JPH034605A - High speed waveform simulation device - Google Patents

Abstract

PURPOSE:To control a time axis and an amplitude as to each pulse waveform by providing an isolated waveform data generating means and generating and outputting an individual pulse with an amplitude designated by an amplitude parameter of an isolated waveform at a position designated on a time axis with the time axis parameter of the isolated waveform. CONSTITUTION:A trigonometric function data to convert a phase data into an isolated waveform data is written in memories 5, 6. The sum of output data of the memories 5, 6 added by an adder 7 is a cos wave with an amplitude component parameter An and the amplitude An is added to the cos wave and shifted by the amplitude. An isolated waveform data out outputted from the adder 7 is inputted to a D/A converter 8, converted into an analog signal waveform and outputted through a low pass filter 9. Thus, the frequency component of the isolated waveform is contained almost within a predetermined range. Thus, the frequency component within the range is generated to reproduce the original isolated waveform strictly based on the sampling theorem.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a high-speed waveform simulation device, and more specifically, the present invention relates to a high-speed waveform simulation device, and more specifically, the peak position and amplitude of a high-speed signal such as a disk read signal used for testing a reading circuit of a magnetic disk device. Concerning the control of

<Prior Art> For example, when testing a reading circuit of a magnetic disk device, a standard disk read signal read from the magnetic disk is required.

Therefore, at present, there are two methods: 1. Using the well-proven disk read signal of a standard disk device; 2. Digitally creating a data string of the disk read signal waveform and writing it into memory 1 as shown in Figure 11. The data string is read out from memory 1 and sent to the D/A converter (
DAC) 2 and its converted signal is passed through a low-pass filter (L
PF) 3, etc. are used.

<Problems to be solved by the invention> However, according to the method (2), the scale of the equipment becomes large, and due to the presence of mechanical parts, characteristics vary depending on the equipment.
This method has problems such as being difficult to use for noise limit tests because the data cannot be changed dynamically.

Furthermore, according to method (2), it is not possible to make the sampling frequency of the D/A converter 2 sufficiently larger than the rate of the actual high-speed disk read signal waveform, and the disk read signal waveform is shown in FIG. As such, it must be reproduced at several to ten-odd sampling points per pulse, as indicated by O marks.

This means that the waveform of the data string at the sampling point and the D/A
Indicates that the waveforms after conversion and filtering do not match exactly. Normally, the disk read signal detects the peak of the waveform and reads data 0.1 from that position on the time axis, so the peak position of the waveform is an important factor. The peak position cannot be determined by simply controlling the data string, and the peak position of the disc read signal cannot be sufficiently controlled by simply controlling the data string.

The present invention has been made with attention to these points,
The purpose is to provide a high-speed waveform simulation device that can control the time axis and amplitude of each pulse waveform.

Means for Solving the Problems> The present invention for solving the above problems comprises: isolated waveform data generation means for generating isolated waveform data in which the time domain is divided and the frequency domain is limited; and the isolated waveform data generation means. A D/A converter that converts isolated waveform data output from the D/A converter into an analog signal, and a low-pass filter that removes components of the sampling clock frequency of the output signal of the D/A converter that are equal to or higher than 1/2. It is characterized by:

Effect> The isolated waveform data generating means generates and outputs an individual pulse having an amplitude specified by the amplitude parameter of the isolated waveform at a position specified on the time axis by the time axis parameter of the isolated waveform. Thereby, the peak position of each individual pulse can be controlled using the minimum number of sampling points with a resolution greater than the time resolution of the sampling points.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a basic configuration diagram of the present invention. In the figure, an adder 1 integrates input sampling frequency data f to generate continuously changing phase data phase.

By changing the sampling frequency data f, the number of samples per isolated waveform can be controlled. The adder 1
The output data is input to the first addition terminals of adders 3 and 4, respectively. Inverse trigonometric function data (for example, Co5-1) for converting the amplitude component parameter An of the isolated waveform shown in FIG. 2 into a phase is written in the memory 2. The output data of the memory 2 is input to the third addition terminal of the adder 3 and the subtraction terminal of the adder 4, respectively. The time axis component parameter Tn of the isolated waveform shown in FIG. 2 is input to the second addition terminal of the adder 3.4. In addition,
A zero signal 1fZero is manually applied to the reset terminals of these adders 3.4 when there is no signal. Trigonometric function data (for example, COS) as shown in FIG. 3 for converting phase data into isolated waveform data is written in the memory 5.6. The adder 7 is for generating the final waveform data out, the output data of the memory 5 is input to the first addition terminal, the output data of the memory 6 is input to the second addition terminal, The amplitude component parameter An of the isolated waveform is input to the third addition terminal. Here, memory 5
．． The sum of the output data of 6 is the CO of the amplitude component parameter An.
This becomes an S wave, and the 808 waves are shifted by that amount by adding the amplitude component parameter An. The solitary waveform data out output from the adder 7 is sent to the D/A converter 8.
The analog signal waveform is inputted to , and converted into an analog signal waveform, and the analog signal waveform is output to 10 through a low-pass filter 9 . A sampling clock generator 11 supplies a sampling clock as a master clock to each section.

As mentioned above, in the present invention, one of the trigonometric functions is used as an isolated waveform.
Use cycles. As a result, the frequency components of the isolated waveform are approximately within a predetermined range. Therefore, by generating frequency components within this range, the original isolated waveform can be precisely reproduced based on the sampling theorem.

The time axis resolution of the reproduced waveform is larger than the sampling time. FIG. 4 is an explanatory diagram of these relationships. The isolated waveform is expressed as 1-cos(2πt/T). However, 0≦t≦T. When outputting the isolated waveform through a D/A converter, if the frequency band of the waveform to be output is limited, the signal can be reproduced by setting the sampling frequency f19 to more than twice the upper limit of the band. In FIG. 4, it can be seen that the sampling frequency f Ip should be set to 4/T. That is, it is sufficient to sample at four or more points per isolated waveform. If you want to output a waveform with an accuracy of 1% or less, change the sampling frequency f sp to 13/T.
Just do it.

Furthermore, since a trigonometric function table is used in this way, by using the system of amplitude component parameters An shown in FIG. 1, it is possible to obtain isolated waveform data whose amplitude is modulated only by the adder as shown in FIG. 5. You can also do it.

By generating such an isolated waveform at a necessary timing, a digital signal having an amplitude as shown in FIG. 6 can be continuously generated.

FIG. 7 is a block diagram of a specific example of the present invention, and parts common to those in FIG. 1 are given the same reference numerals and their redescription will be omitted. In the figure, reference numerals 12 and 13 are isolated waveform generating sections respectively surrounded by broken lines in FIG. 1, and each outputs two isolated waveform data outl and out2 at the same time. The isolated waveform data outl and out2 are input to an addition terminal of an adder 14 and added. The adder 1
The output data of 4 is input to a D/A converter 8 and converted into an analog signal.

T 2 n input to each isolated waveform generator 12.13
+T2□1 is phase shift data from the standard peak positions pA, pB of isolated waveforms A and B that are continuously overlapped as shown in FIG. 8, and is used to create a peak shift in the disk read signal waveform. In addition, each isolated waveform generating section 12.1
A2.3 input to A2.3. , A2°+1 is amplitude data that specifies the amplitude of isolated waveforms A and B that are successively overlapped as shown in FIG. 9, and corresponds to a missing pit in the disk read signal waveform.

FIG. 10 is an output waveform diagram of FIG. 7. As the sampling frequency f, 4/T, which is the above-mentioned minimum frequency when T is the time width of the isolated waveform, was selected. In order to obtain an accuracy of 1% or less, 8/T may be selected as the frequency. In FIG. 10, five isolated waveforms A to E are superimposed.

First, T and A1 in FIG. 10 are given as T2° and A2o input to the isolated waveform generator 12. As a result, generation of the desired isolated waveform A begins. It is necessary to generate the second isolated waveform B during the generation of the first isolated waveform A. The isolated waveform B is input to the isolated waveform generator 13 at T 2
T2 and A2 in Figure 10 as n+I+ A21111
give. As a result, generation of the desired isolated waveform B begins. After the output of the isolated waveform A from the isolated waveform generator 12 is finished, preparations are made to generate the third isolated waveform C by giving T3 and A3 as T2n+A2a. Thereafter, by repeating the same procedure, isolated waveforms are generated alternately from each isolated waveform generating section 12, 13. Then, these are added by an adder 14 and the output data is D
In addition to the /A converter 8, the target output waveform F is obtained through a low-pass filter 9 which converts the signal into an analog signal and removes frequency components of 1/2 or more of the sampling frequency.

In the above embodiment, a Hanning window shape is used as the isolated waveform, but the conditions required for the isolated waveform are that the time domain is divided and the frequency is different.

It is sufficient that the components exceeding a certain range of several regions are sufficiently small.
As the isolated waveform that meets these conditions, various windows used in DSP processing, such as a Hamming window, can be used.

Further, in the above embodiment, the waveform generation means is constituted by a hardware circuit, but it is also possible to calculate the desired waveform data in advance using software, write it in the memory, read out the waveform data, and use the D/A. The signal may be converted into an analog signal using a converter.

<Effects of the Invention> As described in detail above, according to the present invention, a high-speed waveform suitable for a disk read signal, etc. used for testing a reading circuit of a magnetic disk device, in which the time axis and amplitude of each pulse waveform can be controlled. A simulation device can be provided.

[Brief explanation of the drawing]

Figure 1 is a basic configuration diagram of the present invention, Figure 2 is a conceptual diagram of an isolated waveform, Figure 3 is an explanatory diagram of a trigonometric function table written in memory, and Figure 4 is an explanation of the relationship between the isolated waveform and sampling frequency. 5 is a block diagram for amplitude modulation, FIG. 6 is a side view of the output waveform, FIG. 7 is a block diagram of a specific example of the present invention, and FIGS. 8 to 10 illustrate the operation of FIG. 7. FIG. 11 is a configuration diagram showing an example of a conventional device, and FIG. 12 is a waveform diagram explaining the operation of FIG. 11. 1, 3.4.7. 14... Adder 2... Inverse trigonometric function memory 5.6... Trigonometric function memory 8... D/A converter (DAC) 9... Low pass filter <L P F) 10... Output terminal 11...Sampling clock generator 12.13...
・Isolated waveform generation part Less than a few percent of the original signal Figure 8 Figure 9 Section 11 Figure 12

Claims (1)

[Scope of Claims] An isolated waveform data generating means for generating isolated waveform data in which the time domain is divided and the frequency domain is limited, and converting the isolated waveform data output from the isolated waveform data generating means into an analog signal. A high-speed waveform simulation device comprising: a D/A converter; and a low-pass filter that removes a component of a sampling clock frequency of 1/2 or more of an output signal of the D/A converter.