JPS6129406A - Magnetic recorder - Google Patents

Abstract

PURPOSE:To prevent the excessive reduction of the high band of a wide-band signal by providing an equalizer circuit at the post stage of an FM modulator for the wide-band signal of a magnetic recorder which applies FM modulation to record the wide-band signal to a magnetic recording medium whose adverse wavelength characteristics has a single peak. CONSTITUTION:The video signal given from an input terminal 3 of a recording system 1 undergoes FM modulation through an amplifier 4 and an FM modulator 5 and is supplied to a recording amplifier 6 serving as an equalizer circuit. Then the low band of the video signal is emphasized and also the areas exceeding the highest frequency fp is flattened. Then an input is applied to a magnetic head 7 for execution of recording to a magnetic tape 8. While in a reproduction system 2 the high bands exceeding the frequency fp are emphasized by an equalizer circuit 11 via a reproduction amplifier 10 for the reproduced FM modulation video signal given from a magnetic head 9. While the low bands of the video signal is flattened. Such video signal is supplied to an output terminal 14 via an FM demodulator 12 and an amplifier 13. Therefore, the excessive deterioration is prevented for the high band of a reproduced video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a magnetic recording medium in which the reverse wavelength characteristic exhibits a single peak.
The present invention relates to a magnetic recording device that modulates and records a wideband signal such as a video signal using an FM modulator.

BACKGROUND ART AND PROBLEMS The reverse wavelength (1/λ) characteristic of conventional magnetic tapes (cassette tapes) such as gamma-hematite and metal tapes is
As shown in Figure 1 (1/λ and level are expressed logarithmically), it exhibits a nearly monotonically decreasing characteristic in the direction of increasing 1/λ, so it is shown in Figure 1O (only level is expressed logarithmically). An FM modulated video signal having a frequency (fl spectrum) (fc: carrier frequency, fc+fp: upper sideband frequency.

When EC-fp: lower sideband frequency, fp: highest frequency of the video signal) is recorded on such a magnetic tape using a rotating magnetic head and played back, the frequency characteristics of the playback output are as shown in Figure 11 (level only). As shown in (logarithmically expressed), the level of the lower sideband is enhanced and the level of the upper sideband is decreased, but the decrease in the level of the upper sideband is compensated for by the increase in the level of the lower sideband, so during playback, the FM recovery There is no risk that the high frequency range of the video signal obtained by opening the gate will deteriorate.

However, the reverse wavelength characteristics of thin film magnetic recording media are
As shown in the figure (1/λ and level are expressed in logarithms), it exhibits a single peak with a peak in the short wavelength region. When recording horizontally or vertically on a medium and trying to reproduce it, the reproduction frequency characteristic is f = v/λ (
However, if we consider the relational expression (■ is the relative velocity between the belly button and the tape), then Figure 12 (only the level is expressed in logarithm)
To.

As shown in Figure 13 (only the level is expressed logarithmically), the levels of the upper and lower sidebands have decreased significantly, so the video signal obtained by FM demodulation during playback is The drawback was that the high range was degraded.

Purpose of the Invention In view of the above, the present invention provides a magnetic recording device that modulates and records a wideband signal using an FM modulator on a magnetic recording medium with a monomodal reverse wavelength characteristic. The present invention attempts to propose a magnetic recording device in which there is no risk that the high frequency range of a wideband signal generated by the magnetic recording device will be significantly degraded.

Summary of the Invention The present invention provides a magnetic recording device that modulates and records a broadband signal using an FM modulator on a magnetic recording medium with a monomodal reverse wavelength characteristic. This is characterized in that an equalizer circuit that enhances the low frequency range of the FM modulator is provided at a subsequent stage of the FM modulator.

According to the present invention, in a magnetic recording device in which a broadband signal is modulated by an FM modulator and recorded on a magnetic recording medium exhibiting a monomodal reverse wavelength characteristic, the broadband signal demodulated by FM during reproduction is It is possible to obtain a magnetic recording device in which there is no possibility that the high frequency range of the signal will deteriorate too much.

Embodiment An example of a magnetic recording/reproducing apparatus to which the present invention is applied will be described below with reference to FIG. In FIG. 1, (1) is a recording system, and (2) is a reproduction system. In the recording system (1),
The video signal from the input terminal (3) is supplied to the FM modulator (5) via the amplifier (4), and the obtained FM modulated video signal is supplied to the recording amplifier (6) as an equalizer circuit. The output is supplied to the magnetic head (7) and the magnetic tape (
8).

As shown in Fig. 2 (only the level is expressed logarithmically), the recording amplifier (6) enhances the low range below the highest frequency rp of the video signal with a slope of, for example, -6 dB/oct, so as to exceed the highest frequency rp. The high range has a flat characteristic.

In the reproduction system (2), the FM modulated video signal reproduced from the magnetic tape (8) by the magnetic head (9) is supplied to the equalizer circuit (11) via the reproduction amplifier a.

The output of the equalizer circuit (11) is supplied to an FM demodulator (12) for demodulation, and the resulting video signal is supplied to an output terminal (14) via an amplifier (13).

As shown in FIG. 3 (only the level is expressed logarithmically), the equalizer circuit (11) enhances, for example, the high frequency range above the highest frequency fp of the video signal with a gradient of 6 dB10 ct, and The area has the characteristic of being flat.

In the recording system (1), depending on the characteristics of the magnetic tape (8), the level may be increased as the frequency decreases as shown in Figure 4 (only the level is expressed logarithmically) before the amplifier (6). It is also possible to insert other equalizer circuits with frequency characteristics that gradually improve.

In this way, the frequency spectrum of the reproduced FM modulated video signal shows a curve (16) shown by the solid line in FIG. , the both-side band waves become flat as a whole, as shown by the broken line curve (17). In this way, there is no possibility that the high frequency range of the reproduced video signal obtained by recording the video signal after FM conversion and demodulating the reproduced signal will deteriorate too much.

It is also possible to not provide the equalizer circuit (11) in the reproduction system (2), but in that case, the dashed line curve (1
As shown in 8), some reduction in high frequencies is observed.

Next, the reproduction equalizer circuit (1) corresponding to the amplifier (6)
Another specific circuit example of 1) will be explained with reference to FIG. This is a type of cosine equalization layer, and is characterized by linear phase characteristics. (20) is a signal current source for the FM modulated video signal, which is connected to a delay circuit (delay amount) that matches the sending end and opens the receiving end through a series circuit of a variable resistor (21) and a variable inductor (22) for matching. td) (
23) and the respective input sides of the buffer circuit (26). The output of the delay circuit (23) is supplied to a combiner (amplifier) (25) through a buffer circuit (24). Furthermore, the output of the buffer circuit (26) is supplied to the combiner (25) through a variable attenuator (with an attenuation factor of K) (27), and is added to the output of the buffer circuit (24), resulting in the added output. is output to the output terminal (28).

Signal current of signal current source (20) (%) 5in2π
ft (where f: frequency, t: time), the input signal to the delay circuit (23) and buffer circuit (26) is (V2) sln 2yrf (t-2td) +
(!4) The output signal of the sin 2πft buffer circuit (24) is expressed as (%) sin 2πf (t-td) variable attenuator (2
The output signal of 7) is K((!4)sin 2 πft+ (!4)sin
2πf (t-2td), therefore, the output signal of the output terminal (28) is (1+K Co52πftd
) ・sin 2 ft f (t-td).

FIG. 7 (only the level is expressed logarithmically) shows the frequency characteristics of this equalizer circuit, where the peak corresponding frequency is selected as fp, and rp is expressed as 'P=%td.

Note that a magnetic disk can also be used as the magnetic recording medium.

Effects of the Invention According to the present invention described above, in a magnetic recording device that records a broadband signal by modulating it with an FM modulator on a magnetic recording medium exhibiting a monomodal reverse wavelength characteristic, during reproduction, It is possible to obtain a magnetic recording device in which there is no risk that the high frequency range of the FM demodulated broadband signal will deteriorate too much.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main parts of an example of a circuit of a VTR to which the present invention is applied; FIGS. 2 to 5 are characteristic curve diagrams for explaining the VTR to which the present invention is applied; FIG. 7 is a block diagram showing another example of a specific configuration of a part of the device shown in FIG. 1;
The figure is a characteristic curve diagram thereof, and FIGS. 8 to 13 are characteristic curve diagrams for explaining the present invention. (1) is a recording system, (2) is a reproduction system, (5) is an FM modulator, (6) is a recording amplifier as an equalizer circuit, (7)
1 is a magnetic head, (8) is a magnetic tape as a magnetic recording medium, (11) is an equalizer circuit, and (12) is an FM decompressor. Same as Hidemori Matsukuma Figure 1 Figure 2 Figure 3 Figure 6 Figure 7 Figure 8 Figure 8- Figure 12 'yn j- Figure 10! = Figure 11! = Figure 13! −

Claims (1)

[Claims] In a magnetic recording device that modulates and records a wideband signal using an FM modulator on a magnetic recording medium with a monomodal reverse wavelength characteristic, the low frequency band below the vicinity of the highest frequency of the wideband signal is enhanced. A magnetic recording device characterized in that an equalizer circuit is provided at a subsequent stage of the FM modulator.