JPS5960712A - Data discriminating device - Google Patents

Abstract

PURPOSE:To obtain a data discriminating circuit which has no effect to discrimination of data despite a waveform inversion, by measuring the time from the leading edge (trailing edge) of a signal through the leading edge (trailing edge) of the next signal, calculating the frequency of an audio signal from the measured time and deciding whether the calculated frequency is included within a prescribed range. CONSTITUTION:A CPU3 calculates the frequency of an audio signal (a) under detection from a period of time points t1-t3 showing a cycle of the signal (a) which is written in different registers. Then the CPU3 compares this calculated frequency with a frequency set previously to decide the frequency range and then discriminates the data ''0'' or ''1'' of the region comprising the signal (a) of the decided frequency. For instance, if the calculated frequency is equal to 1,250Hz, this frequency value is included in a range of 1,100-1,300Hz. Therefore, the CPU3 discriminates the data of the region comprising the signal (a) of 1,250Hz frequency as ''0''.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a method for inputting an audio signal from an external storage device,
The data in the area consisting of the audio signal is 110
The present invention relates to a data discriminating device for discriminating between ``7j'' and ``1''.

[Technical background of the invention and its problems]

Generally, when using a personal computer, a home tape recorder is used as an external storage device because of its low cost. In such cases, the tone burst method and the FM modulation method are used as methods for recording data. A simple explanation of both methods is:
The tone burst method is a method for recording data in such a way that it can be determined whether the data is 1" or "oII" depending on whether or not an audio signal is recorded. ``For example, the audio signal waveform of 1200Hz is 24.001''! This is a recording method that allows discrimination based on the audio signal waveform of z. In addition, as a circuit for discriminating data from a tape recorded using this method, a frequency discrimination circuit (PLL, etc.) is used.
, a level discrimination circuit, etc. are used. However, the tape used in tape recorders is originally designed for recording audio signals. For this reason, the waveforms recorded on tape using the method described above are
It may easily reverse during playback or due to fluctuations in motor rotation. When this happens, the data discrimination circuit described above cannot stably discriminate data.

[Purpose of the invention]

The present invention has been made in view of these drawbacks, and its object is to provide a data discrimination circuit that does not affect data discrimination even if waveform inversion occurs.

[Summary of Hatsutsu]

Therefore, we developed a comparator that inputs an audio signal from the external storage device u2 and outputs a signal when the audio signal exceeds a certain level, and a comparator that outputs a signal when the audio signal is above a certain level, and a to the next i=
Measures the time from the rise of the signal to C (fall is 9), calculates the frequency of the audio signal from that time, determines whether the frequency is included in a predetermined frequency range, and detects it. The data in the area consisting of audio signals ""oj
and a discriminating means for discriminating whether l is 1''.

[Embodiments of the invention]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a circuit according to this embodiment. In the figure, 1 is a comparator.

The comparator 1 is a circuit that inputs an audio signal a from an external storage device (not shown) and outputs a signal when the audio signal a is at a certain level or higher. In addition, when the audio signal a as shown in FIG. Time is output. Also, 2 is I10
3 is a CPU, and 4 is a timer. I10 port 2 outputs a signal of "1" when the output signal of comparator 1 is present, and outputs a signal of "0" when the output signal of comparator 1 is absent.
Outputs the signal. Timer 4 is a clock that indicates standard time. On the other hand, the CPU 3 calculates the frequency (f
Considering that t-fz) itself is reversed at a repeating period of every hour as shown in Figure 3, for example, after 172 hours have passed since the external storage device started, Sampling is performed from I10 boat 2, and thereafter sampling of I10 boat 2 is performed every hour. What is sampling here?
For example, when CPU3 outputs I10 port 2,
After changing from “0” to “1”, changing from “0” to “1” for the second time.
The purpose is to monitor the change until it changes to 1. At this time, when the signal S changes for the first time, the CPU 3 refers to the time of the timer 4, writes it in the register, and furthermore, when the signal S changes for the second time, the time of the timer 4 is read. , and write this time in a register different from the one mentioned above. Furthermore, the CPU 3 has an arithmetic processing function like a normal processor, and calculates the frequency of the audio signal a from the data in the two registers mentioned above.

Furthermore, as shown in Fig. 3, the period of the signal itself changes with a constant period T, so there is usually no problem with the above-mentioned sampling, but by chance, when sampling, the frequency f1 changes. When the point is at which the frequency changes to f2, sampling is performed again.

Next, the operation of this embodiment will be explained.

First, before operating the external storage device, a frequency range is set in the CPU 3 for determining whether the audio signal waveform recorded in the external storage device is data par 0'' or 1''.

The audio signal waveform 1200Hz is data at OII, and the audio signal waveform 2400H is recorded on the tape.
If z is determined to be data ``1'' and recorded, the read audio signal waveform is between 1100Hz and 1300Hz.
If it is between 111z, data is “0”, and 2300Hz
~2500 Hz is the frequency range for determining data "1". This is because the audio signal waveform is likely to fluctuate due to external factors.

Next, when the external storage device starts operating, the audio signal a is input to the comparator 1.

As shown in FIG. 2, the comparator 1 outputs a signal when the level is 8 or higher. The CPU 3 monitors the signal output from the board 2 according to the signal output from the comparator 1. On the other hand, the CPU 3 reads the time at which the signal output from the I10 baud 7-2 changes from the timer 4, and writes it into the register. Here, the time when the signal changes is the time when the signal changes from "0" to "1".
” (the time when the signal rises, or
This is the time when the signal changes from f' I J to rOJ (the time when the signal falls). For example, the times when the signal changes are sequentially t1 + tz r tB + t4 r
--1, the time from time t0 to time t represents one period of the audio signal a being detected, and the frequency can be calculated from the time representing this period. In this embodiment, the frequency is calculated from the time from the time when the signal rises to the time when the signal rises next. Finally, 9, the CPU 3 calculates the frequency of the audio signal a being detected from the time from time t1 to time t3, which is written in a separate register and indicates the period of the audio signal a. Furthermore, the CPU 3 compares this calculated frequency with a preset frequency range, determines which frequency range it is included in, and determines whether the data in the area consisting of the audio signal a of this frequency is included. “0” or 1
For example, if the calculated frequency is 1250H
z, this is one frequency range 1100H1-130
Since it is included in 0 Hz, CPU3 is.

The data in the area composed of the audio signal a with a frequency of 1250 Hz is determined to be "Opp".

Similarly, the CPU 3 calculates the frequency from the time from the rising edge of a signal that repeats at regular intervals to the rising edge of the next signal, and determines whether this frequency is a predetermined frequency. It is determined whether the data in the area constituted by the audio signal a being detected is "0" or "1".

〔Effect of the invention〕

As described above, according to the present invention, data discrimination is not affected even if the waveform is inverted, so that data discrimination can be performed stably. Furthermore, data in an area made up of audio signals can be discriminated using only one cycle of the waveform, increasing the speed of data discrimination.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a timing chart showing the relationship between signals output from each part of the circuit according to the embodiment, and FIG. 3 is an output from an external storage device. FIG. 2 is a diagram showing an example of an audio signal waveform. 1... Comparator 2... I10 baud [・ 3... CPU 4... Timer agent Patent attorney Noriyuki Chika (and other Tamana)

Claims (1)

[Claims] A comparator that inputs an audio signal from an external storage device and outputs a signal when the audio signal is above a certain level, and a next signal from the rising (falling) of the signal output from the comparator. The time from the rise to 9 (the fall to shi) is measured, the frequency of the audio signal is calculated from that time, and it is determined whether the frequency is included in a predetermined frequency range. 1. A data discriminating device comprising discriminating means for discriminating whether data in a region where [1] is formed in an audio signal is 0'' or PA1''.