JP3550326B2 - Digital broadcast receiver - Google Patents

Description

とする。
【００３２】
このときｍ番目の受信アンテナ（ブランチ）での受信信号を
【００３３】
【数２】

とすると、受信信号は
【００３４】
【数３】

と書き表す事ができる。
ここで
【００３５】
【数４】

はｍ番目の受信アンテナでの白色雑音である。
【００３６】
それぞれのアンテナで受信された信号は重み係数を乗算されて加算される。
加算後の受信信号を
【００３７】
【数５】

とすると次式で表される。
【００３８】
【数６】

ここでｍ番目のブランチの重み係数は
【００３９】
【数７】

である。
【００４０】
受信機では上記受信信号をＤＦＴ処理する事で復調を行う。
したがって、ＤＦＴ出力信号を
【００４１】
【数８】

とすると、受信信号は次式で表現できる。
【００４２】
【数９】

各受信アンテナの重み係数の重みベクトルｗは
【００４３】
【数１０】

とする。
【００４４】
本発明に係るデジタル放送受信機では、受信した各ブランチ信号をＤＦＴ前に合成し、ＤＦＴ後のＳＮＲを最大にするように重み係数を求める事になる。つまり受信信号の共分散行列を求め、その行列の最大の固有値に対する固有ベクトルを重み係数Ｗとすればよい。
【００４５】
以下、図面を参照して本発明のデジタル放送受信機の実施形態について説明する。
【００４６】
図１は本発明の第１の実施形態で、ダイバーシチＯＦＤＭ受信機のシステムの構成を示す構成図である。この例では２ブランチ（アンテナ）のダイバーシチ受信システムを示しているが、当然に、これより多いブランチのシステムでも同様に適用できる。
【００４７】
以下、動作を説明する。
【００４８】
受信アンテナ１１ａ、ｂにより受信した信号はＲＦ信号としてチューナ部１３ａ、ｂに入力する。チューナ部１３ａ、ｂでは希望するチャンネルを選局し、ＩＦ信号またはベースバンド信号を出力する。出力されたＩＦ信号またはベースバンド信号はＡＤＣ１４ａ、ｂによりサンプリング及び量子化され、デジタル信号に変換される。
【００４９】
デジタル化された受信信号は合成回路１６により重み付けされた後、加算され、復調器へ出力される。合成回路１６により加算された信号はＯＦＤＭ復調部１７にてＯＦＤＭ復調を行う。この例ではチューナ部１３ａ、ｂの出力端子よりＩＦ信号が出力する場合について説明する。ベースバンド信号出力でも同様の効果が得られる。
【００５０】
受信アンテナ１１ａ、ｂにより受信したＲＦ信号は可変遅延器１２ａ、ｂを通して受信チューナ１３ａ、ｂに入力される。ここでは、それぞれ独立に受信された信号の遅延時間を制御部２０により変化させて受信信号を生成している。また、制御部２０の遅延時間の変化量及び変化する速度は外部の制御信号入力端子２１により入力された制御信号により設定することができる。
【００５１】
受信チューナ１３ａ、ｂで選局され、ＡＤＣ１４ａ、ｂによりデジタル信号に変換された信号は、係数計算部１５により最適な各ブランチごとの重み係数を計算し、合成器１６により合成され、合成された信号はＯＦＤＭ復調部１７にて復調され、復調された信号は復号部１８にて複合処理を行い、ＴＳ信号を出力端子１９より出力する。
【００５２】
復号部１８では、送信側の処理の逆処理が行われる。すなわち周波数デインターリーブ処理、時間デインターリーブ処理、デマッピング処理、デパンクチュア処理、ビタビデコード処理、リードソロモンデコード処理、逆拡散処理等が行われて、トランスポートストリーム（ＴＳ信号）が出力される。
【００５３】
ここで、図４に図１における合成器１６のブロック図を示す。
【００５４】
図４において、ＡＤＣ１４ａ、ｂによりデジタル信号に変換された受信信号を合成部１６の内部の乗算器４１ａ、ｂにより重み係数ｗ１、ｗ２を乗算し、加算器４２で加算する。重み係数ｗ１、ｗ２は受信信号より重み係数計算部１５により求められる係数である。
【００５５】
前記合成器１６により生成された信号はＯＦＤＭ復調部により復調される。復調された信号は後段の復号部１８により復号され出力端子１９より出力される。
【００５６】
図５に図１におけるＯＦＤＭ復調部１７ブロック図を示す。
【００５７】
図５において、ＡＤＣ１４ａ、ｂの出力信号はＯＦＤＭ復調部の入力端子５１よりデジタル信号として入力され、ＩＱ復調部５２により復調されベースバンド信号に変換される。変換されたデジタルのベースバンド信号はガードインターバル除去回路５３により送信側で付加されたガードインターバル信号を除去する。
【００５８】
除去された信号は、有効シンボル信号のみとなり後段のＦＦＴ処理回路５４に渡される。ＦＦＴ処理回路５４により高速フーリエ変換が行われ、時間軸上の信号より周波数軸上の信号に変換される。変換された信号は後段の波形等化回路５５にわたされ処理される。等化されたデータは、データ出力端子５６から出力される。出力端子５６より出力された信号は、図１における復号部１８に渡され、処理される。
【００５９】
図６は、図１における可変遅延器１２ａ、ｂの素子の構造を示す図である。
【００６０】
入力端子６０より入力された信号は基板６１の上方の形成されたストリップライン６２より信号を伝達し、出力端子６３より出力する。
【００６１】
可変遅延器１２ａ、ｂはＢＳＴ（Ｂａ、Ｓｒ、Ｔｉの酸化物）や液晶を用いた誘電体６８を上部電極６６と下部電極６７ではさんだ形で構成されており、外部の制御回路６４より制御電圧を電圧入力端子６５ａ、ｂより与えることで、誘電体素子６８の誘電率を変化させ、可変遅延器１２ａ、ｂの信号伝達時間を制御するようにしている。素子は基板６９上に形成されている。
【００６２】
図７は、図１におけるチューナ部１３ａ、ｂのブロック図である。
【００６３】
受信アンテナより受信された信号は入力端子７０ａ、ｂにより入力され増幅器７２ａ、ｂにより諸所定のレベル迄増幅され乗算器７３ａ、ｂに入力され、選局用ローカル信号を分配する分配器７８からのローカル信号と乗算を行い、希望の周波数を選択する。選局用ローカル信号は選局制御部８２より指定された希望の周波数に応じてＰＬＬ回路を制御し、所定の周波数を発生する。乗算器７３ａ、ｂの出力信号は後段のフィルタ７４ａ、ｂにより希望する周波数帯のみを選択し、隣接の不要な信号成分を除去して出力する。選択された信号は後段の乗算器７５ａ、ｂにより中間周波数（ＩＦ信号）へ変換される。
【００６４】
中間周波数（ＩＦ信号）への変換用のローカル信号は信号源８１により発生し、分配器７９により分配する。生成されたＩＦ信号は増幅器７６ａ、ｂを通して最適レベル迄増幅して出力端子７７ａ、ｂより出力する。
【００６５】
図８は、図１における計数計算部１５の構成を示すブロック図である。
【００６６】
当該係数計算部１５は、最大比合成用計算部１０３と選択合成用計算部１０４と利得合成用計算部１０５の３種の計算部と、これら３種の計算部の入出力信号を切換える選択部１０２、１０７と、該選択部を制御する制御部１０６よりなる。
【００６７】
受信状態に応じてこれら３種の計算部の中から最も適切な計算部の計算結果を出力する。尚、この計算部は必要に応じて更に増やしても良い。
各ブランチの受信信号は入力端子１００ａ、ｂより入力され、受信状態に応じての係数計算方式を選択する。
【００６８】
図９は、図８における最大比合成用計算部１０３のブロック図である。
【００６９】
図８における選択部１０２で選択された信号は、まず共分散行列計算部９１により共分散行列が計算される。その結果は、固有ベクトル計算部９２により前記行列の最大の固有値に対する固有ベクトルを求められる。計算結果は出力端子９３ａ、９３ｂより出力される。
【００７０】
出力された信号は図８における選択部１０７を経由して、図４の係数入力端子４３ａ、ｂより入力され、乗算器４１ａ、ｂへ渡され、入力端子４０ａ、ｂより入力された受信信号と掛け合わされる。
【００７１】
図１０は、図８における上記選択合成用計算部１０４のブロック図である。
【００７２】
図８における選択部１０２で選択された信号は、電力計算部１１２によりそれぞれのブランチの電力を計算する。後段の比較回路１１３は前記電力計算部１１２の計算結果により最大電力を持つブランチを選択し、同時に最大電力をす有するブランチが選択できるように係数を発生し、出力端子１１４ａ、ｂより出力する。
【００７３】
図３は、本発明の第２の実施形態を示すブロック図である。
【００７４】
アンテナ１１ａ、ｂにより受信した信号は受信チューナ１３ａ、ｂにより選局され、選局され信号は遅延器３１ａ、ｂにより遅延され、ＡＤＣ１４ａ、ｂによりデジタル信号に変換された信号は係数計算部１５により最適な各ブランチごとの重み係数を計算し、合成器１６により合成され、合成された信号はＯＦＤＭ復調部１７にて復調され、復調された信号は復号部１８にて複合処理を行い、ＴＳ信号を出力端子１９より出力する。
【００７５】
ここでは、それぞれ独立に受信された信号の遅延時間を制御部２０により変化させて受信信号を生成している。また制御部２０の遅延時間の変化量及び変化する速度は外部の制御信号入力端子２１により入力された制御信号により設定することができる。
【００７６】
図１１は、本発明の第３の実施形態を示すブロック図である。
【００７７】
アンテナ１１ａ、ｂにより受信した信号は受信チューナ１３ａ、ｂにより選局され、ＡＤＣ１４ａ、ｂに入力され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信号はそれぞれ独立に遅延器１２１ａ、ｂにより遅延される。遅延された信号は係数計算部１５により最適な各ブランチごとの重み係数を計算し、合成器１６により合成され、合成された信号はＯＦＤＭ復調部１７にて復調され、復調された信号は復号部１８にて複合処理を行い、ＴＳ信号を出力端子１９より出力する。
【００７８】
前記遅延器の遅延時間は制御部１２２により制御されており、制御部１２２の遅延時間の変化量及び変化する速度は外部の制御信号入力端子２１により入力された制御信号により設定することができる。
【００７９】
以上の本発明の説明に於いて、受信ブランチ数を２ブランチで行ったが、３ブランチ以上の構成を取ることも可能であり、その効果はブランチ数が増大するほど大きい。
【００８０】
【発明の効果】
以上説明したように、本発明の受信装置によると従来のアンテナダイバーシチの様にハードウエアが複雑にならず、移動受信時に発生するマルチパスフェージングを克服するものである。
【００８１】
本発明は将来期待されているデジタル放送や、広帯域通信等の高速移動受信を非常に効率良く実現する手段であり、小型で低消費電力な受信システムを実現することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態におけるデジタル放送受信機の構成を示すブロック図である。
【図２】従来のデジタル放送受信機の構成を示すブロック図である。
【図３】本発明の別の第２の実施形態におけるデジタル放送受信機の構成を示すブロック図である。
【図４】本発明に係る合成器の構成を示すブロック図である。
【図５】本発明に係るＯＦＤＭ復調部の構成を示すブロック図である。
【図６】本発明に係る可変遅延器の構成を示すブロック図である。
【図７】本発明に係る選局部の構成を示すブロック図である。
【図８】本発明に係る計数部の構成を示すブロック図である。
【図９】本発明に係る計数部における最大比合成回路のの構成を示すブロック図である。
【図１０】本発明に係る計数部における選択利得合成回路の構成を示すブロック図である。
【図１１】本発明の第３の別の実施形態におけるデジタル放送受信機の構成を示すブロック図である。
【符号の説明】
１１ａ、ｂ 受信アンテナ
１２ａ、ｂ 可変遅延器
１３ａ、ｂ 選局部（チューナ）
１４ａ、ｂ ＡＤＣ
１５ 係数計算部
１６ 合成部
１７ ＯＦＤＭ復調部
１８ 復号部
１９ 出力端子
２０ 遅延制御回路
２１ 制御信号入力端子
２２ 共通発振器（ローカルオシレータ）
２３ａ、ｂ チューナ
２４ａ、ｂ ＯＦＤＭ復調部
２５ａ、ｂ 復号部
２６ 誤り率計算部
２７ 選択回路
２８ 出力端子
３１ａ、ｂ 遅延器
３４ 出力端子
４０ａ、ｂ 信号入力端子
４１ａ、ｂ 乗算器
４２ 加算器
４３ａ、ｂ 係数入力端子
４４ 出力端子
５１ 信号入力端子
５２ ＩＱ復調回路
５３ ガードインターバル除去回路
５４ ＦＦＴ処理回路
５５ 波形等化回路
５６ 出力端子
５７ 同期処理回路
６０ 信号入力端子
６１ 可変遅延器
６２ ストリップライン
６３ 出力端子
６４ 制御回路
６５ａ、ｂ 制御電圧印加端子
６６ 上部電極
６７ 下部電極
６８ 誘電体素子
６９ 基板
７０ａ、ｂ 入力端子
７２ａ、ｂ 増幅器
７３ａ、ｂ 第１ミキサー
７４ａ、ｂ フィルター
７５ａ、ｂ 第２ミキサー
７６ａ、ｂ 増幅器
７７ａ、ｂ 出力端子
７８ 分配器
７９ 分配器
８０ ＰＬＬ回路
８１ 発振器
８２ 選局制御部
８３ 水晶発振器
９０ａ、ｂ 入力端子
９１ 共分散行列
９２ 固有ベクトル計算部
９３ａ、ｂ 出力端子
１００ａ、ｂ 出力端子
１０１ 制御信号入力端子
１０２ 選択回路１
１０３ 係数計算回路１
１０４ 係数計算回路２
１０５ 係数計算回路３
１０６ 制御部
１０７ 選択回路２
１０８ａ、ｂ 出力端子
１１０ａ、ｂ 入力端子
１１２ 電力計算回路
１１３ 比較回路
１１４ａ、ｂ 出力端子
１２１ａ、ｂ 遅延器
１２２ 制御回路
１２３ 制御端子[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a digital broadcast receiving apparatus, and more particularly to a digital broadcast receiving apparatus that can be suitably used in a poor reception environment such as mobile reception and portable reception.
[0002]
[Prior art]
In terrestrial digital broadcasting, digitization is performed to realize effective use of SFN (Single Frequency Network), MFN (Multi Frequency Network) and bands. According to this, it is possible to broadcast one program for HDTV and three programs for SDTV using a 6 MHz area. At the same time, high-quality name broadcasting and data broadcasting will be realized.
[0003]
In digital broadcasting, video / audio information is compressed by the MPEG2 system, and the compressed video, audio information, and data broadcast are multiplexed to generate a transport stream (TS). The generated TS signal is transmitted by a digital modulation method.
[0004]
In the case of terrestrial digital broadcasting, in Europe, COFDM (Coded Orthogonal Frequency Division Multiplexing) is used as a transmission system, and in Japan, BST-OFDM (Band Segmented Transmission-Orthogonal Frequency Multiplexing system is used, and either of the orthogonal frequency division system and the orthogonal frequency division system is used). (OFDM system). The OFDM system is a multi-carrier transmission system using a plurality of carriers simultaneously, and the respective carriers are orthogonal to each other and are modulated by DQPSK, QPSK, 16QAM, and 64QAM. Do you use about 1,400 carriers for digital terrestrial broadcasting in Japan? With 5600 lines, OFDM modulation and OFDM demodulation are performed by inverse Fourier transform and Fourier transform, respectively.
[0005]
In actual transmitters and receivers, 2K points to 8K points of I-DFT (Inverse-Discrete Fourier Transformation) processing and DFT (Discrete Fourier Transformation) processing are performed.
[0006]
Unlike terrestrial digital broadcasting, unlike terrestrial broadcasting, radio waves are emitted horizontally from the transmitting tower, and reflected waves are generated by obstacles such as buildings and mountains, causing ghosts and errors in digitally modulated signals. This causes the audio signal to break, and the reception quality is significantly degraded. Signal degradation due to noise can be corrected by error correction, and the receiver can reproduce video / audio without error.
[0007]
As described above, a buffer area is provided in the OFDM system in order to absorb the influence of interference due to ghosts and multipaths, so that even if a delayed wave exists, information is not broken. This buffer area is called a guard interval. If the delay time of the delay wave of the received signal does not exceed the time of the guard interval, no intersymbol interference occurs, so that the error can be corrected by the error correction circuit. The guard interval signal is set to 1/4, 1/8, 1/16, and 1/32 of the total transmission signal, which corresponds to about 8 microseconds to 250 microseconds.
[0008]
Generally, in mobile reception in terrestrial broadcasting, selective fading occurs due to multipath fading, and a digitally modulated signal is extremely deteriorated, causing information errors. In digital broadcasting, such errors are reduced by adopting the BST-OFDM scheme to enable mobile reception.
[0009]
In particular, this method can correct a degraded signal by interleaving, convolutional code, and error correction even when selective fading occurs.
[0010]
However, under multipath fading, which has terrible selectivity and extremely slow time variation, the signal may not be corrected even by using the above method.
[0011]
In order to cope with such poor transmission paths, antenna diversity using a plurality of receiving antennas has been proposed. FIG. 2 shows a diversity receiving method using two conventional antennas.
[0012]
According to this method, a radio wave transmitted from a broadcasting station is received by two antennas 11a and 11b, and a desired frequency is selected by tuners 23a and 23b. The selected IF signal or baseband signal is converted to a digital signal by analog-digital conversion circuits (ADCs) 14a and 14b. The digitized signal is demodulated by the OFDM demodulators 17a and 17b and decoded by the decoders 18a and 18b.
[0013]
The error rate calculator 26 calculates the error rate from the signal received and demodulated in each branch, and sends a control signal to the selection circuit 27 so as to select a branch with a small number of errors. The signal decoded by the decoders 18a and 18b is selected by the selection circuit 27 with the smaller error, and the TS signal is output.
[0014]
As described above, by selecting a branch having a small number of errors from the demodulated signal, stable reception can be performed even when the radio wave environment such as mobile reception is not good.
[0015]
However, the above-mentioned diversity receiving method requires OFDM demodulation processing in each branch, and has a disadvantage that the receiving system becomes complicated. In addition, as the number of branches increases, the size of the system increases, and the power consumption also increases.
[0016]
[Problems to be solved by the invention]
As described above, multipath fading occurs in mobile reception, resulting in transmission path characteristics accompanied by selective fading, and the frequency characteristics of the transmission path deteriorate while fluctuating with time.
[0017]
In the OFDM system, data is divided into subcarriers, and error correction and interleaving are performed by encoding, so that errors in received data can be corrected even if transmission characteristics deteriorate due to multipath delay waves.
[0018]
However, mobile reception has a problem that an environment where direct waves cannot be received and a reception electric field are reduced. In order to solve such a problem, antenna diversity for receiving with a plurality of antennas has been proposed, which is compatible with multipath fading.
[0019]
FIG. 2 is a configuration diagram of a conventional space diversity system that receives an OFDM reception signal.
[0020]
The signal received by the receiving antenna 11a is converted into a digital signal by a tuner 23a for channel selection and an analog-digital converter (ADC) 14a. The received signal converted into a digital signal is OFDM-demodulated by the OFDM demodulation unit 24a, and is passed to the subsequent-stage decoding unit 25a. The decoding unit 25a performs an inverse process of the encoding performed on the transmission side and outputs a signal. This output signal is passed to the selection circuit 27. Similarly, the signal received by the receiving antenna 11b is independently processed according to the same procedure as the above processing. The signal received and demodulated in each branch is selected by the selection circuit 27 so that data having the least error between subcarriers is selected.
[0021]
However, as described above, in the conventional diversity, it is necessary to perform OFDM demodulation on signals received by a plurality of antennas, and to synthesize optimal data for each sub-channel. That is, the number of OFDM demodulation units is required as many as the number of antennas (branches), and there is a disadvantage that the circuit becomes large-scale, and there is a problem that power consumption increases with an increase in the number of branches.
[0022]
SUMMARY OF THE INVENTION The present invention solves this problem by processing and combining signals received by a plurality of antennas before OFDM demodulation, thereby improving reception signal characteristics without increasing hardware complexity. Machine.
[0023]
[Means for Solving the Problems]
The present invention has the following configuration in order to solve the above problems.
[0024]
According to a first aspect of the present invention, in a digital broadcast receiver for receiving an orthogonal frequency division multiplexed signal with a plurality of antennas, a variable delay unit for signals received by the plurality of antennas and a signal from the variable delay unit are combined. Synthesizing means, orthogonal frequency division multiplexing signal demodulating means for demodulating the synthesized signal, decoding means for decoding the demodulated signal, and coefficient calculation for obtaining a weight coefficient from signals received by the plurality of antennas Means, the variable delay means, by a separately input control signal, controls the speed at which the delay time changes, the coefficient calculating means, the covariance matrix of the received signals from the plurality of antennas Then, an eigenvector for the largest eigenvalue of the matrix is used as a weight coefficient .
[0025]
The second invention of the present application is further characterized by further comprising a plurality of tuning means for tuning the same station, and a single local oscillation means common to the plurality of tuning means .
[0026]
The third invention of the present application is characterized in that the variable delay means is constituted by a dielectric element, and changes a dielectric constant by voltage control .
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
First, an outline of the digital broadcast receiver of the present invention will be described. In the present invention, broadcast waves are independently received by N receiving antennas.
[0030]
It is assumed that a multipath having L paths has arrived at each receiving antenna, and the complex amplitude of the l-th path arriving at the m-th receiving antenna is represented by
(Equation 1)

And
[0032]
At this time, the received signal at the m-th receiving antenna (branch) is
(Equation 2)

Then, the received signal becomes
(Equation 3)

Can be written.
Here [0035]
(Equation 4)

Is the white noise at the m-th receiving antenna.
[0036]
The signals received by each antenna are multiplied by a weighting factor and added.
The received signal after the addition is
(Equation 5)

Is represented by the following equation.
[0038]
(Equation 6)

Here, the weight coefficient of the m-th branch is
(Equation 7)

It is.
[0040]
The receiver performs DFT processing on the received signal to perform demodulation.
Therefore, the DFT output signal is
(Equation 8)

Then, the received signal can be expressed by the following equation.
[0042]
(Equation 9)

The weight vector w of the weight coefficient of each receiving antenna is
(Equation 10)

And
[0044]
In the digital broadcast receiver according to the present invention, the received branch signals are combined before the DFT, and the weight coefficient is determined so as to maximize the SNR after the DFT. That is, the covariance matrix of the received signal is obtained, and the eigenvector corresponding to the largest eigenvalue of the matrix may be set as the weight coefficient W.
[0045]
Hereinafter, an embodiment of a digital broadcast receiver of the present invention will be described with reference to the drawings.
[0046]
FIG. 1 is a configuration diagram showing a configuration of a system of a diversity OFDM receiver according to a first embodiment of the present invention. In this example, a two-branch (antenna) diversity receiving system is shown, but it goes without saying that a system with more branches than this can be similarly applied.
[0047]
Hereinafter, the operation will be described.
[0048]
The signals received by the receiving antennas 11a and 11b are input to the tuners 13a and 13b as RF signals. The tuners 13a and 13b select a desired channel and output an IF signal or a baseband signal. The output IF signal or baseband signal is sampled and quantized by the ADCs 14a and 14b, and is converted into a digital signal.
[0049]
The digitized received signal is weighted by the combining circuit 16, added, and output to the demodulator. The OFDM demodulation unit 17 performs OFDM demodulation on the signal added by the combining circuit 16. In this example, a case where an IF signal is output from the output terminals of the tuners 13a and 13b will be described. Similar effects can be obtained with the baseband signal output.
[0050]
The RF signals received by the receiving antennas 11a and 11b are input to the receiving tuners 13a and 13b through the variable delay units 12a and 12b. Here, the control unit 20 changes the delay time of each independently received signal to generate a received signal. Further, the amount of change and the changing speed of the delay time of the control unit 20 can be set by a control signal input from an external control signal input terminal 21.
[0051]
The signals selected by the reception tuners 13a and 13b and converted into digital signals by the ADCs 14a and 14b are calculated by the coefficient calculation unit 15 to calculate the optimum weight coefficient for each branch, and are synthesized by the synthesizer 16 and synthesized. The signal is demodulated by an OFDM demodulation unit 17, and the demodulated signal is subjected to compound processing by a decoding unit 18, and a TS signal is output from an output terminal 19.
[0052]
In the decoding unit 18, the reverse process of the process on the transmission side is performed. That is, frequency deinterleave processing, time deinterleave processing, demapping processing, depuncture processing, Viterbi decoding processing, Reed-Solomon decoding processing, despreading processing, and the like are performed, and a transport stream (TS signal) is output.
[0053]
Here, FIG. 4 shows a block diagram of the combiner 16 in FIG.
[0054]
In FIG. 4, received signals converted into digital signals by the ADCs 14a and 14b are multiplied by weighting factors w1 and w2 by multipliers 41a and 41b inside the combining unit 16, and added by an adder 42. The weight coefficients w1 and w2 are coefficients obtained by the weight coefficient calculator 15 from the received signal.
[0055]
The signal generated by the combiner 16 is demodulated by an OFDM demodulator. The demodulated signal is decoded by the decoding unit 18 at the subsequent stage and output from the output terminal 19.
[0056]
FIG. 5 shows a block diagram of the OFDM demodulation unit 17 in FIG.
[0057]
In FIG. 5, output signals of the ADCs 14a and 14b are input as digital signals from an input terminal 51 of an OFDM demodulation unit, demodulated by an IQ demodulation unit 52, and converted into baseband signals. The guard interval removing circuit 53 removes the guard interval signal added on the transmitting side from the converted digital baseband signal.
[0058]
The removed signal becomes only an effective symbol signal and is passed to the FFT processing circuit 54 in the subsequent stage. Fast Fourier transform is performed by the FFT processing circuit 54, and the signal on the time axis is converted into a signal on the frequency axis. The converted signal is passed to a subsequent-stage waveform equalization circuit 55 for processing. The equalized data is output from the data output terminal 56. The signal output from the output terminal 56 is passed to the decoding unit 18 in FIG. 1 and processed.
[0059]
FIG. 6 is a diagram showing the structure of the elements of the variable delay units 12a and 12b in FIG.
[0060]
The signal input from the input terminal 60 is transmitted from the strip line 62 formed above the substrate 61 and output from the output terminal 63.
[0061]
The variable delay devices 12a and 12b are formed by sandwiching a dielectric 68 using BST (oxide of Ba, Sr, Ti) or liquid crystal between an upper electrode 66 and a lower electrode 67, and controlled by an external control circuit 64. By applying a voltage from the voltage input terminals 65a and 65b, the dielectric constant of the dielectric element 68 is changed, and the signal transmission time of the variable delay units 12a and 12b is controlled. The element is formed on a substrate 69.
[0062]
FIG. 7 is a block diagram of the tuner units 13a and 13b in FIG.
[0063]
Signals received from the receiving antennas are input to input terminals 70a and 70b, amplified to predetermined levels by amplifiers 72a and 72b, input to multipliers 73a and 73b, and output from a splitter 78 for distributing local signals for channel selection. Multiply with the local signal and select the desired frequency. The tuning local signal controls a PLL circuit according to a desired frequency specified by the tuning control unit 82 to generate a predetermined frequency. From the output signals of the multipliers 73a and 73b, only the desired frequency band is selected by the subsequent filters 74a and 74b, and adjacent unnecessary signal components are removed and output. The selected signal is converted to an intermediate frequency (IF signal) by multipliers 75a and 75b at the subsequent stage.
[0064]
A local signal for conversion to an intermediate frequency (IF signal) is generated by a signal source 81 and distributed by a distributor 79. The generated IF signal is amplified to an optimum level through amplifiers 76a and 76b and output from output terminals 77a and 77b.
[0065]
FIG. 8 is a block diagram showing the configuration of the count calculation unit 15 in FIG.
[0066]
The coefficient calculation unit 15 includes three types of calculation units, a maximum ratio synthesis calculation unit 103, a selection synthesis calculation unit 104, and a gain synthesis calculation unit 105, and a selection unit that switches input / output signals of these three types of calculation units. And a control unit 106 for controlling the selection unit.
[0067]
It outputs the calculation result of the most appropriate calculation unit among these three types of calculation units according to the reception state. It should be noted that this calculation unit may be further increased as necessary.
The received signal of each branch is input from the input terminals 100a and 100b, and selects a coefficient calculation method according to the reception state.
[0068]
FIG. 9 is a block diagram of the maximum ratio combining calculation unit 103 in FIG.
[0069]
The covariance matrix of the signal selected by the selection unit 102 in FIG. As a result, an eigenvector for the largest eigenvalue of the matrix is obtained by the eigenvector calculation unit 92. The calculation result is output from output terminals 93a and 93b.
[0070]
The output signal is input from coefficient input terminals 43a and 43b in FIG. 4 via selector 107 in FIG. 8 and passed to multipliers 41a and 41b. Multiplied.
[0071]
FIG. 10 is a block diagram of the selection / combination calculation unit 104 in FIG.
[0072]
The power of each branch of the signal selected by the selection unit 102 in FIG. 8 is calculated by the power calculation unit 112. The comparison circuit 113 at the subsequent stage selects a branch having the maximum power based on the calculation result of the power calculation unit 112, and at the same time, generates a coefficient so that the branch having the maximum power can be selected and outputs the coefficient from the output terminals 114a and 114b.
[0073]
FIG. 3 is a block diagram showing a second embodiment of the present invention.
[0074]
The signals received by the antennas 11a and 11b are selected by the reception tuners 13a and 13b, the selected signals are delayed by the delay units 31a and 31b, and the signals converted into the digital signals by the ADCs 14a and 14b are converted by the coefficient calculation unit 15. An optimal weighting coefficient for each branch is calculated, combined by a combiner 16, the combined signal is demodulated by an OFDM demodulation unit 17, and the demodulated signal is subjected to compound processing by a decoding unit 18, and a TS signal Is output from the output terminal 19.
[0075]
Here, the control unit 20 changes the delay time of each independently received signal to generate a received signal. In addition, the amount of change and the speed of change of the delay time of the control unit 20 can be set by a control signal input from an external control signal input terminal 21.
[0076]
FIG. 11 is a block diagram showing a third embodiment of the present invention.
[0077]
The signals received by the antennas 11a and 11b are selected by the receiving tuners 13a and 13b, input to the ADCs 14a and 14b, and converted into digital signals. The signals converted into digital signals are independently delayed by the delay units 121a and 121b. The delayed signal is calculated by a coefficient calculator 15 to calculate an optimal weighting coefficient for each branch, and is combined by a combiner 16. The combined signal is demodulated by an OFDM demodulator 17 and the demodulated signal is decoded by a decoder. The composite processing is performed at 18, and the TS signal is output from the output terminal 19.
[0078]
The delay time of the delay unit is controlled by a control unit 122, and the amount of change and the speed of change of the delay time of the control unit 122 can be set by a control signal input from an external control signal input terminal 21.
[0079]
In the above description of the present invention, the number of reception branches is two, but a configuration of three or more branches is possible, and the effect is greater as the number of branches increases.
[0080]
【The invention's effect】
As described above, according to the receiving apparatus of the present invention, the hardware is not complicated as in the conventional antenna diversity, and the multipath fading that occurs during mobile reception is overcome.
[0081]
The present invention is a means for extremely efficiently realizing high-speed mobile reception such as digital broadcasting and broadband communication expected in the future, and can realize a small-sized and low-power-consumption reception system.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a digital broadcast receiver according to a first embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of a conventional digital broadcast receiver.
FIG. 3 is a block diagram illustrating a configuration of a digital broadcast receiver according to another second embodiment of the present invention.
FIG. 4 is a block diagram showing a configuration of a synthesizer according to the present invention.
FIG. 5 is a block diagram illustrating a configuration of an OFDM demodulation unit according to the present invention.
FIG. 6 is a block diagram showing a configuration of a variable delay device according to the present invention.
FIG. 7 is a block diagram illustrating a configuration of a tuning unit according to the present invention.
FIG. 8 is a block diagram illustrating a configuration of a counting unit according to the present invention.
FIG. 9 is a block diagram showing a configuration of a maximum ratio combining circuit in the counting section according to the present invention.
FIG. 10 is a block diagram showing a configuration of a selective gain combining circuit in the counting section according to the present invention.
FIG. 11 is a block diagram illustrating a configuration of a digital broadcast receiver according to a third different embodiment of the present invention.
[Explanation of symbols]
11a, b Receiving antennas 12a, b Variable delay units 13a, b Tuner
14a, b ADC
Reference Signs List 15 coefficient calculation unit 16 synthesis unit 17 OFDM demodulation unit 18 decoding unit 19 output terminal 20 delay control circuit 21 control signal input terminal 22 common oscillator (local oscillator)
23a, b Tuner 24a, b OFDM demodulation unit 25a, b decoding unit 26 error rate calculation unit 27 selection circuit 28 output terminal 31a, b delay unit 34 output terminal 40a, b signal input terminal 41a, b multiplier 42 adder 43a, b coefficient input terminal 44 output terminal 51 signal input terminal 52 IQ demodulation circuit 53 guard interval elimination circuit 54 FFT processing circuit 55 waveform equalization circuit 56 output terminal 57 synchronization processing circuit 60 signal input terminal 61 variable delay unit 62 stripline 63 output terminal 64 control circuit 65a, b control voltage application terminal 66 upper electrode 67 lower electrode 68 dielectric element 69 substrate 70a, b input terminal 72a, b amplifier 73a, b first mixer 74a, b filter 75a, b second mixer 76a, b Amplifier 77a, b Output terminal 78 Distributor 79 Distributor 80 PLL Circuit 81 Oscillator 82 Tuning control unit 83 Crystal oscillator 90a, b Input terminal 91 Covariance matrix 92 Eigenvector calculation unit 93a, b Output terminal 100a, b Output terminal 101 Control signal input terminal 102 Selection circuit 1
103 Coefficient calculation circuit 1
104 coefficient calculation circuit 2
105 Coefficient calculation circuit 3
106 control unit 107 selection circuit 2
108a, b output terminal 110a, b input terminal 112 power calculation circuit 113 comparison circuit 114a, b output terminal 121a, b delay unit 122 control circuit 123 control terminal

Claims (3)

In a digital broadcast receiver that receives an orthogonal frequency division multiplexed signal with a plurality of antennas,
Variable delay means for signals received by the plurality of antennas,
Combining means for combining signals from the variable delay means;
Orthogonal frequency division multiplex signal demodulation means for demodulating the synthesized signal;
Decoding means for decoding the demodulated signal;
And a coefficient calculating means for obtaining a weight coefficient from signals received by the plurality of antennas ,
The variable delay means controls a speed at which the delay time changes, by a separately input control signal,
The digital broadcast receiver according to claim 1, wherein said coefficient calculating means obtains a covariance matrix of signals received from said plurality of antennas, and uses an eigenvector corresponding to a maximum eigenvalue of the matrix as a weight coefficient . A plurality of tuning means for tuning the same station;
The digital broadcast receiver according to claim 1, further comprising: a single local oscillation unit common to the plurality of channel selection units. The digital broadcast receiver according to claim 1, wherein the variable delay unit includes a dielectric element, and changes a dielectric constant by voltage control.

Images