A radio frequency cancellation circuit and an anti-interference receiver

Abstract

The present invention discloses a radio frequency cancellation circuit and an anti-interference receiver. The radio frequency cancellation circuit includes a radio frequency phase detection circuit, a baseband filtering and processing circuit, and a vector modulation circuit; the baseband filtering and processing circuit includes an AD circuit, a DA circuit, and a microprocessor; the output signal of the radio frequency phase detection circuit is converted into a digital circuit by the AD circuit, and then digitally filtered and phase adjusted by the microprocessor, and then converted into a reference low-frequency baseband signal by the DA circuit. The anti-interference receiver adopts the radio frequency circuit to eliminate in-band interference. In the present invention, due to the use of software radio technology, through the microprocessor and the supporting circuit, the cancellation strategy can be adjusted in real time according to the spectrum form and signal bandwidth of the interference signal, so as to achieve a good adaptive cancellation effect.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency cancellation circuits, and in particular to a radio frequency cancellation circuit and an anti-interference receiver. Background Art

[0002] In the application of tactical radio multi-machine networking, due to the limited size of the vehicle, multiple transmitters and receivers are often arranged nearby. The RF radio receiver will inevitably be interfered by the transmission power of the local transmitter during operation. The interference of adjacent channels will reduce the signal-to-noise ratio of the receiving link, reduce the dynamic range of the RF link, and compress the gain of normal signals, thereby increasing the bit error rate; strong in-band interference may cause the receiver to enter a saturated state even if it is far away from the receiving channel, causing normal signals to be blocked and resulting in communication failure. Stronger interference may even burn out the receiver circuit. Therefore, wireless transceivers with multiple machines centrally arranged must consider the anti-interference ability of the circuit.

[0003] The direct leakage power of the transmitter can reach 15 to 20 dBm. At the same time, since the antennas of each radio station are arranged relatively concentratedly, the RF power coupled by the adjacent antennas may also reach the order of 20 dBm. This results in the receiver receiving a local transmission interference spectrum of 20 dBm when multiple radio stations are working at the same time. If the interference spectrum is not processed, such a high receiving power will cause the receiver to be blocked or even burn the sensitive receiver front end.

[0004] The most common countermeasure for interference is filtering, that is, suppressing the interference signal spectrum in the frequency domain. Frequency filtering technology is widely used in various types of receivers and has a good suppression effect on various types of out-of-band interference (including out-of-band self-interference). However, if the interference signal is close to or overlaps with the received target signal spectrum, interference suppression cannot be achieved through filtering and other methods. The second effective interference suppression method is vector cancellation technology. This method extracts a reference signal from the interference source, inverts the reference signal and injects it into the RF receiving channel. Since the injected signal is inverted with the original interference signal in the receiving channel, the interference signal is eliminated. Interference cancellation technology has a suppression effect on both in-band and out-of-band interference, and can adapt to changes in interference signals, and has no requirements for the spectrum of interference signals. The extraction of reference signals is an important part of interference cancellation technology. The quality of the reference signal directly affects the cancellation effect. When the interference signal is self-interference (or comes from a local transmitter), it is easy to extract the reference signal directly from the nearby transmission source.

[0005] Radio frequency interference cancellation technology has a wide range of applications, especially for suppressing local or local interference. When the spectrum of local interference is partially overlapped with or very close to the spectrum of useful signals, direct filtering methods cannot effectively suppress the interference without affecting the spectrum of useful signals. In addition, in some broadband multi-function transceivers, the frequency bands of transceiver signals vary within a wider frequency band, and conventional filtering methods often find it difficult to meet the designer's needs in terms of adaptability. In scenarios where filtering methods are not suitable, radio frequency self-interference cancellation technology has unique advantages. At present, typical applications of radio frequency self-interference cancellation technology include: single-antenna frequency-modulated continuous wave, full-duplex communication systems, and electromagnetic compatibility design of complex communication systems.

[0006] An important application area of ​​RF interference cancellation technology is the electromagnetic compatibility design of communication systems in some military equipment platforms. Modern electronic warfare platforms generally integrate high-power broadband jammers and wireless communication systems. When a high-power jammer is turned on, a considerable amount of interference signal will inevitably leak into the communication receiver. After the interference signal in the receiver passes through the RF filter, it appears as a bandpass white noise, which can be considered as a wide-sense stationary random signal. In order to ensure normal wireless communication functions, RF interference cancellation is required to suppress the noise interference of the same frequency, so as to achieve the purpose of not affecting the local communication while completing the external interference function.

[0007] Radio frequency interference cancellation technology is widely used in various types of continuous wave radars. As early as the 1960s, O'Hara and Moore first proposed a radio frequency interference cancellation system based on ferrite devices, which was applied in CW radar receivers. In 1988, PDL Beasley, AGStove and others developed a single-antenna FMCW radar that worked in the X-band and applied a reflected power canceller. The canceller used a vector modulator. The reference signal (i.e., the transmitted signal) and the error signal were orthogonally mixed, and then the control weight of the vector modulator was obtained through a low-pass filter. The canceller achieved a 30dB cancellation ratio within a bandwidth of 2GHz. Subsequent researchers used similar structures to develop a large number of vector cancellers in different frequency bands, established a standard cancellation model, and conducted theoretical research and experimental verification on the performance of vector cancellation. From 2004 to 2006, Kaihui Lin et al. from the University of California, USA, studied the vector cancellation used in Ka-band FMCW radar, analyzed the cancellation deterioration caused by the DC offset of the mixer in the classic vector cancellation, and used a heterodyne structure to eliminate the DC offset problem in the classic analog vector cancellation. The vector cancellation circuit achieved a 30dB cancellation ratio in the Ka-band and was successfully applied in a miniaturized synthetic aperture imaging radar, see [Kaihui Lin. Light Weight Millimeter Wave FMCW Radar System [D]. University of California, 2007]. In 2004, Jesh Grajal et al. from Spain developed an X-band FMCW radar. When the vector cancellation was at a sweep rate of 200MHz / ms, the cancellation ratio at 1GHz was greater than 30dB, see [Grajal J. et al. From a high-resolution LFM-CW shipborne radar to an airport surface detection]. In 2006, Jesh Grajal et al. analyzed the simplified model of vector cancellation and analyzed the stability of the system based on the closed-loop transfer function. The X-band vector cancellation designed based on this model achieved a cancellation ratio of 30 dB within a bandwidth of 200 MHz. See [Gonzalez M. et al. A detailed study and implementation of an RPC for LFM-CW radar [C]. European Radar Conference, 2006: 327-330].

[0008] Some domestic units have carried out research on reflection power cancellers. The University of Science and Technology of China, Xidian University, China Electronics Technology Group 54 and other units have conducted in-depth theoretical research and experiments. From 2011 to 2017, Xu Jun's research group at the University of Electronic Science and Technology of China developed a series of vector cancellation prototypes working in the Ka band. Under the conditions of a center frequency of 35 GHz and a sweep bandwidth of 200 MHz, the cancellation ratio of the vector cancellation reached 7 dB [Cheng Xinkai. Research on RF Cancellation Technology in Millimeter Wave FMCW Radar Guidance [D]. University of Electronic Science and Technology of China, 2011]. From 2013 to 2017, Xu Jinping's research group at the National Key Laboratory of Millimeter Waves at Southeast University developed vector cancellation prototypes based on hybrid integrated vector modulators for K-band and Ka-band. The static cancellation ratio of the K-band vector was greater than 16dB [Yan Ziliang. Research on K-band LFMCW radar RF power cancellation system [D]. Southeast University, 2013], and the static cancellation ratio of the Ka-band vector cancellation was greater than 20dB at 2GHz bandwidth [Fan Yanyan. Research on key technologies of millimeter-wave FMCW radar reflection power cancellation system [D]. Southeast University, 2014].

[0009] Conventional full-duplex communication cancellation circuits generally only cancel the interference signal of the local transmitter, but cannot cancel the interference signal of other local transmitters. Summary of the invention

[0010] Conventional full-duplex communication cancellation circuits generally only implement radio frequency cancellation for interference signals of local transmitters, and are unable to cancel interference signals of other local transmitters. The present invention provides a radio frequency cancellation circuit and an anti-interference receiver, which introduces a radio frequency interface of multiple reference signals in the receiver, forms a unified reference signal through a combiner, and then uniformly cancels interference signals of multiple transmitters through orthogonal phase detection, filtering and vector modulation.

[0011] The technical solution adopted by the present invention to achieve its technical purpose is: a radio frequency cancellation circuit, including a radio frequency phase detection circuit, a baseband filtering and processing circuit and a vector modulation circuit; the radio frequency input signal input from the radio frequency input port of the antenna and the reference signal input from the reference signal input port are respectively connected to the radio frequency phase detection circuit, the output signal of the radio frequency phase detection circuit is processed by the baseband filtering and processing circuit to form a reference low-frequency baseband signal, the reference low-frequency baseband signal and the reference signal are vector modulated by the vector modulation circuit to form a cancellation signal with an anti-phase to the interference signal and output from the output port; the baseband filtering and processing circuit includes an AD circuit, a DA circuit and a microprocessor; the output signal of the radio frequency phase detection circuit is converted into a digital circuit by the AD circuit, and then digitally filtered and phase adjusted by the microprocessor, and then converted into a reference low-frequency baseband signal by the DA circuit.

[0012] Furthermore, the above-mentioned radio frequency cancellation circuit also includes a radio frequency combiner for combining all the interference signals of the same frequency into a reference signal, and the output end of the radio frequency combiner is connected to the reference signal input end.

[0013] Furthermore, in the above-mentioned RF cancellation circuit: it also includes a 90-degree bridge that divides the reference signal into two orthogonal reference signals, and the RF phase detection circuit includes two groups of phase detectors; the input end of the 90-degree bridge is connected to the reference signal input end, the two-way orthogonal reference signal output end of the 90-degree bridge and the input signal divided into two paths are respectively connected to the input ends of the two groups of phase detectors, and the outputs of the two groups of phase detectors are respectively connected to the baseband filtering and processing circuit to output two orthogonal reference low-frequency baseband signals.

[0014] Furthermore, in the above-mentioned radio frequency cancellation circuit: it also includes a second reference signal input port for inputting a reference signal, and the vector modulation circuit includes two groups of vector modulators;

[0015] The reference signal is input from the second reference signal input port and then bridged by a 90-degree bridge into two orthogonal second orthogonal reference signals. The two second orthogonal reference signals and the two orthogonal reference low-frequency baseband signals are connected to the input end of the vector modulator, and the output ends of the two sets of vector modulators are added to form a cancellation signal.

[0016] The present invention also provides an anti-interference receiver, including a radio frequency cancellation circuit, wherein an input signal received by an antenna is coupled to a signal via a first coupler at an input port via the radio frequency cancellation circuit to generate a cancellation signal, and the cancellation signal is coupled to the input signal via a second coupler to form an input signal that eliminates co-frequency interference; the radio frequency cancellation circuit includes the above-mentioned radio frequency cancellation circuit.

[0017] Furthermore, the above-mentioned anti-interference receiver also includes a group of power combiners, which combine the output signals of all power amplifiers into one reference signal to be input into the reference signal input terminal of the RF cancellation circuit.

[0018] In the present invention, due to the use of software radio technology, through a microprocessor and supporting circuits, the cancellation strategy can be adjusted in real time according to the spectrum form and signal bandwidth of the interference signal to achieve a good adaptive cancellation effect.

[0019] In addition, a multi-channel reference signal RF interface is introduced into the receiver, a unified reference signal is formed through a combiner, and then the interference signals of multiple transmitters are uniformly cancelled through orthogonal phase detection, filtering and vector modulation.

[0020] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attached Figure 1 It is the schematic diagram of the RF cancellation circuit;

[0022] Attached Figure 2 The digital baseband conditioning circuit is used in Embodiment 1 of the present invention;

[0023] Attached Figure 3 is a block diagram of a radio frequency cancellation receiver in Embodiment 1 of the present invention;

[0024] Attached Figure 4 It is a frequency domain schematic diagram of RF cancellation according to Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0025] This embodiment is an anti-interference receiver in a tactical radio station, which has a radio frequency cancellation circuit and can eliminate co-frequency interference signals. In the case where there are multiple transmitter interference sources locally, the interference of all transmitters can be eliminated well.

[0026] like Figure 3 As shown, the anti-interference receiver in this embodiment has the following Figure 2 The RF cancellation circuit shown. In the anti-interference receiver, the input signal received by the antenna is coupled by the first coupler 18 of the input port A, and the cancellation signal is generated by the RF cancellation circuit. The cancellation signal is coupled to the input signal through the second coupler 19 to form an input signal that eliminates the same-frequency interference. The signal received by the antenna includes a useful received signal and an interference signal. The interference signal here is mainly the signal transmitted by the transmitter, including the RF signals transmitted by all the surrounding tactical radio transmitters. They will also be received by the antenna of the receiver. These signals need to be eliminated by the RF cancellation circuit.

[0027] like Figure 3 As shown, the reference signal is the signal emitted by the transmitters around the tactical radio station. Here, power amplifier 1 to power amplifier n represent the output signals of n transmitters, all of which will be received by the receiver and become co-frequency interference that needs to be eliminated by the RF cancellation circuit. Therefore, multiple power combiners 11 are used to combine them into one path to form a reference signal. The reference signal at B is divided into two paths at the reference signal input port through a splitter 12 and input from reference signal input ports B1 and B2 respectively. After B1 is input, it is also connected to two phase detectors 14 through a 90 bridge 13 respectively, while the reference signal input by B2 is divided into mutually orthogonal signals through a second 90 bridge 16 and enters two vector controllers 17.

[0028] In the two groups of phase detectors 14, the two input ends of one group of phase detectors 14 are the input signal and the reference signal respectively, and the input of the other phase detector 14 is the orthogonal signal of the input signal at A and the reference signal. Therefore, it can be said that one input of the two phase detectors 14 is two orthogonal reference signals. After conditioning, the baseband signals formed are also orthogonal baseband signals, which are respectively connected to the two groups of vector modulators 17 and vector modulated with the orthogonal reference signals formed after the second 90-degree bridge input from B2 to form cancellation signals output from C. Then, they are coupled with the input signal at A to form the receiving signal at D with the same-frequency interference signal eliminated.

[0029] like Figure 1 As shown, the RF cancellation circuit includes a RF phase detection circuit, a baseband filtering and processing circuit, and a vector modulation circuit; in this embodiment, a RF interface of multiple reference signals is introduced in the receiver, a unified reference signal is formed through a combiner, and then the interference signals of multiple transmitters are uniformly cancelled by orthogonal phase detection, filtering and vector modulation. The RF phase detection circuit includes a group of two phase detectors 14, the baseband filtering and processing circuit includes two groups of baseband conditioning circuits 15, and the vector modulation circuit includes two groups of vector modulators 17. Since the reference signal has different paths when entering, the reference signal input terminal can have a reference signal input terminal B and a reference signal input terminal B1. In addition, there is a 90-degree bridge, which bridges the reference signals input from the reference signal input terminal B and the reference signal input terminal B1 by 90 degrees to form two pairs of orthogonal reference signals.

[0030] The received signal input from the input port A is simultaneously connected to two phase detectors 14 and a pair of orthogonal reference signals output by the 90-degree bridge are processed in the phase detector 14 and then enter the baseband filtering and processing circuit to form two orthogonal baseband reference signals.

[0031] like Figure 2 As shown, the baseband filtering and processing circuit includes an AD circuit 151, a DA circuit 152 and a microprocessor 150; the output signal of the phase detector 14 is converted into a digital circuit by the AD circuit 151, and then digitally filtered and phase adjusted by the microprocessor 150, and then converted into a reference low-frequency baseband signal by the DA circuit 152. Here, the broadband RF signal output by the phase detector 14 is directly digitized, and digitally filtered and phase adjusted by the processor 150. The cancellation strategy can be adjusted in real time according to the spectrum form and signal bandwidth of the interference signal to achieve a good adaptive cancellation effect. At present, software radio technology is developing rapidly, and there are many modules that can be selected to implement baseband signal conditioning using software wireless technology.

[0032] In this embodiment, the interference cancellation circuit is a three-port network such as Figure 1As shown: Port A is the signal input port of the receiver, which comes from the antenna. The received signal contains useful signals and interference signals; Port B includes B1 and B2 as reference signal input ports. The reference signal is taken from the interference source. The local transmitter needs to reserve a coupling port. The coupled low-power transmission signal is used as the reference signal of the cancellation circuit. The reference signal is linearly transformed to obtain the inverted cancellation signal; Port C is the output port. The inverted cancellation signal is added to the received signal vector, and the inverted signal and the interference signal vector are offset. The residual error signal amplitude is extremely small, thereby achieving the reduction of the interference signal and will not affect the receiver's reception of useful signals. Conventional RF cancellation circuits such as Figure 1 shown.

[0033] The reference signal is expressed as J(ω)cos(ωt), where J(ω) is the modulation spectrum of the reference signal and ω is the carrier frequency. After the ninety-degree bridge power division, the two orthogonal reference signals are output as R1=J(ω)cos(ωt) and R2=J(ω)sin(ωt). The interference signal has the same spectrum as the reference signal, only the amplitude and phase are different. The amplitude can be compensated by conventional functional circuits such as amplifiers and attenuators. Therefore, the influence of the amplitude is ignored in the present invention, and only the phase difference is considered. Assume that the interference signal has the following form: J=J(ω)cos(ωt+θ), where θ is the phase of the interference signal. After the equal-amplitude and in-phase power division of the interference signal, it is phase-detected with the orthogonal reference signal respectively, and the phase-detected output is obtained as follows:

[0034] Filter out the high frequency component and ignore the amplitude component, and get the phase detection results of p1 = cos(θ) and p2 = -sin(θ). Invert the phase detection results and get the conditioned signals of p3 = -p1 = -cos(θ) and p4 = -p2 = sin(θ). Use the conditioned signals to modulate the two orthogonal branches of the reference signal, and finally add them together to get the cancellation signal:

[0035] C=J(ω)cos(ωt)·p3+J(ω)sin(ωt)·p4=-J(ω)cos(ωt+θ)

[0036] This process is called vector modulation. It can be seen that the cancellation signal is exactly inversely proportional to the interference signal, and the interference signal can be eliminated by vector addition.

[0037] In the cancellation receiver, the interference signal and the reference signal have the same source, and the only difference between them is the amplitude and phase, and the spectrum characteristics are the same. Therefore, the phase detection output signals of the two are low-frequency baseband signals, which contain information such as the amplitude and phase of the interference signal. The normal received signal is unrelated to the reference signal, so the phase detection output is a broadband noise spectrum, which can be eliminated by low-frequency filtering, and no effective phase detection output is generated.

[0038] like Figure 2 As shown in the figure, the core circuit of interference cancellation is a radio frequency phase detection circuit (including two phase detectors 14), a baseband filtering and processing circuit (including two groups of baseband conditioning circuits 15) and a vector modulation circuit (including two groups of vector modulators 17). The radio frequency phase detection circuit is used to compare the difference between the received interference signal and the reference signal. It is essentially a multiplier, that is, multiplying the interference signal with the reference signal, and the output low-frequency baseband signal contains all the difference information between the interference signal and the reference signal.

[0039] In the signal conditioning process, a low-pass filter and an inverting circuit are used, both of which can be implemented using analog circuits. However, considering that in the circuit layout, the transmission of the signal in the circuit takes a certain amount of time, which leads to Figure 1 The reference signals at the reference signal input port B1 and the reference signal input port B2 shown are not exactly the same. The two actually have a certain phase difference due to the difference in the length of the wiring. If the analog conditioning circuit is still used for processing, the cancellation signal is generated according to the vector modulation method shown in the above formula. The cancellation signal and the interference signal do not have a strict anti-phase phase, resulting in a large amount of residual interference after cancellation. For this reason, it is hoped that the conditioning circuit can adaptively adjust the amplitude of the conditioning signal according to the inherent signal wiring phase difference of the circuit, so as to compensate for the inherent phase difference by using vector modulation, so that the signal conditioning can be adaptively realized by using digital processing and microprocessor technologies, which has great flexibility.

[0040] Complex baseband filtering and processing circuits require the use of AD and DA circuits and microprocessors. First, the baseband signal is converted into a digital signal, and the microprocessor completes the filtering, phase adjustment and other functions, and then it is converted into a baseband signal through a DA converter. Simple filtering circuits have low flexibility, and their processing function is poor when the interference signal is more complex. The later vector cancellation effect is not good everywhere, and obvious residual signals are left. The processing circuit using a microprocessor is more complicated, but the system can adjust the processing algorithm in real time according to the characteristics of the interference signal, so that the interference cancellation is always in a good state. Using digital baseband conditioning circuits such as Figure 2 shown.

[0041] The baseband signal is digitized, and the microprocessor implements filtering, delay and signal conditioning. The processed baseband signal is then converted into an analog signal by a digital-to-analog converter, and an orthogonal two-way vector modulator forms a cancellation signal that is inversely proportional to the interference signal. The cancellation signal is injected into the receiver link through a directional coupler, and forms an anti-phase cancellation with the interference signal mixed in the normal received signal, purifying the spectrum of the received signal, eliminating the interference signal with a higher amplitude, and putting the receiver in a linear receiving range, ensuring that the receiver has normal gain, dynamic range and receiving sensitivity.

[0042] The RF cancellation circuit is insensitive to the number of interference sources, modulation methods, and interference paths, and is particularly suitable for canceling multipath interference and interference from multiple transmitters. The interference signal received by the receiver includes two paths, namely, the internal RF leakage path and the antenna close-coupled reception path. In view of the situation where there are multiple transmitter interference sources locally, the receiver needs to cancel the interference signals of multiple transmitters. The present invention introduces the transmission signals of each RF transmitter one by one, combines them into a reference signal through a RF combiner, and then uniformly uses RF cancellation to cancel the interference in the receiving link.

[0043] like Figure 4 As shown, from left to right are Figure 3 The schematic diagram of the spectrum of the anti-interference receiver shooting at points A, B, C, and D is shown, where point A represents the spectrum at the input of the receiver, including the useful received signal and three-way transmission interference signals; point B is the reference signal spectrum directly introduced by the transmitter; point C is the anti-phase cancellation signal spectrum generated after vector modulation; and D is the receiver signal spectrum after vector cancellation. In the figure, number 20 represents the receiver passband; 21 represents the normal received signal; 22 represents the interference spectrum of the local transmitter received by the receiver antenna; 23 represents the spectrum directly introduced by the local transmitter; 24 represents the inverted spectrum obtained after vector modulation; 25 and 26 represent the useful signal spectrum and interference spectrum after vector cancellation.

Claims

1. A radio frequency cancellation circuit, comprising a radio frequency phase detection circuit, a baseband filtering and processing circuit, and a vector modulation circuit; a radio frequency input signal input from a radio frequency input port (A) of an antenna and a reference signal input from a reference signal input port (B1) are respectively connected to the radio frequency phase detection circuit, an output signal of the radio frequency phase detection circuit is processed by a baseband filtering and processing circuit to form a reference low-frequency baseband signal, the reference low-frequency baseband signal and the reference signal are vector modulated by the vector modulation circuit to form a cancellation signal in anti-phase with an interference signal and output from an output port (C); characterized in that: The baseband filtering and processing circuit includes an AD circuit, a DA circuit and a microprocessor; the output signal of the radio frequency phase detection circuit is converted into a digital circuit by the AD circuit, and then digitally filtered and phase adjusted by the microprocessor, and then converted into the reference low-frequency baseband signal by the DA circuit. The radio frequency cancellation circuit also includes a radio frequency combiner that combines interference signals of the same frequency into a reference signal, and the output end of the radio frequency combiner is connected to the reference signal input end. By allowing the radio frequency combiner to form a unified reference signal, the interference signals of multiple transmitters are uniformly cancelled by orthogonal phase detection, filtering and vector modulation.

2. The radio frequency cancellation circuit according to claim 1, characterized in that: It also includes a 90-degree bridge that divides the reference signal into two orthogonal reference signals. The radio frequency phase detection circuit includes two groups of phase detectors. The input end of the 90-degree bridge is connected to the reference signal input end (B1), the two-way orthogonal reference signal output end of the 90-degree bridge and the input signal divided into two ways are respectively connected to the input ends of the two groups of phase detectors, and the outputs of the two groups of phase detectors are respectively connected to the baseband filtering and processing circuit to output two orthogonal reference low-frequency baseband signals.

3. The radio frequency cancellation circuit according to claim 2, characterized in that: It also includes a second reference signal input port (B2) for inputting the reference signal, and the vector modulation circuit includes two groups of vector modulators; after the reference signal is input from the second reference signal input port (B2), it is bridged by a 90-degree bridge to form two orthogonal second orthogonal reference signals, the two second orthogonal reference signals and the two orthogonal reference low-frequency baseband signals are connected to the input end of the vector modulator, and the output ends of the two groups of vector modulators are added to form a cancellation signal.

4. An anti-interference receiver, comprising a radio frequency cancellation circuit, wherein an input signal received by an antenna is coupled to a signal of a first coupler (18) of an input port (A) via the radio frequency cancellation circuit to generate a cancellation signal, and the cancellation signal is coupled to the input signal via a second coupler (19) to form an input signal that eliminates co-frequency interference; characterized in that: The radio frequency cancellation circuit comprises any one of the radio frequency cancellation circuits in claims 1 to 3.

5. The anti-interference receiver according to claim 4, characterized in that: It also comprises a group of power combiners (11), wherein the group of power combiners (11) combines the output signals of all power amplifiers into one reference signal to be input to the reference signal input terminal (B) of the radio frequency cancellation circuit.

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