JP3869186B2 - Data demodulation method for magnetic recording data - Google Patents

Description

【００４０】
従来装置では、前述した図１５に示されているように、Ｐ6 及びＰ7 を”０”と誤読してしまうが、上述した実施形態にかかる装置では、Ｐ1 〜Ｐ7 に対応する閾値Ｄ1 〜Ｄ7 との比較を行って復調を行い、Ｐ6 ＞Ｄ6 及びＰ7 ＞Ｄ7 となっていることから、”１”のように正しく読取りが行われる。
【００４１】
このとき、本実施形態における磁気記録データのデータ復調方法では、間隔データとして磁束反転時間の逆数である周波数を採用していることから、磁気記録媒体が停止する直前のデータが０方向に収束されて発散が防止されるようになっている。
【００４２】
また、本実施形態における磁気記録データのデータ復調方法では、カテゴリー分類して得た周波数曲線にデータの補充を行っていることから、閾値曲線Ｄが精度良く得られるようになっている。
【００４３】
以上、本発明者によってなされた発明の実施形態を具体的に説明したが、本発明は上記実施形態に限定されるものではなく、その要旨を逸脱しない範囲で種々変形可能であるというのはいうまでもない。
【００４４】
例えば、本発明にかかる磁気記録媒体は、上述した実施形態のような磁気カードに限定されるものではなく、他の多種多様な磁気記録媒体に対しても同様に適用することができるものである。また、磁気記録媒体をマニュアルで搬送するものに限らず、モータ等を用いて自動搬送するようにした装置に対しても、本発明は同様に適用可能である。
【００４５】
【発明の効果】
以上述べたように、請求項１又は２記載の磁気記録データのデータ復調方法は、磁気記録媒体に書き込まれた磁気記録データ全体の間隔データに基づいて、「０」データ又は「１」データのいずれかであるかを判定する閾値曲線を求めており、間隔データの全体からデータ判定を行うようにしていることから、部分的に発生した急激な速度変動により生じた異常データも、精度良く判定されるようになっていて、簡易な構成で、記録媒体の搬送速度の変動があっても安定的に復調を行うことができる。
【００４６】
このとき、請求項３又は４記載の磁気記録データのデータ復調方法では、間隔データとして磁束反転時間の逆数である周波数を採用していることから、磁気記録媒体が停止する直前のデータが０方向に収束されて発散が防止されるようになっていることから、上述した効果を確実に得ることができる。
【００４７】
また、請求項５記載の磁気記録データのデータ復調方法では、カテゴリー分類して得た周波数曲線にデータの補充を行っていることから、閾値曲線が精度良く得られることから、上述した効果を一層確実に得ることができる。
【図面の簡単な説明】
【図１】本発明に係る磁気記録データのデータ復調方法の一実施形態を表したメインフロー図である。
【図２】図１に表されたメインフロー図中のカテゴリー分類手順の一実施形態を表したサブフロー図である。
【図３】図３に表されたサブフロー図の続きを表したサブフロー図である。
【図４】図１に表された本発明に係る磁気記録データのデータ復調方法を実施するための装置例を表したブロック線図である。
【図５】磁束反転間の速度（周波数）データを表した線図である。
【図６】カテゴリー分類手順の実施例を表した模式図である。
【図７】カテゴリー分類後の周波数曲線を表した線図である。
【図８】図７に表した周波数曲線にデータ補充を行った後の線図である。
【図９】図８に表した周波数曲線を平滑化した線図である。
【図１０】図９に表した周波数曲線から閾値曲線を求めた線図である。
【図１１】図１０に表した閾値曲線を設定した状態を表した線図である。
【図１２】従来誤読を生じていた部分を拡大して表した磁束反転周波数を表した線図である。
【図１３】従来における磁気記録データのデータ復調方法を実施するための装置例を表したブロック線図である。
【図１４】従来における磁気記録データのデータ復調方法の実行手順を表したタイミング関係図である。
【図１５】従来の誤読状態を表した模式図である。
【符号の説明】
１１ 磁気記録媒体
１２ 磁気ヘッド
１３ 増幅器
１４ Ａ／Ｄ変換器
１５ メモリ
１６ ＣＰＵ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data demodulation method for magnetic recording data for demodulating magnetic recording data written on various magnetic recording media such as a magnetic card.
[0002]
[Prior art]
In general, in various recording / reproducing apparatuses that handle magnetic recording media such as magnetic cards, for example, as shown in FIG. 13, magnetic recording data information (see FIG. 14 (a)) written on the magnetic recording medium 1, A signal (see FIG. 14 (b)) that is reproduced as an analog signal by the magnetic head 2 and passed through the amplifier 3 is waveform-shaped by the comparator 4 and binarized data (FIG. 14 (e)). (See FIG. 14C), and the peak position of the analog reproduction signal described above is detected by the peak detection circuit 5 (see FIG. 14C), and the waveform is shaped by the comparator 6 and binarized (see FIG. 14). 14 (d)), a timing signal (see FIG. 14 (f)) is generated from the timing generation circuit 7 and is used for the data discrimination circuit or the CPU 8 to detect the adjacent peak position. Measures the time interval between the teeth, is performed demodulation of the magnetic recording data thereby based on the interval data obtained.
[0003]
In the data discrimination circuit or CPU 8, a reference time αT is set for the interval data T, and binary determination is performed by detecting the presence or absence of signal polarity inversion within the reference time αT to obtain demodulated data. ing. When performing such demodulation, in particular in a manual recording / reproducing apparatus, in order to cope with fluctuations in the conveyance speed when a magnetic recording medium such as a magnetic card is manually conveyed, for example, as shown in FIG. Such a bit following method has been proposed. In this case, with respect to the bit interval data Tk (k = 1, 2,...) Currently being demodulated, the reference time αTk−1 (1) is used by using the immediately preceding interval data Tk−1. / 2 <α <1) is set and the values are compared in magnitude. According to this bit tracking method, even if the transport speed fluctuates and the bit time interval of the reproduction signal slightly fluctuates, the occurrence of misreading is prevented by calculating the reference signal from the immediately preceding bit. It is like that.
[0004]
[Problems to be solved by the invention]
However, even in such a bit following method based on the immediately preceding data, if the conveyance speed of a recording medium such as a magnetic card fluctuates rapidly, it becomes impossible to follow the fluctuation in speed, leading to misreading. There is a risk. For example, the interval data T4 in FIG. 15 is a "1" signal, and the signal polarity should be inverted within the time range of the reference time αT3 set by the immediately preceding interval data T3. However, in practice, the time interval may be greatly extended due to the adoption of the above-described manual method, etc., and as a result, signal polarity inversion does not occur within the time range of the reference time αT3. The “1” signal is misread as a “0” signal. Even in the case of the auto method using motor driving, similar misreading may occur.
[0005]
Accordingly, an object of the present invention is to provide a data demodulating method for magnetic recording data which can be demodulated stably even if the conveyance speed of the magnetic recording medium varies with a simple configuration.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the data demodulating method of magnetic recording data according to claim 1, the peak position in the reproduction signal of the magnetic recording data written on the magnetic recording medium is detected, and the time between adjacent peak positions is detected. In the data demodulating method of magnetic recording data for demodulating magnetic data information composed of “0” signal or “1” signal based on interval data obtained by measuring the interval, each of all interval data relating to the peak position of the reproduction signal is described. Are classified into three categories, “0” data, “1” data, and “gray zone” data, which is unknown, and smoothing processing is performed for the categories of “0” data and “1” data, respectively. To obtain two smoothing curves and average these two smoothing curves to obtain “0” data and “1” data Set seeking partitioned threshold curves, with a threshold curve that setting, the are to perform binarization judgment of the entire interval data.
[0007]
Further, in the data demodulating method of magnetic recording data according to claim 2, when performing classification of the three categories according to claim 1, magnetic flux reversal time for each series of magnetic domains is used as interval data regarding the peak position of the reproduction signal. By adopting Tk, obtaining the rate of change Tk / Tk-1 between the magnetic flux reversal times Tk-1 and Tk in the adjacent magnetic domains, and comparing the rate of change Tk / Tk-1 with the reference value, The above three categories are classified.
[0008]
Further, in the data demodulating method of the magnetic recording data according to claim 3, when the rate of change Tk / Tk-1 between the magnetic flux reversal times Tk-1 and Tk according to claim 2 is obtained, each magnetic flux reversal thereof is determined. The rate of change Vk-1 / Vk of the frequencies Vk-1, Vk, which are the reciprocals 1 / Tk-1, 1 / Tk of the times Tk-1, Tk, is obtained, and the rate of change Vk-1 / Vk of the frequencies Vk-1, Vk is obtained. The three categories are classified by comparing Vk with a reference value.
[0009]
Furthermore, in the data demodulating method for magnetic recording data according to claim 4, two frequency curves corresponding to “0” data and “1” data are obtained by classifying the three categories according to claim 3. The two smoothing curves are obtained by smoothing each of the two frequency curves.
[0010]
On the other hand, in the data demodulating method of magnetic recording data according to claim 5, two frequency curves corresponding to “0” data and “1” data are obtained by classifying the three categories according to claim 4, Replenishment processing is performed so that the number of data in each of the two frequency curves is almost the same, and smoothing processing by moving average is performed on the two frequency curves subjected to the supplementation processing, and two smoothing operations are performed. I try to find a curve.
[0011]
3. The method of demodulating magnetic recording data according to claim 1 or 2 having such a configuration, based on the interval data of the entire magnetic recording data written on the magnetic recording medium, "0" data or "1" data Since the threshold curve for determining whether or not any of the abnormal data caused by the sudden speed fluctuations that partially occurred is also accurately determined by the threshold curve obtained from the entire magnetic interval data. It has become so.
[0012]
At this time, in the data demodulating method of the magnetic recording data according to claim 3 or 4, since the frequency which is the reciprocal of the magnetic flux reversal time is adopted as the interval data, the data immediately before the magnetic recording medium stops is zero direction. The data is converged to prevent data divergence.
[0013]
In the data demodulating method for magnetic recording data according to the fifth aspect of the present invention, since the data is supplemented to the frequency curve obtained by the category classification, the threshold curve can be obtained with high accuracy.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, in a recording / reproducing apparatus employed when the method according to the present invention is used for reading a magnetic card, for example, as shown in FIG. 4, magnetic recording data (see FIG. 4) written on a magnetic recording medium 11 is used. 14 (a)) is reproduced as an analog signal by the magnetic head 12, and the analog reproduction signal (see FIG. 14 (b)) after passing through the amplifier 13 is counted by the A / D converter 14. The counted data is temporarily stored in the memory 15. The data in the memory 15 is appropriately extracted by the CPU 16, and processing according to an embodiment of the present invention as described below is performed.
[0015]
The CPU 16 first detects all the interval data T by referring to all the data of the magnetic reproduction signal stored in the memory 15 and measuring the interval data T for every peak therefrom. Then, as shown in step 1 in FIG. 1, frequency data (reciprocal of time) as shown in FIG. 5 is obtained by calculating the reciprocal V for every interval data T obtained as described above. Frequency data) is obtained, and the frequency data is stored in the memory 15 in step 2 of FIG.
[0016]
At this time, the magnetic flux reversal time (interval data T) for the “0” signal portion (1F) should be about twice the magnetic flux reversal time (interval data T) for the “1” signal portion (2F). Therefore, when the frequency is set, the opposite is true, and the frequency data corresponding to the “1” signal portion (2F) is about twice the frequency data corresponding to the “0” signal portion (1F). Therefore, as shown in FIG. 5 described above, the entire frequency data appears separately in two upper and lower curves. That is, of the two frequency curves, the upper curve corresponds to the “1” signal portion (2F), and the lower curve corresponds to the “0” signal portion (1F). ing.
[0017]
Next, considering the rate of change in frequency between the “0” signal portion (1F) and the “1” signal portion (2F) described above,
(1) The frequency of the “1” signal portion (2F) with respect to the “0” signal portion (1F) is about twice.
(2) The frequency of the “0” signal portion (1F) with respect to the “1” signal portion (2F) is about 0.5 times.
(3) The frequency of the “0” signal portion (1F) with respect to the “0” signal portion (1F) and the frequency of the “1” signal portion (2F) with respect to the “1” signal portion (2F) are each about 1 time. is there.
Therefore, the frequency change rate converges to three points. By utilizing this, in step 3 of FIG. 1, each of the above-described frequency data is changed to “0” data, “1” data, and The classification is made into three categories of “gray zone” data, which of which is unknown.
[0018]
In the categorization procedure in this embodiment, as shown in FIG. 2, first, the counter i is set to “1”, and a flag to be described later is set to “−” (step 1). This is because by setting the initial setting of the flag to “−”, the data on the buffer is regarded as a preamble at the time of detecting STX that is the first data, and the data is determined to be “0” data. This is to make it possible.
[0019]
Next, the rate of change G (= Vi-1 / Vi) between the frequencies Vi-1 and Vi between adjacent magnetic flux reversals is sequentially calculated (step 2), and the rate of change G and the value of the flag to be described next are obtained. By examining, buffer data is categorized accordingly. The frequency change rate G at this time is a value obtained by dividing the frequency data Vi-1 on the front side of the two adjacent frequency data Vi-1 and Vi by the frequency data Vi on the rear side (Vi-1 / Vi). ) Is adopted.
[0020]
Then, after the flag at that time is once set to the previous value “tmp” (step 3), the value of the flag is set as follows.
a) The flag is “+” when the frequency Vi suddenly increases and the rate of change G falls below 0.7 (G ≦ 0.7).
b) The flag is "-" when the frequency Vi decreases rapidly and the rate of change G exceeds 1.4 (G ≧ 1.4).
c) When there is no sudden change in the frequency Vi and the change rate G is within the range of 0.7 to 1.4 (0.7 <G <1.4), the flag is left as it is and the frequency data is stored. Store (store) temporarily in the buffer.
d) Similarly, there is no sudden change in the frequency Vi, but when the rate of change G is in the vicinity of 0.7 and 1.4 (G≈0.7, G≈1.4), the flag is set to “0”.
[0021]
The above three categorization is performed in cases other than c). First, in the case of d) (Yes in step 4), the flag is set to “0”. (Step 5) The flag tmp before being changed is checked (Step 6). If the flag tmp is “+”, the data on the buffer is determined as “1” data (2F) (Step 7). If the flag tmp before the change is “−”, the data on the buffer is determined as “0” data (1F) (step 8). On the other hand, if the flag tmp before the change is “0”, the data on the buffer is determined as “gray zone” data (step 9).
[0022]
Next, in the case of c) (Yes in step 10), the process proceeds to step 18 in FIG. 3 without performing categorization as described above. The procedure after step 18 will be described later.
[0023]
On the other hand, in the case of b) (No in step 11 in FIG. 2), the flag is set to “−” (step 12), and the flag tmp before being changed is checked (step 6). If the flag tmp is “+”, the data on the buffer is determined as “1” data (2F) (step 7). If the flag tmp before the change is “−”, the data on the buffer is determined. It is determined that the data is “0” (1F) (step 8). If the flag tmp before the change is “0”, the data on the buffer is determined as “gray zone” data (step 9).
[0024]
Further, in the case of a) described above (Yes in Step 11), after setting the flag to “+” (Step 13), the flag tmp before being changed is checked (Step 14 in FIG. 3). If the flag tmp is “0”, the data on the buffer is determined as “gray zone” data (step 15 in FIG. 3). In other cases, the data on the buffer is determined to be “0” data (1F) (step 16 in FIG. 3).
[0025]
As described above, in the cases of a), b) and d) other than the above c), after performing the categorization by the operation of each step described above, the counter and the buffer are cleared (step 17), as described above. The frequency data Vi determined in (1) is stored on the buffer (step 18).
[0026]
Then, after the counter is incremented (step 19), when the counter does not exceed the predetermined value set in advance (No in step 20), and when it is not the last frequency data (No in step 21). After the initial counter value i is set to (i + 1) (step 22), the process returns to the beginning and the above-described procedure is repeated. When the last frequency data is reached (Yes in step 21), the process is terminated.
[0027]
On the other hand, if the counter exceeds a preset value and the frequency data on the buffer also exceeds a certain value (Yes in step 20), the data on the buffer is regarded as a postamble. It is determined that the data is “0” (1F) (step 23), and the process ends.
[0028]
Here, the actual magnetic reproduction signal is as shown in the curve of FIG. 6, and the magnetic flux reversal time Tk, frequency Vk, and rate of change (Vi-1 / Vi) for each magnetic domain are shown in FIG. The procedure of categorization when it is as shown in the table will be described. First, when looking in order from the frequency V1, the rate of change at the frequency V1 is 1.0, which falls within the range of 0.7 to 1.4. Therefore, in this case, the processing related to c) described above is performed, and the frequency data is only stored (stored) in the buffer without changing the flag.
[0029]
Next, the rate of change at the frequency V2 is 0.52, which is well below 0.7. Therefore, in this case, the processing related to a) described above is performed, and the flag immediately before this time is “-”, so the frequency data (V0, V1) on the buffer is changed to “0” data (1F). Is determined. After the buffer is cleared, V2 is stored in the buffer and the flag is set to "+".
[0030]
On the other hand, the rate of change at the frequency V3 is 1.08 and again falls within the range of 0.7 to 1.4. Therefore, in this case, the same processing as the frequency V1 described above is performed, and the frequency data is stored (stored) in the buffer without changing the flag.
[0031]
Further, the rate of change at the frequency V4 is 1.87, which is much higher than 1.4. Therefore, in this case, the processing related to b) described above is performed, and the flag immediately before this time is “+”. Therefore, the frequency data (V2, V3) on the buffer is changed to “1” data (2F). Is determined. After the buffer is cleared, V4 is stored in the buffer and the flag is set to "-".
[0032]
Further, the rate of change at the frequency V5 is 0.72, which is very close to 0.7. In this case, the above-described processing relating to d) is performed. That is, since the flag immediately before this time is "-", the frequency data V4 on the buffer is determined as "0" data (1F). After the buffer is cleared, V5 is stored in the buffer and the flag is set to "0". Thereafter, the same categorization operation is performed until the frequency data is completely lost or a postamble is detected.
[0033]
After all the frequency data is classified into three categories by such a procedure, each of “0” data (1F) and “1” data (2F) is divided into two categories as shown in FIG. Form a frequency curve.
[0034]
Next, returning to FIG. 1 again, as in step 4 in the same figure, each frequency data is supplemented so that the number of data in the data area of the magnetic recording area becomes equal, and the two frequency curves described above are shown in FIG. Modify as in 8. Thereafter, as shown in step 5 of FIG. 1, smoothing processing by moving average is performed to obtain two corrected frequency curves 1F and 2F as shown in FIG.
[0035]
Further, as shown in step 6 of FIG. 1, a curve D passing through the middle of each frequency curve for each of the corrected “0” data (1F) and “1” data (2F) is obtained as shown in FIG. . The position of the intermediate curve D at this time is a value for determining whether it is “1” data, which is obtained by multiplying the curve of “0” data (1F) by (1 / α), where αT is the reference time of the bit. , The curve of “1” data (2F) is multiplied by (1 / (2α)), and the average value with the value for determining whether it is “0” data. Then, the intermediate curve D obtained by averaging is adopted as a threshold curve for binary determination, and binarization determination is performed on all frequency data as shown in FIG.
[0036]
In this binarization determination, first, the counter is set to 0 as in step 7 of FIG. 1, and then the frequency data Vi stored in the memory and the corresponding threshold value Di are sequentially increased or decreased as in step 8. Compare. Then, when the frequency data Vi is below the threshold value Di as in step 9, it is determined as “0”. On the other hand, if the frequency data Vi is equal to or exceeds the threshold value Di, it is determined as “1”. At this time, as shown in step 10, the process proceeds to the next frequency data Vi + 1 and the magnitude comparison is performed as in step 11. I do. Usually, when the determination result is “1”, the next data should also exceed the corresponding threshold value. Therefore, in such a case, “1” is officially set at the next step 12. If not, it is recognized in step 13 that an abnormality has been detected in the sub-bit, and the process ends after performing appropriate processing.
[0037]
Then, after the determination operation as described above is repeated until reaching the final frequency data as in steps 14 and 15, the process is terminated.
[0038]
As described above, in the data demodulating method of magnetic recording data according to the present embodiment, “0” based on all frequency data which are interval data of the entire magnetic recording data written on the magnetic card 11 as the magnetic recording medium. The threshold curve D for determining whether the data is “1” data (1F) or “1” data (2F) is obtained, and data determination is performed from the entire interval data. Therefore, abnormal data generated due to a sudden speed fluctuation partially generated is also determined with high accuracy.
[0039]
For example, the range surrounded by the wavy line in FIG. 5 is a portion where the conveyance speed of the magnetic card fluctuates rapidly, but the portions P1 to P7 shown in FIG. The true values are as shown in the table below.
[Table 1]

[0040]
In the conventional apparatus, as shown in FIG. 15 described above, P6 and P7 are misread as “0”. However, in the apparatus according to the above-described embodiment, threshold values D1 to D7 corresponding to P1 to P7 are set. And P6> D6 and P7> D7, so that reading is correctly performed as "1".
[0041]
At this time, in the data demodulating method of the magnetic recording data in this embodiment, since the frequency which is the reciprocal of the magnetic flux reversal time is adopted as the interval data, the data immediately before the magnetic recording medium stops is converged in the 0 direction. To prevent divergence.
[0042]
In the data demodulation method of magnetic recording data in this embodiment, the threshold curve D can be obtained with high accuracy because the data is supplemented to the frequency curve obtained by the category classification.
[0043]
Although the embodiments of the invention made by the present inventor have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. Not too long.
[0044]
For example, the magnetic recording medium according to the present invention is not limited to the magnetic card as in the above-described embodiment, and can be similarly applied to various other magnetic recording media. . In addition, the present invention is not limited to the one that manually conveys the magnetic recording medium, but can be applied to an apparatus that automatically conveys the magnetic recording medium using a motor or the like.
[0045]
【The invention's effect】
As described above, the data demodulating method of the magnetic recording data according to claim 1 or 2 is based on the interval data of the entire magnetic recording data written on the magnetic recording medium. Since a threshold curve is determined to determine whether it is either, and data is determined from the entire interval data, abnormal data generated due to abrupt speed fluctuations that occur partially can also be accurately determined. Thus, with a simple configuration, it is possible to perform stable demodulation even if there is a change in the conveyance speed of the recording medium.
[0046]
At this time, in the data demodulating method of the magnetic recording data according to claim 3 or 4, since the frequency which is the reciprocal of the magnetic flux reversal time is adopted as the interval data, the data immediately before the magnetic recording medium stops is zero direction. Therefore, the above-described effects can be obtained with certainty.
[0047]
Further, in the data demodulating method for magnetic recording data according to claim 5, since the data is replenished to the frequency curve obtained by the category classification, the threshold curve can be obtained with high accuracy, so that the above-described effect is further improved. You can definitely get it.
[Brief description of the drawings]
FIG. 1 is a main flow diagram showing an embodiment of a method for demodulating magnetic recording data according to the present invention.
FIG. 2 is a sub-flow diagram showing an embodiment of a category classification procedure in the main flow diagram shown in FIG. 1;
FIG. 3 is a subflow diagram showing a continuation of the subflow diagram shown in FIG. 3;
4 is a block diagram showing an example of an apparatus for carrying out the data demodulation method for magnetic recording data according to the present invention shown in FIG. 1; FIG.
FIG. 5 is a diagram showing speed (frequency) data between magnetic flux reversals.
FIG. 6 is a schematic diagram showing an example of a category classification procedure.
FIG. 7 is a diagram showing frequency curves after category classification.
8 is a diagram after data supplementation is performed on the frequency curve shown in FIG.
9 is a diagram obtained by smoothing the frequency curve shown in FIG.
10 is a diagram in which a threshold curve is obtained from the frequency curve shown in FIG.
11 is a diagram showing a state in which the threshold curve shown in FIG. 10 is set.
FIG. 12 is a diagram showing a magnetic flux reversal frequency in which a portion that has been erroneously read in a conventional manner is enlarged.
FIG. 13 is a block diagram showing an example of an apparatus for carrying out a conventional data demodulation method for magnetic recording data.
FIG. 14 is a timing relationship diagram illustrating an execution procedure of a conventional data demodulation method for magnetic recording data.
FIG. 15 is a schematic diagram showing a conventional misread state.
[Explanation of symbols]
11 Magnetic recording medium 12 Magnetic head 13 Amplifier 14 A / D converter 15 Memory 16 CPU

Claims (5)

A "0" signal or a "1" signal is detected based on interval data obtained by detecting a peak position in a reproduction signal of magnetic recording data written on a magnetic recording medium and measuring a time interval between adjacent peak positions. In the data demodulation method of magnetic recording data for demodulating magnetic data information consisting of:
Each of the interval data relating to the peak position of the reproduction signal is classified into three categories of “0” data, “1” data, and “gray zone” data, which is unknown.
Two smoothing curves are obtained by performing smoothing processing on the categories of the “0” data and “1” data,
By averaging these two smoothing curves, a threshold curve for dividing the “0” data and the “1” data is obtained and set,
A data demodulating method for magnetic recording data, characterized in that binarization determination of all interval data is performed using the set threshold curve. In performing the classification of the three categories, a magnetic flux reversal time Tk for each series of magnetic domains is adopted as interval data related to the peak position of the reproduction signal,
By calculating the rate of change Tk / Tk-1 between the magnetic flux reversal times Tk-1 and Tk in adjacent magnetic domains and comparing the rate of change Tk / Tk-1 with the reference value, 2. A method for demodulating magnetic recording data according to claim 1, wherein classification is performed. In determining the rate of change Tk / Tk-1 between the magnetic flux reversal times Tk-1, Tk, the frequency Vk is the reciprocal 1 / Tk-1, 1 / Tk of the magnetic flux reversal times Tk-1, Tk. -1 and Vk change rate Vk-1 / Vk,
3. The magnetic recording data according to claim 2, wherein the three categories are classified by comparing the rate of change Vk-1 / Vk of the frequencies Vk-1 and Vk with a reference value. Demodulation method. By classifying the three categories, two frequency curves corresponding to “0” data and “1” data are obtained,
4. The data demodulating method for magnetic recording data according to claim 3, wherein two smoothing curves are obtained by smoothing each of the two frequency curves. By classifying the three categories, two frequency curves corresponding to “0” data and “1” data are obtained,
Replenishment processing is performed so that the number of data in each of the two frequency curves is almost the same,
5. The data demodulation of magnetic recording data according to claim 4, wherein smoothing processing by moving average is performed on the two frequency curves subjected to the replenishment processing to obtain two smoothing curves. Method.

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