JP5733107B2 - FSK signal detection apparatus, receiver, and FSK signal detection method - Google Patents

FSK signal detection apparatus, receiver, and FSK signal detection method Download PDF

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JP5733107B2
JP5733107B2 JP2011184051A JP2011184051A JP5733107B2 JP 5733107 B2 JP5733107 B2 JP 5733107B2 JP 2011184051 A JP2011184051 A JP 2011184051A JP 2011184051 A JP2011184051 A JP 2011184051A JP 5733107 B2 JP5733107 B2 JP 5733107B2
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和則 柴田
和則 柴田
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本発明は、ＦＳＫ信号検出装置、受信機、およびＦＳＫ信号検出方法に関する。   The present invention relates to an FSK signal detection device, a receiver, and an FSK signal detection method.

ＦＳＫ（Frequency Shift Keying：周波数偏移変調）デジタル受信機における消費電力を抑えるためには、ＦＳＫ信号が無い場合には、受信機を待機状態にする必要がある。しかし、プリアンブルが短い場合、ＦＳＫ信号を迅速に検出して待機状態から運用状態に復帰しなければ、データを受信することができない。   In order to suppress power consumption in an FSK (Frequency Shift Keying) digital receiver, it is necessary to place the receiver in a standby state when there is no FSK signal. However, if the preamble is short, data cannot be received unless the FSK signal is detected quickly to return from the standby state to the operating state.

信号検出方法として、電界強度による信号検出やスケルチ回路を用いた信号検出がある。また、特許文献１に開示されるＦＳＫ信号検出装置は、ＲＳＳＩ（Received Signal Strength Indicator：受信信号強度）やノイズスケルチなどを使用せずに、受信信号から抽出されるベースバンド信号のパワースペクトラム及びシンボルレートに基づき、ベースバンド信号中のＦＳＫ信号の有無を判定する。   Signal detection methods include signal detection using electric field strength and signal detection using a squelch circuit. Further, the FSK signal detection device disclosed in Patent Document 1 uses the power spectrum and symbols of a baseband signal extracted from a received signal without using RSSI (Received Signal Strength Indicator) or noise squelch. Based on the rate, the presence or absence of the FSK signal in the baseband signal is determined.

特開２００７−１６６２０８号公報JP 2007-166208 A

電界強度により信号検出を行う場合には、例えば、電化製品の近くなど、ＲＦ（Radio Frequency）信号のノイズフロアが大きい場所において受信機が誤って運用状態に復帰してしまうという問題がある。スケルチ回路を用いる信号検出方法では、音声歪みに対応するため、ＨＰＦ（High-Pass Filter：高域フィルタ）を介して高い周波数成分の信号を検出する。検出した信号の絶対値を算出し、ＬＰＦ（Low-Pass Filter：低域フィルタ）で平均化してスケルチレベルを算出するが、ＨＰＦで検出した信号は変動が大きい。より安定したスケルチレベルを得るためには、ＬＰＦのカットオフ周波数をより低くする必要がある。しかし、ＬＰＦのカットオフ周波数を低くすると、ＬＰＦのフィルタ通過時間が長くなる。そのため、信号検出が遅くなり、データを受信できない恐れがある。   When signal detection is performed based on electric field strength, for example, there is a problem in that a receiver erroneously returns to an operation state in a place where the noise floor of an RF (Radio Frequency) signal is large, such as near an electrical appliance. In a signal detection method using a squelch circuit, a signal having a high frequency component is detected via an HPF (High-Pass Filter) in order to cope with audio distortion. The absolute value of the detected signal is calculated and averaged by an LPF (Low-Pass Filter) to calculate the squelch level, but the signal detected by the HPF has a large fluctuation. In order to obtain a more stable squelch level, it is necessary to lower the cutoff frequency of the LPF. However, when the cutoff frequency of the LPF is lowered, the LPF filter passing time becomes longer. As a result, signal detection is delayed and data may not be received.

本発明は上述の事情に鑑みてなされたものであり、ＦＳＫ信号の検出を迅速化し、プリアンブルが短い場合でも、間欠受信を行っている受信機がデータを受信できる、ＦＳＫ信号検出装置、受信機、およびＦＳＫ信号検出方法を提供することを目的とする。   The present invention has been made in view of the above-described circumstances, and an FSK signal detection apparatus and receiver that can detect an FSK signal quickly and can receive data even when a preamble is short, even when a receiver that performs intermittent reception is received. And an FSK signal detection method.

上記目的を達成するため、本発明の第１の観点に係るＦＳＫ信号検出装置は、
受信信号をＦＭ検波し、前記受信信号の周波数に対応する振幅を有する復調信号を生成する、検波手段と、
前記復調信号から周波数が所定の値以上の周波数成分を抽出することで、ＤＣ成分を取り除き、ＤＣ成分の近傍の周波数成分を含む第１信号を生成する、第１抽出手段と、
前記第１抽出手段で生成された前記第１信号の絶対値を算出する、絶対値処理手段と、
カットオフ周波数がプリアンブルの時間長の逆数以上の所定の周波数である低域フィルタを用いて、前記第１信号の絶対値から前記カットオフ周波数以下の周波数成分を抽出し、第２信号を生成する、第２抽出手段と、
前記第２抽出手段で生成された前記第２信号の信号レベルが所定の範囲内の値であれば、前記受信信号にＦＳＫ信号が含まれていると判定する、判定手段と、
を備えることを特徴とする。 In order to achieve the above object, an FSK signal detection device according to the first aspect of the present invention provides:
Detecting means for FM detecting the received signal and generating a demodulated signal having an amplitude corresponding to the frequency of the received signal;
First extraction means for removing a DC component by extracting a frequency component having a frequency equal to or higher than a predetermined value from the demodulated signal, and generating a first signal including a frequency component in the vicinity of the DC component;
Absolute value processing means for calculating an absolute value of the first signal generated by the first extraction means;
Using a low-pass filter whose cutoff frequency is a predetermined frequency equal to or greater than the reciprocal of the preamble time length, a frequency component equal to or lower than the cutoff frequency is extracted from the absolute value of the first signal to generate a second signal. Second extraction means;
If signal level of the second signal generated by said second extraction means is a value within a predetermined range, determines that contains FSK signal in the received signal, and determining means,
It is characterized by providing.

好ましくは、前記第１抽出手段は、前記復調信号を前記復調信号のサンプリング間隔分だけ遅延させた遅延信号を生成し、前記復調信号と前記遅延信号の差分を検出することで、第１信号を生成する。   Preferably, the first extraction unit generates a delayed signal obtained by delaying the demodulated signal by a sampling interval of the demodulated signal, and detects a difference between the demodulated signal and the delayed signal, thereby obtaining the first signal. Generate.

好ましくは、前記ＦＳＫ信号検出装置は、前記判定手段の判定結果に基づき、前記低域フィルタのカットオフ周波数を変更する、制御手段をさらに備える。   Preferably, the FSK signal detection device further includes a control unit that changes a cutoff frequency of the low-pass filter based on a determination result of the determination unit.

本発明の第２の観点に係る受信機は、
前記ＦＳＫ信号検出装置と、
前記判定手段で前記受信信号にＦＳＫ信号が含まれていると判定された場合にのみ、ＦＳＫ復調および可聴周波数信号の生成を行う、復調手段と、
を備えることを特徴とする。 A receiver according to a second aspect of the present invention provides:
The FSK signal detection device;
Demodulation means for performing FSK demodulation and generation of an audible frequency signal only when the determination means determines that the received signal includes an FSK signal;
It is characterized by providing.

本発明の第３の観点に係るＦＳＫ信号検出方法は、
ＦＳＫ信号検出装置が行う、ＦＳＫ信号検出方法であって、
受信信号をＦＭ検波し、前記受信信号の周波数に対応する振幅を有する復調信号を生成する、検波ステップと、
前記復調信号から周波数が所定の値以上の周波数成分を抽出することで、ＤＣ成分を取り除き、ＤＣ成分の近傍の周波数成分を含む第１信号を生成する、第１抽出ステップと、
前記第１抽出ステップで生成された前記第１信号の絶対値を算出する、絶対値処理ステップと、
カットオフ周波数がプリアンブルの時間長の逆数以上の所定の周波数である低域フィルタを用いて、前記第１信号の絶対値から前記カットオフ周波数以下の周波数成分を抽出し、第２信号を生成する、第２抽出ステップと、
前記第２抽出ステップで生成された前記第２信号の信号レベルが所定の範囲内の値であれば、前記受信信号にＦＳＫ信号が含まれていると判定する、判定ステップと、
を備えることを特徴とする。 The FSK signal detection method according to the third aspect of the present invention is:
An FSK signal detection method performed by an FSK signal detection device,
A detection step of FM detecting the received signal and generating a demodulated signal having an amplitude corresponding to the frequency of the received signal;
Extracting a frequency component having a frequency equal to or higher than a predetermined value from the demodulated signal, thereby removing a DC component and generating a first signal including a frequency component in the vicinity of the DC component;
An absolute value processing step of calculating an absolute value of the first signal generated in the first extraction step;
Using a low-pass filter whose cutoff frequency is a predetermined frequency equal to or greater than the reciprocal of the preamble time length, a frequency component equal to or lower than the cutoff frequency is extracted from the absolute value of the first signal to generate a second signal. A second extraction step;
If signal level of the second signal generated by said second extraction step is a value within a predetermined range, it determines that contains FSK signal in the received signal, and determining step,
It is characterized by providing.

好ましくは、前記第１抽出ステップにおいて、前記復調信号を前記復調信号のサンプリング間隔分だけ遅延させた遅延信号を生成し、前記復調信号と前記遅延信号の差分を検出することで、第１信号を生成する。   Preferably, in the first extraction step, a delayed signal is generated by delaying the demodulated signal by a sampling interval of the demodulated signal, and a difference between the demodulated signal and the delayed signal is detected, whereby the first signal is obtained. Generate.

好ましくは、前記ＦＳＫ信号検出方法は、前記判定ステップの判定結果に基づき、前記低域フィルタのカットオフ周波数を変更する、制御ステップをさらに備える。   Preferably, the FSK signal detection method further includes a control step of changing a cutoff frequency of the low-pass filter based on a determination result of the determination step.

本発明によれば、ＦＳＫ信号の検出を迅速化し、プリアンブルが短い場合でも、間欠受信を行っている受信機がデータを受信できる、ＦＳＫ信号検出装置、受信機、およびＦＳＫ信号検出方法を提供することが可能となる。   According to the present invention, it is possible to provide an FSK signal detection device, a receiver, and an FSK signal detection method capable of speeding up detection of an FSK signal and allowing a receiver performing intermittent reception to receive data even when the preamble is short. It becomes possible.

本発明の実施の形態１に係るＦＳＫ信号検出装置の構成例を示すブロック図である。It is a block diagram which shows the structural example of the FSK signal detection apparatus which concerns on Embodiment 1 of this invention. 実施の形態１における差分検出部の周波数特性の例を示す図である。6 is a diagram illustrating an example of frequency characteristics of a difference detection unit according to Embodiment 1. FIG. 実施の形態１におけるＳＮ比が小さいデジタル信号の復調信号の周波数特性の例を示す図である。7 is a diagram illustrating an example of frequency characteristics of a demodulated signal of a digital signal having a small SN ratio in the first embodiment. FIG. 本発明の実施の形態２に係るＦＳＫ信号検出装置の構成例を示すブロック図である。It is a block diagram which shows the structural example of the FSK signal detection apparatus which concerns on Embodiment 2 of this invention. 本発明の実施の形態３に係る受信機の構成例を示すブロック図である。It is a block diagram which shows the structural example of the receiver which concerns on Embodiment 3 of this invention.

以下、本発明の実施の形態について図面を参照して詳細に説明する。なお図中、同一または同等の部分には同一の符号を付す。   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals.

（実施の形態１）
図１は、本発明の実施の形態１に係るＦＳＫ信号検出装置の構成例を示すブロック図である。ＦＳＫ信号検出装置１（以下、検出装置１と記す）は、アンテナ１１、受信部１２、検波部１３、遅延部１４、差分検出部１５、絶対値処理部１６、ＬＰＦ１７、および判定部１８を備える。受信部１２は、アンテナ１１で受信した受信信号の高周波数から中間周波数への周波数変換、増幅などを行い、検波部１３に受信信号を送る。検波部１３は、受信信号をＦＭ検波し、受信信号の周波数に対応する振幅を有する復調信号を生成する。そして、生成した復調信号を遅延部１４および差分検出部１５に送る。 (Embodiment 1)
FIG. 1 is a block diagram showing a configuration example of an FSK signal detection apparatus according to Embodiment 1 of the present invention. The FSK signal detection device 1 (hereinafter referred to as the detection device 1) includes an antenna 11, a reception unit 12, a detection unit 13, a delay unit 14, a difference detection unit 15, an absolute value processing unit 16, an LPF 17, and a determination unit 18. . The reception unit 12 performs frequency conversion, amplification, and the like of the reception signal received by the antenna 11 from a high frequency to an intermediate frequency, and sends the reception signal to the detection unit 13. The detection unit 13 performs FM detection on the received signal, and generates a demodulated signal having an amplitude corresponding to the frequency of the received signal. Then, the generated demodulated signal is sent to the delay unit 14 and the difference detection unit 15.

検出装置１は、遅延部１４および差分検出部１５を用いて、周波数が所定の値以上の周波数成分を抽出し、第１信号を生成する。遅延部１４は、送られた復調信号を復調信号のサンプリング間隔分だけ遅延させた遅延信号を生成し、生成した遅延信号を差分検出部１５に送る。サンプリング間隔は、ＦＳＫ信号のシンボル期間に比べて十分小さい値であり、例えば、シンボル期間の１０分の１の値を用いる。差分検出部１５は、復調信号と遅延信号の差分を検出し、第１信号を生成する。そして、生成した第１信号を絶対値処理部１６に送る。   The detection apparatus 1 uses the delay unit 14 and the difference detection unit 15 to extract a frequency component having a frequency equal to or higher than a predetermined value, and generates a first signal. The delay unit 14 generates a delay signal obtained by delaying the transmitted demodulated signal by the sampling interval of the demodulated signal, and sends the generated delay signal to the difference detection unit 15. The sampling interval is a sufficiently small value compared to the symbol period of the FSK signal, and for example, a value of 1/10 of the symbol period is used. The difference detection unit 15 detects a difference between the demodulated signal and the delayed signal and generates a first signal. Then, the generated first signal is sent to the absolute value processing unit 16.

図２は、実施の形態１における差分検出部の周波数特性の例を示す図である。図２の例に示すように、差分検出部１５は、減衰傾度の緩やかなＨＰＦとして動作する。減衰傾度が緩やかなため、復調信号からＤＣ成分は取り除かれるが、比較的周波数が低いＤＣ成分の近傍の周波数成分は第１信号に含まれる。   FIG. 2 is a diagram illustrating an example of frequency characteristics of the difference detection unit according to the first embodiment. As shown in the example of FIG. 2, the difference detection unit 15 operates as an HPF having a gentle attenuation gradient. Since the attenuation gradient is gentle, the DC component is removed from the demodulated signal, but the frequency component near the DC component having a relatively low frequency is included in the first signal.

図３は、実施の形態１におけるＳＮ比が小さいデジタル信号の復調信号の周波数特性の例を示す図である。ＳＮ比が小さいデジタル信号をＦＭ検波すると、パルス性ノイズが発生するため、復調信号は図３の例に示すような周波数特性を有する。   FIG. 3 is a diagram illustrating an example of frequency characteristics of a demodulated signal of a digital signal having a small SN ratio in the first embodiment. When a digital signal having a small S / N ratio is FM-detected, pulse noise is generated. Therefore, the demodulated signal has frequency characteristics as shown in the example of FIG.

ＦＳＫ信号は、アナログＦＭとは異なり歪みの影響を受けにくい。ＦＳＫ変調で用いられる周波数偏差は一定であり、ＦＳＫ信号には常にＦＳＫ変調が加えられている。また、ベースバンド周波数が低い。そのため、例えば、スケルチ回路の様にノイズ検出用にカットオフ周波数が２０ｋＨｚ以上である、カットオフ周波数の高いＨＰＦを用いずに、復調信号と遅延信号の差分を検出することでＤＣ成分を取り除き、ＦＳＫ信号が含まれる比較的周波数が低いＤＣ成分の近傍の周波数成分を含む第１信号を生成することができる。   Unlike the analog FM, the FSK signal is less susceptible to distortion. The frequency deviation used in the FSK modulation is constant, and the FSK modulation is always applied to the FSK signal. Also, the baseband frequency is low. Therefore, for example, the DC component is removed by detecting the difference between the demodulated signal and the delayed signal without using a high cutoff frequency HPF having a cutoff frequency of 20 kHz or more for noise detection like a squelch circuit, A first signal including a frequency component in the vicinity of a DC component having a relatively low frequency including the FSK signal can be generated.

絶対値処理部１６は、送られた第１信号の絶対値を算出し、第１信号の絶対値をＬＰＦ１７に送る。ＬＰＦ１７は、送られた第１信号の絶対値からカットオフ周波数以下の周波数成分を抽出し、第２信号を生成する。そして、生成した第２信号を判定部１８に送る。ＬＰＦ１７により、第２信号に含まれるノイズ成分が平均化される。カットオフ周波数は、プリアンブルの時間長の逆数以上の任意の値である。   The absolute value processing unit 16 calculates the absolute value of the sent first signal and sends the absolute value of the first signal to the LPF 17. The LPF 17 extracts a frequency component equal to or lower than the cutoff frequency from the absolute value of the transmitted first signal, and generates a second signal. Then, the generated second signal is sent to the determination unit 18. The LPF 17 averages the noise component included in the second signal. The cutoff frequency is an arbitrary value equal to or greater than the reciprocal of the preamble time length.

ＦＳＫ信号が含まれるＤＣ成分の近傍の周波数成分は、第２信号にも含まれているので、ＬＰＦ１７のカットオフ周波数を高くすることが可能となる。カットオフ周波数を高くすると、ＬＰＦ１７のフィルタ通過時間が短くなり、ＦＳＫ信号の検出も速くなる。そのため、プリアンブルが短い場合でも、検出装置１はＦＳＫ信号の有無を検出することができる。   Since the frequency component in the vicinity of the DC component including the FSK signal is also included in the second signal, the cutoff frequency of the LPF 17 can be increased. When the cutoff frequency is increased, the filter passing time of the LPF 17 is shortened, and the detection of the FSK signal is also accelerated. Therefore, even when the preamble is short, the detection device 1 can detect the presence or absence of the FSK signal.

判定部１８は、第２信号の所定の周波数における信号レベルが所定の範囲内の値であれば、受信信号にＦＳＫ信号が含まれていると判定する。判定部１８は、判定結果を検出装置１の外部に通知する。その通知に基づき、例えば検出装置１を備える受信機は運用状態と待機状態の切り替えを行う。所定の周波数とは、ＦＳＫ信号が含まれるＤＣ成分の近傍の任意の周波数である。   The determination unit 18 determines that the FSK signal is included in the received signal if the signal level at the predetermined frequency of the second signal is a value within a predetermined range. The determination unit 18 notifies the determination result to the outside of the detection device 1. Based on the notification, for example, a receiver including the detection device 1 switches between an operation state and a standby state. The predetermined frequency is an arbitrary frequency in the vicinity of the DC component including the FSK signal.

ＦＳＫ信号の信号レベルが下がっても、第２信号に含まれるＤＣ成分の近傍の周波数における信号レベルが所定の範囲内の値であれば、ＦＳＫ信号を検出することができる。またスケルチ回路では、受信信号の有無を判定することはできるが、ＦＳＫ信号、アナログＦＭ信号、差動四相位相偏移変調信号などの受信信号の種類を区別することができない。一方、実施の形態１に係る検出装置１は、ＦＳＫ信号の有無を判定することができる。   Even if the signal level of the FSK signal decreases, the FSK signal can be detected if the signal level at a frequency in the vicinity of the DC component included in the second signal is a value within a predetermined range. The squelch circuit can determine the presence or absence of a received signal, but cannot distinguish the type of received signal such as an FSK signal, an analog FM signal, or a differential quadrature phase shift keying signal. On the other hand, the detection apparatus 1 according to Embodiment 1 can determine the presence or absence of the FSK signal.

以上説明したとおり、本発明の実施の形態１に係る検出装置１によれば、ＦＳＫ信号の検出を迅速化し、プリアンブルが短い場合でも、間欠受信を行っている受信機がデータを受信することが可能となる。   As described above, according to the detection apparatus 1 according to the first embodiment of the present invention, the detection of the FSK signal is speeded up, and even when the preamble is short, the receiver performing intermittent reception can receive data. It becomes possible.

（実施の形態２）
図４は、本発明の実施の形態２に係るＦＳＫ信号検出装置の構成例を示すブロック図である。検出装置１は、実施の形態１の検出装置１の構成に加え、ＬＰＦ制御部１９を備える。ＬＰＦ制御部１９は、判定部１８の判定結果に基づき、ＬＰＦ１７のカットオフ周波数の値を変更する。カットオフ周波数の値を高くすると、ＬＰＦ１７のフィルタ通過時間が短くなり、ＦＳＫ信号の検出速度も速くなる。また、判定部１８でＦＳＫ信号が有ると判定された場合には、カットオフ周波数の値を低くし、第２信号に対する一時的なノイズの影響を少なくすることができる。 (Embodiment 2)
FIG. 4 is a block diagram showing a configuration example of the FSK signal detection apparatus according to Embodiment 2 of the present invention. The detection device 1 includes an LPF control unit 19 in addition to the configuration of the detection device 1 of the first embodiment. The LPF control unit 19 changes the value of the cutoff frequency of the LPF 17 based on the determination result of the determination unit 18. When the value of the cutoff frequency is increased, the filter passing time of the LPF 17 is shortened, and the detection speed of the FSK signal is also increased. Further, when the determination unit 18 determines that there is an FSK signal, the value of the cutoff frequency can be lowered to reduce the influence of temporary noise on the second signal.

ＬＰＦ制御部１９を備えることで、検出装置１を備える受信機が待機状態から運用状態に切り替わる際のＦＳＫ信号の信号レベルと運用状態から待機状態に切り替わる際のＦＳＫ信号の信号レベルとの間にヒステリシス特性を持たせることが可能となる。   By including the LPF control unit 19, between the signal level of the FSK signal when the receiver including the detection device 1 is switched from the standby state to the operating state and the signal level of the FSK signal when the receiver is switched from the operating state to the standby state. It is possible to provide hysteresis characteristics.

以上説明したとおり、本発明の実施の形態２に係る検出装置１によれば、ＬＰＦ１７のカットオフ周波数を動的に変化させ、カットオフ周波数を高くすることで、ＦＳＫ信号の検出を速くすることが可能となる。また、運用状態と待機状態の切り替えにヒステリシス特性を持たせることが可能となる。   As described above, according to the detection apparatus 1 according to Embodiment 2 of the present invention, the detection of the FSK signal is accelerated by dynamically changing the cutoff frequency of the LPF 17 and increasing the cutoff frequency. Is possible. Further, it is possible to provide hysteresis characteristics for switching between the operation state and the standby state.

（実施の形態３）
図５は、本発明の実施の形態３に係る受信機の構成例を示すブロック図である。受信機２は、実施の形態２の検出装置１および復調部２１を備える。検波部１３は、受信信号を復調部２１に送る。検出装置１内の判定部１８は、ＦＳＫ信号の有無の判定結果を復調部２１に送る。復調部２１は、受信信号にＦＳＫ信号が含まれていると判定された場合にのみ、ＦＳＫ復調およびＡＦ（Audio Frequency：可聴周波数）信号の生成を行う。 (Embodiment 3)
FIG. 5 is a block diagram showing a configuration example of a receiver according to Embodiment 3 of the present invention. The receiver 2 includes the detection device 1 and the demodulation unit 21 according to the second embodiment. The detector 13 sends the received signal to the demodulator 21. The determination unit 18 in the detection device 1 sends the determination result of the presence or absence of the FSK signal to the demodulation unit 21. The demodulator 21 performs FSK demodulation and AF (Audio Frequency) signal generation only when it is determined that the FSK signal is included in the received signal.

以上説明したとおり、本発明の実施の形態３に係る受信機２によれば、受信信号にＦＳＫ信号が含まれていると判定された場合にのみＦＳＫ復調およびＡＦ信号の生成を行い、受信機２の消費電力を抑えることが可能となる。   As described above, the receiver 2 according to Embodiment 3 of the present invention performs FSK demodulation and AF signal generation only when it is determined that the FSK signal is included in the received signal, and the receiver 2 can be reduced.

本発明の実施の形態は上述の実施の形態に限られない。実施の形態３の受信機２は、実施の形態１の検出装置１を備えるよう構成してもよい。   The embodiment of the present invention is not limited to the above-described embodiment. The receiver 2 of the third embodiment may be configured to include the detection device 1 of the first embodiment.

検出装置１は、布線論理回路、ＤＳＰ（デジタルシグナルプロセッサ）、布線論理回路とＤＳＰの組み合わせなどで構成することができる。また判定部１８およびＬＰＦ制御部１９は、マイクロプロセッサを用いて構成することができる。   The detection device 1 can be configured by a wiring logic circuit, a DSP (digital signal processor), a combination of a wiring logic circuit and a DSP, and the like. The determination unit 18 and the LPF control unit 19 can be configured using a microprocessor.

１ ＦＳＫ信号検出装置
２ 受信機
１１ アンテナ
１２ 受信部
１３ 検波部
１４ 遅延部
１５ 差分検出部
１６ 絶対値処理部
１７ ＬＰＦ
１８ 判定部
１９ ＬＰＦ制御部
２１ 復調部
DESCRIPTION OF SYMBOLS 1 FSK signal detection apparatus 2 Receiver 11 Antenna 12 Receiving part 13 Detection part 14 Delay part 15 Difference detection part 16 Absolute value process part 17 LPF
18 Judgment Unit 19 LPF Control Unit 21 Demodulation Unit

Claims (7)

受信信号をＦＭ検波し、前記受信信号の周波数に対応する振幅を有する復調信号を生成する、検波手段と、
前記復調信号から周波数が所定の値以上の周波数成分を抽出することで、ＤＣ成分を取り除き、ＤＣ成分の近傍の周波数成分を含む第１信号を生成する、第１抽出手段と、
前記第１抽出手段で生成された前記第１信号の絶対値を算出する、絶対値処理手段と、
カットオフ周波数がプリアンブルの時間長の逆数以上の所定の周波数である低域フィルタを用いて、前記第１信号の絶対値から前記カットオフ周波数以下の周波数成分を抽出し、第２信号を生成する、第２抽出手段と、
前記第２抽出手段で生成された前記第２信号の信号レベルが所定の範囲内の値であれば、前記受信信号にＦＳＫ信号が含まれていると判定する、判定手段と、
を備えることを特徴とするＦＳＫ信号検出装置。 Detecting means for FM detecting the received signal and generating a demodulated signal having an amplitude corresponding to the frequency of the received signal;
First extraction means for removing a DC component by extracting a frequency component having a frequency equal to or higher than a predetermined value from the demodulated signal, and generating a first signal including a frequency component in the vicinity of the DC component;
Absolute value processing means for calculating an absolute value of the first signal generated by the first extraction means;
Using a low-pass filter whose cutoff frequency is a predetermined frequency equal to or greater than the reciprocal of the preamble time length, a frequency component equal to or lower than the cutoff frequency is extracted from the absolute value of the first signal to generate a second signal. Second extraction means;
If signal level of the second signal generated by said second extraction means is a value within a predetermined range, determines that contains FSK signal in the received signal, and determining means,
An FSK signal detection apparatus comprising: 前記第１抽出手段は、前記復調信号を前記復調信号のサンプリング間隔分だけ遅延させた遅延信号を生成し、前記復調信号と前記遅延信号の差分を検出することで、第１信号を生成することを特徴とする請求項１に記載のＦＳＫ信号検出装置。   The first extraction unit generates a delayed signal obtained by delaying the demodulated signal by a sampling interval of the demodulated signal, and generates a first signal by detecting a difference between the demodulated signal and the delayed signal. The FSK signal detection device according to claim 1. 前記判定手段の判定結果に基づき、前記低域フィルタのカットオフ周波数を変更する、制御手段をさらに備えることを特徴とする請求項１または２に記載のＦＳＫ信号検出装置。   The FSK signal detection apparatus according to claim 1, further comprising a control unit that changes a cutoff frequency of the low-pass filter based on a determination result of the determination unit. 請求項１ないし３のいずれか１項に記載のＦＳＫ信号検出装置と、
前記判定手段で前記受信信号にＦＳＫ信号が含まれていると判定された場合にのみ、ＦＳＫ復調および可聴周波数信号の生成を行う、復調手段と、
を備えることを特徴とする受信機。 The FSK signal detection device according to any one of claims 1 to 3,
Demodulation means for performing FSK demodulation and generation of an audible frequency signal only when the determination means determines that the received signal includes an FSK signal;
A receiver comprising: ＦＳＫ信号検出装置が行う、ＦＳＫ信号検出方法であって、
受信信号をＦＭ検波し、前記受信信号の周波数に対応する振幅を有する復調信号を生成する、検波ステップと、
前記復調信号から周波数が所定の値以上の周波数成分を抽出することで、ＤＣ成分を取り除き、ＤＣ成分の近傍の周波数成分を含む第１信号を生成する、第１抽出ステップと、
前記第１抽出ステップで生成された前記第１信号の絶対値を算出する、絶対値処理ステップと、
カットオフ周波数がプリアンブルの時間長の逆数以上の所定の周波数である低域フィルタを用いて、前記第１信号の絶対値から前記カットオフ周波数以下の周波数成分を抽出し、第２信号を生成する、第２抽出ステップと、
前記第２抽出ステップで生成された前記第２信号の信号レベルが所定の範囲内の値であれば、前記受信信号にＦＳＫ信号が含まれていると判定する、判定ステップと、
を備えることを特徴とするＦＳＫ信号検出方法。 An FSK signal detection method performed by an FSK signal detection device,
A detection step of FM detecting the received signal and generating a demodulated signal having an amplitude corresponding to the frequency of the received signal;
Extracting a frequency component having a frequency equal to or higher than a predetermined value from the demodulated signal, thereby removing a DC component and generating a first signal including a frequency component in the vicinity of the DC component;
An absolute value processing step of calculating an absolute value of the first signal generated in the first extraction step;
Using a low-pass filter whose cutoff frequency is a predetermined frequency equal to or greater than the reciprocal of the preamble time length, a frequency component equal to or lower than the cutoff frequency is extracted from the absolute value of the first signal to generate a second signal. A second extraction step;
If signal level of the second signal generated by said second extraction step is a value within a predetermined range, it determines that contains FSK signal in the received signal, and determining step,
An FSK signal detection method comprising: 前記第１抽出ステップにおいて、前記復調信号を前記復調信号のサンプリング間隔分だけ遅延させた遅延信号を生成し、前記復調信号と前記遅延信号の差分を検出することで、第１信号を生成することを特徴とする請求項５に記載のＦＳＫ信号検出方法。   In the first extraction step, a delayed signal is generated by delaying the demodulated signal by a sampling interval of the demodulated signal, and a first signal is generated by detecting a difference between the demodulated signal and the delayed signal. The FSK signal detection method according to claim 5. 前記判定ステップの判定結果に基づき、前記低域フィルタのカットオフ周波数を変更する、制御ステップをさらに備えることを特徴とする請求項５または６に記載のＦＳＫ信号検出方法。   The FSK signal detection method according to claim 5 or 6, further comprising a control step of changing a cutoff frequency of the low-pass filter based on a determination result of the determination step.
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