JPS6398878A - Digital signal recording method - Google Patents

Abstract

PURPOSE:To record a high transmission rate multi-channel audio PCM signal onto a video signal area continuously for a long time by recording a digital signal while applying time compression and area split at recording in recording a digital audio signal by means of a rotary magnetic head scanner. CONSTITUTION:The modulation demodulation system having less high frequency component and less DC component and/or low frequency component is adopted as a surface layer modulation system, and in case of less high frequency component, multi-channel by compression is applied and in case of less low frequency component, the simultaneous use of the deep layer recording method is attained. A 2-channel analog signal is inputted from an input terminal 1 at recording and prescribed band limit is applied by a filter 3, converted into a PCM signal by an A/D converter 6 and written in a RAM15. The read rate and timing from the RAM15 are controlled to provide compression and delay of time base, and the recording/reproducing time is made long by recording the audio signal also to the video signal area.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides a method for converting encoded digital audio signals into a rotating magnetic field.
The present invention relates to an apparatus for recording on a magnetic tape using a rad scanner, and particularly to a recording method suitable for long-term continuous recording.

[Conventional technology]

Conventional equipment for recording and reproducing audio signals using a rotary head scanner uses a consumer PCM encoder/decoder: CPZ that records and reproduces audio PCM (ff) instead of video signals.
-105: There is something determined by the Japan Electronics Industry Association's technical foundation.

This method is based on a video signal format and records a digital signal in a video signal area.

[Problem that the invention seeks to solve]

In the above conventional technology, the audio PCM signal is recorded with the same head and under the same conditions as the video signal head, and when recording the audio PCM signal in the video signal area, there is no need to make any arrangement related to the recording conditions. Ta.

An object of the present invention is to provide a recording method for recording a high transmission rate multi-channel audio PCM signal in a video signal area.

[Means for solving problems]

The above object is achieved by employing a modulation/demodulation method with less high-frequency components, less DC components, and/or less low-frequency components as a modulation method for the surface layer.

[Effect]

When there are few high frequency components, multi-channeling by compression is shown in FIG.

When there are few low J) components, it becomes possible to use it in combination with the deep recording method.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

This embodiment relates to an audio-only recording and reproducing system that records an audio signal instead of the video signal in a rotating head/recursive scan type recording and reproducing apparatus that records video signals and PCM audio signals.

Here, an explanation will be given based on an apparatus that records a video signal on the surface and a PCM audio signal on the deep layer.

This will be explained below with reference to FIG.

During recording, for example, two R channels of analog signals are input from the input terminal 1. The input signal is amplified to a predetermined level by an amplifier circuit 2, band-limited to a predetermined value by a filter 3, and then sampled by a sample hold circuit 4. The sampled input signals are alternately input to an A/D converter 6 by a switching circuit 5 and converted into a PCM signal. The signal converted by the A/D converter 6 is sent to the RAM 15 through the path line 14.
will be written to. Then, according to a predetermined format, the arrangement of the PCM signal and the addition of the error l] positive code are performed. Note that the error correction code is added using the error correction circuit 2o. I) After placing the CM code and adding the error correction code, each data is read out from the RAM 15. Writing, arrangement, addition of correction codes, and reading of these PCM signals are performed by controlling the address of the RAM 15 by the address generation circuits 17 to 19 and the address generation circuit 16. At this time, the read address generation circuit 19 uses the in-field sample number correction circuit 36 to
The number of audio signal samples in the field is determined by the number of samples in the field based on the signal determined by the difference determination circuit 34 from the difference between the write address and the read address extracted by the address difference extraction circuit 33. Control is performed to achieve the sample regime set by the setting circuit 35. The signal read from the RAM is converted into a serial signal by the parallel-to-serial conversion circuit 23. Then, the control signal circuit 24 and the switching circuit 25
As a result, signals other than audio and control signals such as synchronization signals are added and modulated by the surface recording modulation circuit 37-1 and the deep recording modulation circuit 37-2. Then, it is amplified to a predetermined level by the recording amplifier 26-1 for surface recording and the recording amplifier 26-2 for deep recording. recorded. The switching circuits 46 and 47 are for switching between recording and reproduction, and the switching circuit 49
is used to switch between audio-only recording and reproduction and video and audio recording and reproduction. Further, the timing generation circuit 21
This circuit generates a timing signal that controls the entire system using an IC clock generated by the oscillation circuit 22 and a head switching signal determined by the scanner phase.

During reproduction, the switching circuits 46 and 47 are switched to the reproduction side, and the signals reproduced by the video rotary head 43 and the audio rotary head 31 are transferred to the surface recording preamplifier circuit 29.
-1 and a preamplifier circuit for deep recording 29-2 to a predetermined level, and a waveform equalization circuit for surface recording 39-1.
Waveform equalization is performed by the deep recording waveform equalization circuit 39-2.

This waveform-equalized signal is sent to the surface recording demodulation circuit 38-
1 and a deep recording demodulation circuit 38-2, the signal is demodulated and converted into a digital signal. The demodulated digital signal is sent to the switching circuit 48. Synchronous detection circuit 28 and direct conversion circuit 27
The synchronization signal is detected and converted into a parallel signal. The detected synchronization signal is input to the timing generation circuit 21 and used as a reference for data reproduction. The data converted into parallel signals is determined by the signal determination circuit 44 as to whether it is an audio signal and the same parity or a signal other than audio, and the audio signal and the same parity are stored in the RAM 15, and the data arrangement and error correction circuit Error correction is performed according to 20. Data subjected to error correction processing is read out from the RAM 15 and input to the D/A converter 12 through the pass line 14. Writing to this RAM 15, correction processing,
Reading from RAM 15 is performed by address generation circuit 1.
RAM1 by 7 to 19 and address switching port vrL 6
This is done by controlling the address of 5.

The data converted into an analog signal by the D/A converter 12 is sent to the sample hole I and resampled for each channel by the circuit 11. Analog signals resampled in each channel are outputted from an output terminal 8 through a filter 10 and an amplifier circuit 9. Next, when recording a video signal on the surface of the magnetic tape 32 and recording and reproducing video and audio, the video signal is inputted from the input terminal 40 and converted into a predetermined signal by the video circuit 12 during recording. , the switching circuit 49 switches to the video side, and the video rotating head 43
is recorded on the surface layer of the magnetic tape 32. During reproduction, the signal reproduced by the video rotating head 43 is
It is converted into a predetermined signal by the video circuit 42 and sent to the output terminal 4.
Output from 1.

With such a +14 configuration, the audio signal is also recorded in the video signal area for audio-only recording, thereby lengthening the recording and reproducing time.

Furthermore, by controlling the read rate and read timing from the RAM 15 by the timing generation circuit 21, companding and delay on the time axis can be applied, and compressed recording and playback can be performed for each channel.

The operation of the present invention will be explained in more detail below using waveform diagrams.

FIG. 2 shows a diagram in which a formatted PCM audio signal is time-compressed to, for example, 1/4 or less, a video signal track is divided into, for example, four, and the time-compressed PCM audio signal is divided into the four divided video (track number 1). FIG. 4 is an operation waveform diagram related to a recording method.

As will be explained below with reference to the drawings, for example, an AGB 2-channel signal as an analog human input signal is converted into PCM and then converted into a predetermined format.

C indicates a data group corresponding to one field period of a formatted signal, and each field is i, i+1, . ... and divide sequentially.

Next, for example, the i-th data group of "1" is 1/
Compress the time to 4 or less.

The time-compressed data is recorded on the top five layer 1-rack of the first channel by a video head of one azimuth as indicated by f. Similarly, the data group 1+] is recorded on the surface layer 1-rack of the second channel by the +azimuth video head.

The upper +2 data group is recorded on the surface track of the third channel by the -azimuth video head.

The i+3 data group is recorded on the surface track of the 11th channel by the +azimuth video head.

Next, data 11G of j+4 is deeply recorded by an audio head of -azimuth as shown in e.

Next, the 1+5 data group is recorded on the surface track of the first channel by the +azimuth video head. Here, the data group i-1 in e of the figure is deeply recorded by the +azimuth audio head.

As described above, the azimuths of adjacent tracks can be reversed for both the deep track and the surface track.

FIG. 3 shows an example of a tape pattern recorded by the above-described operation. In the figure, the broken line area indicates the deep track arrangement, and the hatched area indicates the area recorded with +azimuth.

In the figure, 1.2.3 and 4 indicate channel numbers.

Next, the operation when a signal recorded as shown in FIG. 3 is read out will be explained with reference to the waveform diagram in FIG. 4.

The explanation will be given below according to the figures.

a indicates the head switching signal, and + indicates +azimuth.

- indicates -azimuth. b is the reproduced output waveform from the video head, i, i+1 . ...is the i-th,
The output waveform of the i+1th data group, . . . is shown. C is the playback output waveform from the audio head, i-1, i+
4. ... is the i-1th one.

The output waveform of the i+4th data group is shown. d indicates a selection signal of the video head reproduction output signal. e indicates a selection signal of the head reproduction output signal for Audifo. f indicates the sum signal of the signals selected by both the d and e signals.

In FIG. 5, a 180° surface recording track for recording a video signal is divided into odd number channels, for example, three channels, and the tape feeding speed is set to 1/3. FIG. 2 is a waveform diagram showing the operation of the embodiment in which `i is recorded. The explanation will be given below according to the figures.

As analog input signals, for example, two-channel signals a and b are converted into PCM and then converted into a predetermined format. The formatted signal, like C, is divided into fields i, i+1 . It is divided into data groups such as... Each data group is time-compressed to 1/3 or less as shown in d, and is delayed with a period of 3 data G'C. Here, the reason why the one-time compression is set to ⅓ or less is to secure a margin between adjacent channels and an area for adding a clock lead-in signal, for example. For example, e indicates a head switching signal, and + and - indicate the azimuth of the head, respectively.

In this way, the data group compressed by 1/3 time of i-1 is transferred to the third channel (area 3) by the +azimuth head.
recorded in Similarly, i is connected to the first channel (area 1) by one azimuth head, i+1 is connected to the second channel (area 2) by +azimuth head, and i+2 is connected to the third channel (area 3) by -azimuth head. ) to,
j+3 is sequentially recorded in the first channel (area 1) by the +azimuth head.

The state recorded with the above timing.

This will be explained using the tape pattern shown in FIG.

The hatched area in the figure shows a data group recorded at -azimuth. As shown in the figure, adjacent tracks such as i and i+3 can be recorded at different azimuths.

FIG. 7 shows the recording operation on the tape. When recording at a tape speed of 1/3 as shown in the figure,
After recording the data group i+1, the data group i+4 is recorded three tracks later, and as a result, the track width of i+1 becomes the same as the track width during normal operation.

Next, the operation when reading out the signals recorded as described above will be explained with reference to the waveform diagram of FIG. The explanation will be given below according to the figures.

a indicates the head switching signal, and 10 indicates +azimuth.

- indicates one azimuth. b is the reproduced output waveform, i
, i+1. ... are the 1st, i+1st, etc., respectively.
The output waveform of the data group is shown. C indicates a selection signal of the reproduced output signal. d indicates the reproduced signal selected by C.

Next, the operation in the timing generation circuit 21 will be explained in the ninth section.
This will be explained using the waveform diagram in the figure.

a is the original clock waveform, b is the head switching signal (-
) and (+) respectively indicate the azimuth angle of the head in contact with the tape.

C, d He , f and g indicate waveforms obtained by dividing the original clock a.

The frequency-divided output is decoded to generate j and 1. Here, h is a pulse at a timing corresponding to the falling edge of C, and is generated by decoding the frequency-divided output as described above.

k is the field period divided into three.

Here, the formatted signal is time-compressed on a field-by-field basis using the signal i as a reference and output.

For this purpose, the read address generation circuit is driven by the signal i. The drive region is denoted by p.

With the above driving operation, for example, in k, as shown in the numbers in the O frame, one channel is recorded by one azimuth head, the second channel is recorded by the + azimuth head, and the third channel is recorded by the -azimuth head. Then record again on channel 1 using the +azimuth head.

As a result, 1 azimuth head and + azimuth head are alternately recorded in one channel, for example.

Other channels are also recorded alternately.

Next, the circuit configuration of the control signal generation section in the timing generation circuit 21 is shown in FIG.

The explanation will be given below according to the figures.

The original clock from the original clock input terminal 55 is sent to the frequency dividing circuit 5.
7 to the clock input and latch circuit 59.

The synchronization signal from the switch changeover signal input terminal 56 is input to the synchronization signal input of the frequency dividing circuit 57.

The frequency divided output of the frequency dividing circuit 57 is input to the decoding circuit 58.

The decode output of the decode circuit 58 is input to the launch circuit 59.

The latch output of the latch circuit 59 is output to the output terminal 60.

In the frequency dividing circuit 57, for example, a in FIG. 9 is input as the original tarokku, and the output is b+c+d.

Qj f+ g and h generation signals are output.

The output of the frequency dividing circuit 57 is decoded by a decoding circuit 58 and then latched by a latch circuit 59 to output control signals i and j.

Next, compression will be explained in more detail. In this embodiment, 4-channel compression recording will be explained.

During four-channel recording, since the recording pattern of each channel is discontinuous, a clock pull-in signal and a margin area between adjacent channels are required for each channel. Therefore, for example, it is compressed to 1/4 or less and a margin area is provided. This pattern is shown in FIG.

In the above embodiments, the case where the rotating head scanner is operated at the same number of rotations as when recording a video signal has been described, but an example will be described in which the number of rotations is doubled and recording is performed. .

FIG. 12 is an operational waveform diagram, and FIGS. 1 and 3 are tape pattern diagrams. The following explanation will be given based on both figures.

a is a PCM audio signal divided into fields. b is a frame period pulse. C is a head switching signal when the rotating head is set to double speed. In the figure, + and - indicate head azimuth. d is a time-compressed and delayed signal of a. In this embodiment, a case of three-channel recording will be explained. In this case, the time compression is 1
/6 or less, and the delay is first the 1st and 2nd with +azimuth head.
Then, the quality is recorded on the 3 channels, and then the -azimuth head is used to alternately record on the 1st, 2nd, and 3rd channels.

The tape pattern recorded in this manner is shown in FIG. In the figure, 1, 2 and 3 indicate channel numbers,...
i, i+1. . . corresponds to a signal recorded by d, which is a compressed version of a in FIG. 12, and the hatched area is an area recorded with +azimuth.

In this way, since recording can be performed with changing the azimuth for each track, adjacent tracks can have different azimuths.

FIG. 14 shows a modulation circuit, demodulation circuit, or modulation/demodulation circuit.

Figure 14(a) shows the surface layer and deep layer circuits 14-1.14.
2 is an example of a configuration in which the modulation/demodulation circuit 14-2 is made independent, and FIG. For shared circuits, change the circuit specifications to the front/deep switching signal]4-4
The selection is made according to

FIG. 15 shows the configuration of the reproduction system in the method in which the -1-rack is divided into a plurality of tracks. 15th
[1d(a) is a demodulation circuit 15 for each divided track.
- A configuration using signal processing circuits 15-1 to 3 and signal processing circuits 15-6 to 15-8, FIG. The same figure (c) shows the demodulation circuit 15-5 and the signal processing circuit 15-5.
This is an example of the configuration when 12 is used in common.

As described above, when the modulation methods for the deep layer and the surface layer are made the same, it is possible to simplify, standardize, and share the circuit by simply changing the portions depending on the difference in carrier wave and band.

FIG. 16 shows the recording pattern on the tape. Depending on this recording method, there are multi-track mode and long-time mode.

In the multi-track mode, the tape speed is normal, and recording is performed from the TRI area to the TR3 area in one sweep of the track.Therefore, recording is performed on the same track with the same azimuth. In this case, the number of recording and playback channels is 3.
For example, it is possible to record six channels of signals simultaneously. moreover.

It is also possible to record in the order of TRI, 2 and 3.

Next, the long-time mode is a method in which one of TRs 1 to 3 is recorded in one sweep of the track. For example, by reducing the tape speed to 1/3, the recording density can be made the same. In this case, if the order is TRI, then 2.3, the azimuth will also change sequentially, and therefore adjacent tracks in the tape running direction will have normal azimuth. Also, in the same figure, the audio-only track is Audio, and the tracking track is C.
It is indicated by TL, and the tape width etc. are indicated by A, R, C, and W, respectively.

FIG. 17 shows recording states in multi-track mode and long-time mode. In the multi-track mode, it is possible to simultaneously record in areas of TR2 and TR3 in addition to the area shown in Figure 1.

FIG. 18 shows the arrangement within the track, and FIG. 19 shows the signal name, content, and area recorded within the track in terms of angle. In the figure, 525/60 indicates the NTSC system, and 625150 indicates the CCIR system.

FIG. 20 shows the frequency spectrum of the audio 1) CM signal. In the deep layer, a digital signal of approximately 2.45 Mbp is modulated into PSK, QPSK, QDPSK, or ○QDISK and recorded in the audio pcbi times signal equivalent to DAT. The figure shows the frequency spectrum of a signal modulated by 0QDPSK with a carrier frequency of 2M1lz. Next, in the surface area, that is, the area where the normal video signal is recorded, a digital signal with a bit rate of approximately 7.4 Mbps, which is three times the audio PCM signal equivalent to DAT, is transmitted using PSK, QPSK, QDPSK, or ○Q.
Record with DPSK modulation.

In the figure, OQ D at carrier frequency 5 + 5 M ltz
The frequency spectrum of the PSK modulated signal (the frequency spectrum is shown by the solid line PSK).

iFM is the frequency spectrum when a signal at the same rate is subjected to FM modulation similar to 8mVideo audio PCM, and the chain line 8-10 is the frequency spectrum when the signal to i-1 is subjected to 8-10 modulation similar to DAT. This is the frequency spectrum when FM contains many high-frequency components, which causes problems in notes A and J.

8-10 contains a lot of low-frequency components, causing interlayers such as Talostok and others, and is problematic when used in combination with 1) SK. In contrast, I)SK modulation is superior in terms of bandwidth. Here, the carrier wave frequency and band can be set to optimal values according to the characteristics of the transmission path.

As mentioned above, by using both the deep layer and the surface layer, V HS
In the case of NTSC and EP mode, in the long mode, 3 times the 8 hours in the surface layer and 8 hours in the deep layer, for a total of 32 hours of recording and playback, or in the multi-channel mode, 2 channels (or 4 channels) in the surface layer. A total of 8 channels (or 1G channel) can be recorded and played simultaneously, including 2 channels (or 4 channels) in the deep layer.
These are numerical values for 4-channel mode.

Furthermore, if you record it in advance on a deep layer or a certain track,
Sequentially to the surface layer based on the playback signal of <8 recorded on the deep layer or track! It is also possible to record 11, in which case 1, for example, TRI to 3 are simultaneously recorded.
1, TR2, and TR3 are recorded independently.
I' is also possible.

In addition, it is also possible to perform an operation of recording a signal recorded in a deep layer or another track by second base.

In addition, h'71':ji also explained an example of recording the audio PC~1 signal, but the deep part is
F 1F in VTR? , similar effects and operations are possible with iVoice.

In addition, the deep part is an audio PCM signal, and the surface part is a consumer PCM signal.
Audio P based on CM encoder/decoder format
It is also possible to record CM (i”7).

In addition, in multi-track mode, audio PCM on each track (even during digital direct recording when the mark source is an independent master clock, it is possible by performing asynchronous absorption processing for each track, Reproduction is also possible in the same way.

In the above embodiment, an apparatus for recording and reproducing an audio PCM signal instead of a video signal (No. 3) was shown, but a description will be given of an apparatus 11 for recording an audio PCM signal as part of a video signal. FIG. 22, which is a diagram showing tracks, is a timing chart showing multiple recording.

The rear part of one field of video signal, for example, 17 of one field.
Record the audio PCM in area 3. For example, an audio PCM signal is recorded in the area TR3 in FIG. 16 of the previous embodiment, and
Areas I and 2 are normal video signals.

This allows the video signal and the audio signal 43 to coexist.6 FIG. 23 shows a display example of the signal recorded in this manner. Information based on the -11 control signal or the like can be displayed on the display section where the video signal is not recorded using the audio signal.

FIG. 24 is a block diagram of the video/sound multiplexing section. The video signal and the audio signal are switched by a switch 24-1, and a multiplexing circuit 24-2 superimposes a synchronization signal on the audio signal. Next, amplifier 24-3. It is recorded on a tape 24-6 by a head 24-5 via a rotary transformer 24-4.

Here, the multiplex circuit 24-2 prevents the video signal synchronization signal from being lost in the audio signal recording area.

This is to stabilize the operation, and it superimposes a synchronization signal with the same timing as the synchronization signal in the video signal, for example, a horizontal synchronization signal.If it is superimposed on the audio No. 48 of the switch 24-1 in advance, the same effect will occur. effective.

〔Effect of the invention〕

According to the present invention, digital audio can be continuously recorded in multi-channel recording.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 2 is an operation waveform diagram of one embodiment of the present invention, and FIG. 3 is a diagram of the second embodiment.
A diagram of a tape pattern recorded in one operation. Fig. 4 is a reproduction waveform diagram of a signal recorded as shown in Fig. 3, Fig. 5 is an operation waveform diagram of another embodiment, and Figs. 6 and 7 are tape patterns recorded by the operation shown in Fig. 5. 8 is a reproduction waveform diagram of a signal recorded as in 6I21, FIG. 9 is an operational waveform diagram in the timing generation circuit 21, and FIG. 10 is a diagram of the control signal generation section in the timing generation circuit 21. A circuit configuration diagram, FIG. 11 is a track pattern layout diagram, FIG. 12 is an operation waveform diagram of another embodiment, and FIG.
The figure is a tape layout diagram, and FIG. 14 is a modulation/demodulation circuit configuration diagram. FIG. 15 is a demodulation/signal processing circuit configuration diagram. FIG. 16 is a 1-rack configuration diagram on the tape, FIG. 17 is a track recording timing diagram, and FIG. 18 is a track arrangement diagram. Figure 19 is a track specification diagram, Figure 20 is an audio PCM signal frequency spectrum diagram, Figure 21 is a tape format diagram, Figure 22 is a video/audio multiplexed signal configuration diagram, and Figure 23 is a display of video/audio simultaneous recording. FIG. 24 is a block diagram of a multiplexing circuit for video signals and audio signals. 6...A/D conversion circuit, 12...D/A conversion circuit. 15...RAM, 21...timing generation circuit, 3
7-1...Modulation circuit for surface layer recording, 37-2...Modulation circuit for deep layer recording, 50...Address difference extraction circuit, 52...
- Number of samples in field setting circuit, 53... Number of samples in field counting circuit, 57... Frequency dividing circuit, 58... Decoding circuit, 59... Latch circuit. Representative Patent Attorney Katsuo Ogawa / Me / Akatsuki 3 Rape Tape (M-Q' (J
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Claims (1)

[Scope of Claims] 1. A digital signal recording method, in an apparatus for recording and reproducing digital signals using a rotating magnetic head type scanner, which is characterized in that the digital signals are time-compressed and recorded by dividing into regions at the time of recording. 2. The digital signal recording method according to claim 1, wherein the digital signal is digital data subjected to phase shift keying modulation.