JPH01112866A - Frequency modulation circuit - Google Patents
Frequency modulation circuitInfo
- Publication number
- JPH01112866A JPH01112866A JP62269840A JP26984087A JPH01112866A JP H01112866 A JPH01112866 A JP H01112866A JP 62269840 A JP62269840 A JP 62269840A JP 26984087 A JP26984087 A JP 26984087A JP H01112866 A JPH01112866 A JP H01112866A
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- signal
- rom
- counter
- digital
- 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
- 230000005540 biological transmission Effects 0.000 claims abstract description 8
- 101100087530 Caenorhabditis elegans rom-1 gene Proteins 0.000 abstract description 3
- 101100305983 Mus musculus Rom1 gene Proteins 0.000 abstract description 3
- 238000004364 calculation method Methods 0.000 abstract description 2
- 230000003044 adaptive effect Effects 0.000 abstract 1
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 101001106432 Homo sapiens Rod outer segment membrane protein 1 Proteins 0.000 description 1
- 102100021424 Rod outer segment membrane protein 1 Human genes 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
Landscapes
- Facsimile Image Signal Circuits (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は周波数変調回路に係り、特に中間調を含むディ
ジタル画像信号の周波数変調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 a frequency modulation circuit, and particularly to a frequency modulation circuit for digital image signals including halftones.
従来、この種の周波数変調回路は、ディジタル画像信号
をディジタル−アナログ（Ｄ−Ａ ）変換回路でアナロ
グ信号に変換した後、電圧・周波数変換回路によシアナ
ログ信号の電圧に対応した周波数に変換して周波数変調
を行っていた。Conventionally, this type of frequency modulation circuit converts a digital image signal into an analog signal using a digital-to-analog (D-A) conversion circuit, and then converts it into a frequency corresponding to the voltage of the analog signal using a voltage/frequency conversion circuit. frequency modulation.
、 〔発明が解決しようとする問題点〕上述した従来の
周波数変調回路は、ディジタル画像信号をＤ−Ａ変換回
路によシアナログ信号に変換しているので、信号処理の
過程でアナログ信号の補正が必要になるという問題点が
あった。[Problems to be Solved by the Invention] The conventional frequency modulation circuit described above converts a digital image signal into an analog signal using a D-A conversion circuit, so it is necessary to correct the analog signal in the process of signal processing. The problem was that it required
本発明の周波数変調回路は、予め中間調を含むディジタ
ル画像信号に対応した分周値を格納するＲＯＭと、上記
分局値によシ基準周波数信号を分周するカウンタと、こ
のカウンタからの分周された基準周波数信号を伝送帯域
内信号に変換する分局器と、上記伝送帯域内信号から高
調波成分を除去しアナログ画像信号を出力する低域フィ
ルタとを含んで構成されるものである。The frequency modulation circuit of the present invention includes a ROM that stores in advance a frequency division value corresponding to a digital image signal including halftones, a counter that divides the frequency of a reference frequency signal according to the division value, and a frequency modulation circuit that performs frequency division from this counter. The system includes a splitter that converts the reference frequency signal into a transmission band signal, and a low-pass filter that removes harmonic components from the transmission band signal and outputs an analog image signal.
本発明においては、ディジタル画像信号のディジタル値
に対応した基準周波数信号の分局比をＲＯＭに格納して
おくことにより、中間調を含むディジタル画像信号を直
接周波数変調する。In the present invention, a digital image signal including halftones is directly frequency-modulated by storing a division ratio of a reference frequency signal corresponding to a digital value of a digital image signal in a ROM.
以下、図面に基づき本発明の実施例を詳細に説−明する
。Hereinafter, embodiments of the present invention will be described in detail based on the drawings.
図は本発明の一実施例を示すブロック図である。The figure is a block diagram showing one embodiment of the present invention.
図において、１は予め中間調を含んだディジタル画像信
号Ｙに対応した分局値ＣＴを格納するＲＯＭ１２は基準
周波数信号Ｆｓを発生する発振器、３は分局値ＣＴによ
り基準周波数信号Ｆ８を分周するカウンタ、４はこのカ
ウンタ３からの分周された基準周波数信号を伝送帯域内
信号に変換する分局器、５はこの分局器４によって得ら
れた伝送帯域内信号から高調波成分を除去しアナログ画
像信号Ｆａを出力する低域フィルタである。In the figure, 1 is an oscillator that stores a division value CT corresponding to a digital image signal Y that includes halftones, and a ROM 12 is an oscillator that generates a reference frequency signal Fs.3 is a counter that divides the reference frequency signal F8 by the division value CT. , 4 is a divider that converts the frequency-divided reference frequency signal from this counter 3 into a transmission band signal, and 5 is a divider that removes harmonic components from the transmission band signal obtained by this divider 4 to produce an analog image signal. This is a low-pass filter that outputs Fa.
つぎにこの図に示す実施例の動作を説明する。Next, the operation of the embodiment shown in this figure will be explained.
まず、ディジタル画像信号ＹはＲＯＭ１に供給される。First, the digital image signal Y is supplied to the ROM1.
このＲＯＭＩＫは、予め下記の計算式によ）求められた
データがディジタル画像信号Ｙのそれぞれのディジタル
値ｙに対応して格納される。In this ROMIK, data obtained in advance (using the following calculation formula) is stored corresponding to each digital value y of the digital image signal Y.
そして、ファクシミリ信号の周波数変調は黒に対してｆ
”” １５．００Ｈｚ 、白に対してｆ＝２３００Ｈ
ｚの周波数が与えられるが、いま、黒濃度に対応するデ
ィジタル値ｙが２３０．白濃度に対応するディジタル値
ｙが０であるとすると、ディジタル値ｙは式（１）で示
される。And the frequency modulation of the facsimile signal is f for black.
"" 15.00Hz, f=2300H for white
The frequency of z is given, but now the digital value y corresponding to the black density is 230. Assuming that the digital value y corresponding to white density is 0, the digital value y is expressed by equation (1).
７＝Ａ串ｆ＋Ｂ ・・・・・・ （
１）ただし、ＡおよびＢは定数である。7=A skewer f+B ・・・・・・(
1) However, A and B are constants.
したがって、白濃度および黒濃度に対して式（１）はそ
れぞれ式（２）および式（３）のように示される。Therefore, equation (1) can be expressed as equation (2) and equation (3) for white density and black density, respectively.
０＝Ａ・１５．ＯＯ＋Ｂ ・・・・・・
（２）２３０＝Ａ・２３００＋Ｂ ・
・・・・・ （３）この式（２）および式（３）から、
Ａｊ？よびＢはそれぞれ式（４）および式（５）のよう
に示される。0=A・15. OO+B・・・・・・
(2) 230=A・2300+B・
... (3) From this equation (2) and equation (3),
Aj? and B are shown as in equation (4) and equation (5), respectively.
したがって、式（４）および式（５）からディジタル値
ｙは式（６）のように示される。Therefore, from equations (4) and (5), the digital value y is expressed as shown in equation (6).
ここで、基準周波数信号ＦＩｌの周波数をｆｓとすると
、で、であるから、式（６）は式（７）のように示され
る。Here, if the frequency of the reference frequency signal FIl is fs, then Equation (6) can be expressed as Equation (7).
この（７）式を移項して整理すると式（８）が得られる
。If this equation (7) is rearranged by shifting terms, equation (8) is obtained.
すなわち、ディジタル値ｙに対し式（８）に示すデータ
を分局値ＣＴとしてＲＯＭ １ に格納しておく。That is, the data shown in equation (8) for the digital value y is stored in the ROM 1 as the branch value CT.
つぎに、カウンタ３は発振器２から供給される基準周波
数信号ｐｓをＨｏｎ１ から読出された分周値ＣＴで分
周して、ディジタル画像信号ＹＫ対応した周波数変調さ
れた信号を出力する。Next, the counter 3 frequency-divides the reference frequency signal ps supplied from the oscillator 2 by the frequency division value CT read from Hon1, and outputs a frequency-modulated signal corresponding to the digital image signal YK.
このカウンタ３からの信号は分局器４で伝送帯域に適合
する白に対して２３００Ｈｚ 、 黒に対して１５．
０ＯＨｚ の周波数の信号に変換され、低域フィルタ５
で不要の高調波成分が除去されて、周波数変調されたア
ナログ画像信号Ｆａ として出力される。The signal from this counter 3 is sent to a divider 4, which matches the transmission band: 2300 Hz for white and 15 Hz for black.
It is converted into a signal with a frequency of 0 Hz, and is passed through a low-pass filter 5.
Unnecessary harmonic components are removed at , and the signal is output as a frequency-modulated analog image signal Fa.
以上説明したように１本発明は、ディジタル画像信号の
ディジタル値に対応する基準周波数信号の分周比をＲＯ
Ｍ ＧＣ格納しておくことにょシ、中間調を含むディジ
タル画像信号を直接周波数変調できるので、アナログ信
号の補正を要しないという効果がある。As explained above, one aspect of the present invention is to divide the frequency division ratio of the reference frequency signal corresponding to the digital value of the digital image signal into RO
By storing the MGC, digital image signals including halftones can be directly frequency-modulated, so there is no need to correct analog signals.
図は本発明の一実施例を示すブロック図である。
１・Φ・・ＲＯＭ、２の・・・発振器、３・−・・カウ
ンタ、４・・・・分周器、５・・・・低域フィルタ。
特許出願人 日本電気株式会社
日本電気エンジニアリング株式会社The figure is a block diagram showing one embodiment of the present invention. 1... ROM, 2... oscillator, 3... counter, 4... frequency divider, 5... low pass filter. Patent applicant: NEC Corporation NEC Engineering Co., Ltd.
Claims (1)
を格納するＲＯＭと、前記分周値により基準周波数信号
を分周するカウンタと、このカウンタからの分周された
基準周波数信号を伝送帯域内信号に変換する分周器と、
前記伝送帯域内信号から高調波成分を除去しアナログ画
像信号を出力する低域フィルタとを含むことを特徴とす
る周波数変調回路。A ROM that stores in advance a frequency division value corresponding to a digital image signal including halftones, a counter that divides a reference frequency signal by the frequency division value, and a frequency-divided reference frequency signal from this counter within a transmission band. a frequency divider that converts it into a signal;
A frequency modulation circuit comprising: a low-pass filter that removes harmonic components from the transmission band signal and outputs an analog image signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62269840A JPH01112866A (en) | 1987-10-26 | 1987-10-26 | Frequency modulation circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62269840A JPH01112866A (en) | 1987-10-26 | 1987-10-26 | Frequency modulation circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01112866A true JPH01112866A (en) | 1989-05-01 |
Family
ID=17477918
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62269840A Pending JPH01112866A (en) | 1987-10-26 | 1987-10-26 | Frequency modulation circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01112866A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02301266A (en) * | 1989-05-15 | 1990-12-13 | Nec Corp | Sampling clock generating circuit |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61131902A (en) * | 1984-11-30 | 1986-06-19 | Sony Corp | Frequency modulator |
| JPS61131901A (en) * | 1984-11-30 | 1986-06-19 | Sony Corp | Digital frequency modulator |
-
1987
- 1987-10-26 JP JP62269840A patent/JPH01112866A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61131902A (en) * | 1984-11-30 | 1986-06-19 | Sony Corp | Frequency modulator |
| JPS61131901A (en) * | 1984-11-30 | 1986-06-19 | Sony Corp | Digital frequency modulator |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02301266A (en) * | 1989-05-15 | 1990-12-13 | Nec Corp | Sampling clock generating circuit |
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