Channel device based on secondary multiphase decomposition and data extraction

Abstract

The invention relates to a channelization device based on secondary polyphase decomposition and data extraction, which comprises an input commutation device, a plurality of filter banks, a plurality of output combiner and an inverse Fourier transform module, and is characterized in that the input commutation device is respectively connected with each filter bank, each filter bank comprises a plurality of sub-filters, and each sub-filter comprises a plurality of sub-filters; each sub-filter is connected with a corresponding output combiner, each output combiner is connected with an inverse Fourier transform module, an input reversing device delays original broadband signals and extracts the original broadband signals by a preset extraction multiple, and the sub-filters perform convolution operation on the signals input into the sub-filters and output the signals after convolution. The output combiner is used for combining signals output by the sub-filters, the inverse Fourier transform module carries out complex modulation on the combined signals output by the output combiner so as to equivalently carry out complex modulation on the original low-pass filter to obtain a plurality of narrow-band signals, and the number of the narrow-band signals is the same as that of the filter banks; the preset extraction multiple is smaller than the number of the narrowband signals.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and more particularly to a channelizer based on secondary multi-phase decomposition and data extraction. Background Art

[0002] With the development of science and technology, in the fields of communication systems, radio astronomy, real-time signal processing, etc., the signal bandwidth that needs to be processed is getting larger and larger. In order to complete the complete signal processing task, it is necessary to divide the wider input bandwidth into several narrower sub-bands for further processing and analysis. Channelizer is a device used to divide a broadband continuous signal into multiple narrowband signals (i.e. channels). It has important applications in many fields such as satellite communication, radar signal processing, wireless communication, etc.

[0003] The existing channelizer has the problem of attenuation of edge signals within the sub-band and spectrum aliasing due to its maximum decimation characteristic (ie, the decimation factor of the decimator is the same as the number of channels), which limits the performance of the channelizer. Summary of the invention

[0004] The object of the present invention is to provide a channelizer based on secondary polyphase decomposition and data extraction to solve the problems of sub-band edge signal attenuation and spectrum aliasing.

[0005] Based on the above purpose, the present invention provides a channelizer based on secondary multi-phase decomposition and data extraction, including an input commutation device, a plurality of filter groups, a plurality of output combiners and an inverse Fourier transform module, each filter group corresponds to each output combiner one by one, the input commutation device is respectively connected to each filter group in communication, each filter group includes a plurality of sub-filters, each sub-filter of each filter group is connected to the output combiner corresponding to the filter group in communication, each output combiner is respectively connected to the inverse Fourier transform module in communication, the input commutation device is used to receive an original broadband signal, and delay the original broadband signal and extract it by a preset extraction multiple, so as to obtain a signal of the original broadband signal. The original broadband signal is input into each sub-filter of each filter group according to a preset phase order, the sub-filter is used to perform a convolution operation on the input signal and output the convolved signal, the output combiner is used to combine the convolved signals output by each sub-filter connected to the output combiner and output a combined signal, the inverse Fourier transform module is used to perform complex modulation on the combined signal output by each output combiner, so as to equivalently perform complex modulation on the original low-pass filter to obtain a plurality of narrowband signals, wherein the number of the narrowband signals is the same as the number of the filter groups, and the preset decimation multiple is less than the number of the narrowband signals.

[0006] Furthermore, the number of sub-filters included in each filter group is equal to the preset decimation factor divided by the greatest common divisor of the preset decimation factor and the number of the narrowband signals.

[0007] Furthermore, the input merger is an adder, which is used to add the convolved signals output by the sub-filters of the corresponding filter group to obtain a merged signal.

[0008] Furthermore, the number of points of the inverse Fourier transform module is equal to the number of narrowband signals.

[0009] Furthermore, the input switching device includes multiple first delay devices and multiple extractors, each first delay device corresponds one-to-one to each extractor, each extractor corresponds one-to-one to each sub-filter of each filter group, each first delay device is communicatively connected to the corresponding extractor, each extractor is communicatively connected to the corresponding sub-filter, the extraction multiple of each extractor is the preset extraction multiple, the delay bit number of each first delay device is different, and is set in sequence according to preset rules.

[0010] Further, the input commutation device includes a commutator and a plurality of second delay groups, the commutator has an input end and a plurality of output ends, the number of the output ends is the same as the preset extraction multiple, the input end is used to receive the original broadband signal, each second delay group corresponds to each output end one by one, and each output end is communicatively connected to the input end of the corresponding second delay group;

[0011] Each second delay device group includes multiple second delay devices which are communicatively connected in sequence, and the number of second delay devices is equal to the preset extraction multiple divided by the greatest common divisor of the preset extraction multiple and the number of narrowband signals; the number of delay bits of each second delay device is 1, and the input and output ends of each second delay device are respectively formed as signal output ends, and each signal output end is respectively communicatively connected to each sub-filter of each filter group.

[0012] Furthermore, it also includes a cyclic shifter, which is provided between each output combiner and the inverse Fourier transform module, and is respectively communicated with each output combiner and the inverse Fourier transform module, and the cyclic shifter is used to perform upward cyclic shift on each combined signal output by each output combiner, and input each shifted signal into the inverse Fourier transform module to avoid frequency offset.

[0013] Furthermore, the number of bits R(n) cyclically shifted upward at the nth time by the cyclic shifter is:

[0014] R(n)=(nD)modM, n=0, 1, 2,...

[0015] Wherein, D is the preset decimation multiple, and M is the number of narrowband signals.

[0016] Furthermore, R(n) is periodic, and its period T is:

[0017] T=M / l, where l is the greatest common divisor of M and D.

[0018] The channelizer based on secondary polyphase decomposition and data extraction of the present invention sets the extraction multiple to be less than the number of channels so that there is overlap between the narrowband signals, thereby solving the problem of attenuation and spectrum aliasing of the signals at the edge of the sub-band of the existing channelizer; the overlapping polyphase filter group based on secondary polyphase decomposition and data extraction realizes channelization, has a simple structure, can be completely constructed using the existing IP core (i.e., a pre-designed circuit function module) in FPGA (field programmable gate array), and is simple to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of a channelizer based on secondary multiphase decomposition and data extraction according to an embodiment of the present invention;

[0020] Figure 2 A first structural schematic diagram of an input switching device of a channelizer based on secondary multi-phase decomposition and data extraction according to an embodiment of the present invention;

[0021] Figure 3 A second structural schematic diagram of an input switching device of a channelizer based on secondary multi-phase decomposition and data extraction according to an embodiment of the present invention;

[0022] Figure 4 is a schematic diagram of an input switching device having a second structure according to an exemplary embodiment of the present invention;

[0023] Figure 5 A schematic structural diagram of a channelizer based on secondary multiphase decomposition and data extraction according to another embodiment of the present invention;

[0024] Figure 6 Detailed description is given of an implementation structure of a cyclic shifter of a channelizer based on secondary polyphase decomposition and data extraction according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0026] like Figure 1As shown, an embodiment of the present invention provides a channelizer based on secondary multiphase decomposition and data extraction, which includes an input commutation device 100, a plurality of filter groups 200, a plurality of output mergers 300 and an inverse Fourier transform module 400, each filter group 200 corresponds to each output merger 300 one by one, the input commutation device 100 is respectively connected to each filter group 200 in communication, each filter group 200 includes a plurality of sub-filters 210, each sub-filter 210 of each filter group 200 is connected to the output merger 300 corresponding to the filter group 200 in communication, each output merger 300 is respectively connected to the inverse Fourier transform module 400 in communication, the input commutation device 100 is used to receive an original broadband signal, and delay the original broadband signal and extract it by a preset extraction multiple, so that the original broadband signal is input to each sub-filter 210 of each filter group 200 in a preset phase sequence, and the sub-filter 210 of each filter group 200 is connected to the output merger 300 corresponding to the filter group 200. 210 is used to perform convolution operation on the signal input thereto and output the convolved signal. Each output combiner 300 is used to combine the convolved signals output by each sub-filter 210 connected to the output combiner 300 and output a combined signal. The inverse Fourier transform module 400 is used to perform equivalent complex modulation on the combined signal output by each output combiner 300, so as to equivalently perform complex modulation on the original low-pass filter and thus obtain multiple narrowband signals, wherein the number of narrowband signals is the same as the number of filter groups, and the preset extraction multiple is less than the number of narrowband signals, thereby allowing overlap between the narrowband signals, so that the out-of-band signals can be well suppressed. At the same time, the attenuation of the edge signals in the band is generated in the overlapping part between the introduced sub-bands, which will not affect the effective frequency band. When processing the signal in the post-processing stage, only the frequency range required by each sub-band needs to be processed, and the redundant part introduced by the overlapping structure can be eliminated. This only appropriately increases the hardware implementation complexity of the channelizer for ultra-wideband signals, improves the flatness of the amplitude-frequency response within the sub-band, greatly suppresses the spectrum aliasing caused by extraction, and improves the quality of the signal after channelization. In the present invention, each sub-filter is equivalent to multiple groups of bandpass filters after being combined twice and combined with the inverse Fourier transform module 400, thereby realizing the channelization of the original wideband signal.

[0027] The number of filter groups 200 is denoted as M, the original broadband signal is denoted as x(n), and the decimation multiple of the original broadband signal by the input commutation device 100 (i.e., the preset decimation multiple) is denoted as D. The greatest common factor of M and D is l. Dividing D by l, we can get d, i.e., D=l*d, where d is the number of sub-filters 210 contained in each filter group 200. After x(n) enters the input commutation device 100, the input commutation device 100 will delay and decimate it by D times so that it can be input into each sub-filter 210 according to the preset phase sequence and reduce the data rate of the output signal; the input commutation device 100 will convert x(n) into M groups of signal outputs, each group of signals corresponds to a filter group 200, and each group of signals includes d sub-signals, and the d sub-signals correspond to d sub-filters respectively. As shown in FIG. Figure 1 As shown, the first group of signals includes signals A0, A M ...A (d-1)M The second group of signals includes signals A1, A M+ 1...A (d-1)M+1 The third group of signals includes signals A2, A M+2 ...A (d-1)M+2 , and so on, the Mth group of signals includes signal A M-1 , A M+(M -1)...A (d-1)M+(M-1) , where signal A i The subscript i in the above formula refers to the number of delay bits. For example, A0 refers to the signal obtained by sampling x(n) with a delay of 0 bits (i.e., no delay) and decimating the collected signal by D times. A1 refers to the signal obtained by sampling x(n) with a delay of 1 bit and decimating the collected signal by D times. M-1 Refers to the signal obtained by sampling x(n) with a delay of M-1 bits and decimating the collected signal by D times. To facilitate the description of the rules between the number of delayed bits of each signal, the subscript values ​​of each group of signals can be combined into a matrix, where the subscripts of each sub-signal of each group of signals form the rows of the matrix, the first group of signals is the first row, the second group is the second row, and so on. In this matrix, the subscripts of the sub-signals of the same bit of each group of signals form the columns of the matrix, that is, the subscript of the first sub-signal of each group of signals is the first column of the matrix, the subscript of the second sub-signal of each group of signals is the second column of the matrix, and so on. Therefore, the dimension of the matrix is ​​M*d, the difference between any two adjacent subscripts in each row is M, and the difference between any two adjacent subscripts in each column is 1.

[0028] The input combiner 300 is an adder, which is used to add the signals output by the sub-filters 210 of the corresponding filter bank 200 to obtain a combined signal B. j(j=0,1,2...M-1), for example, the first input combiner 300 is used to add the sub-filters 210 of the first filter bank 200 to obtain B0, the second input combiner 300 is used to add the sub-filters 210 of the second filter bank 200 to obtain B1, and so on, the Mth input combiner 300 is used to add the sub-filters 210 of the Mth filter bank 200 to obtain B M-1 .

[0029] The inverse Fourier transform module 400 is used to transform each merged signal B j Equivalent complex modulation is performed to equivalently perform complex modulation on the original low-pass filter to output narrowband signals of different sub-bands. The number of narrowband signals is the same as the number of filter banks 200, that is, the inverse Fourier transform module 400 can output narrowband signals of M frequency bands, which are y0(n), y1(n), y2(n)...y M-1 (n) The inverse Fourier transform module 400 is an M-point inverse Fourier transform module, which is used to perform inverse Fourier transform on each combined signal to achieve complex modulation on each combined signal.

[0030] like Figure 2 As shown, in some embodiments, the input commutation device 100 may include a plurality of first delay devices 110 and a plurality of extractors 120, each first delay device 110 corresponds one-to-one to each extractor 120, and each extractor 120 corresponds one-to-one to each sub-filter 210 of each filter group 200, so there are d*M first delay devices 110 and extractors 120, each first delay device 110 is communicatively connected to the corresponding extractor 120, each extractor 120 is communicatively connected to the corresponding sub-filter 210, and the extraction multiple of each extractor 120 is D, and the delay bit number of each first delay device 110 is different, and is arranged in sequence according to a preset rule, so that the original broadband signal is input to each sub-filter 210 of each filter group 200 according to a preset phase order. Specifically, each first delay device 110 can be divided into M first delay device groups, each first delay device group includes d first delay devices 110, each first delay device group corresponds to each filter group 200 one by one, each first delay device 110 in each first delay device group corresponds to each filter 210 of the corresponding filter group 200, and the delay bit number of each first delay device in each first delay device group is the same as the input signal A of the filter group 200. i corresponds to the subscript i of . Figure 2 In, z -i That is, it means a delay of i bits, and “↓D” means extracting the signal, and the extraction multiple (or extraction factor) is D.

[0031] like Figure 3As shown, in some embodiments, the input switching device 100 may include a switch 130 and a plurality of second delay groups 140, the switch 130 having an input end and D output ends, the input end being used to receive the original broadband signal, the second delay groups 140 also being D, the D output ends of the switch 130 being respectively connected to the input ends of the second delay groups 140 for communication, each second delay group 140 including d second delays 141 connected in sequence for communication, each second delay 141 having a plurality of second delays ... The number of delay bits is 1, and the input and output ends of each second delay device 141 are respectively formed as signal output ends 142. For the second delay devices 141 connected to each other, the output end of the upstream second delay device 141 is connected to the input end of the downstream second delay device 141, so only one signal output end 142 is formed at these two ends. The number of signal output ends 142 is d*M, which corresponds to the number of each sub-filter 210. Each signal output end 142 is respectively connected to each sub-filter 210. In other words, the functions of delay and D-fold extraction can also be realized by a commutator 130 and multiple second delay device groups 140.

[0032] like Figure 4 As shown in an exemplary embodiment, M=8, D=6, the greatest common factor of M and D is l=2, d=D / l=3, and a commutator with 6 output terminals and a second delay device with 18 delay bits can output 24 signals, namely signals A0~A1. 23 , whose subscript is Figure 1 The subscripts of the signals Ai in are the same, and the corresponding sub-filter 210 can be found through the subscripts of the signals, and then the signal output end that outputs the signal can be communicatively connected with the sub-filter 210 corresponding to the signal.

[0033] In the above-mentioned channelizer based on secondary polyphase decomposition and data extraction, since the decimation factor D is less than the number of narrowband signals (i.e., the number of channels) M, the spectrum of the channelized signal will be periodically extended at the new sampling rate. In the existing channelizer based on secondary polyphase decomposition and data extraction, the decimation factor D is equal to the number of channels M. Assuming that the sampling rate of the original wideband signal is fs, the spectrum of each subband will be downsampled by fs / M times during output, and the sampling rate of the output data of each subband is fs / M. In the frequency domain, the frequency of each subband will be extended with a period of fs / M. The center frequency of the retained band of the kth subband after passing through the filter is kfs / M, which is an integer multiple of fs / M. Therefore, after the periodic extension of the spectrum, its center frequency will be moved to zero frequency.

[0034] In the channelizer based on secondary multiphase decomposition and data extraction of the present invention, the center frequency of each sub-band remains unchanged, but the sampling frequency of the signal will be increased, and the center frequency of each sub-band is no longer an integer multiple of the sampling frequency. This will make it impossible for the center frequency of each output sub-band to reach zero frequency through the periodic extension of the spectrum after extraction, resulting in frequency offset, which will affect the subsequent signal processing. Based on this, if Figure 5 As shown, another embodiment of the present invention provides a channelizer based on secondary multiphase decomposition and data extraction, which adds a cyclic shifter 500 on the basis of the above-mentioned channelizer based on secondary multiphase decomposition and data extraction, and the cyclic shifter 500 is used to output each merged signal B at each moment. j A cyclic shift is performed, and then each shifted signal is input into the inverse Fourier transform module 400 to avoid frequency offset.

[0035] The number of bits R(n) shifted upward at the nth moment is:

[0036] R(n)=(nD)modM, n=0, 1, 2,...

[0037] R(n) is periodic, and its period T can be expressed as:

[0038]

[0039] In this way, after each combined signal B j Before entering the inverse Fourier transform module 400, an upward circular shift is performed to reorder the data, and then the reordered signal data is input into the inverse Fourier transform module 400. At this time, when performing complex modulation calculation, the input signal in each item of the summation will no longer be the same as multiplication, but with Multiplying by , the output signal p of the k-th subband of the channelizer based on secondary polyphase decomposition and data extraction after the introduction of the cyclic shifter 500 can be expressed as:

[0040]

[0041] where v k (n) represents the output data of the k-th multi-phase element at the n-th moment.

[0042] This is equivalent to down-converting the original final output signal of the kth sub-band and shifting its spectrum downward by kfs / M, which just moves its center frequency from kfs / M to zero frequency, solving the problem of frequency offset.

[0043] Figure 6The specific implementation structure of the cyclic shifter 500 of the channelizer based on secondary multi-phase decomposition and data extraction when M is equal to 5 and D is equal to 3 is shown. The cyclic shifter 500 cyclically switches between five shift states. In the five shift states, the number of bits shifted upward by the cyclic shifter 500 is 0, 2, 4, 1, and 3 respectively.

[0044] In the channelizer based on secondary polyphase decomposition and data extraction of the embodiment of the present invention, the extraction multiple D is less than the number of channels M, so that there is overlap between the narrowband signals, thereby solving the problem of attenuation and spectrum aliasing of the signals at the edge of the sub-band of the existing channelizer; the overlapping polyphase filter group based on secondary polyphase decomposition and data extraction realizes channelization, has a simple structure, can be completely constructed using the existing IP core (i.e., a pre-designed circuit function module) in FPGA (field programmable gate array), and is easy to implement.

[0045] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A channelizer based on secondary multiphase decomposition and data extraction, characterized in that: The invention comprises an input switching device, a plurality of filter groups, a plurality of output combiners and an inverse Fourier transform module, wherein each filter group corresponds to each output combiner one by one, the input switching device is respectively connected to each filter group in communication, each filter group comprises a plurality of sub-filters, each sub-filter of each filter group is connected to the output combiner corresponding to the filter group in communication, each output combiner is respectively connected to the inverse Fourier transform module in communication, the input switching device is used to receive an original broadband signal, and delay the original broadband signal and extract it by a preset extraction multiple, so that the original broadband signal is output according to a preset phase. The sub-filters of each filter group are sequentially input, the sub-filters are used to perform convolution operation on the signals input thereto and output the convolved signals, the output combiner is used to combine the convolved signals output by the sub-filters connected to the output combiner and output a combined signal, the inverse Fourier transform module is used to perform complex modulation on the combined signals output by the output combiners, so as to equivalently perform complex modulation on the original low-pass filter to obtain multiple narrow-band signals, wherein the number of the narrow-band signals is the same as the number of the filter groups, and the preset decimation multiple is less than the number of the narrow-band signals.

2. The channelizer based on secondary multiphase decomposition and data extraction according to claim 1, characterized in that: The number of sub-filters included in each filter group is equal to the preset decimation factor divided by the greatest common divisor of the preset decimation factor and the number of the narrowband signals.

3. The channelizer based on secondary multiphase decomposition and data extraction according to claim 1, characterized in that: The input combiner is an adder, which is used to add the convolved signals output by the sub-filters of the corresponding filter group to obtain a combined signal.

4. The channelizer based on secondary multiphase decomposition and data extraction according to claim 1, characterized in that: The number of points of the inverse Fourier transform module is equal to the number of narrowband signals.

5. The channelizer based on secondary multiphase decomposition and data extraction according to claim 1, characterized in that: The input switching device includes multiple first delay devices and multiple extractors, each first delay device corresponds to each extractor one-to-one, each extractor corresponds to each sub-filter of each filter group one-to-one, each first delay device is communicatively connected to the corresponding extractor, each extractor is communicatively connected to the corresponding sub-filter, the extraction multiple of each extractor is the preset extraction multiple, the delay bit number of each first delay device is different, and is set in sequence according to preset rules.

6. The channelizer based on secondary polyphase decomposition and data extraction according to claim 1, characterized in that: The input commutation device comprises a commutator and a plurality of second delay groups, the commutator having an input end and a plurality of output ends, the number of the output ends being the same as the preset extraction multiple, the input end being used to receive the original broadband signal, each second delay group corresponding to each output end one by one, and each output end being communicatively connected to the input end of the corresponding second delay group; Each second delay device group includes multiple second delay devices which are communicatively connected in sequence, and the number of second delay devices is equal to the preset extraction multiple divided by the greatest common divisor of the preset extraction multiple and the number of narrowband signals; the number of delay bits of each second delay device is 1, and the input and output ends of each second delay device are respectively formed as signal output ends, and each signal output end is respectively communicatively connected to each sub-filter of each filter group.

7. The channelizer based on secondary polyphase decomposition and data extraction according to claim 1, characterized in that: It also includes a cyclic shifter, which is arranged between each output combiner and the inverse Fourier transform module, and is respectively communicated with each output combiner and the inverse Fourier transform module. The cyclic shifter is used to perform upward cyclic shift on each combined signal output by each output combiner, and input each shifted signal into the inverse Fourier transform module to avoid frequency offset.

8. The channelizer based on secondary multiphase decomposition and data extraction according to claim 7, characterized in that: The number of bits R(n) that the cyclic shifter cyclically shifts upward at time n is: R(n)=(nD)modM, n=0, 1, 2,... Wherein, D is the preset decimation multiple, and M is the number of narrowband signals.

9. The channelizer based on secondary polyphase decomposition and data extraction according to claim 8, characterized in that: R(n) is periodic, and its period T is: T=M / l, where l is the greatest common divisor of M and D.

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