JPS63131734A - Fm-digital conversion circuit - Google Patents
Fm-digital conversion circuitInfo
- Publication number
- JPS63131734A JPS63131734A JP61278342A JP27834286A JPS63131734A JP S63131734 A JPS63131734 A JP S63131734A JP 61278342 A JP61278342 A JP 61278342A JP 27834286 A JP27834286 A JP 27834286A JP S63131734 A JPS63131734 A JP S63131734A
- Authority
- JP
- Japan
- Prior art keywords
- output
- signal
- input
- quantizer
- vco
- 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.)
- Pending
Links
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 8
- 238000001514 detection method Methods 0.000 abstract description 2
- 230000005236 sound signal Effects 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000284 extract Substances 0.000 description 1
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
この発明はＦＭ信号をデジタル信号に変換するＦＭ−デ
ジタル変換回路に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an FM-digital conversion circuit that converts an FM signal into a digital signal.
［従来の技＃ｉ］
従来、音声信号で変調されたＦＭ信号をデジタル信号に
変換する回路として第２図に示すような構成の回路が用
いられた。第２図においてＦＭ信号はフィルター２に入
力され、フィルター２の出力にはＦＭ検波器３が接続さ
れている。そして、ＦＭ検波器３の出力にＡＤ変換器８
が接続され、ＡＤ変換器８の出力からＰＣＭ出力が得ら
れる。[Conventional Technique #i] Conventionally, a circuit having a configuration as shown in FIG. 2 has been used as a circuit for converting an FM signal modulated by an audio signal into a digital signal. In FIG. 2, the FM signal is input to a filter 2, and an FM detector 3 is connected to the output of the filter 2. Then, an AD converter 8 is connected to the output of the FM detector 3.
is connected, and a PCM output is obtained from the output of the AD converter 8.
フィルター２は入力されたＦＭ信号から不用な妨害信号
を取り除＜、ＦＭ検波器３はＦＭ信号を検波して音声信
号を復調する。そして、この復調された音声信号をＡＤ
変換器８でデジタル信号に変換することにより、ＰＣＭ
出力を得ている。The filter 2 removes unnecessary interference signals from the input FM signal, and the FM detector 3 detects the FM signal and demodulates the audio signal. Then, this demodulated audio signal is
By converting into a digital signal with converter 8, PCM
I am getting output.
［発明が解決しようとする問題点１
従来のＦＭ−デジタル変換回路は以上のように構成され
ているので、高Ｓ／Ｎ、低歪率特性を実現するためには
ＦＭ検波器３とフィルター２に高性能なものが要求され
る。特にフィルター２は妨害（８＠を取り除くために急
峻な選択特性が要求されるために、低歪率特性を得るの
は困…であった。[Problem to be solved by the invention 1 Since the conventional FM-digital conversion circuit is configured as described above, in order to achieve high S/N and low distortion characteristics, the FM detector 3 and the filter 2 are required. requires high performance. In particular, since filter 2 requires steep selection characteristics to remove interference (8@), it has been difficult to obtain low distortion characteristics.
［問題点を解決するための手段］
この発明は従来の欠点を除去するために成されたもので
、ＦＭ入力信号にＦＭ負帰還をかけながら予測符号化Ａ
Ｄ変換を行なうことにより、ＦＭ信号を低歪率、高８
、／ Ｎでデジタル信号に変換できる回路を提供するこ
とを目的としている。[Means for Solving the Problems] This invention was made in order to eliminate the drawbacks of the conventional method.
By performing D conversion, the FM signal has a low distortion rate and a high
, /N to provide a circuit that can convert the signal into a digital signal.
［発明の実施例コ
第１図に示す本発明の実施例において、ＦＭ入力信号は
ミキサー１の片側入力に入力される。ミキサー１の出力
にはフィルター２が接続され、フィルター２の出力には
ＦＭ検波器３が接続されている。ＦＭ検波器３の出力に
は量子化器４が接続され、量子化器４の出力から、ＤＰ
ＣＭ出力を得るとともに量子化器４の出力は予測器７に
接続される。予測器７の出力はＤＡ変換器６に入力され
、また予測器７の出力からＰＣＭ出力が得られる。[Embodiment of the Invention] In the embodiment of the invention shown in FIG. 1, the FM input signal is input to one side input of the mixer 1. A filter 2 is connected to the output of the mixer 1, and an FM detector 3 is connected to the output of the filter 2. A quantizer 4 is connected to the output of the FM detector 3, and from the output of the quantizer 4, DP
While obtaining the CM output, the output of the quantizer 4 is connected to the predictor 7. The output of the predictor 7 is input to the DA converter 6, and a PCM output is obtained from the output of the predictor 7.
ＤＡ変換器６の出力はＶＣＯ５に接続され、ＶＣＯ５の
出力がミキサー１の片側入力に接続されることによって
、この回路はいわゆるＦＭ負帰還ループを構成している
。The output of the DA converter 6 is connected to the VCO 5, and the output of the VCO 5 is connected to one side input of the mixer 1, so that this circuit constitutes a so-called FM negative feedback loop.
次にこの発明の動作について説明する。ミキサー１に入
力されたＦＭ信号はＶＣＯ５の出力とかけ算される。そ
して、フィルター２によってそれぞれの差の周波数を取
り出す。入力ＦＭ信号の周波数を論、ＶＣＯ５の周波数
をｒ２とすれば、ＦＭ検波器３の入力信号の周波数は（
ｆｌ ｆ２）となる。Next, the operation of this invention will be explained. The FM signal input to the mixer 1 is multiplied by the output of the VCO 5. Then, the filter 2 extracts the frequency of each difference. Letting the frequency of the input FM signal be R2, and the frequency of the VCO 5 to be r2, the frequency of the input signal to the FM detector 3 is (
fl f2).
第１図の回路はＦＭ負１歴遠ループとして動作し、ＶＣ
Ｏ５の出力は入力ＦＭ信号にトラッキングするため、（
ｆｌ ｆ２）の信号はトラッキングの誤差信号となる。The circuit in Figure 1 operates as an FM negative 1-cycle loop, and the VC
Since the output of O5 tracks the input FM signal, (
The signal fl f2) becomes a tracking error signal.
ＦＭ検波器３はこの誤差信号をＦＭ検波する。量子化器
４はこの誤差信号（あるいは差分＠＠）を量子化するの
であるが、その童子化ビットは少なくて良く、１ピツト
の量子化器であっても良い。この量子化器４の出力から
ＤＰＣ〜１出力が得られる。量子化器４の出力は予測器
７に入力される。予測器７では量子化器４の出力をデジ
タル的に積分することで、予測器としての動作をする。The FM detector 3 performs FM detection on this error signal. The quantizer 4 quantizes this error signal (or difference @@), but the number of doji conversion bits may be small, and it may be a 1-pit quantizer. DPC~1 output is obtained from the output of this quantizer 4. The output of the quantizer 4 is input to the predictor 7. The predictor 7 operates as a predictor by digitally integrating the output of the quantizer 4.
予測器７の出力は予測信号出力となり、ＰＣＭ出力とし
て用いることができる。予測器７の出力はＤＡ変換器６
によってアナログ信号に変換され、その信号でＶＣＯ５
を制御している。The output of the predictor 7 becomes a predicted signal output, which can be used as a PCM output. The output of the predictor 7 is sent to the DA converter 6
is converted to an analog signal by
is controlled.
このＶＣＯ５の出力はミキサー１に入力され、入力ＦＭ
信号とかけ算される。The output of this VCO5 is input to mixer 1, and the input FM
Multiplied by the signal.
なお上記実施例では、予測器を積分器として用いたがこ
れは予測動作を行なうならば他の構成であっても良い。In the above embodiment, the predictor is used as an integrator, but other configurations may be used as long as a predictive operation is performed.
［発明の効果］
以上のように、この発明によればフィルターとＦＭ検波
器には、入力ＦＭ信号とＶＣＯの出力である予測信号と
の差の信号しか入力されないため、フィルターによる歪
の発生も少なくなり、負帰還効果によって歪、Ｓ／Ｎも
改善される。またＦＭ信号から簡単な＠成でＤ Ｐ Ｃ
Ｍ出力及びＰＣＭ出力を取り出すことができる。またこ
の発明はＦ〜１変調された信号を高速にＡＤ変換する必
要性がある場合に特に有効である。[Effects of the Invention] As described above, according to the present invention, only the signal of the difference between the input FM signal and the predicted signal that is the output of the VCO is input to the filter and the FM detector, so that distortion caused by the filter is also prevented. The distortion and S/N ratio are also improved due to the negative feedback effect. Also, DPC can be easily created from FM signal.
M output and PCM output can be taken out. Further, the present invention is particularly effective when it is necessary to AD convert an F~1 modulated signal at high speed.
第１図は本発明に係るＦＭ−デジタル変換回路の実施例
を示す図、第２図は従来例を示す図である。
１・・・・・・ミキサー
２・・・・・・フィルター
３・・・・・・ＦＭ検波器
４・・・・・・量子化器
５・・・・・・ＶＣＯ
６・・・・・・ＤＡＣ
７・・・・・・予測器（積分器）
８・・・・・・ＡＤ変換器FIG. 1 is a diagram showing an embodiment of an FM-digital conversion circuit according to the present invention, and FIG. 2 is a diagram showing a conventional example. 1... Mixer 2... Filter 3... FM detector 4... Quantizer 5... VCO 6...・DAC 7...Predictor (integrator) 8...AD converter
Claims (1)
回路の後段に接続されたフィルター回路と、該フィルタ
ー回路の出力を検波するＦＭ検波器と、該ＦＭ検波器の
出力を量子化する量子化器と、該量子化器の後段に接続
された予測器と、該予測器の出力をアナログ信号に変換
するＤＡ変換器と、該ＤＡ変換器の出力で制御されるＶ
ＣＯ回路とを備え、前記ＶＣＯ回路の出力を前記ミキサ
ー回路に入力することによってＦＭ負帰還ループを構成
し、ＦＭ信号をＰＣＭ信号に変換することを特徴とする
ＦＭ−デジタル変換回路。A mixer circuit that converts the frequency of an FM signal, a filter circuit connected to the rear stage of the mixer circuit, an FM detector that detects the output of the filter circuit, and a quantizer that quantizes the output of the FM detector. , a predictor connected after the quantizer, a DA converter that converts the output of the predictor into an analog signal, and a V controlled by the output of the DA converter.
CO circuit, an FM negative feedback loop is configured by inputting the output of the VCO circuit to the mixer circuit, and the FM-digital conversion circuit is characterized in that the FM signal is converted into a PCM signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61278342A JPS63131734A (en) | 1986-11-21 | 1986-11-21 | Fm-digital conversion circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61278342A JPS63131734A (en) | 1986-11-21 | 1986-11-21 | Fm-digital conversion circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63131734A true JPS63131734A (en) | 1988-06-03 |
Family
ID=17595994
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61278342A Pending JPS63131734A (en) | 1986-11-21 | 1986-11-21 | Fm-digital conversion circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63131734A (en) |
-
1986
- 1986-11-21 JP JP61278342A patent/JPS63131734A/en active Pending
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