JPH08297924A - Method and device for recording digital signal, media for recording digital signal, and method and device for transmitting digital signal - Google Patents

Abstract

PURPOSE: To eliminate the need of an equalization circuit from a reproducing device side by obtaining signals having an excellent waveform and containing less jitters as the output signal of an optical pickup for reproduction regardless of the relative speed. CONSTITUTION: A G(fs) converter 31 gives an ideal spatial frequency characteristic G(fs) to an inputted bit train composed of recording NRZI signals. An EQ(fs) converter 32 gives the equalizing frequency characteristic EQ(fs) required on the reproduction side to the output signal of the converter 31. In addition, a saturation amplifier 24 generates a pre-jittered recording signals by intensifying a high-frequency band by saturating and amplifying the output of the converter 32 and the recording signals are recorded on an optical disk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal recording method and apparatus effective for use in a recording apparatus for recording digital data on an optical disc, and a recording medium therefor, and applied to a digital signal transmission method and apparatus. Even so, it is a useful invention.

[0002]

2. Description of the Related Art For example, the types of optical discs include digital audio discs on which audio signals are recorded,
There are digital video discs that record audio and video signals. A reproducing device for reproducing these optical disks has a rotary servo unit for rotationally driving the disk, and an optical pickup for irradiating a recording surface of the disk with a laser beam and detecting reflected light to read a recording signal. The modulated signal output from the optical pickup is first input to the equalizing circuit and waveform equalized. Then, the waveform-equalized signal is guided to the demodulation circuit.

[0003]

As described above, the disc reproducing apparatus usually includes an equalizing circuit for equalizing the picked up signal. But this equalization circuit
It is expensive in price, and good equalization characteristics are not always guaranteed. It is possible that its characteristics may change over time.

Therefore, an object of the present invention is to provide a digital signal recording method and apparatus and a recording medium thereof which can realize the elimination of the equalizer circuit on the reproducing apparatus side.

Further, according to the present invention, as an output signal of the reproducing optical pickup, a signal having a good waveform with little jitter is provided.
It is an object of the present invention to provide a digital signal recording method and device and a recording medium thereof that can be obtained regardless of the relative reading speed, and that can eliminate the need for an equalizing circuit on the reproducing device side. is there.

It is another object of the present invention to provide a digital signal transmission method and apparatus which can obtain good characteristics as demodulated output characteristics of a digitally transmitted digital signal.

[0007]

In order to achieve the above-mentioned object, the recording or transmitting method of the present invention comprises a first rectangular wave.
To obtain a second digital signal sequence in which a predetermined ideal frequency characteristic is added to the second digital signal sequence, and the second digital signal sequence is further provided with a reproduction side or reception side equalization characteristic. A signal is obtained, a fourth digital signal sequence is obtained by saturation amplification of the third digital signal, and the fourth digital signal sequence is recorded or transmitted.

In order to achieve the above object, the recording or transmitting apparatus of the present invention is a means for obtaining a second digital signal train in which a predetermined ideal frequency characteristic is given to the first digital signal train of a square wave. And in this second digital signal string,
Further, means for obtaining a third digital signal to which equalization characteristics on the reproducing side or the receiving side are given, means for obtaining a fourth digital signal sequence obtained by saturation amplification of this third digital signal, and this fourth digital signal It has means for recording or transmitting rows.

In order to achieve the above object, in the recording or transmitting method of the present invention, the bit interval is Pw, and the transition point interval between bit 0 and bit 1 is n × Pw to m × Pw (however, n,
a first step of generating a first signal in which the information of the bit transition point interval is maintained by giving a predetermined ideal ideal frequency characteristic to an input bit string in which m is an integer n <m); A second step of generating a second signal by giving an equalization frequency characteristic to the output signal from the reproducing pickup (or high frequency receiving section) to the first signal; and saturating the second signal. A third step of amplifying and converting to a bit string.

In order to achieve the above object, in the recording or transmitting apparatus of the present invention, the bit interval is Pw, and the transition point interval between bit 0 and bit 1 is n × Pw to m × Pw (however,
a first conversion means for generating a first signal in which the information of the bit transition point interval is maintained by giving an ideal predetermined ideal frequency characteristic to an input bit string where n and m are n <m) A second conversion for generating a second signal by giving an equalization frequency characteristic to the output signal from the reproducing pickup (or high frequency receiving section) to the first signal output from the first conversion means. And a third conversion means for saturation-amplifying the second signal output from the second conversion means and converting the second signal into a bit string.

According to the present invention, when used as a signal recording device for a disc, the recording pit train on the disc is reproduced by the reproduction signal frequency spectrum characteristic and the reproduction signal final spectrum characteristic whose desired frequency characteristics are desired ideal. The signal is equalized to a characteristic provided with a compensation characteristic for preventing deterioration of the signal, and saturated recording is performed. That is, the recording signal has ideal equalized jitter. As a result,
When the reproducing device reproduces the above-mentioned recorded signal, it is possible to obtain a good reproduced signal with less jitter without using a complicated equalizing circuit due to the effect. This also applies to the transmission system, and the received signal has a good waveform.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, a technique as a premise of the present invention will be described with reference to FIGS.

FIG. 1 shows a disk recording / reproducing system.
A modulation signal for recording is supplied to the input terminal 11. This modulated signal is an NRZI obtained by modulating a digital signal.
(Non-return-to-zero-interleaved) signal. This NRZI signal is input to the saturation amplifier 13 of the exposure device 12, is saturated and amplified, and is shaped into a square wave signal. The square wave signal output from the saturation amplifier 13 is input to the optical modulator 14 and converted into light, and the recording surface of the optical disc 15 is irradiated with the laser beam as a medium. The optical disc 15 is a phase change type or magneto-optical change type information recordable optical disc.

The recorded information recorded on the optical disk 15 is read by a pickup (not shown) using a laser. The read signal output from the pickup is waveform-equalized by the reproduction equalizer 16. The output of the equalizer 16 is input to the level determiner 17, is compared with the slice level, and is output to the output terminal 18 as a square wave signal.

Now, assuming a case where an ideal single-cycle rectangular bit having no jitter is recorded on the optical disk 15, this is taken by an optical pickup 12 having a laser wavelength λ and an objective lens numerical aperture NA. The maximum readable spatial frequency that can be read correctly is fsmax = 2NA
/ Λ.

FIG. 2 shows the reading characteristics of the optical pickup 12 at each spatial frequency. This depends on the spatial transfer frequency characteristic 0TF (fs) existing in the optical system. Due to this characteristic, the reading characteristic at each spatial frequency by the optical pickup 12 is a characteristic in which the amplitude of the reproduced signal is linearly attenuated from the low spatial frequency to the high spatial frequency with a constant group delay. .

Here, when the relative reading speed between the optical disk 15 and the optical pickup is V, the frequency characteristic of the signal output from the optical pickup is represented by V × OTF (fs).

The maximum reproduction frequency fmax is fma
It is represented by x = V × fsmax = V × (2NA / λ). For example, when λ = 635 nm and ΝA = 0.6, fs
Since max = 2NA / λ, the maximum readable spatial frequency is fsmax = 1890 [pieces / mm]. And
The recording cycle of the readable square pit array is 529 nm.

At this time, the maximum reproduction output is obtained when the duty is 50%, that is, when the length of the square pit and the length of the non-pit portion are both 265 nm. The maximum reproduction frequency fmax output when V = 3.6 m / s is fmax = 6.8 MHz.

Now, an ideal rectangular pit string having a non-single period is recorded on the optical disc, and the pit length and the non-pit length are both Pw (the minimum bit interval between adjacent bits).
When the shortest pit length and the shortest non-pit length are both n × Pw (length of 0 or 1 consecutive), the zero cross point of the reproduction signal is exactly m × Pw interval (m
The ideal spatial frequency characteristic G (fs) for satisfying> n) is
As shown in FIG. 3, G (fs) = 1 (however, fs ≦ (1-k) fsc range) G (fs) = (1/2) + (1/2) cos [(π / 2) + (π / 4) × {(fs-f
sc) / (k × fsc)} {where (1-k) fsc <fs <(1 + k) fsc range} G (fs) = 0 (where fs ≧ (1 + k) fsc range) is given. Here, fsc = 1 / (2n × Ρw) k = (fsmax / fsc) −1 (however, fsmax
<Range of 2 fsc) k = 1 (however, fsmax
≧ 2 fsc range).

Such an ideal spatial frequency characteristic G (fs)
Is said to have a consign roll-off characteristic with a cutoff frequency of fsc = 1 / (2n × Pw) and (k × 100)%.

Therefore, when the required spatial equalization frequency characteristic EQ (fs) is shown for the spatial transfer frequency characteristic 0TF (fs) of the optical pickup which is the optical system, EQ (fs) = G (fs) / OTF ( fs) ... (1) is given. FIG. 4 shows typical characteristics of the above formula (1).

Returning to FIG. 1, the description will be continued. The equalizer 16 uses the spatial equalization frequency characteristic EQ (f
s), but since the relative reading speed V between the optical disk and the optical pickup is related, it is actually V
The characteristic of × EQ (fs) is required.

That is, the characteristic of V × EQ (fs) = V × [G (fs) / OTF (fs)] (2) is required. This is an equalizer 16 for playback
Means that the reproduction signal of the optical pickup is equalized by using the equalization frequency characteristic (2) in which the element of the relative reading speed V is added to the characteristic of the equation (1).

Specifically, this means that the equalizer 16
4 means that the spatial equalization frequency characteristic EQ (fs) shown in FIG. 4 is changed according to the relative speed V. In Figure 5,
The eye pattern characteristic of the output signal when the reproduced signal from the optical pickup is not equalized is shown, and FIG. 6 shows the eye pattern characteristic of the output signal when the reproduced signal from the optical pickup is equalized. The vertical axis in FIGS. 5 and 6 is the amplitude, and the horizontal axis is the time direction.

In the reproducing system, since the spatial transfer frequency characteristic 0TF (fs) of the optical pickup and the relative reading speed V are added as factors, the frequency characteristic of the output signal when the reproduced signal of FIG. 5 is not equalized is V ×. It is represented by OTF (fs).

On the other hand, the frequency characteristic of the output signal when the reproduced signal of FIG. 6 is equalized is [V × EQ (fs)] × OTF (fs) ... (3) EQ (fs) ≠ 1. The frequency characteristic of the output signal after equalization is OTF (fs) = G (fs) /
Since it is EQ (fs), the expression (3) is [V × EQ (f
s)] × [G (fs) / EQ (fs)] = V × G (f
s), which is close to the ideal spatial frequency characteristic given the relative reading speed V. The characteristics of this system change depending on the relative reading speed V.

Therefore, in order to always obtain a constant frequency characteristic close to ideal, the equalization frequency characteristic of the equalizer must be changed according to the relative reading speed V. On the other hand, regarding the relative read speed V, the speed ratio during recording and reproduction is 1: 1.
Is not always reproduced at the ratio of. Depending on the type of playback device and playback mode, the recording / playback speed ratio may be 1: 4.

Therefore, in the above method, the relative reading speed V
Therefore, an equalizer that can change the equalization frequency characteristic according to the above is required. However, when the equalization frequency characteristic of the equalizer is changed according to the relative reading speed V in this way,
This type of equalizer is expensive in price, and good equalization characteristics are not always guaranteed. It is possible that its characteristics may change over time.

Therefore, in the present invention, a good signal waveform with little jitter can be obtained as an output signal of the reproducing optical pickup irrespective of the relative reading speed, and thus the equalizing circuit on the reproducing device side can be eliminated. The present invention provides a recording equalization apparatus and method, and a disk recording apparatus and method capable of performing the same.

The embodiments of the present invention will be specifically described below. FIG. 7 is a diagram showing the configuration of a disc recording / reproducing system including a recording equalizer according to an embodiment of the present invention.

A modulation signal for recording is supplied to the input terminal 21. This modulation signal is an NRZI signal obtained by modulating a digital signal, for example, a signal modulated by the 8-16 modulation method. In this signal, the bit interval is Pw, and the transition point interval between bit 0 and bit 1 is n × Pw-
The input bit string is m × Pw (where n and m are integers satisfying n <m), and the signals are n = 3 and m = 11.

The NRZI signal is first input to the recording equalizer 22 which constitutes the essential part of the present invention. The recording equalizer 22 will be described later. The modulated signal output from the recording equalizer 22 is intentionally provided with jitter.

The modulated signal to which the jitter is added is input to the saturation amplifier 24 of the exposure device 23, is saturated and amplified, and is shaped into a square wave signal. The square wave signal output from the saturation amplifier 24 is input to the optical modulator 25, is optically converted, and is irradiated onto the recording surface of the optical disc 26 using a laser beam as a medium. The optical disc 26 is a pit formation type, phase change type or magneto-optical change type information recordable optical disc.

The recorded information recorded on the optical disk 26 is read by a pickup (not shown) using a laser. The read signal output from the pickup is input to the level determiner 27, is compared with the slice level, and is output to the output terminal 28 as a square wave signal.

The recording equalizer 22 will be described. FIG. 8 is a block diagram showing an internal configuration of the recording equalizer 22. As shown in the figure, the recording equalizer 22 includes a G (fs) conversion unit 31 that gives an ideal spatial frequency characteristic G (fs) to an input bit string that is a recording NRZI signal, and a G (fs) converter 31. The output signal is provided with an EQ (fs) equalization frequency characteristic of the equation (1), and an EQ (fs) conversion section 32 for generating an equalization signal for recording, and a main part thereof is configured.

FIG. 9 shows a concrete hardware configuration of the recording equalizer 22. Recording equalizer 22
Is a delay line, a multiplier group that multiplies the input and output of each delay unit by predetermined coefficients c0, cl, ..., cn, and an adder group that sequentially adds the multiplication results of each multiplier. It is configured. That is, a plurality of delay devices D are connected to the input terminal 21.
Are connected in series. The signal at the input terminal 21 and the output signal from each delay device D are multiplied by the coefficients c0 to cn by the multiplier M, respectively. The output of the multiplier M is added by the adder A and is led to the output terminal.

Next, the operation of the recording equalizer 22 will be described with reference to the signal waveforms of FIGS. First, as a first step, by applying a frequency characteristic of G (fs) to the input bit string, a signal having the eye pattern characteristic shown in FIG. 10 can be generated. Here, it is assumed that the signal shown in FIG. 10 is saturated and amplified. That is, obtaining the saturation-amplified output is to greatly amplify the signal in FIG. 10 in the amplitude direction, slice the levels on the positive side and the negative side, and extract the middle in the amplitude direction.

Then, the waveform characteristic is as shown in FIG. When the bit string signal thus obtained is recorded on the optical disc, this recording signal is the same as the recording when EQ (fs) = 1 (no recording equalization). That is, the recording frequency characteristic is flat when the G (fs) frequency characteristic is added to the input bit string.

On the other hand, in this system, after the completion of the first stage, as a second stage, the equalization frequency characteristic EQ (fs) shown in the equation (1) is added to the signal having the characteristic shown in FIG. As a result, a recording equalization signal in which the high frequency band having the characteristics shown in FIG. 12 is enhanced is generated.

When this recording equalized signal is saturation-amplified, FIG.
As shown in the characteristic of No. 3, the signal waveform has a jitter in the time axis direction. That is, a signal intentionally containing jitter is generated, and this signal is used for recording.

When the bit string signal thus obtained is recorded on the optical disk, the jitter in the time axis direction contained in the bit string signal is reflected in the recording pit length on the optical disk, and the equalization frequency characteristic is given to the recording pit string. To be done.

When reproducing the optical disc in which the pit string having the equalized frequency characteristic as described above is recorded, FIG.
As shown in (1), it is possible to obtain a good signal waveform with little jitter regardless of the relative reading speed V as the output signal of the optical pickup. This eliminates the need for an equalizer on the playback device side, which can contribute to simplification of the configuration of the playback device. Further, if the equalizer is not required on the reproducing device side, it is also effective in reducing the price. Furthermore, if the equalizer is not required, it is not necessary to guarantee the characteristics of the equalizer or worry about the characteristic deviation with time.

In this embodiment, the bit string signal is G
The G (fs) conversion unit 31 and the EQ giving the characteristic of (fs)
Although the EQ (fs) conversion unit 32 that gives the equalized frequency characteristic of (fs) is separately provided, EQ (fs) is added to G (fs).
Each converter 3 of this embodiment is a converter that gives a characteristic multiplied by
Instead of 1, 32, a single unit may be provided.

The reproducing apparatus may be configured such that, on the reproducing side, the reproducing path including the equalizer 29 and the reproducing path having no equalizer can be switched. The reproduction path including the equalizer is effectively used when reproducing a conventional optical disc. The playback path without an equalizer is
It is used when reproducing an optical disc on which information having equalized frequency characteristics is recorded as described above.

In the above embodiment, the example in which the present invention is applied to the recording / reproducing system of the optical disc has been described. However, according to the present invention, a recording system for a magnetic disc of a digital signal,
Of course, it can be applied to a recording system of a magnetic tape.
In this case, the above-mentioned space transfer frequency characteristic 0TF (f
s) is replaced by the frequency characteristic of the magnetic head.

Of course, the present invention can also be applied to a digital signal transmission and reception system. In this case, the above-mentioned spatial transfer frequency characteristic 0TF (fs) is
It is replaced with the frequency characteristic up to the input part of the antenna and the high frequency receiving part.

FIG. 15 shows a recording system for recording digital data on the magnetic disk 56 and a reproducing system for reproducing digital data from the magnetic disk 56. The digitally modulated data is equalized by the equalizer 52 with the equalization characteristic that is conventionally equalized on the reproducing side, and then input to the saturation amplifier 53. The output (square wave signal) of the saturation amplifier 53 is converted into a current by the output circuit 54 and the magnetic head 55 is converted.
Is supplied to. As a result, the high frequency component of the square wave is equalized and recorded on the magnetic disk 56. The recorded information is read by the magnetic disk 57 at the time of reproduction, but since the signal attenuation is already compensated at the time of recording, the read signal is directly input to the level determiner 58, and 0, 1
Is determined and the binarized output is led to the output terminal 59.

FIG. 16 shows an example in which the recording medium of the magnetic disk of FIG. 15 is replaced with the magnetic tape 61. Since the other parts are the same as those in the configuration of FIG. 15, the same reference numerals are given and the description thereof will be omitted.

FIG. 17 shows an example in which the present invention is applied to a system for transmitting digital data on a wireless medium.
The digitally modulated data at the input terminal 71 is equalized by the equalizer 72.
Then, after being equalized with an equalization characteristic that compensates the reception characteristic on the receiving side, it is input to the saturation amplifier 73. The output (square wave signal) of the saturation amplifier 73 is modulated by the modulator 74 so as to be a transmission signal, and the transmission signal is transmitted to the power amplifier 75.
It is amplified by and is supplied to the antenna 76. On the receiving side, the signal received by the receiving antenna 77 is input to the receiver 78 and guided to the demodulator 79. As a result, it is possible to obtain a signal before modulation on the transmission side. The output of the demodulator 79 is input to the level determiner 80 and restored to digital modulation data on the transmission side.

[0051]

As described above, according to the present invention, the recording pit train on the disc is provided with the equalized frequency characteristic with respect to the output signal of the reproducing optical pickup, so that the reproducing optical pickup outputs the signal. As a result, a good signal waveform with little jitter can be obtained irrespective of the relative reading speed, and the equalizing circuit on the reproducing device side is unnecessary.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a disk recording / reproducing system which is a premise of the present invention.

FIG. 2 is a diagram showing a spatial frequency characteristic of an optical pickup.

FIG. 3 is a diagram showing ideal spatial frequency characteristics of an optical pickup.

FIG. 4 is a diagram showing a typical equalization frequency characteristic.

5 is an eye pattern characteristic diagram in the case where a pickup does not read and equalize a recording signal of the optical disc of FIG. 1. FIG.

FIG. 6 is an eye pattern characteristic diagram in the case where the recording signal of the optical disc of FIG. 1 is read and equalized by a pickup.

FIG. 7 is a diagram showing the configuration of a disk recording / reproducing system including a recording equalization circuit according to an embodiment of the present invention.

8 is a diagram showing a principle configuration of the equalizer 22 of FIG.

9 is a diagram showing a specific configuration example of the equalizer 22 of FIG.

10 is a diagram showing eye pattern characteristics of an output signal of the G (fs) converter shown in FIG.

11 is a diagram showing a signal waveform when the signal having the characteristic shown in FIG. 10 is saturated and amplified.

12 is a diagram showing a signal having the characteristic shown in FIG.
The figure which shows the eye pattern characteristic of the signal after giving Q (fs).

13 is a diagram showing a signal waveform when the signal having the characteristic shown in FIG. 12 is saturated and amplified, that is, an output signal waveform of the saturation amplifier in FIG.

14 is a diagram showing an eye pattern characteristic of an output signal when the information on the optical disc of FIG. 7 is read by a pickup.

FIG. 15 is a diagram showing another embodiment of the present invention.

FIG. 16 is a diagram showing still another embodiment of the present invention.

FIG. 17 is a diagram showing still another embodiment of the present invention.

[Explanation of symbols]

 22 ... Equalizer 24 ... Saturation amplifier 25 ... Optical modulator 26 ... Optical disk 27 ... Level determiner.

Claims (14)

[Claims] 1. A second signal obtained by adding a predetermined ideal frequency characteristic G (fs) to a binary first signal is obtained.
Signal is further added with the equalization characteristic EQ (fs) on the reproduction side to obtain a fourth digital signal sequence obtained by saturation amplification of the third signal, and the fourth digital signal sequence is obtained. A method for recording a digital signal, which comprises recording 2. The bit interval is Pw, and the transition point interval between bit 0 and bit 1 is n × Pw to m × Pw (where n and m are n <
m) is a first step of generating a first signal that maintains the information of the bit transition point interval by giving an ideal predetermined frequency characteristic to the input bit string, and with respect to the first signal. A second step of giving an equalized frequency characteristic to the output signal of the reproducing pickup to generate a second signal; and saturation amplification of the second signal to convert it into a bit string to obtain a recording signal. A method of recording a digital signal, comprising: a third step. 3. The digital signal recording method according to claim 2, wherein the recording signal is recorded on a recording medium. 4. A means for obtaining a second signal in which a predetermined frequency characteristic is added to a binary first signal, and a third signal in which an equalizing characteristic on the reproducing side is added to the second signal. Recording of a digital signal, which comprises: a means for obtaining a signal for recording, a means for obtaining a recording signal obtained by saturation amplification of the third signal, and a recording means for recording the recording signal on a recording medium. apparatus. 5. The apparatus according to claim 4, wherein the recording means records the recording signal on a recording medium such as an optical disk, a magnetic disk or a magnetic tape. Signal recorder. 6. A bit interval is Pw, and a transition point interval between bit 0 and bit 1 is n × Pw to m × Pw (where n and m are n <
a first conversion means for generating a first signal in which the information of the bit transition point interval is maintained by giving an ideal predetermined frequency characteristic to the input bit string which is m), and the first conversion means. To the first signal output by
Second conversion means for giving a equalized frequency characteristic to the output signal of the reproduction pickup to generate a second signal, and saturation amplification of the second signal output from the second conversion means for recording. A recording device for digital signals, comprising: a third converting means for converting into a signal for recording, and a recording means for recording the signal for recording on a recording medium. 7. The apparatus according to claim 6, wherein the equalized frequency characteristic is obtained by multiplying the ideal predetermined frequency characteristic by a coefficient of an inverse characteristic of the optical frequency characteristic of the reproducing optical pickup. A digital signal recording apparatus characterized by the above. 8. The apparatus according to claim 6, wherein the predetermined ideal frequency characteristic as the ideal is a k × 100% cosine roll-off characteristic (where 0 ≦ k) with a cutoff frequency of 1 / (2n × Pw). <1) A recording apparatus for digital signals, characterized in that 9. A digital signal recording apparatus according to claim 6, wherein said recording signal is recorded on a recording medium such as an optical disk or a magnetic disk or a magnetic tape. 10. A recording frequency characteristic of a pit train of a recording signal is recorded with an equalization characteristic, and the recording signal is recorded so as to compensate the spatial equalization frequency characteristic of a reproducing side pickup. A recording medium for digital signals, which is a recording signal that does not require an equalizing circuit for reproducing signals on the reproducing side. 11. A digital signal characterized in that an equalization characteristic is added to a recording frequency characteristic of a pit train of a recording signal for recording, and the recording signal is a recording signal generated as follows. A signal recording medium. That is, a second signal obtained by giving a predetermined frequency characteristic G (fs) to the binary first signal is obtained, and the equalization characteristic EQ (fs) on the reproduction side is further given to this second signal. This third signal
A signal is obtained by performing saturation amplification on the signal to obtain a fourth digital signal sequence, and the fourth digital signal sequence is the recording signal. 12. A second signal obtained by adding a predetermined frequency characteristic G (fs) to a binary first signal is obtained, and the equalization characteristic EQ (fs) on the receiving side is further added to the second signal. ) Is added to obtain a third signal, and the third signal is subjected to saturation amplification to obtain a fourth signal.
And transmitting the fourth digital signal sequence, the method for transmitting a digital signal. 13. The bit interval is Pw, bit 0 and bit 1
Transition point intervals of n × Pw to m × Pw (where n and m are n
A first step of generating a first signal in which information of the bit transition point interval is maintained by giving an ideal predetermined frequency characteristic to an input bit string of <m), and On the other hand, a second step of giving an equalized frequency characteristic to the output signal of the high-frequency receiving unit on the receiving side to generate a second signal, and saturation amplification of the second signal to convert it into a bit string for transmission. And a third step of obtaining the signal of 1. 14. The bit interval is Pw, bit 0 and bit 1
Transition point intervals of n × Pw to m × Pw (where n and m are n
A first means for generating a first signal in which the information of the bit transition point interval is maintained by giving an ideal predetermined frequency characteristic to the input bit string of <m integer); On the other hand, second means for generating a second signal by giving equalization frequency characteristics to the output signal of the high-frequency receiving unit on the receiving side, and for saturation amplification of the second signal for conversion into a bit string for transmission. And a third means for obtaining the signal of 1.