JP2006254273A - Receiving apparatus - Google Patents
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本発明は、異なる変調方式によりそれぞれ変調された変調データが時間軸多重された伝送フレームが周期的に伝送されるデジタル伝送システムに好適な受信装置に関するものである。
また、本発明は、デジタルケーブルテレビのような大容量伝送システムに好適な受信装置に関するものである。
The present invention relates to a receiving apparatus suitable for a digital transmission system in which transmission frames in which modulated data modulated by different modulation schemes are time-axis multiplexed are periodically transmitted.
The present invention also relates to a receiving apparatus suitable for a large-capacity transmission system such as a digital cable television.
大容量伝送システムの実用化に伴い、１つのフレーム中に異なる変調方式によりそれぞれ変調された複数の変調データを時間軸多重して伝送するデジタル伝送システムが開発されている。このデジタル伝送システムに用いられる受信装置において、受信した信号について良好な復調を行うためには、正確な同期検出を行うことが重要である。従来のフレーム同期方式においては、フレーム中に同期パターンとしてユニークワードが付加され、受信した信号中の同期パターンとユニークワードとの間の相関を求めることによりフレーム同期が検出されていた（例えば、特許文献１参照）。 Along with the practical application of a large-capacity transmission system, a digital transmission system has been developed in which a plurality of modulated data modulated by different modulation methods in one frame are time-axis multiplexed and transmitted. In order to perform good demodulation on a received signal in a receiving device used in this digital transmission system, it is important to perform accurate synchronization detection. In a conventional frame synchronization method, a unique word is added as a synchronization pattern in a frame, and frame synchronization is detected by obtaining a correlation between the synchronization pattern and the unique word in the received signal (for example, patents) Reference 1).
また、変調されたデータの変調方式を識別する方法として、変調波のベースバンド信号の特徴量、例えば連続するシンボル間の位相差分値の分散とシンボルの瞬時振幅値の標準偏差との組み合わせによる特徴をメモリに記憶し、受信信号の特徴をメモリに記憶した特徴と比較することにより変調方式を識別する方法が提案されている（例えば、特許文献２参照）。 Also, as a method for identifying the modulation method of the modulated data, the characteristic amount of the baseband signal of the modulated wave, for example, the feature by the combination of the variance of the phase difference value between consecutive symbols and the standard deviation of the instantaneous amplitude value of the symbol Has been proposed in which the modulation scheme is identified by comparing the characteristics of the received signal with the characteristics stored in the memory (for example, see Patent Document 2).
フレームの先頭にユニークワードが同期パターンとして付加されているフレーム信号を伝送するシステムの受信機では、ユニークワードとの相関検出によりフレーム同期を検出する。そのため、ユニークワードが挿入されている区間内に情報を多重することができなかった。一方、同期パターンが挿入されている区間内に情報を多重することができれば、情報伝送効率を一層向上させることができる。そのためには、複数の変調方式を区別してフレーム周期を識別するための手段が必要である。
また、受信信号をベースバンド帯の信号に変換し、位相差分値の分散と振幅値の標準偏差とを２次元的に記憶したメモリを用いて変調方式を識別する方法では、受信装置に比較的大容量のメモリを設置する必要があり、構造的に複雑化する欠点がある。
In a receiver of a system that transmits a frame signal in which a unique word is added as a synchronization pattern to the head of a frame, frame synchronization is detected by detecting a correlation with the unique word. For this reason, information cannot be multiplexed within the section in which the unique word is inserted. On the other hand, if information can be multiplexed within a section in which a synchronization pattern is inserted, information transmission efficiency can be further improved. For this purpose, a means for distinguishing a plurality of modulation schemes and identifying a frame period is necessary.
Further, in a method of converting a received signal into a baseband signal and identifying a modulation method using a memory in which the dispersion of the phase difference value and the standard deviation of the amplitude value are two-dimensionally stored, the receiving apparatus is relatively It is necessary to install a large-capacity memory, and there is a drawback that the structure becomes complicated.
本発明の目的は、従来同期パターンが挿入されていた区間にも情報を多重することができ、情報伝送効率が一層向上したデジタル伝送システムに用いられる受信装置を提供することにある。
さらに、本発明の別の目的は、比較的大容量のメモリを用いることなくフレーム同期を行うことができる受信装置を提供することにある。
さらに、本発明の別の目的は、デジタルケーブルテレビのようなな大容量伝送システムに好適な受信装置を提供することにある。
An object of the present invention is to provide a receiver used in a digital transmission system that can multiplex information even in a section in which a conventional synchronization pattern has been inserted, and further improve information transmission efficiency.
Furthermore, another object of the present invention is to provide a receiving apparatus capable of performing frame synchronization without using a relatively large capacity memory.
Furthermore, another object of the present invention is to provide a receiving apparatus suitable for a large-capacity transmission system such as a digital cable television.
本発明による受信装置は、シンボルの振幅が一定の位相変調方式により変調された変調データと、前記位相変調方式とは異なる別の変調方式により変調された変調データとが時間軸多重されたフレームが周期的に伝送されるデジタル伝送システムに用いられる受信装置において、
前記位相変調方式と同一の変調方式の振幅が一定のシンボル列を発生する手段と、当該シンボル列のシンボルの振幅と受信信号のシンボルの振幅との差分の絶対値を検出する差分検出手段とを具え、前記差分検出手段からの出力に基づいて前記位相変調方式により変調された変調データの区間と前記別の変調方式により変調された変調データの区間とを識別することを特徴とする。
The receiving apparatus according to the present invention has a frame in which modulation data modulated by a phase modulation method with a constant symbol amplitude and modulation data modulated by another modulation method different from the phase modulation method are time-axis multiplexed. In a receiver used in a digital transmission system that is periodically transmitted,
Means for generating a symbol string having a constant amplitude of the same modulation method as the phase modulation method, and difference detecting means for detecting an absolute value of a difference between the amplitude of the symbol of the symbol string and the amplitude of the symbol of the received signal In addition, a section of modulation data modulated by the phase modulation scheme and a section of modulation data modulated by the other modulation scheme are identified based on an output from the difference detection means.
Ｎ相の位相変調信号の受信信号は、周波数誤差を含んでいる場合でもシンボルは2次元平面上で同心円状のコンスタレーションとなる。本発明では、検出すべき位相変調方式のシンボルの理想的な振幅のシンボル列を発生する手段を有し、当該シンボル列発生手段から生成したシンボル列のシンボルの振幅と受信信号の振幅との差の絶対値を算出する。受信信号が理想的な場合には、位相変調されたシンボル列の区間について差の絶対値は零になる。一方、振幅が変化する変調方式のシンボル列については、受信信号のシンボルの振幅とシンボル列発生手段からのシンボルの振幅との差の絶対値は絶対値は零とはならない。従って、シンボル列発生手段からのシンボルの振幅と受信信号のシンボルの振幅との差分の絶対値を算出し、その結果を利用することにより、位相変調方式により変調された変調データの区間と別の変調方式により変調された変調データ区間とを識別することができる。この結果、位相変調方式により変調された区間をフレーム同期検出及び情報伝送の両方の目的に利用することができる。よって、フレームに同期パターンを形成することなく、互いに異なる変調方式により変調された変調データを識別できるので、従来同期パターンが挿入されていたフレーム区間内にも変調データを挿入することができる。 Even when the received signal of the N-phase modulated signal includes a frequency error, the symbols are concentric constellations on a two-dimensional plane. In the present invention, there is provided means for generating a symbol string having an ideal amplitude of the symbol of the phase modulation system to be detected, and the difference between the amplitude of the symbol of the symbol string generated from the symbol string generating means and the amplitude of the received signal The absolute value of is calculated. When the received signal is ideal, the absolute value of the difference is zero for the section of the phase-modulated symbol string. On the other hand, for a modulation type symbol string whose amplitude varies, the absolute value of the difference between the amplitude of the symbol of the received signal and the amplitude of the symbol from the symbol string generating means is not zero. Therefore, by calculating the absolute value of the difference between the amplitude of the symbol from the symbol sequence generating means and the amplitude of the symbol of the received signal, and using the result, it is possible to obtain a different value from that of the modulation data modulated by the phase modulation method. It is possible to distinguish the modulation data section modulated by the modulation method. As a result, the section modulated by the phase modulation method can be used for both purposes of frame synchronization detection and information transmission. Therefore, since modulation data modulated by different modulation schemes can be identified without forming a synchronization pattern in the frame, it is possible to insert modulation data in a frame section in which a conventional synchronization pattern has been inserted.
本発明による受信装置は、シンボルの振幅が一定の位相変調方式により変調された変調データと、前記位相変調方式とは異なる別の変調方式により変調された変調データとが時間軸多重されているフレームが周期的に伝送されるデジタル伝送システムに用いられる受信装置において、
前記シンボルの振幅が一定の位相変調方式と同一の変調方式の振幅が一定のシンボル列を発生する手段と、当該シンボル列のシンボルの振幅と受信信号のシンボルの振幅との差分の絶対値を検出する差分検出手段と、前記差分検出手段からの出力について、所定のシンボル数にわたって移動平均を求める移動平均算出手段と、移動平均算出手段からの出力の最小値を検出する最小値検出手段とを具え、
前記算出された移動平均の最小値からフレーム同期を検出することを特徴とする。
A receiving apparatus according to the present invention is a frame in which modulation data modulated by a phase modulation method with a constant symbol amplitude and modulation data modulated by another modulation method different from the phase modulation method are time-axis multiplexed. In a receiver used in a digital transmission system in which is periodically transmitted,
Means for generating a symbol string having a constant amplitude of the same modulation system as the phase modulation system having a constant symbol amplitude, and detecting an absolute value of a difference between the symbol amplitude of the symbol string and the symbol amplitude of the received signal Difference detecting means, a moving average calculating means for obtaining a moving average over a predetermined number of symbols for the output from the difference detecting means, and a minimum value detecting means for detecting a minimum value of the output from the moving average calculating means. ,
Frame synchronization is detected from the calculated minimum value of the moving average.
受信信号のシンボルの振幅とシンボル列発生手段から発生したシンボルの振幅との差分の絶対値について、シンボルの振幅が一定の位相変調方式の区間のシンボル数だけ移動平均を加算することにより、移動平均の最小値が位相変調方式で変調された変調データの区間と別の変調方式の変調データの区間との境界を表すことになる。従って、移動平均の最小値を検出することにより、フレーム同期が検出されるので、変調波のベースバンド信号の特徴量を示す2次元テーブルのメモリを参照することなく、簡単な回路でフレーム同期を検出することができる。 For the absolute value of the difference between the amplitude of the symbol of the received signal and the amplitude of the symbol generated from the symbol string generation means, the moving average is added by adding the moving average by the number of symbols in the section of the phase modulation method in which the symbol amplitude is constant. Is the boundary between the modulation data section modulated by the phase modulation method and the modulation data section of another modulation method. Therefore, since frame synchronization is detected by detecting the minimum value of the moving average, frame synchronization can be performed with a simple circuit without referring to the memory of the two-dimensional table indicating the feature quantity of the baseband signal of the modulated wave. Can be detected.
本発明による別の受信装置は、所定数のシンボルを含み、各シンボルの振幅が一定の位相変調方式により変調された第１の変調データと、所定数のシンボルを含み、前記位相変調方式とは異なる別の変調方式により変調された第２の変調データとが時間軸多重されているフレームが周期的に伝送されるデジタル伝送システムに用いられる受信装置において、
受信信号の連続するシンボルの振幅の絶対値を算出する第1の絶対値算出手段と、前記位相変調方式と同一の変調方式の振幅が一定のシンボル列を発生するシンボル列発生手段と、前記シンボル列発生手段から順次出力されるシンボルの振幅の絶対値を算出する第２の絶対値算出手段と、前記第１の絶対値算出手段からの出力と第２の絶対値算出手段からの出力とをシンボル毎に減算して、受信信号のシンボルの振幅とシンボル列発生手段から出力されたシンボルの振幅との差分の絶対値を検出する差分検出手段と、差分検出手段からの出力を前記第１の変調データのシンボル数だけ順次加算する移動平均算出手段と、移動平均算出手段からの出力信号について最小値を検出する最小値検出手段とを具え、前記最小値検出手段からの出力に基づいてフレーム同期を検出することを特徴とする。
Another receiving apparatus according to the present invention includes a first modulation data that includes a predetermined number of symbols, the amplitude of each symbol being modulated by a constant phase modulation scheme, and a predetermined number of symbols. In a receiver used in a digital transmission system in which a frame in which time-division multiplexed second modulation data modulated by another different modulation scheme is periodically transmitted,
First absolute value calculating means for calculating the absolute value of the amplitude of consecutive symbols of the received signal, symbol string generating means for generating a symbol string having a constant amplitude in the same modulation scheme as the phase modulation scheme, and the symbol A second absolute value calculating means for calculating the absolute value of the amplitude of the symbols sequentially output from the column generating means; an output from the first absolute value calculating means; and an output from the second absolute value calculating means. Subtracting for each symbol, a difference detecting means for detecting the absolute value of the difference between the amplitude of the symbol of the received signal and the amplitude of the symbol output from the symbol string generating means, and the output from the difference detecting means as the first A moving average calculating means for sequentially adding the number of symbols of the modulation data; and a minimum value detecting means for detecting a minimum value of the output signal from the moving average calculating means, and based on the output from the minimum value detecting means. And frame synchronization is detected.
本発明による受信装置の好適実施例は、最小値検出手段からの出力を用いて順次受信するフレームの伝送周期を決定すると共に、前記第１の変調データの区間と第２の変調データの区間とを識別することを特徴とする。 In a preferred embodiment of the receiving apparatus according to the present invention, the transmission period of frames to be sequentially received is determined using the output from the minimum value detecting means, and the first modulation data interval and the second modulation data interval are determined. It is characterized by identifying.
本発明による受信装置の別の好適実施例は、シンボルの振幅が一定の位相変調方式としてBPSK方式を用い、前記別の変調方式として直交振幅変調方式を用いることを特徴とする。 Another preferred embodiment of the receiving apparatus according to the present invention is characterized in that the BPSK method is used as the phase modulation method with a constant symbol amplitude, and the quadrature amplitude modulation method is used as the other modulation method.
本発明では、受信信号の各シンボルの振幅とシンボルの振幅が一定の位相変調方式により発生したシンボル列のシンボルの振幅との差分の絶対値を算出し、その結果に基づいてフレーム同期を検出すると共に変調データの区間を識別しているので、位相変調方式により変調された変調データの区間をフレーム同期検出及びデータ伝送の両方に用いることができる。この結果、特別な同期パターンを用いることなくフレーム同期を検出することができる。よって、従来同期パターンが挿入されていたフレーム区間にも変調データを挿入することができ、情報伝送効率を一層高めることが可能になると共に簡単な回路構成でフレーム同期の検出及び変調データの各区間を識別することができる。例えば、デジタル放送の分配伝送システムの応用としては、本発明の伝送フレーム内に複数のMPEG-2 TS信号を多重するためのフレームを構成することを想定する。4096QAM区間に複数のMPEG-2 TSパケットを配置する場合、各TSパケットとTSid(TS識別番号)との関係をフレームのヘッダに示す必要が生ずる。そこで、このヘッダ情報をBPSK区間に多重することで効率よく複数のMPEG-2 TSの多重を行うことが可能になる。この結果、デジタルケーブルテレビのような大容量伝送システムに好適な受信装置を実現することができる。 In the present invention, the absolute value of the difference between the amplitude of each symbol of the received signal and the amplitude of the symbol in the symbol string generated by the phase modulation method with a constant symbol amplitude is calculated, and frame synchronization is detected based on the result. In addition, since the section of the modulated data is identified, the section of the modulated data modulated by the phase modulation method can be used for both frame synchronization detection and data transmission. As a result, frame synchronization can be detected without using a special synchronization pattern. Therefore, modulation data can be inserted into a frame section in which a conventional synchronization pattern has been inserted, so that information transmission efficiency can be further improved, and frame synchronization detection and each section of modulation data can be performed with a simple circuit configuration. Can be identified. For example, as an application of a distribution transmission system for digital broadcasting, it is assumed that a frame for multiplexing a plurality of MPEG-2 TS signals is configured in a transmission frame of the present invention. When a plurality of MPEG-2 TS packets are arranged in a 4096QAM section, it is necessary to indicate the relationship between each TS packet and TSid (TS identification number) in the frame header. Therefore, it is possible to multiplex a plurality of MPEG-2 TS efficiently by multiplexing this header information in the BPSK section. As a result, a receiving apparatus suitable for a large-capacity transmission system such as a digital cable television can be realized.
図１は、本発明が適用されるデジタル伝送システムにおける伝送フレームの一例を示す線図である。本例の伝送フレームは、デジタルケーブルテレビの大容量伝送装置から各ユーザの受信装置に周期的に送信される伝送フレームとすることができる。各伝送フレームは、シンボルの振幅が一定の二相位相変調方式(BPSK）により変調された区間とシンボルの振幅が時間ともに変化する直交振幅変調方式(4096QAM)により変調された区間とを含み、BPSKの区間及び4096QAMの区間は共にデータ変調されているものとする。一例として、各フレームは２１４ 個のシンボルを含み、BPSKには1024個のシンボルを割り当て、4096QAMには15360個のシンボルを割り当てる。これらのBPSKの区間及び4096QAMの区間のシンボル数は受信装置側において既知のものとする。本発明をデジタル放送の分配伝送システムに適用する場合、伝送フレーム中に複数のMPEG-2 TSパケットを配置する場合、各TSパケットとTS識別番号との関係を示すヘッダ情報をBPSK区間に多重し、MPEG-2 TSパケットを4096QAM区間に多重することができる。 FIG. 1 is a diagram showing an example of a transmission frame in a digital transmission system to which the present invention is applied. The transmission frame of this example can be a transmission frame periodically transmitted from the large-capacity transmission device of the digital cable television to the receiving device of each user. Each transmission frame includes a section modulated by a two-phase phase modulation method (BPSK) in which the symbol amplitude is constant and a section modulated by a quadrature amplitude modulation method (4096QAM) in which the symbol amplitude changes with time. It is assumed that both of the interval of 4 and the interval of 4096QAM are data modulated. As an example, each frame includes 2 14 symbols, 1024 symbols are assigned to BPSK, and 15360 symbols are assigned to 4096QAM. The number of symbols in these BPSK sections and 4096QAM sections is assumed to be known on the receiving apparatus side. When the present invention is applied to a distribution transmission system for digital broadcasting, when a plurality of MPEG-2 TS packets are arranged in a transmission frame, header information indicating the relationship between each TS packet and a TS identification number is multiplexed in a BPSK section. MPEG-2 TS packets can be multiplexed in a 4096QAM section.
上記伝送フレームは、従来同期パターンが挿入されていた区間もデータ変調されているため、大容量伝送装置から周期的に送信されてくるフレームを復調するためには、フレーム同期を検出すると共に各変調方式によりそれぞれ変調された区間を識別する必要がある。図2は、フレーム同期検出を行うと共に変調区間を識別するフレーム同期回路の一例を示す線図である。受信信号（r(nT)）は絶対値算出回路１に入力し、順次受信された受信信号の連続する各シンボルの振幅の絶対値が順次算出される。算出された受信信号の各シンボルの振幅の絶対値は減算器２に順次供給する。減算器２の他方の入力部にはシンボル列発生回路３を接続する。このシンボル列発生回路３にはシンボルレート情報が入力し、BPSK方式により変調され振幅が一定の連続するシンボル列を発生し、各シンボルの振幅の絶対値を順次出力する。従って、減算器２から、受信信号の連続する各シンボルの振幅の絶対値とBPSK方式のシンボル列の各シンボルの振幅の絶対値との差（ｃ’(nT)）がシンボル毎に順次出力される。 Since the transmission frame is also data-modulated in the section where the conventional synchronization pattern has been inserted, in order to demodulate the frame periodically transmitted from the large-capacity transmission device, the frame synchronization is detected and each modulation is performed. It is necessary to identify the sections modulated by the method. FIG. 2 is a diagram showing an example of a frame synchronization circuit that performs frame synchronization detection and identifies a modulation interval. The received signal (r (nT)) is input to the absolute value calculation circuit 1, and the absolute value of the amplitude of each successive symbol of the received signal that is sequentially received is sequentially calculated. The calculated absolute value of the amplitude of each symbol of the received signal is sequentially supplied to the subtracter 2. A symbol string generation circuit 3 is connected to the other input section of the subtracter 2. Symbol rate generation circuit 3 receives symbol rate information, generates a continuous symbol string modulated by the BPSK method and having a constant amplitude, and sequentially outputs the absolute value of the amplitude of each symbol. Accordingly, the difference (c ′ (nT)) between the absolute value of the amplitude of each successive symbol of the received signal and the absolute value of the amplitude of each symbol in the BPSK symbol sequence is sequentially output from the subtracter 2 for each symbol. The
減算器２からの出力を移動平均算出回路４に供給する。移動平均算出回路４では、受信信号中の連続する各シンボルの振幅の絶対値とBPSKのシンボル列の連続する各シンボルの振幅の絶対値との差分を順次加算し、1つのフレームのBPSK区間中に含まれるシンボル数（本例では、Tr＝1024個）の和の加算値を順次算出する。すなわち、連続する各シンボルの絶対値の差分値を再先に加算された差分値と置換するように順次加算して合計１０２４個の差分値の和を順次出力する。 The output from the subtracter 2 is supplied to the moving average calculation circuit 4. In the moving average calculation circuit 4, the difference between the absolute value of the amplitude of each successive symbol in the received signal and the absolute value of the amplitude of each successive symbol in the BPSK symbol sequence is sequentially added, and the BPSK interval of one frame Are sequentially calculated as the sum of the number of symbols (Tr = 1024 in this example). That is, the difference value of the absolute value of each successive symbol is added sequentially so as to replace the difference value added earlier, and the sum of a total of 1024 difference values is sequentially output.
図3は、移動平均算出回路４からの出力信号を示す線図である。図３において、横軸は連続するシンボル数を示し、縦軸は移動平均算出回路の出力値（相対値）を示す。順次受信される各フレームは、先頭から、振幅が一定の１０２４個のシンボル列（BPSK区間）が受信され、続いて振幅の変化する（２１４ −１０２４）個のシンボル列（4096QAM区間）が受信される。従って、受信信号中の4096QAM区間のシンボルと参照用のBPSKのシンボル列との間の差分の絶対値が出力されるときは、移動平均算出回路４からの出力信号はあるレベルの値となる。一方、受信フレーム中のBPSK区間のシンボルとの差分値が出力されると、移動平均算出回路からの出力信号レベルは徐々に小さくなり、連続するBPSKシンボルの数が1024個の時、最小値が出力される。従って、移動平均算出回路４の後段に最小値検出回路５を設け、移動平均算出回路からの出力信号の最小値を検出することにより変調方式の異なるBPSK区間と4096QAM区間との間の境界並びにフレーム同期が検出される。 FIG. 3 is a diagram showing an output signal from the moving average calculation circuit 4. In FIG. 3, the horizontal axis indicates the number of consecutive symbols, and the vertical axis indicates the output value (relative value) of the moving average calculation circuit. Each frame is sequentially received from the head, the amplitude is received a constant 1024 symbols columns (BPSK section) is followed by a change in the amplitude (2 14 -1024) symbol sequence (4096QAM section) is received Is done. Therefore, when the absolute value of the difference between the symbol of the 4096QAM section in the received signal and the reference BPSK symbol string is output, the output signal from the moving average calculation circuit 4 has a value of a certain level. On the other hand, when the difference value from the BPSK symbol in the received frame is output, the output signal level from the moving average calculation circuit gradually decreases, and when the number of consecutive BPSK symbols is 1024, the minimum value is Is output. Therefore, the minimum value detection circuit 5 is provided in the subsequent stage of the moving average calculation circuit 4, and the boundary between the BPSK section and the 4096QAM section having different modulation schemes and the frame are detected by detecting the minimum value of the output signal from the moving average calculation circuit. Synchronization is detected.
受信装置側においては、検出されたフレーム同期に基づいてフレームの伝送周波数及び伝送周期を求めることができる。さらに、受信装置において、フレーム全体のシンボル数及び各変調区間のシンボル数が既知であるから、各フレームのBPSKの変調区間と4096QAMの変調区間とを識別することができる。この結果、従来の伝送フレームにおいて同期パターンが挿入されていた区間に変調データを挿入しても、受信装置側において当該区間の変調データを復調することができると共にフレーム同期も検出することができ、情報伝送効率を一層高めることが可能になる。さらに、変調方式を識別する手段も不要になる。 On the receiving device side, the transmission frequency and transmission period of the frame can be obtained based on the detected frame synchronization. Furthermore, since the number of symbols in the entire frame and the number of symbols in each modulation section are known in the receiving apparatus, the BPSK modulation section and the 4096QAM modulation section in each frame can be identified. As a result, even if modulation data is inserted in a section where a synchronization pattern has been inserted in a conventional transmission frame, the modulation data in the section can be demodulated on the receiving apparatus side, and frame synchronization can also be detected. Information transmission efficiency can be further increased. Furthermore, a means for identifying the modulation method is not required.
本発明は上述した実施例だけに限定されず種々の変形や変更が可能である。例えば、上述した実施例では、BPSK方式により変調された変調データと4096QAM方式により変調された変調データとが時間軸多重されたフレームについて説明したが、BPSKと４PSK又は8PSKによる変調データと直交振幅変調による変調データとを時間軸多重したフレームについても適用することができる。この場合、BPSK検出と並列して４PSK検出又は８PSK検出を行い、それぞれ移動平均を求め、移動平均の最小値を検出することにより、変調方式の異なるデータ区間の境界を検出することができる。 The present invention is not limited to the above-described embodiments, and various modifications and changes can be made. For example, in the above-described embodiment, the frame in which the modulation data modulated by the BPSK method and the modulation data modulated by the 4096QAM method are time-axis multiplexed has been described. The present invention can also be applied to a frame obtained by time-multiplexing modulated data obtained by the above method. In this case, 4PSK detection or 8PSK detection is performed in parallel with BPSK detection, a moving average is obtained, and a minimum value of the moving average is detected, so that the boundary between data sections having different modulation schemes can be detected.
１ 絶対値算出回路
２ 減算器
３ シンボル列発生回路
４ 移動平均算出回路
５ 最小値検出回路
DESCRIPTION OF SYMBOLS 1 Absolute value calculation circuit 2 Subtractor 3 Symbol sequence generation circuit 4 Moving average calculation circuit 5 Minimum value detection circuit
Claims (5)
前記位相変調方式と同一の変調方式の振幅が一定のシンボル列を発生する手段と、当該シンボル列のシンボルの振幅と受信信号のシンボルの振幅との差分の絶対値を算出する差分検出手段とを具え、前記差分検出手段からの出力に基づいて前記位相変調方式により変調された変調データの区間と前記別の変調方式により変調された変調データの区間とを識別することを特徴とする受信装置。 Digital in which a frame in which modulation data modulated by a phase modulation scheme with a constant symbol amplitude and modulation data modulated by another modulation scheme different from the phase modulation scheme is time-axis multiplexed is periodically transmitted In a receiving device used in a transmission system,
Means for generating a symbol string having a constant amplitude of the same modulation method as the phase modulation method, and difference detecting means for calculating an absolute value of a difference between the amplitude of the symbol of the symbol string and the amplitude of the symbol of the received signal. And a receiving apparatus for identifying a section of modulation data modulated by the phase modulation scheme and a section of modulation data modulated by the other modulation scheme based on an output from the difference detection means.
前記位相変調方式と同一の変調方式の振幅が一定のシンボル列を発生する手段と、当該シンボル列のシンボルの振幅と受信信号のシンボルの振幅との差分の絶対値を算出する差分検出手段と、前記差分検出手段からの出力について、所定のシンボル数にわたって移動平均を求める移動平均算出手段と、移動平均算出手段からの出力の最小値を検出する最小値検出手段とを具え、
前記算出された移動平均の最小値からフレーム同期を検出することを特徴とする受信装置。 A frame in which modulation data modulated by a phase modulation scheme with a constant symbol amplitude and modulation data modulated by a modulation scheme different from the phase modulation scheme is time-axis multiplexed is periodically transmitted. In a receiver used in a digital transmission system,
Means for generating a symbol string having a constant amplitude of the same modulation method as the phase modulation method; difference detecting means for calculating an absolute value of a difference between the amplitude of the symbol of the symbol string and the amplitude of the symbol of the received signal; For the output from the difference detection means, comprising a moving average calculation means for obtaining a moving average over a predetermined number of symbols, and a minimum value detection means for detecting a minimum value of the output from the moving average calculation means,
A receiving apparatus, wherein frame synchronization is detected from the calculated minimum value of the moving average.
受信信号のシンボルの振幅の絶対値を順次算出する第1の絶対値算出手段と、前記位相変調方式と同一の変調方式の振幅が一定のシンボル列を発生するシンボル列発生手段と、前記シンボル列発生手段から順次出力されるシンボルの振幅の絶対値を算出する第２の絶対値算出手段と、前記第１の絶対値算出手段からの出力と第２の絶対値算出手段からの出力とをシンボル毎に減算して、受信信号のシンボルの振幅とシンボル列発生手段から出力されたシンボルの振幅との差分の絶対値を検出する差分検出手段と、差分検出手段からの出力を前記第１の変調データのシンボル数だけ順次加算する移動平均算出手段と、移動平均算出手段からの出力信号について最小値を検出する最小値検出手段とを具え、前記最小値検出手段からの出力に基づいてフレーム同期を検出することを特徴とする受信装置。 First modulation data including a predetermined number of symbols and modulated by a phase modulation method in which the amplitude of each symbol is constant, and a predetermined number of symbols and modulated by another modulation method different from the phase modulation method In a receiver used in a digital transmission system in which a frame in which the second modulation data is time-axis multiplexed is periodically transmitted,
A first absolute value calculating means for sequentially calculating an absolute value of an amplitude of a symbol of a received signal; a symbol string generating means for generating a symbol string having a constant amplitude in the same modulation scheme as the phase modulation scheme; and the symbol string The second absolute value calculating means for calculating the absolute value of the amplitude of the symbols sequentially output from the generating means, the output from the first absolute value calculating means and the output from the second absolute value calculating means as symbols Subtracting each time to detect the absolute value of the difference between the amplitude of the symbol of the received signal and the amplitude of the symbol output from the symbol string generating means, and the output from the difference detecting means to the first modulation A moving average calculating means for sequentially adding the number of data symbols; and a minimum value detecting means for detecting a minimum value of an output signal from the moving average calculating means, and based on an output from the minimum value detecting means. A receiving apparatus for detecting frame synchronization.
5. The receiving apparatus according to claim 1, wherein a BPSK system is used as a phase modulation system in which the amplitude of the symbol is constant, and a quadrature amplitude modulation system is used as the other modulation system. Receiving device.
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