Digital frequency band protection method for integrated radio frequency system

Abstract

The invention discloses a digital frequency band protection method for an integrated radio frequency system, belongs to the technical field of integrated radio frequency integration, and is used for performing receiving protection processing and transmitting protection processing on signals in a digital signal processing stage between a broadband radio frequency transceiving subsystem and a signal processing subsystem in the integrated radio frequency system. According to the method, from the aspect of frequency division multiplexing, required signal frequency points are selected through the configurable band-pass filter bank for subsequent processing, and frequency points interfering other load systems are filtered through the configurable band-stop filter bank, so that the frequency band protection function of the integrated radio frequency system is achieved, and guarantee is provided for multi-load cooperative work; meanwhile, through flexible implementation of a field programmable gate array (FPGA) device, the method can multiplex a hardware platform with a broadband radio frequency transceiving subsystem or a signal processing subsystem, and the problem that independent equipment must be adopted in a traditional electromagnetic signal processing method is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated radio frequency integration, and in particular relates to a digital frequency band protection method for an integrated radio frequency system. Background Art

[0002] In order to adapt to the modern combat environment, combat equipment must be equipped with various information systems such as radar, communications, and electronic warfare. The ever-increasing payload equipment leads to too many radio frequency antennas in modern combat scenarios, causing electromagnetic interference and electromagnetic compatibility problems, affecting overall combat effectiveness and survivability.

[0003] From the perspective of radio system implementation, radar and communication are both the process of transmitting and receiving electromagnetic waves, electronic warfare reconnaissance is electromagnetic wave reception, and electronic interference is electromagnetic wave transmission. Broadband integrated RF system technology is an important way to solve the integration and collaborative work of multiple RF functions such as radar, communication, and electronic warfare on combat platforms. In order to avoid mutual interference of electromagnetic signals between different payload functions, time division, frequency division, locking, blanking and other measures can usually be used to achieve compatible work of different functional payloads. For example, in the document "Fan Maoyu. Research on Key Technologies of Reconfigurable Filter Circuits for RF Integrated Integrated Systems [D]. University of Electronic Science and Technology of China, 2021", with the RF integrated integrated system as the application background, the constant bandwidth reconfigurable filter circuit technology and the reflection-free reconfigurable circuit technology were studied. It is implemented using varactor diodes or dedicated chip technology. At this stage, further discussion and in-depth research are needed in terms of processing technology and chip integration design; but this method is relatively costly to implement. In the document "Wu Qi, Wang Xiaoming, Sun Hongtao, et al. Overall design technology of antenna aperture synthesis for advanced aircraft platforms [J]. General Aerospace Technology, 2021, 5(04): 7-13", in order to avoid mutual interference between frequency-using equipment, the overall design technology of antenna aperture synthesis was used as a breakthrough point to solve the electromagnetic interference problem of equipment; however, this method cannot effectively realize the problem of multiplexing of broadband RF transceiver subsystems or signal processing subsystems; in the document "Liu Hongbo, Zhang Yunshuo, Meng Jin, et al. Radio station active interference management method based on interference cancellation [J]. Firepower and Command Control, 2023, 48(01): 65-71+77", an active interference management method based on interference cancellation was designed to solve the active interference problem, but because it is based on co-site interference cancellation technology, it needs to refer to the antenna channel;

[0004] Therefore, in view of the above problems, the present invention proposes a digital frequency band protection method for an integrated radio frequency system based on the above prior art, so as to solve the problems existing in the above prior art. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the deficiencies in the prior art, the present invention provides a digital frequency band protection method for an integrated radio frequency system, which can provide protection for the collaborative work of multiple loads from the perspective of frequency division multiplexing, while avoiding interference from signals in other frequency bands, thereby solving the problems of traditional processing methods that cannot be multiplexed with a broadband radio frequency transceiver subsystem or a signal processing subsystem, and cannot avoid signal interference from other loads.

[0007] (II) Technical solution

[0008] In order to achieve the above-mentioned frequency band protection, the present invention provides the following technical solutions for the purpose of performing receiving protection processing and transmitting protection processing on the signals in the signal processing stage after the broadband RF transceiver subsystem and before the signal processing subsystem of the integrated RF system:

[0009] A digital frequency band protection method for an integrated radio frequency system acts on a signal processing stage after a broadband radio frequency transceiver subsystem and before a signal processing subsystem residing in the integrated radio frequency system, and performs reception protection processing and transmission protection processing on the signal.

[0010] In a preferred embodiment, the process of performing reception protection processing on the signal includes:

[0011] The receiving signal of the broadband RF transceiver subsystem is converted into a digital baseband signal after orthogonal digital down-conversion and enters the receiving protection device;

[0012] The receiving protection device performs multi-frequency bandpass processing on the digital baseband signal according to the receiving bandpass frequency point and the control switch control configuration information, obtains the filtered orthogonal baseband signal, and sends it to the signal processing subsystem.

[0013] In a preferred embodiment, the receiving protection device is stored in an FPGA device, and includes a plurality of bandpass filters connected in parallel. In the receiving protection device, the impulse response relationship of each parallel bandpass filter is a time domain superposition relationship:

[0014]

[0015] Among them, h ML (n) is the impulse response of the bandpass filter after parallel connection, and h1(n), h2(n), h3(n), and h4(n) are the impulse responses of multiple filters used simultaneously.

[0016] In a preferred embodiment, the process of performing transmission protection processing on the signal includes:

[0017] The signal processing subsystem generates an orthogonal baseband transmission signal. The transmission protection device performs multi-frequency band-stop filtering on the digital baseband signal according to the transmission band-stop frequency point and the control switch configuration information, and outputs the filtered orthogonal baseband signal.

[0018] The orthogonal baseband signal is converted into a broadband RF transmission signal after orthogonal digital up-conversion.

[0019] In a preferred embodiment, the transmission protection device is stored in an FPGA device, and includes a plurality of band-stop filters connected in series. In the transmission protection device, the impulse response relationship of each of the band-stop filters connected in series is a time domain convolution relationship:

[0020]

[0021] Among them, h MH (n) is the impulse response of the series-connected band-stop filter, and h1(n), h2(n), h3(n), and h4(n) are the impulse responses of multiple filters used simultaneously.

[0022] In a preferred embodiment, the filter impulse response is:

[0023] h0(n)=h LP (n)·w(n),0≤n≤M

[0024] Wherein, w(n) is the selected window function, w(n)=0.54-0.46cos(2πn / M), 0≤n≤M;

[0025] h LP (n) is the impulse response model of the low-pass filter,

[0026] In a preferred embodiment, the process in which the receiving protection device performs receiving protection processing on the signal and the transmitting protection device performs transmitting protection processing on the signal includes:

[0027] Input sequence of zero-IF orthogonal vector signals Frequency response function h0(n) of the prototype filter, frequency conversion factor ω0;

[0028] Then, multiple bandpass filters are used to perform parallel processing and then superimpose in the time domain. h0(n) and ω0 are processed;

[0029] Finally, the output sequence of the processed zero intermediate frequency orthogonal vector signal is output

[0030] (III) Beneficial effects

[0031] Compared with the prior art, the present invention provides a digital frequency band protection method for an integrated radio frequency system, which has the following beneficial effects:

[0032] 1. This digital frequency band protection method processes the signal processing stage after the broadband RF transceiver subsystem and before the signal processing subsystem in the integrated RF system by using a bandpass filter group with configurable parameters and a bandstop filter group with configurable parameters. When in use, the required signal frequency point is selected by the bandpass filter group for subsequent processing, and the frequency point that interferes with other load systems is filtered out by the bandstop filter group, so as to achieve the frequency band protection function of the integrated RF system, and can provide protection for the collaborative work of multiple loads from the perspective of frequency division multiplexing. At the same time, due to the flexibility of FPGA processing, the hardware platform can be reused with the broadband RF transceiver subsystem or the signal processing subsystem, which solves the problem that the traditional electromagnetic signal processing method cannot be reused with the broadband RF transceiver subsystem or the signal processing subsystem, and avoids signal interference from other loads;

[0033] 2. This method encodes and stores the receiving protection device and the transmitting protection device based on the FPGA device. Since FPGA technology is a general and mature technology, the implementation cost of the receiving protection device and the transmitting protection device is low;

[0034] 3. This method processes electromagnetic signals based on a combination of data processing and signal processing, which can complement each other and effectively ensure the effect of frequency band protection;

[0035] 4. This method is based on RF allocation technology, which minimizes the mutual electromagnetic interference between different loads. It does not require a reference antenna and achieves the purpose of receiving protection processing and transmitting protection processing of multi-band loads in an integrated RF system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of the frequency band protection method of the present invention;

[0037] Figure 2 The design block diagram of the bandpass filter with variable parameters of the present invention;

[0038] Figure 3 The design block diagram of the band-stop filter with variable parameters of the present invention;

[0039] Figure 4 The amplitude-frequency response and zero-pole diagram of the prototype low-pass filter and band-pass filter of Embodiment 2 of the present invention;

[0040] Figure 5 The amplitude-frequency response and zero-pole diagram of the prototype high-pass filter and the band-stop filter of Embodiment 2 of the present invention;

[0041] Figure 6 This is a graph showing the amplitude-frequency characteristics of multiple bandpass and bandstop filters according to Example 2 of the present invention.

[0042] Among them: Figure 4 In the figure, Figure (a) is the amplitude-frequency response diagram of the prototype low-pass filter, Figure (b) is the zero-pole diagram of the prototype low-pass filter, Figure (c) is the amplitude-frequency response diagram of the band-pass filter, and Figure (d) is the zero-pole diagram of the band-pass filter;

[0043] exist Figure 5 In the figure, Figure (a) is the amplitude-frequency response diagram of the prototype high-pass filter, Figure (b) is the zero-pole diagram of the prototype high-pass filter, Figure (c) is the amplitude-frequency response diagram of the band-stop filter, and Figure (d) is the zero-pole diagram of the band-stop filter;

[0044] exist Figure 6 In the figure, Figure (a) is the amplitude-frequency response diagram of the bandpass filter group, and Figure (b) is the amplitude-frequency response diagram of the bandstop filter group. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Example 1: Please refer to Figure 1-Figure 3 , the present invention provides a technical solution:

[0047] A digital frequency band protection method for an integrated radio frequency system is implemented by a system consisting of a plurality of bandpass filter groups with configurable parameters and a plurality of bandstop filter groups with configurable parameters. The operating principle is as follows: in the process of receiving electromagnetic signals, the required signal frequency point can be selected by the bandpass filter group for subsequent processing; in the process of transmitting electromagnetic signals, the frequency point that interferes with other load systems can be filtered out by the bandstop filter group, so as to achieve the frequency band protection function of the integrated radio frequency system. The method realizes multi-frequency point dynamic configurable bandpass / bandstop filtering by using field programmable gate array (FPGA) devices. The method can fully balance the processing power and hardware resource utilization requirements, and meet the utilization and protection needs of specific frequency band resources in integrated radio frequency transceiver processing.

[0048] The design process of the digital frequency band protection method for the integrated radio frequency system of the present invention mainly includes the design of a bandpass filter group, a bandstop filter group and a field programmable gate array (FPGA) device, specifically including

[0049] Step 1: Design a prototype filter

[0050] Step 1.1: Design a low-pass prototype filter

[0051] Compared with IIR (infinite impulse response) filter, FIR (finite impulse response) filter has strict linear phase characteristics and stable response output. In this embodiment, FIR filter is selected as the prototype filter and designed by window function method;

[0052] Step 1.1.1: An ideal low-pass filter allows all frequency components of the signal below the specified cutoff frequency to pass through, while other frequency components cannot pass through; the frequency domain response and impulse response models of the ideal low-pass filter are

[0053]

[0054]

[0055] Step 1.1.2: Since the impulse response required to realize an ideal low-pass filter is infinitely long, it is impossible to design an ideal FIR low-pass filter; you can use the windowing method to approximate the ideal impulse response with a finite-length filter:

[0056] h0(n)=h LP (n)·w(n),0≤n≤M

[0057] Wherein, w(n) is a selected window function; this embodiment selects the Hamming window in the generalized cosine window as the window function, as follows:

[0058] w(n)=0.54-0.46cos(2πn / M),0≤n≤M

[0059] Step 1.2: Design a high-pass prototype filter

[0060] For the high-pass filter, the prototype filter design method is similar to the low-pass prototype filter, and its impulse response is:

[0061]

[0062] The rest of the derivation is the same as for the low-pass filter;

[0063] Step 2: Frequency transform the prototype filter designed in step 1

[0064] Step 2.1: Frequency transform the low-pass prototype filter

[0065] The low-pass filter is a filter centered on zero frequency, and can be converted into a band-pass filter centered on any normalized frequency point by frequency conversion;

[0066] Step 2.1.1: Convert the FIR filter into the z domain for representation. Its transfer function is H0(z) which can be expressed as:

[0067] H0(z)=∑b n z n , 0≤n≤M

[0068] Where b is the M-order filter coefficient;

[0069] Its frequency characteristic function is:

[0070]

[0071] Where ω is the normalized frequency;

[0072] Step 2.1.2: Perform frequency transformation on this filter, ω0 is the normalized frequency point to be transformed, and the frequency characteristics of the transfer function after frequency transformation are obtained:

[0073]

[0074] By choosing different ω0, we can get bandpass digital filters with different characteristics.

[0075] At the same time, the impulse response after frequency conversion can also be obtained:

[0076]

[0077] It can be seen that the impulse response of the filter after frequency transformation is a complex filter;

[0078] Step 2.2: Frequency transform the high-pass prototype filter

[0079] The frequency conversion method of the high-pass filter is the same as the frequency conversion method of the low-pass prototype filter described in step 2.1;

[0080] Step 3: Merge the filters after the frequency conversion in step 2 to realize the use of multiple filters. Multiple filters can be used at the same time, taking four filters as an example;

[0081] Multiple bandpass filters are processed in parallel, and their filter impulse responses are superimposed in the time domain:

[0082]

[0083] Multiple band-stop filters are processed serially, and their filter impulse responses are related by time-domain convolution:

[0084]

[0085] h1(n), h2(n), h3(n), and h4(n) are impulse responses of multiple filters used simultaneously;

[0086] Step 4: Configure the combined filter using a field programmable gate array (FPGA)

[0087] Field Programmable Gate Array (FPGA) has the advantages of general flexibility, parallel efficiency, low latency and low power consumption, and has become an essential processing chip for RF transceiver systems, signal processing subsystems, and other integrated RF systems, as well as a basic supporting technology;

[0088] The variable parameter filter provided in this embodiment is designed and implemented by FPGA technology; the variable parameter filter can be called and instantiated multiple times in the implementation to form a situation where multiple filters can be used simultaneously;

[0089] Step 4.1: Design a bandpass filter with variable parameters. The design block diagram is as follows: Figure 2 As shown;

[0090] exist Figure 2 middle, is the input sequence, which is a zero intermediate frequency orthogonal vector signal; is the output sequence, which is also a zero intermediate frequency orthogonal vector signal; h0(n) is the frequency response function of the windowed prototype filter, which is preset before use and stored in the random access memory (RAM) of the FPGA when used; ω0 is the frequency conversion factor, which can be achieved by a phase accumulator; multiple bandpass filters are superimposed in the time domain after parallel processing;

[0091] Step 4.2: Similarly, the design method for the band-stop filter is the same as the method for designing a variable parameter bandpass filter in step 4.1; the design block diagram of the variable parameter band-stop filter is as follows Figure 3 As shown; multiple bandpass filters are processed in series.

[0092] When using, Figure 1 As shown, the above method described in this embodiment is used in the signal processing stage residing after the broadband RF transceiver subsystem and before the signal processing subsystem; due to the flexibility of FPGA processing, the hardware platform can be reused with the broadband RF transceiver subsystem or the signal processing subsystem.

[0093] The typical application process of the above method is as follows:

[0094] (1) For the signal receiving and processing process, the receiving signal of the broadband RF transceiver subsystem is converted into a digital baseband signal after orthogonal digital down-conversion and enters the receiving protection device;

[0095] The receiving protection device can perform multi-frequency passband processing on the digital baseband signal according to the receiving passband frequency point and the control switch control configuration information to avoid interference from signals in other frequency bands;

[0096] (2) For the signal transmission processing process, the baseband transmission signal generated by the signal processing subsystem is typically an active interference signal. The transmission protection device can perform multi-frequency band-stop processing on the digital baseband signal according to the configuration information such as the transmission band-stop frequency and the control switch to avoid interference with the signals of other loads and output the filtered orthogonal baseband signal;

[0097] Then, after orthogonal digital up-conversion, it is converted into a radio frequency transmission signal.

[0098] Example 2: Please refer to Figure 4-Figure 6 , the filter is designed and verified using the method described in Example 1

[0099] The bandpass filter designed based on the window function and frequency conversion method is implemented and verified in this embodiment with the following indicators:

[0100] (1) Filter order M = 64;

[0101] (2) Assume that the cutoff frequency of any low-pass prototype filter is ω c =3 / 60πrad / sample as an example;

[0102] (3) Assume a bandpass filter with arbitrary frequency conversion point, taking ω0 = 5 / 60πrad / sample as an example;

[0103] (4) Design the filter to have a stopband suppression of no less than 50db;

[0104] By this method, a 64-order complex bandpass filter is obtained, and its cutoff frequency for the prototype filter is ω c , the center frequency of the bandpass frequency is ω0; the amplitude-frequency response and zero-pole diagram of the prototype filter and bandpass filter are as follows Figure 4 As shown in the figure, the equivalent cut-off frequency and center frequency of the designed filter can be parameterized by frequency allocation.

[0105] Similarly, the band-stop filter can be designed using the window function and frequency conversion method. This embodiment is implemented and verified with similar indicators; the amplitude-frequency response and zero-pole diagram of the prototype filter and the bandpass filter are shown in Figure 5 shown.

[0106] When multiple filters can be used at the same time; multiple bandpass filters are processed in parallel, and their filter impulse responses are in the relationship of time domain superposition; multiple bandstop filters are processed in series, and their filter impulse responses are in the relationship of time domain convolution; in this embodiment, multiple filters can be set with different parameters, taking the simultaneous use of four filters as an example:

[0107] (1) Assume the prototype filter cutoff frequency,

[0108] (2) Set the frequency conversion point

[0109] The amplitude-frequency characteristics of its bandpass and bandstop filters are as follows: Figure 6 shown.

[0110] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0111] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A digital frequency band protection method for an integrated radio frequency system, characterized in that: The method is used in a signal processing stage residing after a broadband radio frequency transceiver subsystem and before a signal processing subsystem of an integrated radio frequency system, and performs reception protection processing and transmission protection processing on a signal.

2. A digital frequency band protection method for an integrated radio frequency system as claimed in claim 1, characterized in that: The process of receiving and protecting the signal includes: Step 1: The receiving signal of the broadband RF transceiver subsystem is converted into a digital baseband signal after orthogonal digital down-conversion and enters the receiving protection device; Step 2: The receiving protection device performs multi-frequency passband processing on the digital baseband signal according to the receiving passband frequency point and the control switch control configuration information, obtains the filtered orthogonal baseband signal, and sends it to the signal processing subsystem.

3. A digital frequency band protection method for an integrated radio frequency system as claimed in claim 2, characterized in that: The receiving protection device is stored in the FPGA device, and includes a plurality of bandpass filters connected in parallel. In the receiving protection device, the impulse response relationship of each parallel bandpass filter is a time domain superposition relationship: Among them, h ML (n) is the impulse response of the bandpass filter after parallel connection, and h1(n), h2(n), h3(n), and h4(n) are the impulse responses of multiple filters used simultaneously.

4. A digital frequency band protection method for an integrated radio frequency system as claimed in claim 1, characterized in that: The process of transmitting protection processing of the signal includes: Step 1: The signal processing subsystem generates an orthogonal baseband transmission signal, and the transmission protection device performs multi-frequency band-stop filtering on the digital baseband signal according to the transmission band-stop frequency point and the control switch configuration information, and outputs the filtered orthogonal baseband signal; Step 2: The orthogonal baseband signal is converted into a broadband RF transmission signal after orthogonal digital up-conversion.

5. A digital frequency band protection method for an integrated radio frequency system as claimed in claim 4, characterized in that: The transmission protection device is stored in the FPGA device, and includes a plurality of band-stop filters connected in series. In the transmission protection device, the impulse response relationship of each series-connected band-stop filter is a time domain convolution relationship: Among them, h MH (n) is the impulse response of the series-connected band-stop filter, and h1(n), h2(n), h3(n), and h4(n) are the impulse responses of multiple filters used simultaneously.

6. A digital frequency band protection method for an integrated radio frequency system as claimed in claim 3 or 5, characterized in that: The filter impulse response is: <h2 style=";text-align:left;direction:ltr">h0(n) = h<h2 style=";text-align:left;direction:ltr"> LP <h2 style=";text-align:left;direction:ltr"> (n)·w(n),0≤n≤M Wherein, w(n) is the selected window function, w(n)=0.54-0.46cos(2πn / M), 0≤n≤M; h LP (n) is the impulse response model of the low-pass filter, 7. A digital frequency band protection method for an integrated radio frequency system as claimed in claim 2 or 4, characterized in that: The process of the receiving protection device performing receiving protection processing on the signal and the transmitting protection device performing transmitting protection processing on the signal both includes: Input sequence of zero-IF orthogonal vector signals Frequency response function h0(n) of the prototype filter, frequency conversion factor ω0; Then, multiple bandpass filters are used to perform parallel processing and then superimpose in the time domain. h0(n) and ω0 are processed; Finally, the output sequence of the processed zero intermediate frequency orthogonal vector signal is output

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