JPH0722372B2 - Modulation circuit of magnetic recording / reproducing apparatus - Google Patents
Modulation circuit of magnetic recording / reproducing apparatusInfo
- Publication number
- JPH0722372B2 JPH0722372B2 JP61277087A JP27708786A JPH0722372B2 JP H0722372 B2 JPH0722372 B2 JP H0722372B2 JP 61277087 A JP61277087 A JP 61277087A JP 27708786 A JP27708786 A JP 27708786A JP H0722372 B2 JPH0722372 B2 JP H0722372B2
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- magnetic recording
- recording
- modulation
- reproducing apparatus
- 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 - Lifetime
Links
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 description 5
- 238000001228 spectrum Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
Landscapes
- Television Signal Processing For Recording (AREA)
Description
【発明の詳細な説明】 （イ） 産業上の利用分野 本発明は、映像信号を磁気テープ等の磁気記録媒体に周
波数変調して記録する磁気記録再生装置の変調回路に関
する。TECHNICAL FIELD The present invention relates to a modulation circuit of a magnetic recording / reproducing apparatus for frequency-modulating and recording a video signal on a magnetic recording medium such as a magnetic tape.
（ロ） 従来の技術 一般に家庭用の磁気記録再生装置（以下VTRと称する）
における輝度信号の記録時、変調指数の低い周波数変調
（以下FM変調と称する）を行っている。その一例として
日本放送出版協会発行原正和著の「ホームビデオ」P114
〜P119があげられる。(B) Conventional technology Magnetic recording / reproducing apparatus for home use (hereinafter referred to as VTR)
At the time of recording the luminance signal in, the frequency modulation with a low modulation index (hereinafter referred to as FM modulation) is performed. As an example, “Home Video” by Masakazu Hara published by Japan Broadcast Publishing Association P114
~ P119 is given.
この場合第３図に示す特性のように変調波の帯域が広い
ため、本来のFM波は非常に広い帯域を持つ。ところが前
記磁気テープ等への記録又は再生の過程で、帯域特性が
充分でないため、用いられる搬送波周波数は信号帯域
（第３図（イ））に比べてFM波の帯域を充分カバーでき
る値に設定されていない。（第３図（ロ）） このとき周波数偏移（FMdeviation）は第３図（ハ）に
示すような周波数スペクトラムになり、周波数軸の原点
を中心に折返し、別の信号周波数のサイドバンドの如く
現われる。In this case, since the band of the modulated wave is wide as shown in the characteristic of FIG. 3, the original FM wave has a very wide band. However, since the band characteristic is not sufficient in the process of recording or reproducing on the magnetic tape, the carrier frequency used is set to a value that can sufficiently cover the FM wave band compared to the signal band (Fig. 3 (a)). It has not been. (Fig. 3 (b)) At this time, the frequency deviation (FMdeviation) becomes a frequency spectrum as shown in Fig. 3 (c), and it folds back around the origin of the frequency axis and looks like a side band of another signal frequency. Appears.
（ハ） 発明が解決しようとする問題点 従来の構成による特性のため、FM変調により生じるサイ
ドバンドのうち、実際に記録、再生に寄与するものが信
号（変調波）の周波数によっては第１のサイドバンドの
みの場合が多いが、前述の折返しに起因して、高次のサ
イドバンドの発生に伴い、再生時の映像信号に歪みとな
って現われてしまう欠点があった。(C) Problems to be solved by the invention Due to the characteristics of the conventional configuration, among the sidebands generated by FM modulation, the one that actually contributes to recording and reproduction may be the first one depending on the frequency of the signal (modulated wave). In many cases, only sidebands are used, but due to the above-mentioned folding back, there is a drawback in that a high-order sideband is generated and distortion occurs in a video signal during reproduction.
本発明は前記欠点を除去した新規な変調方式を提供する
ものである。The present invention provides a new modulation method that eliminates the above drawbacks.
（ニ） 問題点を解決するための手段 本発明は、映像信号を周波数変調し、記録再生ヘッドに
より磁気記録媒体に記録し、前記記録再生ヘッドにより
得た前記変調された信号を復調し、前記映像信号を再生
する磁気記録再生装置において、規定の周波数より高い
搬送波周波数を用いる周波数変調手段と、該変調手段の
変調出力の帯域を制限する手段と、前記変調出力の周波
数を前記規定の周波数に逓減する周波数変換手段を具備
し、一旦規定の周波数より高い搬送周波数を変調及び帯
域制限した後に前記規定の周波数に逓減し、前記記録媒
体に映像信号を記録する構成である。(D) Means for Solving the Problems The present invention relates to a method of frequency-modulating a video signal, recording it on a magnetic recording medium by a recording / reproducing head, demodulating the modulated signal obtained by the recording / reproducing head, In a magnetic recording / reproducing apparatus for reproducing a video signal, a frequency modulating means using a carrier frequency higher than a prescribed frequency, a means for limiting a band of a modulated output of the modulating means, and a frequency of the modulated output to the prescribed frequency. The frequency conversion means for decreasing the frequency is provided, and the carrier frequency higher than the specified frequency is temporarily modulated and band-limited, and then the frequency is decreased to the specified frequency, and the video signal is recorded on the recording medium.
（ホ） 作用 本発明の変調方式は、特に第２次以上の高次のサイドバ
ンドが周波数軸の原点を中心に折返しの発生を防止し得
る。(E) Operation The modulation method of the present invention can prevent the second and higher sidebands from folding back around the origin of the frequency axis.
（ヘ） 実施例 図面に従って本発明を説明すると、第１図は本発明の一
実施例を示すブロック構成図、第２図（イ）（ロ）
（ハ）は各々前記各部における信号の周波数スペクトラ
ムを示す。(F) Embodiments The present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 (a) and (b).
(C) shows the frequency spectrum of the signal in each of the above parts.
図面において、（１）は映像信号印加端子、（２）は高
周波数帯域（ハイバンド）用の高周波変調回路、（３）
はバンドパスフィルタ（以下B.P.F.と略称する）、
（４）は周波数変換回路、（５）は記録イコライザ、
（６）は記録アンプ、（７）は磁気記録再生ヘッドを示
し、前記端子（１）には輝度を含む映像信号が印加され
る。In the drawings, (1) is a video signal application terminal, (2) is a high frequency modulation circuit for a high frequency band (high band), and (3)
Is a bandpass filter (hereinafter abbreviated as BPF),
(4) is a frequency conversion circuit, (5) is a recording equalizer,
(6) shows a recording amplifier, (7) shows a magnetic recording / reproducing head, and a video signal including luminance is applied to the terminal (1).
前記構成で、周波数変調回路（２）にて発生した搬送波
（周波数fC）は、前記映像信号により周波数変調され
る。前記高周波変調回路（２）の出力の周波数スペク
トラムは第２図（イ）に示すようにfCを中心（その成分
をJ0とし、以下第１次、第２次以下のサイドバンドを各
々J1,J2,J3とする。With the above configuration, the carrier wave (frequency f C ) generated in the frequency modulation circuit (2) is frequency-modulated by the video signal. The frequency spectrum of the output of the high frequency modulation circuit (2) is centered on f C as shown in FIG. 2 (a) (the component is J 0, and the sidebands of the first order and the second order and below are J respectively. Let 1 , J 2 , J 3 .
このとき信号（変調波）の周波数を3MHzとすると、前記
＋J1はfC＋3M,＋J2はfC＋6M,＋J3はfC＋9M,−J1はfC−3
M,−J2はfC−6M,−J3はfC−9Mとなる。At this time, assuming that the frequency of the signal (modulated wave) is 3 MHz, + J 1 is f C + 3M, + J 2 is f C + 6M, + J 3 is f C + 9M, and −J 1 is f C −3.
M, −J 2 is f C −6M, −J 3 is f C −9M.
前記第２図（イ）に示すスペクトラムに示す通り、出力
は数多くのサイドバンドを持ち、搬送波の周波数fCは
下側のサイドバンドの折返しが問題とならない程度の高
い値に設定してある。As shown in the spectrum shown in FIG. 2 (a), the output has a large number of sidebands, and the carrier frequency f C is set to a high value such that folding of the lower sideband does not pose a problem.
そこで4MHzの搬送波を3MHzの信号で周波数変調した下側
波の折返しのないFM波を得ようとした場合前記出力を
B.P.F.（バンドパスフィルタ）（３）により帯域制限を
行い、前記変調回路（２）の搬送波よりも4MHz低い単一
周波数信号によって周波数変換回路（４）にて周波数変
換する。Therefore, when trying to obtain an FM wave without back-folding of the lower side, which is obtained by frequency-modulating a 4 MHz carrier with a 3 MHz signal,
Band limitation is performed by a BPF (band pass filter) (3), and frequency conversion is performed by a frequency conversion circuit (4) by a single frequency signal that is 4 MHz lower than the carrier wave of the modulation circuit (2).
前記B.P.F.（３）の出力は第２図（ロ）に示すように−
J1から＋J2までを通過させるB.P.F.特性を有している。
更に周波数交換回路（４）の出力は第２図（ハ）に示
す通り、周波数原点から−J1,J0,＋J1及び＋J2は各々1M
Hz,4MHz,7MHz,10MHzになり、記録イコライザ（５）への
入力は4MHzの搬送波で、周波数偏移1MHzのFM波である。The output of the BPF (3) is as shown in Fig. 2 (b)-
It has a BPF characteristic that passes from J 1 to + J 2 .
Further, the output of the frequency switching circuit (4) is 1M from −J 1 , J 0 , + J 1 and + J 2 from the frequency origin as shown in FIG. 2 (C).
It becomes Hz, 4MHz, 7MHz, 10MHz, and the input to the recording equalizer (5) is a carrier wave of 4MHz and an FM wave with a frequency shift of 1MHz.
従って前述の例では高周波（ハイバンド）用の変調回路
（２）が周波数偏移を規定のFM変調と同じ値としてある
ため、変調指数は一般の方式と同一であり、互換性は完
全に保たれる。Therefore, in the above example, since the modulation circuit (2) for high frequency has the same frequency deviation as the specified FM modulation, the modulation index is the same as the general method and the compatibility is completely maintained. Be drunk
（ト） 発明の効果 本発明の変調方式によれば、家庭用VTRにおいて従来の
ように高次の下側サイドバンドの折返しのないFM波が得
られ記録、再生時の信号の歪みのない改善された信号が
復調されることになる。(G) Effect of the Invention According to the modulation method of the present invention, an FM wave without a high-order lower sideband folding back can be obtained as in the conventional VTR for home use, and the signal distortion during recording and reproduction can be improved. The demodulated signal will be demodulated.
第１図は本発明の磁気記録再生装置のブロック構成図、
第２図は同装置における各部信号の周波数スペクトラム
を示す特性図、第３図は従来の同装置における特性図を
示す。 （１）……映像信号入力端子、（２）……高周波変調回
路、（３）……バンドパスフィルタ、（４）……周波数
変換回路、（５）……記録イコライザ、（６）……記録
アンプ、（７）……磁気記録再生ヘッド。FIG. 1 is a block diagram of a magnetic recording / reproducing apparatus of the present invention,
FIG. 2 is a characteristic diagram showing a frequency spectrum of each signal in the device, and FIG. 3 is a characteristic diagram in the conventional device. (1) ... video signal input terminal, (2) ... high frequency modulation circuit, (3) ... band pass filter, (4) ... frequency conversion circuit, (5) ... recording equalizer, (6) ... Recording amplifier, (7) ... Magnetic recording / playback head.
Claims (1)
により磁気記録媒体に記録し、前記記録再生ヘッドによ
り得た前記変調された信号を復調し、前記映像信号を再
生する磁気記録再生装置において、規定の周波数より高
い搬送波周波数を用いる周波数変調手段と、該変調手段
の変調出力の帯域を制限する手段と、前記変調出力の周
波数を前記規定の周波数に逓減する周波数変換手段を具
備し、一旦規定の周波数より高い搬送周波数を変調及び
帯域制限した後に前記規定の周波数に逓減し、前記磁気
記録媒体に映像信号を記録することを特徴とした磁気記
録再生装置の変調回路。1. A magnetic recording / reproducing apparatus for frequency-modulating a video signal, recording the same on a magnetic recording medium by a recording / reproducing head, demodulating the modulated signal obtained by the recording / reproducing head, and reproducing the video signal. A frequency modulation means that uses a carrier frequency higher than a specified frequency, a means for limiting the band of the modulation output of the modulation means, and a frequency conversion means for reducing the frequency of the modulation output to the specified frequency, A modulation circuit for a magnetic recording / reproducing apparatus, wherein a carrier frequency higher than a prescribed frequency is modulated and band-limited, and then gradually reduced to the prescribed frequency to record a video signal on the magnetic recording medium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61277087A JPH0722372B2 (en) | 1986-11-20 | 1986-11-20 | Modulation circuit of magnetic recording / reproducing apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61277087A JPH0722372B2 (en) | 1986-11-20 | 1986-11-20 | Modulation circuit of magnetic recording / reproducing apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63131668A JPS63131668A (en) | 1988-06-03 |
| JPH0722372B2 true JPH0722372B2 (en) | 1995-03-08 |
Family
ID=17578595
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61277087A Expired - Lifetime JPH0722372B2 (en) | 1986-11-20 | 1986-11-20 | Modulation circuit of magnetic recording / reproducing apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0722372B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4218249A1 (en) * | 1992-06-03 | 1993-12-09 | Thomson Brandt Gmbh | Video recorder timing error rectifier - smooths luminance signal and colour carrier and reduces interfering folding and modulation products |
| DE4303469B4 (en) * | 1993-02-06 | 2005-11-10 | Deutsche Thomson-Brandt Gmbh | S-VHS video recorder |
-
1986
- 1986-11-20 JP JP61277087A patent/JPH0722372B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63131668A (en) | 1988-06-03 |
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