JP2730067B2 - Arbitrary waveform generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for generating an arbitrary waveform, and more particularly to an arbitrary waveform generator suitable for use in a magnetic disk inspection apparatus.

<Prior Art> When data is stored in a magnetic disk drive, a signal is generated by modulating the data to be stored, and the signal is used to drive a magnetic head to form and store a predetermined magnetization pattern on the disk surface. . Such data modulation methods include
NRZI (Non Return to Zero Inverse), FM (Frequency
Moduration), MFM (Modified Frequency Moduration)
Etc. The modulation method of the FM method will be described with reference to FIG. FIG. 8 shows a data pattern of "42" expressed in hexadecimal, and a pulse is generated only when the data pattern is "1". (A) represents data to be stored, and (B) represents a clock. The data after FM modulation is data (A) to be stored and a clock (B) added thereto as shown in (C).
At the timing of the modulation data shown in (C), the magnetization pattern on the disk surface is inverted and stored. Therefore, the waveform read by the magnetic head is as shown in FIG. That is, since the magnetization pattern changes at the timing of the modulation data, the output becomes maximum at that timing, and appears positively and negatively. C and D in the figure represent clock and data, respectively. In a magnetic disk drive inspection apparatus, it is necessary to create this readout waveform. However, this readout waveform varies depending on the data to be stored and the modulation method, and is not constant. In addition, when the storage density increases, the read waveforms interfere with each other, causing a so-called peak shift in which the phase shifts. Therefore, in order to examine the influence of the peak shift, a waveform whose phase is arbitrarily shifted is generated. You also need.

In order to generate such a readout waveform, the readout waveform is defined in the form of a function expression and generated by calculation, or data corresponding to the waveform is input from a keyboard or the like.

<Problem to be solved by the invention> However, in the method of defining a modulation waveform in the form of a function, the waveform that can be defined is limited, and there is a problem that it is difficult to generate an arbitrary waveform. Another problem is that it is difficult to obtain the function formula itself.

Although the method of inputting data has the advantage that an arbitrary waveform can be generated, the number of input data is large,
There was a problem that it took time to input. It is conceivable to previously store the waveforms corresponding to the respective data, but since the waveforms differ depending on the data and the modulation method to be stored on the disk, there are many types, and it is practically impossible.

<Object of the Invention> It is an object of the present invention to provide an arbitrary waveform generator capable of generating an arbitrary modulation waveform by a simple operation.

<Means for Solving the Problems> In order to solve the problems, the present invention provides a basic waveform output unit that stores basic waveform data, and a modulation data generation unit that generates a signal that defines the appearance timing of the basic waveform data. With the output of the modulation data generating section, waveform synthesis for capturing the basic waveform data of the basic waveform output section or inverting the sign of the basic waveform data according to a desired rule and capturing the synthesized basic waveform data to synthesize the captured basic waveform data. And a part.

<Embodiment> FIG. 1 shows an embodiment of an arbitrary waveform generator according to the present invention. In FIG. 1, reference numeral 10 denotes a basic waveform generator, which generates, for example, one peak waveform. Reference numeral 11 denotes a modulation data generation unit that generates a signal indicating a timing at which the peak waveform appears. Reference numeral 12 denotes a waveform synthesizing unit which takes in the output of the basic waveform generating unit at the timing of the output signal of the modulation data generating unit 11, synthesizes the output, and outputs it.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 2A shows the FM-modulated data shown in FIG. 8C, which is output from the modulated data generator 11. 13
Is a basic waveform output from the basic waveform generating unit 10, and the waveform synthesizing unit 12 captures the fundamental wave 13 such that the position of the pulse of the FM modulation data in (A) is at the center of the peak of the fundamental wave 13. . As described above, since the sign of the read output of the magnetic disk is alternately inverted, the waveform synthesizer 12
Is alternately inverted and taken in. The captured waveform is as shown by a dotted line 14. Generally, since the FM-modulated data is generated close to each other, the captured fundamental wave is overlapped at the base. The waveform synthesizing unit 12 adds the overlapped portions and outputs the result as a synthesized waveform 15.

FIG. 3 shows a specific configuration of this embodiment. In this figure, reference numeral 16 denotes a microprocessor, and a RAM 17 thereof, a ROM 19, a keyboard 20, and a video RAM 21 are connected to a bus 17 thereof. The microprocessor 16 generates a modulated signal as shown in FIG. 2A based on data input from the keyboard 20 by a program stored in the ROM 19, and stores the modulated signal in the RAM 18 based on the signal. The data of the fundamental wave is read out and stored at a predetermined address of the video RAM 21. The address of the video RAM 21 corresponds to the time axis of the output signal, and the microprocessor 16 calculates the address of the video RAM based on the generated modulated signal, and newly stores the data stored in the address and the RAM 1.
The data of the fundamental wave read from 8 is added and stored at that address. Thus, FIG. 2 (B)
The composite waveform 15 shown in FIG. The composite waveform stored in the video RAM 21 is converted into an analog signal, output to the outside, and displayed on the CRT 22.

FIG. 4 shows a flowchart of the operation. First, input the waveform of the fundamental wave. The fundamental wave is generated by inputting waveform data from the keyboard 20 and stored in the RAM 18. Also, data of several kinds of fundamental waves are stored in advance,
You may make it select. Next, a data pattern is defined. Normally, it is defined in 16-bit units. Next, input the clock frequency and modulation method and press the execution key. The microprocessor 16 synthesizes a waveform from the input data, stores it in the video RAM 21, and outputs it.

Since the data pattern is usually defined by a length of 16 bits, it is sufficient for the video RAM 21 to have 16 bits, but depending on the pattern of the modulated data, the modulation between the first 16 bits and the next 16 bits is sufficient. It may collapse. This example is shown in FIG. FIG. 5A shows data “A511”.
This represents a fundamental wave of data obtained by performing NRZI modulation of (1010010100010001 in binary). In this case, the last fundamental wave 23 of the first 16 bits and the first fundamental wave 24 of the next 16 bits are connected and the waveform is not disturbed, but “A5” shown in FIG.
In the case of “13” (1010010100010011 in binary), the modulation of the last fundamental wave 25 of the first 16 bits and the first fundamental wave 26 of the next 16 bits is disturbed at the connection unit 27. Therefore, the length of the video RAM 21 is set to 32
As shown in (C), the waveform of the first 16 bits is inverted to obtain the waveform of the next 16 bits.
In this way, the modulation at the connection section 27 is not broken. FIG. 6 shows the case of FM and MFM modulation in the same data “A513”. (A) shows the case of FM and (B) shows the case of MFM. In each case, the waveform of the first 16 bits is inverted to be the waveform of the next 16 bits. . In other words, when 16-bit data is represented by a binary number, if “1” is an even number, the first 16-bit waveform is copied as it is to form the next 16-bit waveform,
If the number is odd, the first 16-bit waveform is inverted to form the next 16-bit waveform.

FIG. 7 shows another method of creating a composite waveform. In this figure, reference numeral 28 represents a fundamental wave, and 29 represents a position of an output pulse of the modulation data generating unit. (A) is a case where the fundamental wave is not generated alternately in the positive and negative directions. In the above-described embodiment, the fundamental wave is set to have positive and negative values alternately because it is made to correspond to NRZI, FM, and MFM modulation. However, as shown in FIG. You may do so. (B) is a diagram in which several types of waveforms of the fundamental wave are prepared and appropriately changed. In this way, a complicated waveform can be generated relatively easily.

In order to simulate a peak shift, a fundamental wave may be given with a phase shifted from the modulation data pattern.

<Effects of the Invention> As described above in detail with reference to the embodiments, in the present invention, the basic waveform data generated by the basic waveform generator is read out based on the modulation data generated by the modulation data generator. To generate an arbitrary waveform. Therefore, it is possible to easily generate an arbitrary waveform, and there is no limitation on the waveform that can be generated unlike the case of generating a function. In particular, this is suitable for a case where a waveform in which a small number of basic waveforms can be repeatedly generated at an arbitrary frequency, that is, a waveform for reading a magnetic disk is created.

In addition, since the basic waveforms are combined, it is possible to cope with an arbitrary modulation method, and it is also possible to easily perform an operation such as shifting the phase.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an arbitrary waveform generator according to the present invention, FIG. 2 is a diagram for explaining a procedure of waveform synthesis, FIG. 3 is a block diagram showing a specific configuration, FIG. FIG. 4 is a flow chart showing the procedure of the preparation, FIGS. 5 to 7 are waveform diagrams for explaining another embodiment, and FIG. 8 is a block diagram showing the configuration of a conventional waveform generator. 10 …… Basic waveform generator, 11 …… Modulation data generator, 12…
... Waveform synthesis unit.

Claims (1)

(57) [Claims] 1. A basic waveform output unit for storing basic waveform data, a modulation data generation unit for generating a signal defining the timing of appearance of the basic waveform data, and an output of the modulation data generation unit, the basic waveform output unit Capture the basic waveform data of the section, or invert the sign of the basic waveform data according to the desired regulation,
An arbitrary waveform generator, comprising: a waveform synthesizing unit that synthesizes the acquired basic waveform data.