JPH0463461B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to digitizing an audio signal (main signal) such as an audio signal and recording and reproducing it using a fixed head. The present invention relates to a data recording and reproducing apparatus that records data such as the beginning of a song, address, etc., on a track different from a main signal recording track.

BACKGROUND TECHNOLOGY AND PROBLEMS For example, when an audio signal such as a voice signal is digitally coded (for example, converted to PCM) and recorded on a magnetic tape in a compact cassette using a fixed head, a multi-channel fixed head is used as the fixed head. multiple data tracks T ₁
A data recording and reproducing apparatus (digital audio tape recorder (DAT)) has been proposed that simultaneously records audio signals on audio signals up to Tn (for example, n=20) and reproduces a predetermined audio signal from the audio signals.

An example of this DAT tape format is shown in the first example.
As shown in the figure. The figure shows the tape format for reciprocating playback (double-sided playback), with two tracks on each side for data recording. A magnetic flux responsive thin film head with a multi-channel configuration is used as a fixed head for data recording and reproducing.

In addition to track Ti for recording main data, you can also use
Auxiliary data recording track that stores auxiliary data related to the music signal, such as address, song time, etc.
Ta and Tb are provided.

Auxiliary data can be broadly divided into auxiliary data AMS, which must be reliably reproduced even when the tape is running at a speed different from the data recording speed, for example, 30 times the constant speed, and auxiliary data AMS, which is necessary only for constant speed playback. There is an auxiliary data SUB. The former auxiliary data AMS includes, for example, data for determining the presence or absence of a song, and the auxiliary data SUB includes the number from the beginning of the tape of the song, the time from the beginning of the tape, the time within the song, and the number of songs. Index (track name, performer name, etc.),
This is data indicating emphasis characteristics, copy prohibition, etc.

In some cases, the latter may include data indicating the beginning of the song. This is because there are times when it is necessary to find the beginning of a song even in constant speed driving mode. In the following explanation,
This is an example in which song cue data is also included.

In order to record these different types of auxiliary data AMS and SUB, in principle there are two tracks for recording auxiliary data (Ta,
Tb) Must be provided.

However, since the tape width of audio cassette tape is very narrow at 3.81 mm, when two auxiliary tracks Ta and Tb are provided, the number of main tracks Ti for recording main data must be reduced, or the track pitch itself must be changed. must be narrowed. Reducing the number of main tracks Ti is unfavorable in terms of sound quality, etc., and narrowing the track pitch causes difficulties in manufacturing the fixed head. Taking these points into consideration, it is better from the viewpoint of sound quality and fixed head manufacturing to reduce the number of main tracks Ti, which have a predetermined track pitch, by reducing the number of main tracks Ti by reducing the number of auxiliary tracks to one, as shown in Figure 2. preferred.

Furthermore, when two auxiliary tracks are used, the number of channels for the recording system, the reproducing system, and the fixed head for recording and reproducing increases accordingly, which increases the circuit scale, etc., and becomes a factor in increasing costs.

Purpose of the invention Therefore, in this invention, one auxiliary track
First auxiliary data D required only during high-speed playback
-AMS and second auxiliary data D-SUB required only during constant speed playback can be recorded, and each data can be reliably played back according to the tape speed.

Summary of the Invention Therefore, in the present invention, first auxiliary data D-AMS and second auxiliary data D-SUB, which are digital code signals, are combined and recorded. 1st
A low bit frequency is used for the auxiliary data D-AMS, whereas the second auxiliary data D-AMS uses a low bit frequency.
A high SUB bit frequency is used.
Then, during data synthesis, the first auxiliary data D-
When AMS indicates one piece of information, the second auxiliary data D-SUB is phase inverted and DC
It is synthesized in a shifted state.

When playing data, the second auxiliary data D-SUB
The first auxiliary data D-AMS is obtained from the DC shift component of
is extracted and separated.

Embodiment Next, an example of the present invention applied to a DAT will be described in detail with reference to FIG. 3 and subsequent figures.

Figure 3 shows an example of DAT10.
A indicates a recording system, and 10B indicates a reproduction system.

In the case where a stereo audio signal is used as the audio signal, the left and right audio signals S _L and S _R supplied to terminals 1R and 1L are converted into digital code signals by the A-D converter 2. , is supplied to an encoder 3 for encoding processing, and is supplied to a digital modulator 4 for digital modulation. For digital modulation, a phase modulation (Biφ-L) method or the like may be used.

The digitally modulated main digital code signal is distributed from the first channel to the 20th channel in this example, and then distributed to the corresponding recording amplifier 4.
Head H _M1 for recording and playback via A ₁ to 4A ₂₀
H _M20 and the corresponding main tracks T ₁ to _{T 20}
are recorded simultaneously. 5 indicates a recording tape.

On the other hand, the first auxiliary signal S-AMS, which needs to be reproduced in the high-speed reproduction mode, is transmitted through the terminal 7, and the second auxiliary signal S-SUB, which must be reproduced only in the constant-speed reproduction mode, is transmitted through the terminal 8. are supplied to the signal conversion circuit 30 via the respective signals. As will be described later, in this signal conversion circuit 30, the first and second auxiliary signals S-AMS and S-SUB are converted into predetermined digital code data, and are combined after being subjected to predetermined signal processing. is output. This composite data AD is supplied to the head Hs via the recording amplifier 14 and recorded on the auxiliary track Ta in relation to the main digital code signal.

In the reproducing system 10B, signal manipulations that are opposite to those in the recording system 10A may be performed, so a detailed explanation thereof will be omitted.

15A ₁ to 15A ₂₀ and 16 are playback amplifiers, 17
is a digital demodulator, 19 is a decoder, and 21 is a D/
A converter with terminals 22R and 22L,
Analog audio signals _SR and _SL are obtained. Also, 50
is the inverse conversion circuit of the composite code AD, and the terminal 5
1A is the first auxiliary signal S-AMS, terminal 51B
A second auxiliary signal S-SUB is obtained.

FIG. 4 shows an example of the signal conversion circuit 30, in which the first auxiliary signal S-AMS is transmitted via the terminal 7 to the first auxiliary data (digital code signal) D-
It is supplied to the generator 31 of the AMS. The first auxiliary data D-AMS indicates that the tape speed is constant (4.76 cm/
bit frequency (according to the NRZ recording method, approximately 2K
Hz), and the code "101010" is repeatedly output within one song, for example. Between songs, the code "11001100", for example, is repeatedly output at twice the frequency mentioned above.

On the other hand, the second auxiliary signal S-SUB is transmitted via the terminal 8 to the second auxiliary data D-SUB having a 4-bit configuration, for example.
The signal is supplied to the generator 32 of the SUB.

The second auxiliary data D-SUB is selected to have a bit frequency that provides a recording density of, for example, 60 KBPS or more in the constant speed running mode.

The second auxiliary data D-SUB is further supplied to a code converter 33 where the 4-bit data is converted into DC-free bit data, in this example 8-bit data. In this case, as shown in FIG. 6A and B, the first auxiliary data D
- Code conversion data that always sets "1" as the first and last data when inverting AMS is used. FIG. 6B shows an example of the second auxiliary data D-SUBM after code conversion.

Code-converted second auxiliary data D-
The SUBM and the first auxiliary data D-AMS are supplied to a multiplier 34 to perform multiplication processing of digital code signals. As a result of this multiplication process, only when the first auxiliary data D-AMS is in one state, that is, in the inverted state of "0", the composite data AD as a multiplication result is transferred to the second auxiliary data D-AMS as shown in FIG. The contents of the auxiliary data D-SUBM are obtained in an inverted state and DC-shifted to the negative side. Therefore, the composite data AD has three levels.

This is merely an example, as the data waveform shown in FIG. 6C can be formed without the use of multiplier 34.

This composite data AD is recorded on tape 5.

Note that 37 is a frame sync F-SYNC generator, and the frame sync F-SYNC is inserted every block (8×98 bits) of the second auxiliary data D-SUB. This frame sync F-SYNC
is also transcoded.

FIG. 5 is an example of the signal inverse conversion circuit 50.

The synthesized data AD reproduced from the head Hs is transmitted to the first inverse conversion system 50A and the second inverse conversion system 50A via the reproduction amplifier 16.
and an inverse conversion system 50B. The first inverse conversion system 50A is for reproducing the first auxiliary signal S-AMS, and as described above, the data for locating the beginning of the song is inserted into the sub-block of the second auxiliary data D-SUB. In such a case, there is no particular need to reproduce the first auxiliary signal S-AMS from the first inverse conversion system 50A in the steady running mode.
Therefore, the regeneration operation in the high-speed running mode will be described below.

In a high-speed running mode in which the vehicle travels at N times the constant speed (N is approximately 1 to 30), the cutoff frequency of the low-pass filter 52 is controlled to be N times or more the bit frequency of the first auxiliary data D-AMS. This control is performed based on data Tc that detects the tape speed. This is because the tape speed can be set to any speed between constant speed and N times speed, and the bit frequency to be extracted changes depending on this tape speed.

Therefore, the envelope output of the composite data AD can be obtained from the low-pass filter 52 at any tape speed. The composite data AD is the second auxiliary data D- as shown in FIG. 6C.
Since SUBM is modulated by the first auxiliary data D-AMS, the low-pass filter 51
The first auxiliary data D-AMS, which is a modulation signal, is
The envelope output will be obtained.

The output of the low-pass filter 52 is supplied to a waveform shaping circuit 53 having three levels, "1", "-".
After being shaped into a 1” waveform, the data detector 55
supplied to Therefore, a digital PLL 56 is provided, and a clock CK synchronized with the input is supplied to the data detector 55. Its output is decoder 5
8 to reproduce the original first auxiliary signal S-AMS.

This first auxiliary signal S-AMS is supplied to a CPU (not shown) to display its contents and control the tape transport system.

On the other hand, the second inverse conversion circuit 50B is for reproducing the second auxiliary data D-SUBM during the constant speed driving mode, and the composite data AD is directly supplied to the equalizer amplifier 62 to prevent intersymbol interference. is removed. The waveform of the second auxiliary data D-SUBM outputted from the equalizer amplifier 62 is shaped into a digital code signal by a waveform shaping circuit 63 configured in the same manner as described above, and its output is supplied to a selective inverter 64. be done.

This selective inverter 64 is shown in FIG. 6C.
It is for returning the DC-shifted digital code signal to its original state, and can be composed of, for example, a "-1" constant and a multiplier. Since this inverter 64 is selective, in the case of a digital code signal of "1", it is output as is.
The output of inverter 64 is supplied to data detector 65 and digital PLL 66. The output is inversely converted from an 8-bit digital code signal to a 4-bit digital code signal by a code converter 67, and the second auxiliary data D-SUB outputted from this is supplied to a decoder 68 and converted to the original second auxiliary signal S
-SUB is played.

The reproduced second auxiliary signal S-SUB is also supplied to the CPU, and the corresponding contents (song address, playing time so far, emphasis characteristics, etc.) are displayed, and the tape transport system corresponding to the contents is displayed. is controlled.

In addition, in the constant speed driving mode, the first auxiliary signal S
-AMS is not played, but since the data for locating the beginning of the song is included in the second auxiliary data D-SUB, locating the beginning of the song can be executed even in the constant speed driving mode.

When the bit frequency of the second auxiliary data D-SUB is made higher than the above value (60KBPS), the second auxiliary data D-SUB shown in FIG.
The first auxiliary data D-AMS can be reproduced even if the digital code signals at the beginning and end of SUB do not necessarily correspond to "1".

Effects of the Invention As explained above, in the present invention, the first auxiliary data D-AMS that must be reproduced in the high-speed driving mode and the second auxiliary data that must be reproduced only in the constant-speed driving mode. D-SUB is frequency-multiplexed and recorded on one auxiliary track Ta, and desired auxiliary data can be extracted and separated from this, so it has the following characteristics.

First, the sound quality is excellent because the number of main tracks Ti is not reduced. The track width of the main track Ti can also be made wider due to the absence of the auxiliary track Tb. This facilitates the manufacture of the fixed head. Since the circuit scale of the recording system and the reproducing system can be reduced, the cost of the DAT10 can be reduced by combining the above-mentioned advantages.

If technological advances make it possible to easily manufacture a multi-gap fixed head that can accommodate the number of tracks shown in Figure 1, then the auxiliary track Tb
Since different information can be recorded in the memory, it is easy to increase the number of function modes.

The second auxiliary data D-SUB is obtained by inverting and DC shifting the digital code signal of the first auxiliary data D-AMS only when the digital code signal is in the same state.
The first and second auxiliary data D-AMS, D-
It is possible to reliably extract and separate SUB.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of tape patterns;
FIG. 3 is a block diagram showing an example of a data recording/reproducing apparatus according to the present invention, FIG. 4 is a block diagram showing an example of an auxiliary data signal conversion circuit, and FIG. 5 is a block diagram showing an example of the signal inverse conversion circuit. Figure, 6th
The figure is a diagram for explaining the operation. 30 is a signal conversion circuit, 50 is a signal inverse conversion circuit,
D-AMS and D-SUB are first and second auxiliary data.

Claims (1)

[Claims] 1. A first bit rate converted with a first bit rate.
and second digital data converted with a second bit rate faster than the first bit rate, and only when the first digital data is in the same state, the second digital data is means configured to DC shift the synthesized digital data; means for recording the synthesized digital data on a recording track; means for reproducing the synthesized digital data from the recording track; A data recording/reproducing device comprising means for separating first and second digital code data.