JP2008109359A

JP2008109359A - Ofdm receiver

Info

Publication number: JP2008109359A
Application number: JP2006289821A
Authority: JP
Inventors: Sachiro Kajima; 幸朗鹿嶋; Katsuhiro Hamada; 勝浩浜田; Akitomo Satake; 顕知佐竹
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2006-10-25
Filing date: 2006-10-25
Publication date: 2008-05-08

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that it is necessary to provide not simple circuit configurations but complicate circuit configurations in order to confirm the existence of an SFN wave by a receiver in a reception environment where the SFN wave exists, and it is necessary to spend huge manufacturing costs for its achievement. <P>SOLUTION: This OFDM receiver is provided with a means for detecting the guard correlation of a main broadcast wave and a plurality of SFN to be transmitted by the same frequency, and for properly controlling FFT window position on the basis of the detected guard correlation, and for digitizing and outputting the FFT window position information acquired by those control and a means for calculating and displaying the output FFT window position information. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明はＢＳ、地上波等の放送を受信するＴＶ、ＳＴＢ（セット・トップ・ボックス）、ハードディスクおよびＤＶＤレコーダーなどのＯＦＤＭ受信装置（国際特許分類Ｈ０４Ｂ１／１６，１／１８）に関するものである。 The present invention relates to an OFDM receiver (International Patent Classification H04B 1/16, 1/18) such as a TV, a STB (Set Top Box), a hard disk, and a DVD recorder that receive broadcasts such as BS and terrestrial waves. .

近年、放送のデジタル化が世界的に進展し、欧州ではＯＦＤＭを用いたＤＶＢ−Ｔ方式対応受信機がＴＶの薄型化を伴い急速に普及しており、国内においても欧州と同じく、ＯＦＤＭを用いたＩＳＤＢ−Ｔ方式の地上波デジタル放送が２００３年に開始され、２００６年には全世帯の８０％以上をカバーする予定となっており、ＯＦＤＭの大きな特徴である同一周波数による中継局構成、所謂ＳＦＮ（ＳｉｎｇｌｅＦｒｅｑｕｅｎｃｙＮｅｔｗｏｒｋ）の運用により周波数の有効利用を図るべく中継局の拡充が進められているのが現状である。 In recent years, digitalization of broadcasting has progressed globally. In Europe, DVB-T receivers that use OFDM have rapidly become widespread with the thinning of TVs. The ISDB-T digital terrestrial broadcasting started in 2003 and is scheduled to cover more than 80% of all households in 2006. The structure of relay stations using the same frequency, which is a major feature of OFDM, the so-called At present, the expansion of relay stations is being promoted in order to make effective use of frequencies through the operation of SFN (Single Frequency Network).

従来、異なる複数の中継所から同一周波数にて送信されるＳＦＮ波の存在を確認するには図３に示す特許文献１のように、予め決められたキャリア位置に振幅・位相等化用のパイロット信号が配置されたデジタルベースバンドのＯＦＤＭ信号をＦＦＴ処理するＦＦＴ手段と、この手段のＦＦＴ出力から前記パイロット信号を抽出するパイロット信号抽出手段と、この手段で抽出されたパイロット信号から入力信号の振幅周波数特性及び位相周波数特性を推定する特定推定手段と、この手段で推定された特性値をＩＦＦＴ処理し、振幅値及び位相値を検出するＩＦＦＴ手段を具備することが必要であった。 Conventionally, in order to confirm the existence of SFN waves transmitted from a plurality of different relay stations at the same frequency, a pilot for amplitude / phase equalization at a predetermined carrier position as shown in Patent Document 1 shown in FIG. FFT means for FFT processing of a digital baseband OFDM signal in which the signal is arranged, pilot signal extraction means for extracting the pilot signal from the FFT output of this means, and amplitude of the input signal from the pilot signal extracted by this means It is necessary to include specific estimation means for estimating frequency characteristics and phase frequency characteristics, and IFFT means for performing IFFT processing on the characteristic values estimated by the means and detecting amplitude values and phase values.

しかしながら、これらの方式は業務用測定器を前提とした複雑な回路構成のため、ＴＶやＳＴＢ等の民生用機器で実現するには大きなコストアップが必要であった。
特開２０００−１１５０８７号公報 However, since these systems have a complicated circuit configuration on the premise of a commercial measuring instrument, a large increase in cost is required to be realized with a consumer device such as a TV or STB.
JP 2000-115087 A

解決しようとする問題点は、ＳＦＮの存在を確認するためには、複雑な回路構成とその実現に大きな製造コストを要する点である。 The problem to be solved is that in order to confirm the presence of SFN, a complicated circuit configuration and a large manufacturing cost are required for its realization.

本発明は上記の問題を解決し、特別な回路の追加を必要とすることなくＳＦＮ波の存在を確認可能なＯＦＤＭ受信装置を安価に提供することを特徴とする。 The present invention solves the above problems and provides an inexpensive OFDM receiver capable of confirming the presence of an SFN wave without requiring the addition of a special circuit.

本発明のＯＦＤＭ受信装置は、ＩＦＦＴ等の特別な回路を必要とせず簡単な構成でＳＦＮ波の存在を確認できるため、受信障害発生時にＯＦＤＭ受信装置の故障かＳＦＮ波によるアンテナ調整を含む受信システムの問題かを容易に切り分けることができる安価なＯＦＤＭ受信装置を提供できるという利点がある。 The OFDM receiver of the present invention does not require a special circuit such as IFFT and can confirm the presence of an SFN wave with a simple configuration. Therefore, when a reception failure occurs, the OFDM reception apparatus includes a failure of the OFDM receiver or an antenna adjustment by an SFN wave. There is an advantage that it is possible to provide an inexpensive OFDM receiver capable of easily classifying the above problems.

ＳＦＮが運用されている受信環境において、ＳＦＮ波と主たる放送波とのガード相関を用いたＦＦＴ窓位置情報に簡単な演算を行い、表示することによってＳＦＮの存在を確認する目的を、特別な回路を必要としない簡易な方法で実現した。 In a reception environment where the SFN is operated, a special circuit is used for the purpose of confirming the presence of the SFN by performing simple calculation and displaying the FFT window position information using the guard correlation between the SFN wave and the main broadcast wave. Realized in a simple way that does not require.

（実施の形態１）
図１は本発明のＯＦＤＭ受信装置の１実施例を示すブロック図である。図１において、１は選局回路、２はＡＤコンバータ、３はＡＦＣ回路、４は同期回路、５はＦＦＴ回路、６は誤り訂正回路、７はシステムＬＳＩ、８は演算回路、９は表示回路である。 (Embodiment 1)
FIG. 1 is a block diagram showing an embodiment of an OFDM receiver of the present invention. In FIG. 1, 1 is a channel selection circuit, 2 is an AD converter, 3 is an AFC circuit, 4 is a synchronization circuit, 5 is an FFT circuit, 6 is an error correction circuit, 7 is a system LSI, 8 is an arithmetic circuit, and 9 is a display circuit. It is.

図２は本発明のＯＦＤＭ受信装置の画像表示を示す概略図である。図２において、
１０はＯＦＤＭ受信装置本体、１１は表示画面、１２〜１４はＦＦＴ窓位置インジケータであり、１２はＳＦＮ波の遅延がガードインターバル（以下Ｔｇと略す）よりも十分小さい場合のＦＦＴ窓位置インジケータ表示、１３はＳＦＮ波の遅延が−Ｔｇよりも小さい場合のＦＦＴ窓位置インジケータ表示、１４はＳＦＮ波の遅延が＋Ｔｇよりも大きい場合のＦＦＴ窓位置インジケータ表示である。 FIG. 2 is a schematic diagram showing an image display of the OFDM receiver of the present invention. In FIG.
10 is an OFDM receiver main body, 11 is a display screen, 12 to 14 are FFT window position indicators, and 12 is an FFT window position indicator display when the SFN wave delay is sufficiently smaller than a guard interval (hereinafter abbreviated as Tg). 13 is an FFT window position indicator display when the SFN wave delay is smaller than -Tg, and 14 is an FFT window position indicator display when the SFN wave delay is larger than + Tg.

以上のように構成される受信装置の動作について、以下、説明する。 The operation of the receiving apparatus configured as described above will be described below.

ＵＨＦなどの高周波信号で送信されるＳＦＮ波を含む放送波は、選局回路１で周波数変換されＡＤコンバータ２によってデジタル信号に変換される。デジタル信号に変換されたＳＦＮ波を含む放送波はＡＦＣ回路３で周波数変動を抑制され、同期回路４によってＯＦＤＭシンボルに同期すると共に、主たる放送波とＳＦＮ波とのガード相関より、最良の受信品質が得られるようにＦＦＴ窓位置を決定する。ここでは、一例としてＳＦＮ波が主たる放送波より早く到達する場合とＳＦＮ波が主たる放送波よりも遅く到達する場合の全てのケースで、８段階（０〜７）のＦＦＴ窓位置設定が可能として説明する。 A broadcast wave including an SFN wave transmitted as a high-frequency signal such as UHF is frequency-converted by the channel selection circuit 1 and converted into a digital signal by the AD converter 2. The broadcast wave including the SFN wave converted into the digital signal is suppressed in frequency fluctuation by the AFC circuit 3 and is synchronized with the OFDM symbol by the synchronization circuit 4, and the best reception quality is obtained from the guard correlation between the main broadcast wave and the SFN wave. The FFT window position is determined so that. Here, as an example, in all cases where the SFN wave arrives earlier than the main broadcast wave and the SFN wave arrives later than the main broadcast wave, the FFT window position can be set in eight steps (0 to 7). explain.

まず、ＳＦＮ波の主たる放送波に対する遅延が、Ｔｇ（ここでは１例として１２６μｓｅｃとする）よりも十分に小さい場合には、（例えば±５０μｓｅｃ）ＦＦＴ窓位置は０〜７の全ての段階で受信性能を確保できるため、一定の値を取らず常時変化しているが、ＳＦＮ波が主たる放送波に対してＴｇと同等の遅延量（−１２６μｓｅｃ）で到達する場合にはＦＦＴ窓位置は０が受信性能最適となり、同じく遅延量が＋１２６μｓｅｃの場合にはＦＦＴ窓位置として７が受信性能最適として選択される。 First, if the delay of the SFN wave with respect to the main broadcast wave is sufficiently smaller than Tg (in this example, 126 μsec) (for example, ± 50 μsec), the FFT window position is received at all stages 0 to 7. Since the performance can be secured, it does not take a constant value and is constantly changing. However, when the SFN wave reaches the main broadcast wave with a delay amount equivalent to Tg (−126 μsec), the FFT window position is 0. The reception performance is optimized. Similarly, when the delay amount is +126 μsec, 7 is selected as the optimum reception performance as the FFT window position.

そこで、本実施例ではＳＦＮ波の主たる放送波に対する遅延がＴｇと比較し十分小さい場合にはＦＦＴ窓位置の読み値を平均する等の簡単な演算を行い、図２のＦＦＴ窓位置インジケータ表示１２に示すようにＦＦＴ窓位置インジケータの表示位置及び表示色を決定する。同様にＳＦＮ波の主たる放送波に対する遅延が−Ｔｇよりも小さい場合にはＦＦＴ窓位置を０とする場合が最適となるためＦＦＴ窓位置インジケータ表示１３に示すようにＦＦＴ窓位置インジケータの表示位置及び表示色を決定する。同じくＳＦＮ波の主たる放送波に対する遅延が＋Ｔｇよりも大きい場合にはＦＦＴ窓位置を７とする場合が最適となるためＦＦＴ窓位置インジケータ表示１４に示すようにインジケータの表示位置及び表示色を決定する。ここで、ＦＦＴ窓位置インジケータ１３及びＦＦＴ窓位置インジケータ１４の表示色は、ＳＦＮ波の遅延量が−Ｔｇ以下または＋Ｔｇ以上の場合、受信性能劣化の可能性を促すため、ＳＦＮ波の遅延量が±Ｔｇ以内に十分収まっている場合と異なる表示色としている。 Therefore, in this embodiment, when the delay of the SFN wave with respect to the main broadcast wave is sufficiently small compared to Tg, a simple calculation such as averaging the reading values of the FFT window position is performed, and the FFT window position indicator display 12 in FIG. The display position and display color of the FFT window position indicator are determined as shown in FIG. Similarly, when the delay of the SFN wave with respect to the main broadcast wave is smaller than -Tg, it is optimal to set the FFT window position to 0. Therefore, as shown in the FFT window position indicator display 13, the display position of the FFT window position indicator and Determine the display color. Similarly, when the delay of the SFN wave with respect to the main broadcast wave is larger than + Tg, it is optimal to set the FFT window position to 7, so the display position and display color of the indicator are determined as shown in the FFT window position indicator display 14. . Here, the display colors of the FFT window position indicator 13 and the FFT window position indicator 14 indicate that when the delay amount of the SFN wave is −Tg or less or + Tg or more, the delay amount of the SFN wave is increased in order to promote the possibility of reception performance degradation. The display color is different from that when it is well within ± Tg.

本実施例において、ＦＦＴ窓位置の設定可能範囲を８段階として説明したが、設定可能範囲、分解能を上げても同様の効果が得られることは言うまでもない。また、演算方法も単なる平均以外に適切な近似式を用いることも可能であり、表示方法についても横型のレベルバー表示以外の円形、縦型などの他の形状を用いても同様の効果が得られることは言うまでも無い。 In this embodiment, the settable range of the FFT window position has been described as eight stages, but it goes without saying that the same effect can be obtained even if the settable range and resolution are increased. It is also possible to use an appropriate approximation formula other than mere averaging for the calculation method, and the same effect can be obtained by using other shapes such as a circular shape and a vertical shape other than the horizontal level bar display as the display method. Needless to say.

以上のように、本発明にかかるＯＦＤＭ受信装置は、ＳＦＮが運用されている受信エリアで受信障害が発生した場合に、その原因が不適切なアンテナ設置を含む受信システムの要因かＯＦＤＭ受信装置の故障かを容易に切り分けが可能な機能を備えた安価なＯＦＤＭ受信装置を提供できるという利点を有し、地上波デジタル放送を受信するＴＶ、ＳＴＢ（セット・トップ・ボックス）、ハードディスクおよびＤＶＤレコーダーなどのＯＦＤＭ受信装置として有用である。 As described above, in the OFDM receiver according to the present invention, when a reception failure occurs in the reception area where the SFN is operated, the cause of the reception system including improper antenna installation is the cause of the OFDM receiver. TV, STB (set top box), hard disk, DVD recorder, etc. that have the advantage of being able to provide an inexpensive OFDM receiver with a function that can easily isolate a failure. It is useful as an OFDM receiver.

本発明の受信装置の構成を示す図The figure which shows the structure of the receiver of this invention 本発明のＯＦＤＭ受信装置の画像表示を示す概略図Schematic showing the image display of the OFDM receiver of the present invention 従来の受信装置の構成を示す図The figure which shows the structure of the conventional receiver

Explanation of symbols

１選局回路
２ＡＤコンバータ
３ＡＦＣ回路
４同期回路
５ＦＦＴ回路
６誤り訂正回路
７システムＬＳＩ
８演算回路
９表示回路
１０ＯＦＤＭ受信装置本体
１１表示画面
１２ＦＦＴ窓位置インジケータ
１３ＦＦＴ窓位置インジケータ
１４ＦＦＴ窓位置インジケータ DESCRIPTION OF SYMBOLS 1 Channel selection circuit 2 AD converter 3 AFC circuit 4 Synchronization circuit 5 FFT circuit 6 Error correction circuit 7 System LSI
DESCRIPTION OF SYMBOLS 8 Arithmetic circuit 9 Display circuit 10 OFDM receiver main body 11 Display screen 12 FFT window position indicator 13 FFT window position indicator 14 FFT window position indicator

Claims

A guard correlation with a plurality of SFNs transmitted at the same frequency as the main broadcast wave is detected, the FFT window position is appropriately controlled based on the detected guard correlation, and the FFT obtained by these controls is obtained. An OFDM receiver comprising: means for numerically outputting window position information; and means for calculating and displaying the output FFT window position information.

Detects the guard correlation between the main broadcast wave and a plurality of SFN waves transmitted at the same frequency, and feeds back the FFT window position based on the detected guard correlation so that the error of the received signal is minimized. An OFDM receiving apparatus comprising: means for performing control, numerically outputting FFT window position information obtained by these controls, and means for calculating and displaying the output FFT window position information.

The guard correlation between the main broadcast wave and a plurality of SFN waves transmitted at the same frequency is detected, and the FFT window position is appropriately controlled based on the detected guard correlation. When the delay amount between the FFT window position information is converted into a numerical value and the SFN wave and the main broadcast wave are sufficiently smaller than the guard interval, the FFT window position information fluctuates within a certain range, and the delay amount An OFDM receiving apparatus comprising means for calculating the presence of an SFN wave by calculating based on a characteristic that becomes a constant value when is larger than the guard interval.

Detects the guard correlation between the main broadcast wave and a plurality of SFN waves transmitted at the same frequency, and feeds back the FFT window position based on the detected guard correlation so that the error of the received signal is minimized. Means for numerically outputting the FFT window position information obtained by these controls, and FFT window position information when the delay amount between the SFN wave and the main broadcast wave is sufficiently smaller than the guard interval. An OFDM receiving apparatus comprising means for calculating the presence of an SFN wave by calculating based on a characteristic that becomes a constant value when fluctuates within a certain range and the delay amount is larger than the guard interval.

The OFDM receiver according to claim 3, wherein when an SFN wave is present, the color of the indicator displayed in the image changes.

The OFDM receiver according to claim 4, wherein when an SFN wave is present, the color of the indicator displayed in the image changes.

If there is an SFN wave, the color of the series of indicators divided into at least three parts displayed in the image changes, and if the delayed wave arrives earlier in time than the main broadcast wave, it will be at the center. The indicator located on the left side is emphasized, and when the delayed wave arrives later than the main broadcast wave, the indicator located on the right side of the center is emphasized. OFDM receiver.