JP5877368B2

JP5877368B2 - Demodulator

Info

Publication number: JP5877368B2
Application number: JP2011272640A
Authority: JP
Inventors: 真介植田; 吉木　和久; 和久吉木; 陽子谷利
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2011-12-13
Filing date: 2011-12-13
Publication date: 2016-03-08
Anticipated expiration: 2031-12-13
Also published as: JP2013126031A

Description

本発明は、周波数偏移キーイング(Frequency Shift Keying:FSK)方式で変調された信号を復調する復調器に関する。 The present invention relates to a demodulator that demodulates a signal modulated by frequency shift keying (FSK).

周波数偏移キーイング方式で変調された信号(以下、FSK変調信号と呼ぶ。)を復調する復調器としては、例えば、特許文献１に記載されているものがある。特許文献１記載の従来例は、検波回路の出力信号を高域遮断周波数の低いローパスフィルターにより濾波し、検波回路から出力される信号の平均電圧値を得る。この検波回路の出力信号の平均値を所定のタイミングでサンプル／ホールドすることによりデータ再生のための基準電圧を生成する。そして、ローパスフィルターの出力信号とサンプルホールド回路の出力電圧値を比較し、ローパスフィルターの出力信号がサンプルホールド回路の出力電圧値よりも高い場合に論理値１を出力し、低い場合には論理値０を出力する。 As a demodulator that demodulates a signal modulated by the frequency shift keying method (hereinafter referred to as an FSK modulation signal), for example, there is one described in Patent Document 1. In the conventional example described in Patent Document 1, the output signal of the detection circuit is filtered by a low-pass filter having a low high-frequency cutoff frequency, and an average voltage value of the signal output from the detection circuit is obtained. A reference voltage for data reproduction is generated by sampling / holding the average value of the output signal of the detection circuit at a predetermined timing. Then, the output signal of the low-pass filter is compared with the output voltage value of the sample and hold circuit. When the output signal of the low-pass filter is higher than the output voltage value of the sample and hold circuit, a logical value 1 is output. 0 is output.

特開平６−２２４９４９号公報JP-A-6-224949

しかしながら、特許文献１記載の従来例では、希望波以外の電波(以下、妨害波と呼ぶ。)を受信し、その妨害波に誤ってシンボル同期をとってしまった場合、希望波が到来しても当該希望波にシンボル同期をとるまでに多大な時間を要していた。 However, in the conventional example described in Patent Document 1, when a radio wave other than the desired wave (hereinafter referred to as an interfering wave) is received and symbol synchronization is erroneously taken for the interfering wave, the desired wave arrives. However, it took a long time to achieve symbol synchronization with the desired wave.

本発明は、上記課題に鑑みて為されたものであり、希望波にシンボル同期をとるまでの時間を短縮することを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to shorten the time required to achieve symbol synchronization with a desired wave.

本発明の復調器は、シンボル同期用の同期データを含み、周波数偏移キーイング方式で変調された変調信号を復調する復調器であって、前記変調信号が入力され、前記変調信号の周波数に対応した電圧値を有する検波信号を出力する検波部と、前記検波信号の電圧値を時間平均して平均電圧を生成する平均電圧生成部と、前記検波信号の電圧値を前記平均電圧と比較して前記検波信号に含まれる２値のデータを判定するデータ判定部と、前記検波信号又は前記平均電圧又は前記データ判定部から出力される前記データのうちの少なくとも何れか１つを監視し、前記変調信号に含まれている前記同期データを検出した場合に、前記平均電圧生成部に前記平均電圧を保持させる同期設定部と、前記平均電圧と前記検波信号の電圧値間の条件が所定のしきい値を満たした場合に、前記平均電圧生成部に対し前記平均電圧の保持を解除させる同期解除部とを備えることを特徴とする。 The demodulator of the present invention is a demodulator that includes synchronization data for symbol synchronization and demodulates a modulation signal modulated by a frequency shift keying method, and the modulation signal is input and corresponds to the frequency of the modulation signal A detection unit that outputs a detection signal having a detected voltage value, an average voltage generation unit that generates an average voltage by averaging the voltage value of the detection signal over time, and compares the voltage value of the detection signal with the average voltage. A data determination unit for determining binary data included in the detection signal; and at least one of the detection signal, the average voltage, or the data output from the data determination unit, and monitoring the modulation when it detects the synchronization data included in the signal, and the average voltage the average voltage causes maintain synchronization setting the generator unit, the condition of the voltage value of the average voltage and the detection signal is predetermined When it reaches the threshold, characterized in that with respect to the average voltage generating unit and a release cause synchronization releasing portion holding of the average voltage.

本発明の復調器は、シンボル同期用の同期データを含み、周波数偏移キーイング方式で変調された変調信号を復調する復調器であって、前記変調信号が入力され、前記変調信号の周波数に対応した電圧値を有する検波信号を出力する検波部と、前記検波信号の電圧値を２通りの時間でそれぞれ時間平均して２種類の平均電圧を生成する平均電圧生成部と、前記検波信号の電圧値を前記２種類の平均電圧のうちで時間の長い方の前記平均電圧と比較して前記検波信号に含まれる２値のデータを判定するデータ判定部と、前記検波信号又は前記平均電圧又は前記データ判定部から出力される前記データのうちの少なくとも何れか１つを監視し、前記変調信号に含まれている前記同期データを検出した場合に、前記平均電圧生成部に前記平均電圧を保持させる同期設定部と、前記２種類の平均電圧の差の条件が所定のしきい値を満たした場合に、前記平均電圧生成部に対し前記平均電圧の保持を解除させる同期解除部とを備えることを特徴とする。 The demodulator of the present invention is a demodulator that includes synchronization data for symbol synchronization and demodulates a modulation signal modulated by a frequency shift keying method, and the modulation signal is input and corresponds to the frequency of the modulation signal A detection unit that outputs a detection signal having the detected voltage value, an average voltage generation unit that generates two types of average voltages by averaging the voltage values of the detection signal over two different times, and the voltage of the detection signal A data determination unit that compares the value with the average voltage of the longer of the two types of average voltages and determines binary data included in the detection signal; and the detection signal or the average voltage or the when the at least any one of said data monitoring output from the data decision unit, detects said synchronization data included in the modulated signal, the average voltage to said average voltage generator Includes a synchronization setting unit causes lifting, if the conditions of the difference between the two average voltage satisfies a predetermined threshold value, and the average voltage release causes the synchronization releasing portion holding of generating said average voltage to unit It is characterized by that.

この復調器において、前記データ判定部から出力される前記データが前記同期データか否かを判別するデータ処理部を備え、前記同期解除部は、前記データ処理部の判別結果に基づき、前記データ判定部から前記同期データ以外のデータが出力されている場合、前記データ判定部から前記同期データが出力されている場合よりも、同期を解除する前記しきい値を高く設定していることが好ましい。 The demodulator includes a data processing unit that determines whether or not the data output from the data determination unit is the synchronization data, and the synchronization release unit determines the data determination based on a determination result of the data processing unit. When the data other than the synchronization data is output from the section, it is preferable that the threshold value for releasing the synchronization is set higher than when the synchronization data is output from the data determination section.

この復調器において、前記データ判定部から出力される前記データの長さをカウントするカウンタ部を備え、前記同期解除部は、前記カウンタ部でカウントされるデータ長が所定値に達すると、前記同期データ以外のデータが出力されている場合の前記しきい値を、前記同期データを検出した場合の前記しきい値に変更することが好ましい。 The demodulator includes a counter unit that counts the length of the data output from the data determination unit, and the synchronization release unit is configured to perform synchronization when the data length counted by the counter unit reaches a predetermined value. It is preferable to change the threshold value when data other than data is output to the threshold value when the synchronous data is detected.

この復調器において、前記条件は、前記検波信号の電圧値と前記平均電圧との差に基づく条件であることが好ましい。 In this demodulator, the condition is preferably a condition based on a difference between a voltage value of the detection signal and the average voltage.

この復調器において、前記条件は、前記検波信号の電圧値が連続して前記平均電圧を上回る時間又は下回る時間であることが好ましい。 In this demodulator, the condition is preferably a time when the voltage value of the detection signal continuously exceeds or falls below the average voltage.

この復調器において、前記条件は、前記検波信号の極値が連続して前記平均電圧を上回る回数又は下回る回数であることが好ましい。 In this demodulator, the condition is preferably the number of times that the extreme value of the detection signal continuously exceeds or falls below the average voltage.

本発明の復調器は、希望波にシンボル同期をとるまでの時間を短縮することができるという効果がある。 The demodulator of the present invention has an effect that the time until symbol synchronization with the desired wave can be shortened.

本発明に係る復調器の実施形態１を示すブロック図である。It is a block diagram which shows Embodiment 1 of the demodulator based on this invention. (ａ)，(ｂ)は検波信号と平均電圧の関係を示す波形図である。(a), (b) is a wave form diagram which shows the relationship between a detection signal and an average voltage. (ａ)，(ｂ)は検波信号と平均電圧の関係を示す波形図である。(a), (b) is a wave form diagram which shows the relationship between a detection signal and an average voltage. 本発明に係る復調器の実施形態２を示すブロック図である。It is a block diagram which shows Embodiment 2 of the demodulator based on this invention. 本発明に係る復調器の実施形態３を示すブロック図である。It is a block diagram which shows Embodiment 3 of the demodulator based on this invention.

(実施形態１)
本実施形態の復調器は、図１に示すようにシンボル同期用の同期データを含み、周波数偏移キーイング方式で変調された変調信号を復調するものであって、検波部１、平均電圧生成部２、同期設定部３、データ判定部４、同期解除部５などを備える。なお、シンボル同期用の同期データは、通常、「０」と「１」の相異なるシンボル(ビット)が交互に連続するデータ列からなる。また、シンボル同期用の同期データの後にフレーム同期用の同期データ(ユニークワード)が続き、フレーム同期用の同期データの後に送信データが続いており、シンボル同期、フレーム同期、送信データなどでフレームが構成されている。 (Embodiment 1)
The demodulator of the present embodiment demodulates a modulation signal that includes synchronization data for symbol synchronization as shown in FIG. 1 and is modulated by the frequency shift keying method, and includes a detector 1 and an average voltage generator. 2, a synchronization setting unit 3, a data determination unit 4, a synchronization release unit 5, and the like. Note that the synchronization data for symbol synchronization usually consists of a data string in which different symbols (bits) of “0” and “1” are alternately continued. Also, the synchronization data for frame synchronization (unique word) follows the synchronization data for symbol synchronization, the transmission data follows the synchronization data for frame synchronization, and the frame for symbol synchronization, frame synchronization, transmission data, etc. It is configured.

検波部１は、受信部10から出力される受信信号(変調信号)を周波数検波し、変調信号の周波数に対応した電圧値を有する検波信号を出力する(図２(ａ)における実線Ａ参照)。受信部10は、電波を受信するアンテナ11と、アンテナ11で受信される受信信号から変調信号の周波数帯域の信号成分をフィルタリングした後に増幅するなどの処理を行うフロントエンド12とを有する。 The detection unit 1 frequency-detects the reception signal (modulation signal) output from the reception unit 10 and outputs a detection signal having a voltage value corresponding to the frequency of the modulation signal (see a solid line A in FIG. 2A). . The receiving unit 10 includes an antenna 11 that receives radio waves and a front end 12 that performs processing such as filtering and amplifying a signal component in a frequency band of a modulated signal from a reception signal received by the antenna 11.

平均電圧生成部２は、検波信号の電圧値を時間平均して平均電圧を生成する(図２(ａ)における実線Ｂ参照)。データ判定部４は、検波信号の電圧値を平均電圧と比較して検波信号に含まれる２値のデータを判定する。同期設定部３は、検波信号又は平均電圧又はデータ判定部４から出力されるデータのうちの少なくとも何れか１つを監視し、変調信号に含まれているシンボル同期用の同期データを検出した場合、平均電圧生成部２に指示して平均電圧を保持する。例えば、同期設定部３は、データ判定部４から出力されるデータが「０」と「１」が交互且つ所定の頻度(通信のデータレート)でｎ回連続した場合に同期データを検出したと判断する。あるいは、検波信号の極大値(図２(ａ)における実線Ａの山の頂点)と、検波信号の極小値(図２(ａ)における実線Ａの谷の頂点)とが、平均電圧よりも高い状態と低い状態を交互且つ所定の頻度(通信のデータレート)でｎ回繰り返した場合に、同期設定部３が同期データを検出したと判断してもよい。若しくは、検波信号の増大と減少が交互且つ所定の頻度(通信のデータレート)でｎ回繰り返された場合に、同期設定部３が同期データを検出したと判断してもよい。 The average voltage generator 2 generates an average voltage by averaging the voltage value of the detection signal over time (see the solid line B in FIG. 2A). The data determination unit 4 determines the binary data contained in the detection signal by comparing the voltage value of the detection signal with the average voltage. When the synchronization setting unit 3 monitors at least one of the detection signal, the average voltage, or the data output from the data determination unit 4, and detects the synchronization data for symbol synchronization included in the modulation signal Instruct the average voltage generator 2 to hold the average voltage. For example, the synchronization setting unit 3 detects the synchronization data when the data output from the data determination unit 4 alternates “0” and “1” n times at a predetermined frequency (communication data rate). to decide. Alternatively, the maximum value of the detection signal (the peak of the peak of the solid line A in FIG. 2A) and the minimum value of the detection signal (the peak of the valley of the solid line A in FIG. 2A) are higher than the average voltage. When the state and the low state are alternately repeated n times at a predetermined frequency (communication data rate), it may be determined that the synchronization setting unit 3 has detected the synchronization data. Alternatively, when the increase and decrease of the detection signal are repeated alternately and n times at a predetermined frequency (communication data rate), it may be determined that the synchronization setting unit 3 has detected the synchronization data.

而して、同期設定部３がシンボル同期用の同期データを検出して平均電圧を保持すれば(シンボル同期をとれば)、シンボル同期に続いて検波信号に含まれているフレーム同期、さらに送信データをデータ判定部４で判定することができる。 Thus, if the synchronization setting unit 3 detects the synchronization data for symbol synchronization and holds the average voltage (if symbol synchronization is taken), the frame synchronization included in the detection signal following the symbol synchronization, and further transmission Data can be determined by the data determination unit 4.

ここで、受信部10で受信される妨害波によって同期設定部３が誤って平均電圧を保持してしまった場合(以下、「誤同期」と呼ぶ。)、誤同期中に受信部10で希望波が受信されても、希望波の検波信号の電圧値と平均電圧との差が大きければ、データ判定部４で正確にデータを判定することが困難になる。故に、受信部10で希望波を受信してもシンボル同期がとれずにデータの受信に失敗することになる。 Here, when the synchronization setting unit 3 erroneously holds the average voltage due to an interference wave received by the receiving unit 10 (hereinafter referred to as “mis-synchronization”), the receiving unit 10 desires during mis-synchronization. Even if a wave is received, if the difference between the voltage value of the detection signal of the desired wave and the average voltage is large, it is difficult for the data determination unit 4 to accurately determine the data. Therefore, even if the receiver 10 receives the desired wave, symbol synchronization is not achieved and data reception fails.

そこで本実施形態では、平均電圧と検波信号の電圧値間の条件が所定のしきい値を満たした場合、同期解除部５が平均電圧生成部２に指示して平均電圧の保持を解除する。その結果、平均電圧生成部２が再度平均電圧を算出するとともに同期設定部３が新たな平均電圧を設定するので、希望波にシンボル同期をとるまでの時間を短縮することができる。 Therefore, in the present embodiment, when the condition between the average voltage and the voltage value of the detection signal satisfies a predetermined threshold value, the synchronization release unit 5 instructs the average voltage generation unit 2 to release the holding of the average voltage. As a result, the average voltage generation unit 2 calculates the average voltage again and the synchronization setting unit 3 sets a new average voltage, so that the time until symbol synchronization with the desired wave can be shortened.

ところで、平均電圧と検波信号の電圧値間の条件とは、例えば、検波信号の電圧値と前記平均電圧との差に基づく条件であることが好ましい。つまり、図２(ａ)に示すように検波信号の電圧値の極値と平均電圧との差が所定範囲(±Vx)を超えた場合、同期解除部５が所定条件を満たした(希望波を受信した)と判断すればよい。このような条件を採用すれば、ランダムに発生するノイズへの誤同期に対して、希望波にシンボル同期をとるまでの時間を短縮することができる。 By the way, the condition between the average voltage and the voltage value of the detection signal is preferably a condition based on the difference between the voltage value of the detection signal and the average voltage, for example. That is, as shown in FIG. 2A, when the difference between the extreme value of the voltage value of the detection signal and the average voltage exceeds a predetermined range (± Vx), the synchronization release unit 5 satisfies the predetermined condition (the desired wave Is received). By adopting such a condition, it is possible to reduce the time required to achieve symbol synchronization with the desired wave against erroneous synchronization with randomly generated noise.

あるいは、平均電圧と検波信号の電圧値間の条件を、検波信号の電圧値が連続して平均電圧を上回る時間又は下回る時間としてもよい。例えば、図２(ｂ)に示すように平均電圧(実線Ｂ)よりも検波信号(実線Ａ)の電圧値の方が高くなる期間(時間)がしきい値Txを超えた場合、その検波信号が希望波であり、現在の同期が誤同期であるとみなすことができる。このような条件を採用すれば、他の電子機器から輻射されるクロック信号などへの誤同期に対して、希望波にシンボル同期をとるまでの時間を短縮することができる。 Alternatively, the condition between the average voltage and the voltage value of the detection signal may be a time when the voltage value of the detection signal continuously exceeds or falls below the average voltage. For example, when the period (time) in which the voltage value of the detection signal (solid line A) is higher than the average voltage (solid line B) exceeds the threshold value Tx as shown in FIG. Can be regarded as a desired wave and the current synchronization is a false synchronization. By adopting such a condition, it is possible to shorten the time until symbol synchronization with the desired wave with respect to erroneous synchronization with a clock signal or the like radiated from another electronic device.

または、平均電圧と検波信号の電圧値間の条件を、検波信号の極値が連続して平均電圧を上回る回数又は下回る回数としてもよい。例えば、図３(ａ)に示すように検波信号(実線Ａ)の極値が連続して平均電圧(実線Ｂ)を上回る回数がしきい値(９回)を超えた場合、その検波信号が希望波であり、現在の同期が誤同期であるとみなすことができる。 Alternatively, the condition between the average voltage and the voltage value of the detection signal may be the number of times that the extreme value of the detection signal continuously exceeds or falls below the average voltage. For example, as shown in FIG. 3A, when the number of times the extreme value of the detection signal (solid line A) continuously exceeds the average voltage (solid line B) exceeds a threshold value (9 times), the detection signal is It is a desired wave, and the current synchronization can be regarded as a false synchronization.

若しくは、平均電圧生成部２がサンプル数の異なる２種類の平均電圧(長時間平均電圧と短時間平均電圧)を生成するものである場合、平均電圧と検波信号の電圧値間の条件を、長時間平均電圧と短時間平均電圧の差に基づく条件としてよい。例えば、妨害波に誤同期しているときに妨害波と周波数(キャリア周波数)の異なる希望波が受信部10で受信されると、図３(ｂ)に示すように検波信号(実線Ａ)が急激に増大する。このとき、長時間平均電圧(実線Ｂ)は応答速度が遅いために緩やかに上昇し、短時間平均電圧(実線Ｃ)は応答速度が早いために素早く上昇するので、長時間平均電圧と短時間平均電圧との間に差が生じる。故に、長時間平均電圧と短時間平均電圧との差がしきい値Vyを超えた場合、同期解除部５が平均電圧の保持を解除して希望波に素早く同期させることができる。 Alternatively, when the average voltage generator 2 generates two types of average voltages (long-time average voltage and short-time average voltage) having different numbers of samples, the condition between the average voltage and the voltage value of the detection signal is long. The condition may be based on the difference between the time average voltage and the short time average voltage. For example, when a desired wave having a frequency (carrier frequency) different from that of the jamming wave is received by the receiving unit 10 while being erroneously synchronized with the jamming wave, a detection signal (solid line A) is generated as shown in FIG. Increases rapidly. At this time, the long-time average voltage (solid line B) rises gently because the response speed is slow, and the short-time average voltage (solid line C) rises quickly because the response speed is fast. There is a difference from the average voltage. Therefore, when the difference between the long-time average voltage and the short-time average voltage exceeds the threshold value Vy, the synchronization release unit 5 can release the holding of the average voltage and quickly synchronize with the desired wave.

(実施形態２)
本実施形態の復調器は、図４に示すようにデータ判定部４から出力されるデータが同期データか否かを判別するデータ処理部６を備える点が実施形態１と相違している。さらに同期解除部５は、データ処理部６の判別結果に基づき、データ判定部４から同期データが出力されている場合の条件に対して、データ判定部４から同期データ以外のデータ(ユニークワードや送信データ)が出力されている場合の条件を同期解除され難い条件に変更している。例えば、同期解除部５が同期を解除する(平均電圧の保持を止める)ための条件が、検波信号の電圧値の極値と平均電圧との差が所定範囲(平均電圧±Vx)を超えることであれば、同期データ以外のデータが出力されている場合、所定範囲を平均電圧±Vz(ただし、|Vz|>|Vx|)に拡大すればよい。 (Embodiment 2)
The demodulator of the present embodiment is different from the first embodiment in that the demodulator includes a data processing unit 6 that determines whether or not the data output from the data determination unit 4 is synchronous data, as shown in FIG. Further, based on the determination result of the data processing unit 6, the synchronization release unit 5 performs data other than the synchronization data from the data determination unit 4 (such as a unique word or The condition when (transmission data) is output has been changed to a condition that makes it difficult to release synchronization. For example, the condition for the synchronization release unit 5 to release the synchronization (stop the holding of the average voltage) is that the difference between the extreme value of the voltage value of the detection signal and the average voltage exceeds a predetermined range (average voltage ± Vx). Then, when data other than the synchronization data is output, the predetermined range may be expanded to the average voltage ± Vz (where | Vz |> | Vx |).

而して、送信データは同一のシンボル(ビット)が連続するデータ列(例えば、「０００００００」など)を含む場合があり、このようなデータ列が含まれていると、希望波を受信しているにも関わらず、同期解除部５が同期を解除してしまう可能性がある。これに対して本実施形態では、データ判定部４から同期データ以外のデータが出力されている場合、データ判定部４から同期データが出力されている場合よりも、同期を解除するしきい値を高く設定し、同期解除され難くしている。その結果、希望波にシンボル同期をとるまでの時間を短縮しつつ、希望波に対するシンボル同期が誤って解除されることを抑制することができる。 Thus, the transmission data may include a data string (for example, “0000000”) in which the same symbol (bit) is continuous, and if such a data string is included, the desired wave is received. In spite of this, there is a possibility that the synchronization cancellation unit 5 cancels the synchronization. On the other hand, in this embodiment, when data other than the synchronization data is output from the data determination unit 4, the threshold value for releasing the synchronization is set more than when the synchronization data is output from the data determination unit 4. Set it high, making it difficult to unlock. As a result, it is possible to prevent the symbol synchronization with respect to the desired wave from being erroneously canceled while shortening the time until symbol synchronization with the desired wave.

(実施形態３)
本実施形態の復調器は、図５に示すようにデータ判定部４から出力されるデータの長さをカウントするカウンタ部７を備える点が実施形態２と相違する。 (Embodiment 3)
The demodulator according to the present embodiment is different from the second embodiment in that the demodulator includes a counter unit 7 that counts the length of data output from the data determination unit 4 as shown in FIG.

カウンタ部７は、データ処理部６がデータ判定部４から同期データ以外のデータ(ユニークワードや送信データ)が出力されていると判断した時点からデータ長のカウントを開始し、データ長が所定値に達すると同期解除部５にフレーム終了信号を出力する。つまり、送信されるフレームの長さが固定されている場合、カウンタ部７でデータ長をカウントすることによってフレームの終了を検出することができる。 The counter unit 7 starts counting the data length when the data processing unit 6 determines that data (unique word or transmission data) other than the synchronization data is output from the data determination unit 4, and the data length is a predetermined value. When the value reaches, a frame end signal is output to the synchronization release unit 5. That is, when the length of the transmitted frame is fixed, the end of the frame can be detected by counting the data length by the counter unit 7.

一方、フレーム終了信号を受け取った同期解除部５は、同期データ以外のデータが出力されている場合のしきい値を、同期データを検出した場合のしきい値に変更する。その結果、次のフレームの受信に備えて再び同期解除されやすいしきい値に戻すことで希望波にシンボル同期をとるまでの時間を短縮することができる。 On the other hand, the synchronization release unit 5 that has received the frame end signal changes the threshold value when data other than the synchronization data is output to the threshold value when the synchronization data is detected. As a result, it is possible to shorten the time until the desired wave is symbol-synchronized by returning to the threshold value that is easy to cancel the synchronization again in preparation for the reception of the next frame.

１検波部
２平均電圧生成部
３同期設定部
４データ判定部
５同期解除部 DESCRIPTION OF SYMBOLS 1 Detection part 2 Average voltage generation part 3 Synchronization setting part 4 Data determination part 5 Synchronization cancellation | release part

Claims

A demodulator that includes synchronization data for symbol synchronization and that demodulates a modulation signal modulated by a frequency shift keying method, the detection signal having a voltage value corresponding to the frequency of the modulation signal, to which the modulation signal is input Included in the detection signal by comparing the voltage value of the detection signal with the average voltage, and an average voltage generation unit that generates an average voltage by averaging the voltage value of the detection signal over time. A data determination unit for determining value data; and at least one of the detection signal, the average voltage, or the data output from the data determination unit, and is included in the modulation signal when detecting the synchronization data, and the average voltage the average voltage causes maintain synchronization setting the generator unit, the condition of the voltage value of the average voltage and the detection signal satisfies a predetermined threshold value Case, the demodulator, characterized in that with respect to the average voltage generating unit and a release cause synchronization releasing portion holding of the average voltage.

A demodulator that includes synchronization data for symbol synchronization and that demodulates a modulation signal modulated by a frequency shift keying method, the detection signal having a voltage value corresponding to the frequency of the modulation signal, to which the modulation signal is input A detection unit that outputs a voltage, an average voltage generation unit that generates two types of average voltages by averaging the voltage values of the detection signal in two different times, and an average of the two types of voltage values of the detection signal A data determination unit that determines binary data included in the detection signal in comparison with the longer average voltage among the voltages, and is output from the detection signal, the average voltage, or the data determination unit monitors at least any one of the data, when it detects the synchronization data contained in the modulated signal, the average voltage causes maintain synchronization set to the average voltage generator If, when said condition the difference between the two average voltage satisfies a predetermined threshold, characterized in that it comprises a said average voltage generator release causes the synchronization releasing portion holding said average voltage to Demodulator.

A data processing unit for determining whether or not the data output from the data determination unit is the synchronization data, and the synchronization release unit receives the synchronization data from the data determination unit based on a determination result of the data processing unit; The threshold value for releasing the synchronization is set higher when the data other than the above is output, compared with the case where the synchronization data is output from the data determination unit. 2. The demodulator according to 2.

A counter unit that counts the length of the data output from the data determination unit; and when the data length counted by the counter unit reaches a predetermined value, data other than the synchronization data 4. The demodulator according to claim 3, wherein the threshold value when output is changed to the threshold value when the synchronization data is detected.

The demodulator according to claim 1, wherein the condition is a condition based on a difference between a voltage value of the detection signal and the average voltage.

The demodulator according to claim 1, wherein the condition is a time when the voltage value of the detection signal continuously exceeds or falls below the average voltage.

The demodulator according to claim 1, wherein the condition is the number of times that the extreme value of the detection signal continuously exceeds or falls below the average voltage.