JPS6055910B2 - Minimum level detection method in magnetic storage media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A conventional method for determining the quality of a magnetic tape on which digital information is stored is to set a threshold level, read the digital information on the magnetic tape with a read head, and then increase the output of the read head. The above threshold hold,
This is to check whether it is lower than the level.

With the conventional method described above, it is possible to detect a degraded portion where the readout output level is slightly higher than the threshold portion, although it is degraded. There are deficiencies that cannot be determined. The present invention is based on the above considerations, and is based on a magnetic storage medium that allows the minimum peak value of the read head output to be known by just one run of the magnetic storage medium and determines how much margin exists. The purpose is to provide a minimum level detection scheme in media. Therefore, the minimum level detection method for a magnetic storage medium of the present invention is applicable to a magnetic surface storage device comprising a read head that reads digital information from a magnetic storage medium in which digital information is stored, and an amplifier that amplifies the output of the read head. In the apparatus, a minimum value detection storage means is provided connected to the output side of the amplifier, and the minimum value detection storage means detects a minimum peak value of the amplified read head output and holds the minimum peak value. This is a characteristic feature. below,
The present invention will be explained with reference to the drawings. The figure is 1 of the present invention.
It is a block diagram of an embodiment, and 1 is a magnetic tape, 2 is a magnetic head, 3 is an amplifier, 4 is a comparison type minimum value detection circuit, and 5
-1 and 5-2 are memories, 6-1 and 6-2 are display devices, 7
is a digitizing amplifier, 8 is a NAND gate, WT is a write signal terminal, CHP is a checkpoint terminal, and A is an amplified read head output.

The illustrated magnetic tape device is of a cassette type, and information is stored on the magnetic tape 1 using, for example, a PE (Phase Encode) method. The digital information on the magnetic tape 1 is read by a read head of a magnetic head 2;
It is amplified by amplifier 3.

The amplified read head output is amplified and shaped by an amplifier 7 and a NAND gate 8, thereby obtaining a digital signal. The amplified read head output A normally has a peak-to-peak value of about 5 volts.
Although it is possible to retrieve digital information even when the peak-to-peak value is on the order of 2 volts, as mentioned above, it is necessary to quickly detect a drop in the level of the read head output. Comparison type minimum value detection circuit 4, memory 5
-1, 5-2 and display devices 6-1, 6-2 are provided for this purpose. The comparative minimum value detection circuit has a function of separately detecting the peak value on the (+) side and the (-) side. The minimum peak value on the (10) side is held in the memory 5-1, and the minimum peak value on the (1) side is held in the memory 5-1.
-2. Note that the memories 5-1 and 5-2 can also be registers. Comparison type minimum value detection circuit 6
converts the peak value of the input analog signal into a digital signal. Then, the peak value on the (+) side is stored in memory 5.
-1, and if the former is smaller than the latter, the contents of memory 5-1 are updated. Similarly, the peak value on the (-) side is compared with the contents of the memory 5-2, and if the former is smaller than the latter, the contents of the memory 5-2 are updated. After all the digital information on a roll of magnetic tape has been read,
The contents of memory 5-1 and memory 5-2 are converted into w-adic numbers and displayed on display devices 6-1 and 6-2, respectively. Magnetic tape devices are generally equipped with a counter that counts the number of blocks or a counter that counts the length from the end.Using this type of counter,
The position on the magnetic tape where the minimum peak value was recorded can be recorded.

For this purpose, for example, a third memory is provided, and the memory 5-
The contents of the counter may be written into the third memory every time the contents of 1 or 5-2 are updated. In this case, a display device may be provided to display the contents of the third memory. As is clear from the above explanation, according to the present invention, it is possible to know the minimum peak value of the read head output just by running the magnetic storage medium once, and from this it is possible to determine how much margin there is. You can.

[Brief explanation of the drawing]

The figure is a block diagram of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Magnetic tape, 2...Magnetic head, 3...Amplifier, 4...Comparison type minimum value detection circuit, 5-1 and 5-2
...Memory, 6-1 and 6-2...Display device, 7...
・Amplifier, 8...NAND gate.

Claims (1)

[Scope of Claims] 1. A magnetic surface storage device comprising a read head for reading digital information from a magnetic storage medium in which the digital information is stored, and an amplifier for amplifying the output of the read head; Minimum level in a magnetic storage medium, characterized in that there is provided a minimum value detection storage means connected, the minimum value detection storage means detects a minimum peak value of the amplified read head output and holds the minimum peak value. Detection method. 2. Minimum level detection in a magnetic storage medium according to claim 1, characterized in that the minimum value detection storage means holds the minimum peak value on the + side and/or - side of the amplified read head output. method.