JPH0770154B2 - Digital recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a digital recording apparatus suitable for application to a digital audio tape recorder or the like adapted to convert an analog signal into a digital signal for recording.

[Prior Art] A digital recording device, such as a digital audio tape recorder (DAT), which converts an analog signal into a digital signal for recording, is well known. It doesn't matter. This is because in the case of a digital signal, the digital signal may be recorded as it is, and in the case of an analog signal, it may be converted into a digital signal and then recorded.

Therefore, in the case where an analog signal or a digital signal is output as the output signal, there is an advantage that the recording signal is less deteriorated when the recording is performed by using the digital signal.

However, as its input source, for example, a source such as a compact desk (CD), the standard requires that an analog signal be used for recording.

Thus, in order to record an analog signal, it is necessary to once convert it into a digital signal as described above.

[Problems to be Solved by the Invention] By the way, when an analog signal is once converted into a digital signal and then recorded as described above, the analog signal must be adjusted to an appropriate signal level and then converted into a digital signal. However, there is a problem that an analog signal having a dynamic range or more is digitized.

Conventionally, there is no particular means for adjusting the input level to an appropriate value. Therefore, it is the current situation that the setting is manually performed to an optimum level.
In this, there is no compensation converted to a digital signal at the optimum level.

In view of this, the present invention proposes a digital recording apparatus which solves the above-mentioned conventional problems with a simple structure and is capable of automatically setting the optimum level.

[Technical Means for Solving Problems] In order to solve the above-mentioned problems, in the present invention, in a digital recording device that converts an analog signal into a digital signal and records the level, the level with respect to an input analog signal. An adjusting means, an A / D converter that converts a level-adjusted analog signal into a digital signal, a digital signal output from this A / D converter, and an input digital signal having the same signal content as the input analog signal. And a digital comparator for level comparison, and by adjusting the level adjusting means by the comparison output of the digital comparator, the level of the input analog signal is automatically adjusted to the optimum level. It is a thing.

[Operation] In this configuration, the analog signal supplied from the analog source is converted into the digital signal Sa. The original analog signal converted into the digital signal Sa is a signal whose level is adjusted by the level adjusting means.

This digital signal Sa is supplied to the digital comparator.

On the other hand, the same signal content as the input analog signal is supplied from the digital source in the form of the digital signal Sd, which is supplied to the digital comparator.

Both levels are compared by this digital comparator. The signal to be compared is the reference signal included in the digital signal.

The level adjusting means is controlled by its comparison output so that the level of the digital signal Sa from the analog source coincides with the level of the reference signal from the digital source.

Here, it is assumed that the level of the reference signal is adjusted in advance to the optimum recording level.

[Embodiment] Subsequently, an example of a digital recording apparatus according to the present invention will be described in detail with reference to the drawings in the case of being applied to the DAT described above.

In the figure, reference numeral 10 is a systematic diagram of the main part of the DAT according to the present invention. Reference numeral 30 indicates a CD as an example of an input source source.

In the DAT 10, 11 indicates an analog signal input terminal, 12 indicates a digital signal input terminal, and the analog signal input to the terminal 11 is adjusted to an optimum level for recording by a level adjusting means (volume, etc.) 13. Later, A / D
It is converted into a digital signal Sa by the converter 14.

The digital signal Sa is supplied to the digital signal processing circuit 15 of the next stage via the switching circuit 40 to be converted into a predetermined signal format, and then supplied to the rotary magnetic head device 17 via the high frequency amplifier 16 for recording.

Similarly, the digital signal Sd supplied to the terminal 12 is supplied to the digital interface 25, the switching circuit 40, and the digital signal processing circuit 15 to perform the same format processing as described above, and then the high frequency amplifier 16 to rotate the magnetic field. It is recorded by the head device 17.

The above-mentioned switching circuit 40 is for selectively switching the digital signal Sd or the digital signal Sa. To give an example of the switching operation, an output signal such as a compact disc (CD) is used as an input source. As an analog signal as well, there is one that is designed to be output as a digital signal, but if the standard requires recording using an analog signal, the switching circuit 40 outputs the digital signal Sa. The switching operation is performed so as to be selected. In the present invention, in addition to such a configuration, a digital comparator 26 is provided on the terminal 12 side via the digital interface 25,
The digital signal Sd input to the terminal 12 is supplied as it is for the reference level, and the digital signal Sa whose level is adjusted by the level adjusting means 13 is also supplied.

The level adjusting means 13 is automatically adjusted by the comparison output.

On the other hand, 30 shows an example of an input source source. This example illustrates a CD. Reference numeral 31 denotes a CD main body, and an analog signal is output from one output terminal 32, and a signal having the same content as the analog signal is digitized and output from the other output terminal 33.

The CD main body 31 is provided with a reference signal source for level adjustment. In the embodiment, in addition to the test desk 35,
A test signal generator 36 and a conventional music desk 37 are provided.

Since a single reference signal source may be used, it is not necessary to prepare a plurality of reference signal sources as in the embodiment.

Now, in this configuration, when a CD is used as an input source source, since a digital signal is output at the same time as an analog signal, this digital signal is used as a reference signal for level adjustment.

For example, the test desk 35 is loaded and the test desk 35 is reproduced. At that time, an analog signal and a digital signal are obtained at the terminals 11 and 12, respectively. The analog signal is A / D with the level adjusted appropriately by the level adjusting means 13.
To be converted.

On the other hand, the digital signal Sd supplied via the digital interface 25 is the signal level itself reproduced from the test desk 35.

Here, it is assumed that the level of the reference digital signal reproduced from the test desk 35 has been adjusted in advance to a level that provides the optimum recording level.

In the level adjusting means 13, the digital signal Sd serving as the reference signal
On the other hand, when the level of the input digital signal Sa is digitally compared and the level of the input digital signal Sa does not match the level of the reference digital signal Sd, the level adjusting means 13 is automatically adjusted by the comparison output. .

When the level adjusting means 13 is adjusted, the digital level of the input digital signal Sa changes and this changes again to the reference digital signal.
Level compared to Sd.

Such a control mode is executed until the level of the input digital signal Sa matches the level of the reference digital signal Sd, and when they match, the level adjusting means 13 is fixed in the adjusted state.

As a result, the input analog signal is digitized at the optimum level and recorded.

A test signal generator 36 may be used as the reference signal source.

Also, when using a general music desk 37, the music signal is directly compared by the digital comparator 26 and the level is adjusted by passing through a circuit that corrects the deviation of the time axis of the input analog signal and the input digital signal. Can also be executed.

As described above, according to the configuration of the present invention, the digital comparator outputs the digital signal output from the A / D converter and the input digital signal having the same signal content as the input analog signal. The levels are compared by means of, and the level adjusting means is controlled by the comparison output.

According to this, since the level of the input analog signal can be automatically adjusted to the optimum level, the analog signal exceeding the dynamic range is A / D converted or digitized in a state outside the optimum level. There is a practical benefit that can reliably eliminate such drawbacks.

Therefore, the digital recording apparatus according to the present invention is extremely suitable when applied to the above-mentioned DAT or the like.

[Brief description of drawings]

FIG. 1 is a system diagram of a main part showing an example of a digital recording device according to the present invention. 10 …… DAT 11 …… Analog signal input terminal 12 …… Digital signal input terminal 13 …… Level adjusting means 14 …… A / D converter 15 …… Digital signal processing circuit 17 …… Rotary magnetic head device 26 …… Digital Comparator 30 …… CD

Claims (3)

[Claims] 1. A digital recording device for converting an analog signal into a digital signal for recording and a level adjusting means for an input analog signal, and an A / D converter for converting the level-adjusted analog signal into a digital signal. And a digital comparator for level-comparing the digital signal output from the A / D converter with an input digital signal having the same signal content as the input analog signal, and the comparison output of the digital comparator A digital recording apparatus characterized in that the level of the input analog signal is automatically adjusted to an optimum level by adjusting the level adjusting means according to. 2. The digital recording apparatus according to claim 1, wherein a signal from a test desk is used as the input analog signal and the input digital signal. 3. The digital recording apparatus according to claim 1, wherein a signal from a test signal generator is used as the input analog signal and the input digital signal.