JPH0568780B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is a method for digitally recording data such as music signals and image signals on a magnetic tape as a recording medium, and for extracting data recorded on the magnetic tape from the magnetic tape. The present invention relates to a digital audio tape recorder that reads and outputs data, and more particularly to a digital audio tape recorder that can perform high-speed dubbing.

<Prior art> In this type of digital audio tape recorder, when data recorded on one magnetic tape is recorded on another magnetic tape, that is, when dubbing, the reproduced signal from the magnetic tape is first converted into analog data. Generally speaking, there are two methods: after conversion, the data is digitized again and recorded on another magnetic tape, and the other method is to convert the reproduced signal into a digital audio interface format and output it, and then record this digital data on another magnetic tape using a recording system. It is used.

<Problems to be Solved by the Invention> However, dubbing using any of the methods described above can only be performed at a constant speed similar to that during normal recording or reproducing operations. That is, according to the former method, the sampling frequency during high-speed dubbing does not match accurately due to analog-to-digital conversion, whereas with the latter method, the reproduced digital data signal is output at a set speed. High-speed dubbing has not been realized due to the lack of an appropriate means for detecting the operating speed on the playback side of the input digital data signal and controlling the operating speed of the recording system in response to this speed. .

<Object of the Invention> The present invention has been made in view of the above-mentioned problems in the prior art. The object of the present invention is to provide a digital audio tape recorder capable of variable speed dubbing by accomplishing two technical tasks: detecting the operating speed of a playback system from data.

<Means for Solving the Problems> In order to achieve the above object, the digital audio tape recorder of the present invention includes a servo circuit that controls the rotational speed of the rotating drum and the capstan, and converts a playback signal into a data signal. a data demodulation circuit that converts an input data signal into a recording signal; and a signal processing circuit that formats the data signal from the data demodulation circuit into a digital audio interface format during playback and unformats the input digital signal during recording. a recording speed calculation circuit that detects the transfer speed and sampling frequency on the playback side from the input digital signal during recording and calculates the clock frequency from these detected values; The present invention is characterized by a basic clock control circuit that variably controls the clock frequencies of the servo circuit, data demodulation circuit, data modulation circuit, and signal processing circuit in accordance with the output values of the arithmetic circuit.

<Function> With the above configuration, when dubbing data from one magnetic tape to another magnetic tape, in the playback operation, if the system speed is set by an external operation such as a panel switch,
The basic clock control circuit varies the clock frequencies of the servo circuit, data demodulation circuit, and signal processing circuit in accordance with this set value. Now, if double speed is set by external operation, the servo circuit will double the running speed of the magnetic tape and the rotational speed of the rotating drum, and the data demodulation circuit and signal processing circuit will operate at twice the normal speed. The signal is processed, converted into a digital audio interface format by a signal processing circuit, and output.

The digital audio tape recorder on the recording side to which this output signal is transferred detects and counts the synchronization signal of, for example, a digital audio interface format from the input digital signal to detect the transfer speed on the playback side. The sampling frequency is detected from the data, and the recording speed calculation circuit calculates the clock frequency during recording based on the detected transfer speed and sampling frequency. This calculation value is sent to the basic clock control circuit to control the signal. The system clocks of the processing circuit, data modulation circuit, and servo circuit are set to double the normal speed, and recording is performed at double speed.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a block configuration of an embodiment of the present invention, in which two recording/reproducing magnetic heads 2 are mounted on a rotating drum 1.
A and 2B are mounted facing each other at an angle of 180° to form a rotary head device. Such a rotating head device is used when data such as music signals or image signals is converted into PCM and recorded on a recording medium and then played back. This is because it requires a wider frequency band than the analog signal before it is converted into an analog signal, and such a wide band signal can be recorded with high density.

A magnetic tape 3 as a magnetic medium is pulled out from a tape cassette 4 onto this rotating drum 1.
It can be wrapped around at an angle of 90°,
The rotating drum 1 rotates in the direction of the arrow at a constant rotational speed V _D , and the magnetic tape 3 rotates at a tape speed V _t that is sufficiently lower than the rotational speed V _D of the rotating drum 1.
It travels in the direction of the arrow, and has a configuration similar to that of a video tape recorder.

The signals reproduced from the magnetic tape 3 by the respective magnetic heads 2A and 2B are sent to the reproduction amplifier 6 via the reproduction changeover switch 5, and after being amplified by the reproduction amplifier 6, the reproduction signal is converted into data by the data demodulation circuit 7. The signal is converted into a signal, further converted into a digital audio interface format by the signal processing circuit 8, and outputted from the digital output terminal 9.

On the other hand, in the recording system, after a digital data signal input from a digital input terminal 10 is unformatted by a signal processing circuit 8, the data modulation circuit 1
1, the data signal is converted into a recording signal, amplified by a recording amplifier 12, sent to each magnetic head 2A, 2B via a recording changeover switch 13, and recorded on a magnetic tape 3 by each magnetic head 2A, 2bB. Ru.

Next, to explain the system speed control system, the rotating drum 1 is controlled by a servo circuit so that its drum motor (not shown) rotates in synchronization with the clock output from the basic clock control circuit 14.
5, the magnetic tape 3 is run at a constant speed by a capstan 16 whose capstan motor (not shown) is synchronized with the clock output from the basic clock control circuit 14. Servo circuit 15 to rotate
controlled by Basic clock control circuit 14
generates various clocks for controlling all systems, and the servo circuit 15
In addition, the signal is supplied to each block such as a data demodulation circuit 7, a data modulation circuit 11, and a signal processing circuit 8. As means for setting the clock frequency to the basic clock control circuit 14, there is a panel switch 17 for setting the clock frequency by external operation during playback;
A recording speed calculation circuit 18 is provided which calculates a clock frequency from an input digital data signal during recording. This recording speed calculation circuit 18 is
A transfer frequency detection section 18A detects the speed of the reproduction system from the input digital data signal, and a sampling frequency detection section 18A detects the sampling frequency from the digital audio interface format of the input digital data signal.
A, and a calculation unit 18C that calculates the system clock frequency based on the detection values of both detection units 18A and 18B.

Next, the operation of the above embodiment will be explained with reference to FIGS. 2 to 4. FIG. 2 shows a track pattern on a magnetic tape 3 recorded by a rotating drum 1 having two magnetic heads 2A and 2B, and as described above, the running speed of the magnetic tape 3 is
Since V _t is sufficiently slow compared to the rotational speed V _D of the rotating drum 1, the inclinations of tracks A and B are similar to those of the magnetic tape 3.
is the same as the inclination with respect to the rotating drum 1. In the figure, track A is recorded by one magnetic head 2A, and track B is recorded by the other magnetic head 2B. During playback, each track A, B is moved to the corresponding magnetic head 2.
A and 2B are accurately traced in the direction of the arrow. In this case, both magnetic heads 2A and 2B are traced alternately, and data recorded on each track A and B is picked up.

Assuming that double speed is set by the panel switch 17 when dubbing is performed, the basic clock control circuit 14 controls the clock frequency of the entire system to be twice that of normal operation. Then, the servo circuit 15 causes the magnetic tape 3 to
is 16.3mm/sec, which is double the 8.15mm/sec during normal operation.
At the same time, the rotating drum 1 is rotated at a rotation speed of 66.6 rps, which is twice the 33.3 rps during normal operation, and the data on the magnetic tape 3 is transferred by both magnetic heads 2A and 2B during normal operation. Against 2
Picked up twice as fast. Figure 3 a, b
2 shows the envelope waveform after the playback signal picked up by both magnetic heads 2A and 2B is amplified by the playback amplifier 6 via the playback changeover switch 5. FIG. Double-speed dubbing is shown, and A' and B' in the figure are reproduction signals picked up by one and the other magnetic heads 2A and 2B, respectively.

The reproduced signal thus amplified is demodulated and converted into a data signal by the data demodulation circuit 7 at the next stage, and then sent to the signal processing circuit 8. At this time, the data recorded on the magnetic tape 3 is, for example, 48K.
If it was sampled at Hz,
In normal operation, the signal is processed at a speed of 96 Kbyte/sec, whereas in the playback operation in this double speed dubbing, the signal is processed at a speed of 196 Kbyte/sec. The data thus prepared is converted by the signal processing circuit 8 into a digital audio interface format as shown in FIG. This format is from 1986.
It is a well-known specification decided at the DAT (Digital Audio Tape Recorder) conference, and B synchronization signal 1
9, M synchronization signal 20, W synchronization signal 21, preliminary data 22, audio data 23, validity flag 24, user data 25, channel data 26 and parity 27.

This digital audio interface formatted and output digital signal is input to an audio digital tape recorder on the recording side. In the transfer frequency detection section 18A, the transmission speed from the reproduction system, that is, the transfer frequency, is detected from the digital signal input from the digital input terminal 9. For example, while detecting B, M, and W synchronization signals 19, 20, and 21 in a digital audio interface format,
It is obtained by counting the synchronization signals 19, 20, 21 within seconds. As is clear from the explanation during the playback operation, a count value of 192000 is obtained and a transfer frequency of 192 Kbyte/sec is detected.

On the other hand, the input digital signal is also sent to a sampling frequency detection section 18B to detect the sampling frequency of the format. For example, channel data 26 to 48K in the above format.
Hz is detected. Then, in the calculating section 18C, a clock frequency is calculated based on each detection value of both the detecting sections 18A and 18B to make the recording system correspond to the reproducing system and vary the system speed to an appropriate system speed. In this embodiment, the following calculation is performed: 192 Kbyte/sec÷(48 KHz×2)=2. This calculation result is sent to the basic clock control circuit 14, and the basic clock control circuit 1
4 variably controls the system clock frequency of the servo circuit 15, data modulation circuit 11, signal processing circuit 8, recording changeover switch 13, etc. so that the frequency is twice that of normal operation, and the rotating drum 1 is operated at double speed.
While being rotated at 66.6 rps, the magnetic tape 3 is run at double speed of 19.3 mm/sec, and dubbing at double speed is performed without any problem.

It should be noted that the present invention is not limited only to the above-mentioned embodiments, and it goes without saying that various embodiments are possible without departing from the scope of the claims. For example, in the above embodiment, the sampling frequency is 48KHz.
Although we have explained double-speed dubbing, the same applies when the sampling frequency is 44.1KHz or 32KHz.
Needless to say, it is possible to perform double speed dubbing, and it is also possible to perform dubbing at speeds other than double speed, such as 1.2x or 1.8x dubbing.

<Effects of the Invention> Since the present invention is configured and operates as described above, according to the digital audio tape recorder of the present invention, the system clock of the playback system can be set by external operation and the data to be digitally output can be transferred. The configuration includes means for varying the speed, and means for detecting the transfer frequency and sampling frequency from the input data signal and calculating and setting the recording system clock frequency from the detection results, so stable operation is possible. Variable speed dubbing can be performed, and high speed dubbing such as double speed can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention.
Fig. 2 is an explanatory diagram of the track pattern recorded on the magnetic tape, Fig. 3 a and b are explanatory diagrams showing the relationship between the envelopes during normal operation and double speed dubbing, and Fig. 4 is an explanatory diagram of the track pattern recorded on the magnetic tape. FIG. 2 is an explanatory diagram of a surface format. 1...Rotating drum, 7...Data demodulation circuit, 8
... Signal processing circuit, 11 ... Data modulation circuit, 1
4... Basic clock control circuit, 15... Servo circuit, 16... Capstan, 17... Panel switch, 18... Recording speed calculation circuit, 18A... Transfer frequency detection section, 18B... Sampling frequency detection section, 18C ...Calculation section.

Claims (1)

[Claims] 1. A servo circuit that controls the rotational speed of the rotating drum and the capstan, a data demodulation circuit that converts a reproduction signal into a data signal, and a data modulation circuit that converts an input data signal into a recording signal.
A signal processing circuit that converts the data signal from the data demodulation circuit into a digital audio interface format during playback and unformats the input digital signal during recording, and detects the transfer speed and sampling frequency on the playback side from the input digital signal during recording. a recording speed calculation circuit that calculates a clock frequency from these detected values, and a servo circuit that corresponds to an external setting value during playback and an output value of the recording speed calculation circuit during recording, respectively.
A digital audio tape recorder comprising a basic clock control circuit that variably controls clock frequencies of a data demodulation circuit, a data modulation circuit, and a signal processing circuit.