JP5033065B2 - FSK demodulator - Google Patents

FSK demodulator Download PDF

Info

Publication number
JP5033065B2
JP5033065B2 JP2008154531A JP2008154531A JP5033065B2 JP 5033065 B2 JP5033065 B2 JP 5033065B2 JP 2008154531 A JP2008154531 A JP 2008154531A JP 2008154531 A JP2008154531 A JP 2008154531A JP 5033065 B2 JP5033065 B2 JP 5033065B2
Authority
JP
Japan
Prior art keywords
frequency
fsk
amplitude
pass filter
low
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP2008154531A
Other languages
Japanese (ja)
Other versions
JP2009302862A (en
Inventor
武 稲垣
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
New Japan Radio Co Ltd
Original Assignee
New Japan Radio Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by New Japan Radio Co Ltd filed Critical New Japan Radio Co Ltd
Priority to JP2008154531A priority Critical patent/JP5033065B2/en
Publication of JP2009302862A publication Critical patent/JP2009302862A/en
Application granted granted Critical
Publication of JP5033065B2 publication Critical patent/JP5033065B2/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Landscapes

  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

Description

本発明は、受信したＦＳＫ（周波数シフトキーイング）変調信号の復調を行うＦＳＫ復調器に関するものである。   The present invention relates to an FSK demodulator that demodulates a received FSK (frequency shift keying) modulated signal.

ＦＳＫ復調器は、アナログ方式、デジタル方式ともに多種多様な方式がある。図６は、従来のクァドラクチャ方式のＦＳＫ復調器５０の構成を示すブロック図である。このＦＳＫ復調器５０は、前置ローパスフィルタ５１、乗算器５２、移相器５３、後置ローパスフィルタ５４、閾値設定器５５、比較器５６からなる。   There are a wide variety of FSK demodulators, both analog and digital. FIG. 6 is a block diagram showing a configuration of a conventional quadrature FSK demodulator 50. The FSK demodulator 50 includes a pre-pass low-pass filter 51, a multiplier 52, a phase shifter 53, a post-pass low-pass filter 54, a threshold setting unit 55, and a comparator 56.

電圧パルス信号であるＦＳＫ変調信号Ｓ１０は、前置ローパスフィルタ５１により基本周波数より大きな周波数成分が減衰され、後段の乗算器５２及び移相器５３へ入力される。乗算器５２においては、前置ローパスフィルタ５１の出力信号と移相器５３の出力が乗算される。このとき、Ａを振幅、ωを基本波の角周波数、θを時刻ｔ＝０での初期位相とすると、前置ローパスフィルタ５１の出力信号Ｓ１５は、
Ｓ１５＝Ａ・ｃｏｓ（ωｔ＋θ）
で表される。移相器５３での位相変化量をαとすると、乗算器５２の出力信号Ｓ１６は、
Ｓ１６＝Ａ・ｃｏｓ（ωｔ＋θ）×Ａ・ｃｏｓ（ωｔ＋θ＋α）
＝０．５・Ａ２・［ｃｏｓα＋ｃｏｓ{２（ωｔ＋θ）＋α}］
となる。さらに、ＦＳＫ変調信号の基本周波数より大きな周波数成分を減衰させる後置ローパスフィルタ５４の出力信号Ｓ１７は、
Ｓ１７＝０．５・Ａ２・ｃｏｓα
となり、移相器５３での位相変化量αに応じた直流成分が得られる。 The FSK modulation signal S10, which is a voltage pulse signal, is attenuated in frequency components larger than the fundamental frequency by the pre-pass filter 51 and input to the subsequent multiplier 52 and phase shifter 53. In the multiplier 52, the output signal of the pre-pass filter 51 and the output of the phase shifter 53 are multiplied. At this time, if A is the amplitude, ω is the angular frequency of the fundamental wave, and θ is the initial phase at time t = 0, the output signal S15 of the pre-low pass filter 51 is
S15 = A · cos (ωt + θ)
It is represented by When the phase change amount in the phase shifter 53 is α, the output signal S16 of the multiplier 52 is
S16 = A · cos (ωt + θ) × A · cos (ωt + θ + α)
= 0.5 · A 2 [[cos α + cos {2 (ωt + θ) + α}]
It becomes. Furthermore, the output signal S17 of the post-low-pass filter 54 that attenuates a frequency component larger than the fundamental frequency of the FSK modulation signal is:
S17 = 0.5 · A 2 · cos α
Thus, a direct current component corresponding to the phase change amount α in the phase shifter 53 is obtained.

よって、移相器５３での位相変化量αを周波数に応じて変化させることで、周波数の変化を振幅の変化に変換できる。一般に、クァドラチャ方式では、移相器５３での位相回転量αをＦＳＫ変調信号の中心周波数において９０度の奇数倍とすることで、ＦＳＫ変調信号の中心周波数の信号が入力された場合には、後置ローパスフィルタ５４の出力はゼロ（ｃｏｓα＝０）となる。このとき、ＦＳＫ変調信号の中心周波数に対する上側周波数と下側周波数の信号が入力された場合には、後置ローパスフィルタ５４の出力には正負の値が得られ、閾値設定器５５の閾値をゼロとすれば、比較器５６の符号判定によってＦＳＫ復調信号が得られる。クァドラチャ方式のＦＳＫ復調回路については、例えば特許文献１に記載されている。
特開平１０−２６１９２０号公報 Therefore, the change in frequency can be converted into the change in amplitude by changing the phase change amount α in the phase shifter 53 according to the frequency. In general, in the quadrature method, when the phase rotation amount α in the phase shifter 53 is an odd multiple of 90 degrees at the center frequency of the FSK modulation signal, when the signal of the center frequency of the FSK modulation signal is input, The output of the post-pass low-pass filter 54 becomes zero (cos α = 0). At this time, when an upper frequency signal and a lower frequency signal with respect to the center frequency of the FSK modulation signal are input, positive and negative values are obtained at the output of the post-low-pass filter 54, and the threshold value of the threshold setting unit 55 is set to zero. Then, the FSK demodulated signal is obtained by the code determination of the comparator 56. A quadrature FSK demodulator circuit is described in, for example, Patent Document 1.
JP-A-10-261920

ところが、上記のようなクァドラチャ方式では、移相器５３において、ＦＳＫ変調信号の中心周波数での位相回転量αが９０度の奇数倍からずれると、ＦＳＫ変調信号の中心周波数の信号が入力された場合に、後置ローパスフィルタ５４の出力はゼロではなくなり、オフセットが生じる。このとき、ＦＳＫ変調信号の上側周波数と下側周波数の信号が入力された場合の後置ローパスフィルタ５４の出力信号は、位相回転量αのずれが大きい場合には、後置ローパスフィルタ５４で生じるオフセットも大きく、正又は負の値での振幅変化しか得られず、最悪の場合には閾値設定器５５の閾値をゼロとした比較器５６では符号判定ができない。   However, in the quadrature system as described above, when the phase rotation amount α at the center frequency of the FSK modulation signal deviates from an odd multiple of 90 degrees in the phase shifter 53, a signal at the center frequency of the FSK modulation signal is input. In some cases, the output of the post-pass low-pass filter 54 is not zero and an offset occurs. At this time, the output signal of the post-pass low-pass filter 54 when the signal of the upper frequency and the lower frequency of the FSK modulation signal is input is generated by the post-pass low-pass filter 54 when the shift of the phase rotation amount α is large. The offset is large, and only a positive or negative amplitude change can be obtained. In the worst case, the comparator 56 in which the threshold value of the threshold value setting unit 55 is zero cannot be used for sign determination.

また、位相回転量αのずれが小さい場合でも、オフセットによりＦＳＫ復調信号は、符号「１」の期間と符号「０」の期間でのアンバランス、すなわち波形のデューティ比が５０％からずれたものとなる。このため、符号判定動作の実現はもとより、ＦＳＫ復調信号のデューティ比を５０％にするためには、移相器５３での位相回転量αあるいは閾値設定器５５の閾値調整が必要となる。   Further, even when the deviation of the phase rotation amount α is small, the FSK demodulated signal is unbalanced between the period of the code “1” and the period of the code “0” due to the offset, that is, the duty ratio of the waveform deviates from 50%. It becomes. Therefore, in addition to realizing the code determination operation, in order to set the duty ratio of the FSK demodulated signal to 50%, the phase rotation amount α in the phase shifter 53 or the threshold adjustment of the threshold setting unit 55 is required.

また、環境変動や製造バラツキなどの様々な変動条件が生じた場合でも、安定な符号判定動作を得るためには、構成部品の選別や自動調整機能の追加が必要となる。   In addition, even when various fluctuation conditions such as environmental fluctuations and manufacturing variations occur, in order to obtain a stable code determination operation, it is necessary to select components and add an automatic adjustment function.

本発明の目的は、上記問題点を解消し、調整が不要なＦＳＫ復調器を提供することである。   An object of the present invention is to solve the above problems and provide an FSK demodulator that does not require adjustment.

上記目的を達成するために、請求項１にかかる発明のＦＳＫ復調器は、ＦＳＫ変調信号を入力し周波数に応じた振幅信号に変換する第１の周波数振幅変換部と、前記ＦＳＫ変調信号の中心周波数信号を入力し前記第１の周波数振幅変換部と構成が共通の第２の周波数振幅変換部とを備え、前記第１の周波数振幅変換部の出力信号振幅と前記第２の周波数振幅変換部の出力信号振幅とを比較することにより符号判定を行うＦＳＫ復調器において、前記第１および第２の周波数振幅変換部を、前記中心周波数が減衰域にあるような周波数特性をもつ前置ローパスフィルタと、該前置ローパスフィルタの出力の交流成分を全波整流する全波整流回路と、該全波整流回路の出力から前記中心周波数より高い周波数成分を減衰させる後置ローパスフィルタとから構成した、ことを特徴とする。
請求項２にかかる発明は、請求項１に記載のＦＳＫ復調器において、前記全波整流回路を、前記前置ローパスフィルタの出力の交流成分を二乗する二乗回路に置き換えたことを特徴とする。
請求項３にかかる発明は、請求項１に記載のＦＳＫ復調器において、前記全波整流回路を、前記前置ローパスフィルタの出力信号の周波数に応じて移相量が変化し且つ前記ＦＳＫ変調信号の中心周波数での該移相量が９０度の奇数倍となる移相器と、該移相器の出力信号と前記前置ローパスフィルタの出力信号とを乗算し前記後置ローパスフィルタに出力する乗算器とからなる回路に置き換えたことを特徴とする。
In order to achieve the above object, an FSK demodulator according to a first aspect of the present invention includes a first frequency-amplitude converter that receives an FSK-modulated signal and converts it into an amplitude signal corresponding to the frequency, and the center of the FSK-modulated signal. A second frequency amplitude conversion unit that receives a frequency signal and has the same configuration as the first frequency amplitude conversion unit; and an output signal amplitude of the first frequency amplitude conversion unit and the second frequency amplitude conversion unit In the FSK demodulator for determining the sign by comparing the output signal amplitude of the first and second frequency amplitude converters, the first and second frequency amplitude converters are provided with a low-pass filter having a frequency characteristic such that the center frequency is in the attenuation region. A full-wave rectifier circuit that full-wave rectifies the alternating current component of the output of the front-pass low-pass filter, and a post-pass low-pass filter that attenuates a frequency component higher than the center frequency from the output of the full-wave rectifier circuit Was composed of a, characterized in that.
According to a second aspect of the present invention, in the FSK demodulator according to the first aspect, the full-wave rectifier circuit is replaced with a square circuit that squares the AC component of the output of the pre-low pass filter .
According to a third aspect of the present invention, in the FSK demodulator according to the first aspect , the full-wave rectifier circuit is configured such that the amount of phase shift changes according to the frequency of the output signal of the pre-low pass filter and the FSK modulated signal. A phase shifter whose phase shift amount at the center frequency is an odd multiple of 90 degrees, and the output signal of the phase shifter multiplied by the output signal of the pre-pass low-pass filter and output to the post-pass low-pass filter The circuit is replaced by a circuit comprising a multiplier .

本発明によれば、構成が共通の第１および第２の周波数振幅変換部を備え、第１の周波数振幅変換部でＦＳＫ変調信号を振幅信号に変換し、第２の周波数振幅変換部でＦＳＫ変調信号の中心周波数を振幅信号に変換するものであり、第２の周波数振幅変換部の出力信号は第１の周波数振幅変換部の出力信号の振幅の中心値となるので、両者の出力信号を比較判定することにより、第１および第２の周波数振幅変換部の調整が不要で所定デューティ比のＦＳＫ復調信号を得ることができる。   According to the present invention, the first and second frequency amplitude conversion units having the same configuration are provided, the FSK modulation signal is converted into an amplitude signal by the first frequency amplitude conversion unit, and the FSK is converted by the second frequency amplitude conversion unit. The center frequency of the modulation signal is converted into an amplitude signal, and the output signal of the second frequency amplitude conversion unit becomes the center value of the amplitude of the output signal of the first frequency amplitude conversion unit. By performing the comparison determination, it is not necessary to adjust the first and second frequency amplitude conversion units, and an FSK demodulated signal having a predetermined duty ratio can be obtained.

特に、ＦＳＫ復調の精度は、第１および第２の周波数振幅変換部の相対精度で決まるため、これらを良好な相対精度が得られる同一プロセスによる半導体集積回路で構成することにより、環境変動や製造バラツキなどの様々な変動条件に対しても、調整が不要なＦＳＫ復調器を実現できる。   In particular, since the accuracy of FSK demodulation is determined by the relative accuracy of the first and second frequency / amplitude converters, by configuring these with a semiconductor integrated circuit using the same process that can obtain good relative accuracy, environmental fluctuations and manufacturing It is possible to realize an FSK demodulator that does not require adjustment even under various fluctuation conditions such as variations.

＜第１の実施例＞
図１は、本発明の第１の実施例のＦＳＫ復調器１０の構成を示すブロック図である。本実施例のＦＳＫ復調器１０は、第１および第２の周波数振幅変換部２０，３０と振幅比較を行う比較器４０で構成される。また、第１の周波数振幅変換部２０にはＦＳＫ変調信号Ｓ１０が入力され、第２の周波数振幅変換部３０にはＦＳＫ中心周波数信号Ｓ２０が入力され、比較器４０からＦＳＫ復調信号Ｓ３０が出力される。 <First embodiment>
FIG. 1 is a block diagram showing the configuration of the FSK demodulator 10 according to the first embodiment of the present invention. The FSK demodulator 10 according to the present embodiment includes a first and second frequency / amplitude converters 20 and 30 and a comparator 40 that performs amplitude comparison. Further, the FSK modulation signal S10 is input to the first frequency amplitude converter 20, the FSK center frequency signal S20 is input to the second frequency amplitude converter 30, and the FSK demodulated signal S30 is output from the comparator 40. The

第１の周波数振幅変換部２０は前置ローパスフィルタ２１、全波整流回路２２、後置ローパスフィルタ２３を順次縦続接続した構成であり、第２の周波数振幅変換部３０は前置ローパスフィルタ３１、全波整流回路３２、後置ローパスフィルタ３３を順次縦続接続した構成である。つまり、第１および第２の周波数振幅変換部２０，３０は構成が共通となっている。   The first frequency / amplitude conversion unit 20 has a configuration in which a pre-pass low-pass filter 21, a full-wave rectifier circuit 22, and a post-pass low-pass filter 23 are connected in cascade. The full-wave rectifier circuit 32 and the post-pass low-pass filter 33 are connected in cascade. That is, the first and second frequency / amplitude converters 20 and 30 have a common configuration.

図２に前置ローパスフィルタ２１，３１の周波数特性を示す。周波数帯域の設定は、ＦＳＫ変調信号Ｓ１０の中心周波数ｆ０及び上側周波数ｆＨ、下側周波数ｆＬが減衰域となるようにする。これにより、前置ローパスフィルタ２１，３１からは、周波数の変化が振幅の変化となって出力される。この変化の割合は、減衰域の傾きである「−２０×フィルタ次数［ｄＢ／ｄｅｃ］」で設定される。   FIG. 2 shows frequency characteristics of the pre-pass low-pass filters 21 and 31. The frequency band is set such that the center frequency f0, the upper frequency fH, and the lower frequency fL of the FSK modulated signal S10 are in the attenuation region. Thereby, from the pre-pass low-pass filters 21 and 31, a change in frequency is output as a change in amplitude. The rate of this change is set by “−20 × filter order [dB / dec]”, which is the slope of the attenuation region.

以下、図３Ａ（ａ）〜（ｅ）、図３Ｂ（ｆ）〜（ｈ）に示す縦軸が電圧値、横軸が時間の時間応答波形を用いて、動作説明を行う。前置ローパスフィルタ２１には、送信側から受信した図３Ａ（ａ）に示すＦＳＫ変調信号Ｓ１０が入力されることから、前置ローパスフィルタ２１の出力信号Ｓ１１は図３Ａ（ｂ）に示す波形となり、全波整流回路２２の出力信号Ｓ１２は図３Ａ（ｃ）に示す波形となる。同様に、前置ローパスフィルタ３１には、送信側から受信したＦＳＫ変調信号Ｓ１０を元に作成しあるいは受信回路内部で発生させた図３Ａ（ｄ）に示すＦＳＫ中心周波数信号Ｓ２０が入力されることから、前置ローパスフィルタ３１の出力信号Ｓ２１は図３Ａ（ｅ）に示す波形となり、全波整流回路３２の出力信号Ｓ２２は図３Ｂ（ｆ）に示す波形となる。   Hereinafter, the operation will be described using a time response waveform in which the vertical axis shown in FIGS. 3A (a) to 3 (e) and FIGS. 3B (f) to (h) is a voltage value and the horizontal axis is time. Since the FSK modulation signal S10 shown in FIG. 3A (a) received from the transmission side is input to the pre-low pass filter 21, the output signal S11 of the pre-low pass filter 21 has a waveform shown in FIG. 3A (b). The output signal S12 of the full-wave rectifier circuit 22 has the waveform shown in FIG. 3A (c). Similarly, the FSK center frequency signal S20 shown in FIG. 3A (d) generated based on the FSK modulation signal S10 received from the transmission side or generated inside the reception circuit is input to the pre-low pass filter 31. Therefore, the output signal S21 of the pre-pass filter 31 has the waveform shown in FIG. 3A (e), and the output signal S22 of the full-wave rectifier circuit 32 has the waveform shown in FIG. 3B (f).

図３Ｂ（ｇ）は後置ローパスフィルタ２３、３３の出力信号Ｓ１３，Ｓ２３の波形を示し、全波整流回路２２，３２の出力信号Ｓ１２，Ｓ２２から入力信号の基本周波数成分より大きな周波数成分が減衰された波形を示す。ここで、後置ローパスフィルタ２３の出力信号Ｓ１３は、ＦＳＫ変調信号Ｓ１０の上側周波数ｆＨと下側周波数ｆＬに応じて電圧値が変化しており、その変化の速度はＦＳＫ変調信号Ｓ１０の変調レートとなる。一方、後置ローパスフィルタ３３の出力信号Ｓ２３は、ＦＳＫ中心周波数信号Ｓ２０が無変調で且つ基本周波数がＦＳＫ変調信号Ｓ１０の中心周波数であることから、後置ローパスフィルタ２３の出力信号Ｓ１３の電圧振幅の中心値となる。   FIG. 3B (g) shows the waveforms of the output signals S13 and S23 of the post-pass low-pass filters 23 and 33, and a frequency component larger than the fundamental frequency component of the input signal is attenuated from the output signals S12 and S22 of the full-wave rectifier circuits 22 and 32. The resulting waveform is shown. Here, the output signal S13 of the post-pass low-pass filter 23 changes in voltage value according to the upper frequency fH and the lower frequency fL of the FSK modulation signal S10, and the speed of the change is the modulation rate of the FSK modulation signal S10. It becomes. On the other hand, the output signal S23 of the post-low-pass filter 33 has the voltage amplitude of the output signal S13 of the post-low-pass filter 23 because the FSK center frequency signal S20 is unmodulated and the fundamental frequency is the center frequency of the FSK-modulated signal S10. The center value of.

よって、図３Ｂ（ｇ）の両出力信号Ｓ１３，Ｓ２３を比較器４０で符号判定すれば、図３Ｂ（ｈ）に示すように、符号「１」の期間と符号「０」の期間でのバランスがとれたデューティ比が５０％のＦＳＫ復調信号Ｓ３０が得られる。   Therefore, if both the output signals S13 and S23 of FIG. 3B (g) are subjected to code determination by the comparator 40, the balance between the period of the code “1” and the period of the code “0” as shown in FIG. 3B (h). An FSK demodulated signal S30 with a duty ratio of 50% is obtained.

本実施例では、出力信号を比較器４０に入力する第１および第２の周波数振幅変換部２０，３０の構成が共通であるので、両者間の相対誤差を所定値以下に確保できれば、環境変動や製造バラツキなどの様々な変動があっても、比較器４０での安定な符号判定動作を実現できる。適用例として半導体集積回路でこれらを構成する場合には、一般に相対誤差は１％以下であり、調整用の外部部品も不要となる。   In this embodiment, since the first and second frequency / amplitude converters 20 and 30 for inputting the output signal to the comparator 40 have the same configuration, if the relative error between the two can be kept below a predetermined value, the environmental fluctuation Even if there are various variations such as variations in manufacturing and manufacturing, a stable code determination operation in the comparator 40 can be realized. As an application example, when these are constituted by a semiconductor integrated circuit, the relative error is generally 1% or less, and no external component for adjustment is required.

＜第２の実施例＞
図４は、本発明の第２の実施例のＦＳＫ復調器１０Ａの構成を示すブロック図である。本実施例のＦＳＫ復調器１０Ａは、図１で説明した第１および第２の周波数振幅変換部２０，３０における全波整流回路２２，３２を二乗回路２４，３４に置き換えて、第１および第２の周波数振幅変換部２０Ａ，３０Ａを構成したものである。二乗回路２４，３４は入力信号を二乗するので、その出力は常に正の値となることから、図３Ａ（ｃ）、図３Ｂ（ｆ）に示した全波整流回路２２，３２の出力信号Ｓ１２，Ｓ２２と全く同一の波形となり、第１の実施例のＦＳＫ復調器１０と同様の作用効果がある。 <Second embodiment>
FIG. 4 is a block diagram showing the configuration of the FSK demodulator 10A according to the second embodiment of the present invention. The FSK demodulator 10A of the present embodiment replaces the full-wave rectifier circuits 22 and 32 in the first and second frequency / amplitude converters 20 and 30 described in FIG. 2 frequency / amplitude converters 20A and 30A. Since the squaring circuits 24 and 34 square the input signal, the output is always a positive value. Therefore, the output signals S12 of the full-wave rectifier circuits 22 and 32 shown in FIGS. 3A (c) and 3B (f). , S22 have exactly the same waveforms and have the same effects as the FSK demodulator 10 of the first embodiment.

＜第３の実施例＞
図５は、本発明の第３の実施例のＦＳＫ復調器１０Ｂの構成を示すブロック図である。本実施例のＦＳＫ復調器１０Ｂは、図１で説明した第１および第２の周波数振幅変換部２０，３０における全波整流回路２２，３２を、乗算器２５と移相器２６、乗算器３５と移相器３６に置き換えて、第１および第２の周波数振幅変換部２０Ｂ，３０Ｂを構成したものである。移相器２６，３６は、前置ローパスフィルタ２１，３１の出力信号の周波数に応じて移相量が変化し且つＦＳＫ変調信号Ｓ１０の中心周波数での該移相量が９０度の奇数倍となる移相器である。 <Third embodiment>
FIG. 5 is a block diagram showing the configuration of the FSK demodulator 10B according to the third embodiment of the present invention. The FSK demodulator 10B according to the present embodiment includes full-wave rectifier circuits 22 and 32 in the first and second frequency / amplitude converters 20 and 30 described with reference to FIG. 1, a multiplier 25, a phase shifter 26, and a multiplier 35. In this case, the first and second frequency / amplitude converters 20B and 30B are configured in place of the phase shifter 36. The phase shifters 26 and 36 change the amount of phase shift according to the frequency of the output signals of the pre-pass filters 21 and 31, and the amount of phase shift at the center frequency of the FSK modulation signal S10 is an odd multiple of 90 degrees. It is a phase shifter.

ここで、図５のＦＳＫ復調器１０Ｂにおける前置ローパスフィルタ２１、３１は、ＦＳＫ変調信号Ｓ１０及びＦＳＫ中心周波数信号Ｓ２０の基本周波数成分より大きな周波数成分が減衰される周波数特性をもつ。第１および第２の周波数振幅変換部２０Ｂ，３０Ｂの動作は、背景技術で説明した従来のクァドラチャ検波方式の回路と同一であり、図６の閾値設定器５５を第２の周波数振幅変換部３０Ｂに置き換え、ＦＳＫ中心周波数信号Ｓ２０を入力したものとなっている。これにより、後置ローパスフィルタ３３の出力信号は、後置ローパスフィルタ２３の出力電圧振幅の中心値となり、比較器４０で正常な符号判定が行われる。本実施例でも、第１の実施例と同様な作用効果がある。   Here, the pre-pass low-pass filters 21 and 31 in the FSK demodulator 10B in FIG. 5 have frequency characteristics in which frequency components larger than the fundamental frequency components of the FSK modulation signal S10 and the FSK center frequency signal S20 are attenuated. The operations of the first and second frequency amplitude converters 20B and 30B are the same as those of the conventional quadrature detection circuit described in the background art, and the threshold value setter 55 of FIG. 6 is replaced with the second frequency amplitude converter 30B. The FSK center frequency signal S20 is input. As a result, the output signal of the post-low-pass filter 33 becomes the center value of the output voltage amplitude of the post-low-pass filter 23, and the normal sign determination is performed by the comparator 40. This embodiment also has the same operational effects as the first embodiment.

本発明の第１の実施例のＦＳＫ復調器の構成を示すブロック図である。It is a block diagram which shows the structure of the FSK demodulator of the 1st Example of this invention. 図１のＦＳＫ復調器の前置ローパスフィルタ２１，３１の周波数特性図である。FIG. 3 is a frequency characteristic diagram of pre-pass low-pass filters 21 and 31 of the FSK demodulator of FIG. 1. 図１のＦＳＫ復調器の各部の信号波形図である。It is a signal waveform diagram of each part of the FSK demodulator of FIG. 図１のＦＳＫ復調器の各部の信号波形図である。It is a signal waveform diagram of each part of the FSK demodulator of FIG. 本発明の第２の実施例のＦＳＫ復調器の構成を示すブロック図である。It is a block diagram which shows the structure of the FSK demodulator of the 2nd Example of this invention. 本発明の第３の実施例のＦＳＫ復調器の構成を示すブロック図である。It is a block diagram which shows the structure of the FSK demodulator of the 3rd Example of this invention. 従来のクァドラチャ方式のＦＳＫ復調器の構成を示すブロック図である。It is a block diagram which shows the structure of the conventional quadrature-type FSK demodulator.

符号の説明Explanation of symbols

Ｓ１０：ＦＳＫ変調信号、Ｓ２０：ＦＳＫ中心周波数信号、Ｓ３０：ＦＳＫ復調信号
１０，１０Ａ，１０Ｂ：ＦＳＫ復調器
２０，２０Ａ，２０Ｂ：第１の周波数振幅変換部、２１：前置ローパスフィルタ、２２：全波整流回路、２３：後置ローパスフィルタ、２４：二乗回路、２５：乗算器、２６：移相器
３０，３０Ａ，３０Ｂ：第２の周波数振幅変換部、３１：前置ローパスフィルタ、３２：全波整流回路、３３：後置ローパスフィルタ、３４：二乗回路、３５：乗算器、３６：移相器
４０：比較器
５０：ＦＳＫ復調器、５１：前置ローパスフィルタ、５２：乗算器、５３：移相器、５４：後置ローパスフィルタ、５５：閾値設定器、５６：比較器 S10: FSK modulated signal, S20: FSK center frequency signal, S30: FSK demodulated signal 10, 10A, 10B: FSK demodulator 20, 20A, 20B: first frequency amplitude converter, 21: pre-low pass filter, 22: Full-wave rectifier circuit, 23: Post-pass low-pass filter, 24: Square circuit, 25: Multiplier, 26: Phase shifter 30, 30A, 30B: Second frequency amplitude converter, 31: Pre-pass low-pass filter, 32: Full-wave rectifier circuit 33: Post-pass low-pass filter 34: Square circuit 35: Multiplier 36: Phase shifter 40: Comparator 50: FSK demodulator 51: Pre-pass low-pass filter 52: Multiplier 53 : Phase shifter, 54: post-pass low-pass filter, 55: threshold setting device, 56: comparator

Claims (3)

ＦＳＫ変調信号を入力し周波数に応じた振幅信号に変換する第１の周波数振幅変換部と、前記ＦＳＫ変調信号の中心周波数信号を入力し前記第１の周波数振幅変換部と構成が共通の第２の周波数振幅変換部とを備え、前記第１の周波数振幅変換部の出力信号振幅と前記第２の周波数振幅変換部の出力信号振幅とを比較することにより符号判定を行うＦＳＫ復調器において、
前記第１および第２の周波数振幅変換部を、前記中心周波数が減衰域にあるような周波数特性をもつ前置ローパスフィルタと、該前置ローパスフィルタの出力の交流成分を全波整流する全波整流回路と、該全波整流回路の出力から前記中心周波数より高い周波数成分を減衰させる後置ローパスフィルタとから構成した、ことを特徴とするＦＳＫ復調器。 A first frequency / amplitude converter that inputs an FSK modulation signal and converts it into an amplitude signal corresponding to the frequency, and a second frequency having the same configuration as the first frequency / amplitude converter that receives the center frequency signal of the FSK modulation signal. In the FSK demodulator that performs the code determination by comparing the output signal amplitude of the first frequency amplitude conversion unit and the output signal amplitude of the second frequency amplitude conversion unit ,
The first and second frequency / amplitude converters include a pre-low-pass filter having a frequency characteristic such that the center frequency is in an attenuation region, and a full-wave rectifying the AC component of the output of the pre-low-pass filter. An FSK demodulator comprising: a rectifier circuit; and a post-pass low-pass filter that attenuates a frequency component higher than the center frequency from the output of the full-wave rectifier circuit . 請求項１に記載のＦＳＫ復調器において、
前記全波整流回路を、前記前置ローパスフィルタの出力の交流成分を二乗する二乗回路に置き換えたことを特徴とするＦＳＫ復調器。 The FSK demodulator according to claim 1, wherein
2. An FSK demodulator, wherein the full-wave rectifier circuit is replaced with a square circuit that squares an alternating current component of the output of the pre-pass low-pass filter . 請求項１に記載のＦＳＫ復調器において、
前記全波整流回路を、前記前置ローパスフィルタの出力信号の周波数に応じて移相量が変化し且つ前記ＦＳＫ変調信号の中心周波数での該移相量が９０度の奇数倍となる移相器と、該移相器の出力信号と前記前置ローパスフィルタの出力信号とを乗算し前記後置ローパスフィルタに出力する乗算器とからなる回路に置き換えたことを特徴とするＦＳＫ復調器。 The FSK demodulator according to claim 1 , wherein
The full-wave rectifier circuit is configured so that the amount of phase shift changes according to the frequency of the output signal of the pre-low pass filter and the amount of phase shift at the center frequency of the FSK modulation signal is an odd multiple of 90 degrees. The FSK demodulator is replaced with a circuit that includes a multiplier and a multiplier that multiplies the output signal of the phase shifter and the output signal of the pre-low-pass filter and outputs to the post-low-pass filter .
JP2008154531A 2008-06-12 2008-06-12 FSK demodulator Expired - Fee Related JP5033065B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2008154531A JP5033065B2 (en) 2008-06-12 2008-06-12 FSK demodulator

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2008154531A JP5033065B2 (en) 2008-06-12 2008-06-12 FSK demodulator

Publications (2)

Publication Number Publication Date
JP2009302862A JP2009302862A (en) 2009-12-24
JP5033065B2 true JP5033065B2 (en) 2012-09-26

Family

ID=41549309

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2008154531A Expired - Fee Related JP5033065B2 (en) 2008-06-12 2008-06-12 FSK demodulator

Country Status (1)

Country Link
JP (1) JP5033065B2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024041387A1 (en) * 2022-08-23 2024-02-29 华为技术有限公司 Signal processing circuit, signal processing method and electronic device

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6253551A (en) * 1985-09-03 1987-03-09 Hitachi Shonan Denshi Kk Demodulation circuit for digital data subjected to frequency modulation
JPH0193950A (en) * 1987-10-06 1989-04-12 Nippon Telegr & Teleph Corp <Ntt> Digital fm detecting and demodulating system
JP3022858B1 (en) * 1998-12-15 2000-03-21 日本電気アイシーマイコンシステム株式会社 FSK signal demodulation circuit and FSK signal demodulation method

Also Published As

Publication number Publication date
JP2009302862A (en) 2009-12-24

Similar Documents

Publication Publication Date Title
JP4495210B2 (en) Amplitude error compensator and orthogonality error compensator
US4788696A (en) Decision timing control circuit
US6310513B1 (en) Demodulator and demodulation method for demodulating quadrature modulation signals
US9490858B2 (en) Transmitter capable of reducing local oscillation leakage and in-phase/quadrature-phase (I/Q) mismatch and adjusting methods thereof
US5398002A (en) Automatic frequency control system by quadrature-phase in frequency or phase demodulating system
US5128966A (en) System for demodulating frequency- or phase-modulated signals by quadrature-phase
JP5033065B2 (en) FSK demodulator
JPS5980048A (en) Automatic phase control circuit
JP4312705B2 (en) Quadrature demodulation error compensation method and quadrature demodulation error compensation circuit
US6483883B1 (en) Automatic gain control type demodulation apparatus having single automatic gain control circuit
US20060111073A1 (en) Demodulator of frequency modulated signals, and demodulating method of frequency modulated signals
JP3029394B2 (en) FSK demodulator
JP4641927B2 (en) FSK demodulation circuit
JP2965593B2 (en) Demodulator and data transmission system
US10256889B2 (en) Method and device for conditioning a radio data signal for a broadcast receiver
JP3697675B2 (en) Center error detection circuit for FSK receiver
JP4324595B2 (en) Digital modulation signal demodulator
JP7158344B2 (en) demodulator
KR900004407B1 (en) Auto frequency control method in frequency and phase demodulation system by quadri-phase
JPH06224960A (en) Method and equipment for demodulating digital phase modulation signal
US6573782B2 (en) Sigma delta FM ratio detector
JPH07107126A (en) Frequency shift keying data demodulator
JPH08149174A (en) Phase comparison method
JP5767170B2 (en) FSK demodulator
JP5801764B2 (en) FSK demodulator

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20110405

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20120423

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20120508

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20120606

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20120622

A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20120629

R150 Certificate of patent or registration of utility model

Ref document number: 5033065

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20150706

Year of fee payment: 3

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

LAPS Cancellation because of no payment of annual fees