JPH0242681A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To achieve realization with a digital signal processing by making a nonlinear de-emphasis circuit similar to a nonlinear emphasis circuit in form and approximately obtaining its characteristics. CONSTITUTION:The nonlinear de-emphasis circuit 16 is constituted of a high pass filter 31 and a nonlinear limiter 33 similarly to the nonlinear emphasis circuit 12. Then, an inputted regenerative signal 15 is filtered to remove its low band component by the high pass filter 31, and is emphasized on its low level and de-emphasized on its high level by a nonlinear limiter 33. This is deducted from the original regenerative signal 15 of an input signal for the nonlinear de-emphasis circuit 16 by a subtractor 35, so as to obtain the same signal as an input signal 11 for the nonlinear emphasis circuit 12. Thus, the non-linear de-emphasis circuit 16 is made similar to the nonlinear emphasis circuit 12 in form, thus obtaining its characteristics approximately. By this method, it can be realized with the digital signal processing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device, and particularly to a magnetic recording/reproducing device having a nonlinear emphasis circuit and a nonlinear emphasis circuit.

[Conventional technology]

When recording and playing back signals on magnetic tape, high-quality recording and playback can be achieved by emphasizing high frequency components and adding the opposite characteristics during playback due to the noise characteristics of magnetic tape. realizable. However, due to constraints on the dynamic range of magnetic tape, it is necessary to weakly emphasize when the level of the input signal is high, and to strengthen it when the level of the input signal is low. This non-linear emphasis of high frequency components is called non-linear emphasis, and the reverse operation is called non-linear de-emphasis.

Here, an example of a conventional magnetic recording/reproducing device is shown in FIG. 4, FIG. 5 shows a non-linear emphasis circuit in FIG. 4, and FIG.
An example will be shown and explained.

In FIG. 4, 41 is an input signal, 42 is a non-linear emphasis circuit, 43 is a t'P signal, 44 is a magnetic tape, 45 is a reproduction signal, 46 is a non-linear de-emphasis circuit, and 47 is an output signal.

In FIG. 5, the same reference numerals as those in FIG. This is an adder that adds the input signal 41 to the output 54 of the limiter 53.

In FIG. 6, the same numbers as in FIG. 4 indicate corresponding parts, 61 is a bypass filter, 62 is the output of the high-speed filter 61, 63a is a nonlinear limiter, 64 is the output of this nonlinear limiter 63, and 65 is a regeneration signal 45
This is a subtracter that subtracts the output 64 of the nonlinear limiter 63 from .

Next, the operation will be explained.

First, the nonlinear emphasis circuit 42r shown in FIG.
The input human input signal 41 is passed through a bypass filter 51 shown in FIG. 5 to remove low frequency components, and a non-linear limiter 53 increases the degree of emphasis on low levels and weakens the degree of emphasis on high levels. . Then, by adding this to the input signal 41 in the adder 55, a record (No. N 43) with the above-mentioned non-linear emphasis applied is obtained.

Here, assuming that the transfer function of the bypass filter 51 is F and the transfer function of the nonlinear limiter 53 is G, the transfer function H of the nonlinear emphasis circuit 42 can be expressed as follows.

11=l+FφG...4...←) On the other hand, the nonlinear de-emphasis circuit 46 shown in FIG. 4 also has the bypass filter 61 and nonlinear limiter shown in FIG. It consists of 63. Then, the reproduction input to the non-linear de-emphasis circuit 46 shown in FIG.
Output 6 of non-linear limiter 63 with subtracter 65 shown in the figure
4 is subtracted, and an output signal 47 of the nonlinear emphasis circuit 46 is obtained. Further, this output signal 47 is input to a bypass filter 61, and its output 62 is input to a non-linear limiter 630, forming a feedback loop. The transfer function 11' at this time is, assuming that the transfer functions of the bypass filter 61 and the non-linear limiter 63 are the same as those of the non-linear emphasis circuit 42, H'= 1/(1+F@G)...
...■). Therefore, f(-H'=1 ・・・・・・・・・・・・
...(3), and the nonlinear emphasis circuit 42
The human input false signal and the output signal of the nonlinear de-emphasis circuit 46 match.

[Problem to be solved by the invention]

The conventional magnetic recording/reproducing device described above has a feedback loop in the nonlinear emphasis circuit, and the delay within this loop must be zero (0), so there was a problem that it was impossible to achieve with digital signal processing. .

Means for Solving Problem Cl1] The magnetic recording and reproducing apparatus of the present invention includes a non-linear effusive circuit that emphasizes high frequency components during recording according to the input level when recording and reproducing signals on a magnetic tape; In a magnetic recording/reproducing device having a non-linear de-emphasis circuit which sometimes performs the opposite operation, the reproduced signal is processed by a bypass filter and a non-linear limiter whose characteristics are inverse to those of the non-linear emphasis circuit. Non-17 to be subtracted from the reproduced signal = includes an adeninephasis circuit.

[Effect]

In the present invention, a bypass filter and a non-linear limiter whose characteristics are approximated to be the inverse characteristics of the non-linear emphasis circuit are provided, and the non-linear emphasis circuit is of the same type as the non-linear emphasis circuit, and its characteristics are approximated. demand.

〔Example〕 Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is a block diagram showing an embodiment of the magnetic recording/reproducing apparatus according to the present invention, FIG. WJ2 is a block diagram showing an embodiment of the nonlinear emphasis circuit in FIG. 1, and FIG. 3 is a block diagram showing an embodiment of the nonlinear emphasis circuit in FIG. 1. 1 is a block diagram showing an example of a switching circuit.

In FIG. 1, 11 is an input signal, 12 is a non-linear emphasis circuit that emphasizes high frequency components during recording according to the input level, 13 is a recording signal, 14H magnetic tape,
15 is a reproduction signal, 16 is a nonlinear de-emphasis circuit that performs the opposite operation to that of the nonlinear emphasis circuit 12 during reproduction, and 1T is an output signal.

In FIG. 2, the same reference numerals as in FIG.
is the output of the non-linear limiter 23, and 25 is an adder that adds the input signal 1.1 to the output 24 of the non-linear limiter 23.

In FIG. 3, the same numbers as in FIG. 1 indicate corresponding parts, 31 is a bypass filter, 32 is the output of this -pass filter 31, 33 is a non-linear limiter, 34 is an output of this non-linear limiter 33, and 35 is a bypass filter. This is a subtracter that subtracts the output 34 of this non-linear limiter 33 from the reproduced signal 15.

Here, the bypass filter 31 and the nonlinear limiter 3
3 is an Ibus filter and a non-linear limiter whose characteristics are approximated to be the inverse characteristics of the non-linear emphasis circuit.

The circuit shown in FIG. 3 passes the reproduced signal 15 to the bypass filter 31. It constitutes a non-linear de-emphasis circuit that subtracts from the original reproduced signal 15 after processing by the non-linear limiter 33.

Next, the operation of the embodiment shown in FIGS. 1 to 3 will be explained.

First, the input signal 11 input to the non-linear emphasis circuit 12 shown in FIG. 1 has its low frequency components removed by the bypass filter 21 shown in FIG. Decrease level emphasis. By adding this to the input signal 11 in the adder 25, a non-linear emphasis characteristic is added to obtain the companion recording signal 13. Here, if the transfer function of the bypass filter 21 is F and the transfer function of the nonlinear limiter 23 is G, then the transfer function H of the nonlinear emphasis circuit 12 is )(=1.+F@G... ...
...(1).

Next, the nonlinear de-emphasis circuit 1 shown in the first factor
Similarly to the non-linear emphasis circuit 12, 6 is a bypass filter 31 and a non-linear limiter 33 shown in FIG.
Consists of. The reproduced signal 15 input to the nonlinear de-emphasis circuit 16 shown in FIG.
A bypass filter 31 shown in the figure removes low frequency components, and a non-linear limiter 33 strongly emphasizes low levels and weakens high levels. Subtractor 3
5, the same signal as the input signal 11 of the nonlinear de-emphasis circuit 12 is obtained by subtracting it from the original reproduced signal 15 which is the input signal of the non-linear de-emphasis circuit 16. If the transfer function of the bypass filter 31 at this time is G', the transfer function of the biononlinear limiter 33 is G', then the transfer function H' of the nonlinear de-emphasis circuit 16 is H'-1-F'G'... ...Song... 0
). Therefore, according to equations (4) and (5) above, the integrated characteristics of the non-linear emphasis circuit 12 and the non-linear de-emphasis circuit 16 are as follows:=HII'=1-F'G'+FG-FF'GG'
......(6).

Here, −F'G' + FG + F'F'GG'”:'
By choosing F/ and a/ so that 0 ・---------・・−・−(7), Kzl ・
・・・・・・・・・・・・・・・・・・・・・
...(8) can be done.

〔Effect of the invention〕

As explained above, by making the non-linear de-emphasis circuit of the present invention in the same format as the non-linear emphasis circuit and approximating its characteristics, it is possible to create a configuration without a feedback loop. There are effects that the device can achieve through processing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the magnetic recording/reproducing apparatus according to the present invention, FIG. 2 is a block diagram showing an embodiment of the nonlinear emphasis circuit in FIG. 1, and FIG. 1 is a circuit diagram showing an example of a non-linear emphasis circuit in M4; FIG. 4 is a block diagram showing an example of a conventional magnetic recording/reproducing device; FIG. 5 is a block diagram showing an example of a non-linear emphasis circuit in the M4 diagram. , FIG. 6 is a block diagram showing an example of the non-linear de-emphasis circuit in FIG. 4. 11... Input signal, 12... Non-linear emphasis circuit, 13. 〇-Record No. M, No. 14・ψ・Magnetic tape, 15φ meeting--playback signal, 16・War pot・nonlinear de-emphasis circuit, 11m...output signal, 21φ
...--I pass filter, 23--O non-linear limiter, 25--cloudy adder, 31--bypass filter, 33-@φ non-linear limiter, 35--fist number subtracter.

Claims (1)

[Claims] When recording and reproducing signals on magnetic tape, magnetic recording has a nonlinear emphasis circuit that emphasizes high frequency components according to the input level during recording, and a nonlinear de-emphasis circuit that performs the opposite operation during playback. The playback device includes a high-pass filter whose characteristics are opposite to those of the nonlinear emphasis circuit, and a nonlinear de-emphasis circuit that subtracts the playback signal from the original playback signal after processing with a nonlinear limiter. A magnetic recording/reproducing device characterized by: