JPS62239488A - Digital signal recording level supervising device - Google Patents

Abstract

PURPOSE:To execute the necessary measure such as the adjustment of a recording current by assuming a recording level from the envelope of a reproduced digital signal and generating the alarm of the deterioration of an over-writing characteristic. CONSTITUTION:A signal from other edge of a resistor 18 is stored into capacitors 22 and 23 through a switch 20, which is turned on during the pre or post ample period of a digital signal, and a switch 21 which is turned on during the data respectively, the stored signal is supplied to an arithmetic amplifier 24 and a difference component is removed. The signal of the difference component is supplied to a comparator 25, the difference component comes to be the prescribed size or above, and then, an alarm signal is outputted to an output terminal 26. The level difference of the envelope between the shortest wavelength part of the reproduced digital signal and the longest wavelength part is removed from the amplifier 24, and when the difference is increased to, for example, 2.5 times or above, the deterioration of the overwriting characteristic is judged and an alarm is generated. Thus, the measure such as the adjustment of the recording current is executed and the overwriting characteristic can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital (No. N) recording level monitoring device used in a digital signal recording/reproducing device or the like.

[Summary of the invention]

The present invention relates to a digital signal recording level monitoring device that issues an alarm when the +7 bell relationship between the envelopes of the shortest wavelength part and the longest wavelength part of a reproduced digital signal exceeds a predetermined range, thereby deteriorating override characteristics. This makes it possible to effectively prevent this.

(Prior art) In digital signal recording, an erasing end is generally not used.
The previous record ('i
The ff number is deleted. In this case, the recording current becomes large, and especially when low-frequency signals are recorded deep into the magnetic layer, when the next recording is made, if the same part of the recording is a pongee area signal, it will not be completely erased, and the erased signal will remain. This may cause interference with the signal during playback.

In other words, Figure 2 shows the reproduction output (
mV (corresponding to recording depth), and the characteristics shown in the figure are shown for each recording signal frequency (MHz). In this figure, the numbers for the second type shown on the horizontal axis are the upper stage when there is no wear on the gear wheel (gap depth is 60 μm), and the F stage when the gear tooth depth is 46 μm due to wear. Then, the recording current increases by about 43%.

Therefore, in this figure, the recording current is set to 5 when there is no wear.
If it is set to 0mA, then the playback output in the western 15MHz range is about 50mV, whereas the playback output in the low range 3-8M1lz is around Loomν.If the difference in recording level is about twice like this, it is an override characteristic. There is no problem.

However, if the gap depth wears down to 46 μm with the same recording current to 50 m, the playback output of 15MIIz at that time is about 45 mV, while the playback output of 3MHz, for example, is about three times that, nearly 140 mV. With this, sufficient erasing was not performed and the override characteristics deteriorated.

[Problem that the invention seeks to solve]

As described above, in the conventional technology, when the recording current remains constant and the head wears out, the recording level in the low range increases and the override characteristic deteriorates.

[Means for solving problems]

The present invention detects the envelopes of the shortest wavelength part (post-preamble) and the longest wavelength part (data) of the reproduced digital signal (operational amplifier (24)). This digital signal recording level monitoring device is characterized in that it issues an alarm (output terminal (26)) when the range (comparator (25)) is exceeded.

[Effect]

According to this, the recording level is estimated from the envelope of the reproduced digital signal (G), and an alarm is issued for the deterioration of the override characteristics. 16 can be performed.

〔Example〕

In FIG. 1, a digital signal recorded by a recording head (not shown) is reproduced by a so-called confirmation reproduction head, and this reproduced digital signal is supplied to an input terminal (1).

This input terminal (1) is the resistor B (2) ta+ (41
A bias [ifl I] is connected to the base of the pnp transistor (5) through the resistor; ).Furthermore, the collector of this transistor (5) is grounded through resistors (11) and (12), and the collector of is connected to one end of a capacitor (13). One end of the capacitor (13) is grounded through a series circuit of a resistor (14), a parallel circuit of a capacitor (15), and a coil (16).The other end of the capacitor (13) is connected to the resistor (18) through a diode (17). This resistor (■8) is connected to one end, and the other end of this resistor (■8) is a capacitor (
19). Note that the numbers in the figure indicate the values of the valley elements.

As a result, the envelope is detected, and the shortest wavelength part of the digital signal is extracted by determining the values of the capacitor (15) and the coil (16), and the shortest wavelength part of the digital signal is further connected to the resistor (kk) (12).
(14) etc. to apply desired peaking.

Generally, in digital signals, the shortest wavelength portion is provided in the so-called preamble or postamble portion, and the synchronization pattern in the data tray is formed with the RTK long wavelength.

Therefore, No. 14 from the other end of the above-mentioned resistor (18) is connected to the capacitor ( 22) (
23), and this stored signal is supplied to the operational amplifier (24) to extract the difference component.The signal of this difference component is then supplied to the comparator (25), and this difference ′?1 when the component becomes larger than the specified value
A notification signal is output to the output terminal (26).

Therefore, in this circuit, the amplifier (2=1) extracts the level difference of the envelope C1-wave between the shortest wavelength part and the longest wavelength part of the reproduced digital signal (g), and this difference is, for example, 2.5 times When the opening is more than
The envelope of the playback output corresponds to the recording depth of the signal, which corresponds to the recording level.

In this way, a warning of deterioration of the override characteristics is issued,
This makes it possible to take measures such as adjusting the C recording current and maintain the ζ override characteristic.

Note that the signal with the shortest wavelength in a digital signal has low energy, and cannot be detected at the same rate as the longest wavelength when detecting an envelope. For this reason, there is a possibility that the detection of the difference component may not be performed well, but according to the circuit described above, the energy is increased by applying a desired peaking to the shortest wavelength portion, and the detection is performed well. .

〔Effect of the invention〕

According to this invention, the recording level is estimated from the envelope of the reproduced digital No. 16, and an alarm is issued for the deterioration of the override characteristic. You can now type i61.

[Brief explanation of drawings]

1 is a diagram illustrating a configuration 1 of an example of the present invention, and FIG. 2 is a diagram for explaining a conventional technique. (1) is an input terminal, (21(31(41(61(71()
11) (12) (14) ([8] is) 1 (resistor, (5) is transistor, +81f9) (13) (+
5) (19) (22) (23) is a capacitor, (1o) is a power supply terminal, (16) is a coil, (17)
) is a diode, (24) is a v′A multiplier width amplifier 25)
is a comparator, and (26) is an output terminal.

Claims (1)

[Claims] The present invention detects the envelopes of the shortest wavelength portion and the longest wavelength portion of the reproduced digital signal, and issues an alarm when the level relationship of the detected envelopes exceeds a predetermined range. Features: Digital signal recording level monitoring device.