JPH03181063A - Digital audio tape recorder - Google Patents

Abstract

PURPOSE:To copy a subcode even when the copy is inhibited by modulating not only an audio signal but the subcode outside an analog audio signal band, frequency-multiplexing it over the analog audio signal and outputting this through an analog audio interface. CONSTITUTION:In a reproducing side DAT, a subcode data is modulated outside the frequency band of the analog audio signal by a subcode modulator 28, and the modulated subcode signal generated by the modulator 28 is frequency- multiplexed upon the regenerated analog audio signal by a frequency multiplexer 33. Then, in a recording side DAT, the multiplexed analog audio signal is separated by a low pass filter 16 and a band pass filter 34 into the analog audio signal and the modulated subcode signal, and the modulated subcode signal is demodulated into the subcode data by a subcode demodulator 36. By this method, in the case of the copy through the analog audio interface between two sets of DATs, the subcode is copied as well as the audio signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a digital audio tape recorder that copies the contents of a magnetic recording tape using an analog audio interface cable.

(Conventional technology) In recent years, digital audio tape recorders (hereinafter referred to as DAT
CDs (compact desk players) are becoming popular in the market because they have better sound quality than CDs (compact desk players), can record and playback, and can also record information other than audio.

With conventional DATs, when an audio signal is copied between two DATs, the playback DAT converts the main signal (digital audio data) and sub-signal (subcode data) into digital audio signals specified by the digital audio interface standard. The DAT on the recording side receives the sent digital audio signal, demodulates it into digital audio data and subcode data, processes it in a signal processing circuit, and copies it onto a magnetic recording tape. Furthermore, when copying a magnetic recording tape on which a digital copy prohibition code has been sung, copying by a digital audio interface is prohibited, so only digital audio data can be converted into an analog audio signal and copied by an analog audio interface. The conventional DAT will be explained below.

Fig. 3 is a block diagram showing the output section and input section of two conventional DATs. Fig. 3(a) shows the playback side DAT output section, and Fig. 3(b) shows the recording side DAT input section. show. In FIG. 3, 1 is a recording medium such as a magnetic tape, 2 is a playback head that reads the signal recorded on the magnetic tape 1, and 3 is a playback head that separates digital audio data and digital subcode data for the playback signal. For recording signals, digital subcode data is added to digital audio data, error correction code encoding/decoding, interleaving/
This is a signal processing circuit that performs processing such as deinterleaving. 4 is a digital audio data line on the playback side, 5 is a subcode (start ID, skip ID, time code, etc.) data line on the playback side, and 6 is a converter for converting the digital audio data output from the signal processing circuit 3 into an analog audio signal. 7 is a low-pass filter for removing unnecessary harmonic components of the analog audio signal; 8 is a digital-to-analog converter for converting the digital audio data and subcode data output from the signal processing circuit 3 into digital audio according to the digital audio interface standard; This is a digital audio interface encoder circuit that converts the format of the signal. 10
11 is an analog audio signal output terminal, 11 is a digital audio signal output terminal, 12 is an analog interface cable that transfers an analog audio signal, 13 is a digital interface cable that transfers a digital audio signal, 14 is an analog audio signal input terminal, and 15 is a digital audio signal terminal; 16 is a low-pass filter for preventing aliasing noise; 1;
7 is an analog-to-digital converter that converts the analog audio signal output from the low-pass filter 16 into digital audio data. A digital audio interface decoder circuit 19 demodulates an input digital audio signal into digital audio data and digital subcode data in accordance with the digital audio interface standard. 2o is a recording-side digital audio data line converted by the analog-to-digital converter 17; 21 is a recording-side digital audio data line decoded by the digital audio interface decoder circuit 19; and 22 is a recording-side digital audio data line decoded by the digital audio interface decoder 19. This is the subcode data line on the recording side. The system according to 6, 7, 10° 12, 14, 16, and 17 above is called an analog audio interface, and the system according to 8, 1 above is called an analog audio interface.
1.13.15.19 is called a digital audio interface. A digital/analog selection key 23 selects either copying using an analog audio interface or copying using a digital audio interface, and switches the signal line in conjunction with the digital/analog changeover switch 24. FIG. 3 shows that an analog audio interface is selected. 25 is a signal processing circuit that converts digital audio data and subcode data into a recording format specified by the DAT conference, and 26 is a signal processing circuit that records the signals generated by the signal processing circuit 25 on a magnetic recording tape 27.
This is a recording head that In the DAT configured as described above, when copying between two DATs, there are two types of copying: one using an analog audio interface and the other using a digital audio interface.

Next, the above conventional operation will be explained. In the case of a copy system using an analog audio signal, the playback side DAT output section (Fig. 3 (a)) converts the digital audio data obtained by the signal processing circuit 3 into an analog audio signal using the digital-to-analog converter 6, and converts the digital audio data into an analog audio signal. The analog audio signal is output from the audio signal output terminal 10, and the recording side DAT input section (Fig. 3(b)) inputs the sent analog audio signal from the analog audio signal input terminal 14, and outputs the analog audio signal from the analog audio signal input terminal 14.
In this system, an analog audio signal is converted into digital audio data by a digital converter 17, and processed and copied by a signal processing circuit 25. Next, in the case of copying using a digital audio interface, the playback side DAT
converts the digital audio data and subcode data obtained by the signal processing circuit 3 into a digital audio signal according to the digital audio interface format by the digital audio interface encoder circuit 8, and outputs it from the digital audio signal output terminal 11;
The recording side DAT inputs the digital audio signal sent from the digital audio signal input terminal 15, separates the digital audio signal into digital audio data and subcode data by the digital audio interface decoder circuit 19, processes the digital audio signal by the signal processing circuit 25, and copies the data. It is a system that does Copying using a digital audio interface does not convert the digital tD signal to an analog signal, so there is no signal deterioration, and subcode (
Start ID, skip ID, time code, etc.) can also be dubbed.

(Problem to be Solved by the Invention) In the conventional configuration as described above, it is impossible to copy a digital source with a copy prohibition flag added to protect music authors using a digital audio interface without quality deterioration. , it will rely on copying using an analog interface. However, copying using an analog audio interface has the problem that only the analog audio signal can be copied, and subcodes cannot be copied.

SUMMARY OF THE INVENTION The present invention solves the above problems and aims to provide a digital audio tape recorder that can copy subcodes using an analog audio interface even when copying using a digital audio interface is prohibited.

(Means for Solving the Problems) In order to achieve the above object of the present invention, a digital audio tape recorder records DAT on the tape at the playback side DAT.
A signal recorded according to the AT format is separated into digital audio data and subcode data by a signal processing circuit, the digital audio data is converted to an analog audio signal by a digital-to-analog converter, and the subcode data is converted into the frequency band of the analog audio signal. It has a configuration that includes a modulator that converts into a modulated subcode signal externally, and a multiplexer that frequency multiplexes the analog audio signal and modulated subcode data, and outputs the multiplexed signal output from the multiplexer through an analog interface cable, The recording side DAT has a filter that separates the multiplexed signal input through the analog interface cable into an analog audio signal and a modulated subcode signal, an analog-to-digital converter that converts the analog audio signal into digital audio data, and a modulating subcode signal. The apparatus includes a demodulator that demodulates subcode data into subcode data, and has a configuration in which digital audio data and digital subcode data are input to a signal processing circuit and recorded on a tape according to the DAT format.

(Function) With the above-described configuration, the present invention converts conventional digital audio data into an analog audio signal and converts the conventional digital audio data into an analog audio signal when copying a tape on which a flag for prohibiting copying through a digital audio interface has been added. However, with this configuration, when copying a tape with a copy prohibition flag added, not only the audio signal but also the subcode (start ID) is copied.

Skip ID, time code, etc.) is modulated outside the analog audio signal band, frequency-multiplexed onto the analog audio signal, separated by a filter on the copy side, and demodulated the modulated sub-code, allowing it to pass through only the analog audio interface. It becomes possible to copy both the audio signal and the subcode.

(Example) The present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a digital audio tape recorder according to an embodiment of the present invention. Hereinafter, unexplained symbols refer to the same parts as in the conventional example shown in FIG. 3.
is a reproduction-side DAT output section, which separates the signal reproduced from the magnetic tape 1 into an analog audio signal and a digital audio signal, and outputs the analog audio signal from the analog audio output terminal 10 and the digital audio signal from the digital audio output terminal ll. . Figure 1(b)
is the recording side DAT input section, and the analog audio signal input from the outside is input from the analog audio input terminal 14.
A digital audio signal is input from the digital audio input terminal 15 and DA is transferred to the magnetic tape 27 through internal processing.
Record according to T format. 3 performs processing such as 8-IO demodulation, error correction, and deinterleaving on the reproduced signal from the magnetic tape 1, and outputs digital audio data to signal line 4 and digital subcode data to signal line 5. This is a signal processing circuit that performs 28 is a modulator that modulates the subcode data output from the signal processing circuit 3 to the signal line 5 outside the frequency band of the analog audio signal and outputs a modulated subcode signal; 29 generates a carrier wave modulated by the subcode data; 30 is a bandpass filter for limiting the frequency band of the modulated subcode signal; 31 is a multiplex switch; 3
A subcode multiplexing key 2 is used to select whether or not to multiplex a modulated subcode signal onto an analog audio signal, and is linked to the multiplexing switch 31. 33 is a frequency multiplexer that multiplexes the analog audio signal output from the low-pass filter 7 and the modulated subcode signal output from the band-pass filter 30 without interfering with each other, as shown in FIG. FIG. 2 shows the spectrum of the multiplexed analog audio signal output from the frequency multiplexer 33. 38 in FIG. 2 is the spectrum of the analog audio signal, and 40 is the spectrum of the modulated subcode signal. Subcode modulator 28. The bandpass filter 30 modulates and filters the modulated subcode signal such that the lowest frequency f2 of the modulated subcode signal is higher than the highest frequency f2 of the analog audio signal. In FIG. 1, the multiplex switch 31 is closed and subcodes can be multiplexed. 34 is a bandpass filter that extracts the modulated subcode signal from the multiplex analog audio signal input from the analog audio input terminal 14;
5 is a carrier wave regenerator that regenerates a carrier wave from the modulated subcode signal, and 36 is a subcode salt WRW that demodulates the modulated subcode signal into subcode data using the carrier wave regenerated by the carrier wave regenerator 35. 37 is a subcode data line demodulated by the subcode demodulator 36, and 25 is an error correction code for the digital audio data output from the analog-to-digital converter 17 and the subcode data output from the subcode demodulator 36. addition of.

This is a signal processing circuit that performs interleaving and 5-tO modulation processing to convert the DAT conference into a specified format.

Next, the operation of the digital audio chip recorder in the embodiment configured as above will be explained.

When copying a tape that is prohibited from being copied using a digital audio interface between two DATs, it must be copied using an analog audio interface. In this case, the operation of copying subcodes at the same time will be explained. The digital audio data reproduced by the signal processing circuit 3 of the reproduction side DAT is input to the digital-to-analog converter 6. The subcode data reproduced at the same time is input to the subcode modulator 28. Digital audio data input to the digital-to-analog converter is converted into an analog audio signal, passes through a low-pass filter 7 that removes unnecessary harmonic components, and is input to a frequency multiplexer 33. Subcode modulator 28
The subcode data input to the subcode modulates a carrier wave generated by a carrier wave generator 29 and is output as a modulated subcode signal. The frequency band of the modulated subcode signal output from the subcode modulator is limited by a bandpass filter 30 so as not to interfere with the analog audio signal, and the modulated subcode signal is input to a frequency multiplexer 33. The output of the frequency multiplexer 33 is a multiplexed analog audio signal having the spectrum shown in FIG. 2, and is outputted from the analog output terminal IO to the analog interface cable 12. A multiplex analog audio signal transferred by an analog interface cable is input from an analog input terminal 14 of the recording side DAT and is separated into modulated subcode signals of the analog audio signal by a low pass filter 16 and a band pass filter 34. Analog audio signals are analog
It is input to the digital converter 17, converted into digital audio data, and subjected to signal processing j1! It is input to the circuit 25.

The modulated subcode signal is input to a carrier wave regenerator 35 and the carrier wave is regenerated. The modulated subcode signal is input to the subcode demodulator 36, demodulated into subcode data by synchronous detection using the recovered carrier wave from the carrier wave regenerator 35, and input to the signal processing circuit 25. The signal processing circuit 25 processes the input digital audio data and subcode data by adding an error correction code, interleaving, and 8-10 modulation, and outputs the data to a recording head 26 to be recorded on a magnetic recording tape 27.

As described above, according to this embodiment, the playback deck is provided with a subcode modulator, a bandpass filter, and a frequency multiplexer for multiplexing subcode data onto an analog audio signal, and the recording deck is provided with a modulation subcode modulator, a bandpass filter, and a frequency multiplexer. By providing a bandpass filter and subcode demodulator for obtaining an analog audio signal and subcode data from an analog audio signal multiplexed with code signals, it is possible to copy subcode data using analog dubbing using an analog audio interface. Can be done at the same time.

(Effects of the Invention) As described above, according to the present invention, a modulator that modulates subcode data outside the frequency band of an analog audio signal and a modulated subcode signal generated by the modulator are reproduced in the playback DAT. A multiplexer is provided to frequency-multiplex the analog audio signal, and the recording side DAT
By providing a filter that separates a multiplexed analog audio signal into an analog audio signal and a modulated subcode signal, and a demodulation circuit that demodulates the modulated subcode signal into subcode data, copies can be made between two DATs through an analog audio interface. If you want, the subcode can also be copied at the same time as the audio signal,
It has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a digital audio tape recorder according to an embodiment of the present invention, FIG. 2 is a spectrum diagram of a multiple analog audio signal of the present invention, and FIG. 3 is a block diagram of a conventional digital audio tape recorder. 1.27...Magnetic recording tape, 2...Reproduction head, 3,25...Signal processing circuit, 6...D/A
Converter, 7, 16...LPF, 8...Digital audio interface encoder circuit, 17...
A/D converter, 19... Digital audio interface decoder circuit, 23... Digital/analog selection key 24... Digital/analog changeover switch, 26... Recording head. 28... Subcode modulator, 29... Carrier wave generator, 30.34... BPF, 31... Multiplex switch,
32... Subcode multiplex key 33... Frequency multiplexer, 35... Carrier wave regenerator, 36... Subcode demodulator, 38... Analog audio signal, 39... Carrier wave. 40... Modulation subcode signal.

Claims (2)

[Claims] (1) A signal processing circuit that outputs digital audio data and subcode data, a digital-to-analog conversion circuit that converts the digital audio data into an analog audio signal, and a signal processing circuit that converts the subcode data into an analog audio signal. A digital audio tape recorder comprising: a modulator that performs modulation to generate a modulated subcode signal; and a multiplexer that frequency multiplexes the modulated subcode signal onto the analog audio signal. (2) a filter that divides a modulated subcode signal frequency-multiplexed into an analog audio signal into an analog audio signal and a modulated subcode signal; an analog-to-digital conversion circuit that converts the analog audio signal into digital audio data; and the modulator. The digital audio tape recorder according to claim 1, further comprising a demodulator that demodulates a subcode signal into subcode data, and a signal processing circuit that adds the digital subcode data to the digital audio data. .