees of freedom to suppress interference, which will lead to a decrease in receiver performance for a navigation receiver with a limited number of array elements.

Compared with the superheterodyne receiver, the zero-IF receiver has low cost, high integration, and simple structure, but due to the influence of manufacturing errors, the image interference problem caused by IQ imbalance cannot be avoided. This method of directly down-converting the signal to the baseband will increase the number of degrees of freedom required for interference suppression due to the IQ mismatch caused by the zero-IF of the receiver in a strong interference environment, thereby affecting the anti-corrosion performance of the navigation receiver. Interference ability.

Most of the current receivers are programmable systems based on the software radio design of the zero-IF architecture. Without changing the hardware structure, by optimizing the parameters of the receiving end, the advantages of the zero-IF structure are used to suppress image interference.

Through the design of the present invention, the useful signal can be kept in the positive frequency part, and at the same time, the image interference is separated from the frequency spectrum of the useful signal, so that the image interference generated by IQ imbalance is moved to the negative frequency part away from the useful signal.

Then design a bandpass filter according to the frequency band where the useful signal is located. According to the actual system needs indicators, after setting the type, order, passband stopband frequency, passband stopband ripple and sampling rate and other parameter information of the real number bandpass filter, the Nth order coefficient of the bandpass filter is finally obtained, that is, finite The long unit impulse response h(n), which is spectrally symmetric.

The signal received from the radio frequency channel is a complex signal composed of two IQ channels. In order to suppress the image interference, the characteristics of the wide and other signal system are emphasized.

为了达到保留正频率部分以及抑制负频率部分的效果，将上述得到的滤波器系数进行一次希尔伯特变换，得到单位脉冲响应的解析信号/>

The frequency response corresponding to the real bandpass filter obtained above is

In order to achieve the effect of retaining the positive frequency part and suppressing the negative frequency part, the filter coefficients obtained above are subjected to a Hilbert transform to obtain the analytical signal of the unit impulse response />

从而达到对于有用信号的保留，以及对镜像干扰的抑制。不需像传统方法一样必须建立复杂的训练集信号来校正。The analytical signal has a one-sided spectrum,

So as to achieve the preservation of useful signals and the suppression of image interference. There is no need to establish complex training set signals for correction like traditional methods.

The present invention only slightly changes the software on the existing software and hardware resources, without changing the original zero-IF hardware structure. Utilizing the characteristics of the received signal, through the corresponding parameter setting, the separation of the image interference and the useful signal is realized while taking advantage of the zero-IF structure. The suppression of image interference is realized through subsequent cascaded complex band-pass filters, thereby eliminating the image interference problem caused by IQ imbalance. The invention is suitable for instructing the design of an anti-jamming navigation receiver, and maintains a high anti-jamming effect in the presence of jamming.

It should be noted that the unspecified parts of the present invention are prior art. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention The present invention can be realized in other specific forms; therefore, the above-described embodiments should be regarded as exemplary and non-restrictive in every respect, and the scope of the present invention is determined by the appended claims. It is not limited by the above description, so it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention, and any reference signs in the claims should not be regarded as limiting the content of the claims involved . Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (8)

1. The suppression system of mirror image interference in zero intermediate frequency framework software radio is characterized in that: the array receiving antenna comprises an array receiving antenna, a receiving parameter setting module, a radio frequency channel, a signal processing module and a software receiver, wherein signals received by the array receiving antenna sequentially pass through the receiving parameter setting module, the radio frequency channel, the signal processing module and the software receiver.

2. The system for suppressing image interference in software radio based on zero intermediate frequency architecture according to claim 1, wherein: the array receiving antenna is a multi-array element receiving antenna, and the arrangement mode of the multi-array element receiving antenna comprises an even linear array, a square array and a circular array arrangement mode.

3. The system for suppressing image interference in software radio based on zero intermediate frequency architecture according to claim 1, wherein: the radio frequency channel comprises a filtering module, an amplifying module, a quadrature frequency mixing module, a low-pass filtering module and an analog-to-digital conversion module.

4. The system for suppressing image interference in software radio based on zero intermediate frequency architecture according to claim 1, wherein: the signal processing module comprises a sampling module, a digital domain filtering processing module and a data storage module, wherein the digital domain filtering processing module comprises a complex band-pass filter.

5. The system for suppressing image interference in a zero Intermediate Frequency (IF) architecture software-based radio according to claim 4, wherein: and the real part and the imaginary part of the coefficient of the complex number band-pass filter are obtained by converting the real number band-pass filter to obtain an analytic function.

6. The system for suppressing image interference in software radio based on zero intermediate frequency architecture according to claim 1, wherein: the software receiver comprises an anti-interference processing module, an acquisition module and a tracking module.

7. The system and method for image rejection in zero intermediate frequency architecture software defined radio of claim 6, wherein: and the anti-interference processing module adopts a space-time power inversion algorithm based on a linear constraint minimum variance criterion to carry out interference suppression.

8. The method for suppressing the image interference in the zero intermediate frequency architecture software radio is characterized in that: the method comprises the following steps:

s1: the array receiving antenna receives satellite signals and interference from space, and each array element transmits the received signals to a software radio universal platform based on a radio frequency channel;

s2: according to the bandwidth B of the desired satellite signal _S And a center frequency f _s Signal system characteristics, realizing local oscillation frequency f of receiving end _lo And a sampling rate F _s Optimizing the setting, namely, the original local oscillation frequency is equal to the central frequency of the received signal, and configuring the local oscillation frequency to meet the requirement

Wherein f is _s Is the center frequency of the useful signal, B _s Is the useful signal bandwidth;

sampling rate F _s Satisfies the following conditions: f _s ＞2f _h Wherein f is _h The maximum frequency point is the main peak frequency width of the received signal;

the optimal parameter configuration of the local oscillation frequency and the sampling rate under different receiving signals can be obtained by meeting the conditions;

s3: signals received by the array receiving antenna are subjected to down-conversion and analog-to-digital conversion through a radio frequency channel to obtain digital domain signals, so that the mirror image signals are stripped;

s4: after the signals reach the signal processing module, the received I path data and Q path data are processed by a complex band-pass filter, only one pass band can only pass signals of a positive frequency band or a negative frequency band, after the analyzed signals are filtered, the frequency spectrums of the refined frequency bands f 1-f 2 are reserved, and the corresponding negative frequency domain part is suppressed, so that the influence of image interference on the anti-interference capability of the navigation receiver terminal is eliminated.

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