201215056 六、發明說明： 【發明所屬之技術領域】 本發明的實施形態係有關於接收正交分頻多工（ OFDM)調變方式之傳輸訊號的OFDM收訊裝置，尤其是有 關於將傅立葉轉換之切出窗位置加以設定的切出窗控制◊ 【先前技術】 近年來，在聲音訊號及映像訊號的傳輸中，盛行數位 調變方式的開發。尤其是，在數位地表波播送中，具有對 於多重路徑干擾抗性強、頻率利用效率高等之特徵的正交 分頻多工（以下稱作OFDM )調變方式，正受到矚目。以 下說明關連於本發明的先前技術。 在日本的地表波數位播送中，是將56 17道副載波進行 OFDM調變而傳輸。在收訊裝置上，以選台器來選台了所 望的OFDM調變訊號之後，以A/D轉換電路來轉換成數位訊 號而藉由數位訊號處理以進行資料解調。此時會利用在頻 率方向及時間方向雜錯配置之分散性導頻訊號（以下稱作 SP訊號）來推定傳輸路徑失真，以等化處理來補正之。 又’ OFDM訊號係由有效符號期間和將有效符號期間 之後端部加以複製而成的保護區間期間所成。在將該時間 領域之訊號進行FFT演算時，要將哪個範圍加以切出而演 算的設定方法，係爲公知技術。若依據此先前技術，則可 根據SP訊號的脈衝響應來評估傳輸路徑特性而決定FFT窗 。甚至’藉由判定干擾波究竟是延遲波還是先行波，就可 -5- 201215056 支援多重路徑干擬達到有效符號長之1/4爲止的延遲時間 〇 如上述，在先前的OFDM收訊裝置中，延遲波的延遲 時間係可支援到有效符號長之1M爲止。然而，隨著錯誤 訂正技術之發展或符號間干擾去除技術之發達，即使在超 過了保護區間期間（以下稱作保護期間）的此種延遲波存 在時，似乎也有能夠收訊之可能性。可是，在先前技術中 ，當有超過有效符號長之1/4之延遲波存在時，係無法控 制FFT窗。甚至，即是在錯誤嘗試性地搜尋FFT窗而進行 控制的情況下，若有超過有效符號長1/3的延遲波存在時 ，則由於對應著收訊符號數而準備的SP符號數之比率是被 限定爲全收訊符號中的1/3，因此在使用SP訊號的脈衝響 應中，無法表現出超過有效符號長1/3之適切波，而無法 求出FFT窗搜尋的基準位置。因此，也無法將FFT窗控制 在收訊品質最佳的位置上。 於是，即使有超過有效符號長1/3的這類延遲波存在 時，仍可將FFT窗控制在收訊品質最佳位置上的OFDM收訊 裝置，是爲人所期望。 【發明內容】 〔發明所欲解決之課題〕 本發明所欲解決之課題係爲提供一種，即使有超過有 效符號長1/3的這類延遲波存在時，仍可將FFT窗控制在收 訊品質最佳位置上的OFDM收訊裝置。201215056 VI. Description of the Invention: [Technical Field] The present invention relates to an OFDM receiving apparatus for receiving a transmission signal of an orthogonal frequency division multiplexing (OFDM) modulation method, and more particularly to transforming Fourier transform Cut-out window control for cutting out the window position ◊ [Prior Art] In recent years, the development of digital modulation methods has been popularized in the transmission of audio signals and video signals. In particular, in the digital surface wave broadcasting, the orthogonal frequency division multiplexing (hereinafter referred to as OFDM) modulation method, which is characterized by strong resistance to multipath interference and high frequency utilization efficiency, is attracting attention. The prior art related to the present invention is explained below. In Japan's surface wave digital broadcasting, 56 17 subcarriers are OFDM modulated and transmitted. On the receiving device, after selecting the desired OFDM modulation signal by the tuner, the A/D conversion circuit converts the digital signal into a digital signal and performs digital signal processing for data demodulation. At this time, the dispersion pilot signal (hereinafter referred to as SP signal) arranged in the frequency direction and the time direction is used to estimate the transmission path distortion, and the equalization processing is used to correct it. Further, the OFDM signal is formed by the period of the effective symbol period and the period of the guard interval in which the end portion of the effective symbol period is copied. When the FFT calculation is performed on the signal of the time domain, the setting method of which range is to be cut out and calculated is a well-known technique. According to this prior art, the FFT window can be determined by evaluating the characteristics of the transmission path based on the impulse response of the SP signal. Even by determining whether the interfering wave is a delayed wave or a preceding wave, it can be -5, 201215056 to support the multipath to achieve a delay time up to 1/4 of the effective symbol length, as described above, in the previous OFDM receiver The delay time of the delayed wave can support up to 1M of the effective symbol length. However, with the development of error correction techniques or the development of inter-symbol interference removal techniques, there seems to be a possibility of being able to receive reception even when such a delayed wave exceeds the guard interval (hereinafter referred to as the protection period). However, in the prior art, when there is a delayed wave exceeding 1/4 of the effective symbol length, the FFT window cannot be controlled. Even in the case where the FFT window is searched for by mistake and the control is performed, if there is a delayed wave exceeding 1/3 of the effective symbol length, the ratio of the number of SP symbols prepared corresponding to the number of received symbols is obtained. It is limited to 1/3 of the full-receipt symbol. Therefore, in the impulse response using the SP signal, a suitable wave exceeding 1/3 of the effective symbol length cannot be expressed, and the reference position of the FFT window search cannot be obtained. Therefore, it is also impossible to control the FFT window at the position where the reception quality is optimal. Therefore, even if such a delayed wave exceeding 1/3 of the effective symbol length exists, it is desirable to control the FFT window to the OFDM receiving apparatus at the optimum position of the reception quality. SUMMARY OF THE INVENTION [Problem to be Solved by the Invention] The problem to be solved by the present invention is to provide an FFT window that can be controlled in reception even if such a delayed wave exceeding 1/3 of the effective symbol length exists. OFDM receiving device at the best quality position.
-6- 201215056 〔用以解決課題之手段〕 實施形態的OFDM收訊裝置，係屬於將含有在頻率方 向及時間方向週期性配置之導頻訊號的OFDM訊號加以收 訊的OFDM收訊裝置，其係具備： 傅立葉轉換手段，係用以將前記OFDM訊號以切出窗 訊號來切出時間領域之訊號然後藉由傅立葉轉換而轉換成 頻率領域之訊號；和 資料解調手段，係用以將該傅立葉轉換手段之輸出予 以解調，獲得解調資料；和 導頻抽出手段，係用以從前記傅立葉轉換手段之輸出 ，抽出前記在頻率方向及時間方向週期性配置之導頻訊號 :和 脈衝響應偵測手段，係用以從前記導頻抽出手段之輸 出，偵測出脈衝響應；和 峰値偵測手段，係用以從前記脈衝響應偵測手段之輸 出，偵測出峰値位置；和 品質偵測手段，係用以偵測出前記OFDM訊號的收訊 品質；和 切出窗控制手段，係用以進行：主波搜尋，係用以使 用來自前記峰値偵測手段之峰値偵測訊號與來自前記品質 偵測手段之品質偵測訊號，以偵測出排除了折返之影響的 真正主波位置；和切出窗精密搜尋，係用以在含有該主波 搜尋所偵測出之主波位置的所定範圍內使傅立葉轉換用切 201215056 出窗位置做步進式變化而進行搜尋，以確定使品質偵測訊 號呈最佳的傅立葉轉換用切出窗位置。 〔發明效果〕 若依據如上記構成的OF DM收訊訊號裝置，則即使有 超過有效符號長1/3的這類延遲波存在時，仍可將FFT窗控 制在收訊品質最佳位置上。 【實施方式】 以下，參照圖面而詳細說明實施形態。 〔第1實施形態〕 圖1係第1實施形態所述之OFDM收訊裝置之構成的區 塊圖。於圖1中，OFDM收訊裝置100係具備有：OFDM調變 訊號的輸入端子101、選台器102、A/D轉換電路103、正交 檢波電路104、屬於傅立葉轉換手段的F FT電路105、屬於 資料解調手段的解調電路106、解調訊號的輸出端子107、 作爲導頻抽出手段的SP抽出電路108、屬於脈衝響應偵測 手段的脈衝響應偵測電路1 09、屬於峰値偵測手段的峰値 偵測電路1 1 0、FFT窗控制電路1 1 1、作爲收訊品質偵測手 段的S/N偵測電路1 12。 OFDM收訊裝置100係爲，將含有在頻率方向及時間方 向週期性配置之導頻訊號亦即SP訊號的OFDM訊號，加以 收訊的OFDM收訊裝置。 201215056 FFT電路105，係將OFDM訊號以切出窗訊號亦即FFT 窗訊號來切出時間領域之訊號然後藉由傅立葉轉換而轉換 成頻率領域之訊號。 SP抽出電路108，係從FFT電路105之輸出，抽出在頻 率方向及時間方向週期性配置之SP訊號。 解調電路106，係將FFT電路105之輸出，基於SP訊號 而進行解調處理，將解調資料輸出至輸出端子107。 脈衝響應偵測電路109，係將SP抽出電路108所抽出的 SP訊號進行傅立葉轉換，以偵測出脈衝響應。 峰値偵測電路1 1 〇，係偵測出從脈衝響應偵測電路1 09 所送來之脈衝響應的峰値位置，作爲峰値偵測訊號（由於 這是並未考慮折返之影響的訊號因此視爲表示暫定主波位 置之訊號）而輸出至FFT窗控制電路1 1 1。 S/N偵測電路1 12，係從來自解調電路106的解調資料 ，偵測出收訊S/N，作爲品質偵測訊號的S/N訊號而輸出至 F F T窗控制電路1 1 1。 FFT窗控制電路1 1 1，係進行：主波搜尋，係用以使用 峰値偵測訊號（表示暫定主波位置之訊號）與S/N訊號而 偵測出排除了折返之影響的真正主波位置；和F F T窗精密 搜尋，係用以在含有該主波搜尋所偵測出之主波位置的所 定範圍內，使FFT窗位置做步進式變化而進行搜尋，以確 定使S/N訊號呈最佳的FFT窗位置。 以下，一面參照圖1 一面說明動作》 對輸入端子101係從未圖示的天線供給著OFDM調變訊 201215056 號，在選台器102中只有所望的OFDM調變訊號會被選台。 選台器102之輸出，係在A/D轉換電路103中被轉換成數位 訊號而供給至正交檢波電路104。A/D轉換電路103之輸出 ’係在正交檢波電路104中進行正交檢波而被轉換成基頻 的同相檢波軸訊號（I訊號）與正交檢波軸訊號（Q訊號） ，然後輸入至FFT電路105。FFT電路105，係在所被輸入 之OFDM調變訊號當中，對於藉由來自FFT窗控制電路111 的FFT窗訊號而被切出之訊號，進行FFT演算。FFT電路 105之輸出係被分歧，其中一方輸出係在解調電路1〇6中基 於SP訊號而進行解調處理，從輸出端子107當作解調資料 輸出而被輸出。 來自FFT電路105的另一方輸出，係被供給至SP抽出電 路108。在SP抽出電路108中，係將如圖5所示，在頻率方 向及時間方向上被交錯配置之SP訊號，予以抽出。在脈衝 響應偵測電路109中，係將已被SP抽出電路108所抽出的頻 率領域之SP訊號予以輸入，實施逆傅立葉轉換演算而偵測 出時間領域的脈衝響應》脈衝響應偵測結果，係被供給至 峰値偵測電路1 1 0，偵測出脈衝響應的峰値位置。所被偵 測出來的峰値位置，係作爲峰値偵測訊號而供給至FFT窗 控制電路11 1。 又’解調電路106之輸出係被供給至S/N偵測電路1 12 ，在S/N偵測電路II2中根據解調資料的訊號分布圖（ constellation )而偵測出收訊S/N然後供給至FFT窗控制電 路 111。 -10- 201215056 FFT窗控制電路111首先進行主波搜尋，一面將FFT窗 在包含暫定主波位置之複數窗基準位置中做切換，一面偵 測S/N訊號以求出排除了折返之影響的真正主波位置。其 後，在所求出的真正主波位置的所定範圍內，一面使F FT 窗做步進式變化，一面進行FFT窗精密搜尋，以偵測出會 使得S/N訊號呈最佳的FFT窗位置，確定FFT窗訊號。 圖2(a)係表示主波及延遲波，圖2(b)係表示使用 了 SP訊號的脈衝響應。此外，延遲波係相對於屬於直接波 的主波，具有延遲時間r。在圖2(a)中，相對於主波而 把延遲波的振幅描繪得較窄的原因，是爲了表示延遲波的 功率是小於主波。1符號係由有效符號期間、和將該有效 符號期間之後端部分予以複製而連接至有效符號期間之前 端而成的保護期間所構成。圖2(b)係將主波及延遲波個 別的有效符號期間之開頭所對應到的脈衝響應之輸出（換 言之係爲延遲側寫輸出），表示在時間軸上的圖。 如圖5所示，OFDM符號的格式係爲，在從送訊側被送 來的狀態下，SP載波係於頻率方向上以每12道載波中有1 道之比率而被插入；此在收訊機側上則是，對於在時間方 向的4道載波中有1道之比率而被插入的SP載波，藉由在時 間方向上進行SP載波之內插，變成SP載波係於頻率方向上 以每3道載波中有1道之比率而被插入。因此，若使用此種 經由內插而以3道中有1道之比率而插入的SP訊號，則一直 到具有相當於有效符號長1/3長度之延遲時間的延遲波， 都可將脈衝響應之輸出予以表現在時間軸上。換言之，1 -11 - 201215056 次脈衝響應只能構表現有效符號長的1/3 (=±1/6)之範圍 〇 圖4係本實施形態所涉及之脈衝響應偵測的說明圖。 當把峰値偵測電路1 1 0所測出之峰値位置（暫定主波 位置）視爲時間軸的基準0的時候，在1次的脈衝響應中在 基準〇之位置上如圖所示般地有1道脈衝響應峰値的情況下 ，可以說其即是主波，但由於作爲脈衝響應之輸出是只能 表現相當於有效符號長1/3長度的時間範圍，因此因此在 時間軸上以0之位置爲中心而遠離± 1 /3之位置上，可能會 如圖示般地存在有延遲訊號或先行訊號。 其結果爲，例如，在時間軸上從基準〇之位置遠離了 有效符號長+1/3之位置的延遲訊號，可能會在+1/6之位置 上折返而被看成〇之位置。或者，從基準〇之位置遠離了有 效符號長-1/3之位置的先行訊號，可能會在-1/6之位置上 折返而被看成〇之位置。如此，在實施形態中，由於曉得 是在±1/6被折返，因此就原理上而言，以將FFT窗設在0之 位置（以〇之位置爲中心的±1/6之範圍）時、設在+1/3之位 置（以+1/3之位置爲中心的±1/6之範圍）時、設在-1/3之 位置（以-1 /3之位置爲中心的± 1 /6之範圍）時的方式而逐 次切換FFT窗位置而嘗試進行FFT，將此時的收訊品質（ 例如收訊S/N )呈最佳時視爲主波的位置，首先找出真正 的主波，其後將包含該主波位置之所定範圍（該範圍係亦 可小於圖示之脈衝響應偵測範圍）的FFT窗位置’ 一面逐 次挪移所定延遲量而改變，一面進行F FT窗位置之精密搜 -12- 201215056 尋，進行偵測（確定）出收訊品質（例如收訊S/N )呈最 佳的FFT窗位置之處理》 圖3係圖示了實施形態所述之FFT窗控制電路1 1 1之構 成。 圖3中，FFT窗控制電路1 1 1係具備有：主波偵測電路 201、窗搜尋電路202、FFT窗設定電路203。 主波偵測電路2 0 1，係使用來自峰値偵測電路1 1 0的峰 値偵測訊號與來自S/N偵測電路1 12的S/N訊號而偵測出真 正主波位置所需的電路。窗搜尋電路202係進行主波搜尋 以偵測出考慮了折返之影響的真正主波位置，另一方面， 基於來自主波偵測電路20 1的主波位置偵測訊號（主波偵 測完了旗標）而在所定之延遲時間範圍內將FFT窗訊號做 精密搜尋，同時選擇出收訊品質最佳的FFT窗訊號。FFT 窗設定電路203，係將從窗搜尋電路202所輸出之表示與主 波位置之偏置的窗偏置訊號、和來自主波偵測電路201的 表示主波位置之窗基準訊號予以合成而生成FFT窗訊號， 供給至FFT電路105。 以下，一面參照圖3 —面說明動作。 對主波偵測電路20 1係供給著，來自峰値偵測電路1 1 0 的峰値偵測訊號與來自S/N偵測電路1 12的S/N訊號。對圖5 所示的送訊時之SP載波配置，藉由在收訊機中所執行的時 間方向之SP載波內插，SP訊號就會在頻率方向上以3載波 間隔而被配置，因此使用了 SP訊號的脈衝響應，係只能表 現到有效符號長的1/3、亦即±1/6爲止的時間。於是，主波 -13- 201215056 偵測電路201係如圖4所示，將FFT窗位置錯開有效符號長 ±1/3時所獲得之S/N訊號與時間長爲0之位置時所獲得之 S/N訊號，進行比較，將S/N訊號最佳之FFT窗位置之時的 峰値，判定爲真正主波。主波偵測電路201係將真正主波 位置供給至FFT窗設定電路203，將主波偵測完了旗標供給 至窗搜尋電路202。窗搜尋電路202，係在主波已被測出後 ，以真正主波位置爲窗基準而在所定範圍內一面使FFT窗 訊號在時間軸上做步進式變化，一面偵測出S/N訊號最佳 的FFT窗訊號而作動。然後，FFT窗設定電路203係將從窗 搜尋電路202所輸出之針對主波位置的窗偏置訊號與來自 主波偵測電路201的窗基準訊號加以合成而生成FFT窗訊號 ，供給至FFT電路105。 圖6係第1實施形態所涉及之動作的說明用流程圖。一 面參照圖6，一面說明FFT窗位置設定動作。 首先，將OFDM訊號中所含之SP訊號予以抽出（步驟 S1 )，基於已被抽出之SP訊號而偵測出脈衝響應（步驟S2 )。脈衝響應係和傳輸路徑響應或是延遲側寫同義。接著 在步驟S 3中，將脈衝響應偵測結果當中的最大峰値，偵測 成爲主波，將其當作主波候補（暫定主波）而進'入步驟S4 的FFT窗基準控制模式（主波搜尋）。 在步驟S4〜S7中，設成步驟S3中所測出的主波位置（ 例如〇 )而在脈衝響應偵測範圍（1 )中設定FFT窗以進行 S/N偵測（步驟S5 )，其後依序執行步驟S6、S7之各步驟 。例如，在主波位置0之後設成主波位置（-1 /3 )而在脈衝 • 14 - 201215056 響應偵測範圍（2 )中設定FFT窗以進行S/Ν偵測，其後設 成主波位置（+1/3)而在脈衝響應偵測範圍（3)中設定 FFT窗以進行S/N偵測（步驟s6、s7 )。若脈衝響應偵測範 圍（1)〜（3)的所有搜尋都結束’則搜尋結果係爲’把 S/Ν最大之FFT窗當作FFT窗基準而前進至下個FFT窗精密 搜尋（步驟S 8 )。 在FFT窗精密搜尋中，首先，以包含有前段的主波搜 尋中所偵測出來的真正主波位置（〇、-1/3、+1/3當中的任 何1者）的方式而將所定範圍（例如脈衝響應偵測範圍（1 )〜（3)之任一範圍均可，但亦可爲更窄的範圍）的FFT 窗朝前後做步進式變化（步驟S9 )，藉此而進行S/Ν偵測 (步驟S10)。然後，針對將該所定範圍（時間幅度）的 FFT窗朝前後做步進式變化的所有精密步驟進行S/Ν偵測（ 步驟S 1 1 )，其後將所有的精密步驟中所偵測出來的S/Ν當 中，把呈最大S/Ν的FFT窗位置，最終加以選擇並確定（步 驟 S12 )。 若依據第1實施形態，則即使有超過有效符號長1 /3的 這類延遲波存在時’仍可將FFT窗控制在收訊品質最佳位 置上。 〔第2實施形態〕 圖7係圖示了第2實施形態所述之0FDM收訊裝置。 於圖7中，OFDM收訊裝置ιοοΑ係具備有：OFDM調變 訊號的輸入端子101、選台器102、A/D轉換電路1〇3、正交 -15- 201215056-6- 201215056 [Means for Solving the Problem] The OFDM receiving apparatus according to the embodiment belongs to an OFDM receiving apparatus that receives an OFDM signal including pilot signals periodically arranged in the frequency direction and the time direction, and The system has: a Fourier transform means for converting the signal of the time domain by cutting out the window signal by the pre-recorded OFDM signal and then converting the signal into the frequency domain by Fourier transform; and the data demodulating means is used for The output of the Fourier transform means is demodulated to obtain demodulated data; and the pilot extraction means is used to extract the pilot signal periodically arranged in the frequency direction and the time direction from the output of the Fourier transform means: and the impulse response The detection means is used for detecting the impulse response from the output of the pre-recorded pilot extraction means; and the peak detection means for detecting the peak position from the output of the pre-recorded impulse response detecting means; The quality detection means is used to detect the reception quality of the pre-recorded OFDM signal; and the cut-out window control means is used for: main wave search, Using the peak detection signal from the pre-recorded peak detection method and the quality detection signal from the pre-record quality detection means to detect the true main wave position excluding the influence of the reentry; and the precise search of the cut-out window, The system performs a step-by-step change in the window position of the Fourier transform to cut the window position in the range containing the main wave position detected by the main wave search to determine the best quality detection signal. The Fourier transform uses the cut-out window position. [Effect of the Invention] According to the OF DM reception signal device constructed as described above, even if such a delayed wave exceeding 1/3 of the effective symbol length exists, the FFT window can be controlled at the optimum position of the reception quality. [Embodiment] Hereinafter, embodiments will be described in detail with reference to the drawings. [First Embodiment] Fig. 1 is a block diagram showing the configuration of an OFDM reception device according to a first embodiment. In FIG. 1, an OFDM receiving apparatus 100 is provided with an input terminal 101 for an OFDM modulation signal, a selector 102, an A/D conversion circuit 103, a quadrature detection circuit 104, and an F FT circuit 105 belonging to a Fourier transform means. The demodulation circuit 106 belonging to the data demodulation means, the output terminal 107 of the demodulation signal, the SP extraction circuit 108 as the pilot extraction means, and the impulse response detection circuit belonging to the impulse response detection means 09, belonging to the peak detection The peak detection circuit 1 1 0 of the measuring means, the FFT window control circuit 1 1 1 , and the S/N detecting circuit 1 12 as the receiving quality detecting means. The OFDM receiving apparatus 100 is an OFDM receiving apparatus that receives an OFDM signal including a SP signal whose pilot signal is periodically arranged in the frequency direction and the time direction. The 201215056 FFT circuit 105 converts the signal of the time domain by cutting out the window signal, that is, the FFT window signal, and then converts the signal into the frequency domain by Fourier transform. The SP extraction circuit 108 extracts the SP signals periodically arranged in the frequency direction and the time direction from the output of the FFT circuit 105. The demodulation circuit 106 performs demodulation processing on the output of the FFT circuit 105 based on the SP signal, and outputs the demodulated data to the output terminal 107. The impulse response detecting circuit 109 performs Fourier transform on the SP signal extracted by the SP extraction circuit 108 to detect the impulse response. The peak detection circuit 1 1 侦测 detects the peak position of the impulse response sent from the impulse response detection circuit 109 as a peak detection signal (since this is a signal that does not consider the effect of the foldback) Therefore, it is regarded as a signal indicating the tentative main wave position) and is output to the FFT window control circuit 1 1 1 . The S/N detecting circuit 1 12 detects the receiving S/N from the demodulated data from the demodulating circuit 106, and outputs it to the FFT window control circuit 1 1 1 as the S/N signal of the quality detecting signal. . The FFT window control circuit 1 1 1 performs: main wave search, which is used to detect the true master that excludes the influence of the reentry by using the peak detection signal (signal indicating the tentative main wave position) and the S/N signal. Wave position; and FFT window precision search is used to make a stepwise change of the FFT window position within a predetermined range containing the main wave position detected by the main wave search to determine S/N The signal is in the best FFT window position. Hereinafter, the operation of the OFDM modulation signal 201215056 is applied to the input terminal 101 from an antenna (not shown), and only the desired OFDM modulation signal is selected in the channel selector 102. The output of the selector 102 is converted into a digital signal by the A/D conversion circuit 103 and supplied to the quadrature detecting circuit 104. The output of the A/D conversion circuit 103 is subjected to quadrature detection in the quadrature detection circuit 104, and is converted into an in-phase detection axis signal (I signal) of the fundamental frequency and a quadrature detection axis signal (Q signal), and then input to FFT circuit 105. The FFT circuit 105 performs FFT calculation on the signal which is cut out by the FFT window signal from the FFT window control circuit 111 among the input OFDM modulation signals. The output of the FFT circuit 105 is divided, and one of the outputs is demodulated based on the SP signal in the demodulation circuit 1〇6, and is output as the demodulated data output from the output terminal 107. The other output from the FFT circuit 105 is supplied to the SP extraction circuit 108. In the SP extraction circuit 108, the SP signals which are alternately arranged in the frequency direction and the time direction are extracted as shown in Fig. 5 . In the impulse response detecting circuit 109, the SP signal of the frequency domain extracted by the SP extraction circuit 108 is input, and the inverse Fourier transform calculation is performed to detect the impulse response of the time domain" impulse response detection result. It is supplied to the peak detection circuit 1 1 0 to detect the peak position of the impulse response. The detected peak position is supplied to the FFT window control circuit 11 1 as a peak detection signal. Further, the output of the 'demodulation circuit 106 is supplied to the S/N detection circuit 1 12, and the S/N detection circuit II2 detects the reception S/N according to the signal distribution of the demodulated data. It is then supplied to the FFT window control circuit 111. -10- 201215056 The FFT window control circuit 111 first performs the main wave search, and switches the FFT window in the reference position of the complex window including the tentative main wave position, and detects the S/N signal to find out the influence of the reentry. The true main wave position. Then, within the predetermined range of the obtained true main wave position, the F FT window is stepwisely changed, and the FFT window is precisely searched to detect the FFT which makes the S/N signal optimal. The window position determines the FFT window signal. Fig. 2(a) shows the main wave and the delayed wave, and Fig. 2(b) shows the impulse response using the SP signal. Further, the delayed wave system has a delay time r with respect to the main wave belonging to the direct wave. In Fig. 2(a), the reason why the amplitude of the delayed wave is drawn narrowly with respect to the main wave is to indicate that the power of the delayed wave is smaller than the main wave. The 1 symbol is composed of a valid symbol period and a guard period in which the rear end portion of the valid symbol period is copied and connected to the front end of the effective symbol period. Fig. 2(b) shows the output of the impulse response corresponding to the beginning of the effective symbol period of the main wave and the delayed wave (in other words, the delayed side write output), and shows the graph on the time axis. As shown in FIG. 5, the format of the OFDM symbol is such that, in a state sent from the transmitting side, the SP carrier is inserted in the frequency direction at a ratio of one channel per 12 carriers; On the signal side, the SP carrier inserted for the ratio of one channel of the four carriers in the time direction is interpolated by the SP carrier in the time direction, so that the SP carrier is in the frequency direction. A ratio of one channel is inserted for every three carriers. Therefore, if such an SP signal inserted by a ratio of one channel of three channels by interpolation is used, the delayed response wave having a delay time equivalent to 1/3 of the length of the effective symbol can be used for the impulse response. The output is represented on the timeline. In other words, the 1 -11 - 201215056 impulse response can only represent a range of 1/3 (= ± 1/6) of the effective symbol length. 〇 FIG. 4 is an explanatory diagram of the impulse response detection according to the present embodiment. When the peak position (tentative main wave position) measured by the peak detection circuit 1 10 is regarded as the reference 0 of the time axis, the position of the reference 〇 in the impulse response of one time is as shown in the figure. In the case where there is one impulse response peak, it can be said that it is the main wave, but since the output as the impulse response can only represent a time range equivalent to 1/3 of the length of the effective symbol, therefore, in the time axis At a position away from ±1 /3 centered on the position of 0, there may be a delay signal or an advance signal as shown. As a result, for example, a delay signal on the time axis that is away from the position of the reference pupil by +1/3 of the effective symbol length may be folded back at the position of +1/6 to be regarded as the position of the 〇. Alternatively, the leading signal from the position of the reference mark away from the position of -1/3 of the effective symbol may be folded back at the -1/6 position and regarded as the position of the 。. Thus, in the embodiment, since it is known that it is folded back by ±1/6, in principle, when the FFT window is set to the position of 0 (the range of ±1/6 centered on the position of the 〇) When the position is +1/3 (the range of ±1/6 centered at the position of +1/3), it is set at -1/3 (± 1 centered at the position of -1/3) Try to perform FFT by switching the FFT window position one by one in the range of /6, and consider the position of the main wave when the reception quality (such as receiving S/N) at this time is optimal. First, find out the real The main wave is then changed to include the range of the main wave position (the range is also smaller than the illustrated impulse response detection range). The FFT window position is changed by shifting the delay amount one by one, and the F FT window position is performed.精密精密-12-201215056 寻, to detect (determine) the reception quality (such as receiving S / N) is the best FFT window position processing" Figure 3 shows the FFT window described in the embodiment The configuration of the control circuit 1 1 1. In Fig. 3, the FFT window control circuit 11 1 includes a main wave detecting circuit 201, a window search circuit 202, and an FFT window setting circuit 203. The main wave detecting circuit 2 0 1 detects the true main wave position by using the peak detecting signal from the peak detecting circuit 1 1 0 and the S/N signal from the S/N detecting circuit 12 12 . Required circuit. The window search circuit 202 performs a main wave search to detect a true main wave position in consideration of the influence of the reentry, and on the other hand, based on the main wave position detecting signal from the main wave detecting circuit 20 1 (the main wave is detected) The flag is used to perform a precise search of the FFT window signal within a predetermined delay time range, and at the same time select the FFT window signal with the best reception quality. The FFT window setting circuit 203 synthesizes the window offset signal indicating the offset from the main wave position output from the window search circuit 202 and the window reference signal indicating the main wave position from the main wave detecting circuit 201. The FFT window signal is generated and supplied to the FFT circuit 105. Hereinafter, the operation will be described with reference to Fig. 3 . The main wave detecting circuit 20 1 supplies the peak detecting signal from the peak detecting circuit 1 10 and the S/N signal from the S/N detecting circuit 12 12 . For the SP carrier configuration at the time of transmission shown in FIG. 5, the SP signal is interpolated in the frequency direction by the SP carrier interpolation performed in the receiver, so that the SP signal is configured at a carrier interval of 3 carriers. The impulse response of the SP signal can only be expressed as 1/3 of the effective symbol length, that is, ±1/6. Therefore, the main wave-13-201215056 detecting circuit 201 is obtained as shown in FIG. 4, and the FFT window position is shifted by the effective symbol length ± 1/3 when the S/N signal and the time length are 0. The S/N signal is compared and the peak value at the time of the FFT window position with the best S/N signal is determined as the true main wave. The main wave detecting circuit 201 supplies the true main wave position to the FFT window setting circuit 203, and supplies the main wave detected flag to the window search circuit 202. The window search circuit 202 detects the S/N when the main wave has been measured and the FFT window signal is stepwise changed on the time axis within the predetermined range with the true main wave position as the window reference. The signal with the best FFT window signal is activated. Then, the FFT window setting circuit 203 synthesizes the window bias signal for the main wave position output from the window search circuit 202 and the window reference signal from the main wave detecting circuit 201 to generate an FFT window signal, which is supplied to the FFT circuit. 105. Fig. 6 is a flow chart for explaining the operation of the first embodiment. The FFT window position setting operation will be described with reference to Fig. 6 on one side. First, the SP signal contained in the OFDM signal is extracted (step S1), and an impulse response is detected based on the SP signal that has been extracted (step S2). The impulse response system is synonymous with the transmission path response or the delayed side write. Next, in step S3, the maximum peak 当中 of the impulse response detection result is detected as the main wave, and is regarded as the main wave candidate (tentative main wave) and proceeds to the FFT window reference control mode of step S4 ( Main wave search). In steps S4 to S7, the main wave position (for example, 〇) measured in step S3 is set, and the FFT window is set in the impulse response detection range (1) to perform S/N detection (step S5). Then, the steps of steps S6 and S7 are sequentially performed. For example, set the main wave position (-1 /3) after the main wave position 0 and set the FFT window for S/Ν detection in the pulse • 14 - 201215056 response detection range (2), and then set it as the main The wave position (+1/3) is set in the impulse response detection range (3) to perform S/N detection (steps s6, s7). If all the searches for the impulse response detection range (1) to (3) are completed, the search result is 'the S/Ν maximum FFT window is used as the FFT window reference and proceeds to the next FFT window for precise search (step S 8 ). In the FFT window precision search, first, the true main wave position (any one of 〇, -1/3, +1/3) detected in the main wave search including the previous stage is determined. The FFT window of a range (for example, any range of the impulse response detection ranges (1) to (3), but may be a narrower range) is stepwise changed back and forth (step S9), thereby performing S/Ν detection (step S10). Then, S/Ν detection is performed for all the precise steps of stepping the FFT window of the predetermined range (time width) toward the front and the back (step S 1 1 ), and then detected in all the precision steps. Among the S/Ν, the FFT window position which is the maximum S/Ν is finally selected and determined (step S12). According to the first embodiment, even if such a delayed wave exceeding the effective symbol length of 1/3 exists, the FFT window can be controlled at the optimum position of the reception quality. [Second Embodiment] Fig. 7 is a diagram showing an OFDM receiving apparatus according to a second embodiment. In FIG. 7, the OFDM receiving apparatus is provided with an input terminal 101 for an OFDM modulation signal, a selector 102, an A/D conversion circuit 1〇3, and an orthogonal -15-201215056.
檢波電路104、FFT電路105、解調電路106、解調訊號的輸 出端子107、SP抽出電路108、脈衝響應偵測電路109A、峰 値偵測電路1 10、FFT窗控制電路1 1 1、S/N偵測電路1 12A 與第1實施形態的構成上之差異點，係爲脈衝響應偵 測電路109人及3/1^偵測電路112八。在第1實施形態中是基 於解調電路106之輸出而進行S/N偵測之構成，但在本第2 實施形態中則是基於脈衝響應偵測電路1 09A之輸出而進行 S/N偵測之構成。此外，和圖1相同之構成要素係標示同一 符號並省略說明。 脈衝響應偵測電路1 09A，係將脈衝輕應偵測結果供給 至峰値偵測電路1 1 0，鸿且也供給之S/N偵測電路1 1 2A。在 S/N偵測電路112A中，根據脈衝響應偵測電路109A之輸出 而計算出所定臨界値以下之位準的訊號之功率。由於當 S/N較差時該値會較大，因此例如可求出該値的倒數來當 作S/N訊號而使用。 若依據第2實施形態，則在S/N訊號偵測時，由於不使 用解調資料因此在進行解調前可控制FFT窗，具有響應性 佳的優點。 〔第3實施形態〕 圖8係第3實施形態所述之OFDM收訊裝置的區塊圖。 於圖8中，OFDM收訊裝置100B係具備有：OFDM調變 訊號的輸入端子101、選台器102、A/D轉換電路103、正交 -16- 201215056 檢波電路104、FFT電路105A、解調電路106A、解調訊號 的輸出端子107、FFT電路105、解調電路106、SP抽出電路 108、脈衝響應偵測電路109、峰値偵測電路1 10、FFT窗控 制電路1 1 1、S/N偵測電路1 12。 在第1及第2實施形態中，雖然說明了主線系之一部分 的FFT電路及解調電路是被共用來進行FFT窗控制之構成 ，但亦可構成爲，FFT電路後段都具備2份，平行於主線系 之資料解調而進行FFT窗控制處理。 與第1及第2實施形態的構成上之差異點，係爲另外設 置了主線系的FFT電路105A及解調電路106A之構成。FFT 電路105A及解調電路106A係亦可各自是與FFT窗控制之處 理系之中的FFT電路105及解調電路106完全相同的電路。 圖9係第3實施形態所涉及之動作的說明用流程圖。 與圖6所示的第2實施形態的流程圖的不同點在於，將 步驟S12所確定之FFT窗位置，回送至步驟S1而重複連續進 行FFT窗搜尋而動作，還有將步驟S12所確定之FFT窗訊號 ，輸出至主線系的FFT電路105 A這點。其他步驟係和圖6 相同，因此省略說明》 若依據第3實施形態，則藉由與主線系之資料解調並 列地設置FFT窗控制之處理系，使其平行地進行處理，可 使FFT窗搜尋連續重複動作，因此當傳輸路徑的狀況有變 化時，可以追隨之。 如以上所述，若依據本發明，則即使有超過有效符號 長1/3的這類延遲波存在時，仍可將FFT窗控制成使得收訊 -17- 201215056 品質呈現最佳。 此外，雖然說明了本發明的數個實施形態，但這些實 施形態係只是作爲提示的例子，並非意在限定發明的範圍 。這些新穎的實施形態，係可用其他各種形態來實施，在 不脫離發明要旨的範圍內，可進行各種省略、置換、變更 。這些實施形態或其變形，係被包含在發明之範圍或要旨 ，並且被包含在申請專利範圍中所記載之發明和其均等範 圍中。 【圖式簡單說明】 〔圖1〕第1實施形態之OFDM收訊裝置的區塊圖。 〔圖2〕主波及延遲波，與使用SP訊號之脈衝響應的 圖示。 〔圖3〕實施形態中的FFT窗控制電路的區塊圖。 〔圖4〕實施形態所涉及之脈衝響應偵測的說明圖。 〔圖5〕實施形態所涉及之OFDM方式中的SP載波之配 置的說明圖》 〔圖6〕第1實施形態所涉及之動作的說明用流程圖。 〔圖7〕第2實施形態之OFDM收訊裝置的區塊圖。 〔圖8〕第3實施形態之OFDM收訊裝置的區塊圖。 〔圖9〕第3實施形態所涉及之動作的說明用流程圖。 【主要元件符號說明】 100 : OFDM收訊裝置 -18- 201215056 1 Ο 1 :輸入端子 102 :選台器 103 : A/D轉換電路 104 :正交檢波電路 105 ： FFT電路 1 0 6 :解調電路 1 〇 7 :輸出端子 108 : SP抽出電路 109 :脈衝響應偵測電路 1 1 0 :峰値偵測電路 1 1 1 : FFT窗控制電路 1 12 : S/N偵測電路 201 :主波偵測電路 202 :窗搜尋電路 203 : FFT窗設定電路 1 00Α : OFDM收訊裝置 100B : OFDM收訊裝置 105A : FFT電路 1 0 6 A :解調電路 109A :脈衝響應偵測電路 1 12A : S/N偵測電路Detection circuit 104, FFT circuit 105, demodulation circuit 106, output terminal 107 of demodulation signal, SP extraction circuit 108, impulse response detection circuit 109A, peak detection circuit 10, FFT window control circuit 1 1 1 , S The difference between the configuration of the /N detecting circuit 1 12A and the first embodiment is the impulse response detecting circuit 109 and the 3/1 detecting circuit 112. In the first embodiment, the S/N detection is performed based on the output of the demodulation circuit 106. However, in the second embodiment, the S/N detection is performed based on the output of the impulse response detecting circuit 109A. The composition of the test. The same components as those in Fig. 1 are denoted by the same reference numerals and will not be described. The impulse response detecting circuit 1 09A supplies the pulse light detection result to the peak detection circuit 1 1 0, and also supplies the S/N detection circuit 1 1 2A. In the S/N detecting circuit 112A, the power of the signal of the level below the predetermined threshold is calculated based on the output of the impulse response detecting circuit 109A. Since the 値 is large when the S/N is poor, for example, the reciprocal of the 値 can be obtained and used as an S/N signal. According to the second embodiment, in the case of S/N signal detection, since the demodulated data is not used, the FFT window can be controlled before demodulation, and the responsiveness is excellent. [Third Embodiment] Fig. 8 is a block diagram of an OFDM reception device according to a third embodiment. In FIG. 8, the OFDM receiving apparatus 100B includes an input terminal 101 for an OFDM modulation signal, a selector 102, an A/D conversion circuit 103, an orthogonal-16-201215056 detection circuit 104, an FFT circuit 105A, and a solution. The adjustment circuit 106A, the output terminal 107 of the demodulation signal, the FFT circuit 105, the demodulation circuit 106, the SP extraction circuit 108, the impulse response detection circuit 109, the peak detection circuit 1 10, the FFT window control circuit 1 1 1 , S /N detection circuit 1 12. In the first and second embodiments, the FFT circuit and the demodulation circuit of one part of the main line system are collectively used for FFT window control. However, the FFT circuit may be configured to have two copies in parallel. The FFT window control process is performed by demodulating the data of the main line system. The difference from the configuration of the first and second embodiments is that the FFT circuit 105A and the demodulation circuit 106A of the main line system are separately provided. The FFT circuit 105A and the demodulation circuit 106A may each be completely identical to the FFT circuit 105 and the demodulation circuit 106 among the FFT window control systems. Fig. 9 is a flow chart for explaining the operation of the third embodiment. The difference from the flowchart of the second embodiment shown in FIG. 6 is that the FFT window position determined in step S12 is sent back to step S1 to repeat the continuous FFT window search operation, and the step S12 is determined. The FFT window signal is output to the FFT circuit 105 A of the main line system. The other steps are the same as those in Fig. 6, and therefore the description is omitted. According to the third embodiment, the processing system of the FFT window control is arranged in parallel with the data demodulation of the main line system, and the processing is performed in parallel to enable the FFT window. Search for continuous repetitive actions, so when the status of the transmission path changes, you can follow. As described above, according to the present invention, even if such a delayed wave exceeding 1/3 of the effective symbol length exists, the FFT window can be controlled so that the reception -17-201215056 quality is optimal. In addition, although the embodiments of the present invention have been described, these embodiments are merely illustrative and are not intended to limit the scope of the invention. The present invention may be embodied in a variety of other forms, and various omissions, substitutions and changes may be made without departing from the scope of the invention. The invention or its modifications are intended to be included within the scope of the invention and the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] A block diagram of an OFDM receiving apparatus according to a first embodiment. [Fig. 2] A diagram of the main wave and the delayed wave, and the impulse response using the SP signal. Fig. 3 is a block diagram of an FFT window control circuit in the embodiment. Fig. 4 is an explanatory diagram of impulse response detection according to an embodiment. [Fig. 5] Fig. 5 is an explanatory diagram for explaining the arrangement of the SP carrier in the OFDM system according to the embodiment. Fig. 6 is a flowchart for explaining the operation of the first embodiment. Fig. 7 is a block diagram of an OFDM receiving apparatus according to a second embodiment. Fig. 8 is a block diagram of an OFDM receiving apparatus according to a third embodiment. Fig. 9 is a flow chart for explaining the operation of the third embodiment. [Description of main component symbols] 100 : OFDM receiver -18- 201215056 1 Ο 1 : Input terminal 102 : Selector 103 : A/D converter circuit 104 : Quadrature detector circuit 105 : FFT circuit 1 0 6 : Demodulation Circuit 1 〇 7 : Output terminal 108 : SP extraction circuit 109 : impulse response detection circuit 1 1 0 : peak detection circuit 1 1 1 : FFT window control circuit 1 12 : S/N detection circuit 201 : main wave detection Measuring circuit 202: window search circuit 203: FFT window setting circuit 100 Α: OFDM receiving device 100B: OFDM receiving device 105A: FFT circuit 1 0 6 A: demodulating circuit 109A: impulse response detecting circuit 1 12A : S/ N detection circuit