JPH0423442B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] This is a circuit diagnosis method for a circuit system including an AGC circuit.
In order to solve the problem that accurate margin diagnosis of the circuit is impossible due to the amplitude adjustment function of the circuit, the amplitude level of the pseudo data signal to be injected for circuit diagnosis is switched in multiple stages. This enables accurate margin diagnosis in a simple manner.

[Industrial application field]

The present invention relates to a circuit diagnosis method for a circuit system including an AGC circuit.

For example, LWR
(Loop Write Read) method is adopted.

This is to diagnose the circuit operation of the write/read circuit system by directly injecting a pseudo data signal from the write circuit system into the read circuit system instead of the read signal from the read head.

It is desired that such a circuit diagnosis method be able to more accurately diagnose circuit operation using a simple method.

[Conventional technology]

FIG. 3 shows a block diagram illustrating a conventional example.
The block diagram shown in FIG. 3 shows the general functional blocks of the write circuit system 1 and the read circuit system 2 of the magnetic tape device, and its configuration consists of a modulation circuit 1 that modulates write data into a predetermined format.
1, a write amplifier 12 that creates magnetic recording data according to the modulation data from the modulation circuit 11, and a write head 13 that magnetically records data on the magnetic tape a according to the output from the write amplifier 12. A write circuit system 1, a read head 21 that reads data magnetically recorded on the magnetic tape a and converts it into a predetermined electrical signal, a read amplifier 22 that amplifies the read data from the read head 21 to a predetermined level, and a read amplifier. an AGC circuit 23 that detects fluctuations in the amplitude of the signal from the AGC circuit 22 and automatically controls the gain to keep the amplitude of the output signal constant; and a demodulation circuit that demodulates the output from the AGC circuit 23 into a predetermined data signal. 34, a read circuit system 2 comprising an adder 25 for adding read data from the read head 21 and data from the write circuit system 1, and an amplitude detection section 3 for detecting the amplitude of the output from the AGC circuit 23. , and a control section 4 that diagnoses the read circuit system 2 based on the state of the detection signal from the amplitude detection section 3.

When diagnosing the operation of the read circuit system 2 using the LWR method, the write amplifier 12 of the write circuit system 1 is directly connected to the adder 25 in the read circuit system 2 via the lead wire b according to instructions from the control unit 4. do.

In this state, a pseudo data signal (also called an LWR data signal, which has a waveform equivalent to the output of the read head 21) input via the modulation circuit 11 is injected into the read circuit system 2.

The pseudo data signal level at this time is a single level, the amplitude of the output from the AGC circuit 23 is detected by the amplitude detector 3, and the operation of the read circuit system 2 is diagnosed based on the detected amplitude state.

[Problem that the invention seeks to solve]

As mentioned above, when diagnosing the operation of the read circuit system 2 that includes the AGC circuit 23, the AGC circuit 2
Since the operation by the amplitude adjustment function of No. 3 is included, accurate circuit diagnosis is impossible.

That is, the detection signal detected by the amplitude detection section 3 is
The noise is absorbed within the amplitude adjustment function of the AGC circuit 23, making it impossible to judge the noise margin and making the diagnosis of the AGC circuit 23 itself uncertain.

On the other hand, in order to eliminate the influence of the amplitude adjustment function of the AGC circuit 23, it is necessary to fix the AGC circuit 23 at a constant value.

However, even in this case, since the pseudo data signal level is a single level, the problem of inability to determine the noise margin cannot be solved.

[Means for solving problems]

The above problem can be solved by the present invention, which includes a write circuit system consisting of a modulation circuit that modulates write data into a predetermined format, a write amplifier that creates magnetic recording data according to the modulated data, and a write head, a read head, and a read head. A read circuit system consisting of a read amplifier that amplifies data to a predetermined level, an AGC circuit and a demodulation circuit that detect fluctuations in the amplitude of the signal and automatically control the gain to keep the amplitude of the output signal constant. An amplitude switching section, an amplitude detection circuit, and a control section are provided for the configuration, and the amplitude switching section converts the pseudo data signal extracted from the write amplifier of the write circuit system to the upper and lower limits of the adjustment range of the AGC circuit. The output of the AGC circuit is converted into a multi-stage amplitude including two levels, and the amplitude of each stage is selected by the control of the control unit and inserted into the read amplifier of the read/write system.The output of the AGC circuit is detected by the amplitude detection circuit. The problem is solved by a circuit diagnosis method characterized in that the results are given to the control section.

[Effect]

That is, the pseudo data signal from the write amplifier of the write circuit system shown in FIG. 3 is converted into multi-stage amplitude by the amplitude switching means 50 shown in FIG. This is inserted into the read circuit system 2, and the read circuit system is diagnosed.

〔Example〕

The gist of the present invention will be specifically explained below with reference to an embodiment shown in FIG.

FIG. 2 shows a block diagram illustrating an embodiment of the invention. Note that the same reference numeral indicates one object throughout the figures.

The embodiment of the present invention is for accurately diagnosing the operation of the read circuit system 2 including the AGC circuit 23, and the diagnosis method is carried out by the following method.

That is, the control unit 4 sends instructions for diagnosing the read circuit system 2 including the AGC circuit 23 to the write circuit system 1.
and to the lead circuit system 2.

As a result, the write circuit system 1 activates the lead b and sends the LWR data as a pseudo data signal through the modulation circuit 11 to the amplitude switching section 50 through the write amplifier 12.

The amplitude switching unit 50 converts the input LWR data into multi-level levels, which can be individually switched and output under the control of the control unit 4.
5 into the amplifier 22, the amplitude of the signal output from the AGC circuit 23 at that time is detected, and the control unit 4 confirms that all the amplitudes are constant.

Note that the LWR data level to be inserted is at least two levels, the upper and lower limits of the adjustment range of the AGC circuit 23.

Note that the amplitude switching section may be incorporated into the write amplifier of the write circuit system.

Also, as LWR data, a signal waveform equivalent to that input from the read head 21 is injected and demodulated by the demodulation circuit 24. When the LWR data level is high (in this case, the S/N ratio is good), the signal waveform equivalent to that input from the read head 21 is injected. (in this case, the S/N ratio is poor), the noise margin of the read circuit system 2 is determined.

In this way, the circuit configuration is made as simple as possible, and furthermore, in the case of this embodiment, fixing operation of the AGC circuit 23 is not required. Furthermore, multi-level
By injecting LWR data, various margin-based diagnosis becomes possible.

〔Effect of the invention〕

According to the present invention as described above, there is an effect that a circuit system including an AGC circuit can be diagnosed more accurately and in a simpler manner.

[Brief explanation of drawings]

FIG. 1 is a block diagram explaining the principle of the present invention.
FIG. 2 is a block diagram explaining an embodiment of the present invention;
FIG. 3 shows a block diagram explaining a conventional example. In the figure, 1 is a write circuit system, 2 is a read circuit system, 3 is an amplitude detection section, 4 is a control section, 11 is a modulation circuit, 12 is a write amplifier, 13 is a write head, 21 is a read head, 22 is a read amplifier,
23 is an AGC circuit, 24 is a demodulation circuit, 25 is an adder, and 50 is an amplitude switching section (amplitude switching means).

Claims (1)

[Claims] 1 A write circuit system consisting of a modulation circuit that modulates write data into a predetermined format, a write amplifier that creates magnetic recording data according to the modulated data, and a write head, a read head, and amplifies the read data from the read head to a predetermined level. The amplitude A switching section, an amplitude detection circuit, and a control section are provided, and the amplitude switching section converts the pseudo data signal extracted from the write amplifier of the write circuit system into a multi-stage signal including two levels, the upper and lower limits of the adjustment range of the AGC circuit. Convert it to amplitude, select the amplitude of each stage under the control of the control unit, and insert it into the read/write system read amplifier.
A circuit diagnostic method characterized in that the output of the AGC circuit is detected by an amplitude detection circuit, and the detection result is provided to a control section.