JPS6055904B2 - Automatic gain adjustment processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an automatic gain adjustment processing method, in particular, a method in which the signal level after amplifying the signal read from the head within the ARA area provided at the leading edge of the magnetic tape is set to a predetermined level. When the predetermined level is not reached, the predetermined level is lowered, and the gain of the level adjustment amplifier is readjusted in order to make the level of the signal read from the head reach the lowered level based on the lowered level. The present invention relates to an automatic gain adjustment processing method.

GCR (Group Co., Ltd.) in conventional magnetic tape devices
deRecording) mode, ARA(
When adjusting the gain of the level adjusting amplifier in the Amplitude Reference Area) area, the gain of the level adjusting amplifier is increased stepwise at a certain period after the gain adjustment is started, and the output of the level adjusting amplifier is determined in advance. A method is adopted in which it is primarily detected whether or not a certain level has been reached, and the output level from the head is set to an appropriate level by adjusting the gain of a level adjusting amplifier. The ARA area for adjusting the gain of the level adjustment amplifier is provided in the first part of the magnetic tape, and the gain of the level adjustment amplifier for proper writing and reading of the magnetic tape device is determined in the ARA area. Since adjustments are always made, the frequency of use increases, and as a result, the head output decreases due to deterioration in the performance of the magnetic tape, and the gain adjustment of the level adjustment amplifier becomes unable to work automatically, causing the magnetic tape device to fail. There is a problem that the process stops and subsequent processing becomes impossible. The present invention aims to solve the above-mentioned problems, and includes:
By making the detection level of the magnetic tape device variable multiplexing, it is possible to adjust the gain of the level adjustment amplifier to the optimum gain that suits the performance of the magnetic tape. It is an object of the present invention to provide an automatic gain adjustment processing method that reduces the occurrence of undesirable stop states.

Therefore, the automatic gain adjustment processing method of the present invention includes a preamplifier that amplifies the signal read from the head, a level adjustment amplifier that has the function of adjusting the gain to amplify the output from the preamplifier, and an output of the level adjustment amplifier. A level comparison circuit unit that compares the read signal level obtained based on a predetermined level, and a level setting means that sets the predetermined level, and the level comparison circuit unit In the gain adjustment method, the gain of the level adjustment amplifier is fixed, and an amplitude error is generated when the read signal level does not reach the predetermined level. The predetermined level is configured to be variable, and when the level comparison circuit section generates the amplitude error, the predetermined level from the level setting means is changed, and the gain is adjusted in the level adjustment amplifier. It is characterized by the fact that it has been re-executed.
This will be explained below with reference to the drawings. Figure 1 shows the conventional GCR
A configuration example of a read amplifier, FIG. 2 is an operation explanatory diagram explaining the operation of FIG. 1, FIG. 3 is an example configuration of the GCR read amplifier of the present invention, and FIG. An explanatory diagram of an operation to be explained is shown.

In the configuration example of a conventional GCR read amplifier shown in FIG. 1, numeral 1 is a head, 2 is a preamplifier, 3 is a level adjustment amplifier, 4 is a differential amplifier, 5 is a level comparison circuit, and 6
each represents a control circuit.

Preamplifier 2 is an amplifier that amplifies the read output of head 1.

The level adjustment amplifier 3 is an amplifier whose gain can be switched in accordance with gradation j over 2n steps using an n-bit digital signal. The differential amplifier 4 is an amplifier for detecting the peak of the signal read by the head 1. The level comparison circuit 5 is a group of comparators that detects the peak pulse from the analog waveform differentiated by the differential amplifier 4 and detects its amplitude using a fixedly set slice voltage Es. The control circuit 6 performs control to switch the gain of the level adjustment amplifier 3 in a gradation manner using a control signal, and also receives the appropriate amplitude output from the level comparison circuit section 5 to keep the gain of the level adjustment amplifier 3 constant. Fix it. Figure 2 shows the operating status of each part in Figure 1, where Es is the slice voltage set in the level comparison circuit section 5 in Figure 1, and the amplitude and error signal A is the level adjustment amplifier of Figure 1. Amplitude of the level comparison circuit section 5 when the gradation gain is the step-like curve A in FIG. 2 shows the amplitude error output of the level comparison circuit section 5 when the gradation gain of FIG. 2 shows the step-like curve B in FIG.

Note that SN°C indicates that automatic gain adjustment is in progress. In FIGS. 1 and 2, the slice voltage E is set to an optimal value within the standard range for reading and writing in a magnetic tape device.

When the head 1 enters the ARA area of the magnetic tape, the SAGC is turned on and gain adjustment of the write or read amplifier system of the magnetic tape device is started by inputting a control signal to the control circuit 6. A signal read from the head 1 is amplified by a preamplifier 2, and the gain is further adjusted stepwise by a level adjustment amplifier 3, which adjusts the gain to a predetermined amplification stepwise.

For example, when the magnetic tape is new or the magnetic tape is in good storage condition, the gradation gain adjustment of the level adjustment amplifier 3 is performed using the slice voltage E9 set in the level comparison circuit section 5 on the way to the final step 2n. There is a matching step C, and when the step C is reached, an appropriate amplitude output is obtained from the level comparison circuit section 5, and this output is used to control the gradation gain adjustment of the level adjustment amplifier 3 via the control circuit 6. fix the state. If the magnetic tape is used frequently or if the magnetic tape is stored in poor condition, the head output read from head 1 will decrease and the gain adjustment will reach the highest step 2, as shown by step curve B in Figure 2.
Also in case n, the predetermined gain adjustment cannot be performed and the above-mentioned slice voltage Es cannot be obtained.

Therefore, an amplitude error signal is generated from the level comparison circuit section 5. Unbridled error signal B in FIG. 2 indicates this condition. Level comparison circuit 5
When an amplitude error signal is issued from the magnetic tape device, it becomes impossible to adjust the gain of the amplifier system of the magnetic tape device, and the magnetic tape device stops after a certain period of time, making it impossible to perform subsequent processing. The magnetic tape device is magnetic tape A.
An extremely inconvenient situation may occur if, in the RA region, the adjustment cannot be made due to lack of gain in the amplifier system and the operation stops, and in particular, if reading becomes impossible.

For example, when the magnetic tape on which the only data is recorded is poorly stored, the performance of the magnetic tape deteriorates, the head output decreases, and the gain of the amplifier system cannot be obtained. Such magnetic tapes are required to be read regardless of the circumstances. Therefore, in the case of the present invention, the level comparison circuit section 5
The gain of the amplifier system of the magnetic tape device is automatically adjusted by lowering the slice voltage E5 set in the ARA area by one step or several steps, and the magnetic tape having the unique data is processed without stopping the magnetic tape device in the ARA area. It is suggested that you read the . Here, it may be possible to set the slice voltage Es of the level comparison circuit section 5 to a level lowered by one step or several steps from the beginning, but as a general rule, when reading a magnetic tape, it is necessary to read a normal one. If the slice voltage Es is lowered by one step or several steps from the beginning in accordance with the deteriorated magnetic tape, compatibility with other magnetic tape devices will be lost. In other words, there are standards for magnetic tape that guarantee a certain level of quality, and when writing to or reading from magnetic tape that conforms to these standards, it is necessary to ensure compatibility between all magnetic tape devices. Therefore, as mentioned above, the slice voltage Es of the level comparison circuit section 5 is set to 1 from the beginning.
When a magnetic tape is written with a step or several steps lowered, the head output becomes low when read by another magnetic tape device, and errors are more likely to occur when reading normal signals. In addition, when reading a regular magnetic tape with the slice voltage Es of the level comparison circuit section 5 lowered by one step or several steps from the beginning, the level adjustment amplifier 3
If the magnetic tape device is out of the adjustment range and the magnetic tape device stops or does not stop, the noise is interpreted as a normal signal, which also causes misreading. Therefore, it is inconvenient to lower the slice voltage E5 of the level comparison circuit section 5 by one step or several steps from the beginning, and even in the final step 2n of the gradation gain adjustment of the level adjustment amplifier 3, the gain of the amplifier system is lowered. If the adjustment cannot be made and the slice voltage Es does not match the slice voltage E8, it is desirable to lower the slice voltage Es by one step and perform the gain adjustment of the amplifier system again from the first step.

FIG. 3 shows the configuration of an embodiment of the GCR read amplifier of the present invention that performs the above operation, where numerals 1 to 6 correspond to those in FIG. 1, and 7 represents a slice voltage level setting section.

The slice voltage level setting section 7 receives the amplitude error signal from the level comparison circuit section 5 and sets the slice voltage E5.
This circuit sets the slice voltage E″5, which is one step lower than the level of , in the level comparison circuit 5.

Figure 4 is an operation explanatory diagram explaining the operation of each part in Figure 3.
A case is shown in which a slice voltage of a standard level Es and a level E''5, which is one step lower than the standard level Es, is set in the level comparison circuit unit 5 by the operation of the slice voltage level setting unit 7 shown in FIG.

In FIGS. 3 and 4, when SAGC becomes 0N, the slice voltage E for reading or writing in the magnetic tape device
In order to obtain s, gain adjustment of the amplifier system is performed using a control signal from the control circuit 6. The head output read by the head 1 in the ARA area of the magnetic tape is amplified via a preamplifier 2 and a level adjustment amplifier. The standard slice voltage Es from the slice voltage level setting section 7 set in the level comparison circuit section 5 is compared with the signal level of the differential amplifier 4 of the head output obtained from the head 1.
Until these values match, the signal is applied to the level adjustment amplifier 3 via the control circuit 6, and gradation gain adjustment is automatically performed as shown in FIG. Even at the final step 21 of the level adjustment amplifier 3, the level of the standard slice voltage from the slice voltage level setting section 7 is low due to deterioration of the magnetic tape, etc., and the level of the differential amplifier output from the head 1 is low. If they do not match, the level comparison circuit section 5 generates an amplitude error signal. The amplitude error signal is input to the slice voltage level setting section 7 and the level adjustment amplifier 3, and the slice voltage level setting section 7 compares the level of the slice voltage Fs, which is one step lower than the standard slice voltage Es, with the level comparison circuit section 5. , and the level adjustment amplifier 3 resets the gradation gain adjustment to the first step. Then, the gain of the level adjustment amplifier is increased in gradation again via the control circuit 6. The set slice voltage of the level comparison circuit section 5 is at the level of the slice voltage E''3, which is one step lower than the standard slice voltage E5, so that the slice voltage from the head 1 at any step of the level adjustment amplifier 3 The output of the differential amplifier and the slice voltage Ws match as shown in FIG. The level adjustment amplifier is fixed at the stage of the matched step.In addition, if the slice voltage E''6, which is one step lower than the standard slice voltage Es set in the level comparison circuit section 5, does not match the level adjustment amplifier. As explained above, the Z amplitude error signal is generated again from the level comparison circuit section 5, and the slice voltage E''5, which is further lowered by one step, acts on the slice voltage level setting section 7 and is applied to the level comparison circuit section. 5, and the gain of the amplifier system is adjusted.

As explained above, according to the present invention, the gain of the standard magnetic tape is automatically adjusted using the standard slicing voltage of the magnetic tape device, so that it can be read and written normally as before, and can be used by other magnetic tape devices. compatibility with
Even if the performance of the magnetic tape is degraded, especially when reading a magnetic tape that has only data, the gain is adjusted using the standard slice voltage, and then the slice voltage is lowered to improve the performance of the magnetic tape device. Since the gain adjustment is done in gradation again, it is impossible to adjust the gain in the ARA area of the magnetic tape, but the magnetic tape device stops and subsequent processing becomes impossible, i.e. reading the magnetic tape that has the only data. This makes it possible to avoid a situation where it becomes impossible to do so.

[Brief explanation of the drawing]

Figure 1 shows an example of the configuration of a conventional GCRlJ-de amplifier;
The figure shows an operation explanatory diagram explaining the operation of FIG. 1, FIG. 3 shows the configuration of an embodiment of the GCR read amplifier of the present invention, and FIG. 4 shows an operation explanatory diagram explaining the operation of FIG. 3. . In the figure, 1 is a head, 2 is a preamplifier, 3 is a level adjustment amplifier, 4 is a differential amplifier, 5 is a level comparison circuit section, 6 is a control circuit, and 7 is a slice voltage level setting section 7, respectively.

Claims (1)

[Claims] 1. A preamplifier that amplifies the signal read from the head, a level adjustment amplifier that has the function of adjusting the output from the preamplifier to the gain to be amplified, and a read signal level obtained based on the output of the level adjustment amplifier in advance. A level comparison circuit unit that compares with a predetermined level and level setting means that sets the predetermined level are provided, and the gain of the level adjustment amplifier is fixed based on the output from the level comparison circuit unit. It is configured as follows,
and in the gain adjustment method in which an amplitude error is generated when the read signal level does not reach the predetermined level, the predetermined level from the level setting means is configured to be variable; The automatic gain is characterized in that when the comparator circuit unit generates the amplitude error, the predetermined level from the level setting means is changed, and gain adjustment in the level adjustment amplifier is performed again. Adjustment processing method.