WO2003009081A2 - System, method and computer program to compute a fast fourier transform of data blocks - Google Patents
System, method and computer program to compute a fast fourier transform of data blocks Download PDFInfo
- Publication number
- WO2003009081A2 WO2003009081A2 PCT/IB2002/002849 IB0202849W WO03009081A2 WO 2003009081 A2 WO2003009081 A2 WO 2003009081A2 IB 0202849 W IB0202849 W IB 0202849W WO 03009081 A2 WO03009081 A2 WO 03009081A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- fast fourier
- fourier transform
- data
- strt
- fft
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
- H04L27/06—Demodulator circuits; Receiver circuits
-
- 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
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2649—Demodulators
- H04L27/265—Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators
- H04L27/2651—Modification of fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators for performance improvement
Definitions
- the present invention relates to a digital demodulator adapted to compute a Fast Fourier Transform using data blocks.
- the invention also relates to an associated Fast Fourier Transform processing method.
- Such a demodulator may be used, for example, in a terrestrial receiver.
- FFT processor dedicated to a Fast Fourier Transform computation commonly called FFT processor.
- FFT processor work on data blocks, said data also being called symbols. Therefore, as described in the project number DVbird WP1 - D01 entitled “First Receiver Architecture Ics specification " edited by the ACTS ('Advanced Communication Technologies & Services") in May 1996, a start signal is often generated to indicate a first data (D) of a new block. Said start signal is sent to the FFT processor.
- said signal generation requires: a counter (CPT) to count a number of data which have been input to the FFT processor (FFT-P) since a last start signal (S_STRT), in order to know when to start a new Fast Fourier Transform computation, and - some feedback information (S_ERR) to generate a start signal S_STRT.
- CPT counter
- FFT-P FFT processor
- S_STRT last start signal
- S_ERR feedback information
- Such a counter CPT is contained in a start generator dedicated module (M- STRT) and such feedback information S_ERR are output by a time error dedicated module (M-TMERR). If the number of input data has reached the number of data in a block, usually 2 kilo-octets or 8 kilo-octets, a start signal S_STRT can be sent to the FFT processor FFTJP. The start signal has to be synchronized with a first data D of a new block. Such synchronization is needed in order for the FFT processor FFT_P to save the data of the data block as soon as a first data is received.
- M- STRT start generator dedicated module
- M-TMERR time error dedicated module
- the feedback information S_ERR tells the start generator M-STRT how much additional data D it has to count before a new start signal is sent.
- DSP general purpose digital signal processor
- the FFT coprocessor counts the number of data D which has been input to make a FFT computation, and, on the other hand, the digital signal processor DSP also counts a number of data D to be input to the Fast Fourier Transform coprocessor before enabling the sending of a start signal S_STRT.
- such digital signal processor enables the start generator M_STRT so as to synchronize the emission of a start signal S STRT with a first data D of a data block.
- DSP digital signal processor
- a digital demodulator which comprises: a Fast Fourier Transform coprocessor comprising a start generator function adapted to send a start signal to a Fast Fourier Transform computation function, said start signal indicating a first data of a new data block, and - a digital signal processor comprising a time error function adapted to send feedback information to said Fast Fourier Transform coprocessor, said feedback information indicating for how much data the start generator function has to wait before a new start signal is sent.
- a method comprising the steps of: - sending a start signal to a Fast Fourier Transform computation function via a
- Fig. 1 illustrates some components of a digital demodulator as described in the prior art
- Fig. 2 is a graph of a Fast Fourier Transform algorithm used in a digital demodulator according to the invention
- Fig. 3 illustrated some components of the digital demodulator according to the invention
- Fig. 4 is a diagram of a Fast Fourier Transform method implemented in the digital demodulator of Fig. 3.
- the present invention relates to a digital demodulator DEM adapted to compute a Fast Fourier Transform using data blocks.
- a digital demodulator DEM is used for a demodulation of a digital television system, and more particularly for a demodulation in a terrestrial receiver.
- Such a receiver receives a signal, it receives it in the form of data blocks also called symbols packets.
- Such packets have fixed length.
- DVB-T « Digital Video Broadcasting Terrestrial »
- ETSI « European Telecommunications Standard Institute »
- the length of the packet is 2 Kilo- octets or 8 Kilo-octets.
- One step of the demodulation is to compute Fast Fourier Transforms on the data D of a packet.
- the computation of a Fast Fourier Transform is made thanks to an algorithm called the Cooley-Tukey algorithm of radix 2 whose corresponding graph is shown in Fig. 2.
- Such a graph comprises coefficients W.
- Final results R which are frequency data, are computed with input data D and said coefficients W.
- Said coefficients W are known and usually saved in a table of a memory MEM. Such a computation will not be explained here, as it is well known by the man skilled in the art.
- the digital demodulator DEM comprises: a Fast Fourier Transform coprocessor FFT_P comprising a start generator function F_STRT adapted to send a start signal S_STRT to a Fast Fourier Transform computation function F_FFT, said start signal indicating a first data D of a new data block, and a digital signal processor DSP comprising a time error function F_TMERR adapted to send feedback information DIST to said Fast Fourier Transform coprocessor FFT_P, said feedback information DIST indicating how much data D the start generator function F_STRT has to wait until the sending of a new start signal S_STRT.
- FFT_P comprising a start generator function F_STRT adapted to send a start signal S_STRT to a Fast Fourier Transform computation function F_FFT, said start signal indicating a first data D of a new data block
- a digital signal processor DSP comprising a time error function F_TMERR adapted to send feedback information DIST to said Fast Fourier Transform co
- the Fast Fourier Transform computation function F_FFT is adapted to compute a Fast Fourier Transform on data D of a data block.
- the Fast Fourier Transform coprocessor FFT_P also comprises an address generation function F_ADDR adapted to save said data D in particular addresses in the memory MEM of the Fast Fourier Transform coprocessor FFT_P, and adapted to count the input and saved data D with the counter CPT.
- the digital signal processor DSP downloads into the Fast Fourier Transform coprocessor FFTJP the parameters required for a Fast Fourier Transform computation.
- Those parameters are in particular: the size SZ of a data block, 2 Kilo-octets or 8 Kilo-octets, a guard interval GRD between the computation of two Fast Fourier Transforms FFT etc.
- Said guard interval GRD is used to avoid, in particular, a well-known phenomenon called mtersyrnbol interferencelSI phenomenon.
- Such an initialization step is made each time there is a deep change regarding the environment of the receiver.
- the size of a data block is preferably 8 Kilo-octets.
- the digital demodulator will compute a Fast Fourier Transform on these data as follows.
- the start generator function F STRT detects a first data D of a new data block, and then sends a start signal S_STRT to the Fast Fourier Transform computation function F_FFT.
- the address generation function F_ADDR counts the number of input data D with its counter CPT, and saves them in addresses of the memory MEM.
- the computation function F_FFT waits for all the data D of a block to be input. Then it computes a Fast Fourier Transform, using the Cooley-Tukey algorithm, on these data D with the information given by the digital signal processor DSP and thanks to the counter CPT of the address generation function F_ADDR.
- a fourth step 4 if there is an error S_ERR in the final results R, said error S_ERR is detected by the time error function F_TMERR of the digital signal processor DSP.
- the time error function F_TMERR determines feedback information, for example, a correction distance DIST evaluated in a number N of data D. For example, N is equal to 1 if the Fast Fourier Transform computation has begun one data too late.
- This correction distance DIST is then sent to the Fast Fourier Transform coprocessor FFT_P.
- the correction distance DIST enables to know how much additional data D we have to wait before finding a first data D of a new data block.
- this correction distance DIST enables to know for how much data D said Fast Fourier Transform coprocessor FFT_P, and more precisely, the signal generator function F_STRT has to wait before sending again a new start signal S_STRT, and thus before computing a new Fast Fourier Transform.
- the start generator function F_STRT detects a first data D of a new data block thanks to the counter CPT.
- the counter CPT has reached a value equal to a data block length plus a guard interval GRD and plus (when the Fast Fourier Transform computation has begun some data too late) or minus (when the Fast Fourier Transform computation has begun some data too early) the correction distance DIST, a new first data is received.
- the start generator F_STRT sends a start signal S_STRT to the Fast Fourier Transform computation function F_FFT etc ... until no more data D are received.
- one advantage of the present invention is that, when no error S_ERR is detected, the Fast Fourier Transform coprocessor FFTJP can work by itself without any interaction with said digital processor DSP. Moreover, in the method according to the invention, said coprocessor FFTJP does not wait for a start signal to be sent from said digital signal processor. Hence, said coprocessor FFT__P is independent of said digital processor DSP. Thus, in the meantime, said digital signal processor DSP can be addressed by other coprocessors.
- the digital signal processor DSP comprises deactivation means M_DES which are adapted to deactivate the start generator function F_STRT in the Fast Fourier Transform coprocessor FFT_P.
- the deactivation is done during the initialization step 0).
- the deactivation means can be a program implemented in said digital signal processor.
- Said hardware or software items can be implemented in several ways, such as by means of wired electronic circuits or by means of an integrated circuit that is suitably programmed.
- the integrated circuit can be contained in a computer or in a demodulator.
- the different means of demodulator according to the invention can be hardware or software items as stated above.
- the integrated circuit comprises a set of instructions.
- said set of instructions contained, for example, in a computer programming memory or in a demodulator memory may cause the computer or the demodulator to carry out the various steps of the Fast Fourier Transform processing method.
- the set of instructions may be loaded into the programming memory by reading a data carrier such as, for example, a disk.
- a service provider can also make the set of instructions available via a communication network such as, for example, the Internet.
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003514359A JP4232870B2 (en) | 2001-07-17 | 2002-07-05 | Digital demodulator for terrestrial receiver |
DE60238495T DE60238495D1 (en) | 2001-07-17 | 2002-07-05 | SYSTEM, METHOD AND COMPUTER PROGRAM FOR CALCULATING A FAST FOURIER TRANSFORMATION OF DATA BLOCKS |
KR10-2004-7000738A KR20040017314A (en) | 2001-07-17 | 2002-07-05 | Digital demodulator for terrestrial receiver |
EP02743573A EP1430375B1 (en) | 2001-07-17 | 2002-07-05 | System, method and computer program to compute a fast fourier transform of data blocks |
AT02743573T ATE490499T1 (en) | 2001-07-17 | 2002-07-05 | SYSTEM, METHOD AND COMPUTER PROGRAM FOR COMPUTING A FAST FOURIER TRANSFORMATION OF DATA BLOCKS |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP01401913.7 | 2001-07-17 | ||
EP01401913 | 2001-07-17 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2003009081A2 true WO2003009081A2 (en) | 2003-01-30 |
WO2003009081A3 WO2003009081A3 (en) | 2004-04-29 |
Family
ID=8182809
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IB2002/002849 WO2003009081A2 (en) | 2001-07-17 | 2002-07-05 | System, method and computer program to compute a fast fourier transform of data blocks |
Country Status (8)
Country | Link |
---|---|
US (1) | US7145965B2 (en) |
EP (1) | EP1430375B1 (en) |
JP (1) | JP4232870B2 (en) |
KR (1) | KR20040017314A (en) |
CN (1) | CN1262951C (en) |
AT (1) | ATE490499T1 (en) |
DE (1) | DE60238495D1 (en) |
WO (1) | WO2003009081A2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN1688104B (en) * | 2005-06-20 | 2010-11-10 | 北京中星微电子有限公司 | Digital signal processing method and apparatus |
US8738680B2 (en) | 2008-03-28 | 2014-05-27 | Qualcomm Incorporated | Reuse engine with task list for fast fourier transform and method of using the same |
NL1041689B1 (en) | 2016-01-25 | 2017-07-31 | Petrus Josephus Andreas Van Der Zanden Johannes | Acceleration unit for impact crusher. |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5774388A (en) * | 1993-08-11 | 1998-06-30 | France Telecom | Device for electronically calculating a fourier transform and method of minimizing the size of internal data paths within such a device |
EP0913778A1 (en) * | 1997-10-31 | 1999-05-06 | Integrated Silicon Systems Limited | A commutator circuit |
US6279022B1 (en) * | 1998-11-13 | 2001-08-21 | Integrated Telecom Express, Inc. | System and method for detecting symbol boundary in multi-carrier transmission systems |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4754449A (en) * | 1986-07-02 | 1988-06-28 | Hughes Aircraft Company | Wide bandwidth device for demodulating frequency division multiplexed signals |
US6334219B1 (en) * | 1994-09-26 | 2001-12-25 | Adc Telecommunications Inc. | Channel selection for a hybrid fiber coax network |
JP2955285B1 (en) * | 1998-09-30 | 1999-10-04 | 松下電器産業株式会社 | Digital audio receiver |
US6167526A (en) * | 1998-12-29 | 2000-12-26 | Adaptec, Inc. | Method and apparatus for synchronizing a decoder circuit with a phase-encoded data signal in a data storage device |
US6898235B1 (en) * | 1999-12-10 | 2005-05-24 | Argon St Incorporated | Wideband communication intercept and direction finding device using hyperchannelization |
-
2002
- 2002-07-05 CN CNB028029054A patent/CN1262951C/en not_active Expired - Fee Related
- 2002-07-05 DE DE60238495T patent/DE60238495D1/en not_active Expired - Lifetime
- 2002-07-05 AT AT02743573T patent/ATE490499T1/en not_active IP Right Cessation
- 2002-07-05 WO PCT/IB2002/002849 patent/WO2003009081A2/en active Application Filing
- 2002-07-05 KR KR10-2004-7000738A patent/KR20040017314A/en active IP Right Grant
- 2002-07-05 EP EP02743573A patent/EP1430375B1/en not_active Expired - Lifetime
- 2002-07-05 JP JP2003514359A patent/JP4232870B2/en not_active Expired - Fee Related
- 2002-07-15 US US10/196,049 patent/US7145965B2/en not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5774388A (en) * | 1993-08-11 | 1998-06-30 | France Telecom | Device for electronically calculating a fourier transform and method of minimizing the size of internal data paths within such a device |
EP0913778A1 (en) * | 1997-10-31 | 1999-05-06 | Integrated Silicon Systems Limited | A commutator circuit |
US6279022B1 (en) * | 1998-11-13 | 2001-08-21 | Integrated Telecom Express, Inc. | System and method for detecting symbol boundary in multi-carrier transmission systems |
Non-Patent Citations (1)
Title |
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KWAI D-M ET AL: "FFT COMPUTATION WITH LINEAR PROCESSOR ARRAYS USING A DATA-DRIVEN CONTROL SCHEME" JOURNAL OF VLSI SIGNAL PROCESSING SYSTEMS FOR SIGNAL. IMAGE, AND VIDEO TECHNOLOGY, KLUWER ACADEMIC PUBLISHERS, DORDRECHT, NL, vol. 13, no. 1, 1 August 1996 (1996-08-01), pages 57-66, XP000626220 ISSN: 0922-5773 * |
Also Published As
Publication number | Publication date |
---|---|
ATE490499T1 (en) | 2010-12-15 |
JP4232870B2 (en) | 2009-03-04 |
KR20040017314A (en) | 2004-02-26 |
EP1430375B1 (en) | 2010-12-01 |
DE60238495D1 (en) | 2011-01-13 |
CN1262951C (en) | 2006-07-05 |
WO2003009081A3 (en) | 2004-04-29 |
EP1430375A2 (en) | 2004-06-23 |
JP2004536511A (en) | 2004-12-02 |
CN1531690A (en) | 2004-09-22 |
US7145965B2 (en) | 2006-12-05 |
US20030021361A1 (en) | 2003-01-30 |
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