JPS6280864A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To realize a high definition audio signal or the like by a device operated at a low frequency by providing two systems of decoders operated respectively by clocks having the same frequency but different phases by 180 deg.. CONSTITUTION:Two systems of D/A converters 52 operated by the same 48KHz clock are provided, the outputs of two systems of converters 52A, 52B are fed to a sample and hold circuit 54, and the output is inputted to an LPF53. The 48KHz clock is inputted to the converter 52A, the clock is delayed by 180 deg. by a delay circuit 55 and inputted to the converter 52B, and the said clock and a clock retarded by 180 deg. are fed to the sample and hold circuit 54. The circuit 54 applies the sample and hold to the output of the converter 52A by using the clock and to the output of the converter 52B corresponding to the retarded clock respectively, and the synthesized output is smoothed by the LPF53 and the original signal is reproduced. Thus, a 96KHz sampling signal is recorded/reproduced without the provision of a 96KHz clock decoder.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information recording and reproducing apparatus that converts an analog signal into a digital signal and records and reproduces the converted signal on a recording medium.

[Summary of the invention]

The present invention provides an information recording and reproducing apparatus that converts an analog signal into a digital signal and records and reproduces it on a recording medium, in which two encoders or decoders operating with a clock of the same frequency are used.
A system is provided so that the phase of the clock that drives one encoder or decoder and the phase of the clock that drives the other encoder or decoder are shifted by 180 degrees from each other,
This makes it possible to enjoy higher quality audio signals in devices that operate with a lower frequency clock.

[Conventional technology]

Recently, so-called 8m video tape recorders have been standardized and commercialized. In this 8 m video tape recorder, the rotating diameter of the magnetic head per rotation (the diameter of the rotating drum) is 40 m, and the winding angle of the magnetic tape around the rotating drum is 22 m.
It is said to have happened once.

A video signal is recorded in the portion corresponding to a winding angle of 180 degrees, and a PCM audio signal is recorded in a portion corresponding to a winding angle of 36 degrees.
The remaining 5th part is considered the remainder). If we divide this 36 degree portion into more detail, there is a portion a where a clock signal is recorded and a portion where data such as a PCM audio signal is recorded.

side Margin section C for after-recording.

The video overlap area d is divided into a video overlap area d in which the video signal of the immediately previous field is continuously recorded. Then, tracking pilot signals f, f, f3, f4 are sequentially recorded for each track over the entire portion corresponding to the winding angle of 221 degrees. These pilot signals f□, f
2. f,, f4 is.

For example, f1158, fN150, f, /36, f
++/40 (fw is a horizontal synchronization signal). A tracking error signal is generated from crosstalk components from the left and right tracks of the pilot signal continuously recorded on each track. The rotational speed of the rotating magnetic head is 1800 ppm for the NTSC system and 1500 ppm for the PAL system because it records video signals.
rpm. Also, in the part corresponding to the winding angle of 180 degrees, there are multiple parts (5
It is now also possible to create an audio signal (individual) and record only the audio signal.

The audio signal recorded in the 36 degree area has a sampling frequency of 2fH (approximately 31.5:7) and a quantization bit count of 10 bits (however, on the magnetic tape, 10 bit data is converted to 8 bits). (compressed) and recorded)
, the number of channels is 2.

On the other hand, R-DAT has recently been standardized in order to record and reproduce audio signals on magnetic tape with even higher quality.

In R-DAT, the winding angle of the magnetic tape is 90 degrees, the diameter of the rotating drum is 30 degrees, and the sampling frequency is 4 degrees.
8k) lz, 44. The frequency is either 1K or 32kHz, the number of quantization bits is 16 bits, and the number of channels is 2.

The track corresponding to the winding angle of 90 degrees is divided into 16 parts as shown in FIG. 4, and data is recorded in each part as shown in Table 1. Here, one block consists of 288-bit data, and 8-bit data is converted (modulated) to 10-bit data and recorded on the magnetic tape.

Furthermore, in the same table, fch has a frequency of 9.408MHz, the first
This is the black signal on the table.

As can be seen from Table 1, this data mainly consists of parts 2.3.
4, a tracking signal recording section consisting of section 5.6.7, a PCM audio signal recording section consisting of section 8.9, and section 10.11.12.
a tracking signal recording section consisting of parts 13, 14.
15 subcode signal recording sections.

[Problem that the invention seeks to solve]

There are two methods for recording and reproducing digital audio signals on a magnetic tape using a rotating magnetic head, and the sound quality is determined by the sampling frequency. Therefore, low sampling frequency devices have not been able to achieve the sound quality of high sampling frequency devices.

[Means for solving problems]

FIG. 1 shows a block diagram of an information recording and reproducing apparatus (8III video tape recorder) of the present invention.

In the figure, 1 is a rotating drum (
(not shown), the rotary magnetic head 1 is alternately supplied with signals from the recording amplifier 4 via a switch 2.3, and the signal from the rotary magnetic head 1 is The signal is output to a regenerative amplifier 5 via switches 2 and 3. The recording amplifier 4 is supplied with signals from a video modulator 8 and a PCM encoder 9 via a switch 6, and is also supplied with a pilot signal output from a pilot signal generator 35. Further, the signal from the regenerative amplifier 5 is outputted to the video demodulator 1o and the PCM decoder 11 via the switch 7. 12 and 13 are a PCM decoder and a PCM encoder compatible with the R-DAT format; the signal from the regenerative amplifier 5 is supplied to the PCM decoder 12 via switch 7, and the output of PCM encoder 13 is supplied to switch 6. The signal is supplied to the recording amplifier 4 via. 14 generates a clock signal f'ch and PCM
This is an oscillator outputting to the encoder 13.

Reference numeral 15 denotes a motor that rotates the rotating drum, and includes a frequency generator 16 and a pulse generator 17, and a drive circuit 18.
is driven by. The output of the frequency generator 16 is input to a frequency control circuit 19, which compares it with a predetermined reference signal output from a built-in oscillation circuit.The frequency control circuit 19 outputs an error signal. 20 is a phase control circuit;
A vertical synchronization signal included in the recorded video signal separated by the synchronization separation circuit 22, a reference signal outputted by the oscillator 23, a reference signal outputted by the PCM decoder 12, or P
Either of the reference signals output by the CM encoder 13 is
0 input as a reference signal via switch 21
The phase control circuit 2o compares the phases of the pulses output by the pulse generator 17 and the reference signal, and outputs a signal corresponding to the error.The output of the zero frequency control circuit 19 and the output of the phase control circuit 20 are added to the adder circuit. 24 and is supplied to the drive circuit 18.

25 is a motor that rotates a capstan (not shown), and is equipped with a frequency generator 26.

The output of the frequency generator 26 is supplied to a frequency control circuit 27 and a frequency dividing circuit 28. The frequency control circuit 27 uses a predetermined reference signal output from a built-in oscillation circuit and the frequency generator 2.
The zero frequency divider circuit 28 compares the output of the frequency generator 26 with the output of the frequency generator 26 and outputs the error signal to the adder circuit 3o. The phase control circuit 29 compares the signal from the switch 21 and the signal from the frequency divider circuit 28 and outputs the error signal to the adder circuit 30 via the switch 34. The adder circuit 30 adds the output of the frequency control circuit 27 and the output of the phase control circuit 29, and outputs the result to the drive circuit 31.

The drive circuit 31 is configured to drive the motor 25. 32 is a tracking control circuit that separates and extracts a pilot signal from the output of the regenerative amplifier 5, generates a tracking error signal, and sends the signal to the adder circuit 30 via a switch 34.
It is output to. 33 is a central processing unit (CPU) such as a microcomputer, which controls each circuit, means, switch, etc. in conjunction with a main central processing unit (not shown).

[Effect]

The effect will now be explained. When a command to record a normal video signal and an accompanying PCM audio signal is input, the CPU 33 controls the frequency control circuit 19.27,
A control signal is sent to the drive circuit 18.
ppm (1500 ppm in the case of the PAL system), and the capstan is rotated by the motor 25 so that the speed of the magnetic tape (not shown) becomes the standard speed.

At this time, the frequency control circuit 19 applies servo so that the frequency of the signal output by the frequency generator 16 becomes equal to the frequency of the built-in reference signal. At this time, the switch 21 is switched to select the output of the sync separation circuit 22, and the 1-phase control circuit 20 rotates the rotary drum in synchronization with the phase of the vertical sync signal in the video signal to be recorded. A head switching pulse (H8WP), which is a reference for switching the rotating magnetic head, is generated and output to each circuit.

Similarly, the frequency control circuit 27 and the phase control circuit '2
9 applies frequency servo and phase servo to the motor 25. At this time, the phase control circuit 29 uses the output of the synchronous separation circuit 22 outputted by the switch 21 as a reference, and the 1 frequency division circuit 2
An error signal with respect to the output of 8 is supplied to an adder circuit 30 via a switch 34. Therefore, the specified speed (14.345 m/s for NTSC system, 20.051 m/s for PAL system)
The speed of the magnetic tape is controlled so that the speed of the magnetic tape is aa/s).

The video signal to be recorded is input to a video modulator 8 and subjected to one frequency modulation. Also, the recorded audio signal is
These signals, which are input to the M encoder 9 and digitized (PCM), are sent to the recording amplifier 4 via the switch 6.
, further supplied to the rotary magnetic head 1 via the switch 2.3, and recorded on the magnetic tape. Phase control circuit 20
1 based on the head switching pulse output by
A video signal is recorded in the 80-degree video signal recording section, and an audio signal is recorded in the 36-degree audio signal recording section. Also, at this time, a tracking pilot signal generated by the pilot signal generator 35 is frequency-multiplexed with the video signal and the PCM audio signal and recorded. The frequency can be the same as the pilot signal in the case of the PAL system. In this way, the clock signal f'c
It becomes easy to frequency divide and generate a pilot signal from h.

When reproducing a video signal, the output signal of the oscillator 23 (signal corresponding to the vertical synchronization signal) is supplied to the phase control circuit 20 as a reference signal via the switch 21. Further, the switch 34 is switched to the tracking control circuit 32 side, and the phase servo of the motor 25 is performed in response to the tracking error signal generated from the crosstalk components of the pilot signals recorded on the left and right adjacent tracks.

The reproduction signal from the rotating magnetic head 1 is transmitted to the video demodulator 10 and P via the switch 2.3, the reproduction amplifier 5, and the switch 7.
It is input to the CM decoder 11. Therefore, the video signal recorded in the 180-degree video signal recording section and the audio signal recorded in the 36-degree audio signal recording section are each demodulated and output.

Next, when recording only high-quality audio signals, the audio signals are input to the PCM encoder 13 and digitized. PCM encoder 13 is located at 11R-DA
The same PCM encoder as in T can be used. However, the PCM encoder 13 is controlled at a different timing by a different clock than in the R-DAT.

In other words, in the present invention, one track with a length corresponding to a winding angle of 221 degrees has a length of 54 degrees as shown in FIG.
It is divided into four areas with a length of 2.0 degrees.
A surplus of 44 degrees and 2.956 degrees is provided. The 54-degree length area A is further divided into nine parts as shown in FIG. 3, and data is recorded in each part as shown in Table 2.

As is clear from Table 2, in the present invention, the tracking data recording sections 5.6.7 and 1o in Table 1 are
, 11.12, and the last margin part 16 are removed, and the clock f'ch here is, for example, 12.
．． 864M seven (=160.8x288x (10/8)
10.0045). Of course, the combination can be changed within the range where the winding angle of 54 degrees and the recording time of 4500 μS are maintained. For example, a 2-block PLL (
PCM) Clock recording section is blank, margin section is 8.8
It is also possible to change from 10.8 block to 10.8 block. Furthermore, the remaining portions at both ends can be arbitrarily selected.

In this way, R-DA, which has already been standardized,
Information can be recorded and reproduced simply by changing the timing without changing the coding of the T format.

The audio signal input to the PCM encoder 13 is
The signal is digitized in response to the clock signal f'ch inputted from the oscillator 14, and its timing is controlled by the CPU 33 to convert it into a signal in the format shown in Table 2. This signal is sent to the switch 6, the recording amplifier 4.
The signal is supplied to the rotating magnetic head 1 via switches 2 and 3, and recorded on the magnetic tape. At this time, the phase control circuit 2
Based on the head switching pulse output by 0.

An area pulse corresponding to at least one of the areas A to A is generated, and a signal is recorded in the area corresponding to the area pulse.

At this time, the frequency control circuit 19 and the drive circuit 18 are controlled by the CPU 33 to rotate the rotary drum at 2000 rpm. Further, the switch 21 supplies a signal synchronized with the clock f'ch output from the PCM encoder 13 to the phase control circuit 20 as a reference signal. Furthermore, the frequency control circuit 27 and the drive circuit 31 are controlled in the same manner, and the speed of the magnetic tape is set to the standard speed of the PAL system, 20.051/S.
The speed is set to 10.025 mm/s, which is 1/2 of that.

When set to this speed, the track pitch becomes 13.3 μm, and the rotating magnetic head for the standard speed of the NTSC system or the rotating magnetic head for 1/2 speed of the standard speed of the NTSC system, and the rotating magnetic head for the 1/2 speed of the standard speed of the PAL system. The width of the head falls within a range that allows recording and reproduction of audio signals and pilot signals, as well as tracking control based on the crosstalk component of the pilot signal, eliminating the need to use a rotating magnetic head with a special width.

When reproducing the audio signal recorded in this manner, the signal from the rotating magnetic head 1 is input to the reproducing amplifier 5 via the switch 2.3, and further supplied to the PCM decoder 12 via the switch 7. PCM decoder 1
2 is controlled by the CPU 33 and generates the clock f' from the reproduction signal.
Extract the channel and read the data of each part using it as a reference. The audio signal is converted into an analog signal and output. Further, a pilot signal for tracking included in the reproduced signal is input to the tracking control circuit 32,
A tracking error signal is generated.

This tracking error signal is output to the adder circuit 30 via the switch 34, and tracking control is performed.

In other words, in R-DAT, as is clear from Table 1, a tracking signal (ATF) is recorded before and after the PCM audio signal recording section, and the crosstalk components from that part of the left and right tracks are However, in the present invention, as in the case of a normal eight-track video tape recorder, the tracking error signal is sampled and held at the timing of A tracking error signal is generated from the difference signal of crosstalk components from the left and right tracks of the pilot signal.

Next, the data to be recorded in each area A through can be configured as shown in Table 3, for example. That is, when the recorded information is a stereo audio signal (R), and the sampling frequency is 48k) Iz, a predetermined number of data sampled by each clock in Table 3 (
If consecutive numbers are assigned to the words), then the odd numbered L
The signal (Lo) and even numbered R signal (Re) are recorded in area A, and the odd numbered R signal (RO) and even numbered L signal (Le) are recorded in area A of the next adjacent track. . That is, the data is interleaved into two tracks (
further interleaved within each track)
, it is now possible to reproduce complete data by obtaining signals from two tracks. Of course R-D
If the advantage of using the same encoder and decoder as AT is abandoned and a different encoder and decoder is used, such interleaving can be set arbitrarily. Similar records are in each area B and C.

In this case, information of two channels (L, R) can be recorded four times on one inclined track. Note that in Table 3, only data LO and Re are listed for convenience (the same applies hereinafter).

Set the sampling frequency to 9, which is twice the reference frequency of 48kHz.
When & is set to 6, first the even numbered signal Le.

Re, and odd numbered signals Lo and Ro.

Then, a new order is assigned to the even-numbered signals Le and Re, and the same classification as described above is performed for the new order. In other words, the signal L whose new order is an odd number
o2 and the even-numbered signal Re2 are recorded in the area A, and the new odd-numbered signal Ro2 and the even-numbered signal Le are recorded in the next adjacent area A. And the signal L whose original order is an odd number
A new order is added to signals o and Ro, and the same processing is performed, but these signals are recorded in area B. As a result, the signal recorded in each area is substantially 48 kl (z
The signal is the same as that sampled at 48 kHz, and when decoded with a 48 kHz clock decoder, the same audio signal as sampled at 48 kHz can be reproduced. This becomes impossible if, for example, one sampled data is divided into upper bits and lower bits and each bit is recorded in a different area.

Furthermore, the sampling frequency is set to 192, which is four times the reference frequency.
For example, as shown in FIG. 5, sampling values L11 . R,1, the sampled value L2□, R21 after 4 clocks, and the sampled value 4 clocks later,..., R,1, etc.
one group. Similarly, the sampling value L1
．． ．． R-work 2. L2□, R32, L3□, R12, etc. are made into one group, and the sampling value L1. .

R11, L23. R23, L33. Let R33 etc. be one group, and take the sampling value L L 4 T R1...,,R
, Iri, 4. The R mouth etc. will be considered as one group. Then, the same processing as described above is performed so that each of these four groups is recorded in a different area A to each other. For example, if a new order is assigned in the first group, the odd numbered signal Lo4. and even-numbered signals Re are recorded in area A, and odd-numbered signals Ro4° and even-numbered signals Le4 are recorded in the next adjacent area A, respectively.

As a result, in this case as well, as in the case described above, the signal recorded in each area becomes substantially equivalent to a signal sampled with a clock of the reference frequency, and reproduction using a decoder of the reference frequency becomes possible.

Similarly, if data is divided into data groups of every two samples, reproduction using a decoder with a frequency twice the reference frequency becomes possible.

Therefore, in any case, it is clear that it is preferable to make the recording area compatible with a lower sampling frequency.

Next, a case will be described in which, for example, front and rear audio signals (F, B) are added to the stereo audio signal (L, R) to record a four-channel audio signal. In this case, when the sampling frequency is set to the reference frequency of 48 kHz, left and right stereo signals (L, R) are sequentially recorded in area A, and corresponding front and rear signals (F, B) are recorded in each area. In principle, left and right audio signals (L
.

It is also possible to record audio signals (F, B) before and after (R) in one area. However, if you do that, you will have two channels of stereo signals (left and right signals (L, R).
)”)L, or cannot be played on devices that cannot play it.Therefore, the left and right signals (L, R) and the front and rear signals (
F and B) are preferably recorded in different areas. Left and right signals (L.

R) and front/rear signals (F, B) can be recorded in any area; the former can be recorded in areas B and A, and the latter can be recorded in areas C and D.
You can also record it in

In this case, since the left and right signals (L, R) and the front and back signals (F, B) can be recorded in areas C and D, respectively, information is recorded twice on one inclined track. In the above, the odd numbered signal Lo (Fo) and even numbered signal Re (Be) are recorded first in each area, and the odd numbered signal R is recorded in the next adjacent area.
o (Bo) and an even numbered signal Le (Fe). In this case, it can be arbitrarily determined in which area the left and right signals R and front and rear signals F and B are recorded, but the area where the left and right signals R and R are recorded is a 2-channel stereo Signal R, area where R is first recorded, or 9
It is preferable that the two-channel stereo signal with a sampling frequency of 6 kHz is made to correspond to the area in which R is recorded first or next.

96 times the standard frequency of the 4-channel audio signal
When sampling at kl (z, the sampling values for odd numbers, , Ro, F, , B, are first divided into the sampling values for even numbers, Le, Re, Fe, Be. Then, the signal for odd numbers is divided into L0.RO+F', t Bo and a new order is given to each of the even-numbered signals Le, Re, Fe, and Be.Odd-numbered signal L0
．． Out of R0, the signal Lo whose new order is an odd number, and the signal Re whose new order is an even number are placed in the area A, and the signal R04 whose new order is an odd number out of Ro is in the area A. The even-numbered signal Le4 is recorded in the next adjacent area A. Similarly, among the odd-numbered signals F, , , B, the signal Fo4 whose new order is an odd number and the signal Be4 whose new order is an even number are placed in the area, and the odd-numbered signals F0 . B.

Of these, the signal Bo4 whose new order is an odd number and the signal Fe4 whose new order is an even number are recorded in the next adjacent area B. Even-numbered signals Le, Re, Fe, and Be are recorded in areas C and D in the same way. In this case as well, the areas for recording left and right signals, R, and front and rear signals F and B can be set arbitrarily, but in the case of standard frequency 2-channel stereo recording and standard frequency 4-channel recording It is preferable to make it correspond to That is, for example, the left and right signals of the 96kHz sampling value, R, and the front and rear signals F and B of the 48kHz sampling value are recorded in the same area as the area where the left and right signals of the sampling value of 48kl (z and R are recorded. Signal F before and after sampling value of 96kHz in the same area as the area.

Record each item B. By doing this, 48
Even in a device having only a kHz sampling clock, it becomes possible to reproduce a signal with a sampling value of 96 kHz. In this case, information is recorded once on one inclined track.

It is clear that if the recorded information is made into mutually independent information S to Z, eight channels of information can be recorded with 48 kHz sampling.

If it is necessary to further lengthen the recording wavelength, areas A and B may be used as one area, and areas C and D may be used as one area.

The above description has been made assuming that the regions A to A are equivalent.

However, in reality, when recording and reproducing information using two rotating magnetic heads spaced 180 degrees apart, areas A or D
In this case, when one rotating magnetic head is in contact with the magnetic tape, the other rotating magnetic head is also in contact with the magnetic tape. As a result, when one rotary head plays back information and the other rotary head records information (for example, after-recording), the information on one side overlaps with the other information, noise increases, and the accuracy is reduced. It may become difficult to record and reproduce information. Therefore, when reproducing information using one rotary head and recording information using the other rotary head, it is preferable to reproduce information from areas B or C located in the center and record to area A or D. . For example, when recording 4-channel audio signals using standard frequency sampling, for example, during the first recording, areas A and D (or areas B and C
) are paired as left and right signals, R and front and back signals F and B are recorded. During the second recording, areas B and C (or areas A and D) are recorded.
It is preferable to record the left and right signals, R, and the front and rear signals F and B as a pair.

Next, an embodiment of the PCM encoder 13 will be described.

For example, as shown in FIG.
It can be configured by a D converter 41 and a memory 42. The A/D converter 41 receives the input left and right signals, R,
The analog signal is converted into a digital signal according to a clock of a predetermined frequency (96 kHz in the embodiment) and stored in the memory 42. The signals stored in the memory 42 are read out according to a clock of the same frequency. At this time, for example, if the data read out at odd-numbered clocks is recorded in area A, and the data read out at even-numbered clocks is recorded in area B, the data recorded in each area can be sampled. The frequency will be 7 in 48.

FIG. 9 shows a PCM decoder 12 that decodes such a signal.
represents an example of In this example, the reproduced signals from areas A and B (48K signals with a phase shift of 180 degrees from each other) are used.
The signals sampled by the Hz clock are added by the adder circuit 51 to become a substantially 96 kHz sampling signal, which is then input to the D/A converter 52. A 96 kHz clock is input to the D/A converter 52, and a digital signal read out according to this clock is smoothed by a low-pass filter 53 and output as an analog signal.

However, configuring the encoder and decoder in this way requires a high frequency (96 kHz in the embodiment) clock. Therefore, in the present invention, similar operations are realized in encoders and decoders as shown in FIGS. 7 and 10.

That is, in the encoder shown in Fig. 7, 48kHz
A/D converter 41 and memory 42 that operate with the clock of z
Two systems (A, B) are available.

The A/D converter 41B and memory 42B have an A/D converter 41B and a memory 42B.
48kHz supplied to converter 41A and memory 42A
z clock (FIG. 8(b)) is supplied after being delayed by 180 degrees by the delay circuit 43 (FIG. 8(C)).

Therefore, for example, a predetermined analog signal (FIG. 8(a)) is sampled by 48 kHz sampling pulses having a phase difference of 180 degrees, and each signal is recorded in the area A. As a result, the original signal is essentially 96kHz
This is equivalent to sampling at the frequency z.

Further, in the decoder shown in FIG. 10, two systems (A, B) of D/A converters 52 which operate with 48 and 7 clocks are prepared. The outputs of the D/A converters 52A and 52B are supplied to a sample hold circuit 54, and the output thereof is further output to a low pass filter 53. A 48kHz clock is input to the D/A converter 52A,
The clock is input to the D/A converter 52B after being delayed by 180 degrees by the delay circuit 55. Further, a clock delayed by 180 degrees from this clock is supplied to a sample hold circuit 54. For example, the reproduced signal from area A is converted from a digital signal to an analog signal by the D/A converter 52A (shown by a solid line in FIG. 11), and the reproduced signal from area B is converted from a digital signal to an analog signal by the D/A converter 52A.
B converts the digital signal into an analog signal (
(indicated by a broken line in FIG. 11) is input to the sample and hold circuit 54. The sample and hold circuit 54 sequentially samples and holds, for example, the level aLt am l a□ of the output of the D/A converter 52A using a clock that is not delayed, and also samples and holds the output of the D/A converter 52A in response to the delayed clock.
B output levels b□t b2, etc. are sampled and held sequentially. The combined output is smoothed by a low-pass filter 53, and the original signal (indicated by a dashed line in FIG. 11) is reproduced.

By preparing two systems of 48 kHz encoders or decoders in this way, it is possible to substantially record and reproduce a 96 kHz sampling signal without preparing a 96 kHz clock and its encoder or decoder.

In addition, the signal encoded by the encoder as described above and recorded in each area A or B is reproduced for each area, and the 48
If you decode it with a kHz decoder.

Of course, it is possible to reproduce a 48 kHz sampling signal.

〔effect〕

As described above, the present invention provides an information recording and reproducing apparatus that converts an analog signal into a digital signal and records and reproduces it on a recording medium, in which two systems of encoders or decoders that operate with the same frequency clock are provided, and one encoder or decoder is driven. Since the phase of the clock and the phase of the clock driving the other encoder or decoder are shifted by 180 degrees from each other, higher quality audio signals can be enjoyed in a device that operates with a lower frequency clock.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the magnetic recording/reproducing apparatus of the present invention, and FIG.
The figure is a schematic plan view of the track, FIG. 3 is a schematic plan view of the area, FIG. 4 is a schematic plan view of the track in a conventional magnetic recording/reproducing device, and FIGS. 5 and 8 are according to the present invention. FIGS. 6 and 7 are block diagrams of the PCM encoder, FIGS. 9 and 10 are block diagrams of the PCM decoder, and FIG. 11 is a schematic diagram of the output signal. FIG. 1...Rotating magnetic head 2.3, 6, 7, 21.34...Switch 4...Recording amplifier 5...Reproducing amplifier 8...Video modulator 9.13...PCM encoder 10 ... Video demodulator 11.12 ... PCM decoder 14.23 ... Oscillator 15.25 ... Motor 16.26 ... Frequency generator 17 ... Pulse generator 18.31 ... Drive circuit 19.27... Frequency control circuit 20.29... Phase control circuit 22... Synchronization separation circuit 24.30... Addition circuit 28... Branch circuit 32... Tracking control circuit 33... ... Central processing unit 35 ... Pilot signal generator 41 ... A/D converter 42 ... Memory 43.5
5...Delay circuit 51...Addition circuit 52...D/A converter 53.
...Low pass filter 54...More than sample hold circuit

Claims (1)

[Claims] In an information recording and reproducing device that converts an analog signal into a digital signal and records and reproduces it on a recording medium, two systems of encoders or decoders that operate with clocks of the same frequency are provided, and the phase of the clock that drives one of the encoders or decoders is An information recording/reproducing apparatus characterized in that the phases of the clocks that drive the encoder or decoder and the other encoder or decoder are shifted by 180 degrees from each other.