JPS5911515A - Data demodulating system - Google Patents

Abstract

PURPOSE:To attain correct demodulation even with unstable front part of data, by detecting the demodulation of a bit signal of other sign before a demodulator demodulates a bit signal of a sign for a specified number of bits for resetting the demodulator. CONSTITUTION:A magnetic head 11 is broughto into contact with a magnetic medium such as magnetic bank book or the like at data reading, is moved relatively, reads out data from the magnetic recording medium and inputs the data to a demodulator 12. The demodulator 12 measures the interval of front bits for changing the time width of a data discriminating pulse, masks the data of the next bits and discriminates whether it is 1 or 0. The variable mask system is operated correctly even if the readout speed of data is changed and it is effective to a manual system or the like where the readout speed of data is not constant. A readout data RDD and a clock RCP are outputted via inverters I 1, I 2, and the readout data RDD from the inverter I 1 is on a high level when the data is 0 and on a low leel when 1.

Description

[Detailed description of the invention]

The present invention relates to a data demodulation method for demodulating data that has not been recorded on a magnetic recording medium such as magnetically transmitted water. The data recorded using the F2F method on a magnetic recording medium such as a magnetic passbook also includes a preamble signal before the actual data.1. This signal consists of multiple bits of the same code consecutively (.) Here, the FZF method is one of the FM (low frequency?A) methods, and the data on the magnetic recording medium is transmitted between bit intervals. If the magnetic reversal is 1, it is 'l'', and if there is no magnetic reversal, it is ``0''.The data on this magnetic hC recording medium is read by the magnetic head and demodulated by the demodulator at Jl. When the magnetic recording medium is first brought into contact with the magnetic recording medium, the
114 The starting position of the data may not be constant, and the first part of the data may be unstable and not guaranteed. Therefore, a method is used to omit the first part of the data. However, with this method, the length of the unspecified part of the data is fixed (・な(・・), so it is not possible to set the number of data. In some cases, the actual data must be transmitted through the Omino L-L.In the history, the preamble signal is reduced in the Ominoto, so when performing data recovery including the preamble signal, [fl , it is disadvantageous.The signal of the 7-point river may also be seen as floating data, and in this case, it is not desirable to omit the first part of the data, and it is easy to convert it into a second-by-second data format. An object of the present invention is to improve the above-mentioned drawbacks and provide a data demodulation method that can correctly demodulate data even if the front part of the data is unstable. The present invention will be explained by giving a practical example with reference to the drawings. Figure 3.1 shows an example of the present invention, and Figures 3.2 are its timing diagrams. The magnetic head 11 is connected to data. When removing wood, it comes into contact with a magnetic recording medium such as a magnetic continuous book and moves relatively 1, and the data is extracted from the recording medium and input to the demodulator 12.This magnetic recording medium records data, for example, in F2F. This data has a preamble signal l'ifJ than the actual data (it has a synchronization bit signal before the start mark).The preamble signal has multiple bits "Oo" at the front, This 50" differs depending on the standard, but for example it is 10 to 30 bits. The demodulator 12 generates clock and data discrimination pulses from the input signal from the magnetic head 1, and uses the data discrimination pulses to convert the input signal to "15". At this time, the relative speed (data read speed) between the magnetic head 11 and the magnetic recording medium is detected by the upper t-picron clock, and the data discrimination is performed according to this speed. The time width of the pulse is varied.The demodulator 2 measures the previous bit's inotar pulse, changes the time width of the pulse for determining the °C data, and uses the pulse for determining the data to output the next bit of data f.
The well-known variable mask method uses a mask to determine whether it is "]" or "0".This variable mask method operates correctly even when the data reading speed changes, and especially when the data read speed is It is effective in manual methods where the magnetic head and the magnetic 6-pin recording medium are moved relatively over a distance of 1,000 m.
CP is output via inverters I, I2, but m6 output data RDD from inverter 11 is
The level becomes high at 11", and the level becomes low at 11".The data recorded here by F2F is initially set at 50".
' is followed by multiple bits, followed by 111, followed by actual data. When data demodulation has not yet started and the first clock is output from the demodulator 12, this clock is counted by the counter CNT and its "l" output terminal becomes high level. At this time, the r2J and r4J output terminals of the color/liquid CNT remain at a low level. Therefore, diode D1
or off and diode D2. D is turned off, and the output of inverter 6 becomes high level. On the other hand, the route output data RDD of the demodulator 12 is at the level of Mr.
Nando l! The output of Ill path N1 becomes high level. At this point, the demodulation start signal is at a high level, and the output of the crow/do circuit N2 becomes the 1 degree level, and the crow/do circuit N2 is at a high level.
At the same time that T is not reset, the output of inverter 4 becomes high level and the demodulator 12 is also reset. The clock RCPz from the demodulator] 2 goes to CNT, but the signal goes to "l" as it goes. [, zJ, r4J output terminals go high in binary. Therefore, the counter CNT is r until the count number reaches 6.
One or two of the l, j, r2j, r4j output terminals become low level, and the output of inverter 6 remains high level. At this time, the read data RDD of the demodulator 12 remains at a low level, and the state of Fang 1 does not change.
, all the r4J output terminals are at Akane level, and the diode Di
, D2. All D3 are turned off and the power supply voltage is applied to the -C inverter 6 via the resistor R1. Therefore, the output of inverter I3 becomes low level, and the
The CNT stops counting because the high-pull terminal E becomes low level, and the demodulator j2 is also reset 3j.
q disappears. Now the count number of C/CNT is 7] During f-cutting, the demodulator 12 mistakenly outputs 11 and the vinegar

[Protrusion data R
When DD becomes a high level, the output of the nut circuit N1 becomes a low level and the output of the F/F circuit N2 becomes a control level, setting the counter CNT and the substitute regulator. Therefore, when the demodulator 12 is reset, the data discrimination pulse disappears, the -C read data RDD becomes low level, and data demodulation continues again. The counter CNT also counts the clock RCP from the demodulator]2. Thereafter, the count number of the color/liquid CNT becomes 7, the color/liquid CNT no longer counts 11 as described above, and the demodulator 12 is reset to 1. In this embodiment, the first 6 bits of data are checked and if W]' is mistakenly detected, the demodulator 12 is reset, but the number of bits to be checked in the data can be set arbitrarily with reference to the Cheetah man node. I can do it. As described above, according to the present invention, the demodulator detects that a bit signal of a different code has been demodulated before demodulating a bit signal of the same code by a specified number of bits (n'?J), and resets the demodulator. Even if the front part is unstable, it can be demodulated correctly, and at the right time, the data can be demodulated to the front part of the front part. Furthermore, the above detection can be performed reliably using a dental method.

[Brief explanation of drawings]

Figure 3.1 is a block diagram showing an embodiment of the present invention, J'
FIG. 2 is a timing chart of the same embodiment. 12... Demodulator, CNT... Color/Re, ■1 to ■4
...Innovata, N1. N2...Nano F circuit, D1
~D3... Teriode, R1... Resistor.

Claims (1)

[Claims] In a data demodulation method in which a multiple bit signal of the same code at the front of data that has not been recorded on a magnetic recording medium is demodulated by measuring the inoter pulse of the previous bit with a demodulator, the demodulator A take demodulation method characterized in that the demodulation of bits of another code is detected before demodulating the bit signal station of the standard code by a specified number of bits, and the demodulator is set to J5.