JPH0150997B2 - - Google Patents

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Publication number
JPH0150997B2
JPH0150997B2 JP10425782A JP10425782A JPH0150997B2 JP H0150997 B2 JPH0150997 B2 JP H0150997B2 JP 10425782 A JP10425782 A JP 10425782A JP 10425782 A JP10425782 A JP 10425782A JP H0150997 B2 JPH0150997 B2 JP H0150997B2
Authority
JP
Japan
Prior art keywords
bit
code word
codeword
bits
magnetization reversal
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
Application number
JP10425782A
Other languages
Japanese (ja)
Other versions
JPS58220214A (en
Inventor
Masatoshi Shinho
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.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial 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 Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP10425782A priority Critical patent/JPS58220214A/en
Publication of JPS58220214A publication Critical patent/JPS58220214A/en
Publication of JPH0150997B2 publication Critical patent/JPH0150997B2/ja
Granted legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/14—Digital recording or reproducing using self-clocking codes
    • G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
    • G11B20/1423—Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code
    • G11B20/1426—Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code conversion to or from block codes or representations thereof

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Signal Processing For Digital Recording And Reproducing (AREA)
  • Dc Digital Transmission (AREA)

Description

【発明の詳細な説明】 本発明はデイジタル変調方法、特にデータビツ
ト４ビツトを符号語８ビツトに変換する４―８変
換方式にもとずくデイジタル変調方法に関するも
のである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital modulation method, and more particularly to a digital modulation method based on a 4-8 conversion method for converting 4 data bits into an 8-bit code word.

一般にデイジタル磁気記録は、多量の情報を経
済的に記録でき、それを長的にかつ安定に保存で
きるなどの特徴をもつている。そのための情報信
号の変調方式としてはRZ（Retrn to Zero）、RB
（Return to Bias）、NRZ（Non―Return to
Zero）、NRZI（Non―Retun to Zero Ｉ）、FM
（Frequency Modulation）、PE（Phase
Encoding）、MFM（Modified Frequency
Modulation）、M2FM（Modified MFM）など各
種提案されている。一方、最近ではこれら以外の
新しい変調方式も各種提案されている。例えば、
４／５MNRZI（Modified Non―Return to Zero
Ｉ）、3PM（３ Position Modulation）、ZM
（Zero Modulation）などである。さらに最近で
は高密度化が進み上記以外の新しい変調方式も考
えられているが、デイジタル磁気記録においては
検出窓幅TW、最小磁化反転間隔Tnio、あるいは
線ビツト密度の最高磁化反転密度に対する比DR
（Devsity Ratio）の大きな変調方式が望ましい
とされている。又、高密度化の容易さを最小磁化
反転間隔Tnioと検出窓幅TWとの積で表わすこと
が多い。 In general, digital magnetic recording has the characteristics of being able to economically record a large amount of information and to store it stably over a long period of time. The information signal modulation methods for this purpose are RZ (Retrn to Zero) and RB.
(Return to Bias), NRZ (Non-Return to
Zero), NRZI (Non-Retun to Zero I), FM
(Frequency Modulation), PE (Phase
Encoding), MFM (Modified Frequency)
Various methods have been proposed, including M 2 FM (Modified MFM) and M 2 FM (Modified MFM). On the other hand, recently, various new modulation methods other than these have been proposed. for example,
4/5MNRZI (Modified Non-Return to Zero
I), 3PM (3 Position Modulation), ZM
(Zero Modulation) etc. Furthermore, recently, as density increases, new modulation methods other than those mentioned above are being considered, but in digital magnetic recording, the detection window width T W , the minimum magnetization reversal interval T nio , or the ratio of the linear bit density to the maximum magnetization reversal density DR
It is said that a modulation method with a large (Devsity Ratio) is desirable. Furthermore, the ease of increasing the density is often expressed as the product of the minimum magnetization reversal interval T nio and the detection window width T W .

本発明はこのような要望に鑑みなされたもので
あり、最小磁化反転間隔Tnioが1.5Tと3PM方式
と同じく、最大磁化反転間隔Tnaoが5.5Tと3PM
方式の6Tより小さく、又、検出窓幅TWが0.5Tと
3PM方式を同じく、最小磁化反転間隔Tnioと検
出窓幅TWとの積も0.75T2と3PM方式と同じ、つ
まり、3PM方式の最大磁化反転間隔Tnaoを0.5T
改善したセルフクロツキング可能な変調方式を提
供するものである。 The present invention was made in view of these demands, and the minimum magnetization reversal interval T nio is 1.5T, similar to the 3PM method, and the maximum magnetization reversal interval T nao is 5.5T and 3PM.
It is smaller than the 6T of the method, and the detection window width T W is 0.5T.
Same as the 3PM method, the product of the minimum magnetization reversal interval T nio and the detection window width T W is also 0.75T 2 The same as the 3PM method, that is, the maximum magnetization reversal interval T nao of the 3PM method is 0.5T.
An improved self-clockable modulation scheme is provided.

以下に本発明について実施例の図面と共に詳細
に説明する。 The present invention will be described in detail below with reference to drawings of embodiments.

第１図は3PM方式の変換テーブルである。
3PM方式は、３ビツトのデータを６ビツトの符
号語に変換して、その符号語の系列をNRZIで変
調するものである。符号語は、ビツト“１”と次
のビツト“１”との間に少なくとも２つのビツト
“０”が入るのが特徴であるが、時系列的に古い
符号語の５ビツト目P5が“１”で、さらにこれ
に続く符号語の１ビツト目P1が“１”であるよ
うな符号語の系列が生じた場合、ビツト“１”と
次のビツト“１”との間に入るビツト“０”の最
小連続個数を２とする条件が破られてしまうた
め、この場合は、古い符号語の５ビツト目P5と
これに続く符号語の１ビツト目P1とをビツト
“０”に反転し、古い符号語の６ビツト目P6をビ
ツト“１”に反転する特別の規則を設けている。
さらに言うならば、ある符号語の５ビツト目P5
が“１”で次の符号語の１ビツト目P4が“１”
の場合は最小反転間隔がＴとなつてしまうので、
この場合は上記P5、P1と共に“０”に反転し、
常に“０”である６ビツト目P6を“１”に反転
して、反転間隔1.5Tに保つようにしている。さ
らに、この3PM方式では符号語の系列のビツト
“１”とビツト“１”との間に入る最大ビツト
“０”の個数を11に制限している。従つて最大反
転間隔を6Tとなるように符号語が選択されてい
る。 Figure 1 is a conversion table for the 3PM method.
The 3PM method converts 3-bit data into a 6-bit code word and modulates the code word sequence with NRZI. A code word is characterized by having at least two bits "0" between a bit "1" and the next bit "1", but the fifth bit P5 of the chronologically older code word is " If a sequence of code words occurs in which the first bit P1 of the following code word is "1", the bits between bit "1" and the next bit "1" Since the condition that the minimum number of consecutive “0”s is 2 is violated, in this case, the 5th bit P5 of the old codeword and the 1st bit P1 of the following codeword are set to bit “0”. A special rule is provided to invert the 6th bit P6 of the old code word to bit "1".
In other words, the 5th bit of a code word P 5
is “1” and the 1st bit P4 of the next code word is “1”
In the case of , the minimum reversal interval becomes T, so
In this case, it is inverted to “0” along with P 5 and P 1 above,
The 6th bit P6 , which is always "0", is inverted to "1" to maintain an inversion interval of 1.5T. Furthermore, in this 3PM system, the maximum number of bits "0" that can be inserted between bits "1" in a code word sequence is limited to 11. Therefore, the codeword is selected so that the maximum inversion interval is 6T.

これに対し、第２図は本発明の４―８変換
FEM―２（Four to Eight Modulation）の変換
テーブルである。本方式は４ビツトのデータを８
ビツトの符号語に変換して、その符号語の系列を
NRZIで変調するものである。符号語は、第３図
ａに示すようにビツト“１”と次のビツト“１”
との間に少なくとも２つ以上のビツト“０”が入
り、多くとも10ケ以下となるように制限が加えら
れているのが特徴であるが、第３図ｂに示すよう
に時系列的に古い符号語の７ビツト目P7が“１”
で、さらにこれに続く符号語の１ビツト目P1が
“１”であるように符号語の系列が生じた場合は、
本方式の条件が破られてしまうので、この場合
は、古い符号語の７ビツト目P7とこれに続く符
号語の１ビツト目P1とをビツト“０”に反転し、
古い符号語の８ビツト目P8ビツト“１”に反転
する特別の規則を設けている。しかし、第２図の
バイナリデータワードNo.５の後にNo.１が続く場合
は符号語としては となり、最大磁化反転間隔Tnax＝6Tが発生する。
そのため、この場合は第３図ｃに示すようにNo.５
の符号語の８ビツト目P8をビツト“１”に反転
し、さらに、No.１の符号語の３ビツト目P3をビ
ツト“１”に反転する。この場合の符号語列は次
のようになる。 In contrast, Figure 2 shows the 4-8 conversion of the present invention.
This is a conversion table for FEM-2 (Four to Eight Modulation). This method converts 4-bit data into 8
Convert the bit codeword and convert the codeword series to
It is modulated by NRZI. The code word consists of a bit “1” and the next bit “1” as shown in Figure 3a.
It is characterized by the fact that there are at least two or more bits "0" between them, and there is a restriction that there are no more than 10 bits at most, but as shown in Figure 3b, the time series The 7th bit P7 of the old code word is “1”
Then, if a sequence of code words occurs such that the first bit P1 of the following code word is "1", then
Since the conditions of this method are violated, in this case, the 7th bit P7 of the old codeword and the 1st bit P1 of the following codeword are inverted to bit "0",
A special rule is provided to invert the 8th bit P of the old code word to 1. However, if binary data word No. 5 in Figure 2 is followed by No. 1, it is not used as a code word. Therefore, the maximum magnetization reversal interval T nax =6T occurs.
Therefore, in this case, No. 5 as shown in Figure 3c.
The 8th bit P8 of the No. 1 code word is inverted to bit "1", and the 3rd bit P3 of the No. 1 code word is inverted to bit "1". The code string in this case is as follows.

この場合のNo.１の符号語は第２図のNo.８と同じも
のになる。しかし、この場合のFEM―２の復調
は、時系列的に古い符号語の８ビツト目P8と後
続する符号語３ビツト目P3が同時にビツト“１”
であることを検出し、古い符号語の８ビツト目
P8と後続する符号語の３ビツト目をビツト“０”
に反転すれば可能となることは明らかである。つ
まり、符号語No.８は後続する符号語として使われ
る場合は符号語の１ビツト目P1、２ビツト目P2
が共にビツト“０”であるので古い符号語の８ビ
ツト目P8は絶体にビツト“１”とはならない。
従つて、古い符号語の８ビツト目P8がビツト
“１”で、次に符号語No.８が続く場合は特別の規
則が適用された場合として区別することができ
る。即ち、符号語の８ビツト目P8は、 ××××××10‖１××××××× のビツト“１”とビツト“１”との間に少なくと
もビツト“０”を２個以上含むという本方式の条
件を満足しない場合 ××××××01‖０××××××× なる変換を行ない条件を満足させるためのフラグ
ビツトとして使うことと、符号語のNo.５とNo.１が
連続する場合に発生する最大磁化反転間隔Tnax
＝6Tを5.5Tに改善するためのフラグビツトとし
て使う。本方式の最大磁化反転間隔Tnax5.5Tは
符号語No.５とNo.２が連続する場合及びNo.４とNo.１
が連続する場合に発生する。即ち、 第４図はFEM―２方式と従来の変調方式との
記録電流波形を比較して示す図であり、同図アは
データ、イはNRZI方式による波形、ウはFM方
式による波形、エはMFM方式による波形、オは
3PM方式による波形、カはFEM―２方式による
波形である。なお、図で、Ｔはビツト周期を示し
ている。 The code word No. 1 in this case is the same as No. 8 in FIG. However, in the demodulation of FEM-2 in this case, the 8th bit P8 of the chronologically older codeword and the 3rd bit P3 of the following codeword are simultaneously set to bit "1".
The 8th bit of the old code word
P 8 and the 3rd bit of the following code word is set to “0”
It is clear that this is possible if the equation is reversed. In other words, when code word No. 8 is used as a subsequent code word, the first bit P 1 and the second bit P 2 of the code word
Since both bits are "0", the 8th bit P8 of the old code word is definitely not a bit "1".
Therefore, if the 8th bit P8 of the old code word is bit "1" and code word No. 8 follows next, it can be distinguished as a case where a special rule is applied. In other words, the 8th bit P8 of the code word has at least two bits “0” between bits “1” and bits “1” of ××××××10‖1×××××××. If the condition of this method of including the above is not satisfied, use the following conversion as ××××××01‖0××××××× and use it as a flag bit to satisfy the condition. Maximum magnetization reversal interval T nax that occurs when No. 1 is consecutive
= Used as a flag bit to improve 6T to 5.5T. The maximum magnetization reversal interval T nax 5.5T of this method is when code words No. 5 and No. 2 are consecutive, and No. 4 and No. 1 are consecutive.
Occurs when consecutive. That is, Figure 4 shows a comparison of recording current waveforms between the FEM-2 method and the conventional modulation method, where A is the data, B is the waveform by the NRZI method, C is the waveform by the FM method, and D is the MFM. Waveform by method, O is
The waveform is based on the 3PM method, and the waveform is based on the FEM-2 method. In the figure, T indicates the bit period.

現在、大容量磁気デイスク装置で最も一般に用
いられているMFM方式の場合は、磁化反転間隔
はＴ、1.5T、2Tの３種類であり、最小磁化反転
間隔TnioはＴである。MFM方式以外の変調方式
の場合は、TnioとしてNRZIがＴ、FMが0.5Tで
ある。このように従来の変調方式の多くは最小磁
化反転間隔がＴ以下であり、したがつて、DRは
１以下であつた。一方、3PMと本方式のFEM―
２では最小磁化反転間隔Tnioが1.5Tであり、DR
＝1.5である。したがつて、最小磁化反転間隔を
MFMと同じにすれば、線ビツト密度を1.5倍にす
ることができる。 In the case of the MFM method, which is currently most commonly used in large-capacity magnetic disk devices, there are three types of magnetization reversal intervals: T, 1.5T, and 2T, and the minimum magnetization reversal interval T nio is T. In the case of a modulation method other than the MFM method, T nio is T for NRZI and 0.5T for FM. As described above, in most of the conventional modulation systems, the minimum magnetization reversal interval is T or less, and therefore the DR is 1 or less. On the other hand, 3PM and the FEM of this method
2, the minimum magnetization reversal interval T nio is 1.5T, and DR
= 1.5. Therefore, the minimum magnetization reversal interval is
If it is the same as MFM, the linear bit density can be increased by 1.5 times.

第５図は参考までに各種変調方式の比較を示し
ている。 FIG. 5 shows a comparison of various modulation methods for reference.

以上説明したように本発明によれば、最小磁化
反転間隔1.5T、最大磁化反転間隔5.5T、検出窓
幅TW0.5T、最小磁化反転間隔Tnioと検出窓幅TW
との積0.75T2のセルフクロツキング可能な変調方
式を提供することができる。 As explained above, according to the present invention, the minimum magnetization reversal interval 1.5T, the maximum magnetization reversal interval 5.5T, the detection window width T W 0.5T, the minimum magnetization reversal interval T nio and the detection window width T W
A self-clocking modulation scheme with a product of 0.75T 2 can be provided.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は３PM方式の変換テーブル図、第２図
は本発明のデイジタル変調方法におけるFEM―
２の変換テーブル図、第３図はFEM―２におけ
る最大磁化反転間隔の発生する場合及び特別規則
適用例を説明するための図、第４図はFEM―２
と従来変調方式の記録電流波形の比較図、第５図
は各種変調方式の比較図である。 Figure 1 is a conversion table diagram of the 3PM method, and Figure 2 is a diagram of the FEM in the digital modulation method of the present invention.
2 conversion table diagram, Figure 3 is a diagram for explaining the case where the maximum magnetization reversal interval occurs in FEM-2 and an example of application of special rules, Figure 4 is FEM-2
FIG. 5 is a comparison diagram of the recording current waveforms of the conventional modulation method and the conventional modulation method, and FIG. 5 is a comparison diagram of various modulation methods.

Claims (1)

【特許請求の範囲】 １ 高密度記録するためのデイジタル変調方法で
あつて、データビツトを４ビツト単位に分割し、
この４ビツト単位のデータビツトの16通りの組合
せに対し、８ビツトの符号語
（P1P2P3P4P5P6P7P8）としてそのデータ時間系列
群を 00000100 00001000 00010000 00100000 01000000 00010010 10010010 00100100 01001000 10010000 10000010 00100010 01000010 01000100 10000100 10001000 とし、それらのデータ列を対応させ、符号語と符
号語の連結部における符号語系列パターンの時系
列的に古い符号語の７ビツト目P7と８ビツト目
P8及び時系列的に新しい符号語の１ビツト目P1
が101となる場合は前記８ビツト目P8をビツト
“１”に反転し、前記７ビツト目P7と１ビツト目
P1をビツト“０”に反転させると共に、符号語
に符号語が後続する場合、符号語の８ビツ
ト目P8をビツト“１”に反転し、さらに符号語
の３ビツト目P3をビツト“１”に反転させ、
その後NRZIで変調することを特徴とするデイジ
タル変調方法。 ２ 符号語系列のビツト“１”とビツト“１”と
の間にビツト“０”を少なくとも２個以上含み、
多くとも10個以下となるように構成したことを特
徴とする特許請求の範囲第１項記載のデイジタル
変調方法。[Claims] 1. A digital modulation method for high-density recording, which divides data bits into 4-bit units,
For these 16 combinations of data bits in 4-bit units, the data time series group is expressed as an 8-bit code word (P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 ) 00000100 00001000 00010000 00100000 01000000 00010010 10010010 00100100 01001000 10010000 10000010 00100010 01000010 01000100 10000100 10001000, these data strings are made to correspond, and the codeword sequence pattern at the concatenation part of codewords is 7th bit P 7 and 8 of chronologically old code word Bit eyes
P 8 and the first bit of the chronologically new code word P 1
is 101, the 8th bit P8 is inverted to bit "1", and the 7th bit P7 and the 1st bit are
In addition to inverting P1 to bit "0", if the codeword is followed by a codeword, inverting the 8th bit P8 of the codeword to bit "1", and then inverting the 3rd bit P3 of the codeword. Invert it to “1”,
A digital modulation method characterized by subsequently modulating with NRZI. 2 The codeword sequence contains at least two bits “0” between bits “1” and
2. The digital modulation method according to claim 1, wherein the number of digital modulation is 10 or less at most.
JP10425782A 1982-06-16 1982-06-16 Digital modulating method Granted JPS58220214A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP10425782A JPS58220214A (en) 1982-06-16 1982-06-16 Digital modulating method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP10425782A JPS58220214A (en) 1982-06-16 1982-06-16 Digital modulating method

Publications (2)

Publication Number Publication Date
JPS58220214A JPS58220214A (en) 1983-12-21
JPH0150997B2 true JPH0150997B2 (en) 1989-11-01

Family

ID=14375873

Family Applications (1)

Application Number Title Priority Date Filing Date
JP10425782A Granted JPS58220214A (en) 1982-06-16 1982-06-16 Digital modulating method

Country Status (1)

Country Link
JP (1) JPS58220214A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1040824C (en) 1994-07-08 1998-11-18 日本胜利株式会社 Digital modulating/demodulation method and apparatus using same

Also Published As

Publication number Publication date
JPS58220214A (en) 1983-12-21

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