JP2012109951A - Interference wave extractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interference wave extractor capable of precisely extracting interference wave signals by removing a desired wave from a broadcast wave mixed with the desired wave and the interference wave.SOLUTION: A desired wave extraction part 10 inputs received signals mixed with desired waves and interference waves, and extracts the signals of the desired waves from the received signals utilizing the fact that the reception level of the desired waves is higher than that of the interference waves. A transmission channel characteristics calculation part 11 calculates a transmission channel characteristics using the received signals and preset signals. A transmission channel characteristics addition part 12 inputs desired wave signals from a desired wave extraction part 10, inputs transmission channel characteristics from the transmission channel characteristics calculation part 11, adds a transmission channel characteristics to the signals of the desired waves, and generates desired wave replica signals. A delay unit 13 delays reception signals for the amount of processing time of the transmission channel characteristics calculation part 11 and the transmission channel characteristic addition part 12. A desired wave cancellation part 14 subtracts desired wave replica signals from the reception signals delayed, and extracts the interference wave signals.

Description

  The present invention relates to a technique for extracting an interference wave from a broadcast wave receiving interference of another broadcast wave without stopping the broadcast wave of a desired wave.

  The transmission system of terrestrial digital broadcasting is defined in the standard of ARIB STD-B31 (Non-Patent Document 1), and terrestrial digital broadcasting services according to this transmission system are provided. However, in providing a terrestrial digital broadcast service, a broadcast wave transmitted from a terrestrial digital broadcast relay station may interfere with a desired wave.

  Specifically, digital broadcast receivers that receive terrestrial digital broadcast waves transmitted from relay stations of digital terrestrial broadcast media (NHK General / Sendai, NHK Education / Sendai, Sendai Broadcasting, etc.) In some cases, the terrestrial digital broadcast wave transmitted from a relay station in another area may be affected by interference. In order to solve this interference problem, the broadcaster who is the user conducts a detailed reception investigation and identifies the interference station that is transmitting the interference wave.

  However, even if a normal digital broadcast receiving apparatus or a digital broadcast receiving apparatus having a network ID estimation function is used, the interference station cannot be specified. This is because the reception level of the interference wave is usually lower than the reception level of the desired wave. Under such circumstances, the normal digital broadcast reception device or the digital broadcast reception device having the network ID estimation function is This is because a desired wave having a high reception level is demodulated.

  Therefore, in order to conduct a survey to identify interference stations, broadcasters temporarily set a broadcast suspension time zone in the late-night time zone, and in the short time zone of several hours, terrestrial digital broadcasting that is a desired wave Stop the transmitting device of the transmitting station (parent station) that is transmitting the wave. That is, the broadcaster identifies the interference station by stopping the desired wave and investigating the interference wave in the absence of the desired wave.

  In this case, even in an environment where the desired wave and the interference wave are mixed, if the signal of the desired wave is removed from the received signal and only the signal of the interference wave can be extracted with high accuracy, the broadcaster can extract it. The interference station can be identified by investigating the interference wave. That is, the broadcaster can investigate the interference wave and identify the interference station in any time zone without stopping the transmission device of the transmission station.

  Therefore, in order to identify an interference station, an apparatus that removes a desired signal from a received signal and extracts only an interference signal with high accuracy has been desired. However, conventionally, there is known an apparatus that extracts a signal of a desired wave with high accuracy by removing the signal of the interference wave from the received signal in an environment where the desired wave and the interference wave are mixed (for example, patents). No reference has been made to a device for removing a desired signal from a received signal.

JP 2000-175079 A

ARIB STD-B31, "Transmission method for digital terrestrial television broadcasting"

  As described above, in order to identify an interference station in any time zone without stopping the transmission apparatus of the transmission station, the signal of the desired wave is removed from the received signal, and only the signal of the interference wave is extracted with high accuracy. An apparatus is desired. Here, since a device that removes a signal of an interference wave from a received signal and extracts only a signal of a desired wave is known as in the device of Patent Document 1, a desired signal removal technique can be used to obtain a desired signal. It is assumed that the apparatus is configured.

  For example, as a conventional signal removal technique, there is a technique in which an antenna array is formed by two reception antennas, a null of the reception antenna directivity is formed in the direction of the incoming wave to be removed, and the signal power of the radio wave to be removed is suppressed. However, the arrival direction of the interference wave is not constant in the first place, and the identity is often unknown, and it is difficult to easily set the main directivity direction of the receiving antenna. Therefore, this method cannot be said to be effective for extracting only the signal of the interference wave from the received signal with high accuracy.

  It is also conceivable to use an interference cancellation technique that applies adaptive array technology using two or more array antennas. However, with this technique, the signal that is subject to interference cancellation is an interference wave having a reception level lower than that of the desired wave, and the interference wave is removed. In other words, this method is intended to remove a desired wave having a higher reception level than the interference wave (the desired device removes the desired wave having a higher reception level than the interference wave and extracts only the interference wave). Not applicable to. Therefore, this method cannot be used to extract only the interference wave signal from the received signal with high accuracy.

  Therefore, the present invention has been made to solve such a problem, and its purpose is to remove a signal of a desired wave from a broadcast wave in which a desired wave and an interference wave are mixed, and to accurately convert the signal of the interference wave. An object of the present invention is to provide an interference wave extraction device that can be extracted.

  In order to solve the above-mentioned problem, the invention of claim 1 is an interference wave extraction device that receives a broadcast wave in which a desired wave and an interference wave are mixed and extracts the interference wave from the broadcast wave, the received broadcast A desired wave extraction unit for equalizing a wave signal and extracting the desired wave signal having a reception level higher than the signal of the interference wave from the equalized broadcast wave signal; and included in the received broadcast wave A transmission line characteristic calculation unit that calculates transmission line characteristics using a reference signal that is set in advance and a preset reference signal, and a signal of the desired wave extracted by the desired wave extraction unit by the transmission line characteristic calculation unit A transmission path characteristic adding unit that adds the calculated transmission path characteristics and generates a desired wave replica signal, and subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the received broadcast wave signal. , Output the signal of the interference wave And the desired wave cancellation unit that, characterized in that it was equipped with.

  Further, the invention according to claim 2 is the interference wave extraction device according to claim 1, wherein the desired wave extraction unit extracts an A layer signal from an OFDM signal of the received broadcast wave by a BPF, and extracts the A layer signal. Demodulating, performing FFT on the demodulated A layer signal, performing equalization, extracting the A layer signal of the desired wave by symbol hard decision, IFFT outputting the A layer signal of the desired wave, A transmission path characteristic calculation unit that extracts an SP signal from the A layer signal FFTed by the desired wave extraction unit, calculates the transmission path characteristic by dividing the extracted SP signal by a preset SP signal, A transmission line characteristic adding unit generates a filter coefficient by performing an IFFT on the transmission line characteristic calculated by the transmission line characteristic calculating unit, and using the filter coefficient by an FIR filter, by the desired wave extracting unit. The desired wave replica signal is generated from the inputted A layer signal of the desired wave, and the desired wave canceling unit generates the desired signal generated by the transmission path characteristic adding unit from the A layer signal demodulated by the desired wave extracting unit. It is characterized by subtracting the wave replica signal to obtain an A layer signal of the interference wave, and modulating the A layer signal of the interference wave.

  Further, the invention of claim 3 is the interference wave extraction device according to claim 1, wherein the desired wave extraction unit demodulates the OFDM signal of the received broadcast wave, performs FFT on the demodulated signal, etc. The desired layer A signal is extracted by symbol hard decision, the desired layer A layer signal is output by IFFT, and the transmission line characteristic calculation unit is FFTed by the desired wave extraction unit. An SP signal is extracted from the received signal, and the extracted SP signal is divided by a preset SP signal to calculate a transmission line characteristic. The transmission line characteristic addition unit is calculated by the transmission line characteristic calculation unit. IFFT of the transmission line characteristics is generated to generate a filter coefficient, and a desired wave replica signal is generated from the A layer signal of the desired wave output by the desired wave extraction unit using the filter coefficient by an FIR filter, The desired wave canceling unit subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the signal demodulated by the desired wave extracting unit to obtain an interference wave signal, and modulates the interference wave signal It is characterized by.

  According to a fourth aspect of the present invention, in the interference wave extracting apparatus according to the second or third aspect, the desired wave extracting unit adds an SP signal to the A layer signal of the desired wave extracted by the symbol hard decision, It is characterized by being output after IFFT.

  The invention according to claim 5 is the interference wave extraction device according to claim 2, wherein the desired wave extraction unit uses a BPF that performs analog filter processing to obtain a first A layer signal from the received OFDM signal of the broadcast wave. The first A layer signal is demodulated, the second A layer signal is extracted from the demodulated first A layer signal by the BPF that performs digital filter processing, and the second A layer signal is FFTed Then, equalization processing is performed, the A layer signal of the desired wave is extracted by symbol hard decision, an SP signal is added to the A layer signal of the desired wave, IFFT is output, and the desired wave canceling unit is The desired layer replica signal generated by the transmission path characteristic adding unit is subtracted from the second layer A signal extracted by the desired wave extracting unit to obtain an A layer signal of the interference wave, and the A signal of the interference wave is obtained. Modulating layer signal, characterized in that.

  Further, the invention of claim 6 is the interference wave extraction device according to claim 3, wherein the desired wave extraction unit uses a BPF that performs analog filter processing to receive the first signal of the entire band from the OFDM signal of the received broadcast wave. After extracting the signal, demodulating the first signal, extracting the second signal of the entire band from the demodulated first signal by the BPF that performs digital filter processing, performing the FFT on the second signal, and then equalizing Processing, extracting the A layer signal of the desired wave by symbol hard decision, adding an SP signal to the A layer signal of the desired wave, outputting by IFFT, and the desired wave canceling unit extracting the desired wave Subtracting the desired wave replica signal generated by the transmission path characteristic adding unit from the second signal extracted by the unit to obtain an interference signal, and modulating the interference signal. That.

  The invention according to claim 7 is the interference wave extraction apparatus according to claim 5 or 6, and is further demodulated by the desired wave extraction unit, according to the first A-layer signal of claim 5 or the sixth aspect of claim 6. 7. The first A-layer signal according to claim 5 or the sixth signal according to claim 6, further comprising: a synchronous reproduction unit that performs frequency synchronous reproduction processing on a signal of 1 to obtain a frequency offset, wherein the desired wave extraction unit demodulates the signal. The frequency offset obtained by the synchronous reproduction unit is removed from the frequency of one signal, and the BPF digital filter processing is performed on the signal from which the frequency offset has been removed.

  The invention according to claim 8 is the interference wave extraction device according to claim 2, wherein a frequency synchronization reproduction process is further performed on the A layer signal demodulated by the desired wave extraction unit to obtain a frequency offset. A desired signal extraction unit that extracts a first A layer signal from the received broadcast wave OFDM signal by a BPF that performs analog filter processing, demodulates the first A layer signal, A frequency offset obtained by the synchronous reproduction unit is removed from the demodulated first A layer signal frequency, and the second A layer is removed from the first A layer signal from which the frequency offset is removed by a BPF that performs digital filter processing. After extracting the signal and performing FFT on the second A layer signal, equalization processing is performed to separate the AC and TMCC signals from the data signal. Frequency deinterleaving, time deinterleaving, demapping, bit deinterleaving, depuncture, and inner code decoding, and inner code decoding, puncture, bit interleaving, mapping, Performs time interleaving and frequency interleaving processing, obtains transmission symbols by hard symbol decision for the AC and TMCC signals, performs remodulation, and performs data modulation and remodulation on the frequency interleaving processing. The AC and TMCC signals and the predetermined SP and CP signals are combined to generate the desired layer A layer signal, and the desired layer A layer signal is output by IFFT. From the second A layer signal extracted by the desired wave extraction unit, the transmission path Subtracting the desired wave replica signal generated by sexual adding unit obtains the A-layer signal interference wave, modulates the A-layer signal of the interference wave, and wherein the.

  The invention according to claim 9 is the interference wave extraction device according to claim 3, wherein the signal demodulated by the desired wave extraction unit is further subjected to synchronous reproduction processing to obtain a frequency offset. The desired wave extraction unit extracts a first signal of the entire band from the OFDM signal of the received broadcast wave by the BPF that performs analog filter processing, demodulates the first signal, and demodulates the first signal The frequency offset obtained by the synchronous reproduction unit is removed from the frequency of the first signal, and the second signal of the entire band is extracted from the first signal from which the frequency offset is removed by the BPF that performs digital filter processing, 2 is subjected to equalization, and AC and TMCC signals are separated from the A-layer data signal. -Leave, time deinterleave, demapping, bit deinterleave, depuncture and inner code decoding are performed, and the inner code decoded signal is subjected to inner code encoding, puncture, bit interleaving, mapping, time interleaving and frequency. Interleave processing is performed, a transmission symbol is obtained by symbol hard decision for the AC and TMCC signals, remodulation is performed, and the data signal is subjected to the frequency interleaving processing, and the remodulated AC and TMCC is performed. A desired signal A layer signal is generated by combining a signal and predetermined SP and CP signals, the desired signal A layer signal is output by IFFT, and the desired wave canceling unit is connected to the desired wave extracting unit Generated from the second signal extracted by the transmission line characteristic adding unit. Obtains a signal interference wave by subtracting a desired wave replica signal, modulates the signal of the interference wave, and wherein the.

  The invention according to claim 10 is the interference wave extraction device according to claim 2, further performing a frequency synchronous reproduction process on the A layer signal demodulated by the desired wave extraction unit to obtain a frequency offset. A desired signal extraction unit that extracts a first A layer signal from the received broadcast wave OFDM signal by a BPF that performs analog filter processing, demodulates the first A layer signal, A frequency offset obtained by the synchronous reproduction unit is removed from the demodulated first A layer signal frequency, and the second A layer is removed from the first A layer signal from which the frequency offset is removed by a BPF that performs digital filter processing. After extracting the signal and performing FFT on the second A layer signal, equalization processing is performed to separate the AC and TMCC signals from the data signal. On the other hand, frequency deinterleaving, time deinterleaving, demapping, bit deinterleaving, depuncture, and inner code decoding are performed, and byte deinterleaving, energy despreading, outer code decoding, outer code decoding are performed on the inner code decoded signal. Code encoding, energy spreading, and byte interleaving are performed, and inner code encoding, puncture, bit interleaving, mapping, time interleaving, and frequency interleaving are performed on the byte interleaved signal. A transmission symbol is obtained from the signal by symbol hard decision, remodulation is performed, and the frequency interleaved data signal, the remodulated AC and TMCC signals, and predetermined SP and CP signals are combined. And said hope A layer signal of the desired wave is generated and IFFT is output to output the desired signal, and the desired wave canceling unit generates the transmission path from the second A layer signal extracted by the desired wave extracting unit. The desired wave replica signal generated by the characteristic adding unit is subtracted to obtain an A layer signal of an interference wave, and the A layer signal of the interference wave is modulated.

  The invention according to claim 11 is the interfering wave extracting device according to claim 3, wherein the signal demodulated by the desired wave extracting unit is further subjected to synchronous reproduction processing to obtain a frequency offset. The desired wave extraction unit extracts a first signal of the entire band from the OFDM signal of the received broadcast wave by the BPF that performs analog filter processing, demodulates the first signal, and demodulates the first signal The frequency offset obtained by the synchronous reproduction unit is removed from the frequency of the first signal, and the second signal of the entire band is extracted from the first signal from which the frequency offset is removed by the BPF that performs digital filter processing, 2 is subjected to equalization processing, and AC and TMCC signals are separated from the A-layer data signal. Performs each processing of tarleaving, time deinterleaving, demapping, bit deinterleaving, depuncture and inner code decoding, and for the inner code decoded signal, byte deinterleaving, energy despreading, outer code decoding, outer code coding, Each process of energy spreading and byte interleaving is performed, inner code coding, puncture, bit interleaving, mapping, time interleaving and frequency interleaving are performed on the byte interleaved signal, and the AC and TMCC signals are processed. A transmission symbol is obtained by symbol hard decision, re-modulated, the data signal subjected to the frequency interleaving process, the AC and TMCC signal subjected to the re-modulation, and a predetermined SP and CP signal are synthesized and the desired signal is obtained. Generate wave A layer signal The desired wave A layer signal is output by IFFT, and the desired wave canceling unit generates the desired signal generated by the transmission path characteristic adding unit from the second signal extracted by the desired wave extracting unit. The interference wave signal is obtained by subtracting the wave replica signal, and the interference wave signal is modulated.

  Furthermore, the invention of claim 12 resides in an interference wave extraction program for causing a computer to function as the interference wave extraction device.

  As described above, according to the present invention, it is possible to remove a signal of a desired wave from a broadcast wave in which a desired wave and an interference wave are mixed, and to extract the signal of the interference wave with high accuracy. Therefore, it is possible to extract the interference wave without stopping the transmitter of the transmitting station and stop the desired wave, and it is possible to investigate the extracted interference wave, thereby reducing the work load of the broadcaster It becomes.

It is a block diagram which shows schematic structure of the interference wave extraction apparatus by embodiment of this invention. It is a block diagram which shows the structure of the 1st (Example 1) interference wave extraction apparatus by embodiment of this invention. It is a block diagram which shows the structure of the 2nd (Example 2) interference wave extraction apparatus by embodiment of this invention. It is a block diagram which shows the structure of the 3rd (Example 3) interference wave extraction apparatus by embodiment of this invention. It is a block diagram which shows the structure of the 4th (Example 4) interference wave extraction apparatus by embodiment of this invention. It is a block diagram which shows the structure of an AFC part. It is a figure which shows the characteristic of the symbol error rate with respect to reception CN ratio in case a frequency offset exists. It is a figure which shows the symbol error rate with respect to the normalized frequency offset. It is a block diagram which shows the structure of the 5th (Example 5) interference wave extraction apparatus by embodiment of this invention. It is a block diagram which shows the structure of the 6th (Example 6) interference wave extraction device by embodiment of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the following description, terrestrial digital broadcast waves by ISDB (Integrated Services Digital Broadcasting) are targeted, and parameters necessary for processing of each component are defined in ARIB STD-B31 of Non-Patent Document 1. It shall conform to

  First, an outline of an interference wave extraction device according to an embodiment of the present invention will be described. FIG. 1 is a block diagram showing a schematic configuration of an interference wave extraction device 1. The interference wave extraction device 1 includes a desired wave extraction unit 10, a transmission path characteristic calculation unit 11, a transmission path characteristic addition unit 12, a delay unit 13, and a desired wave cancellation unit 14.

  The interference wave extraction device 1 receives a signal in which a desired wave (parent station wave) from a transmitting station (parent station) and an interference wave from the interference station are mixed, and extracts the desired wave signal from the received signal and receives the desired signal. A wave replica signal is generated, and the desired wave signal is canceled by subtracting the desired wave replica signal from the received signal, and an interference signal is extracted.

  The desired wave extraction unit 10 receives a received signal in which a desired wave and an interference wave are mixed, equalizes the received signal so that the transmission path distortion of the desired wave signal included in the received signal is eliminated, Utilizing the fact that the reception level is higher than the reception level of the interference wave, only the desired wave signal is extracted from the equalized reception signal, and the extracted desired wave signal is output to the transmission path characteristic adding unit 12.

  The transmission path characteristic calculation unit 11 receives a reception signal in which a desired wave and an interference wave are mixed, receives the reception signal and a preset reference signal (a signal whose modulation content is known at the time of transmission, and a pilot signal (SP signal ) Is also used to calculate the transmission line characteristic, and the obtained transmission line characteristic is output to the transmission line characteristic addition unit 12.

  The transmission path characteristic adding unit 12 receives the desired wave signal from the desired wave extracting section 10, receives the transmission path characteristic from the transmission path characteristic calculating section 11, adds the transmission path characteristic to the desired wave signal, and generates the desired wave replica signal. And the desired wave replica signal is output to the desired wave canceling unit 14. Here, the desired wave replica signal is a signal of only the desired wave component included in the received signal in which the desired wave and the interference wave received by the interference wave extracting apparatus 1 are mixed.

  The delay unit 13 receives a reception signal in which a desired wave and an interference wave are mixed, and the desired wave replica signal is received by the desired wave extraction unit 10, the transmission path characteristic calculation unit 11, and the transmission path characteristic addition unit 12. A delay corresponding to the generated processing time is added, and the delayed received signal is output to the desired wave cancel unit 14. Thereby, in the desired wave cancellation part 14, the timing which subtracts a desired wave replica signal from the received signal in which the desired wave and the interference wave were mixed can be matched.

  The desired wave canceling unit 14 receives the desired wave replica signal from the transmission path characteristic adding unit 12, receives the delayed received signal from the delay unit 13, subtracts the desired wave replica signal from the received signal, Output a signal. Thereby, only the desired wave signal is removed from the reception signal in which the desired wave and the interference wave are mixed, and the interference wave signal is extracted.

  Hereinafter, devices embodying the interference wave extraction device 1 of FIG. 1 are shown in Examples 1 to 6, and each of Examples 1 to 6 will be described in detail.

  First, the interference wave extraction apparatus according to the first embodiment will be described. FIG. 2 is a block diagram illustrating a configuration of the interference wave extraction apparatus according to the first embodiment. The interference wave extracting device 1-1 includes a BPF (Band Pass Filter) 21, an A / D converter 22, a quadrature demodulator (QDEM) 23, a synchronous reproducing unit 24, a window processing unit 25, A delay unit 26, an FFT (Fast Fourier Transform) unit 27, an SP signal (scattered pilot) extraction unit 28, a transmission path characteristic calculation unit 29, an equalization unit 30, a filter coefficient generation unit 31, Symbol determination unit 32, remodulation unit 33, IFFT (Inverse Fast Fourier Transform) unit 34, GI (Guard Interval) adding unit 35, FIR (Finite Imp) An ulse response (finite impulse response) filter unit 36, a subtraction unit 37, a quadrature modulation unit (QMOD) 38, a D / A conversion unit 39, and a BPF 40 are provided. The signal processing between the quadrature demodulating unit 23 and the quadrature modulating unit 38 is all complex signal processing. Therefore, the signal path is drawn with a single line on the block diagram, but the actual part is actually shown. Signal processing using both the signal and the imaginary part signal is performed.

  The interference wave extraction device 1-1 is a desired wave that is affected by interference of other terrestrial digital broadcast waves of the ISDB-T method that employs OFDM (Orthogonal Frequency Division Multiplexing) as a transmission method. Terrestrial digital broadcast waves are received, and the received signal is converted into an IF (Intermediate Frequency) signal. Then, the interference wave extracting apparatus 1-1 extracts the mobile reception modulated wave signal (A layer signal) transmitted in the A layer of the desired terrestrial digital broadcast wave from the IF signal, and converts it into the extracted A layer signal. Equalization and symbol determination are performed on the signal to extract a desired wave signal, a transmission path characteristic is added to generate a replica (duplicate) signal, which is generated from an original signal (IF signal) on which an interference wave is superimposed. Subtract and output an interference wave signal as a result of the subtraction. Thus, using the fact that the reception level of the desired wave is higher than the reception level of the interference wave, a replica signal of the A layer signal of the desired wave is generated, and only the desired wave signal is removed by subtracting from the received signal. be able to. As a result, only the signal spectrum of the desired wave disappears, and it becomes possible to receive and observe the portable reception signal wave (interference wave) transmitted in the A layer of the ISDB-T interference wave.

  The BPF 21 receives an IF signal in which a desired wave and an interference wave are mixed, and extracts an A layer signal in a predetermined frequency range based on the center frequency from the IF signal. The BPF 21 is configured by, for example, a SAW (Surface Acoustic Wave) filter. The A layer signal extracted by the BPF 21 is a signal in a state where an interference wave is superimposed on a desired wave.

  The A / D conversion unit 22 converts the A layer signal extracted by the BPF 21 from an analog signal to a digital signal, and generates a sampled and digitized A layer signal. Thereby, the digital signal is processed from the orthogonal demodulator 23 to the D / A converter 39 in the subsequent stage.

  The orthogonal demodulator 23 orthogonally demodulates the A layer signal sampled and digitized by the A / D converter 22 and converts it into a complex OFDM signal of an equivalent low band.

  The synchronization reproduction unit 24 reproduces the synchronization of the complex OFDM signal generated by the orthogonal demodulation unit 23. Specifically, the synchronous reproduction unit 24 detects and reproduces the symbol timing from the guard interval correlation waveform, and generates a synchronization signal such as a symbol clock, an FFT clock, an FFT window timing, and a timing of a 4-symbol sequence of scattered pilots. Reproduce. Various reproduced timing signals are supplied to each part of the interference wave extracting apparatus 1-1 that requires them. Further, the synchronous reproduction unit 24 detects the frequency deviation of the complex OFDM signal from the guard interval correlation waveform and outputs it as frequency offset data. Synchronous reproduction of these OFDM signals using guard interval correlation is a known technique and will not be described in detail.

  Based on the symbol timing reproduced by the synchronous reproduction unit 24, the window processing unit 25 removes the GI from the complex OFDM signal generated by the orthogonal demodulation unit 23, and extracts a signal in an effective symbol period. Thereby, in the FFT unit 27 in the subsequent stage, a range to be fast Fourier transformed is specified.

  The delay unit 26 adds a delay corresponding to a processing time for generating a desired wave replica signal by the components from the window processing unit 25 to the FIR filter unit 36 to the complex OFDM signal generated by the orthogonal demodulation unit 23. Thereby, in the subtraction part 37, the timing which subtracts the desired wave replica signal from the complex OFDM signal in which the desired wave and the interference wave are mixed can be matched.

  The FFT unit 27 performs a fast Fourier transform process on the complex OFDM signal in the effective symbol period extracted by the window processing unit 25 to convert the time-domain complex OFDM signal into a frequency-domain carrier symbol for one segment.

  The SP signal extraction unit 28 extracts an SP signal that is a pilot signal transmitted as a carrier symbol having a predetermined symbol number and carrier number from the carrier symbols output from the FFT unit 27. The extracted SP signal is used to calculate transmission path characteristics.

  The transmission path characteristic calculation unit 29 converts an SP signal (reception SP signal) whose amplitude and phase are changed by transmission path distortion extracted by the SP signal extraction unit 28 into an SP signal (transmission SP) having a predetermined amplitude and phase. Signal)) to calculate the transmission path characteristics. Since the SP signal is discretely inserted in the symbol direction (time direction) and the carrier direction (frequency direction), the transmission path characteristics calculated from the SP signal are also discrete in the symbol direction and the carrier direction. Therefore, the channel characteristics for all carrier symbols are calculated by interpolating the calculated channel characteristics for the SP signal in the symbol direction and the carrier direction. There are various methods for the interpolation processing in the symbol direction and the carrier direction, and many of them are known techniques, so detailed description thereof will be omitted.

  The equalization unit 30 equalizes the carrier symbol output from the FFT unit 27 by complex division by the transmission path characteristic calculated by the transmission path characteristic calculation unit 29, thereby obtaining the amplitude and phase amount of the carrier symbol. Compensation will be provided. Thereby, the carrier symbol of the desired wave A layer signal from which the transmission path distortion is removed is obtained.

  The filter coefficient generation unit 31 performs an inverse fast Fourier transform process on the transmission line characteristic calculated by the transmission line characteristic calculation unit 29 to convert the frequency domain transmission line characteristic into a time domain impulse response. Based on the impulse response, a filter coefficient used in the FIR filter unit 36 is generated. Here, the FIR filter unit 36 is configured to reproduce the transmission path characteristic calculated by the transmission path characteristic calculation unit 29, and the filter coefficient generated by the filter coefficient generation unit 31 is transmitted to the transmission path in the FIR filter unit 36. Used to reproduce characteristics.

  The symbol determination unit 32 calculates a threshold value from the position of the signal point based on a predetermined mapping rule for the carrier symbol equalized by the equalization unit 30, and compares the threshold value to determine the signal point at the time of transmission. presume. If the carrier symbol modulation method is QPSK (Quadrature Phase Shift Keying) and the DU ratio of the interference wave to the desired wave is sufficiently large, hard decision can be used for the decision processing.

  Here, since the reception level of the desired wave is higher than the reception level of the interference wave (the amplitude of the interference wave is smaller than half of the distance between the signal points of the desired wave in the frequency domain), the symbol determination unit 32 estimates this. The signal point becomes the signal point at the time of transmitting the desired wave. Thereby, only the desired wave signal can be extracted in the frequency domain from the received signal in which the desired wave and the interference wave are mixed.

  The remodulation unit 33 performs remapping of carrier symbols based on the signal point information estimated by the symbol determination unit 32. Thereby, the carrier symbol at the time of transmission in the desired wave is reproduced.

  The IFFT unit 34 performs an inverse fast Fourier transform process on the carrier symbol of the desired wave that has been remapped by the remodulation unit 33, and for each OFDM symbol, converts the frequency domain carrier symbol into a complex in the time domain effective symbol period. Convert to OFDM signal.

  The GI adding unit 35 converts the GI having a length defined in the ISDB-T transmission scheme to the complex OFDM signal of the effective symbol period, which is converted by the IFFT unit 34 and output, and Add to the leading edge. Accordingly, a desired wave signal in the time domain that does not include transmission path distortion is generated.

  The FIR filter unit 36 uses the filter coefficient generated by the filter coefficient generation unit 31 to change the transmission path characteristic with respect to the complex OFDM signal of the desired wave that does not include the transmission path distortion in the time domain to which the GI is added by the GI addition unit 35. In addition, it is adjusted so as to have the same amplitude characteristic and phase characteristic as the desired wave included in the received signal. Thereby, the adjusted signal becomes a replica signal of the A layer of the desired wave.

  The subtracting unit 37 subtracts the desired wave replica signal adjusted and output by the FIR filter unit 36 from the complex OFDM signal delayed by the delay unit 26 (a signal in which the desired wave and the interfering wave are mixed). Extract only. As a result, the desired wave is canceled. That is, the signal after subtraction is only the A layer signal of the interference wave with the desired wave canceled.

  The quadrature modulation unit 38 performs quadrature modulation on the complex OFDM signal, which is the A layer signal of the interference wave extracted by the subtraction unit 37, and converts it into an IF signal of the interference wave.

  The D / A converter 39 converts the IF signal of the interference wave converted by the quadrature modulator 38 from a digital signal to an analog signal, and generates an analog IF signal.

  The BPF 40 removes the aliasing component from the spectrum that appears in the IF signal converted by the D / A converter 39. The BPF 40 may use an LPF (Low Pass Filter) instead of a BPF (Band Pass Filter). As a result, an IF signal of an interference wave is output.

  As described above, according to the interference wave extracting apparatus 1-1 of the first embodiment, a signal in which a desired wave and an interference wave are mixed is received, and the BPF 21 extracts the A layer signal from the IF signal of the received signal and performs orthogonal demodulation. The unit 23 performs quadrature demodulation of the A layer signal, the FFT unit 27 performs fast Fourier transform to convert it to frequency domain carrier symbols, the equalization unit 30 divides and equalizes the carrier symbols by the transmission path characteristics, and the symbol determination unit 32 determines the symbol and uses the fact that the reception level of the desired wave is higher than the reception level of the interference wave, thereby estimating the signal at the transmission point of the desired wave, the remodulation unit 33 remapping, and the IFFT unit 34 Is subjected to inverse fast Fourier transform to generate a signal in the time domain, and the GI adding unit 35 adds the GI to generate a desired wave signal in the time domain. Further, the transmission line characteristic calculation unit 29 calculates the transmission line characteristic using the SP signal extracted from the carrier symbol, and the filter coefficient generation unit 31 generates the filter coefficient from the transmission line characteristic. Further, the FIR filter unit 36 adds a transmission path characteristic to the desired wave signal in the time domain, and generates a desired wave replica signal. Further, the subtracting unit 37 subtracts the desired wave replica signal from the signal in which the desired wave and the interference wave are mixed, cancels the desired wave signal and extracts the interference wave signal, the quadrature modulation unit 38 performs the quadrature modulation, and the BPF 40 Removed the folding component.

  Thus, even in a situation where the desired wave and the interference wave are mixed, the desired signal can be extracted by utilizing the fact that the reception level of the desired wave is higher than the reception level of the interference wave. The desired wave signal can be removed from the signal, and the interference wave signal can be extracted with high accuracy. Therefore, it is possible to extract the interference wave without stopping the transmitter of the transmitting station and stop the desired wave, and it is possible to investigate the extracted interference wave, thereby reducing the work load of the broadcaster It becomes.

  Next, an interference wave extracting apparatus according to the second embodiment will be described. FIG. 3 is a block diagram illustrating a configuration of an interference wave extraction apparatus according to the second embodiment. The interference wave extraction device 1-2 includes a BPF 21, an A / D conversion unit 22, an orthogonal demodulation unit 23, a synchronous reproduction unit 24, a window processing unit 25, a delay unit 26, an FFT unit 27, an SP signal extraction unit 28, and a transmission path. Characteristic calculation unit 29, equalization unit 30, filter coefficient generation unit 31, symbol determination unit 32, remodulation unit 33, IFFT unit 34, GI addition unit 35, FIR filter unit 36, subtraction unit 37, orthogonal modulation unit 38, D / A conversion part 39, BPF40, SP signal generation part 41, and SP signal change part 42 are provided. The signal processing between the quadrature demodulating unit 23 and the quadrature modulating unit 38 including the SP signal generating unit 41 and the SP signal changing unit 42 is all complex signal processing. The signal path is drawn in FIG. 1, but in actuality, signal processing using both real part signals and imaginary part signals is performed.

  When comparing the interference wave extraction device 1-1 of the first embodiment shown in FIG. 2 with the interference wave extraction device 1-2 of the second embodiment shown in FIG. This is the same in that it includes the components of the interference wave extraction device 1-1 shown in FIG. On the other hand, the interference wave extraction device 1-2 of the second embodiment includes an SP signal generation unit 41 and an SP signal switching unit 42 in addition to the configuration of the interference wave extraction device 1-1 of the first embodiment. This is different from the interference wave extraction device 1-1 of the first embodiment. The SP signal generating unit 41 and the SP signal changing unit 42 are provided after the remodulation unit 33 and before the IFFT unit 34. In FIG. 3, the same reference numerals as those in FIG.

  The interference wave extraction device 1-2 receives the terrestrial digital broadcast wave of the desired wave that is affected by the interference of other digital terrestrial broadcast waves, and converts the ISDB-T received signal into an IF signal. Then, the interference wave extraction device 1-2 extracts the A layer signal from the IF signal, converts the extracted A layer signal into a frequency domain signal, performs equalization and symbol determination, extracts the desired wave signal, and determines in advance. The SP signal inserted at the position of the specified symbol number and carrier number is replaced with an error-free SP signal that has been generated separately, further added with transmission path characteristics, and a new desired wave replica signal is generated and crosstalked. Subtract from the original signal (IF signal) on which the wave is superimposed, and output an interference wave signal as a subtraction result.

  The SP signal generator 41 generates an SP signal having a predetermined amplitude and phase, that is, an SP signal whose amplitude and phase at the time of transmission are known.

  The SP signal changing unit 42 uses the SP signal generating unit 41 to convert the SP signal inserted at the position of the predetermined symbol number and carrier number in the carrier symbol of the desired wave remapped by the remodulating unit 33. Replace with the generated SP signal. By this operation, the reproduced SP signal that may have caused a determination error at the time of symbol determination included in the original signal is replaced with an SP signal that is generated separately and has no error.

  Then, IFFT unit 34 performs inverse fast Fourier transform processing on the carrier symbol of the desired wave whose SP signal has been replaced by SP signal adding unit 42.

  As described above, according to the interference wave extraction device 1-2 of the second embodiment, the symbol determination unit 32 performs symbol determination and uses that the reception level of the desired wave is higher than the reception level of the interference wave. The signal of the desired wave transmission point is estimated, the carrier wave of the desired wave without transmission path distortion is reproduced, and the SP signal replacement unit 42 of the desired wave reproduces the SP signal of the reproduced carrier symbol of the desired wave. The SP signal is generated separately. Further, the FIR filter unit 36 adds the transmission path characteristic in the time domain to the desired wave signal after the SP signal is replaced, and generates the desired wave replica signal. Further, the subtracting unit 37 cancels the desired wave signal from the signal in which the desired wave and the interference wave are mixed, and extracts only the interference wave signal.

  Thus, even in a situation where the desired wave and the interference wave are mixed, the desired signal can be extracted by utilizing the fact that the reception level of the desired wave is higher than the reception level of the interference wave. The desired wave signal can be removed from the signal, and the interference wave signal can be extracted with high accuracy. Therefore, it is possible to extract the interference wave without stopping the transmitter of the transmitting station and stop the desired wave, and it is possible to investigate the extracted interference wave, thereby reducing the work load of the broadcaster It becomes. In addition, since the SP signal is replaced in the carrier symbol of the desired wave after re-modulation, even if there is an error in the symbol determination of the SP signal in the symbol determination unit 32, the error can be corrected. That is, the accuracy of the desired wave replica signal can be increased, and the accuracy of the interference wave signal obtained by removing the desired wave signal from the received signal can also be increased.

  Next, an interference wave extracting apparatus according to the third embodiment will be described. FIG. 4 is a block diagram illustrating the configuration of the interference wave extraction apparatus according to the third embodiment. This interference wave extraction device 1-3 includes a BPF 21, an A / D conversion unit 22, an orthogonal demodulation unit 23, a synchronous reproduction unit 24, a window processing unit 25, a delay unit 26, an FFT unit 27, an SP signal extraction unit 28, a transmission path Characteristic calculation unit 29, equalization unit 30, filter coefficient generation unit 31, symbol determination unit 32, remodulation unit 33, IFFT unit 34, GI addition unit 35, FIR filter unit 36, subtraction unit 37, orthogonal modulation unit 38, D / A conversion part 39, BPF40, SP signal generation part 41, SP signal change part 42, and BPF43 are provided. The signal processing between the quadrature demodulating unit 23 and the quadrature modulating unit 38 including the SP signal generating unit 41, the SP signal changing unit 42, and the BPF 43 is all complex signal processing. Although the signal path is drawn by the line, the signal processing by both the real part signal and the imaginary part signal is actually performed.

  When comparing the interference wave extraction device 1-2 of the second embodiment shown in FIG. 3 and the interference wave extraction device 1-3 of the third embodiment shown in FIG. 4, both devices 1-2 and 1-3 are shown in FIG. 3 is the same in that it includes the components of the interference wave extraction device 1-2 shown in FIG. On the other hand, the interference wave extraction device 1-3 of the third embodiment is further provided with a BPF 43 in addition to the configuration of the interference wave extraction device 1-2 of the second embodiment. It is different from 1-2. In FIG. 4, the BPF 43 is provided after the orthogonal demodulation unit 23 and before the window processing unit 25 and the delay unit 26. In FIG. 4, the same reference numerals as those in FIG.

  The interference wave extraction device 1-3 receives a terrestrial digital broadcast wave of a desired wave that is affected by interference of other terrestrial digital broadcast waves, and converts the ISDB-T received signal into an IF signal. Then, the interference wave extracting apparatus 1-3 extracts the A layer signal from the IF signal using an analog filter, further extracts the A layer signal strictly using a digital filter, converts the extracted A layer signal into a frequency domain signal, etc. And a symbol determination are performed to extract a desired wave signal, and an SP signal inserted at a position of a predetermined symbol number and carrier number is replaced with a separately generated SP signal without error, and further, transmission path characteristics Is added, a desired wave replica signal is newly generated, and it is subtracted from the original signal (IF signal) on which the interference wave is superimposed, and an interference wave signal as a subtraction result is output.

  The BPF 43 is composed of a digital filter having a steep shoulder characteristic, and extracts the A layer signal from the complex OFDM signal generated by the orthogonal demodulation unit 23. Since the BPF 43 is configured by a digital filter, unlike the BPF 21 configured by an analog filter, only the A layer signal can be extracted strictly and with high accuracy.

  Then, based on the symbol timing reproduced by the synchronous reproduction unit 24, the window processing unit 25 removes the GI from the complex OFDM signal of the A layer signal extracted by the BPF 43, and extracts a signal in the effective symbol period. In addition, the delay unit 26 delays the processing time for generating a desired wave replica signal by the components from the window processing unit 25 to the FIR filter unit 36 to the complex OFDM signal of the A layer signal extracted by the BPF 43. Add.

  As described above, according to the interference wave extracting apparatus 1-3 of the third embodiment, the BPF 43 configured by the digital filter extracts the A layer signal with high accuracy, and the symbol determination unit 32 performs the carrier symbol of the A layer signal. By using the fact that the reception level of the desired wave is higher than the reception level of the interference wave, the signal at the transmission point of the desired wave is estimated, and the carrier symbol of the desired wave without transmission path distortion is reproduced. The SP signal changing unit 42 for the desired wave replaces the SP signal in the reproduced carrier symbol of the desired wave with a separately generated SP signal. Further, the FIR filter unit 36 adds the transmission path characteristic in the time domain to the desired wave signal after the SP signal is replaced, and generates the desired wave replica signal. Further, the subtracting unit 37 cancels the desired wave signal from the signal in which the desired wave and the interference wave are mixed, and extracts only the interference wave signal.

  Thus, even in a situation where the desired wave and the interference wave are mixed, the desired signal can be extracted by utilizing the fact that the reception level of the desired wave is higher than the reception level of the interference wave. The desired wave signal can be removed from the signal, and the interference wave signal can be extracted with high accuracy. Therefore, it is possible to extract the interference wave without stopping the transmitter of the transmitting station and stop the desired wave, and it is possible to investigate the extracted interference wave, thereby reducing the work load of the broadcaster It becomes. In addition, since the SP signal is replaced in the carrier symbol of the desired wave after re-modulation, even if there is an error in the symbol determination of the SP signal in the symbol determination unit 32, the error can be corrected. That is, the accuracy of the desired wave replica signal can be increased, and the accuracy of the interference wave signal obtained by removing the desired wave signal from the received signal can also be increased. Further, since the A layer signal is extracted with high accuracy by the digital filter, the desired wave signal can be extracted with high accuracy, and as a result, the accuracy of the interference wave signal can be further increased.

  Next, an interference wave extracting apparatus according to the fourth embodiment will be described. FIG. 5 is a block diagram illustrating a configuration of an interference wave extraction apparatus according to the fourth embodiment. This interference wave extraction device 1-4 includes a BPF 21, an A / D conversion unit 22, an orthogonal demodulation unit 23, a synchronous reproduction unit 24, a window processing unit 25, a delay unit 26, an FFT unit 27, an SP signal extraction unit 28, a transmission path Characteristic calculation unit 29, equalization unit 30, filter coefficient generation unit 31, symbol determination unit 32, remodulation unit 33, IFFT unit 34, GI addition unit 35, FIR filter unit 36, subtraction unit 37, orthogonal modulation unit 38, D / A converter 39, BPF 40, SP signal generator 41, SP signal switching unit 42, BPF 43, and AFC (Automatic Frequency Control) unit 44. The signal processing between the quadrature demodulation unit 23 and the quadrature modulation unit 38 including the SP signal generation unit 41, the SP signal switching unit 42, the BPF 43, and the AFC (Automatic Frequency Control) unit 44 are all performed. Since it is complex signal processing, the signal path is drawn with a single line on the block diagram, but in reality, signal processing is performed using both real part signals and imaginary part signals.

  When comparing the interference wave extracting apparatus 1-3 of the third embodiment shown in FIG. 4 with the interference wave extracting apparatus 1-4 of the fourth embodiment shown in FIG. 4 is the same in that it includes the components of the interference wave extraction device 1-3 shown in FIG. On the other hand, the interference wave extracting apparatus 1-4 according to the fourth embodiment further includes an AFC unit 44 in addition to the configuration of the interference wave extracting apparatus 1-3 according to the third embodiment. It differs from the extraction device 1-3. In FIG. 5, the AFC unit 44 is provided after the orthogonal demodulation unit 23 and before the BPF 43 and the synchronous reproduction unit 24. In FIG. 5, the same reference numerals as those in FIG.

  The interference wave extraction device 1-4 receives the terrestrial digital broadcast wave of the desired wave that is affected by the interference of other terrestrial digital broadcast waves, and converts the ISDB-T received signal into an IF signal. Then, the interference wave extracting apparatus 1-4 extracts the A layer signal from the IF signal by an analog filter, removes the frequency offset of the complex OFDM signal of the A layer in the equivalent low band by automatic frequency control, and further, the A layer signal Is strictly extracted by a digital filter, the extracted A layer signal is converted into a frequency domain signal, equalization and symbol determination are performed to extract a desired wave signal, and the signal is inserted at a predetermined symbol number and carrier number position. The SP signal is replaced with an error-free SP signal that is generated separately, transmission path characteristics are added, a desired replica signal is newly generated, and the original signal (IF signal) on which the interference wave is superimposed Is subtracted from the signal, and an interference signal as a result of the subtraction is output.

  FIG. 6 is a block diagram showing a configuration of the AFC unit 44 shown in FIG. The AFC unit 44 includes an NCO (Numerally Controlled Oscillator) control data generator 442, an NCO 443, and a phase rotator 441. The phase rotator 441 includes four multipliers 444-1 to 444-4, a subtractor 445, and an adder 446. The NCO control data generator 442 receives the frequency offset data detected and output by the synchronous reproduction unit 24, and generates NCO control data that changes according to data having an offset opposite to the frequency offset data. The NCO 443 receives the NCO control data generated by the NCO control data generator 442, generates a signal whose frequency increases or decreases according to the NCO control data, and outputs the signal to the phase rotator 441. Thereby, the NCO 443 can output the I-axis signal and the Q-axis signal of the complex carrier signal having an offset opposite to the frequency offset to the phase rotator 441.

  The multiplier 444-1 of the phase rotator 441 receives the I-axis signal of the complex OFDM signal from the quadrature demodulator 23 and the I-axis signal having the reverse frequency offset from the NCO 443, and multiplies both signals. The multiplier 444-2 receives the I-axis signal of the complex OFDM signal from the quadrature demodulator 23 and the Q-axis signal having the reverse frequency offset from the NCO 443, and multiplies both signals. The multiplier 444-3 receives the Q-axis signal of the complex OFDM signal from the quadrature demodulator 23 and also receives the Q-axis signal having a reverse frequency offset from the NCO 443, and multiplies both signals. Multiplier 444-4 receives the Q-axis signal of the complex OFDM signal from quadrature demodulator 23 and also receives the I-axis signal having the reverse frequency offset from NCO 443, and multiplies both signals. The subtractor 445 subtracts the multiplication result of the multiplier 444-3 from the multiplication result of the multiplier 444-1, and outputs the subtraction result to the BPF 43 as an I-axis signal of the complex OFDM signal from which the frequency offset is removed. The adder 446 adds the multiplication result of the multiplier 444-2 and the multiplication result of the multiplier 444-4, and outputs the addition result to the BPF 43 as a Q-axis signal of the complex OFDM signal from which the frequency offset is removed.

  That is, the AFC unit 44 inputs the complex OFDM signal input from the quadrature demodulation unit 23 to the phase rotator 441 as a multiplied signal, and also inputs the frequency offset data detected and output by the synchronous reproduction unit 24. Then, the AFC unit 44 causes the NCO 443 to generate a complex carrier signal having an inverse frequency offset based on the frequency offset data, and uses the complex carrier signal having the inverse frequency offset generated by the NCO 443 as a multiplication signal. By inputting a reverse frequency offset to the complex OFDM signal input to the rotator 441 and input from the orthogonal demodulation unit 23, a complex OFDM signal from which the frequency offset has been removed is generated.

  The BPF 43 is composed of a digital filter having steep shoulder characteristics, and extracts the A layer signal from the complex OFDM signal after the frequency offset removal generated by the AFC unit 44.

(Necessity of AFC Department)
As described above, the AFC unit 44 removes the frequency offset of the complex OFDM signal generated by the orthogonal demodulation unit 23. Hereinafter, the effect obtained by removing the frequency offset of the complex OFDM signal in the interference wave extracting apparatus 1-4, that is, the necessity of the AFC unit 44 will be described in detail.

  The quadrature demodulator 23 of the interference wave extraction apparatus 1-4 multiplies an IF signal in the IF band composed of a number of carriers by a complex local signal having a known constant frequency (the center frequency of the IF signal), and then LPF ( Low Pass Filter) processing is performed to remove image components and generate an equivalent low-band complex OFDM signal.

  As described above, when an OFDM signal in the IF band is converted into a complex OFDM signal in the equivalent low band, an IF band carrier signal having a constant frequency is used. The frequency of the IF band carrier signal must exactly match the carrier frequency of the input IF band OFDM signal. However, if a deviation (offset) occurs between the frequency of the carrier signal and the frequency of the input OFDM signal in the IF band, FFT is performed with the orthogonality between the carriers broken, Inter-carrier interference occurs in the carrier symbol, and the error rate characteristic after demodulation is degraded.

Here, the relationship between the frequency offset and the error rate characteristic will be described. When the symbol rate of the OFDM signal is T _S and the symbol frequency is f ₀ , when there is no GI, the relationship between the symbol rate T _S and the symbol frequency f ₀ is expressed by f ₀ = 1 / T _S. If the OFDM signal, the inverse of the symbol rate _{T S} corresponds to the carrier spacing frequency. The magnitude of the frequency offset normalized by the carrier interval is defined by α and is called a normalized frequency offset. The greater the normalized frequency offset α, the greater the frequency offset, expressed as α = Δf / f ₀ .

  FIG. 7 is a diagram showing the characteristic of the symbol error rate with respect to the received CN ratio when there is a frequency offset. In FIG. 7, the characteristic of the normalized frequency offset α = 0 indicates a characteristic when there is no frequency offset and only Gaussian noise is present. As can be seen from FIG. 7, when the normalized frequency offset α is increased, the improvement in error rate is degraded even if the CN ratio is improved. In particular, in the example of 64QAM adopted in ISDB-T, when the frequency offset is increased, no improvement in the error rate is observed no matter how the CN ratio is improved. This is because the influence of inter-carrier interference due to the frequency offset becomes dominant.

  FIG. 8 is a diagram illustrating a symbol error rate with respect to a normalized frequency offset. As can be seen from FIG. 8, the symbol error rate due to interference rapidly deteriorates as the normalized frequency offset α increases. 7 and 8 are quoted from "" An easy-to-understand OFDM technology ", Makoto Itami, Ohmsha.

  As described above, since the presence of the frequency offset greatly affects the quality of the demodulation result of the OFDM signal, the complex OFDM signal without the frequency offset can be generated by providing the AFC unit 44 shown in FIG. Is required.

  In addition, by providing the AFC unit 44, it is possible to make the pass bandwidth of the BPF 43 closer to the bandwidth of the A layer signal by accurately removing the frequency offset of the complex OFDM signal input to the BPF 43, and more accurately. It is possible to extract the interference wave signal well.

  Note that the method for realizing the AFC function shown in FIG. 6 is an example, and there are various other methods. However, since many of them are known techniques, the description thereof is omitted here. In short, it is only necessary to generate a complex OFDM signal from which a frequency offset has been removed by the AFC function. In the above-described interference wave extracting apparatuses 1-1 to 1-3 described in the first to third embodiments, the frequency of the input IF signal exactly matches the specified value, and the complex low-band complex OFDM signal It is assumed that the frequency offset is zero.

  As described above, according to the interference wave extraction device 1-4 of the fourth embodiment, the AFC unit 44 removes the frequency offset of the complex OFDM signal, and the BPF 43 configured by the digital filter converts the A layer signal with high accuracy. The symbol determination unit 32 performs symbol determination on the carrier symbol of the A layer signal, and uses the fact that the reception level of the desired wave is higher than the reception level of the interference wave, thereby estimating the signal at the transmission point of the desired wave Then, the carrier symbol of the desired wave having no transmission path distortion is reproduced, and the SP signal assigning unit 42 of the desired wave substitutes the SP signal among the reproduced carrier symbols of the desired wave to the SP signal generated separately. . Further, the FIR filter unit 36 adds the transmission path characteristic in the time domain to the desired wave signal after the SP signal is replaced, and generates the desired wave replica signal. Further, the subtracting unit 37 cancels the desired wave signal from the signal in which the desired wave and the interference wave are mixed, and extracts only the interference wave signal.

  Thus, even in a situation where the desired wave and the interference wave are mixed, the desired signal can be extracted by utilizing the fact that the reception level of the desired wave is higher than the reception level of the interference wave. The desired wave signal can be removed from the signal, and the interference wave signal can be extracted with high accuracy. Therefore, it is possible to extract the interference wave without stopping the transmitter of the transmitting station and stop the desired wave, and it is possible to investigate the extracted interference wave, thereby reducing the work load of the broadcaster It becomes. In addition, since the SP signal is replaced in the carrier symbol of the desired wave after re-modulation, even if there is an error in the symbol determination of the SP signal in the symbol determination unit 32, the error can be corrected. That is, the accuracy of the desired wave replica signal can be increased, and the accuracy of the interference wave signal obtained by removing the desired wave signal from the received signal can also be increased. Further, since the A layer signal is extracted with high accuracy by the digital filter, the desired wave signal can be extracted with high accuracy, and as a result, the accuracy of the interference wave signal can be further increased. Further, since the frequency offset is removed from the signal converted into the equivalent low-frequency band, the desired wave can be extracted from the complex ODFM signal without the frequency offset, and as a result, the accuracy of the desired wave replica signal is increased. Therefore, the accuracy of the interference wave signal obtained by canceling the desired wave from the signal in which the desired wave and the interference wave are mixed can be further increased.

  Next, an interference wave extracting apparatus according to the fifth embodiment will be described. FIG. 9 is a block diagram illustrating a configuration of an interference wave extraction device according to the fifth embodiment. This interference wave extraction device 1-5 includes a BPF 21, an A / D conversion unit 22, an orthogonal demodulation unit 23, a synchronous reproduction unit 24, a window processing unit 25, a delay unit 26, an FFT unit 27, an SP signal extraction unit 28, a transmission path Characteristic calculation unit 29, equalization unit 30, filter coefficient generation unit 31, IFFT unit 34, GI addition unit 35, FIR filter unit 36, subtraction unit 37, quadrature modulation unit 38, D / A conversion unit 39, BPF 40, 43, AFC unit 44, data symbol separation unit 45, frequency deinterleaving unit 46, time deinterleaving unit 47, demapping unit 48, bit deinterleaving unit 49, depuncture unit 50, Viterbi decoding unit 51, convolutional coding unit 52, puncture 53, bit interleave unit 54, mapping unit 55, time interleave unit 56, frequency interleave unit 57, symbol format And a: (Continuous al pilot Continual Pilot) signal generator 61 and the frame reconstruction unit 62 section 58, re-modulation unit 59, delay unit 60, SP / CP. Of the signal processing from the orthogonal demodulator 23 to the orthogonal modulator 38, the bit deinterleaver 49, the depuncture unit 50, the Viterbi decoder 51, the convolutional encoder 52, the puncture unit 53, and the bit interleaver 54 Since all parts except for are complex signal processing, the signal path is drawn with a single line on the block diagram, but in reality, signal processing is performed with both real part signals and imaginary part signals. Yes.

  When comparing the interference wave extraction device 1-4 of the fourth embodiment shown in FIG. 5 and the interference wave extraction device 1-5 of the fifth embodiment shown in FIG. 9, the interference wave extraction device 1-5 shown in FIG. , Instead of the components from the symbol determination unit 32 to the SP signal generation unit 41 and the SP signal replacement unit 42 in the interference wave extraction apparatus 1-4 shown in FIG. 5, the data symbol separation unit 45 to the frame reconstruction unit 62 It differs in the point provided with. In FIG. 9, the same reference numerals as those in FIG.

  Interference wave extraction apparatus 1-5 receives the terrestrial digital broadcast wave of the desired wave that is affected by the interference of other terrestrial digital broadcast waves, and converts the received signal into an IF signal. Then, the interference wave extracting apparatus 1-5 extracts the A layer signal from the IF signal by an analog filter, removes the frequency offset of the complex OFDM signal of the A layer in the equivalent low band by automatic frequency control, and further, the A layer signal Are extracted with a digital filter, the extracted A layer signal is converted into a frequency domain signal, equalization is performed, and among all carrier symbols, AC (Auxiliary Channel) and TMCC (Transmission and Multiplexing Configuration Control) signals are generated. It is separated into carrier symbols that are transmitted, carrier symbols that are transmitting SP and CP signals, and carrier symbols that are transmitting other data signals. Then, the interference wave extraction apparatus 1-5 performs demultiplexing on the frequency and time axes in carrier symbol units for carrier symbols transmitting data signals other than carrier symbols transmitting AC, TMCC, SP, and CP signals. Interleave, then demapping, bit deinterleave and depuncture processing, bit error correction of inner code by viterbi decoding, convolutional coding, puncture processing, bit interleaving and symbol remapping Then, interleaving on the time and frequency axes is performed in units of carrier symbols. Then, the interference wave extraction apparatus 1-5 adds the AC and TMCC signals separately hard-decisioned and remapped to the interleaved signal and the SP and CP signals without errors generated separately to reconstruct the OFDM frame. Then, IFFT and GI addition processing is performed to convert the signal into a time domain signal, and then a desired wave replica signal is newly generated by adding transmission path characteristics, and the original signal (IF Subtraction from the signal), and outputs an interference signal as a result of the subtraction.

  The data symbol separation unit 45 includes carrier symbols, SP, and CP that transmit AC and TMCC signals among the carrier symbols of the A layer signal of ISDB-T corrected by the equalization unit 30 using the channel response. A carrier symbol transmitting a signal and a carrier symbol transmitting another data signal are separated. The carrier symbols transmitting the separated AC and TMCC signals are sent to the symbol determination unit 58, and the carrier symbols transmitting the data signals are sent to the frequency deinterleaving unit 46.

  The frequency deinterleaving unit 46 eliminates the interleaving on the frequency axis of the data symbol applied to randomize the burst error due to multipath according to a predetermined rule. Specifically, carrier rotation and carrier randomization within the data segment are eliminated. Since the rule for solving the interleaving is known, the description is omitted here. For details, see the aforementioned Non-Patent Document 1. Hereinafter, unless stated otherwise, the expression “according to a predetermined rule” or “predetermined rule” means that the rule described in Non-Patent Document 1 is followed.

  Since the carrier symbol transmitted by time interleaving is given a different delay on the time axis for each carrier, the time deinterleaving unit 47 eliminates the delay difference for each carrier according to a predetermined rule. This operation is performed in units of data segments.

  The demapping unit 48 estimates the transmission symbol from the position on the I and Q planes of the received transmission symbol in accordance with the modulation scheme of the carrier transmitting the A layer signal, and performs 0, 1 bit data or subsequent Viterbi decoding When the unit 51 performs a soft decision, a likelihood expressed by about 3 bits is generated for each bit.

  Bit data or likelihood data generated by the demapping unit 48 is subjected to bit interleaving in order to randomize consecutive bit errors caused by symbol errors. The bit deinterleave unit 49 eliminates this randomization according to a predetermined rule.

  In the inner code encoding unit of ISDB-T, in order to correspond to a plurality of coding rates with one mother code, data bits are regularly thinned according to a prescribed puncture pattern. The depuncture unit 50 inserts provisional bit data or likelihood = 0.5 into the bit data thinned out according to the inner coding rate of the A layer or the likelihood data that does not exist at the time of inner code decoding.

  The Viterbi decoding unit 51 performs Viterbi decoding, which is inner code decoding, using the output bit data or likelihood information from the depuncture unit 50. As a result, the Viterbi decoding unit 51 outputs the data bits after the inner code correction.

  The convolutional encoding unit 52 performs error correction original encoding on the data bits using an inner code. The coding rate is the same as the received A layer signal. The encoding rate and constraint length of the encoder for performing the original encoding follow predetermined rules.

  The puncture unit 53 performs data bit thinning according to a prescribed puncture pattern according to the inner coding rate of the A layer transmission. The bit interleaving unit 54 performs bit interleaving on the bit string output from the puncture unit 53 according to a predetermined rule.

  The mapping unit 55 performs symbol mapping of QPSK modulation on the bit string after bit interleaving according to a predetermined rule. The data after mapping is complex symbol data having values on the I axis and the Q axis. The time interleaving unit 56 performs time interleaving on the mapped continuous symbol data according to a predetermined rule. The frequency interleaving unit 57 performs randomization in the frequency axis direction on the carriers in the segment transmitted in the A layer according to a predetermined rule.

  The symbol determination unit 58 transmits the BPSK modulation carrier transmitting the AC and TMCC signals separated by the data symbol separation unit 45 by threshold processing based on a mapping rule determined in advance from the position of the signal point of the reception signal. Estimate the time signal point and obtain the transmitted symbol. Since symbols transmitting AC and TMCC signals are BPSK-modulated, if there is a sufficient DU ratio of interference waves, hard decision can be used for threshold processing, that is, symbol decision.

  Based on the position of the transmission symbol determined and estimated by the symbol determination unit 58, the remodulation unit 59 generates I-axis and Q-axis data representing the position of the signal point on the I and Q planes.

  As described above, the data symbol separation unit 45 separates the carrier symbol of the AC and TMCC signals, the carrier symbol of the SP and CP signals, and the carrier symbol of the data signal, and the carrier symbol of the data signal is separated from the frequency deinterleaving unit 46. To the frequency interleaving unit 57, the processing time is longer than the processing time of the processing on the carrier symbols of the AC and TMCC signals (processing from the symbol determination unit 58 to the remodulation unit 59). For this reason, the delay unit 60 adds a delay to the carrier symbols of the remapped AC and TMCC signals in order to fill the difference in processing time. The SP / CP signal generator 61 generates an error-free SP signal and CP signal. Specifically, an SP signal and a CP signal having a predetermined amplitude and phase, that is, an SP signal and a CP signal whose amplitude and phase at the time of transmission are known are generated.

  The frame reconstruction unit 62 uses predetermined rules for the carrier symbol of the data signal after frequency interleaving, the carrier symbol of the AC and TMCC signals, and the carrier symbol of the SP and CP signal without error generated by the SP / CP signal generation unit 61. To reconstruct the OFDM frame of the layer A segment.

  As described above, according to the interference wave extraction apparatus 1-5 of the fifth embodiment, the AFC unit 44 removes the frequency offset of the complex OFDM signal of the A layer in the equivalent low band, and further converts the A layer signal to the digital filter. Are extracted strictly by the BPF 43 constituted by the above, and the extracted A layer signal is converted into a frequency domain signal and equalized, and then in the data symbol separation unit 45, among the carrier symbols, the carrier symbols of the AC and TMCC signals, The carrier symbols of the SP and CP signals and the carrier symbols of the other data signals are separated, and the carrier symbols of the data signals excluding the carrier symbols of the AC, TMCC, SP, and CP signals are demultiplexed on the frequency and time axes. Interleave, then demap and bit deinterleave, depunct After performing bit error correction of the inner code by Viterbi decoding, convolutional coding, puncture processing, bit interleaving and symbol remapping are performed, and interleaving is performed on the time and frequency axes. Separately hard-decided and remapped carrier symbols of AC and TMCC signals and error-free SP and CP signal carrier symbols are added to reconstruct an OFDM frame, and further add channel characteristics after adding IFFT and GI Thus, a desired wave replica signal is newly generated and subtracted from the original signal (IF signal) on which the interference wave is superimposed, and only the interference wave signal as the subtraction result is extracted.

  Thus, even in a situation where the desired wave and the interference wave are mixed, the desired signal can be extracted by utilizing the fact that the reception level of the desired wave is higher than the reception level of the interference wave. The desired wave signal can be removed from the signal, and the interference wave signal can be extracted with high accuracy. Therefore, it is possible to extract the interference wave without stopping the transmitter of the transmitting station and stop the desired wave, and it is possible to investigate the extracted interference wave, thereby reducing the work load of the broadcaster It becomes. In addition, in the generation of the desired wave replica signal, error correction by the inner code is performed on the received desired wave data. Even if an error occurs in the symbol determination in the demapping unit 48 and a bit error occurs, The bit error can be corrected. In addition, since the SP and CP signals are replaced in the carrier symbol of the desired wave after remodulation, even if there is a symbol determination error in the SP and CP signals, the error can be corrected. That is, the accuracy of the desired wave replica signal can be increased, and the accuracy of the interference wave signal obtained by removing the desired wave signal from the received signal can also be increased. Further, since the A layer signal is extracted with high accuracy by the digital filter, the desired wave signal can be extracted with high accuracy, and as a result, the accuracy of the interference wave signal can be further increased. Further, since the frequency offset is removed from the signal converted into the equivalent low-frequency band, the desired wave can be extracted from the complex ODFM signal without the frequency offset, and as a result, the accuracy of the desired wave replica signal is increased. Therefore, the accuracy of the interference wave signal obtained by canceling the desired wave from the signal in which the desired wave and the interference wave are mixed can be further increased.

  Next, an interference wave extraction device according to Embodiment 6 will be described. FIG. 10 is a block diagram illustrating a configuration of an interference wave extraction apparatus according to the sixth embodiment. This interference wave extraction device 1-6 includes a BPF 21, an A / D conversion unit 22, an orthogonal demodulation unit 23, a synchronous reproduction unit 24, a window processing unit 25, a delay unit 26, an FFT unit 27, an SP signal extraction unit 28, a transmission path Characteristic calculation unit 29, equalization unit 30, filter coefficient generation unit 31, IFFT unit 34, GI addition unit 35, FIR filter unit 36, subtraction unit 37, quadrature modulation unit 38, D / A conversion unit 39, BPF 40, 43, AFC unit 44, data symbol separation unit 45, frequency deinterleaving unit 46, time deinterleaving unit 47, demapping unit 48, bit deinterleaving unit 49, depuncture unit 50, Viterbi decoding unit 51, convolutional coding unit 52, puncture 53, bit interleave unit 54, mapping unit 55, time interleave unit 56, frequency interleave unit 57, symbol format Unit 58, remodulation unit 59, delay unit 60, SP / CP signal generation unit 61, frame reconstruction unit 62, byte deinterleave unit 63, energy despreading unit 64, Reed-Solomon decoding unit 65, Reed-Solomon encoding unit 66 , An energy diffusing unit 67 and a byte interleaving unit 68 are provided. Of the signal processing from the orthogonal demodulator 23 to the orthogonal modulator 38, the bit deinterleaver 49, the depuncture unit 50, the Viterbi decoder 51, the byte deinterleaver 63, the energy despreader 64, and the Reed-Solomon decoding Since all of the parts except the unit 65, the Reed-Solomon encoding unit 66, the energy spreading unit 67, the byte interleaving unit 68, the convolutional encoding unit 52, the puncture unit 53, and the bit interleaving unit 54 are complex signal processing, a block diagram The signal path is drawn with a single line on the top, but in reality, signal processing is performed using both real part signals and imaginary part signals.

  When comparing the interference wave extracting apparatus 1-5 of the fifth embodiment shown in FIG. 9 and the interference wave extracting apparatus 1-6 of the sixth embodiment shown in FIG. 10, both apparatuses 1-5 and 1-6 are shown in FIG. 9 is the same in that it includes the components of the interference wave extraction device 1-5 shown in FIG. On the other hand, the interference wave extracting apparatus 1-6 of the sixth embodiment further includes components from the byte deinterleaving unit 63 to the byte interleaving unit 68 in addition to the configuration of the interference wave extracting apparatus 1-5 of the fifth example. Is different. In FIG. 10, components from the byte deinterleave unit 63 to the byte interleave unit 68 are provided after the Viterbi decoding unit 51 and before the convolutional coding unit 52. 10, parts common to those in FIG. 9 are denoted by the same reference numerals as those in FIG. 9, and detailed description thereof is omitted below.

  The interference wave extraction device 1-6 receives the terrestrial digital broadcast wave of the desired wave that is affected by the interference of other terrestrial digital broadcast waves, and converts the received signal into an IF signal. Then, the interference wave extracting apparatus 1-6 extracts the A layer signal from the IF signal by an analog filter, removes the frequency offset of the complex OFDM signal of the A layer in the equivalent low band by automatic frequency control, and further, the A layer signal Are strictly extracted by a digital filter, the extracted A layer signal is converted into a frequency domain signal, equalized, and then, among all carrier symbols, carrier symbols, SP and CP signals transmitting AC and TMCC signals Are separated into carrier symbols transmitting data and carrier symbols transmitting other data signals. Then, the interference wave extraction apparatus 1-6 demultiplexes the carrier symbols transmitting data signals other than the carrier symbols transmitting AC, TMCC, SP, and CP signals on the frequency and time axes in units of carrier symbols. After interleaving, demapping, bit deinterleaving, and depuncture processing, bit error correction of the inner code by viterbi decoding, byte deinterleaving and energy despreading are performed, and then the Reed Solomon that is the outer code. Decode the code to correct the byte error. Then, the interference wave extraction device 1-6 performs Reed-Solomon coding, energy diffusion, byte interleaving on the decoded data, performs convolution coding, puncture processing, bit interleaving, and symbol remapping, and performs carrier symbol units. To interleave on time and frequency axes. Then, the interference wave extraction apparatus 1-6 adds the AC and TMCC signals separately hard-decisioned and remapped to the interleaved signal and the SP and CP signals without errors generated separately to reconstruct the OFDM frame. Then, IFFT and GI addition processing is performed to convert the signal into a time domain signal, and then a desired wave replica signal is newly generated by adding transmission path characteristics, and the original signal (IF Subtraction from the signal), and outputs an interference signal as a result of the subtraction.

  The byte deinterleaving unit 63 converts the bit string after Viterbi decoding into a byte string, and performs byte deinterleaving according to a predetermined rule in units of bytes. The energy despreading unit 64 performs an exclusive OR operation on the bit-deinterleaved signal in bit units with the 15th order M-sequence PN signal and the data portion excluding the synchronization byte of the TS packet according to a predetermined rule. , Do energy despreading.

  The Reed-Solomon decoding unit 65 performs decoding of the shortened Reed-Solomon code RS (204, 188), which is outer code decoding, on the signal after energy despreading. The Reed-Solomon encoding unit 66 performs encoding of the shortened Reed-Solomon code RS (204, 188), which is outer code encoding, on the signal after Reed-Solomon decoding.

  The energy spreading unit 67 performs an exclusive OR operation on the 15-th order M-sequence PN code and the data portion excluding the synchronization byte of the TS packet for the signal after Reed-Solomon coding to perform energy spreading. Do. The byte interleaving unit 68 performs interleaving in units of bytes based on a predetermined rule to further extract the performance of the outer code with respect to the signal after energy spreading, and converts the obtained byte string into a bit string and outputs the bit string To do.

  As described above, according to the interference wave extracting apparatus 1-6 of the sixth embodiment, the bit error correction of the inner code is performed by the Viterbi decoding unit 51 in the same manner as the interference wave extracting apparatus 1-5 of the fifth embodiment. In addition, byte deinterleaving and energy despreading are performed, the Reed-Solomon code that is the outer code is decoded to correct byte errors, and Reed-Solomon coding, energy spreading, and byte interleaving are performed. Then, similar to the interference wave extraction apparatus 1-5 of the fifth embodiment, convolutional coding, puncture processing, bit interleaving and symbol remapping are performed, interleaving is performed on the time and frequency axes, and a hard decision is separately made. Then, the remapped AC and TMCC signal symbols and the error-free SP and CP signal symbols are added to reconstruct the OFDM frame, and after adding IFFT and GI, the desired wave replica signal is added. Is newly subtracted from the original signal (IF signal) on which the interference wave is superimposed, and only the interference wave signal as the subtraction result is extracted.

  Thereby, there exists an effect similar to the interference wave extraction apparatus 1-5 of Example 5. FIG. Therefore, similarly to the interference wave extraction device 1-5 of the fifth embodiment, the accuracy of the desired wave replica signal can be further increased, and the accuracy of the interference wave signal obtained by removing the desired wave signal from the received signal is further increased. Can be high.

  In the interference wave extracting devices 1-1 to 1-6 of the first to sixth embodiments, the BPF 21 extracts only the A layer signal and performs signal processing on the A layer signal as a whole device. On the other hand, the BPF 21 extracts the entire band of the OFDM signal including the A layer signal and the B layer signal, the A / D conversion unit 22, the orthogonal demodulation unit 23, the synchronous reproduction unit 24, the window processing unit 25, the delay unit 26, The FFT unit 27, the SP signal extraction unit 28, the transmission line characteristic calculation unit 29, the equalization unit 30, the filter coefficient generation unit 31, the FIR filter unit 36, and the BPF 43 perform signal processing on the entire band of the OFDM signal. Also good. In this case, the symbol determination unit 32 according to the first to fourth embodiments estimates a signal point at the time of transmission by hard determination with respect to the carrier symbol of the A layer signal among the carrier symbols of the entire band of the OFDM signal. A layer A signal of the wave is extracted, and the data symbol separation unit 45 of the fifth and sixth embodiments includes a carrier symbol that transmits the AC and TMCC signals of the layer A signal among the carrier symbols of all bands of the OFDM signal, The carrier symbols transmitting the SP and CP signals of the A layer signal and the carrier symbols transmitting the other data signals in the A layer signal are separated. And from the remodulation part 33 of Examples 1-4 to the GI addition part 35, signal processing is performed on the A layer signal in the same manner as described above. In addition, the frequency deinterleaving unit 46 and the symbol determination unit 58 to the GI addition unit 35 of the fifth and sixth embodiments perform signal processing on the A layer signal in the same manner as described above. The FIR filter unit 36 inputs the filter coefficients of the entire band from the filter coefficient generation unit 31 and also inputs the A layer signal of the desired wave from the GI addition unit 35, and performs the FIR filter process on the entire band. Further, the BPF 43 according to the third to sixth embodiments extracts the entire band of the OFDM signal including the A layer signal and the B layer signal by digital filter processing.

  Moreover, a normal computer can be used as a hardware configuration of the interference wave extraction apparatuses 1-1 to 1-6 of the first to sixth embodiments. The interference wave extracting devices 1-1 to 1-6 are configured by a computer including a CPU, a volatile storage medium such as a RAM, a non-volatile storage medium such as a ROM, an interface, and the like. Quadrature demodulation unit 23, window processing unit 25, delay unit 26, FFT unit 27, SP signal extraction unit 28, transmission path characteristic calculation unit 29, equalization unit 30, and filter coefficient generation unit provided in the interference wave extraction device 1-1 31, the symbol determination unit 32, the remodulation unit 33, the IFFT unit 34, the GI addition unit 35, the FIR filter unit 36, the subtraction unit 37, and the quadrature modulation unit 38 execute a program describing these functions to the CPU. This is realized by Further, components from the quadrature demodulation unit 23 to the quadrature modulation unit 38 included in the interference wave extraction device 1-2 (components similar to those of the interference wave extraction device 1-1), the SP signal generation unit 41, and the SP signal replacement Each function of the unit 42, components from the orthogonal demodulator 23 to the SP signal switching unit 42 included in the interference wave extraction device 1-3 (components similar to the interference wave extraction device 1-2), and each function of the BPF 43 In addition, each function of the components from the orthogonal demodulator 23 to the BPF 43 (components similar to those of the interference wave extraction device 1-3) and the AFC unit 44 included in the interference wave extraction device 1-4 also has these functions. Each is realized by causing the CPU to execute the described program. Further, the orthogonal demodulation unit 23, the synchronous reproduction unit 24, the window processing unit 25, the delay unit 26, the FFT unit 27, the SP signal extraction unit 28, the transmission path characteristic calculation unit 29, and the like included in the interference wave extraction device 1-5 are equalized. Unit 30, filter coefficient generation unit 31, IFFT unit 34, GI addition unit 35, FIR filter unit 36, subtraction unit 37, quadrature modulation unit 38, BPF 43, AFC unit 44, data symbol separation unit 45, frequency deinterleave unit 46, Time deinterleaving unit 47, demapping unit 48, bit deinterleaving unit 49, depuncture unit 50, Viterbi decoding unit 51, convolutional coding unit 52, puncture unit 53, bit interleaving unit 54, mapping unit 55, time interleaving unit 56 , Frequency interleave unit 57, symbol determination unit 58, remodulation unit 59, delay unit 60, SP / CP Each function of the signal generation unit 61 and the frame reconstruction unit 62 and components from the orthogonal demodulation unit 23 to the frame reconstruction unit 62 included in the interference wave extraction device 1-6 (similar to the interference wave extraction device 1-5) The byte deinterleaving unit 63, the energy despreading unit 64, the Reed-Solomon decoding unit 65, the Reed-Solomon encoding unit 66, the energy spreading unit 67, and the byte interleaving unit 68 also describe these functions. Each is realized by causing the CPU to execute the program. These programs can also be stored and distributed in a storage medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), optical disk (CD-ROM, DVD, etc.), semiconductor memory, or the like.

  The present invention has been described with reference to the first to sixth embodiments. However, the present invention is not limited to the first to sixth embodiments, and various modifications can be made without departing from the technical idea thereof. For example, the quadrature demodulation unit 23 included in the interference wave extraction apparatuses 1-1 to 1-6 according to the first to sixth embodiments performs quadrature demodulation processing using a digital signal, but performs quadrature demodulation processing using an analog signal. You may do it. In addition, the quadrature modulation unit 38 included in the interference wave extraction apparatuses 1-1 to 1-6 according to the first to sixth embodiments performs the quadrature modulation process using the digital signal, but performs the quadrature modulation process using the analog signal. You may do it. In this case, the quadrature demodulator 23 is provided before the A / D converter 22, and the A / D converter 22 includes two A / D converters for the in-phase signal and the quadrature signal. The quadrature modulation unit 38 is provided in the subsequent stage of the D / A conversion unit 39, and the D / A conversion unit 39 is configured by two D / A converters for the in-phase signal and the quadrature signal.

DESCRIPTION OF SYMBOLS 1 Interference wave extraction apparatus 10 Desired wave extraction part 11 Transmission path characteristic calculation part 12 Transmission path characteristic addition part 13 Delay part 14 Desired wave cancellation part 21 BPF
22 A / D conversion unit 23 Orthogonal demodulation unit 24 Synchronous reproduction unit 25 Window processing unit 26, 60 Delay unit 27 FFT unit 28 SP signal extraction unit 29 Transmission path characteristic calculation unit 30 Equalization unit 31 Filter coefficient generation unit 32, 58 Symbol Determination unit 33, 59 Remodulation unit 34 IFFT unit 35 GI addition unit 36 FIR filter unit 37 Subtraction unit 38 Orthogonal modulation unit 39 D / A conversion unit 40 BPF
41 SP signal generating unit 42 SP signal changing unit 43 BPF
44 AFC unit 45 Data symbol separation unit 46 Frequency deinterleaving unit 47 Time deinterleaving unit 48 Demapping unit 49 Bit deinterleaving unit 50 Depuncture unit 51 Viterbi decoding unit 52 Convolutional coding unit 53 Puncture unit 54 Bit interleaving unit 55 Mapping unit 56 Time interleaving unit 57 Frequency interleaving unit 61 SP / CP signal generation unit 62 Frame reconstruction unit 63 Byte deinterleaving unit 64 Energy despreading unit 65 Reed-Solomon decoding unit 66 Reed-Solomon encoding unit 67 Energy spreading unit 68 Byte interleaving unit 441 Phase rotator 442 NCO control data generator 443 NCO
444 Multiplier 445 Subtractor 446 Adder

Claims (12)

An interference wave extraction device that receives a broadcast wave in which a desired wave and an interference wave are mixed and extracts the interference wave from the broadcast wave,
A desired wave extraction unit that equalizes the received broadcast wave signal and extracts the desired wave signal having a reception level higher than the signal of the interference wave from the equalized broadcast wave signal;
A transmission path characteristic calculation unit that calculates a transmission path characteristic using a reference signal included in the received broadcast wave and a preset reference signal;
A transmission line characteristic adding unit that adds the transmission line characteristic calculated by the transmission line characteristic calculation unit to the desired wave signal extracted by the desired wave extraction unit, and generates a desired wave replica signal;
A desired wave cancellation unit that subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the received broadcast wave signal and outputs the signal of the interference wave;
An interference wave extraction device comprising: In the interference wave extraction device according to claim 1,
The desired wave extraction unit extracts a layer A signal from the received broadcast wave OFDM signal by a BPF, demodulates the layer A signal, performs FFT on the demodulated layer A signal, performs equalization processing, and performs symbol processing. The A layer signal of the desired wave is extracted by a hard decision, the A layer signal of the desired wave is output by IFFT,
The transmission line characteristic calculating unit extracts an SP signal from the A layer signal FFTed by the desired wave extracting unit, and calculates the transmission line characteristic by dividing the extracted SP signal by a preset SP signal.
The transmission line characteristic adding unit generates a filter coefficient by performing an IFFT on the transmission line characteristic calculated by the transmission line characteristic calculation unit, and using the filter coefficient by an FIR filter and outputting the filter coefficient A desired wave replica signal is generated from the A layer signal of the desired wave,
The desired wave canceling unit subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the A layer signal demodulated by the desired wave extracting unit to obtain an A layer signal of an interference wave, and A crosstalk wave extracting apparatus for modulating a wave A layer signal. In the interference wave extraction device according to claim 1,
The desired wave extraction unit demodulates the received broadcast wave OFDM signal, performs FFT on the demodulated signal, performs equalization, and extracts the A layer signal of the desired wave by symbol hard decision, IFFT the desired layer A signal and output it.
The transmission line characteristic calculation unit extracts an SP signal from the signal FFTed by the desired wave extraction unit, calculates the transmission line characteristic by dividing the extracted SP signal by a preset SP signal,
The transmission line characteristic adding unit generates a filter coefficient by performing an IFFT on the transmission line characteristic calculated by the transmission line characteristic calculation unit, and using the filter coefficient by an FIR filter and outputting the filter coefficient A desired wave replica signal is generated from the A layer signal of the desired wave,
The desired wave canceling unit subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the signal demodulated by the desired wave extracting unit to obtain an interference wave signal, and obtains the interference wave signal. An interference wave extraction device characterized by modulating. In the interference wave extraction device according to claim 2 or 3,
The desired wave extraction unit adds an SP signal to the A layer signal of the desired wave extracted by the symbol hard decision, and outputs the result by performing IFFT. In the interference wave extraction device according to claim 2,
The desired wave extracting unit extracts a first A layer signal from the received broadcast wave OFDM signal by a BPF that performs analog filter processing, demodulates the first A layer signal, and uses a BPF that performs digital filter processing. A second A layer signal is extracted from the demodulated first A layer signal, the second A layer signal is subjected to FFT, equalization is performed, and the A layer signal of the desired wave is extracted by symbol hard decision Then, an SP signal is added to the A layer signal of the desired wave, IFFT is output,
The desired wave canceling unit subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the second A layer signal extracted by the desired wave extracting unit to obtain an A layer signal of an interference wave An interference wave extraction apparatus characterized by obtaining and modulating the A layer signal of the interference wave. In the interference wave extraction device according to claim 3,
The desired wave extraction unit extracts the first signal of the entire band from the OFDM signal of the received broadcast wave by the BPF that performs analog filter processing, demodulates the first signal, and the BPF that performs digital filter processing The second signal of the entire band is extracted from the demodulated first signal, the second signal is subjected to FFT, equalization is performed, and the A layer signal of the desired wave is extracted by symbol hard decision. SP signal is added to wave A layer signal, IFFT is output,
The desired wave canceling unit subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the second signal extracted by the desired wave extracting unit to obtain an interference wave signal, and An interference wave extraction device for modulating a wave signal. In the interference wave extraction device according to claim 5 or 6,
Furthermore, a synchronous reproduction unit is provided for performing frequency synchronous reproduction processing on the first A layer signal of claim 5 or the first signal of claim 6 demodulated by the desired wave extracting unit to obtain a frequency offset. ,
The desired wave extraction unit removes the frequency offset obtained by the synchronous reproduction unit from the demodulated frequency in the first A-layer signal of claim 5 or the first signal of claim 6, and calculates the frequency offset. An interference wave extracting apparatus, wherein the BPF digital filter processing is performed on the removed signal. In the interference wave extraction device according to claim 2,
Further, the A layer signal demodulated by the desired wave extraction unit includes a synchronous reproduction unit that performs synchronous reproduction processing of the frequency to obtain a frequency offset,
The desired wave extraction unit extracts a first A layer signal from an OFDM signal of the received broadcast wave by a BPF that performs analog filter processing, demodulates the first A layer signal, and demodulates the first A layer signal. The second A layer signal is extracted from the first A layer signal from which the frequency offset obtained by the synchronous reproduction unit is removed from the frequency of the layer signal, and the frequency offset is removed by the BPF that performs digital filter processing. After performing the FFT on the A layer signal of 2, the AC and TMCC signals and the data signal are separated, and frequency deinterleaving, time deinterleaving, demapping, bit deinterleaving, depuncturing are performed on the data signal. And inner code decoding, and for the inner code decoded signal, inner code encoding, puncture, Data signal obtained by performing interleave, mapping, time interleave and frequency interleave processing, obtaining a transmission symbol by symbol hard decision for the AC and TMCC signals, performing remodulation, and performing the frequency interleave processing. The remodulated AC and TMCC signals and predetermined SP and CP signals are combined to generate the desired layer A layer signal, and the desired layer A layer signal is output by IFFT,
The desired wave canceling unit subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the second A layer signal extracted by the desired wave extracting unit to obtain an A layer signal of an interference wave An interference wave extraction apparatus characterized by obtaining and modulating the A layer signal of the interference wave. In the interference wave extraction device according to claim 3,
Further, the signal demodulated by the desired wave extraction unit is provided with a synchronous reproduction unit that performs synchronous reproduction processing of the frequency to obtain a frequency offset,
The desired wave extraction unit extracts a first signal of all bands from the received broadcast wave OFDM signal by a BPF that performs analog filter processing, demodulates the first signal, and demodulates the demodulated first signal. The frequency offset obtained by the synchronous reproduction unit is removed from the frequency, and the second signal of the entire band is extracted from the first signal from which the frequency offset is removed by the BPF that performs digital filter processing, and the second signal is extracted. After FFT, equalization processing is performed to separate AC and TMCC signals and A layer data signals, and frequency deinterleaving, time deinterleaving, demapping, bit deinterleaving, depuncture and inner codes are performed on the data signals. Each decoding process is performed, and the inner code decoded signal is subjected to inner code encoding, puncture, bit interface. A data signal obtained by performing each processing of leave, mapping, time interleaving, and frequency interleaving, obtaining a transmission symbol by symbol hard decision for the AC and TMCC signals, performing remodulation, and performing the frequency interleaving processing, The re-modulated AC and TMCC signals and the predetermined SP and CP signals are combined to generate the desired layer A layer signal, and the desired layer A layer signal is output by IFFT,
The desired wave canceling unit subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the second signal extracted by the desired wave extracting unit to obtain an interference wave signal, and An interference wave extraction device for modulating a wave signal. In the interference wave extraction device according to claim 2,
Further, the A layer signal demodulated by the desired wave extraction unit includes a synchronous reproduction unit that performs synchronous reproduction processing of the frequency to obtain a frequency offset,
The desired wave extraction unit extracts a first A layer signal from an OFDM signal of the received broadcast wave by a BPF that performs analog filter processing, demodulates the first A layer signal, and demodulates the first A layer signal. The second A layer signal is extracted from the first A layer signal from which the frequency offset obtained by the synchronous reproduction unit is removed from the frequency of the layer signal, and the frequency offset is removed by the BPF that performs digital filter processing. After performing the FFT on the A layer signal of 2, the AC and TMCC signals and the data signal are separated, and frequency deinterleaving, time deinterleaving, demapping, bit deinterleaving, depuncturing are performed on the data signal. And inner code decoding, and the inner code decoded signal is subjected to byte deinterleaving and energy Gee despreading, outer code decoding, outer code encoding, energy spreading, and byte interleaving are performed, and for the byte interleaved signal, inner code encoding, puncture, bit interleaving, mapping, time interleaving, and frequency interleaving are performed. Performing each processing, obtaining a transmission symbol by symbol hard decision for the AC and TMCC signals, performing remodulation, and performing the frequency interleaving processing, the remodulated AC and TMCC signals, And a predetermined SP and CP signal are combined to generate the A layer signal of the desired wave, and the A layer signal of the desired wave is output by IFFT,
The desired wave canceling unit subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the second A layer signal extracted by the desired wave extracting unit to obtain an A layer signal of an interference wave An interference wave extraction apparatus characterized by obtaining and modulating the A layer signal of the interference wave. In the interference wave extraction device according to claim 3,
Further, the signal demodulated by the desired wave extraction unit is provided with a synchronous reproduction unit that performs synchronous reproduction processing of the frequency to obtain a frequency offset,
The desired wave extraction unit extracts a first signal of all bands from the received broadcast wave OFDM signal by a BPF that performs analog filter processing, demodulates the first signal, and demodulates the demodulated first signal. The frequency offset obtained by the synchronous reproduction unit is removed from the frequency, and the second signal of the entire band is extracted from the first signal from which the frequency offset is removed by the BPF that performs digital filter processing, and the second signal is extracted. After FFT, equalization processing is performed to separate AC and TMCC signals and A layer data signals, and frequency deinterleaving, time deinterleaving, demapping, bit deinterleaving, depuncture and inner codes are performed on the data signals. Performs each decoding process, byte deinterleave and energy despreading on the inner code decoded signal Performs outer code decoding, outer code encoding, energy spreading, and byte interleaving, and performs inner code encoding, puncture, bit interleaving, mapping, time interleaving, and frequency interleaving on the byte interleaved signal. , A transmission symbol is obtained by symbol hard decision for the AC and TMCC signals, remodulation is performed, the data signal is subjected to the frequency interleaving process, the remodulated AC and TMCC signals, and a predetermined SP. And the CP signal are combined to generate an A layer signal of the desired wave, and the A layer signal of the desired wave is output by IFFT,
The desired wave canceling unit subtracts the desired wave replica signal generated by the transmission path characteristic adding unit from the second signal extracted by the desired wave extracting unit to obtain an interference wave signal, and An interference wave extraction device for modulating a wave signal.   An interference wave extraction program for causing a computer to function as the interference wave extraction device according to any one of claims 1 to 11.

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