WO2015087495A1 - デジタルフィルタ装置、デジタルフィルタ処理方法及びデジタルフィルタプログラムが記憶された記憶媒体 - Google Patents
デジタルフィルタ装置、デジタルフィルタ処理方法及びデジタルフィルタプログラムが記憶された記憶媒体 Download PDFInfo
- Publication number
- WO2015087495A1 WO2015087495A1 PCT/JP2014/005802 JP2014005802W WO2015087495A1 WO 2015087495 A1 WO2015087495 A1 WO 2015087495A1 JP 2014005802 W JP2014005802 W JP 2014005802W WO 2015087495 A1 WO2015087495 A1 WO 2015087495A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- block
- data
- overlap
- time domain
- processing
- Prior art date
Links
Images
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
- G06F17/141—Discrete Fourier transforms
- G06F17/142—Fast Fourier transforms, e.g. using a Cooley-Tukey type algorithm
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F11/00—Error detection; Error correction; Monitoring
- G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
- G06F11/0703—Error or fault processing not based on redundancy, i.e. by taking additional measures to deal with the error or fault not making use of redundancy in operation, in hardware, or in data representation
- G06F11/0706—Error or fault processing not based on redundancy, i.e. by taking additional measures to deal with the error or fault not making use of redundancy in operation, in hardware, or in data representation the processing taking place on a specific hardware platform or in a specific software environment
- G06F11/0721—Error or fault processing not based on redundancy, i.e. by taking additional measures to deal with the error or fault not making use of redundancy in operation, in hardware, or in data representation the processing taking place on a specific hardware platform or in a specific software environment within a central processing unit [CPU]
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F11/00—Error detection; Error correction; Monitoring
- G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
- G06F11/0703—Error or fault processing not based on redundancy, i.e. by taking additional measures to deal with the error or fault not making use of redundancy in operation, in hardware, or in data representation
- G06F11/0751—Error or fault detection not based on redundancy
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H17/00—Networks using digital techniques
- H03H17/02—Frequency selective networks
- H03H17/0211—Frequency selective networks using specific transformation algorithms, e.g. WALSH functions, Fermat transforms, Mersenne transforms, polynomial transforms, Hilbert transforms
- H03H17/0213—Frequency domain filters using Fourier transforms
Definitions
- the present invention relates to arithmetic processing in digital signal processing, and more particularly to a digital filter device, a digital filter processing method, and a storage medium in which a digital filter program is stored.
- FFT Fast Fourier Transform
- FDE frequency domain equalization
- IFFT inverse fast Fourier transform
- Patent Document 1 describes “twist multiplication” described later, that is, multiplication using a twist coefficient.
- Non-Patent Document 1 As an efficient FFT / IFFT processing method, for example, the Cooley-Tukey butterfly operation described in Non-Patent Document 1 is famous. However, since the FFT / IFFT processing method by Cooley-Tukey has a large number of points, a circuit for realizing the processing method becomes complicated. For this reason, for example, the Prime / Factor method described in Non-Patent Document 2 is used to perform decomposition into two small FFT / IFFT, and FFT / IFFT processing is performed.
- FIG. 7 shows a 64-point FFT data flow 500 that has been decomposed into a two-stage butterfly process with a base 8 using, for example, the Prime-Factor method.
- the data flow 500 includes a total of 16 radix-8 butterfly computation processing and twist multiplication processing 504 including data rearrangement processing 501 and butterfly computation processing 502 and 503.
- 8 data parallel when FFT devices that perform FFT processing in parallel on 8 data (hereinafter simply referred to as “8 data parallel”) are created as physical circuits, a total of 8 A 64-point FFT process can be realized by repeating the process once.
- the eight repeated processes are processes in which partial data flows 505a to 505h performed on eight pieces of data are performed in order, and are specifically performed as follows. That is, the process corresponding to the partial data flow 505a is performed first time, the process corresponding to the partial data flow 505b is performed second time, and the process corresponding to the partial data flow 505c (not shown) is performed third time. Is done. Thereafter, similarly, processing up to the eighth partial data flow 505h is sequentially performed. With the above processing, 64-point FFT processing is realized.
- Patent Document 2 discloses an FFT apparatus that rearranges data using RAM in butterfly computation.
- Patent Document 3 discloses a high-speed technology based on parallel processing of butterfly operations.
- processing block a set of continuous input data (hereinafter referred to as “processing block”) is periodically repeated.
- processing block a set of continuous input data
- overlap method can be cited as a technique for solving this problem.
- adjacent processing blocks are overlapped by a predetermined number of data, and FFT processing is performed.
- the data after the FFT processing is subjected to filter processing and reconverted into a time domain signal by IFFT processing.
- the partial data of the both ends in which the calculation distortion produced in the overlapped process block are removed.
- a portion to be removed is referred to as a “removed portion”
- a portion that is output without being removed is referred to as an “output portion”.
- FIG. 8 is a block diagram illustrating a configuration example of a digital filter circuit 700 using an overlap FDE method.
- the digital filter circuit 700 is a frequency domain filter circuit that performs filter processing in the frequency domain. Specifically, a time domain signal input as input data is converted into frequency domain data by FFT and then subjected to filtering. The filtered signal is reconverted into a time domain signal by IFFT and output as an output signal.
- the digital filter circuit 700 includes an overlap addition circuit 710, an FFT circuit 711, a filter operation circuit 712, an IFFT circuit 713, and an overlap removal circuit 714.
- the overlap adding circuit 710 sequentially generates a block composed of N pieces of data (N is a positive integer) from the input data which is an input signal in the time domain, and outputs the block to the FFT circuit 711. At this time, the overlap adding circuit 710 causes each block to overlap the previous block by M data (M is a positive integer).
- M is a positive integer
- the number M of the number of data to be overlapped is hereinafter referred to as “overlap amount”.
- the overlapped portion of each block is referred to as an “overlap portion”.
- the overlap amount M may be a fixed value determined in advance.
- an overlap adding circuit 710 and an overlap removing circuit 714 are configured in accordance with the overlap value M.
- the overlap addition circuit 710 and the overlap removal circuit 714 refer to the set value of the overlap amount M given from a higher-level circuit (not shown) such as a CPU (Central Processing Unit) and set it during operation. Also good.
- the overlap adding circuit 710 can be configured by a two-port memory, for example.
- the FFT circuit 711 performs FFT on the time domain input signal output from the overlap adding circuit 710 and overlapped with M data, converts the input signal into a frequency domain signal, and performs a filter operation circuit 712. Output to.
- the filter operation circuit 712 performs a filtering process on the frequency domain signal converted by the FFT circuit 711 and outputs the filtered signal to the IFFT circuit 713.
- the filter operation circuit 712 can be configured with a complex multiplier.
- the IFFT circuit 713 performs IFFT on the filtered frequency domain signal output from the filter arithmetic circuit 712, reconverts it into a time domain signal, and outputs it to the overlap removal circuit 714.
- the overlap removal circuit 714 removes a total of M data from both ends of each block made up of N data, which is a time domain signal reconverted by the IFFT circuit 713.
- the portion removed at this time is the aforementioned “removed portion”, and the number of data is equal to the overlap amount M.
- the overlap removal circuit 714 outputs “output portion” included in the overlap portion and data of the central portion of the non-overlap block as output data.
- FIG. 9 is an operation diagram showing an example of the operation of the digital filter circuit shown in FIG.
- the processing steps (1) to (5) correspond to the processing steps (1) to (5) in FIG. 9, respectively.
- the FFT circuit 711 performs FFT on a block made up of time domain signal data and converts it into a block made up of frequency domain signal data.
- the filter arithmetic circuit 712 performs filter processing on each frequency domain signal data constituting the block after FFT processing.
- H (k) represents a filter coefficient.
- the IFFT circuit 713 performs IFFT on the block composed of frequency domain signal data after the filter processing and reconverts the block composed of time domain signal data.
- the necessary overlap amount in the filter using the overlap processing is determined based on the impulse response length of the filter processing to be executed. Furthermore, the size of the FFT processing block needs to be larger than the required overlap amount. Therefore, the size of the FFT processing block is determined according to the impulse response length of the filter processing.
- Patent Document 7 There is also a technique for reducing the amount of hardware of a processing apparatus that performs FFT on a block whose size varies (see, for example, Patent Document 7).
- the orthogonal transform processor of Patent Document 7 is adapted to the length of the FFT vector (corresponding to “processing block”), determines the memory size, invalidates unnecessary circuit blocks, and operates the hardware in a time-sharing manner. I will let you.
- JP-A-8-137832 (page 3-5, FIG. 25) Japanese Patent Laid-Open No. 2001-56806 (5th page, FIG. 1) JP 2012-22500 A (page 5, FIG. 1) JP 2006-304192 A (page 4-5, FIG. 4) JP 2010-130355 A (page 3-6, FIG. 6) International Publication No. 2012/086262 (Page 3-4, Figure 1) Special table 2008-506191 (pages 11-12, FIGS. 11, 12)
- the size of the FFT processing block depends on the impulse response length of the filter processing. Therefore, as the impulse response length increases, the required overlap amount and the FFT processing block also increase. As a result, there is a problem that the circuit scale and power consumption required for processing increase.
- the orthogonal transform processor of Patent Document 7 determines the memory size, invalidates unnecessary circuit blocks, and operates hardware in a time division manner, but rearrangement processing in the FFT / IFFT processing itself is necessary. .
- the rearrangement process requires a memory having a capacity sufficient to store all the processing block data. Therefore, when the impulse response length of the filter processing is large and the size of the processing block is large, a large-scale memory is required, and there is a problem that the circuit scale and power consumption required for the processing increase.
- An object of the present invention is to provide a digital filter device, a digital filter processing method, and a storage medium storing a digital filter program that can reduce power consumption when FFT and frequency domain filter processing are used together. To do.
- the digital filter device of the present invention includes a first input block including a first input block including continuous (N ⁇ M) time domain input data (N is a positive integer and M is a positive integer smaller than N).
- An overlap adding means for adding the last continuous data of the second input block including the input data in the N time domain immediately before N as the overlap amount to generate an overlap block;
- Fourier transform means for transforming each of the overlap block and the second input block into a first frequency domain block and a second frequency domain block in the frequency domain by a fast Fourier transform process; a first frequency domain block; Filter each of the two frequency domain blocks to generate a first post-processing block and a second post-processing block Inverse Fourier transform that converts the filter operation means and each of the first processed block and the second processed block into a first time domain block and a second time domain block in the time domain by inverse fast Fourier transform processing.
- k at the front end of the time axis of the first time-domain block (k is greater than M)
- Mk data at the rear end of the time axis of the second time domain block are removed as removal partial data, and overlap removal means for generating output data;
- the removed partial data of the time domain block is compared with the output partial data other than the removed partial data in the overlapped portion of the second time domain block.
- Detecting a distortion amount of data included in Rappu portion generates, characterized in that it comprises overlapping error detection means for controlling the amount of overlap on the basis of the distortion amount.
- the digital filter processing method of the present invention provides a first input block including first (N ⁇ M) time domain input data (N is a positive integer and M is a positive integer smaller than N).
- An overlap block is generated by adding the last continuous data of the second input block including the continuous N time-domain input data immediately before the block by M as the overlap amount,
- Each of the second input blocks is converted into a first frequency domain block and a second frequency domain block in the frequency domain by fast Fourier transform processing, and each of the first frequency domain block and the second frequency domain block is converted.
- Filter processing is performed on the first post-processing block and the second post-processing block to generate the first post-processing block and the second post-processing block.
- k data (k is a positive integer smaller than M) at the front end of the time axis of the first time domain block and (M at the rear end of the time axis of the second time domain block) -K)
- the output data is generated by removing the data as the removal part data, and the data other than the removal part data of the removal part data of the first time domain block and the overlap part of the second time domain block Compared with the output part data, the amount of distortion generated by the data contained in the overlap part is detected, and the overlap amount is controlled based on the distortion amount To.
- the digital filter program stored in the storage medium of the present invention is a computer that includes a digital filter device, and includes (NM) continuous time domain input data (N is a positive integer, M is a positive integer smaller than N) ) Including the input data of the second input block including the input data in the N time regions immediately before the first input block in the first input block including And an overlap adding means for generating an overlap block, and each of the overlap block and the second input block into a first frequency domain block and a second frequency domain block in the frequency domain by fast Fourier transform processing.
- NM continuous time domain input data
- Overlap removal means for removing the data as removal partial data to generate output data, removal partial data of the first time domain block, and offset of the second time domain block.
- Overlap error detection means for detecting the amount of distortion generated by the data included in the overlap portion by comparing with output portion data other than the removal portion data in the burlap portion, and controlling the overlap amount based on the amount of distortion And function as the above.
- power consumption can be reduced when FFT and filter processing in the frequency domain are used together.
- FIG. 1 is a block diagram illustrating a configuration example of a digital filter circuit 200 according to an embodiment of the present invention.
- the digital filter circuit 200 performs filter processing such as FDE by the overlap method.
- the digital filter circuit 200 includes an overlap addition circuit 210, an FFT circuit 211, a filter operation circuit 212, an IFFT circuit 213, an overlap removal circuit 214, and an overlap error detection unit 215.
- the overlap adding circuit 210 sequentially generates an input block composed of N pieces of continuous data (N is a positive integer) from the input data which is an input signal in the time domain, and outputs the input block to the FFT circuit 211. At this time, the overlap adding circuit 210 overlaps each input block with the last M pieces of data (M is a positive integer) in the immediately preceding block. “Overlap” means that the predetermined X data at the beginning of each input block (X is a positive integer) is the same data as the last X data of the immediately preceding block, and X is duplicated in two blocks It means that the data of is included.
- the overlap adding circuit 210 generates an “overlap block” composed of consecutive N pieces of data including M pieces of overlapped data. Note that the overlap adding circuit 210 can be configured by a two-port memory, for example.
- the FFT circuit 211 performs N-point fast Fourier transform (FFT) on the overlap block output from the overlap adding circuit 210 to convert it into a frequency domain signal. Then, the FFT circuit 211 outputs a “frequency domain block” made up of N frequency domain data to the filter arithmetic circuit 212.
- FFT N-point fast Fourier transform
- the filter operation circuit 212 performs filter processing on the frequency domain block output from the FFT circuit 211, and outputs “processed block” to the IFFT circuit 213.
- the filter operation circuit 212 can be configured by a complex multiplier.
- the IFFT circuit 213 performs N-point inverse fast Fourier transform (IFFT) on the processed block output from the filter arithmetic circuit 212 and reconverts it into a time domain signal. Then, IFFT circuit 213 outputs a “time domain block” made up of N time domain data to overlap removal circuit 214.
- IFFT inverse fast Fourier transform
- the overlap removal circuit 214 removes a total of M “removed partial data” from both ends of the time axis of each time domain block output from the IFFT circuit 213. Then, the overlap removal circuit 214 extracts only the “output portion data” and the non-overlapping center portion of the overlap portion of the time domain block, and outputs them as “output data”.
- the overlap amount M is set to a predetermined value in advance. As will be described later, the overlap amount M is updated to an appropriate value by the overlap amount determination unit 222.
- the overlap addition circuit 210 and the overlap removal circuit 214 respectively add or remove overlap according to the overlap amount M at that time.
- the overlap amount M is smaller than the FFT block size N.
- the overlap error detection unit 215 compares the values of the removal portion data that is finally removed and the output portion data that is output without being removed, in the overlap portion of two consecutive FFT blocks. Detects the amount of distortion at the lap. The reason why the amount of distortion in the overlap portion is detected by this comparison is that the data in the output portion is a normal value that does not cause distortion, and the data in the removal portion may cause distortion.
- the overlap amount determination unit 222 increases the overlap amount M when the detected distortion amount is larger than a predetermined specified value.
- the overlap amount determination unit 222 decreases the overlap amount M when the detected distortion amount is smaller than a predetermined specified value.
- the overlap amount determination unit 222 outputs a control signal 216 that instructs to increase or decrease the overlap amount to the overlap addition circuit 210 and the overlap removal circuit 214.
- FIG. 2 is a block diagram showing a configuration example of the FFT circuit 211 in the embodiment of the present invention.
- the FFT circuit 211 processes the 64-point FFT decomposed into two-stage butterfly processing with a radix of 8 in accordance with the data flow 500 shown in FIG.
- the FFT circuit 211 performs 64-point FFT processing in parallel with 8 data.
- the FFT circuit 211 receives time-domain data x (n), generates and outputs a frequency-domain signal X (k) subjected to Fourier transform by FFT processing.
- a total of 64 pieces of data are input as input data x (n) in the order shown in FIG.
- the numbers from 0 to 63 shown as the contents of the table of FIG. 3 mean the subscript n of x (n).
- 8 data of X (0), X (1),..., X (7) constituting the data set P1 are output in the first cycle.
- 8 data of X (8), X (9),..., X (15) constituting the data set P2 are output.
- data constituting the data sets P3 to P8 are output from the third cycle to the eighth cycle.
- the FFT circuit 211 includes a first data rearrangement processing unit 11, a first butterfly calculation processing unit 21, a second data rearrangement processing unit 12, a twist multiplication processing unit 31, a second butterfly calculation processing unit 22, and A third data rearrangement processing unit 13 is provided.
- the FFT circuit 211 performs a first data rearrangement process, a first butterfly operation process, a second data rearrangement process, a twist multiplication process, a second butterfly operation process, and a third data rearrangement process. Line processing.
- the first data rearrangement processing unit 11 and the second data rearrangement processing unit 12 are buffer circuits for data rearrangement.
- the first data rearrangement processing unit 11 and the second data rearrangement processing unit 12 respectively have data dependence on the FFT processing algorithm before and after the first butterfly computation processing unit 21. Based on the data sequence rearrangement.
- the third data rearrangement processing unit 13 is a buffer circuit for data rearrangement. That is, the third data rearrangement processing unit 13 rearranges the data sequence after the second butterfly calculation processing unit 22 based on the data dependency on the FFT processing algorithm.
- the first data rearrangement processing unit 11 inputs the “sequential order” shown in FIG. 3, which is the input order of the input data x (n), to the first butterfly calculation processing unit 21.
- the data is rearranged in the “bit reverse order” shown in FIG.
- the bit reverse order shown in FIG. 4 corresponds to the input data set to the radix-8 butterfly processing 502 in the first stage in the data flow diagram shown in FIG. Specifically, in the first cycle, 8 data of x (0), x (8),..., X (56) constituting the data set P1 are input. Then, in the second cycle, 8 data of x (1), x (9),..., X (57) constituting the data set P2 are input. Thereafter, data constituting the data sets P3 to P8 is input in the same manner from the third cycle to the eighth cycle.
- “sequential order” and “bit reverse order” will be specifically described.
- “Sequential order” refers to the order of the eight data sets P1, P2, P3, P4, P5, P6, P7, and P8 shown in FIG.
- (i) ps (i) 8 (s-1) + i It is.
- Each data set is arranged in the order of P1, P2, P3, P4, P5, P6, P7, and P8 corresponding to the progress of the processing cycle. That is, the sequential order is created by creating s data sets in which i ⁇ s pieces of data are arranged i in order of data from the top data, and the data sets are arranged in a cycle order.
- bit reverse order refers to the order of the eight data sets Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 shown in FIG.
- Each data set is arranged in the order of Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 corresponding to the progress of the processing cycle.
- the bit reverse order is a sequence in which i ⁇ s pieces of data input in sequential order are arranged in s order from the top data in order of cycles, and i pieces of data in the same cycle are arranged in order of data as one set. It is.
- each data set in the bit reverse order is uniquely determined if each sequential order is set.
- Qs (i) and Pi (s) have a relationship in which the order of the cycle progress and the order of the data position are exchanged for the data constituting each data set. Therefore, when data input in the bit reverse order is rearranged according to the bit reverse order, the sequential order is obtained.
- Each row ps (i) in FIG. 3 and eight rows qs (i) in FIG. 4 indicate data input to the i-th data in the next stage.
- Eight numbers included in each data set are identification information for specifying one of the points of the FFT, specifically, the value of the subscript n of x (n).
- each sequential data set may be created by arranging data in order according to the number of FFT points, the number of cycles, and the number of data to be processed in parallel as described above. Then, as described above, each data set in the bit reverse order may be created by switching the order of the data input in the sequential order with respect to the progress of the cycle and the order of the data position.
- the first butterfly calculation processing unit 21 is a butterfly circuit that processes the first butterfly calculation process 502 (first butterfly calculation process) of the radix-8 butterfly calculation process performed twice in the data flow 500 of FIG. is there.
- the second data rearrangement processing unit 12 is shown in FIG. 4 in order to input the data y (n) output from the first butterfly calculation processing unit 21 in sequential order to the second butterfly calculation processing unit 22. Rearrange in bit reverse order.
- the twist multiplication processing unit 31 is a circuit that processes complex rotation on the complex plane in the FFT operation after the first butterfly operation processing, and corresponds to the twist multiplication processing 504 in the data flow 500 of FIG. In the twist multiplication process, data is not rearranged.
- the second butterfly computation processing unit 22 is a butterfly circuit that processes the second radix-8 butterfly process 503 in the data flow diagram of FIG.
- the third data rearrangement processing unit 13 rearranges the data X (k) output by the second butterfly computation processing unit 22 in the bit reverse order in the sequential order shown in FIG.
- the data rearrangement processing unit temporarily stores the input data, and controls the selection and output of the stored data, so that the sequential order shown in FIG. 2, the bit reverse order shown in FIG. 3, and the sequential order shown in FIG. Data rearrangement processing according to each order is realized. Below, the specific example of a data rearrangement process part is shown.
- the first data rearrangement processing unit 11, the second data rearrangement processing unit 12, and the third data rearrangement processing unit 13 can be realized by, for example, the data rearrangement processing unit 100 illustrated in FIG. .
- the data rearrangement processing unit 100 inputs data sets D1 to D8 consisting of eight data input as the input information 103 in the first-in first-out first-in first-out buffer (FIFO buffer). Write and store in storage locations 101a-101h. Specifically, data sets D1 to D8 are stored in the data storage positions 101a to 101h, respectively.
- FIFO buffer first-in first-out first-in first-out buffer
- the data rearrangement processing unit 100 outputs the stored data in the first-out order in the FIFO buffer. Specifically, the data rearrangement processing unit 100 reads eight pieces of data from each of the data reading positions 102 a to 102 h to form one data set, and outputs the eight data sets D 1 ′ to D 8 ′ as output information 104. To do. As described above, the data sets D1 'to D8' are obtained by rearranging the data included in the data sets D1 to D8 arranged in the cycle order in the order of the data positions.
- the FFT circuit 211 performs the sequential order shown in FIG. Three reordering processes according to the bit reverse order shown in FIG. 3 and the sequential order shown in FIG. 4 are required. This is because the FFT circuit 211 performs 64-point FFT processing in parallel with 8 data, so that 8 cycles are required for the FFT processing, and data must be rearranged across the cycles.
- the IFFT circuit 213 can also be realized with the same configuration as the FFT circuit 211.
- FIG. 6 is a block diagram illustrating a configuration example of the overlap error detection unit 215 according to the embodiment of the present invention.
- the overlap error detection unit 215 includes a first error comparison unit 221a, a second error comparison unit 221b, and an overlap amount determination unit 222.
- the overlap error detection unit 215 compares the removal data and the overlap output data included in each of the two consecutive FFT blocks, the FFT block FB (i) and the FFT block FB (i + 1), and the result The overlap amount M is determined based on the above.
- the detailed operation of the overlap error detection unit 215 is as follows.
- the first error comparison unit 221a detects and detects an error in the removed portion data of FB (i) by comparing the value of the removed portion data of FB (i) with the value of the output portion data of FB (i + 1).
- the error is output to the overlap amount determination unit 222.
- the second error comparison unit 221b detects an error in the removed partial data of FB (i + 1) by comparing the value of the output partial data of FB (i) and the value of the removed partial data of FB (i + 1). The detected error is output to the overlap amount determination unit 222.
- the overlap amount determination unit 222 includes the error of the removal portion data of FB (i) input from the first error comparison unit 221a and the removal portion data of FB (i + 1) input from the second error comparison unit 221b. The necessary overlap amount is determined on the basis of the error. Then, the overlap amount determination unit 222 outputs a control signal 216 that instructs to increase or decrease the overlap amount to the overlap addition circuit 210 and the overlap removal circuit 214. (Operation of the embodiment)
- the overlap error detection unit 215 detects the distortion amount of the overlap portion by comparing the value of the removal portion data and the value of the output portion data in the overlap portion of two consecutive FFT blocks. The reason why the amount of distortion in the overlap portion is detected by this comparison is that the data in the output portion is a normal value that does not cause distortion, and the data in the removal portion may cause distortion.
- the overlap error detection unit 215 increases the overlap amount M when the detected distortion amount is larger than a predetermined specified value.
- the overlap amount determination unit 215 decreases the overlap amount M when the detected distortion amount is smaller than a predetermined specified value.
- the overlap error detection unit 215 outputs a control signal 216 that instructs to increase or decrease the overlap amount to the overlap addition circuit 210 and the overlap removal circuit 214.
- the overlap addition circuit 210 and the overlap removal circuit 214 decrease the overlap amount M when the control signal 216 output from the overlap amount determination unit 215 instructs to decrease the overlap amount.
- the overlap addition circuit 210 and the overlap removal circuit 214 increase the overlap amount M when the control signal 216 instructs to increase the overlap amount.
- the overlap adding circuit 210 and the overlap removing circuit 214 respectively add and remove overlap according to the overlap amount M (effect of the embodiment). In the vicinity of both ends of the overlap portion in the FFT-processed block, data that causes distortion of the signal is included. The amount of distortion is large when the actual overlap amount M is small and small when the overlap amount M is large with respect to the necessary overlap amount. Further, since the total processing amount increases as the overlap amount M increases, the power consumption of the digital filter circuit 200 also increases.
- the digital filter circuit 200 detects the amount of distortion generated in the overlap portion by comparing the data of the overlap portion between two consecutive FFT blocks.
- the digital filter circuit 200 increases the overlap amount M when the detected distortion amount is larger than a predetermined specified value, and the overlap amount M when the detected distortion amount is small. Decrease. That is, the digital filter circuit 200 adaptively controls the overlap amount M in accordance with the detected distortion of the overlap portion.
- the amount of distortion generated by the output data of the digital filter circuit 200 can be maintained at an appropriate amount.
- the filter processing is performed with the minimum overlap amount necessary to maintain an appropriate amount of distortion, so that the power consumption required for the filter processing can be reduced.
- the overlap amount determination unit 222 includes two error comparison units in order to detect an error in each of the removed portion data of the block before and after the two consecutive FFT blocks, Determine the amount of overlap.
- the overlap amount determination unit 222 includes only an error comparison unit that detects an error of the removal portion data of either the previous block or the subsequent block, and the necessary overlap amount is calculated only from the output of the error comparison unit. You may decide.
- each process such as FFT, IFFT, and filter processing is processed by components such as individual circuits.
- the processing of each embodiment may be executed by software using a computer provided in a predetermined apparatus, for example, a DSP (Digital Signal Processor). That is, a computer program for performing each process is read and executed by a DSP (not shown).
- DSP Digital Signal Processor
- data rearrangement processing may be performed using a program.
- data rearrangement processing may be performed by using a DSP and a memory to control writing of data to the memory and reading of data from the memory by a program.
- the FFT processing may be performed using a program.
- the above processing program is stored in a non-transitory medium such as a ROM (Read Only Memory), a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, an optical disk, a magnetic disk, a magneto-optical disk, or the like. Also good.
- a non-transitory medium such as a ROM (Read Only Memory), a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, an optical disk, a magnetic disk, a magneto-optical disk, or the like. Also good.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Mathematical Analysis (AREA)
- Mathematical Optimization (AREA)
- Pure & Applied Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- Computational Mathematics (AREA)
- Data Mining & Analysis (AREA)
- Algebra (AREA)
- Quality & Reliability (AREA)
- Databases & Information Systems (AREA)
- Software Systems (AREA)
- Discrete Mathematics (AREA)
- Computing Systems (AREA)
- Computer Hardware Design (AREA)
- Complex Calculations (AREA)
Abstract
Description
このとき除去される部分が前述の「除去部分」であり、そのデータの個数はオーバーラップ量Mに等しい。そして、オーバーラップ除去回路714は、オーバーラップ部分に含まれる「出力部分」とオーバーラップしていないブロックの中央部分のデータとを出力データとして出力する。
オーバーラップ付加回路710は、時間領域の入力信号である入力データから、N個のデータ(Nは正整数)からなるブロックを順次生成する。このとき、オーバーラップ付加回路710は、直前のブロックとM個のデータだけ重複(オーバーラップ)させる。
入力データを
x(i) (i=0,1,・・・)
としたとき、Nデータのブロックは
x(j) (j=m(N-M)-N~m(N-M)-1,mは正整数)
で表される。ここで、NはFFTブロックサイズ、Mはオーバーラップ量である。
FFT回路711は、時間領域の信号データからなるブロックに対して、FFTを行い、周波数領域の信号データからなるブロックに変換する。
N個の時間領域の信号データからなるブロックをあらためて
x(n) (n=0,1,・・・,N-1)
とすると、FFT処理後の周波数領域のブロックは
X(k) (k=0,1,・・・,N-1)
で与えられる。
フィルタ演算回路712は、FFT処理後のブロックを構成する周波数領域の各信号データに対して、フィルタ処理を行う。
フィルタ処理前のブロックX(k)に対するフィルタ処理後のブロックは
X'(k)=H(k)・X(k) (k=0,1,・・・,N-1)
で与えられる。ここで、H(k)はフィルタ係数を示す。
IFFT回路713は、フィルタ処理後の周波数領域の信号データからなるブロックに対して、IFFTを行い、時間領域の信号データからなるブロックに再変換する。
IFFT処理前のブロックX'(k)に対するIFFT処理後のブロックは、
y(n) (n=0,1,・・・,N-1)
で与えられる。
オーバーラップ除去回路714は、IFFT処理後のN個の信号データからなるブロックy(n)から、ブロック先頭及び末端からそれぞれM/2個のオーバーラップ分のデータ、すなわち除去部分のデータを除いた中央部分を切り出す。
これにより、除去部分のデータが除去され、ブロックy(n)のオーバーラップ部分に含まれる出力部分と、オーバーラップしていない中央部とからなる(N-M)個の信号データ系列
y'(j) (j=M/2~(N-1)-M/2)
が生成される。
(発明の目的)
本発明は、FFTと周波数領域におけるフィルタ処理を併用する場合に、消費電力を削減することができるデジタルフィルタ装置、デジタルフィルタ処理方法及びデジタルフィルタプログラムが記憶された記憶媒体を提供することを目的とする。
次に本発明の実施の形態について図面を参照して詳細に説明する。図1は、本発明の実施形態におけるデジタルフィルタ回路200の構成例を示すブロック図である。
ps(i)=8(s-1)+i
である。そして、各データ組は、処理のサイクルの進行に対応して、P1、P2、P3、P4、P5、P6、P7、P8の順に並べられている。つまり、逐次順序とは、i×s個のデータを、先頭のデータからi個ずつデータ順に並べたデータ組をs個作成し、そのデータ組をサイクル順に並べたものである。
qs(i)=(s-1)+8i
である。そして、各データ組は、処理のサイクルの進行に対応して、Q1、Q2、Q3、Q4、Q5、Q6、Q7、Q8の順に並べられている。つまり、ビットリバース順序とは、逐次順序で入力されたi×s個のデータを、先頭のデータからs個ずつサイクル順に並べ、同じサイクルのi個のデータを1つの組としてデータ順に並べたものである。
Qs(i)=Pi(s)
である。このように、Qs(i)とPi(s)とは、各データ組を構成するデータについての、サイクルの進行に対する順序とデータ位置に対する順序が入れ替えられた関係にある。従って、ビットリバース順序で入力されたデータを、ビットリバース順序に従って並べ替えると、逐次順序になる。
(実施形態の動作)
オーバーラップ誤差検出部215は、連続する2つのFFTブロックのオーバーラップ部分において、除去部分データの値と出力部分データの値とを互いに比較することで、オーバーラップ部分の歪み量を検出する。この比較によってオーバーラップ部分の歪み量が検出される理由は、出力部分のデータは歪みを発生させる場合がない正常な値であり、除去部分のデータは歪みを発生させる場合があるからである。
(実施形態の効果)
FFT処理されたブロックにおけるオーバーラップ部分の両端付近には、信号に歪みを発生させるデータが含まれる。そして、その歪みの量は、必要なオーバーラップ量に対して、実際のオーバーラップ量Mが小さい場合には大きく、オーバーラップ量Mが大きい場合には小さい。また、オーバーラップ量Mが大きいほど、処理量の合計が増加するので、デジタルフィルタ回路200の消費電力も増加する。
12 第2のデータ並べ替え処理部
13 第3のデータ並べ替え処理部
21 第1のバタフライ演算処理部
22 第2のバタフライ演算処理部
31 ひねり乗算処理部
100 データ並べ替え処理部
101a~101h データ記憶位置
102a~102h データ読み出し位置
103 入力情報
104 出力情報
200 デジタルフィルタ回路
210 オーバーラップ付加回路
211 FFT回路
212 フィルタ演算回路
213 IFFT回路
214 オーバーラップ除去回路
215 オーバーラップ誤差検出部
216 制御信号
221a 第1の誤差比較部
221b 第2の誤差比較部
222 オーバーラップ量決定部
500 データフロー
501 データ並べ替え処理
502、503 バタフライ演算処理
504 ひねり乗算処理
505a~505h 部分データフロー
700 デジタルフィルタ回路
710 オーバーラップ付加回路
711 FFT回路
712 フィルタ演算回路
713 IFFT回路
714 オーバーラップ除去回路
Claims (6)
- 連続する(N-M)個の時間領域の入力データ(Nは正整数、MはNより小さい正整数)を含む第1の入力ブロックに、前記第1の入力ブロックの直前の連続するN個の時間領域の入力データを含む第2の入力ブロックの最後の連続するデータをオーバーラップ量であるM個だけ付加し、オーバーラップブロックを生成するオーバーラップ付加手段と、
前記オーバーラップブロック及び前記第2の入力ブロックのそれぞれを、高速フーリエ変換処理により周波数領域の第1の周波数領域ブロック及び第2の周波数領域ブロックに変換するフーリエ変換手段と、
前記第1の周波数領域ブロック及び前記第2の周波数領域ブロックのそれぞれに対してフィルタ処理を行い、第1の処理後ブロック及び第2の処理後ブロックを生成するフィルタ演算手段と、
前記第1の処理後ブロック及び前記第2の処理後ブロックのそれぞれを、逆高速フーリエ変換処理により時間領域の第1の時間領域ブロック及び第2の時間領域ブロックに変換する逆フーリエ変換手段と、
前記第1の時間領域ブロック及び前記第2の時間領域ブロックのそれぞれが時間的にオーバーラップするオーバーラップ部分のうち、前記第1の時間領域ブロックの時間軸の前端のk個(kはMより小さい正整数)のデータ及び前記第2の時間領域ブロックの時間軸の後端の(M-k)個のデータを除去部分データとして除去し、出力データを生成するオーバーラップ除去手段と、
前記第1の時間領域ブロックの前記除去部分データと、前記第2の時間領域ブロックの前記オーバーラップ部分のうちの前記除去部分データ以外の出力部分データとを比較して前記オーバーラップ部分に含まれるデータが発生させる歪み量を検出し、前記歪み量に基づいて前記オーバーラップ量を制御するオーバーラップ誤差検出手段と、
を備えることを特徴とするデジタルフィルタ装置。 - 前記オーバーラップ誤差検出手段は、
前記検出した歪み量が規定値よりも大きい場合には、前記オーバーラップ量を増加させ、
前記検出した歪み量が規定値よりも小さい場合には、前記オーバーラップ量を減少させる
ことを特徴とする請求項1に記載のデジタルフィルタ装置。 - 前記オーバーラップ誤差検出手段は、
前記第1の時間領域ブロックの前記除去部分データと、前記第2の時間領域ブロックの前記出力部分データとを比較し、前記第1の時間領域ブロックの前記歪み量を検出する第1の誤差比較部と、
前記第1の誤差比較部によって検出された歪み量に基づいて前記オーバーラップ量を決定するオーバーラップ量決定部と、を含む
ことを特徴とする請求項1又は2に記載のデジタルフィルタ装置。 - 前記オーバーラップ誤差検出手段は、
前記第2の時間領域ブロックの前記除去部分データと、前記第1の時間領域ブロックの前記出力部分データとを比較し、前記第2の時間領域ブロックの前記歪み量を検出する第2の誤差比較部を含み、
前記オーバーラップ量決定部は、前記第2の誤差比較部によって検出された歪み量に基づいて前記オーバーラップ量を決定する
ことを特徴とする請求項3に記載のデジタルフィルタ装置。 - 連続する(N-M)個の時間領域の入力データ(Nは正整数、MはNより小さい正整数)を含む第1の入力ブロックに、前記第1の入力ブロックの直前の連続するN個の時間領域の入力データを含む第2の入力ブロックの最後の連続するデータをオーバーラップ量であるM個だけ付加してオーバーラップブロックを生成し、
前記オーバーラップブロック及び前記第2の入力ブロックのそれぞれを、高速フーリエ変換処理により周波数領域の第1の周波数領域ブロック及び第2の周波数領域ブロックに変換し、
前記第1の周波数領域ブロック及び前記第2の周波数領域ブロックのそれぞれに対してフィルタ処理を行って第1の処理後ブロック及び第2の処理後ブロックを生成し、
前記第1の処理後ブロック及び前記第2の処理後ブロックのそれぞれを、逆高速フーリエ変換処理により時間領域の第1の時間領域ブロック及び第2の時間領域ブロックに変換し、
前記第1の時間領域ブロック及び前記第2の時間領域ブロックのそれぞれが時間的にオーバーラップするオーバーラップ部分のうち、前記第1の時間領域ブロックの時間軸の前端のk個(kはMより小さい正整数)のデータ及び前記第2の時間領域ブロックの時間軸の後端の(M-k)個のデータを除去部分データとして除去して出力データを生成し、
前記第1の時間領域ブロックの前記除去部分データと、前記第2の時間領域ブロックの前記オーバーラップ部分のうちの前記除去部分データ以外の出力部分データとを比較して前記オーバーラップ部分に含まれるデータが発生させる歪み量を検出し、前記歪み量に基づいて前記オーバーラップ量を制御する
ことを特徴とするデジタルフィルタ処理方法。 - デジタルフィルタ装置が備えるコンピュータを、
連続する(N-M)個の時間領域の入力データ(Nは正整数、MはNより小さい正整数)を含む第1の入力ブロックに、前記第1の入力ブロックの直前の連続するN個の時間領域の入力データを含む第2の入力ブロックの最後の連続するデータをオーバーラップ量であるM個だけ付加し、オーバーラップブロックを生成するオーバーラップ付加手段と、
前記オーバーラップブロック及び前記第2の入力ブロックのそれぞれを、高速フーリエ変換処理により周波数領域の第1の周波数領域ブロック及び第2の周波数領域ブロックに変換するフーリエ変換手段と、
前記第1の周波数領域ブロック及び前記第2の周波数領域ブロックのそれぞれに対してフィルタ処理を行い、第1の処理後ブロック及び第2の処理後ブロックを生成するフィルタ演算手段と、
前記第1の処理後ブロック及び前記第2の処理後ブロックのそれぞれを、逆高速フーリエ変換処理により時間領域の第1の時間領域ブロック及び第2の時間領域ブロックに変換する逆フーリエ変換手段と、
前記第1の時間領域ブロック及び前記第2の時間領域ブロックのそれぞれが時間的にオーバーラップするオーバーラップ部分のうち、前記第1の時間領域ブロックの時間軸の前端のk個(kはMより小さい正整数)のデータ及び前記第2の時間領域ブロックの時間軸の後端の(M-k)個のデータを除去部分データとして除去し、出力データを生成するオーバーラップ除去手段と、
前記第1の時間領域ブロックの前記除去部分データと、前記第2の時間領域ブロックの前記オーバーラップ部分のうちの前記除去部分データ以外の出力部分データとを比較して前記オーバーラップ部分に含まれるデータが発生させる歪み量を検出し、前記歪み量に基づいて前記オーバーラップ量を制御するオーバーラップ誤差検出手段と、
として機能させるためのデジタルフィルタプログラムが記憶された記憶媒体。
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15/103,112 US9880975B2 (en) | 2013-12-13 | 2014-11-19 | Digital filter device, digital filter processing method, and storage medium having digital filter program stored thereon |
JP2015552301A JP6489021B2 (ja) | 2013-12-13 | 2014-11-19 | デジタルフィルタ装置、デジタルフィルタ処理方法及びデジタルフィルタプログラム |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2013-258272 | 2013-12-13 | ||
JP2013258272 | 2013-12-13 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2015087495A1 true WO2015087495A1 (ja) | 2015-06-18 |
Family
ID=53370826
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2014/005802 WO2015087495A1 (ja) | 2013-12-13 | 2014-11-19 | デジタルフィルタ装置、デジタルフィルタ処理方法及びデジタルフィルタプログラムが記憶された記憶媒体 |
Country Status (3)
Country | Link |
---|---|
US (1) | US9880975B2 (ja) |
JP (1) | JP6489021B2 (ja) |
WO (1) | WO2015087495A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2017094824A1 (ja) * | 2015-12-02 | 2017-06-08 | 日本電気株式会社 | ディジタルフィルタ、フィルタ処理方法及び記録媒体 |
WO2021117140A1 (ja) * | 2019-12-10 | 2021-06-17 | 三菱電機株式会社 | フィルタ回路、信号処理方法、制御回路およびプログラム記憶媒体 |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9880975B2 (en) * | 2013-12-13 | 2018-01-30 | Nec Corporation | Digital filter device, digital filter processing method, and storage medium having digital filter program stored thereon |
CN107113257B (zh) * | 2015-01-30 | 2020-07-10 | 南通数动互联科技有限公司 | 数据处理的方法和装置 |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2012086262A1 (ja) * | 2010-12-21 | 2012-06-28 | 日本電気株式会社 | デジタルフィルタ回路およびデジタルフィルタ制御方法 |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3219613B2 (ja) | 1994-11-14 | 2001-10-15 | 三菱重工業株式会社 | アンモニア分解触媒及びアンモニアの分解除去方法 |
JP2001056806A (ja) | 1999-06-10 | 2001-02-27 | Matsushita Electric Ind Co Ltd | 高速フーリエ変換装置 |
US7502816B2 (en) * | 2003-07-31 | 2009-03-10 | Panasonic Corporation | Signal-processing apparatus and method |
WO2006014528A1 (en) | 2004-07-08 | 2006-02-09 | Asocs Ltd. | A method of and apparatus for implementing fast orthogonal transforms of variable size |
JP4737747B2 (ja) | 2005-04-25 | 2011-08-03 | パナソニック株式会社 | 無線通信装置および無線通信方法 |
JP2010130355A (ja) | 2008-11-27 | 2010-06-10 | Sharp Corp | 受信装置および受信方法 |
JP2011004264A (ja) * | 2009-06-19 | 2011-01-06 | Fujitsu Ltd | ディジタル信号処理装置およびディジタル信号処理方法 |
JP5549442B2 (ja) | 2010-07-14 | 2014-07-16 | 三菱電機株式会社 | Fft演算装置 |
JP5821584B2 (ja) * | 2011-12-02 | 2015-11-24 | 富士通株式会社 | 音声処理装置、音声処理方法及び音声処理プログラム |
US9934199B2 (en) * | 2013-07-23 | 2018-04-03 | Nec Corporation | Digital filter device, digital filtering method, and storage medium having digital filter program stored thereon |
US9880975B2 (en) * | 2013-12-13 | 2018-01-30 | Nec Corporation | Digital filter device, digital filter processing method, and storage medium having digital filter program stored thereon |
-
2014
- 2014-11-19 US US15/103,112 patent/US9880975B2/en active Active
- 2014-11-19 WO PCT/JP2014/005802 patent/WO2015087495A1/ja active Application Filing
- 2014-11-19 JP JP2015552301A patent/JP6489021B2/ja active Active
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2012086262A1 (ja) * | 2010-12-21 | 2012-06-28 | 日本電気株式会社 | デジタルフィルタ回路およびデジタルフィルタ制御方法 |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2017094824A1 (ja) * | 2015-12-02 | 2017-06-08 | 日本電気株式会社 | ディジタルフィルタ、フィルタ処理方法及び記録媒体 |
US10855255B2 (en) | 2015-12-02 | 2020-12-01 | Nec Corporation | Digital filter, filter processing method, and recording medium |
WO2021117140A1 (ja) * | 2019-12-10 | 2021-06-17 | 三菱電機株式会社 | フィルタ回路、信号処理方法、制御回路およびプログラム記憶媒体 |
Also Published As
Publication number | Publication date |
---|---|
US9880975B2 (en) | 2018-01-30 |
JP6489021B2 (ja) | 2019-03-27 |
US20160357705A1 (en) | 2016-12-08 |
JPWO2015087495A1 (ja) | 2017-03-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP6288089B2 (ja) | デジタルフィルタ装置、デジタルフィルタ処理方法及びデジタルフィルタプログラムが記憶された記憶媒体 | |
JP6489021B2 (ja) | デジタルフィルタ装置、デジタルフィルタ処理方法及びデジタルフィルタプログラム | |
JP5599874B2 (ja) | 信号処理方法ならびにデータ処理の方法および装置 | |
US9785614B2 (en) | Fast Fourier transform device, fast Fourier transform method, and recording medium storing fast Fourier transform program | |
JP6256348B2 (ja) | 高速フーリエ変換回路、高速フーリエ変換処理方法及び高速フーリエ変換処理プログラム | |
CN104349260A (zh) | 低功耗wola滤波器组及其综合阶段电路 | |
KR102376492B1 (ko) | 실수값을 입력으로 하는 고속푸리에 변환장치 및 방법 | |
JP6451647B2 (ja) | 高速フーリエ変換装置、高速フーリエ変換方法、及び高速フーリエ変換プログラム | |
JP6930607B2 (ja) | 信号処理装置、方法、プログラムと記録媒体 | |
CN102957993B (zh) | 低功耗wola滤波器组及其分析阶段电路 | |
JP6436087B2 (ja) | デジタルフィルタ装置、デジタルフィルタ処理方法およびプログラム | |
US10853445B2 (en) | Digital filter device, digital filtering method, and program recording medium | |
JP6977883B2 (ja) | 信号処理装置、方法、プログラム | |
US20230289397A1 (en) | Fast fourier transform device, digital filtering device, fast fourier transform method, and non-transitory computer-readable medium | |
JP6943283B2 (ja) | 高速フーリエ変換装置、データ並べ替え処理装置、高速フーリエ変換処理方法およびプログラム | |
US20220188014A1 (en) | Digital filter device, operation method for digital filter device, and non-transitory computer-readable medium storing program | |
WO2021193947A1 (ja) | デジタルフィルタ装置 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 14869277 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2015552301 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 15103112 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 14869277 Country of ref document: EP Kind code of ref document: A1 |