CN111585594A - Interference cancellation device and method based on cascade digital control method - Google Patents

Abstract

The invention discloses an interference cancellation device and method based on a cascaded digital control method. The device comprises a digital radio frequency storage sub-system, a digitally controlled analog pair and elimination system, and a digitally controlled digital pair and elimination system; the digital radio frequency storage system The input end of the sub-system receives the co-located interference signal, performs digital processing on the co-located interference signal, estimates the delay matching error of the system, and performs delay matching processing; The two-stage cascade cancellation processing mode for co-located interference signals realizes suppression of co-located interference signals; the cancellation method includes the following steps: system initialization; a delay matching control unit estimates the system delay matching error, and performs delay matching processing; The co-located interference signal is subjected to two-stage interference cancellation processing; the canceled signal is output to the interfered receiver through the third radio frequency transmission chain, and finally the co-located interference signal is suppressed.

Description

Interference cancellation device and method based on cascade digital control method

technical field

The invention relates to the field of electromagnetic compatibility, in particular to an interference cancellation device and method based on a cascaded digital control method.

Background technique

At present, modern military platforms such as ships, aircraft, satellites and vehicles are usually densely deployed with multiple, multi-class RF transceivers; such RF transceivers are usually communication radio, data link, radar, navigation and positioning. systems, electronic warfare equipment, identification friend or foe systems and detection equipment, etc.

Among them, the electromagnetic energy emitted by the radio frequency transmitter in the radio frequency transceiver is often coupled to the radio frequency receiver in the same platform through radiation and conduction, forming interference to the radio frequency receiver, which is called co-site interference or Self-interference and co-site interference degrade or even fail the radio frequency receiver.

Suppressing the co-site interference of military platforms and realizing electromagnetic compatibility between radio frequency transceivers have urgent military needs and important military significance.

In the prior art, adaptive interference cancellation technology is an effective technical means to suppress co-site interference and realize electromagnetic compatibility between radio frequency transceivers of military platforms; The opposite signal is superimposed with the interference signal, thereby forming a canceling effect on the interference signal.

With the in-depth development of military platform informatization, the use of adaptive interference cancellation technology to achieve electromagnetic compatibility between radio frequency transceivers on military platforms faces new challenges. The existing adaptive interference cancellation technology exposes the following shortcomings: First, the current The interference cancellation system usually cannot intervene in the digital baseband part of the transceiver, and can only exchange signals with the external interface of the transceiver through the radio frequency cable. Second, the electromagnetic environment of the battlefield is complex and changeable, and the interference source and propagation of co-site interference The characteristics often have the characteristics of rapid change, and the ability of the existing interference cancellation system to quickly converge and fast track is insufficient. Third, military transceivers show the status and trend of broadband, and the interference cancellation system has insufficient ability to deal with broadband interference signals. Fourth, the high-sensitivity receiver faces high-power interference sources, and it is difficult for the interference cancellation system to provide sufficient interference suppression capability to suppress the interference to the vicinity of the receiver noise floor; fifth, the use of couplers to sample the interference signal, usually accompanied by insertion loss , reducing the effective operating range of the RF transmitter.

In order to solve the above problems, the patent application with the application number of CN201811155774.6 proposes a radio frequency cancellation device and method for digital domain interference reconstruction. The device includes digital delay, interference reconstruction model, coefficient identification algorithm, digital-analog Modules such as converter, cancellation link and combiner, wherein digital delay, interference reconstruction model and coefficient identification algorithm run on digital signal processing device; cancellation method includes the following steps: The interference reconstruction model is established based on the characteristics of the link cancellation; the digital delay is realized according to the received and received digital signals to align the received and received digital signals; the static coefficient identification of the model coefficients is realized by using the digital delay data and the received data; this technology solves the problem of broadband interference signals. However, the technical problem that exists is the need to intervene in the digital baseband part of the radio frequency transceiver.

In addition, the patent with the application number CN201010538860.2 proposes a co-located coupling interference tracking and cancellation device, which is composed of a directional coupler, an electronic modulation trap and a phase-locked loop circuit; the input end of the directional coupler is connected to the receiving end of the receiving The antenna is connected, the output end of the directional coupler is connected with the input end of the ESC trap, the coupling end of the directional coupler is connected with the input end of the phase-locked loop circuit; the output end of the ESC trap is connected with the receiver , the control end of the ESC trap is connected with the output end of the phase-locked loop circuit; this technology does not need to intervene in the digital baseband part of the RF transceiver, but the problems are that it is difficult to apply to broadband interference, and the convergence speed is slow.

Another patent with application number CN201320001505.0 proposes an adaptive wideband interference cancellation device, the device includes a first coupler, a time delay device and an adaptive cancellation system, wherein the adaptive cancellation system includes: phase shift adjustable attenuator, adjustable attenuator, correlator, coupler and synthesizer; the adjustable attenuator of the adaptive cancellation system is divided into the first and the second adjustable attenuator; the correlator is divided into the first and the second correlator; The couplers are divided into second and third couplers; this technology solves the problem of wideband interference signal cancellation, but the existing problem is that the interference signal sampling is accompanied by insertion loss, and the cancellation ratio and convergence speed are limited.

It can be seen from the above analysis that the existing technology cannot meet the stringent requirements of electromagnetic compatibility of military platform transceivers. Therefore, an interference cancellation device and method based on a cascaded digital control method are urgently needed to solve the existing technical problems.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide an interference cancellation device and method based on a cascaded digital control method, and introduce digital radio frequency storage technology into the interference cancellation system, so as to prevent the interference source signal (ie the reference signal) It has been digitized to solve the problem that the interference cancellation system is limited by the inability to intervene in the digital baseband part of the transmitter; the digital control analog counter-subversion system and the digitally controlled digital counter-subversion system are used to perform two-stage cascaded cancellation of co-site interference. processing to achieve fast and in-depth cancellation of broadband co-location interference.

The present invention is achieved through the following technical solutions.

An interference cancellation device based on a cascaded digital control method, comprising a digital radio frequency storage sub-system, a digitally controlled analog pairing and cancellation system, and a digitally controlled digital pairing and cancellation system; an input end of the digital radio frequency storage sub-system receives an interference source signal, digitally process the interference source signal, estimate the delay matching error of the system, and perform delay matching processing; the digitally controlled analog pair elimination system and the digitally controlled digital pair elimination system form a two-stage cascade for co-located interference signals Cancellation processing mode to suppress co-located interference signals.

Further, the digital radio frequency storage subsystem includes: a first radio frequency receiving chain, a first radio frequency transmitting chain, a digital delay module and a delay matching control unit;

The first radio frequency receiving link receives the interference source signal and converts the interference source signal into a digital signal to form a digital baseband signal, and transmits the digital baseband generated by the first radio frequency receiving link to the digital delay module and the delay matching control unit respectively;

The delay matching control unit estimates the system delay matching error according to the cross-correlation function between the two input signals, and then transmits the system delay matching error to the digital delay module;

The digital delay module performs delay processing on the interference source signal according to the system delay matching error input by the delay matching control unit, and transmits the processed signal to the first radio frequency transmission link;

The output end of the first radio frequency transmission chain is provided with a transmission output port, the output end of the transmission output port is provided with a transmission antenna, and the interference source signal subjected to the delay matching process is converted by the first radio frequency transmission chain into The analog signal is transmitted through the transmitting output port and the transmitting antenna.

Further, the digitally controlled analog-to-subtraction system controls the co-located interference signal in the digital signal domain and suppresses the co-located interference signal in the analog signal domain, and includes a second radio frequency receiving chain and a second radio frequency transmitting chain. circuit, analog cancellation digital control module and combiner;

The second radio frequency receiving link converts the analog radio frequency signal output from the combiner into a digital baseband signal, and sends it to the analog cancellation digital control module and the delay matching control unit;

The analog cancellation digital control module is a finite-length unit impulse response adaptive filter;

The analog cancellation digital control module receives the digital baseband signal generated by the first radio frequency receiving link and the digital baseband signal output by the second radio frequency receiving link, and forms the digital baseband signal of the first-level interference cancellation signal after calculation, and delivering the digital baseband signal of the first-level interference cancellation signal to the second radio frequency transmission chain;

The second radio frequency transmission chain converts the digital baseband signal of the first-level interference cancellation signal into an analog radio frequency signal of the first-level interference cancellation signal, and sends it to the combiner;

the combiner receives the co-located interference signal caused by the transmit antenna through the receive input port and the receive antenna;

The combiner superimposes the analog radio frequency signal of the first-level interference cancellation signal and the co-site interference signal, thereby canceling a part of the co-site interference signal;

The second radio frequency receiving chain, the second radio frequency transmitting chain, the analog cancellation digital control module and the combiner form a closed-loop computing system, which continuously iteratively cancels the co-site interference signal.

Further, the digitally controlled digital cancellation system controls and suppresses the co-located interference signal in the digital signal domain; it includes a third radio frequency transmission chain and a digitally controlled digital cancellation module;

The digital cancellation digital control module is composed of a linear filter, a memoryless nonlinear filter and a linear filter cascaded in sequence;

An input end of the digital cancellation digital control module receives the digital baseband signal output by the second radio frequency receiving link;

The other input end of the digital cancellation digital control module receives the digital baseband signal output by the first radio frequency receiving link;

After the digital control module operates on the two input signals, the second-level interference cancellation is completed, and the digital baseband signal after the interference cancellation is generated;

The input end of the third radio frequency transmission chain is connected with the output end of the digital cancellation digital control module, and the digital baseband signal after the second-level interference cancellation output by the digital cancellation digital control module is converted into an analog radio frequency signal;

The output end of the third radio frequency transmission chain is provided with a receiving output port, and the analog radio frequency signal is output through the receiving port.

The cancellation method of the interference cancellation device based on the cascade digital control method includes the following steps:

Step S1, the system is initialized; the output signal of the digitally controlled analog pairing and dividing system is set to zero, and the output signal of the second radio frequency transmission chain is also approximately zero at this time, and the digitally controlled analog pairing and dividing system temporarily does not play a role in suppressing co-site interference. the role of;

Step S2, the delay matching control unit in the digital radio frequency storage subsystem estimates the system delay matching error, and performs delay matching processing;

Step S3, using digital control simulation to perform first-level interference cancellation processing on the elimination system;

Step S4, using the digital control number to perform the second-level interference cancellation processing on the elimination system;

Step S5, the third radio frequency transmission link converts the digital baseband signal of the cancellation signal into an analog radio frequency signal, and outputs the signal through the receiving output port.

Further, in step S1, the delay time τ _DRFM of the digital delay module in the digital radio frequency storage subsystem is initialized to be τ ₀ :

τ ₀ =τ _RX1 +τ _DA +τ _TX3

Wherein, τ _RX1 is the delay of the first radio frequency receiving chain module, τ _DA is the delay of the analog cancellation digital control module, and τ _TX3 is the delay of the second radio frequency transmitting chain module.

Further, in step S2, the system delay matching error is the time difference Δτ between the interference source signal reaching the two input ports of the combiner:

Δτ=τ ₀ -τ ₁

Wherein τ ₁ =τ _RX1 +τ _DRFM +τ _TX1 +τ _coupling ; τ _TX1 is the delay of the first radio frequency transmission link, and τ _coupling is the transmission delay of the interference coupling from the transmitting antenna to the receiving antenna;

Further, by calculating the cross-correlation function of the output signal of the first radio frequency receiving chain and the output signal of the second radio frequency receiving chain, the time difference Λτ of the above two signals is obtained, because Λτ=τ _RX1 -(τ _RX1 +τ _DRFM +τ _TX1 +τ _coupling +τ _combiner +τ _RX2 ), so Δτ=Λτ+τ _DA +τ _TX3 -τ _combiner- τ _RX2 ; where τ _combiner is the delay of the combiner; τ _RX2 is the first The delay of two radio frequency receiving links; in the above formula, τ _DA , τ _TX3 , τ _combiner , τ _RX2 are known constant values of the device of the present invention, so the estimated value of Δτ can be obtained by obtaining the estimated value of Λτ; After the system delay matches the estimated value of the error Δτ, adjust the delay time τ _DRFM of the digital delay module to make Δτ zero.

其中，n表示数字信号的采样次序；d(n)为第二射频接收链路输出信号，作为自适应滤波器的期望信号；u(n)为第一射频接收链路输出信号，作为自适应滤波器的多抽头输入；

为n-1时刻自适应滤波器的系数。Further, in step S3, the output signal of the analog cancellation digital control module is

Among them, n represents the sampling order of the digital signal; d(n) is the output signal of the second radio frequency receiving chain, as the expected signal of the adaptive filter; u(n) is the output signal of the first radio frequency receiving chain, as the adaptive filter Multi-tap input to the filter;

is the coefficient of the adaptive filter at time n-1.

Further, in step S4, the digital cancellation digital control module is composed of a linear filter l(.), a memoryless nonlinear filter c(.) and a linear filter g(.) cascaded in sequence; let e(n) is the output signal of the digitally controlled digital pair-division system, v ₁ (n), v ₂ (n) are the input and output of the nonlinear filter c(.), respectively, then,

e(n)=d(n)-y(n)

Among them, ψ(n) is the input signal of the digitally controlled digital cancellation system; v ₁ (n) is the output signal of the linear filter l(.), that is, the input signal of the nonlinear filter c(.); l( i), i=0,..., M _l -1 is the coefficient of the linear filter l(.); M _l is the length of the linear filter l(.); v ₂ (n) is the nonlinear filter c (.) output signal, that is, the input signal of the linear filter g(.); c(p), p=0, ..., P is the coefficient of the linear filter c(.); P is the nonlinear filter is the maximum order of the filter c(.); y(n) is the output signal of the linear filter g(.); g(i), i=0,..., M _g -1 is the linear filter g(. ) coefficients; M _g is the length of the linear filter g(.).

Compared with the prior art, the beneficial effects of the present invention are:

1) The present invention introduces the digital radio frequency storage technology into the interference cancellation system for the first time, and performs digital processing on the interference source signal (that is, the reference signal), which solves the problem that the interference cancellation system is subject to the inability to intervene in the digital baseband part of the transmitter, so that the It is practical and feasible to apply digital control analog cancellation technology to co-site interference suppression;

2) The present invention utilizes the digital delay module and the delay matching control technology in the digital radio frequency storage technology to digitally delay the interference source signal, and solves the problem that the digital control analog cancellation technology cannot realize the delay matching in the application of suppressing the co-site interference. , so that the application of digital control analog cancellation technology to co-site interference suppression has practical feasibility;

3) The present invention utilizes the digital radio frequency storage technology to realize the reference sampling without insertion loss, and solves the problem that the traditional reference sampling process based on the coupler loses the transmitting power of the transmitter, thereby reducing the maximum working distance of the transmitter;

4) The present invention adopts a two-stage cascaded interference cancellation strategy and a digital control method, and the interference cancellation algorithm is very flexible, which is beneficial to improve the interference cancellation ratio, the interference cancellation convergence speed, the tracking speed and the interference cancellation bandwidth. etc., suitable for recovering weak useful signals in high-power broadband interference.

Description of drawings

Fig. 1 is the principle block diagram of the present invention;

Fig. 2 is the composition structure diagram of the first transmission chain of the present invention;

Fig. 3 is the composition structure diagram of the first radio frequency receiving link of the present invention;

Fig. 4 is the schematic diagram of using method of the present invention;

Detailed ways

The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

The present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings.

As shown in FIG. 1 , the interference cancellation device based on the cascaded digital control method proposed by the present invention includes: a digital radio frequency storage subsystem, a digitally controlled analog pairing and elimination system, and a digitally controlled digital pairing and elimination system;

The input end of the digital radio frequency storage subsystem receives the interference source signal (that is, the reference signal); the digital radio frequency storage subsystem digitizes the interference source signal, so that the interference cancellation system indirectly obtains the digital baseband signal of the radio frequency transmitter, and Estimate the system delay matching error, perform delay matching processing, and finally output the delayed interference source signal;

The digital control analog pair elimination system and the digital control digital pair elimination system form a two-stage cascaded cancellation processing mode for co-site interference signals;

The digitally controlled analog-to-subtraction system controls the interference source signal in the digital signal domain, and suppresses the co-located interference signal in the analog signal domain to avoid the quantization noise limitation of the analog-to-digital converter, and has broadband cancellation capability;

The digital control digital pair elimination system controls and suppresses the co-located interference signal in the digital signal domain. It uses digital signal processing technology and algorithm optimization design to accurately model and estimate the interference signal, and quickly suppress the co-located interference signal.

The digital radio frequency storage subsystem includes: a first radio frequency receiving chain, a first radio frequency transmitting chain, a digital delay module and a delay matching control unit;

The input end of the first radio frequency receiving chain is provided with a transmitting input port;

The first radio frequency receiving link receives the interference source signal through the transmission input port and digitizes the interference source signal to generate a digital baseband signal;

The first radio frequency receiving link transmits the digital baseband signal to the digital delay module and the delay matching control unit respectively;

The delay matching control unit estimates the system delay matching error according to the cross-correlation function between the output signal of the first radio frequency receiving chain and the output signal of the second radio frequency receiving chain, and then transmits the system delay matching error to the digital delay module;

The digital delay module performs delay processing on the interference source signal according to the system delay matching error input by the delay matching control unit, and transmits the processed signal to the first radio frequency transmission link;

the first radio frequency transmit chain simulates the input signal;

The output end of the first radio frequency transmission chain is provided with a transmission output port;

An output end of the transmitting output port is provided with a transmitting antenna;

The interference source signal processed by the delay matching is converted into an analog signal by the first radio frequency transmission chain and transmitted through the transmission output port and the transmission antenna.

The digitally controlled analog-to-cancellation system includes: a second radio frequency receiving chain, a second radio frequency transmitting chain, an analog-cancellation digital control module and a combiner;

The input end of the combiner is provided with a receiving input port;

The input end of the receiving input port is provided with a receiving antenna;

The receiving antenna receives the interference source signal output from the transmitting output port through the self-interference coupling path to form a co-located interference signal, and also receives useful signals sent from other radio frequency transmitters;

The other input end of the combiner is connected to the output end of the second radio frequency transmission chain;

The output end of the combiner is connected to the input end of the second radio frequency receiving chain;

The output end of the second radio frequency receiving chain is connected with the input end of the analog cancellation digital control module;

The other input end of the analog cancellation digital control module is connected to the first radio frequency receiving link, and receives the digital baseband signal output by the first radio frequency receiving link;

The output end of the analog cancellation digital control module is connected with the input end of the second radio frequency transmission chain;

The combiner receives the co-located interference signal caused by the transmitting antenna through the receiving input port and the receiving antenna;

The second radio frequency receiving link converts the analog radio frequency signal output from the combiner into a digital baseband signal, and sends it to the analog cancellation digital control module; the analog cancellation digital control module is a finite-length unit impulse response (FIR) adaptive filter;

The analog cancellation digital control module receives the digital baseband signal output by the first radio frequency receiving link and the digital baseband signal output by the second radio frequency receiving link, and forms the digital baseband signal of the first-level interference cancellation signal after calculation, and converts the digital baseband signal to the first-level interference cancellation signal. The digital baseband signal of the first-level interference cancellation signal is sent to the second radio frequency transmission chain;

The second radio frequency transmission chain converts the digital baseband signal of the first-level interference cancellation signal into an analog radio frequency signal of the first-level interference cancellation signal, and sends it to the combiner;

The combiner superimposes the analog radio frequency signal of the first-level interference cancellation signal and the co-site interference signal, thereby canceling a part of the co-site interference signal;

The second radio frequency receiving chain, the second radio frequency transmitting chain, the analog cancellation digital control module and the combiner form a closed-loop computing system, which continuously iteratively cancels the co-site interference signal.

The digitally controlled digital cancellation system includes: a third radio frequency transmission chain and a digitally controlled digital cancellation module;

The digital cancellation digital control module is composed of a linear filter, a memoryless nonlinear filter and a linear filter cascaded in sequence;

The input end of the digital cancellation digital control module is connected to the other output end of the second radio frequency receiving chain, and receives the digital baseband signal output by the second radio frequency receiving chain;

The other input end of the digital cancellation digital control module is connected to an output end of the first radio frequency receiving chain, and receives the digital baseband signal output by the first radio frequency receiving chain;

After the digital control module operates on the two input signals, the second-level interference cancellation is completed, and the digital baseband signal after the interference cancellation is generated. At this time, the co-site interference signal after the two-stage cancellation is further suppressed;

The input end of the third radio frequency transmission chain is connected with the output end of the digital cancellation digital control module, and the digital baseband signal after the second-level interference cancellation output by the digital cancellation digital control module is converted into an analog radio frequency signal;

The output end of the third radio frequency transmission chain is provided with a receiving output port, and the analog radio frequency signal is output through the receiving port.

As shown in FIG. 2 , the first radio frequency receiving chain includes: a low noise amplifier, a mixer, an operational amplifier, an analog filter, an analog-to-digital converter (ADC), a half-band filter (HBF) and a digital filter ; The low-noise amplifier, mixer, operational amplifier, analog filter, analog-to-digital converter (ADC), half-band filter (HBF) and digital filter are electrically connected in sequence, or some of them are composed according to functional requirements. The devices are cascaded in sequence;

Low noise amplifiers, mixers, operational amplifiers, analog filters, analog-to-digital converters (ADCs), half-band filters (HBFs), and digital filters together form an RF receive chain whose function is to pass the analog RF signal through After power adjustment, frequency domain filtering, and downconversion, it is converted into a digital baseband signal.

The structure of the second radio frequency receiving chain is the same as that of the first radio frequency receiving chain.

As shown in FIG. 3 , the first radio frequency transmission chain includes: a digital filter, a half-band filter (HBF), a digital-to-analog converter (DAC), an analog filter, a mixer and a power amplifier; the filter The device, half-band filter (HBF), digital-to-analog converter (DAC), analog filter, mixer and power amplifier are electrically connected in sequence, or some of the components are cascaded in sequence according to functional requirements;

The structures of the second radio frequency transmission chain and the third radio frequency transmission chain are the same as those of the first radio frequency transmission chain;

Digital filter, half-band filter (HBF), digital-to-analog converter (DAC), analog filter, mixer and power amplifier together form a radio frequency transmission chain, its function is to filter the digital baseband signal in the frequency domain, After up-conversion and power adjustment, it is converted into an analog RF signal.

The first radio frequency receiving chain, the second radio frequency receiving chain, the first radio frequency transmitting chain, the second radio frequency transmitting chain and the third radio frequency transmitting chain are all integrated with gain control capability.

Wherein, the first radio frequency receiving chain, the second radio frequency receiving chain, the first radio frequency transmitting chain, the second radio frequency transmitting chain, the third radio frequency transmitting chain and the combiner exist in the form of hardware;

The digital delay module, delay matching control unit, analog-cancellation digital control module and digital-cancellation digital control module use logic code or exists in the form of software code.

The interference cancellation method based on the cascaded digital control method includes the following steps:

Step S1, system initialization;

The output signal of the digitally controlled analog-to-subtraction system is set to zero, and the output signal of the second RF transmission chain is also approximately zero at this time; the digitally-controlled analog-to-subtraction system temporarily does not play a role in suppressing co-site interference;

Initialize the delay time τ _DRFM of the digital delay module in the digital radio storage subsystem as τ ₀ :

τ ₀ =τ _RX1 +τ _DA +τ _TX3

Wherein, τ _RX1 is the delay of the first radio frequency receiving chain module, τ _DA is the delay of the analog cancellation digital control module, and τ _TX3 is the delay of the second radio frequency transmitting chain module;

Step S2, the delay matching control unit in the digital radio frequency storage subsystem estimates the system delay matching error, and performs delay matching processing;

The system delay matching error is the time difference Δτ between the interference source signal reaching the two input ports of the combiner;

Δτ=τ ₀ -τ ₁

Wherein τ ₁ =τ _RX1 +τ _DRFM +τ _TX1 +τ _coupling ; τ _TX1 is the delay of the first radio frequency transmission link, and τ _coupling is the transmission delay of the interference coupling from the transmitting antenna to the receiving antenna;

The time difference Λτ of the above two signals is obtained by calculating the cross-correlation function of the output signal of the first radio frequency receiving chain and the output signal of the second radio frequency receiving chain, because

Λτ=τ _RX1 -(τ _RX1 +τ _DRFM +τ _TX1 +τ _coupling +τ _combiner +τ _RX2 )

So Δτ=Λτ+τ _DA +τ _TX3 -τ _combiner- τ _RX2

Among them, τ _combiner is the delay of the combiner; τ _RX2 is the delay of the second radio frequency receiving chain; in the above formula, τ _DA , τ _TX3 , τ _combiner , τ _RX2 are the known constants of the device of the present invention. value, so the estimated value of Δτ can be obtained by obtaining the estimated value of Δτ;

After obtaining the estimated value of the system delay matching error Δτ, adjust the delay time τ _DRFM of the digital delay module to make Δτ zero.

Step S3, using digital control simulation to perform first-level interference cancellation processing on the elimination system;

其中，n表示数字信号的采样次序；d(n)为第二射频接收链路输出信号，作为自适应滤波器的期望信号；u(n)为第一射频接收链路输出信号，作为自适应滤波器的多抽头输入；

为n-1时刻FIR自适应滤波器的系数；常用的自适应滤波器的控制算法有：最小均方误差(LMS)算法，归一化LMS算法，递归最小二乘(RLS)算法，卡尔曼滤波算法等。The analog-cancellation digital control block is a finite-length unit impulse response (FIR) adaptive filter whose output signal

Among them, n represents the sampling order of the digital signal; d(n) is the output signal of the second radio frequency receiving chain, as the expected signal of the adaptive filter; u(n) is the output signal of the first radio frequency receiving chain, as the adaptive filter Multi-tap input to the filter;

is the coefficient of the FIR adaptive filter at time n-1; the commonly used adaptive filter control algorithms are: Least Mean Square Error (LMS) algorithm, normalized LMS algorithm, recursive least squares (RLS) algorithm, Kalman filtering algorithms, etc.

The main purpose of using the FIR adaptive filtering algorithm as the core algorithm of the digitally controlled analog pairing and dividing system is to suppress the linear component in the co-site interference, reduce the interference signal ratio, and prevent the interference signal ratio from being larger than the dynamic signal of the ADC device in the second RF receiving chain. range; this step can also take a variety of other control and filtering methods.

Step S4, using the digital control number to perform the second-level interference cancellation processing on the elimination system;

The digital cancellation digital control module is composed of a linear filter l(.), a memoryless nonlinear filter c(.), and a linear filter g(.) cascaded in sequence; let e(n) be a number Control the output signal of the digital pair elimination system, v ₁ (n), v ₂ (n) are the input and output of the nonlinear filter c(.) respectively, then,

e(n)=d(n)-y(n)

Among them, ψ(n) is the input signal of the digitally controlled digital cancellation system; v ₁ (n) is the output signal of the linear filter l(.), that is, the input signal of the nonlinear filter c(.); l( i), i=0,..., M _l -1 is the coefficient of the linear filter l(.); M _l is the length of the linear filter l(.); v ₂ (n) is the nonlinear filter c (.) output signal, that is, the input signal of the linear filter g(.); c(p), p=0, ..., P is the coefficient of the linear filter c(.); P is the nonlinear filter is the maximum order of the filter c(.); y(n) is the output signal of the linear filter g(.); g(i), i=0,..., M _g -1 is the linear filter g(. ) coefficients; M _g is the length of the linear filter g(.).

Step S5, the third radio frequency transmission link converts the digital baseband signal of the cancellation signal into an analog radio frequency signal, and outputs the signal through the receiving output port.

The use method of the interference cancellation device based on the cascaded digital control method disclosed in the present invention is shown in FIG. 4 ; the transmitter is the interference source, and the receiver is the interfered device;

The transmitter is connected to the transmitting input port;

The receiver is connected to the receiving output port;

The interference source signal output by the transmitter enters the device through the transmitting input port. After the co-located interference signal and the useful signal are canceled by the device, the co-located interference signal is suppressed, and the useful signal is sent to the receiver from the receiving output port.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or some or all of the technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.

Claims (10)

1. An interference cancellation device based on a cascade digital control method is characterized by comprising a digital radio frequency storage subsystem, a digital control analog cancellation subsystem and a digital control digital cancellation subsystem; the input end of the digital radio frequency storage subsystem receives an interference source signal, digitalizes the interference source signal, estimates a system delay matching error and performs delay matching processing; the digital control analog cancellation subsystem and the digital control digital cancellation subsystem form a two-stage cascade cancellation processing mode for the co-located interference signals, and the co-located interference signals are suppressed.

2. The apparatus of claim 1, wherein the digital radio frequency memory subsystem comprises: the system comprises a first radio frequency receiving link, a first radio frequency transmitting link, a digital delay module and a delay matching control unit;

the first radio frequency receiving link receives an interference source signal and converts the interference source signal into a digital signal to form a digital baseband signal, and the digital baseband signal generated by the first radio frequency receiving link is respectively transmitted to the digital delay module and the delay matching control unit;

the delay matching control unit estimates a system delay matching error according to a cross-correlation function between the output signal of the first radio frequency receiving link and the output signal of the second radio frequency receiving link, and then transmits the system delay matching error to the digital delay module;

the digital delay module carries out delay processing on the interference source signal according to the system delay matching error input by the delay matching control unit and transmits the processed signal to a first radio frequency transmitting link;

the output end of the first radio frequency transmission link is provided with a transmission output port, the output end of the transmission output port is provided with a transmission antenna, and the interference source signal subjected to the delay matching processing is converted into an analog signal by the first radio frequency transmission link and is transmitted out through the transmission output port and the transmission antenna.

3. The interference cancellation device based on the cascaded digital control method according to claim 2, wherein the digital control analog cancellation subsystem controls the co-located interference signal in the digital signal domain and suppresses the co-located interference signal in the analog signal domain, and includes a second rf receiving link, a second rf transmitting link, an analog cancellation digital control module and a combiner;

the second radio frequency receiving link converts the analog radio frequency signal output from the combiner into a digital baseband signal and transmits the digital baseband signal to the analog cancellation digital control module and the delay matching control unit;

the analog cancellation digital control module is a finite length single-bit impulse response adaptive filter;

the analog cancellation digital control module receives a digital baseband signal generated by the first radio frequency receiving link and a digital baseband signal output by the second radio frequency receiving link, forms a digital baseband signal of a first-stage interference cancellation signal after operation, and transmits the digital baseband signal of the first-stage interference cancellation signal to the second radio frequency transmitting link;

the second radio frequency transmitting link converts the digital baseband signal of the first-stage interference cancellation signal into a first-stage interference cancellation signal analog radio frequency signal and transmits the first-stage interference cancellation signal analog radio frequency signal to the combiner;

the combiner receives the co-location interference signal caused by the transmitting antenna through a receiving input port and a receiving antenna;

the combiner superposes the analog radio frequency signal of the first-stage interference cancellation signal and the co-location interference signal, so as to cancel a part of the co-location interference signal;

the second radio frequency receiving link, the second radio frequency transmitting link, the analog cancellation digital control module and the combiner form a closed loop operation system, and continuous iteration cancellation is carried out on the co-location interference signals.

4. The interference cancellation device based on the cascaded digital control method according to claim 3, wherein the digital control digital cancellation subsystem controls and suppresses the co-located interference signals in a digital signal domain; the digital control digital cancellation module comprises a third radio frequency transmission link and a digital control digital cancellation module;

the digital cancellation digital control module is formed by cascading a linear filter, a memoryless nonlinear filter and a linear filter in sequence;

one input end of the digital cancellation digital control module receives a digital baseband signal output by the second radio frequency receiving link;

the other input end of the digital cancellation digital control module receives a digital baseband signal output by the first radio frequency receiving link;

after the digital cancellation digital control module operates the two input signals, second-stage interference cancellation is completed, and digital baseband signals after the interference cancellation are generated;

the input end of the third radio frequency transmission link is connected with the output end of the digital cancellation digital control module, and the digital baseband signal after the second-stage interference cancellation output by the digital cancellation digital control module is converted into an analog radio frequency signal;

and the output end of the third radio frequency transmission link is provided with a receiving output port, and the analog radio frequency signal is output through the receiving port.

5. The cancellation method of the interference cancellation device based on the cascaded digital control method according to claim 1, comprising the steps of:

step S1, initializing the system; the output signal of the digital control analog cancellation subsystem is zero, the output signal of the second radio frequency transmission link is also approximate to zero at the moment, and the digital control analog cancellation subsystem does not play a role in restraining co-location interference temporarily;

step S2, the delay matching control unit in the digital radio frequency storage subsystem estimates the system delay matching error and carries out the delay matching processing;

step S3, using digital control analog cancellation subsystem to process the first-stage interference cancellation;

step S4, using digital control digital cancellation subsystem to process the second interference cancellation;

in step S5, the third rf transmitting link converts the digital baseband signal of the cancellation signal into an analog rf signal, and outputs the analog rf signal through the receiving output port.

6. The method of claim 5, wherein in step S1, the delay time τ of the digital delay module in the digital RF storage subsystem is initialized_DRFMIs tau₀：

τ₀＝τ_RX1+τ_DA+τ_TX3

Wherein, tau_RX1For the delay of the first RF receiving chain, τ_DAFor analog cancellation of delay of the digital control block, tau_TX3Is the delay of the second radio frequency transmit chain.

7. The method of claim 5, wherein in step S2, the system delay matching error is the time difference Δ τ between the arrival of the aggressor signal at the two input ports of the combiner:

Δτ＝τ₀-τ₁

wherein tau is₁＝τ_RX1+τ_DRFM+τ_TX1+τ_{Coupling of}；τ_TX1For the delay of the first radio frequency transmission chain, tau_{Coupling of}To interfere with the transmission delay coupling from the transmit antenna to the receive antenna.

8. The method of claim 7, wherein the time difference Λ τ is obtained by calculating the cross-correlation function of the first RF receiving chain output signal and the second RF receiving chain output signal, because Λ τ is equal to τ_RX1-(τ_RX1+τ_DRFM+τ_TX1+τ_{Coupling of}+τ_Combiner+τ_RX2) Therefore, Δ τ is Λ τ + τ_DA+τ_TX3-τ_Combiner-τ_RX2(ii) a Wherein, tau_CombinerIs the delay of the combiner; tau is_RX2Delay for the second radio frequency receive chain; in the above formula, τ_DA,τ_TX3,τ_Combiner,τ_RX2The device of the invention has known constant value, therefore the estimated value of Λ tau can be obtained to obtain the estimated value of delta tau, after the estimated value of the system delay matching error delta tau is obtained, the delay time tau of the digital delay module is adjusted_DRFMLet Δ τ be zero.

9. The method of claim 5, wherein in step S3, the output signal of the analog cancellation digital control module is

Wherein n represents a sampling order of the digital signal; d (n) is the output signal of the second radio frequency receiving chain and is used as the expected signal of the self-adaptive filter; u (n) is the output signal of the first radio frequency receiving link and is used as the multi-tap input of the self-adaptive filter;

the coefficients of the adaptive filter at time n-1.

10. The method according to claim 5, wherein in step S4, the digital cancellation digital control module is formed by cascading a linear filter l (), a memoryless non-linear filter c (), and a linear filter g () in sequence; let e (n) be the output signal of the digital control digital cancellation subsystem, v₁(n),v₂(n) are the input and output, respectively, of the non-linear filter c (then,

e(n)＝d(n)-y(n)

wherein psi (n) is an input signal of the digital control digital cancellation system; v. of₁(n) is the output signal of the linear filter i (i), i.e. the input signal of the non-linear filter c (i); l (i), i ═ 0., M_l-1 is the coefficient of the linear filter l (); m_lIs the length of the linear filter l (.); v. of₂(n) is the output signal of the non-linear filter c (i.e., the input signal of the linear filter g.); c (P), P being 0, P being the coefficient of the linear filter c (); p is the maximum order of the nonlinear filter c (.); y (n) is a linear filter g (n)Output signal of.); g (i), i ═ 0.., M_g-1 is the coefficient of the linear filter g (); m_gIs the length of the linear filter g (.).

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