Anti-interference receiving system of smart navigation receiver based on dual antennas

Abstract

The present application relates to an anti-interference receiving system for a smart navigation receiver based on dual antennas. The system comprises: a receiving antenna installed in a skyward direction and a reference antenna installed in a groundward direction; the signal received by the receiving antenna is a navigation signal; the signal received by the reference antenna is a reference interference signal; a radio frequency interference cancellation module is provided; the reference interference signal is input into the radio frequency interference cancellation module for amplitude and phase adjustment, interference cancellation is performed on the reference interference signal after amplitude and phase adjustment and the signal received by the receiving antenna, and the navigation signal after interference cancellation is sent to the navigation receiving module for navigation signal reception and processing. This system can achieve anti-interference navigation for smart unmanned aerial vehicles.

Description

Technical Field

[0001] The present application relates to the field of satellite navigation technology, and in particular to an anti-interference receiving system of a smart navigation receiver based on dual antennas. Background Art

[0002] With the rapid development of drone technology, its application areas are becoming increasingly broad. Drones rely on satellite navigation systems for navigation during operation. However, due to the low power of navigation signals reaching the ground and the low operating altitude of drones, they are extremely susceptible to malicious interference from the ground, resulting in large positioning errors or even loss of positioning. Currently used satellite navigation anti-interference technologies domestically and internationally mainly include frequency domain filtering anti-interference technology, time domain filtering anti-interference technology, spatial domain filtering anti-interference technology, and space-time adaptive filtering anti-interference technology. However, all of these technologies are implemented through antenna arrays or dedicated anti-interference modules. These technologies either use relatively complex antenna arrays or dedicated anti-interference processors, which are large in size, weight, power consumption, and cost, making them unsuitable for small drones. Summary of the Invention

[0003] Based on this, it is necessary to provide an anti-interference receiving system for a smart navigation receiver based on dual antennas that can achieve anti-interference of smart UAV navigation in order to address the above technical problems.

[0004] A dual-antenna-based smart navigation receiver anti-interference receiving system, comprising a receiving antenna installed in a skyward direction, a reference antenna installed in a groundward direction, a radio frequency interference cancellation module, and a navigation receiving module;

[0005] The receiving antenna is used to receive the navigation signal; the reference antenna is used to receive the reference interference signal;

[0006] The radio frequency interference cancellation module is used to adjust the amplitude and phase of the reference interference signal, and perform interference cancellation on the reference interference signal after amplitude and phase adjustment with the signal received by the receiving antenna to obtain a navigation signal after interference cancellation;

[0007] The navigation receiving module is used to perform navigation signal reception processing on the navigation signal after interference cancellation.

[0008] The above-mentioned dual-antenna-based agile navigation receiver anti-interference receiving system adopts a dual-antenna-based RF analog cancellation scheme, and the present application adjusts the amplitude and phase characteristics of the interference signal received on the reference antenna according to the correlation between the received signals of different antennas, eliminates the interference signal superimposed on the receiving antenna, and achieves the anti-interference purpose. The antenna installation position is not restricted, and there is no need to have strict restrictions on the installation position of the sub-antenna like the anti-interference antenna array, so it is more versatile; and the cost of the components used in the hardware solution of the set RF interference cancellation module is relatively low, which can effectively control the cost; the analog cancellation scheme is adopted, and the types of interference signals suppressed are wider, not limited to specific interference types, and it also has a better suppression effect on broadband interference signals that are difficult to suppress with traditional anti-interference algorithms, and can realize anti-interference of agile unmanned aerial vehicle navigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 FIG1 is a schematic diagram of a framework of an anti-interference receiving system of a smart navigation receiver based on dual antennas in one embodiment;

[0010] Figure 2 A schematic diagram of an interference cancellation control flow in one embodiment;

[0011] Figure 3 1 is a flow chart of a detailed process of interference cancellation in one embodiment;

[0012] Figure 4 This is a spectrum diagram before cancellation of wideband interference with a bandwidth of 10 MHz in another embodiment;

[0013] Figure 5 FIG. 1 is a spectrum diagram after cancellation of wideband interference with a bandwidth of 10 MHz in one embodiment. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0015] In one embodiment, Figure 2 As shown, a dual-antenna-based smart navigation receiver anti-interference receiving system is provided, comprising:

[0016] A receiving antenna is installed in the direction facing the sky and a reference antenna is installed in the direction facing the ground; the signal received by the receiving antenna is the navigation signal; the signal received by the reference antenna is the reference interference signal.

[0017] Traditional anti-interference antenna arrays have strict requirements on the installation position of sub-antennas. This is because the working principle of the antenna array is based on the specific spatial layout and signal processing method between multiple antennas to achieve anti-interference function. The present application sets up a dual antenna group, which consists of two identical antennas. One is installed in the direction of the sky as a receiving antenna, and the corresponding received signal is used as a navigation signal; the other is installed in the direction of the ground as a reference antenna, and the corresponding received signal is used as a reference interference signal. Taking into account the interference cancellation effect, the parameters of the two antennas should be kept as consistent as possible. And their installation positions do not need to be precisely coordinated with other antennas like antenna arrays to implement specific anti-interference algorithms. This installation method is more flexible. Whether it is installed on different models of drones or in different parts of drones, as long as the basic direction requirements of the receiving antenna to the sky and the reference antenna to the ground are guaranteed, it can work normally, so it is more versatile.

[0018] A radio frequency interference cancellation module is set up; a reference interference signal is input into the radio frequency interference cancellation module for amplitude adjustment and phase adjustment, interference cancellation is performed on the reference interference signal after amplitude and phase adjustment and the signal received by the receiving antenna, and the navigation signal after interference cancellation is sent to the navigation receiving module for navigation signal reception processing.

[0019] The RF interference cancellation module consists of a digitally controlled attenuator, a power divider and phase shifter, an IQ vector modulator, a microcontroller, a power measurement module, a combiner, and a splitter. The digitally controlled attenuator adjusts the amplitude of the reference interference signal, while the IQ vector modulator adjusts its phase. After passing through the digital attenuator, the reference interference signal enters the power divider and phase shifter, outputting two orthogonal signals to the IQ vector modulator, which adjusts the phase of the reference interference signal. After phase and power adjustment, the reference interference signal is combined with the signal input from the other antenna and output to the power measurement module for power estimation. The microcontroller reads the power and adjusts the amplitude and phase of the reference interference signal to cancel it out with the interference signal received by the receiving antenna, eliminating the interference signal's impact on navigation signal reception. The signal is then sent to the navigation receiver module for processing.

[0020] Traditional anti-interference technologies sometimes utilize dedicated anti-interference processors, such as FPGAs (field-programmable gate arrays). FPGAs are high-performance programmable logic devices with powerful parallel processing capabilities and high flexibility, enabling the implementation of complex digital signal processing algorithms. However, FPGAs are relatively expensive due to their complex manufacturing process and high R&D and production costs. In contrast, the hardware solution employed in this application utilizes lower-cost components. For example, the controller can be implemented using a microprocessor such as a single-chip microcomputer (MCU). A MCU is a relatively low-cost microcontroller that integrates basic functional components such as a CPU, memory, and input / output interfaces. By using a low-cost microprocessor such as a MCU to control components such as the RF interference cancellation module, hardware costs can be effectively controlled without sacrificing anti-interference performance.

[0021] The RF cancellation process involves two search dimensions: 1) Phase search: The I and Q phases of vector modulation are determined by the phase. The search begins by searching the I and Q phase values. By stepping the phase values, the phase value corresponding to the minimum power is selected based on the power estimation results as the initial phase search result. 2) Gain search: Based on the obtained phase search value, the gain value is searched. Based on the power estimation results, the phase value corresponding to the minimum power is selected as the initial gain search result.

[0022] Because navigation signals have a low landing level and are often submerged in noise, while interference signals are typically higher in power, when interference and useful navigation signals coexist, the interference is suppressed and the navigation signal is not significantly affected. Furthermore, for drones, the interference source is typically on the ground, so the interference signal has a negative elevation angle. The reference antenna is mounted toward the ground, allowing it to receive a stronger interference signal as a reference signal. The receiving antenna is mounted toward the sky, providing some suppression of ground interference signals entering at negative elevation angles. Combining these two antennas effectively implements a simulated cancellation solution.

[0023] Compared with traditional anti-interference technologies, such as frequency domain filtering anti-interference technology, by analyzing the differences between the interference signal and the navigation signal in the frequency domain, a filter is designed to filter out the interference signal. This technology has a better suppression effect on interference signals with more obvious frequency characteristics, but for broadband interference signals, due to their wide frequency range, they may cover the frequency range of the navigation signal, and it is difficult to effectively separate the interference signal and the navigation signal using frequency domain filtering. Time domain filtering anti-interference technology mainly performs interference suppression based on the characteristics of the signal in the time domain. It is effective for some interference signals with specific time characteristics, but it also has limitations for complex and changeable broadband interference signals. The present application uses a radio frequency interference cancellation module to adjust the amplitude and phase of the reference interference signal, and then cancels the interference with the signal received by the receiving antenna. This method does not rely on the specific frequency or time characteristics of the interference signal, but performs cancellation based on information such as the actual waveform and phase of the interference signal. Therefore, the types of interference signals suppressed by this application are wider. No matter whether it is narrowband interference or broadband interference, as long as the accurate information of the reference interference signal can be obtained, it can be cancelled by adjusting the amplitude equalization operation. It also has a good inhibitory effect on broadband interference signals that are difficult to suppress by traditional anti-interference algorithms.

[0024] The above-mentioned dual-antenna-based agile navigation receiver anti-interference receiving system adopts a dual-antenna-based RF analog cancellation scheme, and the present application adjusts the amplitude and phase characteristics of the interference signal received on the reference antenna according to the correlation between the received signals of different antennas, eliminates the interference signal superimposed on the receiving antenna, and achieves the anti-interference purpose. The antenna installation position is not restricted, and there is no need to have strict restrictions on the installation position of the sub-antenna like the anti-interference antenna array, so it is more versatile; and the cost of the components used in the hardware solution of the set RF interference cancellation module is relatively low, which can effectively control the cost; the analog cancellation scheme is adopted, and the types of interference signals suppressed are wider, not limited to specific interference types, and it also has a better suppression effect on broadband interference signals that are difficult to suppress with traditional anti-interference algorithms, and can realize anti-interference of agile unmanned aerial vehicle navigation.

[0025] In one embodiment, the radio frequency interference cancellation module includes a digitally controlled attenuator, a power divider and phase shifter, an IQ vector modulator, a microcontroller, a power measurement module, a combiner, and a splitter.

[0026] In one embodiment, the radio frequency interference cancellation module is configured to perform amplitude adjustment and phase adjustment on the reference interference signal, including:

[0027] The reference interference signal S1 is input into the RF interference cancellation module and passes through the digital controlled attenuator. After attenuation, it is recorded as , then enters the power divider phase shifter, outputs two orthogonal signals to the IQ vector modulator, and the IQ vector modulator adjusts the phase of the reference interference signal to obtain , where A represents the amplitude and θ represents the phase.

[0028] In one embodiment, performing interference cancellation based on the reference interference signal after amplitude and phase adjustment and the signal received by the receiving antenna includes:

[0029] The amplitude- and phase-adjusted signal is combined with the signal S0 received by the receiving antenna to obtain S2, which is then output to the power measurement module for power estimation. The microcontroller reads the power estimation result and adjusts the amplitude and phase of the reference interference signal to cancel the interference between the reference interference signal and the interference signal received by the receiving antenna.

[0030] In one embodiment, Figure 2 and Figure 3 As shown in FIG, the interference cancellation process includes:

[0031] Initialize the phase adjustment step, amplitude adjustment step, phase search times, and amplitude search times;

[0032] The phase of the reference interference signal is adjusted in steps, and the power of the combined signal after each phase adjustment is obtained through the power measurement chip;

[0033] After the phase search is completed, the minimum power value is searched and the corresponding optimal phase value is obtained; at the optimal phase value, the attenuation of the digital controlled attenuator is adjusted to perform amplitude adjustment;

[0034] The attenuation is adjusted sequentially, and the power of the combined signal after each amplitude adjustment is obtained from the power measurement module. After the amplitude search is completed, the minimum power extreme value is searched and the corresponding optimal amplitude is obtained.

[0035] The optimal phase and amplitude are output to the digitally controlled attenuator and IQ vector modulator to complete the interference cancellation process.

[0036] In one embodiment, the system also includes a power evaluation module; the power evaluation module is used to perform power evaluation on the navigation signal after interference cancellation, and use the power evaluation result to reset the phase adjustment step, amplitude adjustment step, phase search times and amplitude search times to perform interference cancellation.

[0037] In one embodiment, the power evaluation module is further configured to perform power evaluation on the navigation signal after interference cancellation, and the process includes:

[0038] ;

[0039] Where ICR stands for Interference Cancellation Ratio, in dB. represents the received signal power before cancellation, The signal power after cancellation is Represents the receiving channel signal, represents the signal after cancellation, and N is the data length.

[0040] In a specific embodiment, Figure 4 and Figure 5 As shown in FIG, it is a comparison diagram before and after cancellation of broadband interference with a bandwidth of 10 MHz. It can be seen that the technical solution effectively suppresses the broadband interference signal, verifying the effectiveness of the technical solution.

[0041] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0042] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and such modifications and improvements are intended to fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A dual-antenna-based smart navigation receiver anti-interference receiving system, characterized in that: The system includes a receiving antenna installed in the sky direction and a reference antenna in the ground direction, as well as a radio frequency interference cancellation module and a navigation receiving module; The receiving antenna is used to receive the navigation signal; the reference antenna is used to receive the reference interference signal; The radio frequency interference cancellation module is used to adjust the amplitude and phase of the reference interference signal, and perform interference cancellation on the reference interference signal after amplitude and phase adjustment with the signal received by the receiving antenna to obtain a navigation signal after interference cancellation; The navigation receiving module is used to perform navigation signal reception processing on the navigation signal after interference cancellation; Interference cancellation is performed based on the reference interference signal after amplitude and phase adjustment and the signal received by the receiving antenna, including: The amplitude- and phase-adjusted signal is combined with the signal S0 received by the receiving antenna to obtain S2, which is then output to the power measurement module for power estimation. The microcontroller reads the power estimation result and adjusts the amplitude and phase of the reference interference signal to cancel the interference between the reference interference signal and the interference signal received by the receiving antenna. The interference cancellation process includes: Initialize the phase adjustment step, amplitude adjustment step, phase search times, and amplitude search times; The phase of the reference interference signal is adjusted in steps, and the power of the combined signal after each phase adjustment is obtained through the power measurement chip; After the phase search is completed, the minimum power value is searched and the corresponding optimal phase value is obtained; at the optimal phase value, the attenuation of the digital controlled attenuator is adjusted to perform amplitude adjustment; The attenuation is adjusted sequentially, and the power of the combined signal after each amplitude adjustment is obtained from the power measurement module. After the amplitude search is completed, the minimum power extreme value is searched and the corresponding optimal amplitude is obtained. The optimal phase and amplitude are output to the digitally controlled attenuator and IQ vector modulator to complete the interference cancellation process.

2. The system according to claim 1, wherein: The radio frequency interference cancellation module includes a digitally controlled attenuator, a power divider and phase shifter, an IQ vector modulator, a microcontroller, a power measurement module, a combiner and a splitter.

3. The system according to claim 2, characterized in that The radio frequency interference cancellation module is used to perform amplitude adjustment and phase adjustment on the reference interference signal, including: The reference interference signal S1 is input into the radio frequency interference cancellation module and passes through the digital controlled attenuator. After attenuation, it is recorded as , then enters the power divider phase shifter, outputs two orthogonal signals to the IQ vector modulator, and the IQ vector modulator adjusts the phase of the reference interference signal to obtain , where A represents the amplitude and θ represents the phase.

4. The system according to claim 1, wherein: The system also includes a power evaluation module; the power evaluation module is used to perform power evaluation on the navigation signal after interference cancellation, and use the power evaluation result to reset the phase adjustment step, amplitude adjustment step, phase search times and amplitude search times to perform interference cancellation.

5. The system according to claim 4, characterized in that The power evaluation module is further configured to perform power evaluation on the navigation signal after interference cancellation, and the process includes: Where ICR stands for Interference Cancellation Ratio, in dB. represents the received signal power before cancellation, The signal power after cancellation is Represents the receiving channel signal, represents the signal after cancellation, and N is the data length.

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