JP2000306202A - Design and development system of magnetic recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to simply calculate a SNR margin by providing this design and development system of a magnetic recording device with an arithmetic calculating means of a total SNR calculated from an electromagnetic conversion characteristic parameter, an arithmetic calculating means of a necessary SNR calculated by the electromagnetic conversion parameter and a signal processing method, and an SNR margin calculating means for calculating a difference between the total SNR calculating means and the necessary SNR calculating means. SOLUTION: A necessary SNR function formula and a total SNR calculating formula are stored in a storage means 22 beforehand. An electromagnetic parameter actually measured by using a magnetic head and a magnetic disk medium is transmitted from an input device 1 to an arithmetic expression analyzing device 21. The arithmetic expression analyzing device 21 calculates the total SNR by the total SNR calculating means 25, and calculates the necessary SNR by the necessary SNR calculating means 26. Next, the device 21 calculates a difference between the total SNR and the necessary SNR by an SNR margin calculating means 27, and judges and examines the quality of the result from the SNR margin. The device outputs the result of the examination to an output device 3 and stores it in an external storage device 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a design and development system for a magnetic recording apparatus, and more particularly to an SNR (signal to noise) corresponding to a read / write margin (R / W margin) between a magnetic head and a magnetic disk medium.
aio) A design and development system for a magnetic recording apparatus that enables a margin to be easily calculated, reduces the number of steps required to develop the magnetic recording apparatus, and increases development efficiency.

[0002]

2. Description of the Related Art In recent years, with the spread of PCs and EWS and the progress of multimedia, magnetic recording devices have been steadily increasing in capacity, and the recording density has been improved at a threatening speed of 60% per year. Is planned. For this reason, a higher and higher recording density is required year by year, and a head (hereinafter referred to as an MR head) using a MR element (magnetoresistive element) as a reproducing element and a PRML (partial response) are used.
Attempts have been made to introduce and realize new technologies such as e maximum (like maximum) signal processing technology.

In general, the performance of the entire magnetic recording apparatus used by connecting to a host of an information processing system largely depends on a magnetic head and a magnetic disk medium which are main components of the apparatus. The main factor that determines the performance of a magnetic recording device is the waveform quality when recording / reproducing (read / write: R / W) on a magnetic disk medium by a magnetic head.

Therefore, when developing and designing a magnetic recording device, it is common to measure and evaluate an index indicating waveform quality called an electromagnetic conversion characteristic parameter as shown in FIG. Regarding the measurement of the electromagnetic conversion characteristic parameter, it can be easily measured as inspection data when the manufacture of the magnetic head and the magnetic disk medium is completed.

Here, the electromagnetic conversion characteristic parameters will be described with reference to FIG. 9 which shows a schematic diagram of a waveform recorded on a magnetic disk medium by an MR head.

Referring to FIG. 9, the solitary wave output is an index indicating the magnitude of the amplitude of a reproduced waveform of a magnetic recording signal in a state where there is no waveform interference. In particular, in an MR head, as shown in FIG. Positive solitary wave (positive pull)
se) and negative solitary wave (negative pulse)
Since the magnitudes of the amplitudes are different from each other, the total solitary wave output is expressed as follows.

Viso = Vp + Vn (1) The waveform asymmetry refers to the difference in the magnitude of the amplitude, and is expressed by the following equation.

Asy = {(Vp−Vn) / (Vp + Vn)} × 100 (2) The half-width of an isolated wave is a time width of 50% of the output of an isolated waveform, and is the same as the amplitude of a reproduced waveform. In the head, since the half widths of the positive and negative solitary waves are different, they are expressed as follows.

Pw50 = (Pw50p + Pw50n) / 2 (3) However, both the magnetic head and the magnetic disk medium have manufacturing variations, and as a result, they have a fate that their characteristics also vary. In other words, evaluation using only the electromagnetic conversion characteristic parameters can determine sufficient conditions for the performance of the entire apparatus, but cannot accurately determine the degree of the quality of the apparatus.

Therefore, an index focusing on the margin of recording / reproduction (hereinafter, referred to as an R / W margin) for an error is calculated by a simulation calculation using the measurement result of the electromagnetic conversion characteristic parameter, and the index is calculated based on the performance of the entire apparatus. As an evaluation, or an error is likely to occur and stress is applied, for example, a magnetic head is intentionally off-tracked to cause an error easily, or an error threshold is intentionally changed to easily cause an error. Or let me
A device has been devised so that the R / W margin can be measured in a short time.

In Japanese Patent Application Laid-Open No. 9-180373, a phase R / W margin in which a phase is stressed and an output level R / W margin in which an output level detection threshold is stressed are measured in a short time. A technique for finding an optimum value is disclosed.

However, in the PRML signal processing method, which is a new technology, it is impossible to apply a stress to the phase, so that it is difficult to measure the R / W margin in a short time, and it takes an enormous amount of time and labor. Is required.

On the other hand, in the MR head, since the number of parameters of the electromagnetic conversion characteristics is larger than that of a conventional thin film head / MIG (metal ingap) head, there is a problem that control becomes complicated. Further, although the electromagnetic conversion characteristics of the individual magnetic heads are remarkably improved, there is a problem that the variation is much larger than that of the conventional thin film head.

Therefore, if an evaluation is to be performed using computer simulation instead of the actually measured R / W margin, the evaluation must be performed for all combinations of the electromagnetic conversion characteristic parameters, and this method also requires an enormous amount of time. There is.

[0015]

The above-described conventional design and development method of a magnetic recording apparatus cannot stress the phase and easily cause an error when using the PRML signal processing technique. Therefore, it is not possible to measure the R / W margin in a short time, it takes an enormous amount of time, and when an MR head is used, the number of parameters of the electromagnetic conversion characteristics increases and control becomes complicated. At the same time, there is a large variation in the electromagnetic conversion characteristics of the individual magnetic heads, and when performing evaluation using computer simulation, it has to be performed for all combinations of the electromagnetic conversion characteristic parameters, which takes an enormous amount of time.

An object of the present invention is to eliminate the need for a time-consuming computer simulation for each measured electromagnetic conversion characteristic and to perform an enormous time-consuming measurement / evaluation of the R / W margin without performing R / W measurement. It is an object of the present invention to provide a design and development system for a magnetic recording apparatus capable of easily calculating an SNR margin equivalent to a margin.

[0017]

According to the present invention, there is provided a design and development system for a magnetic recording apparatus, comprising: an input device; a data processing device operating under program control; and a result connected to the data processing device and operated by the data processing device. And an external storage device connected to the data processing device and storing a result calculated by the data processing device. The data processing device includes an arithmetic expression analysis unit, a storage unit for storing the arithmetic expression, A system controller connected to the expression analysis means and the storage means for controlling the operation expression analysis means and the storage means, wherein the operation expression analysis means is a total SNR operation means calculated from electromagnetic conversion characteristic parameters of the magnetic recording device Required SNR calculating means calculated by the electromagnetic conversion characteristic parameter and the signal processing method, total SNR calculating means and required SNR And having a SNR margin calculating means for calculating a difference between the calculation means.

The total SNR calculating means has means for calculating a logarithm of a ratio of a signal amplitude of a solitary wave output of a magnetic recording waveform to a noise composed of noise of a magnetic disk medium and amplifier noise of a magnetic head. And

The amplifier noise of the magnetic head is characterized by comprising voltage noise and current noise.

The required SNR calculating means is characterized in that it has means for calculating a normalized half value width in which the solitary wave half value width is normalized and the waveform asymmetry of the positive and negative solitary waves.

The normalized half width is calculated by dividing the half width of the solitary wave of the magnetic recording waveform by the magnetization reversal time.

The waveform asymmetry is characterized in that it is calculated by dividing the difference between the amplitudes of the positive and negative solitary waves by the sum of the amplitudes of the positive and negative solitary waves.

The electromagnetic conversion characteristic parameters include solitary wave output, waveform asymmetry, solitary wave half width, noise of a magnetic disk medium, amplifier noise of a magnetic head, magnetic head resistance, magnetic disk medium SNR, Overwrite loss.

The signal processing method is PR4ML (parti
al response class4 maximu
(mlikelihood).

The total SNR calculating means has means for calculating the logarithm of the ratio of the output signal amplitude at the time of overwriting and the noise composed of the magnetic disk medium noise and the magnetic head amplifier noise.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a design and development system for a magnetic recording apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a first embodiment of a design and development system for a magnetic recording apparatus according to the present invention.

Referring to FIG. 1, a design and development system 30 for a magnetic recording device includes an input device 1, a data processing device 2 that operates under program control, and a result calculated by the data processing device 2 connected to the data processing device 2. And an external storage device 4 that is connected to the data processing device 2 and stores a result calculated by the data processing device 2. The data processing device 2 includes an arithmetic expression analysis unit 2.
1, storage means 22 for storing the arithmetic expression, and arithmetic expression analysis means 21 connected to the arithmetic expression analysis means 21 and the storage means 22
System controller (M
PU) 23, and the arithmetic expression analyzing means 21 includes a total SNR calculating means 25 calculated from the electromagnetic conversion characteristic parameters, a required SNR calculating means 26 calculated from the electromagnetic conversion characteristic parameters and the signal processing method, And SNR margin calculating means 27.

Next, the operation of the magnetic recording apparatus design and development system 30 configured as described above will be described.

FIG. 2 is a flowchart showing the operation of the design and development system 30 for a magnetic recording apparatus.

Referring to FIG. 2, first, in stage 1, a new design and development system 3 of the magnetic recording apparatus of the present invention is provided.
It is determined whether 0 is to be constructed or not. If YES, the process branches to stage 2; if NO, the process branches to stage 3.

In the stage 3, the necessary SNR calculating means 26
It is determined whether or not it is necessary to reconstruct the necessary SNR calculation formula described later, which is applied in (1). If YES, the process branches to stage 4, and if NO, the process branches to stage 5.

In stage 2, how the bit error rate (hereinafter referred to as BER) changes when the SNR is changed is examined in advance by computer simulation under various conditions. However, every time a magnetic recording device is designed and developed (each time a specification is changed), it is not advisable in terms of design and development man-hours to perform a computer simulation based on this, so standardize it so that it is as common as possible. It is more convenient to do so. Therefore, in the present embodiment, computer simulation is performed using a general Lorentz waveform (referred to as y) as a model of a magnetic recording waveform (isolated waveform).

By using a simple superposition (superposition) calculation, the Lorentz waveform can easily represent a magnetic recording waveform corresponding to a data sequence in an actual magnetic recording apparatus. In the Lorentz waveform, the waveform amplitude can be made asymmetric using the parameter of the second-order distortion (D). That is, a waveform having asymmetry, such as a reproduction waveform of an MR head, can be well described.

Here, a function formula of a general Lorentz waveform is shown below.

Y (t) = Viso / {1+ (2t / Pw50) ² } (4) where t is a time component.

When the superimposed Lorentz waveform is z (t), an asymmetric waveform can be expressed as follows.

Z (t) = z (t) + z (t) ² × D (5) where D indicates waveform asymmetry (D = Asy).

On the other hand, the solitary wave half width is also standardized so that each device can be used in common as much as possible. In the present embodiment, the normalized half-width (K) is determined by a conversion formula divided by the magnetization reversal time (Tc) inside the channel, and is based on the difference in the ratio (code rate) between the transfer rate of the user and the transfer rate inside the channel. The difference in required SNR can be eliminated. Normalized half width (K)
Is represented by the following equation.

K = Pw50 / Tc (6) FIG. 3 shows the relationship between SNR and BER using the second-order distortion (D) as a parameter when the signal processing method is PR4ML and the normalized half width K = 2. An example of the computer simulation result shown is shown. Actually, it is necessary to perform the combination with various combinations of K and D other than the conditions of FIG.

Next, the stage 4 will be described in detail.

First, the relationship between BER and SNR, which are design targets for the entire magnetic recording apparatus, will be described.

The device design target BER of is generally different from that by an error correction code (ECC), further, may vary depending on the design concept, as raw bit error rate, which in the case of BER = 10 ^-6 Only R
/ W margin is checked. S shown in FIG.
First, an SNR that satisfies BER = 10 ⁻⁶ is read from a computer simulation result showing the relationship between NR and BER. Next, using the result, a required SNR expression under each condition is derived as a quadratic function expression by the least square method. SNR
FIG. 4 shows the relationship between K and K, and FIG. 5 shows the relationship between SNR and D.

Finally, based on the quadratic function, the coefficients are examined so that the required SNR can be calculated for any K and D. In the present embodiment, each coefficient can be represented as follows.

Required SNR = (− 4.446) × K + 2.095 × K^Two + 4.498 × 10 ^-3 × D^Two +23.642 (7) This is used as a necessary SNR function formula, and the required SNR calculating means 26
Apply to This required SNR function formula is
And call it whenever you want
In this case, the storage unit 22 of the data processing device 2
The above arithmetic expression is stored.

Next, in the stage 5, it is determined whether or not it is necessary to reconstruct a total SNR calculation formula described later applied by the total SNR calculation means 25, and a new total SNR calculation formula is created. In this case, or when updating the current function expression, the process branches to stage 6; otherwise, the process branches to stage 7.

Next, the total SNR in stage 6
The derivation of the arithmetic expression will be described.

The total SNR is an SNR calculated from an actually measured electromagnetic conversion characteristic parameter. In a magnetic recording device, the ratio between the signal amplitude (S) and the noise (N) is expressed as a logarithm. Is represented by the following equation.

Total SNR = 20 Log (S / N) (8) In the magnetic recording device, the signal amplitude and noise are generally calculated by the following equations.

S = Viso / 2 (9) N ² = Nm ² + Nc ² (10) In the above equation, the medium noise (Nm) can be inputted with the measured value as a parameter, and the head amplifier noise (Nc)
About voltage noise (Vn) and current noise (In)
And the following relational expression is obtained.

Nc ² = Vn ² + (In × Rmr) ² (11) where Rmr is the resistance of the magnetic head and the measured value of Nc may be used every time. Depends on the circuit that amplifies the signal from the head,
Since there is little variation, Vn and In may be fixed values.

These are applied to the total SNR calculation means 25 as a total SNR calculation formula. This total S
When the NR calculation formula can be called and calculated at any time as a design and development system, the total SNR calculation formula is stored in the storage unit 22 of the data processing device 2.

Next, at the stage 7, the electromagnetic conversion characteristic parameters shown in FIG. 8 are measured using the actual magnetic head and magnetic disk medium. In addition, actual measurement may be performed under arbitrary conditions, or shipping inspection data of a magnetic head or a magnetic disk medium may be used.

Next, in the stage 8, the electromagnetic conversion characteristic parameters obtained in the stage 7 are transmitted to the data processing device 21 using the input device 1, and the total SNR calculating means 25 of the data processing device 21 outputs
Is calculated.

After calculating the total SNR, the stage 9 transmits the electromagnetic conversion characteristic parameters obtained by the stage 7 to the data processing device 21 using the input device 1 as in the stage 8, and Required SNR
The calculation means 26 calculates the required SNR.

Next, in the stage 10, the SNR margin calculating means 27 calculates the difference between the total SNR calculated in the stages 8 and 9 and the required SNR, and
The R margin is calculated, and the pass / fail judgment and examination are performed based on the SNR margin. As an example of the pass / fail judgment, the cause of the R / W margin loss not included in the arithmetic means is more than S / W margin loss factor.
It is determined whether the NR margin is large. For example, in the case of the above equation, R / W due to the off-track factor is used.
Since the deterioration of the margin is not included, it is determined that the combination of the magnetic head and the magnetic disk medium having the SNR margin larger than the estimated deterioration is good. Conversely, if the SNR margin is small, it is determined to be defective, and examinations such as component replacement, component specification change, measurement condition change, and design specification change are performed. The magnetic head and the magnetic disk medium may be individually examined, or some samples may be taken and examined by a statistical method. The examination result is output to the output device 3. Further, the result output to the output device 3 at an arbitrary time is stored in the external storage device 4.

Next, in the stage 11, it is determined whether or not another condition or another component should be examined according to the examination result of the stage 10.

As described above, by measuring the electromagnetic conversion characteristic parameters as shown in FIG. 8 by the operation of the stages 1 to 11, the SNR margin can be calculated, and the conventional R / W The same result as the margin can be obtained.

Incidentally, if it is desired to calculate the SNR margin at BER = 10 ^-5 , it is not necessary to re-execute the computer simulation which takes a long time and reconstruct the total SNR calculation formula. From the computer simulation results of SNR and BER under FIG. 3 and other conditions,
The SNR margin can be calculated simply by reading an SNR satisfying BER = 10 ^-5 and using the data to perform the same operation as the above-described SNR margin calculation at BER = 10 ^-5 .

Next, a comparison result between the SNR margin of the magnetic recording apparatus design and development system 30 of the present invention and the R / W margin measured by the conventional method of the magnetic recording apparatus will be described.

FIG. 6A shows the SNR margin obtained by the magnetic recording apparatus design and development system 30 of the present invention,
FIG. 11 is a diagram showing a comparison with an R / W margin measured by a conventional method.

Referring to FIG. 6A, the horizontal axis is the SNR margin obtained from the magnetic recording apparatus design and development system 30 of the present invention, and the vertical axis is the conventional R / W margin (Vi).
terbi Margin) measurement results, and the solid line in the figure shows the theoretical formula for converting the SNR margin into the R / W margin value measured by the conventional method, but the measured value is slightly different from the theoretical formula curve. Is out, but S
It can be said that the NR margin relatively well agrees with the theoretical value that can be calculated from the actually measured R / W margin of the magnetic recording apparatus.

FIG. 6B is a plot of the results of measuring the electromagnetic conversion characteristic parameters during the design and development of the magnetic recording apparatus. The measurement conditions were as follows: the magnetic disk medium was fixed to a specific sheet, and the magnetic head measured 40 samples, and plotted the solitary wave output (Viso) and the solitary wave half width (Pw50) among the measured data. ing. The horizontal axis represents the solitary wave half-width and the vertical axis represents the solitary wave output, and the broken line indicates the standard value of Pw50 and the standard value of Viso which have been used in the magnetic storage device until now. Further, the result calculated by the design and development system 30 of the magnetic recording apparatus of the present invention used in this magnetic recording apparatus is represented by a solid line.

Referring to FIG. 6B, there are 14 magnetic heads satisfying the conventional standard values in an area surrounded by a broken line having a narrow Pw50 and a large Viso. Therefore, the yield is 35.0%. However, R /
When examined from the viewpoint of a magnetic head that can be used as an apparatus from a W margin, the magnetic head is located in the upper right area from the solid line, 30 samples are non-defective, and the yield is 75.0%. In other words, it can be seen that the conventional method using the standard value determines that even a usable magnetic head is defective.

Next, a description will be given of a second embodiment of the design and development system for a magnetic recording apparatus according to the present invention.

In the second embodiment, in order to improve the accuracy of the magnetic recording apparatus design and development system 30 of the present invention, a PR
In the 4ML signal processing method, the loss due to O / W (overwrite) is also taken into consideration. The difference from the first embodiment is that the arithmetic expression of the total SNR is
In the first embodiment, the solitary wave amplitude (Vis
o) is used, whereas O / W is used in the second embodiment.
Only the operation is performed using the output amplitude (Vow) included in the first embodiment, and the other points are the same as those in the first embodiment. Therefore, different points will be mainly described below.

First, the loss due to O / W will be described with reference to FIG. 7 showing an isolated solitary waveform after passing through an ideal PR4ML equalizer.

As shown by a circle in FIG. 7, the ideal PR4
In the transfer function of ML, the sampling point is ± 1 or 0
This is a signal system in which only three values come out. Also, it does not come out as a sampling value of the signal system,
It has been found that the peak value as an analog waveform is 1.29 times the sampling value 1.

Actually, there are various noises, and the signal waveform is
When the data is passed through the R4ML transfer function, the sampling point becomes as indicated by the symbol ■, and a variation appears with respect to the theoretical value. Among them, the variation due to O / W, that is, the loss due to O / W is derived, it can be considered that the output amplitude decreases due to the O / W and affects the total SNR. In other words, the loss due to O / W applied to the entire apparatus may be determined by examining how much the signal amplitude is reduced by the O / W. In the case where the peak, which is the maximum value of the output amplitude, is superimposed on the remaining writing sampling point. , The worst value, and the peak value is 1.29 times the sampling value, so it can be regarded as a decrease linked to that value.

Therefore, the output amplitude including the O / W (Vow)
Can be derived by the following relational expression.

Vow = Viso × (1-1.29 × 10 ^{(O / W / 20)} ) (12) Next, in stage 5 of the flowchart shown in FIG. 2, restructuring of the total SNR calculation expression is selected. By incorporating the above considerations in the stage 6, a design and development system considering O / W can be constructed. That is, total S
In the derivation of the NR operation formula, by using the output amplitude (Vow) including the O / W instead of using the solitary wave amplitude (Viso) as the signal amplitude (S), a design in which the loss due to the O / W is also considered. It can be a development system.

In the first and second embodiments, the PR4ML processing method has been described as a signal processing method. However, the EPR4ML (expand partia)
lresponse class4 maximum
Likeelihood), EEPR4ML (expan
d expand partial response
class4 maximum likelihood
d), for each signal processing method of peak detection, the arithmetic expression analysis means 21 of the data processing device 2 also executes S
It is needless to say that the calculation of the NR margin is possible and is included in the present invention.

[0073]

As described above, the system for designing and developing a magnetic recording apparatus according to the present invention does not require the measurement of the R / W margin, which has conventionally required a great deal of time and effort, without using a magnetic head and a magnetic disk medium. It is possible to easily calculate the SNR margin corresponding to the recording / reproducing margin with
This has the effect of reducing development man-hours for the magnetic recording device and increasing development efficiency.

In addition, the quality of the magnetic head and the recording medium, which are the components, can be determined with high accuracy, and the yield and the reliability can be improved.

Further, since the function formula of the required SNR is standardized, there is an effect that it can be commonly used in various magnetic recording devices.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing an embodiment of a design and development system for a magnetic recording apparatus according to the present invention.

FIG. 2 is a flowchart showing the operation of the design and development system for a magnetic recording apparatus according to the present invention.

FIG. 3 SNR and BER by computer simulation
FIG.

FIG. 4 is a diagram showing a relationship between SNR and K.

FIG. 5 is a diagram showing a relationship between SNR and D.

FIG. 6A is a diagram showing a comparison between an SNR margin obtained by a design and development system for a magnetic recording apparatus according to the present invention and an R / W margin measured by a conventional method.
(B) is a figure which shows the result of having measured the electromagnetic conversion characteristic parameter.

FIG. 7 is a diagram showing a solitary wave waveform after passing through a PR4ML equalizer.

FIG. 8 is a diagram showing electromagnetic conversion characteristic parameters.

FIG. 9 shows a schematic diagram of a waveform recorded on a magnetic disk medium by an MR head.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 input device 2 data processing device 3 output device 4 external storage device 21 arithmetic expression analysis means 22 storage means 23 system controller (MPU) 25 total SNR calculation means 26 required SNR calculation means 27 SNR margin calculation means 30 design and development of magnetic recording device system

Claims (9)

[Claims] 1. An input device, a data processing device operated by program control, an output device connected to the data processing device and outputting a result calculated by the data processing device, and an output device connected to the data processing device. An external storage device that stores a result calculated by a processing device, wherein the data processing device is connected to the arithmetic expression analysis device, a storage device that stores an arithmetic expression, and the arithmetic expression analysis device and the storage device. And a system controller for controlling the arithmetic expression analysis means and the storage means, wherein the arithmetic expression analysis means comprises: a total SNR arithmetic means calculated from an electromagnetic conversion characteristic parameter of the magnetic recording device; A required SNR calculating means calculated by a parameter and a signal processing method, the total SNR calculating means and the required SNR calculating means A design and development system for a magnetic recording apparatus, comprising: an SNR margin calculating means for calculating a difference from a step. 2. The total SNR calculating means includes means for calculating a logarithm of a ratio between a signal amplitude of a solitary wave output of a magnetic recording waveform and a noise composed of noise of a magnetic disk medium and amplifier noise of a magnetic head. 2. The method according to claim 1, wherein
The design and development system of the magnetic recording device described in the above. 3. The magnetic head according to claim 2, wherein the amplifier noise comprises voltage noise and current noise.
The design and development system of the magnetic recording device described in the above. 4. The apparatus according to claim 1, wherein the required SNR calculating means includes means for calculating a normalized half-width obtained by normalizing the half-width of the isolated wave and a waveform asymmetry of the positive and negative solitary waves. Design and development system for magnetic recording devices. 5. The design and development system for a magnetic recording apparatus according to claim 4, wherein said normalized half width is calculated by dividing a half width of a solitary wave of a magnetic recording waveform by a magnetization reversal time. 6. The magnetic recording apparatus according to claim 4, wherein the waveform asymmetry is calculated by dividing a difference between the amplitudes of the positive and negative solitary waves by a sum of the amplitudes of the positive and negative solitary waves. Design and development system. 7. The electromagnetic conversion characteristic parameters include the solitary wave output, the waveform asymmetry, the solitary wave half-width, noise of the magnetic disk medium, amplifier noise of the magnetic head, and resistance of the magnetic head. And the magnetic disk medium S
2. The design and development system for a magnetic recording apparatus according to claim 1, wherein the system comprises NR and overwrite loss. 8. The system according to claim 1, wherein the signal processing system is PR4ML. 9. The total SNR calculating means includes means for calculating a logarithm of an output signal amplitude at the time of overwriting and a ratio of noise composed of noise of the magnetic disk medium and amplifier noise of the magnetic head. 2. The design and development system for a magnetic recording apparatus according to claim 1, wherein: