JPH0682492B2 - Digital data reproduction equalizer adjustment device - Google Patents

Description

The present invention relates to a digital data reproduction equalizer adjustment device of a recording / reproduction device for recording digital data such as a digital audio signal on a magnetic tape or the like.

[Outline of Invention]

The present invention is a digital data reproduction equalizer adjustment device of a recording / reproduction device for recording digital data such as a digital audio signal on a magnetic tape or the like, in which a preamble signal and a postamble signal are arranged before and after a block of digital data. A recording medium to be recorded, a reproduction equalizer for processing a signal reproduced from the recording medium, a detection means for envelope-detecting the output of the reproduction equalizer, and a detection output of the detection means for sampling at a first timing. The first sampling means, the second sampling means for sampling the detection output of the detection means at the second timing, the comparison means for comparing the levels sampled by the first and second sampling means, and the comparison means And means for displaying the level difference detected by the comparison of As a signal of at least one of a preamble signal and a postamble signal recorded on the body, the front part is a first continuous signal having a wavelength equal to the longest wavelength of the digital data, and the rear part is a shortest wavelength of the digital data. A first continuous signal having an equal wavelength and sampled by the first sampling means
Is the timing at which the first continuous signal is reproduced, and the second timing sampled by the second sampling means is the timing at which the second continuous signal is reproduced. By adjusting the reproduction equalizer so that the difference becomes a predetermined value, the reproduction equalizer characteristic can be adjusted easily and accurately.

[Conventional technology]

Conventionally, as a recording / reproducing apparatus for recording digital data such as a digital audio signal on a magnetic tape, there is, for example, a rotary head type. In the case of this rotary head system, recording is performed by providing a digital data recording track inclined with respect to the running direction of the magnetic tape. FIG. 5 is a diagram showing an example of a recording format of a recording / reproducing apparatus of this type. This example is a digitized audio signal of a video tape recorder. A video track (1a) inclined with respect to the traveling direction) is formed and sequentially recorded by the rotary head, and a digital audio track (1a) is recorded below the video track (1a).
b) is formed and sequentially recorded by the rotating head. As a track for recording / reproducing with a fixed head, a first analog audio track (1c) and a second analog audio track (1d) are provided above the video track (1a), and the video track (1a) and the digital audio track (1a). Control track between (1b) and (1e)
However, the third analog audio track (1f) is formed below the digital audio track (1b).

Of the tracks formed in this way, each one of the digital audio tracks (1b), that is, one field recording format is constructed as shown in FIG. 6, for example. This recording format is from the beginning,
Preample signal (3a) 280 bits, sync signal (3b)
8 bits, block address signal (3c) 8 bits,
The CRCC (cyclic code) signal (3d) is composed of 8 bits and the data signal (3e) is composed of 256 bits.
b), block address signal (3c), CRCC signal (3d) and data signal (3e) are repeated, and the data signal (3e) is set to 0.
It is composed of 88 times from ~ 87. And the last data signal (3
After e), the sync signal (3b) is composed of 8 bits, and finally the postamble signal (3f) is composed of 272 bits.

Here, the preamble signal (3a) and the postamble signal (3f) are composed of continuous repetitive waveforms of the shortest wavelength of the recorded data signal (3e), as shown in FIG.
For example, a continuous repeating waveform of 16MHz (32M bits),
Since the preamble signal (3a) and the postamble signal (3f) are located at the beginning and the end of one field, there are advantages such as a good connection between the fields.

[Problems to be solved by the invention]

By the way, when digital data is reproduced by the recording / reproducing apparatus as described above, it is necessary to properly adjust the reproduction equalizer. The adjustment of the reproduction equalizer is performed by using an oscilloscope to observe the reproduction waveform as shown in FIG. 8, so-called eye pattern, so that the horizontal and vertical aperture widths a and b of the eye pattern are maximized. The adjustment is performed by setting. However, since this eye pattern has a waveform that is difficult to identify,
There are differences in the degree of adjustment depending on the adjuster, and it is not always necessary to make good adjustments. Further, since an oscilloscope is required, it is difficult for the user of the recording / reproducing apparatus to easily adjust the reproduction equalizer.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a reproduction equalizer adjusting device for digital data, which can easily perform accurate adjustment of the reproduction equalizer.

[Means for solving problems]

The digital data reproduction equalizer device of the present invention comprises a recording medium (8) in which a block of digital data is recorded with a preamble signal and a postamble signal before and after the block, as shown in FIGS. 1 and 2, for example. A reproduction equalizer (11) for processing a signal reproduced from the recording medium (8), a detection means (13) for envelope-detecting the output of the reproduction equalizer (11), and a detection output of the detection means (13). First sampling means (14) for sampling at a first timing, second sampling means (15) for sampling the detection output of the detecting means (13) at a second timing, and first and second sampling Comparing means (16) for comparing the levels sampled by means (13) and (15) and display of the level difference detected by the comparison by this comparing means (16) Means (17) for recording at least one of the preamble signal (3a) and the postamble signal (3g) recorded on the recording medium (18), and the front part is set to the longest wavelength of the digital data (3e). The first continuous signal (3h) having the same wavelength, and the second portion having the wavelength equal to the shortest wavelength of the digital data (3e) at the rear.
Continuous signal (3i) of the first sampling means (14)
The first timing sampled by is the timing at which the first continuous signal (3h) is reproduced, and the second timing sampled by the second sampling means (15) is the second continuous signal (3i). The timing to be played,
The reproduction equalizer (11) is adjusted so that the level difference displayed by the display means (17) becomes a predetermined value.

[Work]

The digital data reproduction equalizer adjustment device of the present invention is
Preamble signal (3a) or postamble signal (3g)
Of at least one of the amble signals of (3h) is a continuous signal having a wavelength equal to the longest wavelength of digital data,
By making the rear part (3i) a continuous signal of a wavelength equal to the shortest wavelength of digital data, and adjusting the reproduction equalizer so that the reproduction output level of the front part (3h) and the rear part (3i) of this amble signal becomes a predetermined value. , You can easily adjust the good playback equalizer.

〔Example〕

An embodiment of the digital data reproduction equalizer adjusting apparatus of the present invention will be described below with reference to FIGS.
1 to 4, parts corresponding to those in FIGS. 5 to 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

The reproducing / equalizing device for reproducing digital data according to this embodiment is applied to a recording / reproducing device for digitizing and recording an audio signal of a video tape recorder as in the case of FIG. FIG. 2 is a diagram showing a recording signal of one field of a recording track of a digital audio signal of the recording / reproducing apparatus. A preamble signal (3a) is a data signal (3e) recorded in the same manner as in the example of FIG. It consists of a continuous repeating waveform with the shortest wavelength of. The postamble signal (3g) is composed of a continuous repeating waveform of the longest wavelength of the data signal (3e) in which the front part (3h) of the two parts divided into the front part (3h) and the rear part (3i) is recorded. , The rear part (3i) is recorded and consists of a continuous repeating waveform of the shortest wavelength of the data signal (3e). The longest wavelength and the shortest wavelength of this data signal (3e) are determined by the recording method of the data signal (3e). For example, the longest wavelength is 4 MHz (8 bits) and the shortest wavelength is 16 MHz (32 M bits). The preamble signal (3
a) and the postamble signal (3g) are arranged at the beginning and end of one field of the recording format shown in FIG.

Next, the adjustment of the reproduction equalizer of this recording / reproducing apparatus, in which each field for recording digital data in this way is described.

Conventionally, the adjustment of the reproduction equalizer is performed by observing the eye pattern of the reproduction waveform with an oscilloscope as shown in FIG.
Although the opening widths a and b of the eye pattern are maximized, the reproduction level of the longest wavelength portion and the reproduction level of the shortest wavelength portion of the recorded data when the opening widths a and b of the eye pattern are maximized. It is known that the ratio between and is always approximately constant. FIG. 3 is a diagram showing this reproduction level, showing the reproduction level Va of the longest wavelength part x (for example 4 MHz) and the shortest wavelength part y (for example 16 MHz) when the eye pattern aperture widths a and b are maximum. The ratio Vb / Va to the reproduction level Vb is always substantially constant. Therefore, to obtain this ratio Vb / Va,
For example, by selecting and adjusting an appropriate reproduction equalizer characteristic from the reproduction equalizer characteristics shown by the curves in FIG. 4, the optimum reproduction equalizer characteristic is obtained. Here, as described above, in this example, the front part (3h) of the postamble signal (3g) consists of the continuous repetitive waveform of the longest wavelength of the recording data, and the rear part (3h).
Since i) consists of the continuous repetitive waveform of the shortest wavelength of the recorded data, the front part (3h) and the rear part (3i) of this postamble signal (3g) are reproduced, the reproduction levels are compared, and the ratio
By adjusting the reproduction equalizer characteristic so as to be Vb / Va, the optimum reproduction equalizer characteristic is obtained.

FIG. 1 is a diagram showing a reproduction equalizer adjusting circuit for adjusting the reproduction equalizer characteristic in this way.
(8) is a magnetic tape in which digital data is recorded in advance as described above, and a digital audio signal reproducing head (9) is arranged on a rotating drum (not shown). The output signal of the reproducing head (9) is supplied to the amplifier (10), and the signal reproduced by the reproducing head (9) is amplified. The output signal of the amplifier (10) is supplied to the RF equalizer (11), and the reproduction equalizer characteristic is adjusted by the RF equalizer (11). The output signal of the RF equalizer (11) is supplied to the reproduction signal output terminal (12) and the RF envelope detector (13), and the reproduction signal whose reproduction equalizer characteristic is adjusted is reproduced from the reproduction signal output terminal (12) in the reproduction circuit system ( (Not shown), and the reproduction signal is envelope-detected by the RF envelope detector (13). The output signal of the RF envelope detector (13) is supplied to the first and second sample and hold circuits (14) and (15), and the postamble signal (3g ) Is sample-held, and the second sample-hold circuit (15) samples and holds the rear part (3i) of the postamble signal (3g) in the reproduced signal. The output signals of the first and second sample and hold circuits (14) and (15) are supplied to the first and second input terminals of the level comparator (16), respectively, and the postamble signal is supplied by the level comparator (16). The output levels of the front part (3h) and the rear part (3i) of (3g) are compared, and the ratio of the reproduction level is detected by this comparison. Then, a detection signal corresponding to the detection ratio is supplied to the meter (17), and the meter (17) displays the output level difference between the front part (3h) and the rear part (3i) of the postamble signal (3g). By doing so, the reproduction equalizer characteristic is adjusted by the RF equalizer (11) while observing the display on the meter (17) so that the display on the meter (17) becomes the ratio at the optimum reproduction equalizer characteristic described above. To do. In this way, the reproduction equalizer characteristic can be adjusted well. In addition,
The continuous repetitive waveform of the shortest wavelength has a preamble signal (3) instead of the rear part (3i) of the postamble signal (3g).
It can also be obtained from a).

As described above, the postamble signal (3
Adjust the playback equalizer by setting the front part (3h) of g) as the longest continuous wavelength repetitive waveform of the recorded data (3e) and the rear part (3i) as the shortest continuous wavelength repeated waveform of the recorded data (3e). Sometimes, by adjusting the reproduction equalizer characteristics so that the output level difference between the front (3h) and the rear (3i) of the postamble signal (3g) becomes a predetermined ratio, the optimum reproduction equalizer characteristics are obtained, and the oscilloscope etc. It's easy to use, and it's not difficult to judge like when you look at a waveform with an oscilloscope.
There is no variation in adjustment, and accurate adjustment can be made reliably.

In the above-mentioned embodiment, the adjustment device is one in which the wavelengths of the front part (3h) and the rear part (3i) of the postamble signal (3g) are changed, but the front and rear parts of the preamble signal (3a) are used. It can also be used to adjust the equalizer by changing the wavelength. Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

〔The invention's effect〕

As described above, according to the digital data reproduction equalizer adjustment device of the present invention, the front portion (3h) and the rear portion (3i) of the postamble signal (3g) or the front portion and the rear portion of the preamble signal (3a) are By arranging the continuous repetitive waveform of the wavelength equal to the longest wavelength and the wavelength equal to the shortest wavelength of the digital data signal (3e) respectively, there is an advantage that the reproduction equalizer characteristics can be adjusted easily and accurately. .

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a digital data reproduction equalizer adjusting apparatus of the present invention, FIGS. 2 to 4 are diagrams for explaining one embodiment of the present invention, and FIGS. FIG. 7 is a diagram for explaining a digital data recording / reproducing apparatus, and FIG. 8 is a diagram for explaining a conventional reproducing equalizer adjusting apparatus. (3a) is the preamble signal, (3e) is the digital audio data signal, (3g) is the postamble signal, (3h) is the front part of the postamble signal, (3i) is the rear part of the postamble signal, and (11) is RF. It is an equalizer.

Claims (1)

[Claims] 1. A recording medium in which a preamble signal and a postamble signal are recorded before and after a block of digital data, a reproduction equalizer for processing a signal reproduced from the recording medium, and an output of the reproduction equalizer. Envelope detecting means, first sampling means for sampling the detection output of the detecting means at a first timing, second sampling means for sampling the detecting output of the detecting means at a second timing, The preamble signal and the post recorded on the recording medium are provided with a comparing means for comparing the levels sampled by the first and second sampling means, and a displaying means for the level difference detected by the comparison by the comparing means. As a signal of at least one of the amble signals, the front part of the digital data A first continuous signal having a wavelength equal to a long wavelength, a rear portion and a second continuous signal having a wavelength equal to the shortest wavelength of said digital data, a first sampled at said first sampling means
Is set to the timing at which the first continuous signal is reproduced, and the second timing sampled by the second sampling means is set to the timing at which the second continuous signal is reproduced. A reproducing equalizer adjusting device for digital data, characterized in that the reproducing equalizer is adjusted so that the level difference becomes a predetermined value.