JP2006211134A - Apparatus and method of demodulating signal, and signal demodulation program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain demodulation data of a desired phase without regulating the phase of the demodulation data after a fast Fourier transformation is performed. <P>SOLUTION: A signal demodulator which demodulates an effective symbol from an input signal string to which spacing data based on the effective symbol before each effective symbol is added includes a symbol zone detection unit which detects one effective symbol and a symbol zone including spacing data located before the one effective symbol from the input signal string, a transformation range determination part which determines the transformation range as the range on which a fast Fourier transformation should be performed, a sequence replacer which replaces the sequence of at least the partial data of the data shown by the input signal string of the transformation range, and a fast Fourier transforming part which performs the fast Fourier transformation on the data shown by the input signal string of the transformation range and outputs the demodulation data which demodulates the effective symbol. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a signal demodulation device, a signal demodulation method, and a signal demodulation program. In particular, the present invention relates to a signal demodulator that demodulates an effective symbol from an input signal sequence in which interval data based on the effective symbol is added before each effective symbol.

  Conventionally, an OFDM (Orthogonal Frequency Division Multiplex) transmission method is known as a signal transmission method in information communication such as MMAC (Multimedia Mobile Access) (see, for example, Patent Document 1).

In the OFDM transmission method, in order to avoid intersymbol interference caused by a reflected wave transmitted through a path different from the main path, which is called multipath interference, the last part of the effective symbol is used as interval data positioned before the effective symbol. It is added. In the OFDM transmission system, the effective symbol is demodulated by performing fast Fourier transform on the data indicating the received effective symbol.
JP 2003-324406 A

  In the OFDM transmission system, in order to avoid intersymbol interference due to the preceding wave, the range in which the fast Fourier transform is performed is moved before the effective symbol range, and the predetermined position in the effective symbol is changed from the predetermined position in the interval data. The range may be up to. Since the interval data coincides with the end portion of the effective symbol, the effective symbol can be normally demodulated even when fast Fourier transform is performed on data in such a range. However, in this case, since the start position of the fast Fourier transform range does not match the start position of the effective symbol, the phase of the demodulated data is different from the original phase of the demodulated data. For this reason, in the conventional signal demodulating device, it is necessary to adjust the phase of the demodulated data after performing the fast Fourier transform, resulting in an increase in load and processing time in the demodulation processing.

  Accordingly, an object of the present invention is to provide a signal demodulation device, a signal demodulation method, and a signal demodulation program that can solve the above-described problems. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous specific examples of the present invention.

  In order to solve the above problem, in the first embodiment of the present invention, a signal demodulator that demodulates an effective symbol from an input signal sequence in which interval data based on the effective symbol is added before each effective symbol. A symbol interval detector for detecting a symbol interval including one effective symbol and interval data located before the effective symbol from the input signal sequence, and fast Fourier transform should be performed among the symbol intervals. The conversion range determining unit that determines the conversion range that is the range, the order changing unit that changes the order of at least some of the data indicated by the input signal sequence of the conversion range, and the order of at least some of the data are changed. In addition, high-speed Fourier transform is performed on the data indicated by the input signal sequence within the conversion range, and demodulated data obtained by demodulating effective symbols is output. And a Rie conversion unit.

  The conversion range determination unit may determine the conversion range by setting the start position of the conversion range to a predetermined position in the interval data and making the size of the conversion range substantially the same as the size of the effective symbol. The reordering unit moves the data from the start position of the conversion range to the end position of the interval data from the data indicated by the input signal string of the conversion range after the data from the start position of the valid symbol to the end position of the conversion range. You may let them.

  The signal demodulating apparatus further includes an input buffer for holding the data sequence of the input signal sequence in the order of input, and the order changing unit changes the read address from the address indicating the start position of the effective symbol to the address indicating the end position of the conversion range. The first reading unit that reads the data held in the input buffer and outputs the read data to the fast Fourier transform unit, and the first reading unit reads the data at the end position of the conversion range, The read address is sequentially changed from the address indicating the start position of the conversion range to the address indicating the end position of the interval data, while reading the data held in the input buffer, and outputting the read data to the fast Fourier transform unit. 2 reading units.

  The order changing unit includes a conversion range buffer that holds data indicated by the input signal sequence in the conversion range, and data from the start position of the conversion range to the end position of the interval data among the data indicated by the input signal sequence in the conversion range buffer. Of the data indicated by the first writing unit and the input signal sequence to be written, data from the beginning position of the effective symbol to the end position of the conversion range, the first writing unit in the conversion range buffer is the data at the start position of the conversion range The second writing unit to be written immediately before the writing position and the data indicated by the input signal sequence in the conversion range written by the first writing unit and the second writing unit are read from the conversion range buffer and output to the fast Fourier transform unit. And an output unit.

  The order changing unit selects one of a temporary buffer that holds data from the start position of the conversion range to the end position of the interval data, data indicated by the input signal sequence, and data held in the temporary buffer, A selection output unit that outputs to the fast Fourier transform unit, and the selection output unit selects the input signal sequence while data from the beginning position of the effective symbol to the end position of the conversion range is input as the input signal sequence. Then, after the data at the end position of the conversion range is output to the fast Fourier transform unit, the data held in the temporary buffer may be selected and output.

  The signal demodulating apparatus further includes an input buffer for holding data indicated by the input signal sequence, and the conversion range determining unit determines a plurality of different conversion ranges for the data in the same symbol section held by the input buffer. For each of the plurality of ranges, the fast Fourier transform unit demodulates the effective symbols, and among the plurality of conversion ranges, the conversion range in which the fast Fourier transform unit was able to demodulate the effective symbols is changed to other symbol intervals. The conversion range may be used.

  Further, in the second embodiment of the present invention, there is provided a signal demodulation method for demodulating an effective symbol from an input signal sequence in which interval data based on the effective symbol is added before each effective symbol. A symbol interval detection stage for detecting a symbol interval including one effective symbol and interval data positioned before the one effective symbol, and a conversion range that is a range in which fast Fourier transform is to be performed among the symbol intervals. The conversion range determination stage to be determined, the order change stage for switching the order of at least a part of the data indicated by the input signal string of the conversion range, and the input of the conversion range in which the order of at least a part of the data is changed Fast Fourier transform stage that performs fast Fourier transform on the data indicated by the signal sequence and outputs demodulated data demodulated effective symbols Provided with a door. In the conversion range determination step, the conversion range may be determined by setting the start position of the conversion range to a predetermined position in the interval data and making the size of the conversion range substantially the same as the size of the effective symbol.

  Further, in the third aspect of the present invention, signal demodulation that causes a computer to function as a signal demodulating device that demodulates an effective symbol from an input signal sequence in which interval data based on the effective symbol is added before each effective symbol. A computer program comprising: a symbol section detecting unit for detecting a symbol section including one effective symbol and interval data located before the one effective symbol from an input signal sequence; A conversion range determining unit that determines a conversion range that is a range to be converted, an order changing unit that switches the order of at least some of the data indicated by the input signal sequence of the conversion range, and at least some of the data Fast Fourier transform is performed on the data indicated by the input signal sequence in the conversion range with the order of To function as a signal demodulating apparatus and a fast Fourier transform unit to output the demodulated data obtained by demodulating the symbols. The conversion range determination unit may determine the conversion range by setting the start position of the conversion range to a predetermined position in the interval data and making the size of the conversion range substantially the same as the size of the effective symbol.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  According to the present invention, demodulated data having a desired phase can be obtained without adjusting the phase of demodulated data after performing fast Fourier transform.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 is a block diagram illustrating an example of a functional configuration of a signal demodulation device 10 according to the present embodiment. The signal demodulator 10 according to the present embodiment demodulates an effective symbol from an input signal sequence in which interval data based on the effective symbol is added before each effective symbol. Then, the signal demodulating device 10 performs demodulation by switching the order of the data indicated by the input signal sequence, thereby adjusting the demodulated data start position and the effective symbol start position without adjusting the phase of the demodulated data after demodulation. The purpose is to match.

  The signal demodulating apparatus 10 according to the present embodiment includes an input buffer 100, a symbol interval detecting unit 110, a conversion range determining unit 120, a reordering unit 130, and a fast Fourier transform unit 140. The input buffer 100 holds the data sequence of the input signal sequence in the order of input. The symbol interval detection unit 110 includes, from the input signal sequence held in the input buffer 100, a symbol including one effective symbol and interval data based on the one effective symbol, which is positioned before the one effective symbol. Detect intervals. Here, the interval data is data transmitted during a so-called guard interval, and may be substantially the same data as the end portion of the effective symbol. Then, the symbol interval detection unit 110 outputs information indicating the detected symbol interval to the conversion range determination unit 120. The transform range determination unit 120 determines a transform range that is a range in which fast Fourier transform is to be performed, among the symbol sections detected by the symbol section detection unit 110. Then, the conversion range determining unit 120 outputs information indicating the determined conversion range to the order changing unit 130.

  The order changing unit 130 reads from the input buffer 100 data indicated by the input signal string in the conversion range determined by the conversion range determination unit 120. Then, the order changing unit 130 changes the order of at least some of the read data. Then, the order changing unit 130 outputs the data whose order has been changed to the fast Fourier transform unit 140. The fast Fourier transform unit 140 performs fast Fourier transform on the data indicated by the input signal sequence in the transform range, in which the order of at least a part of the data is switched by the order switching unit 130. Then, the fast Fourier transform unit 140 outputs demodulated data obtained by demodulating effective symbols included in the input signal sequence in the section detected by the symbol section detection unit 110, obtained as a result of the fast Fourier transform.

  According to the signal demodulator 10 according to the present embodiment, fast Fourier transform can be performed by changing the order of data indicated by the input signal sequence. The phase of the demodulated data can be controlled by controlling how the data order is changed, and demodulated data having a desired phase can be output.

  FIG. 2 shows an example of processing in the order changing unit 130 according to the present embodiment. FIG. 2A shows an example of an input signal sequence held in the input buffer 100 according to the present embodiment. FIG. 2B shows an example of an input signal sequence whose order has been changed by the order changing unit 130 according to the present embodiment.

  The symbol interval detection unit 110 detects a symbol interval 200 including the effective symbol 210 and the interval data 220 positioned before the effective symbol 210 from the input signal sequence held in the input buffer 100. Then, the transform range determining unit 120 determines a transform range in which fast Fourier transform is to be performed in the input signal sequence of the symbol section 200. Specifically, the conversion range determination unit 120 sets the start position of the conversion range to a predetermined position of the interval data 220, sets the size of the conversion range to be substantially the same as the size of the effective symbol 210, and converts the conversion range 230. To decide. In addition, each of A1 to Am and B1 to Bn shown in the figure is a sample point of the fast Fourier transform in the input signal sequence in the transform range 230.

  Since the interval data 220 is substantially the same as the data at the end of the effective symbol 210, the conversion range 230 is determined as described above so that the start position of the conversion range 230 does not have to coincide with the start position of the effective symbol 210. The data substantially the same as the data included in the effective symbol 210 can be demodulated. Then, by making the start position of the conversion range 230 before the start position of the effective symbol 210, the preceding wave of the symbol section following the symbol section 200 is received superimposed on the end of the effective symbol 210. Effective symbols can be demodulated without being affected by intersymbol interference.

  Then, the order changing unit 130 converts the data from the start position A1 of the conversion range 230 to the end position Am of the interval data 220 from the data indicated by the input signal sequence of the conversion range 230 from the start position B1 of the effective symbol 210. It is moved after the data up to the end position Bn of the range 230, and the conversion source data 240 is generated. Then, the fast Fourier transform unit 140 performs fast Fourier transform on the generated conversion source data 240 to generate demodulated data.

  The interval data 220 is substantially the same as the data at the end of the effective symbol 210, and the length of the conversion range 230 is substantially the same as the length of the effective symbol 210. Therefore, by changing the order of the data as described above, The order changing unit 130 can generate the conversion source data 240 indicating a sequence substantially the same as the data sequence of the valid symbols 210. As a result, even when the leading position of the conversion range 230 is not matched with the leading position of the effective symbol 210, substantially the same conversion source data as when the leading position of the conversion range 230 is matched with the leading position of the valid symbol 210 240 can be used to demodulate the effective symbol 210.

  Note that, as the conversion range determined by the conversion range determination unit 120 is positioned earlier, the strength against intersymbol interference due to the preceding wave in the subsequent symbol section is improved, while the interval data is substantially shortened, The strength against intersymbol interference due to multipath decreases. Here, since the magnitude of the influence of the preceding wave and the multipath depends on the reception environment of the signal, the conversion range determination unit 120 does not always use a predetermined conversion range, but depends on the reception environment. It is preferable that the optimum conversion range can be detected. For example, the transform range determining unit 120 determines a plurality of different transform ranges for the data of the same symbol section held by the input buffer 100, and thereby performs a fast Fourier transform unit for each of the plurality of transform ranges. The effective range may be demodulated by 140, and the conversion range in which the fast Fourier transform unit 140 can demodulate the effective symbol among the plurality of conversion ranges may be set as the conversion range in another symbol period. Thereby, it is possible to detect the optimum conversion range and demodulate the effective symbol with high accuracy.

  FIG. 3 is a flowchart showing an example of the flow of processing in the signal demodulation method using the signal demodulator 10 according to this embodiment. First, the input buffer 100 holds the data sequence of the input signal sequence in the order of input (S1000). Subsequently, the symbol interval detection unit 110 detects a symbol interval including one effective symbol and interval data located before the one effective symbol from the input signal sequence held in the input buffer 100 ( S1010). For example, the symbol section detection unit 110 can detect the correlation between the interval data candidate having a predetermined length in the data indicated by the input signal sequence and the data following the interval data candidate, and can detect a high correlation. In this case, the interval data candidate in this case may be detected as interval data, and data having a predetermined length following the interval data may be detected as an effective symbol corresponding to the interval data.

  Subsequently, the transform range determination unit 120 determines a transform range in which fast Fourier transform is to be performed among the symbol sections detected by the symbol section detection unit 110 (S1020). Subsequently, the order changing unit 130 changes the order of at least some of the data indicated by the input signal string in the conversion range determined by the conversion range determining unit 120 (S1030). Subsequently, the fast Fourier transform unit 140 performs fast Fourier transform on the data in which the order of at least a part of the data is changed, and outputs demodulated data obtained by demodulating the effective symbols (S1040).

  FIG. 4 is a block diagram illustrating a first example of the functional configuration of the order changing unit 130 according to the present embodiment. The order changing unit 130 in this example includes a first reading unit 300 and a second reading unit 302. The first reading unit 300 reads the data held in the input buffer 100 while sequentially changing the read address from the address indicating the effective symbol start position to the address indicating the end position of the conversion range. Then, the first reading unit 300 outputs the read data to the fast Fourier transform unit 140. Further, when the first reading unit 300 reads the data at the end position of the conversion range, the first reading unit 300 notifies the second reading unit 302 to that effect. The second read unit 302 sequentially reads the read address from the address indicating the start position of the conversion range to the address indicating the end position of the interval data after the first read unit 300 reads the data at the end position of the conversion range. While changing, the data held in the input buffer 100 is read. Then, the second reading unit 302 outputs the read data to the fast Fourier transform unit 140.

  According to the signal demodulator 10 according to the present embodiment, after the first reading unit 300 reads and outputs data from the head position of the effective symbol to the end position of the conversion range, the second reading unit 302 reads the data from the head position of the conversion range. By reading and outputting data from the position to the end position of the interval data, it is possible to perform fast Fourier transform on the data in the same sequence as the data in the effective symbols. Thus, demodulated data having a desired phase can be output without adjusting the phase of the demodulated data after performing the fast Fourier transform.

  FIG. 5 is a flowchart illustrating an example of S1030 in the case where the order changing unit 130 illustrated in FIG. 4 is used. First, the first reading unit 300 reads the data held in the input buffer 100 while sequentially changing the read address from the address indicating the head position of the effective symbol to the address indicating the end of the conversion range, and reads the read data. The result is output to the fast Fourier transform unit 140 (S1100). Subsequently, when the first reading unit 300 reads and outputs the data at the end position of the conversion range, the first reading unit 300 notifies the second reading unit 302 to that effect (S1110). Subsequently, the second read unit 302 reads and reads the data held in the input buffer 100 while sequentially changing the read address from the address indicating the start position of the conversion range to the address indicating the end position of the interval data. The obtained data is output to the fast Fourier transform unit 140 (S1120).

  FIG. 6 is a block diagram illustrating a second example of the functional configuration of the order changing unit 130 according to the present embodiment. The order changing unit 130 in this example includes a first writing unit 320, a second writing unit 322, a conversion range buffer 324, and an output unit 326. The first writing unit 320 writes the data from the start position of the conversion range to the end position of the interval data in the conversion range buffer 324 among the data indicated by the input signal sequence held in the input buffer 100. The second writing unit 322 uses the first writing unit in the conversion range buffer 324 to transfer the data from the start position of the effective symbol to the end position of the conversion range among the data indicated by the input signal sequence held in the input buffer. 320 writes the data at the beginning of the conversion range immediately before the written position. For example, when the first writing unit 320 writes data at the start position of the conversion range to a predetermined address in the conversion range buffer 324, the second writing unit 322 extends from the start position of the effective symbol to the end position of the conversion range. This data may be written immediately before the position indicated by the address.

  The conversion range buffer 324 holds data indicated by the input signal string in the conversion range among the data held by the input buffer 100. The output unit 326 reads from the conversion range buffer 324 the data indicated by the conversion range input signal sequence written by the first writing unit 320 and the second writing unit 322 and outputs the data to the fast Fourier transform unit 140.

  According to the signal demodulating device 10 according to the present embodiment, the data held in the input buffer 100 is written in the conversion range buffer 324 in substantially the same arrangement as the data in the effective symbols, and is output to the fast Fourier transform unit 140. be able to. Thus, demodulated data having a desired phase can be output without adjusting the phase of the demodulated data after performing the fast Fourier transform.

  FIG. 7 is a flowchart illustrating an example of S1030 when the order changing unit 130 illustrated in FIG. 6 is used. First, the first writing unit 320 writes the data from the start position of the conversion range to the end position of the interval data among the data indicated by the input signal sequence held in the input buffer 100 in the conversion range buffer 324 ( S1200). Subsequently, the second writing unit 322 converts the data from the start position of the effective symbol to the start position of the conversion range, among the data indicated by the input signal sequence held in the input buffer, by the first writing unit 320. The data at the head position of the range is written immediately before the written position (S1210). Subsequently, the output unit 326 reads from the conversion range buffer 324 the data indicated by the conversion range input signal sequence written by the first writing unit 320 and the second writing unit 322, and outputs the data to the fast Fourier transform unit 140. (S1220).

  FIG. 8 is a block diagram illustrating a third example of the functional configuration of the order changing unit 130 according to the present embodiment. The order changing unit 130 in this example includes an input unit 340, a temporary buffer 342, and a selection output unit 344. The input unit 340 inputs data indicated by the input signal sequence in the conversion range determined by the conversion range determination unit 120 among the data held in the input buffer 100 in the order of the input signal sequence. Then, the input unit 340 outputs the input data to the temporary buffer 342 and the selection output unit 344. The temporary buffer 342 holds data from the input position 340 from the start position of the conversion range to the end position of the interval data.

  The selection output unit 344 selects either the data indicated by the input signal sequence received from the input unit 340 or the data held in the temporary buffer. Then, the selection output unit 344 outputs the selected data to the fast Fourier transform unit 140. Specifically, the selection output unit 344 selects and outputs an input signal sequence while data from the start position of the effective symbol to the end position of the conversion range is input from the input unit 340 as an input signal sequence. To do. The selection output unit 344 outputs the data at the end position of the conversion range to the fast Fourier transform unit 140, and then selects and outputs the data held in the temporary buffer.

  According to the signal demodulating device 10 according to the present embodiment, the data of the portion included in the interval data among the data indicated by the input signal sequence in the conversion range is held in the temporary buffer 342, and the data of the portion included in the effective symbol is stored. Can be output to the fast Fourier transform unit 140 after being output to the fast Fourier transform unit 140. As a result, data in the same sequence as the data in the effective symbol can be output to the fast Fourier transform unit 140, so that after performing the fast Fourier transform, a desired phase can be obtained without adjusting the phase of the demodulated data. Demodulated data can be output.

  FIG. 9 is a flowchart illustrating an example of S1030 in the case where the order changing unit 130 illustrated in FIG. 8 is used. First, the input unit 340 starts to input data indicated by the input signal string in the conversion range determined by the conversion range determination unit 120 among the data held in the input buffer 100 (S1300). Subsequently, the order changing unit 130 determines whether or not data from the start position of the effective symbol to the end position of the conversion range is input (S1310). If it is determined that data from the start position of the conversion range to the end position of the interval data is input (S1310: No), the temporary buffer 342 stores and holds the input data (S1320). . Then, the order changing unit 130 returns the process to S1310, and again determines the input data.

  On the other hand, when it is determined that data from the beginning position of the effective symbol to the end position of the conversion range is input (S1310: Yes), the selection output unit 344 selects the input data and performs fast Fourier transform. The data is output to the unit 140 (S1330). Subsequently, the order changing unit 130 determines whether or not the data at the end position of the conversion range is output to the fast Fourier transform unit 140 (S1340). If it is determined that the data at the end position of the conversion range is not output (S1340: No), the order changing unit 130 returns the process to S1310, and again determines the input data. On the other hand, when it is determined that the data at the end position of the conversion range has been output (S1340: Yes), the selection output unit 344 holds the temporary buffer 342 from the start position of the conversion range to the end position of the interval data. Are selected and output to the fast Fourier transform unit 140 (S1350).

  FIG. 10 is a block diagram illustrating an example of a hardware configuration of a computer 1500 according to the present embodiment. A computer 1500 according to an embodiment of the present invention is connected to a host peripheral having a CPU 1505, a RAM 1520, a graphic controller 1575, and a display device 1580 connected to each other by a host controller 1582, and to the host controller 1582 by an input / output controller 1584. An input / output unit having a communication interface 1530, a hard disk drive 1540, and a CD-ROM drive 1560, and a legacy input / output unit having a ROM 1510, a flexible disk drive 1550, and an input / output chip 1570 connected to the input / output controller 1584. Prepare.

  The host controller 1582 connects the RAM 1520 to the CPU 1505 and the graphic controller 1575 that access the RAM 1520 at a high transfer rate. The CPU 1505 operates based on programs stored in the ROM 1510 and the RAM 1520 and controls each unit. The graphic controller 1575 acquires image data generated by the CPU 1505 or the like on a frame buffer provided in the RAM 1520 and displays the image data on the display device 1580. Alternatively, the graphic controller 1575 may include a frame buffer that stores image data generated by the CPU 1505 or the like.

  The input / output controller 1584 connects the host controller 1582 to the communication interface 1530, the hard disk drive 1540, and the CD-ROM drive 1560, which are relatively high-speed input / output devices. The communication interface 1530 communicates with other devices via a network. The hard disk drive 1540 stores programs and data used by the CPU 1505 in the computer 1500. The CD-ROM drive 1560 reads a program or data from the CD-ROM 1595 and provides it to the hard disk drive 1540 via the RAM 1520.

  The input / output controller 1584 is connected to the ROM 1510, the flexible disk drive 1550, and the relatively low-speed input / output device of the input / output chip 1570. The ROM 1510 stores a boot program executed when the computer 1500 is started up, a program depending on the hardware of the computer 1500, and the like. The flexible disk drive 1550 reads a program or data from the flexible disk 1590 and provides it to the hard disk drive 1540 via the RAM 1520. The input / output chip 1570 connects various input / output devices via the flexible disk drive 1550 and, for example, a parallel port, a serial port, a keyboard port, a mouse port, and the like.

  The signal demodulation program provided to the hard disk drive 1540 via the RAM 1520 is stored in a recording medium such as the flexible disk 1590, the CD-ROM 1595, or an IC card and provided by the user. The signal demodulation program is read from the recording medium, installed in the hard disk drive 1540 in the computer 1500 via the RAM 1520, and executed by the CPU 1505. A signal demodulation program installed and executed in the computer 1500 works on the CPU 1505 or the like to cause the computer 1500 to function as the signal demodulation device described with reference to FIGS.

  The program shown above may be stored in an external storage medium. As the storage medium, in addition to the flexible disk 1590 and the CD-ROM 1595, an optical recording medium such as a DVD or PD, a magneto-optical recording medium such as an MD, a tape medium, a semiconductor memory such as an IC card, or the like can be used. Further, a storage device such as a hard disk or a RAM provided in a server system connected to a dedicated communication network or the Internet may be used as a recording medium, and the program may be provided to the computer 1500 via the network.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

It is a block diagram which shows an example of a function structure of the signal demodulation apparatus 10 which concerns on embodiment of this invention. It is a figure which shows an example of the process in the order change part 130 which concerns on embodiment of this invention. It is a flowchart which shows an example of the flow of a process in the signal demodulation method using the signal demodulation apparatus 10 which concerns on embodiment of this invention. It is a block diagram which shows the 1st example in the function structure of the order change part 130 which concerns on embodiment of this invention. 5 is a flowchart illustrating an example of S1030 in the case where the order changing unit 130 illustrated in FIG. 4 is used. It is a block diagram which shows the 2nd example in the function structure of the order change part 130 which concerns on embodiment of this invention. 7 is a flowchart illustrating an example of S1030 in the case where the order changing unit 130 illustrated in FIG. 6 is used. It is a block diagram which shows the 3rd example in the function structure of the order change part 130 which concerns on embodiment of this invention. It is a flowchart which shows an example of S1030 in the case of using the order change part 130 shown in FIG. It is a block diagram which shows an example of the hardware constitutions of the computer 1500 concerning embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Signal demodulation apparatus 100 Input buffer 110 Symbol area detection part 120 Conversion range determination part 130 Order change part 140 Fast Fourier transform part 200 Symbol area 210 Effective symbol 220 Spacing data 300 1st reading part 302 2nd reading part 320 1st writing part 322 Second writing unit 324 Conversion range buffer 326 Output unit 340 Input unit 342 Temporary buffer 344 Selection output unit

Claims (11)

A signal demodulator that demodulates the effective symbol from an input signal sequence to which interval data based on the effective symbol is added before each effective symbol,
A symbol interval detector for detecting a symbol interval including one effective symbol and the interval data located before the one effective symbol from the input signal sequence;
Among the symbol sections, a transform range determining unit that determines a transform range that is a range in which fast Fourier transform is to be performed;
An order changing unit for changing the order of at least some of the data indicated by the input signal sequence in the conversion range;
A fast Fourier transform unit that performs fast Fourier transform on the data indicated by the input signal sequence in the transform range in which the order of the at least a part of the data is switched, and outputs demodulated data obtained by demodulating the effective symbols; A signal demodulator comprising:   The conversion range determination unit determines the conversion range by setting the start position of the conversion range to a predetermined position in the interval data and making the size of the conversion range substantially the same as the size of the effective symbol. Item 2. The signal demodulator according to Item 1.   The order changing unit is configured to convert data from the start position of the conversion range to the end position of the interval data from the data indicated by the input signal sequence of the conversion range, from the start position of the effective symbol to the end of the conversion range. The signal demodulator according to claim 2, wherein the signal demodulator is moved after the data up to the position. An input buffer for holding the data sequence of the input signal sequence in the order of input;
The order changing unit
The data held in the input buffer is read while sequentially changing the read address from the address indicating the start position of the effective symbol to the address indicating the end position of the conversion range, and the read data is converted to the fast Fourier transform unit. A first readout unit for outputting to
After the first reading unit reads the data at the end position of the conversion range, the read address is sequentially changed from the address indicating the start position of the conversion range to the address indicating the end position of the interval data, The signal demodulator according to claim 3, further comprising: a second reading unit that reads data held in the input buffer and outputs the read data to the fast Fourier transform unit. The order changing unit
A conversion range buffer for holding data indicated by the input signal sequence of the conversion range;
A first writing unit that writes data from the start position of the conversion range to the end position of the interval data among the data indicated by the input signal sequence in the conversion range buffer;
Of the data indicated by the input signal string, the data from the start position of the effective symbol to the end position of the conversion range is written, and the first writing unit in the conversion range buffer writes the data at the start position of the conversion range. A second writing unit for writing immediately before the position,
An output unit that reads out data indicated by the input signal sequence in the conversion range written by the first writing unit and the second writing unit from the conversion range buffer and outputs the data to the fast Fourier transform unit. The signal demodulator according to claim 1. The order changing unit
A temporary buffer that holds data from the start position of the conversion range to the end position of the interval data;
A selection output unit that selects any one of the data indicated by the input signal sequence and the data held in the temporary buffer and outputs the selected data to the fast Fourier transform unit;
The selection output unit selects and outputs the input signal sequence while data from the start position of the effective symbol to the end position of the conversion range is input as the input signal sequence, and outputs the end of the conversion range. The signal demodulator according to claim 3, wherein after the position data is output to the fast Fourier transform unit, the data held in the temporary buffer is selected and output. An input buffer for holding data indicated by the input signal sequence;
The transform range determining unit determines the plurality of different transform ranges from each other for the data of the same symbol section held by the input buffer, and thereby the fast Fourier transform unit for each of the plurality of ranges. The modulation range in which the effective symbol is demodulated and the fast Fourier transform unit can demodulate the effective symbol among the plurality of conversion ranges is set as the conversion range in the other symbol period. Signal demodulator. A signal demodulation method for demodulating the effective symbol from an input signal sequence to which interval data based on the effective symbol is added before each effective symbol,
A symbol interval detection step of detecting a symbol interval including one effective symbol and the interval data located before the one effective symbol from the input signal sequence;
A transform range determining step for determining a transform range that is a range in which fast Fourier transform is to be performed among the symbol sections;
Of the data indicated by the input signal sequence in the conversion range, an order changing step for changing the order of at least some of the data;
A fast Fourier transform stage for performing fast Fourier transform on the data indicated by the input signal sequence in the transform range, in which the order of the at least part of the data is switched, and outputting demodulated data obtained by demodulating the effective symbols; A signal demodulation method comprising:   The conversion range determining step determines the conversion range by setting the start position of the conversion range to a predetermined position in the interval data and making the size of the conversion range substantially the same as the size of the effective symbol. Item 9. The signal demodulation method according to Item 8. A signal demodulation program that causes a computer to function as a signal demodulator that demodulates the effective symbol from an input signal sequence to which interval data based on the effective symbol is added before each effective symbol,
The computer,
A symbol interval detector for detecting a symbol interval including one effective symbol and the interval data located before the one effective symbol from the input signal sequence;
Among the symbol sections, a transform range determining unit that determines a transform range that is a range in which fast Fourier transform is to be performed;
An order changing unit for changing the order of at least some of the data indicated by the input signal sequence in the conversion range;
A fast Fourier transform unit that performs fast Fourier transform on the data indicated by the input signal sequence in the transform range in which the order of the at least a part of the data is switched, and outputs demodulated data obtained by demodulating the effective symbols; A signal demodulation program that functions as a signal demodulator.   The conversion range determination unit determines the conversion range by setting the start position of the conversion range to a predetermined position in the interval data and making the size of the conversion range substantially the same as the size of the effective symbol. Item 11. A signal demodulation program according to Item 10.

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