JPS585478B2 - Yomitori Cairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reading circuit for a storage device or the like, which is capable of detecting a signal to be detected from an input signal on which low frequency noise is superimposed.

In the reading circuit of a storage device, it is necessary to prevent signals from being read incorrectly due to noise.

If the amplitude of the noise is smaller than the amplitude of the signal, the signal can be detected simply by an amplitude discrimination circuit, but if the amplitude of the noise is larger than the amplitude of the signal and the frequency of the noise is lower than the frequency of the signal, a DC regeneration circuit is used. FIG. 1 shows a block diagram of a reading circuit according to the conventional method.

In the figure, 1 is an input terminal, 2 is a DC regeneration circuit for removing low frequencies, 3 is an amplitude discrimination circuit, 4 is a wide strobe signal input terminal for controlling the DC reproduction circuit, and 5 is an amplitude discrimination circuit. This is the input terminal for the narrow strobe signal given to the .

FIG. 2 is an operational waveform diagram for explaining the operation shown in FIG. 1, and the operation shown in FIG. 1 will be explained in detail using this diagram.

Although a is a signal waveform with an amplitude of Vs to be detected, a waveform on which low frequency noise is superimposed is added to the input terminal 1 as shown by b.

Here, the solid line part and the broken line part of the waveform are where the signal is, respectively.
This shows the case without (the following waveforms are similar).

The wide strobe C is applied from the rising position of the signal to the time position sufficiently containing the signal, and the output of the DC regeneration circuit 2 has a waveform d.

The narrow strobe of e has the signal-to-noise ratio S/N in the waveform of d.
Apply to the device that produces the maximum.

The noise level VN when applying this narrow strobe is the change value of the noise waveform from the rising value of the wide strobe C to the narrow strobe e.

Therefore, the discrimination level VT1 of the amplitude discrimination circuit 3 is set to VN and VN.
If the level is set between +Vs, an output of f can be obtained.

However, the noise level VN is usually not a constant value, so if the fluctuation level width is larger than the signal amplitude Vs, it is impossible to distinguish between the noise and the signal unless the discrimination level VT1 is varied depending on the noise level. There is a drawback.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the conventional circuits described above and provide a reading circuit with a high signal-to-noise ratio.

FIG. 3 is a block diagram of a reading circuit which is an embodiment of the present invention.

In the figure, the same symbols as in Figure 1 indicate the same parts, 7 is a delay element with a delay time of time Tw from the signal rise time to the maximum value, and 8 takes the differential between the input signal and the delay string output g. It is a differential amplifier circuit.

FIG. 4 is a waveform diagram for explaining FIG. 3.

The operation shown in FIG. 3 will be explained in detail using FIG. 4.

The same symbols as in FIG. 3 indicate waveforms of the same parts.

g is the output waveform of the delay element 7, which lags behind the waveform of the input signal S by Tw.

h is the output waveform of the differential amplifier circuit 8, and by taking the differential between the input signal and the delayed signal g, the noise level is attenuated and the signal level remains unchanged.

If the DC regeneration circuit 2 is operated with the output of the differential amplifier circuit 8 indicated by h, the noise level VN will be almost 0, that is, the value immediately before the signal to be read once through the DC regeneration circuit 2 will be 0V.
can be set to improve the S/N ratio.

If the discrimination level VT2 of the amplitude discrimination circuit 3 is set to approximately half the signal level, the signal can be detected stably.

Note that the output of the amplitude discrimination circuit 3 is the same as that shown in FIG. 1 and is therefore omitted.

Furthermore, the signal-to-noise ratio can be improved by changing the timing of the wide strobe C shown in FIG.

In other words, by setting the rising position of the wide strobe C to the time position of the maximum value, rather than the rising time position of the signal, as shown in FIG. It can be twice as much as vs.
At this time, the discrimination level VT3 can be set to approximately vs, and since the noise level VN does not increase, it is possible to further improve the signal-to-noise ratio S/N.

As described above, according to the present invention, it is possible to realize a reading circuit that stably detects a signal to be detected from an input signal on which noise of large amplitude and low frequency is superimposed.

The present invention is particularly suitable for application to a reading system of a magnetic bubble storage device whose input signal has the above characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional reading circuit, FIG. 2 is a waveform diagram for explaining FIG. 1, FIG. 3 is a block diagram showing an embodiment of the reading circuit according to the present invention, and FIGS. FIG. 5 is a waveform diagram for explaining FIG. 3. Explanation of symbols, 1...Input terminal, 2...DC regeneration circuit, 3
...Amplitude discrimination circuit, 4...Wide strobe input terminal,
5...Narrow strobe input terminal, 6...Output terminal, 7
...Delay element, 8...Differential amplifier circuit.

Claims (1)

[Claims] 1 A circuit that reads a signal to be detected from an input signal containing noise with a frequency larger than the detection level of the signal to be detected and whose amplitude is larger than the detection level of the signal to be detected, the circuit reading the signal to be detected from the rising position of the signal to be detected to the maximum value or from the falling position of the signal to be detected. a delay element that delays an input signal by a time up to a minimum value; a differential amplifier circuit that takes a difference between an output signal of the delay element and the input signal;
and a DC regeneration circuit that receives the output of the differential amplifier circuit, and converts the value immediately before the signal read by the DC regeneration circuit to 0V.
A reading circuit characterized in that it is configured to set.