JPS5843809B2 - Data recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an F
SX (frequency 5hift key
ing) In a recording system, the present invention relates to a recording method that enables accurate data reproduction.

When the conventional FSK method is applied to a recording system having a recording medium whose data recording/reproducing speed fluctuates, as shown in FIG. Even if it is recorded, the receiver 3 on the reading side has (1
+△), f (where △ is an error component due to speed fluctuation) is read in, which has the disadvantage that the information is incorrect.

For example, in a magnetic tape device with two recording media, when an FSK signal is used to identify the start and end of audio information for every l unit of audio information on the track for recording control signals, the accuracy of the tape drive mechanism is low. Therefore, when the write or read speed changes or when a control signal is detected by continuous feeding, a frequency different from the frequency of the original control signal may be detected, resulting in malfunction.

SUMMARY OF THE INVENTION An object of the present invention is to provide an FSK signal recording method that eliminates the above-described drawbacks of the prior art and makes it possible to accurately obtain the original signal.

A feature of the present invention is that a reference signal is superimposed on a signal to be recorded and written onto a recording medium, and when reading, the original signal and the reference signal are separated and compared to detect the original signal. It's because I did it.

FIG. 2 is a block diagram showing one embodiment of the present invention.

On the transmitting side, in addition to the signal source 1 having the frequency f1, there is also a signal source 1 having the frequency f1.

A reference signal generator 4 is provided, and the outputs of both are added by an analog adder 5.

Therefore, the signals written to the recording medium 2 include f, ,
It has f, 02 frequency components.

When the frequency is multiplied by (1+Δ) during reading, the frequency of the original signal becomes (1+Δ)f, and the frequency of the reference signal becomes (1+Δ)fo.

Here, a frequency discriminator shown in 6 separates a signal with a frequency of (1+△)fl from a signal with a frequency of (1+△)fo, and a frequency comparator shown in 7 separates a signal with a frequency of (1+△)fl and a signal with a frequency of (1+△). ) foO ratio, it becomes f1/f,
The variation Δ is canceled and the original signal can be obtained accurately.

To explain more specifically, for example, as shown in FIG. 3, information Di such as audio is recorded sequentially in sections on a magnetic tape, and a signal with a frequency f1m indicating the beginning of the information and the information are on the control signal track. If a signal with frequency f12 indicating the end of fll? is recorded, then fll? f different from the frequency of f1□.

A reference signal with a frequency of is superimposed on these signals and written to the control signal track.

In this case, fo is 0.5KHz, fll is IKHz
, f12 is 2KHz, the normal read speed is about 10 times the write speed, and the read speed is 10 times higher than the write speed due to low precision or inertia of the tape drive mechanism.
If it is decided to vary by a factor of 1 to 10, the signal of f1□tfl□ is detected by a circuit configured as shown in FIG.

That is, the frequency discriminator 6 is composed of bandpass filters F1 to F6, and each bandpass filter F1 to F6 has a frequency of 0.3
75~0.75.0.75~1.5.1.5~3.3~
6.6 to 12. When a signal of 12 to 24 KHz is read out, a signal of logic level "■" is output, and in other cases, I
IO” is output.

Comparator 7 includes AND gates A1 to A8 and OR gate OR1
, OR2.

AND gates A1 to A4 are the Fl of bandpass filters, respectively.
and F2, F2 and F3, F3 and F4, and F4 and F5, and AND gates A5 to A5 respectively
and F3, F2 and F4, F3 and F5, and F4 and F6 are connected to AND gates A1 to A.
Each output of AND gates A5 to A8 is connected to be inputted to OR gate OR1, and each output of AND gates A5 to A8 is inputted to OR gate OR2.

With this configuration, even if the reading speed changes during reading, f, , /f will always be 2, and
And when the signal of f□1 is read out, f.

Since the signals of AND gates A1 to A are also read out at the same time,
Output ゛°1'' is obtained in either of 4, OR gate OR
The control signal read out from the output terminal 8 through 1 is the signal ftt indicating the beginning of information.

Also, when the f12 signal is read, f12/fo
Since is always 4, an output +10'n is obtained from any of the AND gates A5 to A8, and the control signal read from the output terminal 9 through the OR gate OR2 is the signal f12 indicating the end of information. is output.

Furthermore, it is easily understood from the above description that even if the writing speed itself varies somewhat, it is possible to detect the fil t f12 signal during reading.

The present invention can be applied not only to magnetic tapes as recording media, but also to magnetic disks or magnetic drums whose recording and reproducing speeds vary.

Further, as the signal to be detected, not only the above-mentioned control signal but also a signal for displaying a character may be employed.

As explained above, in a recording system using a recording medium whose recording/reproducing speed fluctuates, the present invention records a reference signal superimposed on the original signal, and upon reproduction, the original signal and the reference signal are combined. Since the original information is obtained by separating the signals and detecting the ratio of the respective frequencies, there is an effect that the information is accurately transmitted.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional FSK system applied to a recording system where the recording/reproduction speed fluctuates, Fig. 2 is a block diagram showing the basic concept of the present invention, and Fig. 3 is an example of a recording system according to the present invention. FIG. 4 is a circuit diagram showing an example of a readout system according to the present invention used for detecting the signal in FIG. 3. 1... Signal source, 2... Recording medium, 4.
...Reference signal generator, 6"...Frequency discriminator, 7...Frequency comparator, A1 to A8...
...And gate, F1 to F6...Band filter, OR1, OR2...Or gate.

Claims (1)

[Claims] 1 F with a recording medium whose data recording and playback speed fluctuates
When the SK recording button is pressed, a reference signal generator is provided in addition to the signal source on the data writing side, and the reference signal is superimposed on the original signal to be recorded and written to the recording medium, and on the reading side, the source signal that has undergone frequency fluctuation is A data recording method characterized by obtaining the original information by separating the signal from the reference signal and detecting the ratio of their respective frequencies.