JPS6012708B2 - How to reproduce phase code recording signals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for reproducing signals magnetically recorded using a phase code method (PE method).

As is well known, when reproducing data signals magnetically recorded using the PE method, in addition to magnetization reversal of the data signals, fizz
Since a magnetization reversal signal called a phasebit, which is not a data signal, is reproduced, it is necessary to mask this magnetization reversal signal, which is not a regular data signal.

FIG. 1A shows an example of a data signal magnetically recorded using the PE method, in which A, B, and C are reproduced as magnetization reversal signals that are not regular data signals.
Therefore, as a method of masking magnetization reversal signals that are not regular data signals, the most principled method is to use a monostable multipipe layer with a time constant corresponding to 3'4 of the reproduction period of the data signal. proposed as a method.
However, this method is not widely used because if a data bit drops out, there is a possibility that the phase bit will be regenerated as a data bit. On the other hand, tape drives, which are widely used as computer peripherals, use a variable frequency oscillator to control the variable frequency oscillator according to the frequency of the data signal being reproduced, adjust the phase, and reproduce only regular data signals. The method is common.

However, in this method, it is necessary to run the magnetic tape at a constant speed with high precision, and therefore the tape drive mechanism is complicated and expensive.

A similar problem occurs with so-called magnetic card readers (magnetic card readers), which are plastic cards with magnetic tape attached that are commonly used to operate online systems, cash dispensers, etc. that have been adopted by banks in recent years. The same can be said about leaders).

That is, when data signals are recorded on a magnetic card using the above-mentioned PE method, it becomes necessary to run the magnetic card at a strictly constant speed, which makes the drive mechanism of the magnetic card reader complicated and expensive. In addition, in the conventional method, discussion cannot be started until the magnetic tape or magnetic card reaches a predetermined speed, which increases the discussion time. This required a complex control circuit.

This invention was made in order to eliminate the above-mentioned drawbacks, and it is possible to accurately read data signals recorded on magnetic media such as magnetic tapes and magnetic cards even if they are not run at a constant speed. This invention provides a method for reproducing signals magnetically recorded using a code method. The method of the present invention will be explained in detail below with reference to the drawings.

The present applicant previously proposed a magnetic reading head that can accurately read F and bait signals corresponding to 0 and 1 signals magnetically recorded using a frequency modulation method even if speed changes occur in the running of a magnetic card. did.

As described in Japanese Unexamined Patent Application Publication No. 51-99007, this magnetic reading head has a magnetic sensor at a distance shorter than the wavelength of the F signal and longer than the wavelength of the dense signal from the center of one magnetic detection section. The center of the magnetic detection section is located here. In this way, if two magnetic detectors are separated by a specific distance and both detectors exchange signals, then the same The output signal of one comes out from the other detector with a delay. Therefore, even if there are fluctuations in the running speed of the magnetic card, stable and reliable discussions can be carried out. For details, please refer to the present applicant's Japanese Patent Application No. 13644/1983 titled ``Magnetic Control Head''. The present invention utilizes the above-described magnetic read head to accurately read data signals recorded in the PE method without requiring constant speed of the magnetic medium.

As is evident from the waveform shown in FIG.
For a distance of 1 wavelength where signals and 0 signals alternate, the distance where 1 signals or 0 signals continue is necessarily 1/2 wavelength, and therefore the frequency of the latter is twice the frequency of the former.

Therefore, the waveform of FIG. 1a can be considered to be in the form of a signal F. Therefore, a magnetic reading head having the above configuration can be used. Now, if the distance between the two magnetic detection parts of this magnetic reading head is set to 3/4 skin length of the data signal, and if the read output signal from one detection part has the waveform shown in Figure 1a, then the other As shown in FIG. 1b, an output signal delayed by 3/4 skin length is obtained from the detection section. Both of these output signals are supplied to a signal processing circuit shown in FIG. 2, for example. First, the output signal of FIG.
．． In addition to both the series circuit of the inverter 12 and the series circuit of the differentiating circuit D2 and the inverter 13, the outputs of both series circuits are connected to the NOR circuit NO. and the timing terminals T of the corresponding D-type flip-flops FF and FF2, respectively.

NOR circuit NO. The output signal becomes a negative pulse signal train corresponding to each rise and fall of the waveform of the output signal a, as shown in FIG. 1c. Similarly, the output signal of FIG. supply to. The output signal of the NOR circuit N02 becomes a negative pulse signal train corresponding to each rise and fall of the waveform of the output signal b, as shown in FIG. 1d. First NOR circuit NO. The output of the JK flip-flop FF3 is supplied to the clock terminal CP of the JK flip-flop FF3, and is also supplied via the inverter 17 to one input terminal of the NAND circuit NA. Further, the output of the second NOR circuit N02 is a D-type flip-flop FF,
and is supplied to each reset terminal R of FF2 and JK flip-flop FF3. Therefore, these flip-flops FF, -FF3 are cleared by each rising and falling edge of the waveform of the output signal b. JK Fritzpf. 1 output terminal of FF3 is NAND circuit NA,
is connected to the other input terminal of the NAND circuit NA,
The output of is applied to a monostable multipipulator MM. Therefore, the initial condition of JK flip-flop FF3 is set to 0.
Then, this flip-flop FF3 becomes 1 at the first pulse of the pulse signal c in FIG. 1, becomes 0 at the second pulse, and repeats this state sequentially thereafter. However, in reality, it is cleared by the pulse signal shown in FIG. If the rising and falling edges of the pulse are continuous, the pulse becomes 0 by the second pulse. Therefore, the NAND circuit NA opens only when the magnetization of the normal data signal is reversed, and does not open depending on the phase bit.
FIG. 1e shows the output signal waveform of this NAND circuit NA. As mentioned above, since the output signal of the NAND circuit NA is applied to the monostable multipipulator MM, this monostable multi/vibrator MM is driven by the pulse shown in FIG. 1e, and its output is A positive clock pulse signal of the same type as that of FIG. 1e is generated at the connected clock signal terminal Tc. monostable multipipulator MM,
The outputs of the second and third NAND circuits NA2 and N
are also connected to one input terminal of each. The other input terminals of these NAND circuits NA2 and N are connected to D-type flip-flops FF and FF2, respectively.
The output terminal is connected to the second NAND circuit NA2.
The output of the third NAND circuit NA3 is connected to the timing terminal T of the D-type flip-flop FF4 via the inverter 18, and the output of the third NAND circuit NA3 is connected to the reset terminal R of the D-type flip-flop FF4. Therefore, the second NA
The ND circuit N is opened by a rising pulse corresponding to a data signal of 1 in the output signal of FIG. 1a, and the third NAND circuit NA2 is opened by a falling pulse corresponding to a data signal of 0 of the output signal of FIG. Therefore, a data signal as shown in FIG. 1f is generated at one output terminal of the D-type flip-flop FF4. As described above, according to the method of the present invention, it is possible to reliably identify data signals magnetically recorded by the PE method, that is, 1 and 0 signals, using the rise and fall of the waveform of the output signal from the read magnetic head. Because of this, there is no need to run the magnetic medium at a constant speed with high precision, and therefore the drive mechanism for the magnetic medium can be significantly simplified, and furthermore, it brings about great benefits such as shortening the negotiation time and lowering the cost.

Furthermore, since speed-independent data output can be obtained without self-clocking, data can be transmitted at any speed, for example, in data transmission between terminal devices. Furthermore, by making the output signals a and b correspond to each other, it is possible to detect errors such as when one is being read but the other is not being read. In addition,
It goes without saying that the processing circuitry described above is merely for illustrative purposes and that various modifications may be made as desired.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram of output signals of various parts for explaining the present invention, and FIG. 2 is a schematic configuration diagram showing an example of a signal processing circuit suitable for carrying out the present invention. Explanations of the symbols representing the main parts of the figure are as follows.
1, ~L: Inverter, D, ~D4: Differential circuit, NO.
~N02: NOR circuit, NA, ~NA3: NAND circuit, FF, ~FF4: flip-flop, MM,: monostable multipipulator. Figure 1 Figure 2

Claims (1)

[Claims] 1. In reproducing a data signal magnetically recorded using the phase code method, a second magnetic detecting section is placed at a distance shorter than one wavelength of the data signal and longer than half a wavelength of the first magnetic detecting section from the center of the first magnetic detecting section. reading the data signal using a centrally located magnetic read head;
forming first and second pulse signals corresponding to each rise and fall of the waveform of the output signal from the detection unit;
The first pulse signal drives the bistable circuit, the second pulse signal clears the bistable circuit, and the output signal of the bistable circuit and the inverted signal of the first pulse signal are combined into an AND circuit. A clock pulse signal is obtained from the output signal of the circuit, and a data signal corresponding to the first pulse signal from the first detection section is generated using the output signal of the AND circuit or the clock pulse signal. A method for reproducing a signal magnetically recorded using a phase code method, characterized in that the signal is generated using a phase code method.