JPH05327515A - Information conversion system and information recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve a converting efficiency by adding one bit control bit to an (m) bit impression information column, and preparing an information column in order to emphasize a pilot signal. CONSTITUTION:The 0 or 1 control signal is added to the impression information column by control bit adding circuits 1 and 2. The information column is inputted to interleaved NRZI(I-NRZI) modulators 3 and 4, and information columns 0 and 1 are prepared. They are inputted to short time frequency analyzers 5 and 6, and the energy of a pilot frequency is analyzed. The size of the energy of the pilot frequency of the information columns 0 and 1 is inputted to a comparator 7, a changeover switch 8 is controlled so that the information column whose energy is larger can be impressed on an output, and the information column is impressed to the output. That is, the energy of the arbitrary frequency components is compared from two kinds of patterns obtained by adding the 0 or 1 bit control bit to the (m) bit information column, and one information column is selected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information conversion system, and an information conversion system capable of adding a pilot signal synchronized with an applied information sequence without superimposing the pilot signal on the applied information sequence and recording the same. The present invention relates to an information recording / reproducing device for reproducing.

[0002]

2. Description of the Related Art As a conventional technique, there is 8-10 conversion, which is described in Japanese Patent Laid-Open No. 1-317280. A device for converting a continuous information word (applied information word) of an applied digital signal into a channel word of a selected channel code before recording digital information on an information track of a recording medium. Different CDS (Codewo
rd Digital Sum). FIG. 16 shows an example diagrammatically showing a table having three channel word columns (C1, C2, C3). One column is provided with 256 (= 2 ⁸ ) information words, which represent 0 to 255 in decimal notation. For each information word I (i) each column has one channel word Cj
(I), j = 1, 2, or 3 is included. Also, they have different CDSs. Therefore, 1
Three channel words are available for one information word I (i).

The 8-10 transform has a second signal with a relatively low frequency carrier for the recorded information signal. This is a pilot signal which serves as a tracking signal which gives information about the relative position of the read element with respect to the information track, ie the position transverse to the track direction. In order to insert the pilot signal into the data stream of the channel word, a control signal is generated in response to the second signal, the average value of the recorded digital signal being approximately equal to the change of the relatively low frequency second signal. Channel words are selected from the table of FIG. 16 so as to change.

[0004]

The conventional 8-10 conversion, which is an information conversion system, is configured as described above. 8-10
The conversion efficiency of the conversion is 80%, and it was a problem to increase the conversion efficiency when performing higher density recording.

[0005]

In the information conversion method according to the present invention, control bits of 0 and 1 are added to an applied information string of m bits to generate two information strings of m + 1 bits, and each information string of It is an information conversion method that analyzes the frequency, compares the magnitude of the energy of the analyzed frequency, and applies one information string to the output according to the comparison result, and becomes a pilot signal in the applied information string. It is characterized in that a signal added with a control bit so as to emphasize a certain frequency component is selected as an output.

[0006]

In the present invention, in order to emphasize the pilot signal, the 1-bit control bit is added to the m-bit applied information sequence to generate the information sequence, so that the conversion efficiency is enhanced.

[0007]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an example of a circuit configuration diagram of an information conversion device using an information conversion system according to the present invention, in which 1 is a control bit addition circuit for adding a control bit 0 to an applied information string, and 2 is a control bit 1 for an applied information string. Control bit adding circuit for adding 3,
4 is an interleaved NRZI (I-NRZI) modulator, 5 and 6 are added with a control bit 0, and I-NRZ
Short time for frequency-analyzing an I-modulated signal sequence (hereinafter referred to as information sequence 0) and a control bit 1 and performing I-NRZI-modulated signal sequence (hereinafter referred to as information sequence 1) A frequency analysis circuit, 7 is a comparator for comparing the analysis results from the short-time frequency analysis circuit, 8 is a changeover switch for applying the information sequence 0 or the information sequence 1 to the output based on the comparison result from the comparator 7, Reference numeral 9 is a memory for storing output data. FIG. 18 shows an information recording / reproducing apparatus according to this embodiment, 21 is the information converting apparatus of FIG. 1 and 22 is a REC Am.
p and 23 are magnetic tapes, 24 is PB Amp, 25 and 26 are BPFs for extracting pilot signals, 27 and 28 are integrators that integrate the extracted pilot signals into DC values, 29 is a differential amplifier, 30 Is a tracking control circuit, 31 is a tracking motor, 32 is an A head, and 33 is a B head. FIG. 17 is an example of a track pattern and tracking state diagram recorded by the information recording / reproducing apparatus according to the present invention. 17 is an A track having plus azimuth on which a signal to which a pilot signal is added is recorded, and 18 is a pilot B track with a negative azimuth on which a signal with reduced frequency energy of the signal is recorded, 19 is a B track for reproducing the B track 18.
The head.

Next, the operation will be described. The applied information string is digital data of 0 or 1. Now, when this applied information string is made up of 1 word of 14 bits, one control bit is added to this, which is called 14-15 conversion. The conversion efficiency at this time is 93.3%, which is 80% of 8-10 conversion.
It can be seen that the conversion efficiency is higher than that of%. The 14-15 conversion will be described below.

A control signal of 0 or 1 is added to the applied information string by the control bit adding circuits 1 and 2, respectively. This is input to the I-NRZI modulators 3 and 4, and the information sequence 0 and the information sequence 1 are generated. These are input to the short-time frequency analyzers 5 and 6 to analyze the energy of the pilot frequency. The definition formula of the short-time frequency analysis is shown below.

[0010]

[Equation 1]

X is the applied information sequence, and h is the impulse response of the FIR filter. The analysis frequency is the phase term e
^-determined by ^jwrT . This can be expanded from Euler's formula as e- ^jwrT = cos (ωrT) -j sin (ωrT). The pilot frequency is constant, and cos (ωrT) and s
in (ωrT) is included in the value of the multiplier of each tap. In addition, the magnitude of energy is a value obtained by multiplying each of them by the square and multiplying them by the route. In the circuit of this embodiment, only the magnitude of energy is compared, so the route circuit is omitted.

The magnitude of the pilot frequency energy of each of the information sequence 0 and the information sequence 1 is input to the comparator 7, and the changeover switch 8 is controlled so that the information sequence having the larger energy is applied to the output, An information string is applied to. This output is also applied to the memory 9, which is fed back to the short-time frequency analysis circuit and added to each of the information sequence 0 and the information sequence 1 to be applied next, and the frequency analysis is performed with a bit of a predetermined length.

As an example, the sampling frequency of the applied information sequence is fs = 25 MHz and the pilot frequency is fp = 208.3 KHz.
The 14-15 modulation with (fs ÷ 120) is described below. In short-time frequency analysis, the frequency resolution of analysis data is determined by the characteristics of the FIR filter. The FIR filter is a low pass filter (LPF), and the lower the cutoff frequency, the better the frequency resolution. This state is shown in FIGS. 2, 3, 4, and 5. 2 is a frequency analysis of the frequency spectrum of the applied information sequence, and FIG. 3 is
FIR filter with 120 taps (cutoff frequency fc
= 208.3 KHz), the simulation result of the short-time frequency analysis circuit is the same as Fig. 4 with 240 taps (fc = 104.
2 KHz), and 480 taps (fc = 52.1 KHz) in Fig. 5 as well.
belongs to. It can be seen that the cutoff frequency can be lowered and the frequency resolution can be increased as the number of filter taps increases.

However, since the circuit scale increases as the number of taps increases, a compromise is required. At 120 taps, the spectrum of the pilot frequency is buried in other spectra due to the low frequency resolution, and cannot be used as a criterion. The 240 taps and 480 taps have a spectrum and can be used. However, 240 taps with low frequency resolution may cause misjudgment, and the spectrum near the pilot frequency of the digital data string after information conversion becomes slightly larger. The pilot signal is extracted by a bandpass filter (BPF) when tracking is performed, but it is considered to be negligible depending on the frequency characteristics of this BPF, and it is configured with 240 taps below.

FIG. 6 shows a simulation result of the information conversion device according to the present embodiment constructed by using a filter of 240 taps. The pilot frequency is about 12 dB. Further, FIG. 7 shows a simulation result when the information sequence is selected in the comparator 7 so as to reduce the energy of the pilot frequency. In this way, it is possible to reduce the energy of the pilot frequency.
It can be used as follows. FIG. 18 shows an information recording / reproducing apparatus according to this embodiment. A pilot signal is added to the applied information sequence by the information conversion device 21, and REC Amp is added.
It is amplified by 22 and recorded on the magnetic tape 23 by the A head 32 and the B head 33 having different azimuth angles. FIG. 17 shows a tracking state of the information recording / reproducing apparatus according to the present invention. It is assumed that pilot signals of different frequencies are recorded on the A tracks 17 and 20, and the tracking is adjusted to the B track 18. The signal reproduced from the B head 19 is the signal recorded on the B track 18 and the adjacent A track.
This is the pilot signal reproduced by crosstalk from 17 and 20. This is amplified by PB Amp24, and each pilot signal reproduced by crosstalk is BP.
After being extracted by F25 and 26 and converted into a DC value by integrators 27 and 28, the respective magnitudes of the pilot signals, that is, the magnitudes of crosstalk, are compared by the differential amplifier 29. This output is input to the tracking control circuit 30 and the tracking motor 31 is controlled to match the tracking.
At this time, if the energy of the pilot frequency component of the signal recorded on the B track 18 is small, the energy of the pilot signal that is the tracking signal is equal to the energy of the pilot signal of the A track 17 and the decrease of the pilot frequency of the B track 18. And the S / N is improved.

The short-time frequency analysis can correct the frequency if it is equal to or higher than the FIR filter cutoff frequency, and the pilot frequency can be freely selected within that range. This is shown in FIGS. 8 and 9. Figure 240
The pilot frequency is fp = 314 K with the tap filter
As a result of simulation when Hz (fs ÷ 80) is used, FIG. 9 shows that the pilot frequency is fp with a filter of 240 taps.
= 250 KHz (fs / 100) is a simulation result. Since the number of taps of the filter is 240, in the case of FIG. 8 (fp = fs 80), the filter under analysis always includes pilot frequencies for 3 cycles. In the case of FIG. 9 (fp = fs ÷ 100), 2.
The pilot frequency for 4 cycles is included. Comparing these, it can be seen that the energy of the pilot frequency is larger by 2 to 3 dB in FIG. That is, it can be understood that the pilot signal after information conversion becomes large if the number of taps of the FIR filter is determined so that an integer number of periods of the pilot frequency are included in the filter. This is shown in Figure 6 (fp =
The same applies to fs ÷ 120, 2 cycles), and the number of taps of the filter may be determined so that the pilot signal becomes large in this way.

Although the 14-15 modulation has been described above, the present invention is not limited to this, and modulation with one redundant bit can be performed by a simple circuit modification. As an example, Fig. 10 shows 19-20 modulation (conversion efficiency 95%), Fig. 11
Shows the simulation results when 24-25 modulation (conversion efficiency 96%) is performed. In principle, the higher the conversion efficiency, the smaller the energy of the pilot signal after information conversion, but the pilot signal can be obtained, and the pilot signal can be selected according to the conditions of the device used.

Example 2. FIG. 12 shows the circuit configuration of the second embodiment according to the present invention. The same circuits as those in the first embodiment are denoted by the same reference numerals as those in FIG. 1 and their description is omitted. Reference numerals 10 and 11 are changeover switches, 12 is a switch changeover control circuit for controlling the changeover switch, and 13 is a memory. Selector switch
10 and 11 are interlocked with each other by a switch switching control signal, for example, first analyze the pilot frequency component of the information string 0,
The result is stored in the memory 13. Next, the changeover switches 10 and 11 are switched to analyze the pilot frequency component of the information sequence 1 and input to the comparator 7 to be compared with the analysis result of the information sequence 0. In this way, one short-time frequency analysis circuit can be configured, so that the circuit scale can be reduced.

Example 3. FIG. 13 shows a short-time frequency analysis circuit of the information conversion apparatus according to this example. Reference numeral 14 is a multi-stage switch, 15 is a switch group, and 16 is a pilot frequency selection circuit. The phase term COS (ω) when performing frequency analysis in the short-time frequency analysis circuit of FIG.
The frequencies analyzed by changing ω of rt) and SIN (ωrt) are different. Here, if n ωs are prepared and selected by the multi-stage switch 14, it is possible to add a pilot signal component in which an arbitrary pilot frequency is selected in the same circuit configuration to the applied information sequence.

Example 4. Although the I-NRZI modulators 3 and 4 are used as the precoder in the first embodiment, an NRZI modulator as shown in FIG. 14 may be used. FIG. 15 shows the result of information conversion simulation in this case. In the case of NRZI modulation, since the polarities of the CDS of the information sequence 0 and the information sequence 1 are opposite to each other, it is clear that the energy of the pilot signal can be increased as compared with FIG.

Further, in the first embodiment, the energy of an arbitrary frequency component is compared from two types of patterns in which a 1-bit control bit of 0 or 1 is added to an m-bit information string, and one information is compared. Although a column was selected, the control bit is n bits, and 2 ⁿ kinds of patterns (for example, n =
In case of 2, 00 + m, 01 + m, 10 + m, 11 + m (2+
It is clear from the above description that a pilot signal with a larger energy (attenuated) can be obtained by selecting an information sequence that has the largest (smallest) arbitrary frequency component from (m) four types of patterns). Is. However,
In this case, the coding rate is from m / (m + 1) to m / (m +
We must be prepared to decline to n).

[0022]

As described above, the information conversion method according to the present invention is configured to add a 1-bit control signal to the applied information sequence to perform information conversion and add the pilot signal to the bit stream of the output signal. The conversion efficiency can be improved.

Further, since the frequency of the pilot signal after information conversion is determined only by the cos (ωrT) and sin (ωrT) which are the phase terms of the short-time frequency analysis, the pilot frequency can be easily changed.

Further, the frequency of the pilot signal after information conversion is determined only by cos (ωrT) and sin (ωrT) which are the phase terms of the short-time frequency analysis. Therefore, if these are arbitrarily switched, the same circuit can be used. The pilot signal can be arbitrarily selected and added to the applied information sequence.

[Brief description of drawings]

FIG. 1 is an embodiment of a circuit configuration of an information conversion device according to the present invention.

FIG. 2 is frequency analysis data of an example of an applied information sequence applied to a short-time frequency analysis circuit.

3 is a result of short-time frequency analysis of the applied information string of FIG. 2 with a filter of 120 taps.

FIG. 4 is a result of short-time frequency analysis of the applied information sequence of FIG. 2 with a filter of 240 taps.

5 is a result of short-time frequency analysis of the applied information string of FIG. 2 with a filter of 480 taps.

6 is a result of frequency analysis of the output 14-14 converted by the filter of 240 taps by the information conversion apparatus of FIG. 1, with a pilot frequency of (fs ÷ 120).

7 is a frequency analysis result of the information converted by the information conversion device of FIG. 1 so that the pilot signal becomes smaller by the filter of 240 taps.

8 is a frequency analysis result of the information converted by the filter of 240 taps by the information conversion device of FIG. 1, in which the pilot frequency is (fs ÷ 80).

9 is a frequency analysis result of the information converted by the filter of 240 taps by the information conversion device of FIG. 1, in which the pilot frequency is (fs ÷ 100).

FIG. 10 is a result of frequency analysis of output 19-20 converted by the information conversion device according to the present invention.

FIG. 11 is a frequency analysis result of an output converted by 24-25 by the information conversion device according to the present invention.

FIG. 12 shows an example of a circuit configuration of an information conversion device according to the present invention.

FIG. 13 is an example of a short-time frequency analysis circuit used in the information conversion device according to the present invention.

FIG. 14 is an NRZI modulator.

15 is an information conversion device when the I-NRZI modulators 3 and 4 are NRZI modulators in the circuit configuration diagram of FIG.
Frequency analysis result of 14-15 converted by 0 tap filter, pilot frequency is (fs ÷ 120).

FIG. 16 is an example of a diagram showing a conversion table for 8-10 conversion.

FIG. 17 shows an example of track patterns and tracking recorded by the information recording / reproducing apparatus according to the present invention.

FIG. 18 is an example of a configuration diagram of an information recording / reproducing apparatus according to the present invention.

[Explanation of symbols]

 1, 2 Control bit addition circuit 3, 4 I-NRZI modulator 5, 6 Short-time frequency analysis circuit 7 Comparator 8, 10, 11 Changeover switch 9, 13 Memory 12 Switch changeover control circuit 14, 15 Multi-step changeover switch 16 Pilot frequency selection circuit 17, 20 A track 18 B track 19 B head 15 Changeover switch group 21 Information converter 22 REC Amp 23 Magnetic tape 24 PB Amp 25, 26 BPF 27, 28 Integrator 29 Differential Amp 30 Tracking control circuit 31 Tracking motor

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 14, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

EXAMPLES Example 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an example of a circuit configuration diagram of an information conversion device using an information conversion system according to the present invention, in which 1 is a control bit addition circuit for adding a control bit 0 to an applied information string, and 2 is a control bit 1 for an applied information string. Control bit adding circuit for adding 3,
4 is an interleaved NRZI (I-NRZI) modulator, 5 and 6 are added with a control bit 0, and I-NRZ
Short time for frequency-analyzing an I-modulated signal sequence (hereinafter referred to as information sequence 0) and a control bit 1 and performing I-NRZI-modulated signal sequence (hereinafter referred to as information sequence 1) A frequency analysis circuit, 7 is a comparator for comparing the analysis results from the short-time frequency analysis circuit, 8 is a changeover switch for applying the information sequence 0 or the information sequence 1 to the output based on the comparison result from the comparator 7, Reference numeral 9 is a memory for storing output data. FIG. 18 shows an information recording / reproducing apparatus according to this embodiment, 21 is the information converting apparatus of FIG. 1 and 22 is a REC Am.
p and 23 are magnetic tapes, 24 is PB Amp, 25 and 26 are BPFs for extracting pilot signals, 27 and 28 are integrators that integrate the extracted pilot signals into DC values, 29 is a differential amplifier, 30 Is a tracking control circuit, 31 is a tracking motor, 32 is an A head, and 33 is a B head. FIG. 17 is an example of a track pattern and tracking state diagram recorded by the information recording / reproducing apparatus according to the present invention. Reference numerals 17 and 20 denote positive azimuths on which a signal to which a pilot signal is added is recorded. The track A has 18, a track B having a minus azimuth in which a signal in which the frequency energy of the pilot signal is reduced is recorded, and a B head 19 for reproducing the track B 18.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

In the short-time frequency analysis, it is possible to perform frequency analysis as long as it is equal to or higher than the FIR filter cutoff frequency, and the pilot frequency can be freely selected within that range. This is shown in FIGS. 8 and 9. Figure 240
The pilot frequency is fp = 314 K with the tap filter
As a result of simulation when Hz (fs ÷ 80) is used, FIG. 9 shows that the pilot frequency is fp with a filter of 240 taps.
= 250 KHz (fs / 100) is a simulation result. Since the number of taps of the filter is 240 taps, in the case of FIG. 8 (fp = fs-80), the filter under analysis always includes pilot frequencies for three cycles. In the case of FIG. 9 (fp = fs ÷ 100), 2.
The pilot frequency for 4 cycles is included. Comparing these, it can be seen that the energy of the pilot frequency is 2-3 dB higher in FIG. That is, it can be understood that the pilot signal after information conversion becomes large if the number of taps of the FIR filter is determined so that an integer number of periods of the pilot frequency are included in the filter. This is shown in Figure 6 (fp =
The same applies to fs ÷ 120, 2 cycles), and the number of taps of the filter may be determined so that the pilot signal becomes large in this way.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Front Page Continuation (72) Inventor Takehi Hibi Nagaokakyo Baba Zoujo 1 No. 1 Electronic Product Development Laboratory, Mitsubishi Electric Corporation (72) Inventor Masako Nagaoka Kyoichi Baba Zoujo 1 Mitsubishi Electric Co., Ltd. Electronic Products In development lab

Claims (4)

[Claims] 1. In an information conversion system in which a pilot signal of an arbitrary frequency is added to an applied information sequence, a control bit of 0 and 1 is added to an applied information sequence of m bits to obtain m +.
Two 1-bit information strings are generated, a frequency component is analyzed from the information string of a predetermined length including at least each of the information strings, and the magnitude of energy of an arbitrary frequency component of the information string of the respective predetermined length is analyzed. And an information conversion method of applying one of the information strings to the output according to the comparison result. 2. The method of short-time frequency analysis is used as the frequency analysis means, and the number of taps of the FIR filter is determined so that an integer number of periods of the arbitrarily determined frequency are included. Information conversion method described. 3. A plurality of types of frequencies are included in the applied information sequence by having a plurality of short-term frequency analysis phase terms for adding arbitrary frequencies to the applied information sequence and arbitrarily switching the plurality of phase terms. The information conversion method according to claim 1, wherein 4. An information recording / reproducing apparatus for reproducing a signal recorded on a plurality of tracks having two different azimuths by tracking the respective tracks, and recording a signal to which a pilot signal is added to one of the azimuth tracks. An information recording / reproducing apparatus having means and, on the other hand, means for recording a signal in which a frequency component of a pilot signal is reduced.