Reconfigurable digital beam forming method and system based on broadband radio frequency direct acquisition array

Abstract

The invention discloses a reconfigurable digital beam forming method and system based on a broadband radio frequency direct acquisition array, belongs to the technical field of electronic information, and solves the problem that the beam, bandwidth and polarization are difficult to adjust when a large-scale antenna array is constructed by the existing broadband radio frequency direct acquisition array. According to the invention, the DBF system is used as the sub-array processing units, the broadband DBF system of a large-scale antenna array can be realized by connecting the plurality of sub-array processing units in series or in parallel, and the DBF system can flexibly adjust the system bandwidth, control the number of beams and select a polarization mode on the premise that the beam bandwidth product is not changed. The problem of flexible reconfiguration of wave beams, bandwidth and polarization of a large-scale antenna array is solved, and the method is not limited by an array structure, can be used for a narrowband digital array, can also be used for a broadband digital array, and is not limited by the array structure.

Description

Technical Field

[0001] The present invention belongs to the field of electronic information technology, and relates to a reconfigurable digital beamforming method and system based on a broadband radio frequency direct sampling array. Background Art

[0002] With the continuous progress of digital signal processing technology and the continuous improvement of corresponding processing capabilities, digital arrays, with their characteristics of multiple scanning beams and high design flexibility, have gradually replaced analog array antennas and become the main research direction in the fields of electronic information technology such as communication, countermeasure, and radar. Digital arrays usually use superheterodyne intermediate frequency sampling receivers (including multi-stage analog down-conversion and filtering, A / D intermediate frequency sampling, and digital down-conversion, etc.) to convert the received radio frequency analog signals of each array antenna into baseband digital signals and perform signal processing in the digital domain. Typical signal processing technologies include digital beamforming (DBF) and direction of arrival estimation and other technologies.

[0003] The superheterodyne intermediate frequency sampling receiver is currently the most mature receiver and has been widely used in digital array reception. This receiver has a complex hardware circuit and requires a high-performance band-pass filter to obtain excellent broadband reception performance, resulting in disadvantages such as increased cost, large hardware volume and power consumption, low integration, and poor channel frequency response characteristics, seriously restricting its further application and development in the field of electronic information. Compared with the superheterodyne receiver, the radio frequency direct sampling receiver has attracted wide attention and research due to its simple circuit structure, low power consumption, excellent channel frequency response characteristics, easy integration, small volume, low cost, and easy broadband sampling. Therefore, the broadband radio frequency direct sampling array has broad application prospects in the fields of high-speed measurement and control data transmission, broadband satellite communication, broadband radar detection, etc.

[0004] In actual engineering, due to the limitation of the current FPGA device level and considering the implementation cost and resource consumption, the array scale of the current broadband radio frequency direct sampling array DBF system is usually small. The array consists of several to dozens of array elements, and the number of beams and system bandwidth are relatively fixed, and it can no longer meet the technical requirements of large-scale antenna arrays, adjustable system bandwidth, controllable number of beams, and selectable polarization modes in the fields of high-speed data transmission, broadband satellite communication, broadband radar detection, etc. Compared with the DBF system based on general FPGA, the broadband radio frequency direct sampling array DBF system based on a customized SOC chip has become the mainstream development direction of current engineering applications due to its high working clock rate, high resource utilization rate, low power consumption, low cost, and integrated design of radio frequency sampling and DBF.

[0005] To give full play to the advantages of customized SOC chips, it is necessary to find a flexible and reconfigurable DBF system for broadband RF direct sampling arrays. This system can be used as a sub-array processing unit. By cascading or paralleling multiple sub-array processing units, conventional or adaptive broadband DBF for large-scale antenna arrays can be achieved. Moreover, on the premise of keeping the beam bandwidth product unchanged, the system bandwidth can be flexibly adjusted, the number of beams can be controlled, and the polarization mode can be selected to solve the flexible reconfiguration problems of beams, bandwidth, and polarization for large-scale antenna arrays. Summary of the Invention

[0006] The technical solution of the present invention is used to solve the problem that it is difficult to adjust beams, bandwidth, and polarization when constructing a large-scale antenna array with an existing broadband RF direct sampling array.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] A reconfigurable digital beamforming method based on a broadband RF direct sampling array includes the following steps:

[0009] Step 1: The horizontal and vertical polarization array antennas receive RF signals. After low-noise amplification and preselection filtering, the horizontal and vertical polarization RF signals input to the analog-to-digital converter are obtained.

[0010] Step 2: The horizontal and vertical polarization RF signals are processed by an analog-to-digital converter, a channel time delay device, and digital downconversion to obtain the horizontal and vertical polarization baseband digital signals of each channel.

[0011] Step 3: The horizontal and vertical polarization baseband digital signals of each channel are processed by channel equalization to obtain the horizontal and vertical polarization equalized output signals of each channel.

[0012] Step 4: The horizontal and vertical polarization equalized output signals of each channel are replicated at a high-speed processing clock.

[0013] Step 5: The horizontal and vertical polarization output signals of each replicated channel are polarization synthesized to obtain the left-handed and right-handed polarization output signals of each replicated channel.

[0014] Step 6: The left-handed and right-handed polarization output signals of each replicated channel are respectively subjected to time-domain multi-beam synthesis to obtain the left-handed and right-handed polarization output signals of each preset beam.

[0015] Step 7: According to the cascading or paralleling requirements, the left-handed and right-handed polarization output signals of each preset beam are subjected to cascading summation operation with the upper-level beam output signals to obtain the baseband digital signals of the left-handed and right-handed polarization multi-beam outputs.

[0016] Further, step 1 is specifically as follows:

[0017] The digital array includes a total of M horizontally polarized antennas and M vertically polarized antennas. The radio frequency signal received by the k-th horizontally polarized antenna is , and the radio frequency signal received by the k-th vertically polarized antenna is After passing through the low-noise amplifier and preselection filter, the ADC input radio frequency signal of the k-th horizontally polarized receiving channel is The ADC input radio frequency signal of the k-th vertically polarized receiving channel is

[0018] Furthermore, the specific steps of step 2 are as follows:

[0019] If the sampling frequency of the ADC is F S , the radio frequency signal of the horizontally polarized channel and the radio frequency signal of the vertically polarized channel After being sampled by the ADC, processed by the channel time delay device and DDC, M-channel baseband digital signals of the horizontally polarized channels and M-channel baseband digital signals of the vertically polarized channels can be obtained. Among them, the sampling frequency of the baseband digital signal is F DS , satisfying D = F S / F DS is a positive integer;

[0020] The step 2 further includes the following steps:

[0021] Step 21: Use the sampling frequency F S to directly sample the radio frequency signal of the k-th horizontally polarized channel and the radio frequency signal of the k-th vertically polarized channel , and the radio frequency digital signal of the k-th horizontally polarized channel and the radio frequency digital signal of the k-th vertically polarized channel can be obtained. Where t represents continuous time, which is the time variable of the radio frequency signal, and m represents discrete time index, which is the sampling point after radio frequency sampling;

[0022] Step 22: According to the previously measured delay error of the k-th horizontally polarized channel and the delay error of the k-th vertically polarized channel then the output signal of the channel delay device of the k-th horizontally polarized channel is:

[0023]

[0024] The output signal of the channel delay device of the k-th vertically polarized channel is:

[0025]

[0026] Among them, represents the time delay error of the k-th horizontal polarization channel The corresponding integer sampling value, is the time delay error of the k-th vertical polarization channel The corresponding integer sampling value can be represented by the following logic and

[0027]

[0028]

[0029] Among them, round(·) represents the rounding operation;

[0030] Step 23: Calculate the digital mixing angular frequency ω of digital down-conversion according to the operating frequency band, ADC sampling frequency, and baseband digital signal sampling frequency RF , the integer decimation factor D = F S / F DS , design the coefficients h LP (m) of the programmable real low-pass filter according to the system bandwidth requirement, then the DDC output signal s H,k (n) of the k-th horizontal polarization channel is:

[0031]

[0032] The DDC output signal s V,k (n) of the k-th vertical polarization channel is:

[0033]

[0034] Among them, the symbol represents the linear convolution operation.

[0035] Furthermore, the specific content of step 3 is as follows:

[0036] According to the previously measured impulse responses of the equalizers of the M horizontal polarization channels and the impulse responses of the equalizers of the M vertical polarization channels , perform equalization processing on the DDC output signals of the M horizontal polarization channels and the DDC output signals of the M vertical polarization channels, and the equalized output signals

[0037]

[0038] Step 3 also includes the following steps:

[0039] Step 31: According to the equalizer impulse response \(g\) H,k (n) of the \(k\)-th horizontal polarization channel, perform equalization processing on the DDC output signal \(s\) H,k (n) of the \(k\)-th horizontal polarization channel. Then, the equalized output signal \(x\) H,k (n) of the \(k\)-th horizontal polarization channel is:

[0040]

[0041] Step 32: According to the equalizer impulse response \(g\) V,k (n) of the \(k\)-th vertical polarization channel, perform equalization processing on the DDC output signal \(s\) V,k (n) of the \(k\)-th vertical polarization channel. Then, the equalized output signal \(x\) V,k (n) of the \(k\)-th vertical polarization channel is:

[0042]

[0043] Further, the specific content of step 4 is as follows:

[0044] Given the system high-speed processing clock frequency \(F\) CS and the preset number of beams \(B\), where \(B\geq1\). According to the requirement of the actual number of beams \(B\) r \(=\delta\cdot B\), duplicate the equalized output signals of the \(M\) horizontal polarization channels and the equalized output signals of the \(M\) vertical polarization channels to obtain the baseband digital signals of the \(M\) horizontal polarization duplicate channels and the baseband digital signals of the \(M\) vertical polarization duplicate channels

[0045] Step 4 further includes the following steps:

[0046] Step 41: Duplicate the equalized output signal \(x\) H,k (n) of the \(k\)-th horizontal polarization channel. Then, the baseband digital signal of the \(k\)-th horizontal polarization duplicate channel is:

[0047]

[0048] where \(\rho\) represents the duplicate channel count value, and \(S\) represents the maximum number of duplicate channels, satisfying \(S = F\) CS / \(F\) DS , \(\delta\) represents the ratio of the actual number of beams to the preset number of beams, and takes values in the range of \([1, S]\);

[0049] Step 42: Duplicate the equalized output signal \(x\) V,k(n) Perform data replication, then the baseband digital signal of the k-th vertical polarization replication channel is:

[0050]

[0051] Further, the specific steps of step 5 are as follows:

[0052] According to the system polarization mode requirements, preset the two-dimensional polarization synthesis matrix corresponding to M horizontal and vertical polarization replication channels The baseband digital signals of M horizontal polarization replication channels The baseband digital signals of M vertical polarization replication channels are subjected to polarization synthesis to obtain the baseband digital signals of M left-handed polarization replication channels The baseband digital signals of M right-handed polarization replication channels

[0053] Step 5 further includes the following steps:

[0054] Step 51, the ρ-th two-dimensional polarization synthesis matrix in the k-th horizontal and vertical polarization replication channels is:

[0055]

[0056] where are the four elements of the two-dimensional polarization synthesis matrix respectively, and ρ ∈ [0, S - 1];

[0057] Step 52, the baseband digital signal of the k-th horizontal polarization replication channel The baseband digital signal of the k-th vertical polarization replication channel are subjected to polarization synthesis to obtain the baseband digital signal of the k-th left-handed polarization replication channel

[0058]

[0059] Step 53, the baseband digital signal of the k-th horizontal polarization replication channel The baseband digital signal of the k-th vertical polarization replication channel are subjected to polarization synthesis to obtain the baseband digital signal of the k-th right-handed polarization replication channel

[0060]

[0061] Further, the specific steps of step 6 are as follows:

[0062] The baseband digital signals of M left-handed polarization replication channels Baseband digital signal of the M-channel right-handed circular polarization replication channel After performing broadband time-domain multi-beam synthesis respectively, baseband digital signals of B left-handed circular polarization pre-set beams can be obtained Baseband digital signals of B right-handed circular polarization pre-set beams

[0063] Step 6 further includes the following steps:

[0064] Step 61: For the b-th pre-set beam, the ρ-th amplitude addition weighting coefficient in the k-th left-handed circular polarization replication channel is Then the amplitude addition weighted output signal of the k-th left-handed circular polarization replication channel Can be expressed as:

[0065]

[0066] For the b-th pre-set beam, the ρ-th amplitude addition weighting coefficient in the k-th right-handed circular polarization replication channel is Then the amplitude addition weighted output signal of the k-th right-handed circular polarization replication channel Can be expressed as:

[0067]

[0068] Step 62: When performing conventional beam synthesis and the fractional delay filter compensates at the channel level, for the b-th pre-set beam, the real impulse response of the ρ-th fractional delay filter in the k-th left-handed circular polarization replication channel is Then the baseband digital signal of the b-th left-handed circular polarization pre-set beam Can be expressed as:

[0069]

[0070] For the b-th pre-set beam, the real impulse response of the ρ-th fractional delay filter in the k-th right-handed circular polarization replication channel is Then the baseband digital signal of the b-th right-handed circular polarization pre-set beam Can be expressed as:

[0071]

[0072] Step 63: When performing conventional beam synthesis and the fractional delay filter compensates at the sub-array level, for the ρ-th fractional delay filter in the b-th left-handed circular polarization pre-set beam, the real impulse response is Then the baseband digital signal of the b-th left-handed circular polarization pre-set beam Can be expressed as:

[0073]

[0074] The real impulse response of the ρ-th fractional delay filter in the b-th right-handed polarized pre-set beam is Then the baseband digital signal of the b-th right-handed polarized pre-set beam can be expressed as:

[0075]

[0076] Step 64: When performing adaptive beam synthesis and the complex FIR filter compensates at the sub-array level, the impulse response of the ρ-th complex FIR filter in the b-th left-handed polarized pre-set beam is Then the baseband digital signal of the b-th left-handed polarized pre-set beam can be expressed as:

[0077]

[0078] The impulse response of the ρ-th complex FIR filter in the b-th right-handed polarized pre-set beam is Then the baseband digital signal of the b-th right-handed polarized pre-set beam can be expressed as:

[0079]

[0080] Furthermore, step 7 is specifically as follows:

[0081] According to the requirements of system parallel or series connection, the baseband digital signals of the B left-handed polarized pre-set beams at the C-th level of the current system The baseband digital signals of the B right-handed polarized pre-set beams And the series summation output signals of the B left-handed polarized pre-set beams at the (C - 1)-th level The series summation output signals of the B right-handed polarized pre-set beams Perform a series summation operation to obtain the series summation output signals of the B left-handed polarized pre-set beams at the C-th level of the current system The series summation output signals of the B right-handed polarized pre-set beams

[0082] Step 7 further includes the following steps:

[0083] Step 71: According to the requirements of system series connection, when the current unit is at the C = 1 level, the baseband digital signal of the b-th left-handed polarized pre-set beam of the current unit Is directly used as the series summation output signal of the b-th left-handed polarized pre-set beam of the current unit

[0084]

[0085] Step 72: When the current unit is at the C = 1st level according to the system series connection requirement, the baseband digital signal of the b-th right-handed polarized preset beam of the current unit is directly used as the series summation output signal of the b-th right-handed polarized preset beam of the current unit

[0086]

[0087] Step 73: When the current unit is at the C≥2nd level according to the system series connection requirement, the baseband digital signal of the b-th left-handed polarized preset beam of the current unit is subjected to a series summation operation with the series summation output signal of the b-th left-handed polarized preset beam of the previous unit to obtain the series summation output signal of the b-th left-handed polarized preset beam of the current unit

[0088]

[0089] Step 74: When the current unit is at the C≥2nd level according to the system series connection requirement, the baseband digital signal of the b-th right-handed polarized preset beam of the current unit is subjected to a series summation operation with the series summation output signal of the b-th right-handed polarized preset beam of the previous unit to obtain the series summation output signal of the b-th right-handed polarized preset beam of the current unit

[0090]

[0091] Furthermore, step 7 further includes the following steps:

[0092] Step 75: According to the system parallel connection requirement, the baseband digital signal of the b-th left-handed polarized preset beam is directly used as the series summation output signal of the b-th left-handed polarized preset beam

[0093]

[0094] Step 76: According to the system parallel connection requirement, the baseband digital signal of the b-th right-handed polarized preset beam is directly used as the series summation output signal of the b-th right-handed polarized preset beam

[0095]

[0096] A reconfigurable digital beamforming system based on a broadband radio frequency direct sampling array, comprising a radio frequency signal receiving module, a signal frequency conversion processing module, a signal equalization processing module, a signal data replication module, a signal polarization synthesis module, a time-domain multi-beam synthesis module, and a multi-beam output module;

[0097] The radio frequency signal receiving module is used to receive radio frequency signals through horizontal and vertical polarization array antennas, and after low-noise amplification and preselection filtering, obtain the horizontal and vertical polarization radio frequency signals input to the analog-to-digital converter;

[0098] The signal frequency conversion processing module is used to obtain the horizontal and vertical polarization baseband digital signals of each channel after the horizontal and vertical polarization radio frequency signals are processed by an analog-to-digital converter, a channel time delay device, and digital down-conversion;

[0099] The signal equalization processing module is used to perform channel equalization processing on the horizontal and vertical polarization baseband digital signals of each channel to obtain the horizontal and vertical polarization equalized output signals of each channel;

[0100] The signal data replication module is used to replicate the data of the horizontal and vertical polarization equalized output signals of each channel under a high-speed processing clock;

[0101] The signal polarization synthesis module is used to perform polarization synthesis on the horizontal and vertical polarization output signals of each replicated channel to obtain the left-handed and right-handed polarization output signals of each replicated channel;

[0102] The time-domain multi-beam synthesis module is used to perform time-domain multi-beam synthesis on the left-handed and right-handed polarization output signals of each replicated channel respectively to obtain the left-handed and right-handed polarization output signals of each preset beam;

[0103] The multi-beam output module is used to perform a series summation operation on the left-handed and right-handed polarization output signals of each preset beam and the upper-level beam output signals according to the series or parallel requirements to obtain the baseband digital signals of the left-handed and right-handed polarization multi-beam outputs.

[0104] The advantages of the present invention are as follows:

[0105] (1) The DBF system based on the broadband radio frequency direct sampling array provided by the present invention can either use the system as a sub-array processing unit, and by connecting multiple sub-array processing units in series or in parallel, realize the conventional or adaptive broadband DBF of a large-scale antenna array, or flexibly adjust the system bandwidth, control the number of beams, and select the polarization mode on the premise that the beam bandwidth product remains unchanged, so as to solve the flexible reconfiguration problem of the beam, bandwidth, and polarization of a large-scale antenna array.

[0106] (2) The present invention uses the DBF system as a sub-array processing unit. By cascading or paralleling multiple sub-array processing units, a wideband DBF system for a large-scale antenna array can be realized. After the high-speed processing clock frequency F of the DBF system and the preset number of beam B are determined, when S = 1, up to 2B beams can be formed; when S > 1, by using channel data replication, up to 2S·B beams can be formed. The DBF system can flexibly adjust the system bandwidth, control the number of beams, and select the polarization mode on the premise that the beam bandwidth product 2B·F remains unchanged, solve the flexible reconfiguration problems of beams, bandwidth, and polarization of a large-scale antenna array, and is not restricted by the array structure. It can be applied to conventional beam synthesis of channel amplitude-phase weighting and sub-array fractional delay, channel amplitude-phase weighting and sub-array complex FIR filter adaptive beam synthesis, and can be used for both narrowband digital arrays and broadband digital arrays, and is not restricted by the array structure. CS After the high-speed processing clock frequency F of the DBF system and the preset number of beam B are determined, when S = 1, up to 2B beams can be formed; when S > 1, by using channel data replication, up to 2S·B beams can be formed. The DBF system can flexibly adjust the system bandwidth, control the number of beams, and select the polarization mode on the premise that the beam bandwidth product 2B·F remains unchanged. CS Solve the flexible reconfiguration problems of beams, bandwidth, and polarization of a large-scale antenna array, and is not restricted by the array structure. It can be applied to conventional beam synthesis of channel amplitude-phase weighting and sub-array fractional delay, channel amplitude-phase weighting and sub-array complex FIR filter adaptive beam synthesis, and can be used for both narrowband digital arrays and broadband digital arrays, and is not restricted by the array structure. Description of the Drawings

[0107] Figure 1 is a flowchart of a reconfigurable digital beamforming method based on a wideband radio frequency direct sampling array according to Embodiment 1 of the present invention;

[0108] Figure 2 is a system block diagram of a reconfigurable digital beamforming method based on a wideband radio frequency direct sampling array according to Embodiment 1 of the present invention;

[0109] Figure 3 is a system block diagram of a single wideband digital beamforming system according to Embodiment 1 of the present invention;

[0110] Figure 4 is a schematic diagram of time-domain multi-beam synthesis according to Embodiment 1 of the present invention;

[0111] Figure 5 is a system block diagram of a wideband digital beamforming system for a large-scale array according to Embodiment 2 of the present invention;

[0112] Figure 6 is a system block diagram of the C = 1 level sub-array processing unit according to Embodiment 2 of the present invention;

[0113] Figure 7 is a system block diagram of the C = 2 level sub-array processing unit according to Embodiment 2 of the present invention;

[0114] Figure 8 is a schematic diagram of time-domain multi-beam synthesis of the sub-array processing unit according to Embodiment 2 of the present invention;

[0115] Figure 9 is a schematic diagram of time-domain multi-beam synthesis of the sub-array processing unit according to Embodiment 3 of the present invention. Detailed Embodiments

[0116] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0117] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments:

[0118] Embodiment 1

[0119] As Figure 1-4 shown, specifically, a reconfigurable digital beamforming method based on a broadband radio frequency direct sampling array is disclosed. In this embodiment, the broadband radio frequency direct sampling array has a total of M = 32 horizontally polarized antennas and M = 32 vertically polarized antennas, with an operating frequency band of 7.5 GHz to 8.7 GHz. Eight left-handed conventional beams and eight right-handed conventional beams with a bandwidth of 1.2 GHz and a sampling rate of 1.6 GHz are formed simultaneously, which is implemented using a single DBF system provided by the present invention. The system block diagram is as Figure 3 shown, Figure 3 In the time-domain multi-beam synthesis, the conventional beam synthesis of channel amplitude-phase weighting and channel fractional delay is completed using the structure as Figure 4 shown. The beam bandwidth product of this embodiment is 2 * 8 * 1.6 GHz = 25.6 GHz.

[0120] Based on the above technical requirements, the specific implementation steps of this embodiment are as follows:

[0121] Step 1: The digital array includes a total of 32 horizontally polarized antennas and 32 vertically polarized antennas. Then, the radio frequency signal received by the k-th horizontally polarized antenna is The radio frequency signal received by the k-th vertically polarized antenna is k = 1,..., 32. After passing through a low-noise amplifier (LNA) and a preselection filter, the analog-to-digital converter (ADC) input radio frequency signal of the k-th horizontally polarized receiving channel is The analog-to-digital converter (ADC) input radio frequency signal of the k-th vertically polarized receiving channel is

[0122] Step 2: If the sampling frequency of the analog-to-digital converter (ADC) is 9.6 GHz, the radio frequency signals and of the horizontal and vertical polarization channels, after being sampled by the ADC, processed by the channel time delay device and digital down-conversion (DDC), the baseband digital signals Baseband digital signals of 32 vertically polarized channels Among them, the sampling frequency of the baseband digital signal is 1.6 GHz.

[0123] Since the processing flows of the above 32 horizontal or vertical polarization are the same, in this embodiment, taking the k-th horizontal and vertical polarization receiving channels as an example, step 2 specifically includes the following steps:

[0124] Step 21: Use the sampling frequency of 9.6 GHz to sample the radio frequency signals of the k-th horizontal polarization channel and the radio frequency signals of the k-th horizontal polarization channel for direct radio frequency sampling, and the radio frequency digital signals of the k-th horizontal polarization channel and the radio frequency digital signals of the k-th vertical polarization channel can be obtained. Where t represents continuous time, which is the time variable of the radio frequency signal, and m represents discrete time index, which is the sampling point after radio frequency sampling.

[0125] Step 22: According to the delay error of the k-th horizontal polarization channel measured in advance and the delay error of the k-th vertical polarization channel then the output signal of the channel delay device of the k-th horizontal polarization channel is:

[0126]

[0127] The output signal of the channel delay device of the k-th vertical polarization channel is:

[0128]

[0129] Among them, represents the integer sampling value corresponding to the delay error of the k-th horizontal polarization channel , is the integer sampling value corresponding to the delay error of the k-th vertical polarization channel , which can be represented by the following logic and

[0130]

[0131]

[0132] Among them, round(·) represents the rounding operation.

[0133] Step 23: Calculate the digital mixing angular frequency ω of digital down conversion (DDC) according to the working frequency band, ADC sampling frequency, and baseband digital signal sampling frequency RFIt is -2π×1.5 / 9.6, and the integer decimation multiple is 6. According to the system bandwidth requirement, the coefficients h of a real low-pass filter with a bandwidth of 600 MHz and an order of 63 are designed. LP The DDC output signal s H,k (n) of the k-th horizontal polarization channel is:

[0134]

[0135] The DDC output signal s V,k (n) of the k-th vertical polarization channel is:

[0136]

[0137] Among them, the symbol represents the linear convolution operation.

[0138] Step 3: According to the previously measured impulse responses of the equalizers of the 32 horizontal polarization channels and the impulse responses of the equalizers of the 32 vertical polarization channels perform equalization processing on the DDC output signals of the 32 horizontal polarization channels and the DDC output signals of the 32 vertical polarization channels, and the equalized output signals of the 32 horizontal polarization channels and the equalized output signals of the 32 vertical polarization channels can be obtained. Since the equalization processing methods for each channel are the same,

[0139] Since the equalization processing methods for each channel are the same, in this embodiment, the k-th channel is taken as an example for illustration. Step 3 specifically includes the following steps:

[0140] Step 31: According to the impulse response g H,k (n) of the equalizer of the k-th horizontal polarization channel, perform equalization processing on the DDC output signal s H,k (n) of the k-th horizontal polarization channel. Then, the equalized output signal x H,k (n) of the k-th horizontal polarization channel is:

[0141]

[0142] Step 32: According to the impulse response g V,k (n) of the equalizer of the k-th vertical polarization channel, perform equalization processing on the DDC output signal s V,k (n) of the k-th vertical polarization channel. Then, the equalized output signal x V,k (n) of the k-th vertical polarization channel is:

[0143]

[0144] Step 4: Given that the system high-speed processing clock frequency is 1.6 GHz and the number of preset beams is 8, for the equalized output signals of 32 horizontal polarization channels and the equalized output signals of 32 vertical polarization channels perform data replication to obtain the baseband digital signals of 32 horizontal polarization replicated channels and the baseband digital signals of 32 vertical polarization replicated channels

[0145] Since the data replication method for each channel is the same, this embodiment takes the k-th channel as an example for illustration. The specific steps of Step 4 are as follows:

[0146] Step 41: Perform data replication on the equalized output signal x H,k (n) of the k-th horizontal polarization channel. Then, the baseband digital signal of the k-th horizontal polarization replicated channel is:

[0147]

[0148] Step 42: Perform data replication on the equalized output signal x V,k (n) of the k-th vertical polarization channel. Then, the baseband digital signal of the k-th vertical polarization replicated channel is:

[0149]

[0150] Step 5: According to the system polarization mode requirements, preset the two-dimensional polarization synthesis matrix corresponding to 32 horizontal and vertical polarization replicated channels to perform polarization synthesis on the baseband digital signals of 32 horizontal polarization replicated channels and the baseband digital signals of 32 vertical polarization replicated channels to obtain the baseband digital signals of 32 left-handed polarization replicated channels and the baseband digital signals of 32 right-handed polarization replicated channels

[0151] Since the polarization synthesis method for each replicated channel is the same, this embodiment takes the k-th channel as an example for illustration. The specific steps of Step 5 are as follows:

[0152] Step 51: The 0-th two-dimensional polarization synthesis matrix in the k-th horizontal and vertical polarization replicated channels is:

[0153]

[0154] Step 52: The baseband digital signal of the k-th horizontal polarization replicated channel The baseband digital signal of the k-th vertically polarized replication channel By performing polarization synthesis, the baseband digital signal of the k-th left-handed polarized replication channel can be obtained It is:

[0155]

[0156] Step 53: The baseband digital signal of the k-th horizontally polarized replication channel The baseband digital signal of the k-th vertically polarized replication channel By performing polarization synthesis, the baseband digital signal of the k-th right-handed polarized replication channel can be obtained It is:

[0157]

[0158] Step 6: The baseband digital signals of 32 left-handed polarized replication channels The baseband digital signals of 32 right-handed polarized replication channels Perform broadband time-domain multi-beam synthesis respectively, and the baseband digital signals of 8 left-handed polarized pre-set beams can be obtained The baseband digital signals of 8 right-handed polarized pre-set beams

[0159] Since the broadband time-domain beam synthesis methods of 32 left-handed and right-handed polarized replication channels are the same, this embodiment takes the b-th pre-set beam as an example for illustration. The specific steps of step 6 are as follows:

[0160] Step 61: For the b-th pre-set beam, the amplitude-phase weighting coefficient in the k-th left-handed polarized replication channel is Then the amplitude-phase weighted output signal of the k-th left-handed polarized replication channel Can be expressed as:

[0161]

[0162] For the b-th pre-set beam, the ρ-th amplitude-phase weighting coefficient in the k-th right-handed polarized replication channel is Then the amplitude-phase weighted output signal of the k-th right-handed polarized replication channel Can be expressed as:

[0163]

[0164] Step 62: When performing conventional beam synthesis and compensating at the channel level by the fractional delay filter, for the b-th pre-set beam, the real impulse response of the fractional delay filter in the k-th left-handed polarized replication channel is Then the baseband digital signal of the b-th left-handed polarized pre-set beam Can be expressed as:

[0165]

[0166] For the b-th pre-set beam, the real impulse response of the fractional delay filter in the k-th right-handed circular polarization replication channel is Then the baseband digital signal of the b-th right-handed circular polarization pre-set beam can be expressed as:

[0167]

[0168] where the symbol represents the linear convolution operation.

[0169] Step 7: According to the system parallel connection requirement, the baseband digital signals of 8 left-handed circular polarization pre-set beams and the baseband digital signals of 8 right-handed circular polarization pre-set beams can be directly used as the series summation output signals of 8 left-handed circular polarization pre-set beams and the parallel summation output signals of 8 right-handed circular polarization pre-set beams

[0170] Since the parallel summation method for each pre-set beam is the same, this embodiment takes the b-th pre-set beam as an example for illustration. Step 7 specifically includes the following steps:

[0171] Step 71: According to the system parallel connection requirement, the baseband digital signal of the b-th left-handed circular polarization pre-set beam is directly used as the series summation output signal of the b-th left-handed circular polarization pre-set beam

[0172]

[0173] Step 72: According to the system parallel connection requirement, the baseband digital signal of the b-th right-handed circular polarization pre-set beam is directly used as the series summation output signal of the b-th right-handed circular polarization pre-set beam

[0174]

[0175] Embodiment 2

[0176] As Figure 5-8 shown, in this embodiment, the wideband radio frequency direct sampling array has M = 1024 horizontally polarized antennas and M = 1024 vertically polarized antennas, and the operating frequency band is 7.5 GHz to 8.7 GHz. At the same time, 64 right-handed conventional beams with a bandwidth of 300 MHz and a sampling rate of 400 MHz are formed; the same as Embodiment 1, the beam bandwidth product in this embodiment is 64 * 400 MHz = 25.6 GHz.

[0177] In this embodiment, first, the DBF system provided in this embodiment is used as a sub-array processing unit to simultaneously process 32 horizontally polarized antennas and 32 vertically polarized antennas, and simultaneously form 64 right-handed beams with a bandwidth of 300 MHz and a sampling rate of 400 MHz. Then, 32 sub-array processing units are connected in series in groups of 2 and in parallel in groups of 16 to construct a broadband DBF system for a large-scale array, as Figure 5 shown Figure 5 in which two-stage sub-array processing units are cascaded to form a double-sub-array series structure, and 16 double-sub-array series structures and sub-array beam summation together form a broadband DBF system for a large-scale array.

[0178] Figure 6 and Figure 7 respectively give the system block diagrams of the sub-array processing units at the C = 1 and C = 2 levels in a single double-sub-array series structure. Figure 7 The series summation output in and is respectively Figure 5 corresponding to the preset beam signals output by the double-sub-array series structure in and where the positive integer superscript u takes values between 1 and 16, representing the index of the double-sub-array series structure. Figure 6 and Figure 7 in which the time-domain multi-beam synthesis is completed by using the structure shown in Figure 8 for conventional beam synthesis of channel amplitude addition weighting and sub-array fractional delay.

[0179] Based on the above technical requirements, implementing a single sub-array processing unit according to this embodiment includes the following steps:

[0180] Step 1: The digital array includes a total of 32 horizontally polarized antennas and 32 vertically polarized antennas. Then, the radio frequency signal received by the k-th horizontally polarized antenna is The radio frequency signal received by the k-th vertically polarized antenna is After passing through a low-noise amplifier (LNA) and a preselection filter, the radio frequency signal input to the analog-to-digital converter (ADC) of the k-th horizontally polarized receiving channel is , and the radio frequency signal input to the analog-to-digital converter (ADC) of the k-th vertically polarized receiving channel is

[0181] Step 2: If the sampling frequency of the analog-to-digital converter (ADC) is 9.6 GHz, after the radio frequency signals and of the horizontal and vertical polarization channels are sampled by the ADC, processed by a channel time delay device and digital downconversion (DDC), 32-channel baseband digital signals Baseband digital signals of 32 vertically polarized channels Among them, the sampling frequency of the baseband digital signal is 400 MHz.

[0182] The processing flows of the above 32 horizontally or vertically polarized channels are the same. For the k-th horizontal and vertical polarization receiving channels, step 2 specifically includes the following steps:

[0183] Step 21: Use a sampling frequency of 9.6 GHz for the RF signal of the k-th horizontally polarized channel and the RF signal of the k-th horizontally polarized channel Perform RF direct sampling to obtain the RF digital signal of the k-th horizontally polarized channel and the RF digital signal of the k-th vertically polarized channel

[0184] Step 22: According to the previously measured delay error of the k-th horizontally polarized channel and the delay error of the k-th vertically polarized channel Then the output signal of the channel delay device of the k-th horizontally polarized channel is:

[0185]

[0186] The output signal of the channel delay device of the k-th vertically polarized channel is:

[0187]

[0188] Among them, represents the integer sampling value corresponding to the delay error of the k-th horizontally polarized channel , is the integer sampling value corresponding to the delay error of the k-th vertically polarized channel , which can be represented by the following logic and

[0189]

[0190]

[0191] Among them, the symbol round(·) represents the rounding operation.

[0192] Step 23: Calculate the digital mixing angular frequency of digital down-conversion (DDC) as -2π×1.5 / 9.6, the integer decimation factor as 24, design the coefficients h of a real low-pass filter with a bandwidth of 150 MHz and an order of 63 according to the operating frequency band, ADC sampling frequency, and baseband digital signal sampling frequency LP(m), then the DDC output signal s of the k-th horizontal polarization channel H,k is:

[0193]

[0194] The DDC output signal s of the k-th vertical polarization channel V,k is:

[0195]

[0196] Among them, the symbol represents the linear convolution operation.

[0197] Step 3. According to the equalizer impulse responses previously measured for 32 horizontal polarization channels and the equalizer impulse responses for 32 vertical polarization channels perform equalization processing on the DDC output signals of 32 horizontal polarization channels

[0198]

[0199] Since the equalization processing methods for each channel are the same, for the k-th channel, Step 3 specifically includes the following steps:

[0200] Step 31. According to the equalizer impulse response g H,k (n) of the k-th horizontal polarization channel, perform equalization processing on the DDC output signal s H,k (n) of the k-th horizontal polarization channel. Then, the equalized output signal x H,k (n) of the k-th horizontal polarization channel is:

[0201]

[0202] Among them, the symbol represents the linear convolution operation.

[0203] Step 32. According to the equalizer impulse response g V,k (n) of the k-th vertical polarization channel, perform equalization processing on the DDC output signal s V,k (n) of the k-th vertical polarization channel. Then, the equalized output signal

[0204] x V,k (n) of the k-th vertical polarization channel is:

[0205]

[0206] Among them, the symbol represents the linear convolution operation.

[0207] Step 4: Given the system high-speed processing clock frequency of 1.6 GHz and the preset number of beams of 8, according to the actual number of beams of 32, for the equalized output signals of 32 horizontal polarization channels and the equalized output signals of 32 vertical polarization channels perform data replication to obtain the baseband digital signals of 32 horizontal polarization replication channels and the baseband digital signals of 32 vertical polarization replication channels

[0208] Since the data replication method for each channel is the same, for the k-th channel, Step 4 specifically includes the following steps:

[0209] Step 41: Perform data replication on the equalized output signal x H,k (n) of the k-th horizontal polarization channel, then the baseband digital signal of the k-th horizontal polarization replication channel is:

[0210]

[0211] Among them, ρ represents the replication channel count value, ρ is an integer, S represents the maximum replication channel times, and satisfies S = F CS / F DS , and δ represents the ratio of the actual number of beams to the preset number of beams, and takes values in the interval [1, S].

[0212] Step 42: Perform data replication on the equalized output signal x V,k (n) of the k-th vertical polarization channel, then the baseband digital signal of the k-th vertical polarization replication channel is:

[0213]

[0214] Step 5: According to the requirement that all beams are right-handed polarized, pre-set the two-dimensional polarization synthesis matrix corresponding to M horizontal and vertical polarization replication channels, and the baseband digital signals of 32 horizontal polarization replication channels and the baseband digital signals of 32 vertical polarization replication channels can be polarization synthesized to obtain the baseband digital signals of 32 left-handed polarization replication channels and the baseband digital signals of 32 right-handed polarization replication channels

[0215] Since the polarization synthesis methods for all the replication channels are the same, for the k-th replication channel, Step 5 specifically includes the following steps:

[0216] Step 51. For the ρ (∈[0, 3])-th two-dimensional polarization synthesis matrix in the k-th horizontal and vertical polarization replication channels is:

[0217]

[0218] Step 52. Polarization synthesis is performed on the baseband digital signal of the k-th horizontal polarization replication channel and the baseband digital signal of the k-th vertical polarization replication channel to obtain the baseband digital signal of the k-th left-handed polarization replication channel

[0219]

[0220] Step 53. Polarization synthesis is performed on the baseband digital signal of the k-th horizontal polarization replication channel and the baseband digital signal of the k-th vertical polarization replication channel to obtain the baseband digital signal of the k-th right-handed polarization replication channel

[0221]

[0222] Step 6. Wideband time-domain multi-beam synthesis is respectively performed on the baseband digital signals of the 32 left-handed polarization replication channels and the baseband digital signals of the 32 right-handed polarization replication channels to obtain the baseband digital signals of 8 left-handed polarization pre-set beams and the baseband digital signals of 8 right-handed polarization pre-set beams

[0223] Since the wideband time-domain beam synthesis methods for the 32 left-handed and right-handed polarization replication channels are the same, for the b-th pre-set beam, Step 6 includes the following steps:

[0224] Step 61. For the b-th pre-set beam, the amplitude addition weighting coefficient of the ρ (∈[0, 3])-th in the k-th left-handed polarization replication channel is Then the amplitude addition weighted output signal of the k-th left-handed polarization replication channel

[0225]

[0226] For the b-th pre-set beam, the amplitude addition weighting coefficient of the ρ (∈[0, 3])-th in the k-th right-handed polarization replication channel is Then the amplitude and phase weighted output signal of the k-th right-handed polarization replication channel

[0227]

[0228] where n is an integer.

[0229] Step 62: When performing conventional beamforming and the fractional delay filter compensates at the subarray level, for the real impulse response of the ρ(∈[0,3])-th fractional delay filter in the b-th left-handed polarization preset beam Then the baseband digital signal of the b-th left-handed polarization preset beam

[0230]

[0231] For the real impulse response of the ρ(∈[0,3])-th fractional delay filter in the b-th right-handed polarization preset beam Then the baseband digital signal of the b-th right-handed polarization preset beam

[0232]

[0233] where the symbol represents the linear convolution operation

[0234] Step 7: According to the system cascade requirement, the baseband digital signals of the 8 left-handed polarization preset beams of the current system (at the C(≥1)-th level) The baseband digital signals of the 8 right-handed polarization preset beams And the series summation output signals of the 8 left-handed polarization preset beams of the previous level (the C-1-th level) The series summation output signals of the 8 right-handed polarization preset beams Perform a series summation operation to obtain the series summation output signals of the 8 left-handed polarization preset beams of the current system (at the C-th level) The series summation output signals of the 8 right-handed polarization preset beams

[0235] Since the series summation methods of each preset beam are the same, for the b-th preset beam, Step 7 includes the following steps:

[0236] Step 71: According to the system cascade requirement, the baseband digital signal of the b-th left-handed (or right-handed) polarization preset beam of the current unit (at the C = 1-th level) Is directly used as the series summation output signal of the b-th left-handed (or right-handed) polarization preset beam of the current unit (at the C = 1-th level)

[0237]

[0238] Step 72: According to the system cascade requirement, the baseband digital signal of the b-th right-handed (or left-handed) polarized preset beam of the current cell (at the C = 1 level) is directly used as the cascade summation output signal of the b-th right-handed (or left-handed) polarized preset beam of the current cell (at the C = 1 level)

[0239]

[0240] Step 73: According to the system cascade requirement, the baseband digital signal of the b-th left-handed polarized preset beam of the current cell (at the C (≥ 2) level) is subjected to a cascade summation operation with the cascade summation output signal of the b-th left-handed polarized preset beam of the previous cell (at the C - 1 level) to obtain the cascade summation output signal of the b-th left-handed polarized preset beam of the current cell (at the C level)

[0241]

[0242] Step 74: According to the system cascade requirement, the baseband digital signal of the b-th right-handed polarized preset beam of the current cell (at the C level) is subjected to a cascade summation operation with the cascade summation output signal of the b-th right-handed polarized preset beam of the previous cell (at the C - 1 level) to obtain the cascade summation output signal of the b-th right-handed polarized preset beam of the current cell (at the C level)

[0243]

[0244] Furthermore, according to the above technical requirements, in the broadband DBF system of the large-scale array, the sub-array beam summation sums the preset beam signals output by the 16 dual-sub-array cascade structures and by beam to obtain the final output preset beam signal and Specifically, it includes:

[0245] Step 81: The b-th left-handed polarized preset beam signal output by the u-th dual-sub-array cascade structure is Summing all the same beams of the dual-sub-array cascade structures, the b-th left-handed polarized preset beam signal can be obtained

[0246]

[0247] Step 82, the b-th right-handed polarized pre-set beam signal output by the u-th twin-array cascade structure is By summing the same beam of all twin-array cascade structures, the b-th right-handed polarized pre-set beam signal can be obtained

[0248]

[0249] Embodiment III

[0250] As Figure 9 shown, in this embodiment, the wideband RF direct sampling array has a total of M = 1024 horizontally polarized antennas and M = 1024 vertically polarized antennas, with an operating frequency band of 7.5 GHz to 8.7 GHz, and simultaneously forms 64 right-handed adaptive beams with a bandwidth of 300 MHz and a sampling rate of 400 MHz.

[0251] First, use the DBF system provided in this embodiment as a sub-array processing unit to simultaneously process 32 horizontally polarized antennas and 32 vertically polarized antennas, and simultaneously form 64 right-handed beams with a bandwidth of 300 MHz and a sampling rate of 400 MHz. Then, 32 sub-array processing units are cascaded in 2 sub-array processing units and paralleled in 16 sub-array processing units to construct a wideband DBF system for a large-scale array as Figure 6 shown.

[0252] In this embodiment, except that the time-domain multi-beam forming of the C = 1 and C = 2 level sub-array processing units is different from that of Embodiment II, the other implementation steps are the same. In this embodiment, the time-domain multi-beam synthesis is completed by using the structure as Figure 9 shown to perform channel amplitude-phase weighting and adaptive beam synthesis of the sub-array complex FIR filter.

[0253] Based on the above technical requirements, except for Step 6, the implementation steps of a single sub-array processing unit are exactly the same as those of Embodiment 2. Step 6 is specifically:

[0254] Step 6, the baseband digital signals of 32 left-handed polarized replication channels The baseband digital signals of 32 right-handed polarized replication channels Perform wideband time-domain multi-beam synthesis respectively to obtain the baseband digital signals of 8 left-handed polarized pre-set beams The baseband digital signals of 8 right-handed polarized pre-set beams

[0255] Since the wideband time-domain beam synthesis methods of 32 left-handed and right-handed polarized replication channels are the same, for the b-th pre-set beam, Step 6 includes the following steps:

[0256] Step 61. For the b-th preset beam, the ρ-th (ρ ∈ [0, 3]) amplitude-phase weighting coefficient in the k-th left-handed polarization replication channel is Then the amplitude-phase weighted output signal of the k-th left-handed polarization replication channel is

[0257]

[0258] For the b-th preset beam, the ρ-th (ρ ∈ [0, 3]) amplitude-phase weighting coefficient in the k-th right-handed polarization replication channel is Then the amplitude-phase weighted output signal of the k-th right-handed polarization replication channel is

[0259]

[0260] where n is an integer.

[0261] Step 62. When performing adaptive beamforming and the complex FIR filter compensates at the subarray level, for the ρ-th (ρ ∈ [0, 3]) complex FIR filter in the b-th left-handed polarization preset beam, the impulse response is Then the baseband digital signal of the b-th left-handed polarization preset beam is

[0262]

[0263] For the ρ-th (ρ ∈ [0, 3]) complex FIR filter in the b-th right-handed polarization preset beam, the impulse response is Then the baseband digital signal of the b-th right-handed polarization preset beam is

[0264]

[0265] where the symbol represents the linear convolution operation.

[0266] Embodiment 4

[0267] The present invention further provides a reconfigurable digital beamforming system based on a broadband radio frequency direct sampling array, including a radio frequency signal receiving module, a signal frequency conversion processing module, a signal equalization processing module, a signal data replication module, a signal polarization synthesis module, a time-domain multi-beam synthesis module, and a multi-beam output module;

[0268] The radio frequency signal receiving module is used to receive radio frequency signals through horizontal and vertical polarization array antennas, and after low-noise amplification and preselection filtering, obtain the horizontal and vertical polarization radio frequency signals input to the analog-to-digital converter;

[0269] The signal frequency conversion processing module is used to obtain the horizontal and vertical polarization baseband digital signals of each channel after the horizontal and vertical polarization radio frequency signals are processed by an analog-to-digital converter, a channel time delay device, and digital down-conversion processing;

[0270] The signal equalization processing module is used to perform channel equalization processing on the horizontal and vertical polarization baseband digital signals of each channel to obtain the horizontal and vertical polarization equalized output signals of each channel;

[0271] The signal data replication module is used to replicate the data of the horizontal and vertical polarization equalized output signals of each channel under a high-speed processing clock;

[0272] The signal polarization synthesis module is used to perform polarization synthesis on the horizontal and vertical polarization output signals of each replicated channel to obtain the left-handed and right-handed polarization output signals of each replicated channel;

[0273] The time-domain multi-beam synthesis module is used to perform time-domain multi-beam synthesis on the left-handed and right-handed polarization output signals of each replicated channel respectively to obtain the left-handed and right-handed polarization output signals of each preset beam;

[0274] The multi-beam output module is used to perform a series summation operation on the left-handed and right-handed polarization output signals of each preset beam and the upper-level beam output signals according to the series or parallel requirements to obtain the baseband digital signals of the left-handed and right-handed polarization multi-beam outputs.

[0275] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than 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: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A reconfigurable digital beamforming method based on a broadband RF direct acquisition array, characterized in that: The following steps are involved: Step 1: Receive radio frequency signals with horizontal and vertical polarization array antennas, and obtain horizontal and vertical polarization radio frequency signals input by analog-to-digital converters after low noise amplification and pre-selection filters; Step 2: After the horizontal and vertical polarized radio frequency signals are processed by an analog-to-digital converter, a channel delay device and digital down-conversion, horizontal and vertical polarized baseband digital signals of each channel are obtained; Step 3: The horizontal and vertical polarization baseband digital signals of each channel are processed by channel equalization to obtain horizontal and vertical polarization equalized output signals of each channel; Step 4, the horizontal and vertical polarization equalization output signals of each channel are replicated under a high-speed processing clock; Step 5: Perform polarization synthesis on the horizontal and vertical polarized output signals of each replica channel to obtain left-handed and right-handed polarized output signals of each replica channel; Step 6: The left-handed and right-handed polarized output signals of each replica channel are respectively subjected to time-domain multi-beam synthesis to obtain the left-handed and right-handed polarized output signals of each preset beam; Step 7: According to the requirements of series connection or parallel connection, the left-handed and right-handed polarized output signals of each preset beam are connected in series and summed with the output signal of the previous beam to obtain the baseband digital signals of the left-handed and right-handed polarized multi-beam outputs.

2. The reconfigurable digital beamforming method based on a broadband RF direct acquisition array according to claim 1 is characterized in that: The step 1 is specifically as follows: The digital array includes M horizontally polarized antennas and M vertically polarized antennas. The RF signal received by the kth horizontally polarized antenna is The RF signal received by the kth vertically polarized antenna is After the low noise amplifier and pre-selection filter, the ADC input RF signal of the kth horizontal polarization receiving channel is The ADC input RF signal of the kth vertical polarization receiving channel is 3. The reconfigurable digital beamforming method based on a broadband RF direct acquisition array according to claim 2 is characterized in that: The step 2 is specifically as follows: If the sampling frequency of the ADC is F S , RF signal of horizontal polarization channel and the RF signal of the vertically polarized channel After ADC sampling, channel delay and DDC processing, the baseband digital signal of M horizontal polarization channels can be obtained. and baseband digital signals of M vertically polarized channels Among them, the sampling frequency of the baseband digital signal is F DS , satisfying D=F S / F DS is a positive integer; The step 2 further comprises the following steps: Step 21, use sampling frequency F S For the RF signal of the kth horizontal polarization channel and the RF signal of the kth vertically polarized channel By performing RF direct sampling, the RF digital signal of the kth horizontal polarization channel can be obtained. and the RF digital signal of the kth vertically polarized channel Where t represents continuous time, which is the time variable of the RF signal, and m represents the discrete time index, which is the sampling point after RF sampling; Step 22: Delay error of the kth horizontal polarization channel measured in advance and the delay error of the kth vertically polarized channel Then the channel delay output signal of the kth horizontal polarization channel is for: The channel delay output signal of the kth vertical polarization channel for: in, Indicates the k-th horizontal polarization channel delay error The corresponding integer sample value, is the kth vertical polarization channel delay error The corresponding integer sample value can be expressed using the following logic and Among them, round(·) indicates rounding operation; Step 23: Calculate the digital mixing angular frequency ω of the digital down-conversion according to the operating frequency band, ADC sampling frequency, and baseband digital signal sampling frequency. RF , integer extraction multiple D = F S / F DS , according to the system bandwidth requirements, design the programmable real low-pass filter coefficient h LP (m), then the DDC output signal s of the kth horizontal polarization channel is H,k (n) is: The DDC output signal s of the kth vertically polarized channel V,k (n) is: Among them, the symbol Represents a linear convolution operation.

4. The reconfigurable digital beamforming method based on a broadband RF direct acquisition array according to claim 3 is characterized in that: The step 3 is specifically as follows: Based on the equalizer impulse response of M horizontal polarization channels measured in advance The impulse response of the equalizer for M vertically polarized channels DDC output signal for M horizontal polarization channels And the DDC output signal of M vertically polarized channels After equalization processing, the equalized output signal of M horizontal polarization channels can be obtained. and the balanced output signal of M vertically polarized channels The step 3 also includes the following steps: Step 31: according to the equalizer impulse response g of the k-th horizontal polarization channel H,k (n), the DDC output signal s for the kth horizontal polarization channel H,k (n) is equalized, then the equalized output signal x of the kth horizontal polarization channel is H,k (n) is: Step 32: according to the equalizer impulse response g of the kth vertical polarization channel V,k (n), the DDC output signal s for the kth vertically polarized channel V,k (n) is equalized, then the equalized output signal x of the kth vertical polarization channel is V,k (n) is:

5. The reconfigurable digital beamforming method based on a broadband RF direct acquisition array according to claim 4 is characterized in that: The step 4 is specifically as follows: Given a system high-speed processing clock frequency F CS and the preset number of beams B, B ≥ 1, according to the actual number of beams B r =δ·B, the balanced output signal of M horizontal polarization channels Balanced output signal of M vertically polarized channels Perform data replication to obtain baseband digital signals of M horizontal polarization replication channels Baseband digital signal of M vertical polarization replication channels The step 4 also includes the following steps: Step 41: The equalized output signal x of the kth horizontal polarization channel is converted to H,k (n) Data replication is performed, then the baseband digital signal of the k-th horizontal polarization replication channel is for: Where ρ represents the copy channel count value, S represents the maximum number of copy channels, and S = F CS / F DS , δ represents the ratio of the actual number of beams to the preset number of beams, and takes a value in the interval [1, S]; Step 42, the equalized output signal x of the kth vertical polarization channel V,k (n) Data replication is performed, then the baseband digital signal of the kth vertical polarization replication channel is for:

6. The reconfigurable digital beamforming method based on a broadband RF direct acquisition array according to claim 5 is characterized in that: The step 5 is specifically as follows: According to the system polarization requirements, set the two-dimensional polarization synthesis matrix corresponding to M horizontal and vertical polarization replication channels in advance The baseband digital signal of M horizontal polarization replication channels can be Baseband digital signal of M vertical polarization replication channels Perform polarization synthesis to obtain the baseband digital signal of M left-handed polarization replication channels Baseband digital signal of M right-hand polarization replication channels The step 5 also includes the following steps: Step 51: The pth two-dimensional polarization synthesis matrix in the kth horizontal and vertical polarization replication channel for: in, They are the two-dimensional polarization synthesis matrices The four elements of , ρ∈[0,S-1]; Step 52: The baseband digital signal of the k-th horizontal polarization replication channel Baseband digital signal of the kth vertical polarization replica channel By performing polarization synthesis, the baseband digital signal of the kth left-handed polarized replica channel can be obtained. Step 53: The baseband digital signal of the k-th horizontal polarization replication channel Baseband digital signal of the kth vertical polarization replica channel By performing polarization synthesis, the baseband digital signal of the kth right-hand polarization replica channel can be obtained.

7. The reconfigurable digital beamforming method based on a broadband RF direct acquisition array according to claim 6 is characterized in that: The step 6 is specifically as follows: Baseband digital signal of M left-hand polarization replication channels Baseband digital signal of M right-hand polarization replication channels Broadband time-domain multi-beam synthesis is performed separately to obtain baseband digital signals of B left-handed polarization preset beams. Baseband digital signal of B right-hand polarization preset beams The step 6 also includes the following steps: Step 61: For the b-th preset beam, the p-th amplitude-phase weighting coefficient in the k-th left-handed polarization replication channel is Then the amplitude-phase weighted output signal of the kth left-handed polarization replica channel is It can be expressed as: For the b-th preset beam, the ρ-th amplitude-phase weighting coefficient in the k-th right-hand polarization replication channel is Then the amplitude-phase weighted output signal of the kth right-hand polarization replica channel is It can be expressed as: Step 62: When conventional beamforming is performed and the fractional delay filter is compensated at the channel level, for the b-th preset beam, the real impulse response of the p-th fractional delay filter in the k-th left-handed polarization replica channel is Then the baseband digital signal of the bth left-handed polarization preset beam is It can be expressed as: For the b-th preset beam, the real impulse response of the ρ-th fractional delay filter in the k-th right-hand polarization replica channel is Then the baseband digital signal of the bth right-hand polarization preset beam is It can be expressed as: Step 63: When conventional beamforming is performed and the fractional delay filter is compensated at the subarray level, the real impulse response of the pth fractional delay filter in the bth left-handed polarization preset beam is Then the baseband digital signal of the bth left-handed polarization preset beam is It can be expressed as: The real impulse response of the ρth fractional delay filter in the bth right-hand polarization preset beam is Then the baseband digital signal of the bth right-hand polarization preset beam is It can be expressed as: Step 64: When adaptive beamforming is performed and the complex FIR filter is compensated at the subarray level, the impulse response of the pth complex FIR filter in the bth left-handed polarization preset beam is Then the baseband digital signal of the bth left-handed polarization preset beam is It can be expressed as: The impulse response of the ρth complex FIR filter in the bth right-handed polarization preset beam is Then the baseband digital signal of the bth right-hand polarization preset beam is It can be expressed as:

8. The reconfigurable digital beamforming method based on a broadband RF direct acquisition array according to claim 7 is characterized in that: The step 7 is specifically as follows: According to the system parallel or series requirements, the baseband digital signal of the B left-handed polarization preset beams of the current system at level C can be Baseband digital signal of B right-hand polarization preset beams The output signal of the series summation of B left-handed polarization preset beams of level C-1 The output signal of the series summation of B right-hand polarization preset beams Perform a series summation operation to obtain the series summation output signal of the B left-handed polarization preset beams in the current system at the Cth level The output signal of the series summation of B right-hand polarization preset beams The step 7 also includes the following steps: Step 71: According to the system series connection requirement, when the current unit is at the C=1 level, the baseband digital signal of the bth left-handed polarization preset beam of the current unit is Directly used as the series summation output signal of the bth left-handed polarization preset beam of the current unit Step 72: According to the system series connection requirement, when the current unit is at the C=1 level, the baseband digital signal of the bth right-handed polarization preset beam of the current unit is Directly used as the series summation output signal of the bth right-hand polarization preset beam of the current unit Step 73: According to the system series connection requirement, when the current unit is at level C≥2, the baseband digital signal of the bth left-handed polarization preset beam of the current unit is The output signal of the series summation of the bth left-handed polarization preset beam of the previous unit Perform a series summation operation to obtain the series summation output signal of the bth left-handed polarization preset beam of the current unit Step 74: According to the system series connection requirement, when the current unit is at level C≥2, the baseband digital signal of the bth right-handed polarization preset beam of the current unit is The output signal of the series summation of the bth right-handed polarization preset beam of the previous unit Perform a series summation operation to obtain the series summation output signal of the bth right-hand polarization preset beam of the current unit 9. The reconfigurable digital beamforming method based on a broadband RF direct acquisition array according to claim 8 is characterized in that: The step 7 also includes the following steps: Step 75: According to the system parallel connection requirement, the baseband digital signal of the bth left-handed polarization preset beam is Directly used as the series summation output signal of the bth left-handed polarization preset beam Step 76: According to the system parallel connection requirement, the baseband digital signal of the bth right-hand polarization preset beam is Directly used as the series summation output signal of the bth right-hand polarization preset beam 10. A reconfigurable digital beamforming system based on a broadband RF direct acquisition array, characterized in that: It includes a radio frequency signal receiving module, a signal frequency conversion processing module, a signal equalization processing module, a signal data replication module, a signal polarization synthesis module, a time domain multi-beam synthesis module and a multi-beam output module; The radio frequency signal receiving module is used to receive radio frequency signals from horizontal and vertical polarized array antennas, and obtain horizontal and vertical polarized radio frequency signals input by analog-to-digital converters after low-noise amplification and pre-selection filters; The signal frequency conversion processing module is used to obtain horizontal and vertical polarization baseband digital signals of each channel after the horizontal and vertical polarization radio frequency signals are processed by analog-to-digital converters, channel delay devices and digital down-conversion; The signal equalization processing module is used for performing channel equalization processing on the horizontal and vertical polarization baseband digital signals of each channel to obtain the horizontal and vertical polarization equalized output signals of each channel; The signal data replication module is used to replicate the horizontal and vertical polarization balanced output signals of each channel under a high-speed processing clock; The signal polarization synthesis module is used to perform polarization synthesis on the horizontal and vertical polarization output signals of each replication channel to obtain left-handed and right-handed polarization output signals of each replication channel; The time domain multi-beam synthesis module is used to perform time domain multi-beam synthesis on the left-handed and right-handed polarized output signals of each replica channel, respectively, to obtain the left-handed and right-handed polarized output signals of each preset beam; The multi-beam output module is used to perform series connection and summation operations on the left-handed and right-handed polarized output signals of each preset beam and the previous-stage beam output signal according to the requirements of series connection or parallel connection, so as to obtain baseband digital signals of left-handed and right-handed polarized multi-beam outputs.

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