JPS61237208A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent a reproduced sound signal from deteriorating in SN ratio by providing a means which varies the amplitude of a recording current according to the frequency of the frequency-modulated wave of a sound signal and make the envelope of the frequency-modulated wave of the reproduced sound signal constant. CONSTITUTION:A resonance frequency is determined by the inductor of a rotary head 8 or 9 and a capacitor 17 and a signal is damped by a resistance 16 to give a recording amplifier 5 such frequency characteristics that the level increases with the frequency. Consequently, the level drop of each frequency component of a reproduced FM sound signal accompanying the characteristics of a head tape system is compensated to flatten the frequency spectrum of the reproduced FM sound signal. Therefore, the envelope of the FM wave becomes flat and the reproduced sound signal increases in SN ratio. Further, a circuit constant is only set and an increase in the cost is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic recording and reproducing device that frequency-modulates and records and reproduces audio signals.

[Background of the invention]

A so-called Hi-7 eye video tape recorder (hereinafter referred to as Hi-Fi VTR) that records and plays back audio by FM modulating it.
As shown in Figure 1, the frequency spectrum of the FM signal after FM modulation of the audio signal has a center carrier frequency f.
There are sideband waves on both sides of the sideband wave, and various frequency components exist between the lower limit frequency fr and the upper limit frequency fH of the sideband wave.

When this FM signal is recorded and reproduced, the reproduced FM signal spectrum becomes as shown in FIG. 2 due to the characteristics of the head-tape system, and the waveform of the reproduced FM signal becomes as shown in FIG. 5. As is clear from these characteristic diagrams, the amplitude is large in the low frequency part, and the amplitude is small in the high frequency part, causing an amplitude change.
N will deteriorate.

The document that describes the Hi-Fi video system is "Television Technology '84 issue, pages 27 to 29.
Published by Page TV Gijutsusha.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide an inexpensive magnetic recording and reproducing apparatus that can keep the envelope of a frequency modulated wave of a reproduced audio signal constant and prevent S/N deterioration.

[Summary of the invention]

To achieve this objective, the present invention provides F
The decrease in the level of the frequency component of the M audio signal was compensated for during recording.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIGS. 5 and 6 below.

This will be explained with reference to FIG.

FIG. 5 is a block diagram of the present invention, in which 1 is an input terminal;
2 is an input processing section, 5 is an FM modulation section, 4 is a bandpass filter, 5 is a recording amplification section, 6.7 is a switch, 8.9 is a rotary head, 1o is a reproduction amplification section, 11 is a bandpass filter, 12 1 is an FM demodulation section, 15 is an output processing section, and 14 is an output terminal.

In the figure, an audio signal from an input terminal 1 is subjected to processing such as pre-emphasis in an input processing section 2, and then supplied to an FM modulation section 5 where it is FM modulated. Then left channel (Lc le)”! 1.5MHz, right fat at 7
The channel (Rt-A) passes through a 1.7 MHz bandpass filter 4, is supplied to a rotary head 8.9 via a switch 6.7, and is recorded on a tape by the head. During playback, the playback signal from the rotating head 8°9 is amplified by the playback amplification section 10, passed through a bandpass filter, and then sent to the FM demodulation section t.
2, where it is FM demodulated, and an output processing section 15 performs processing such as de-emphasis to obtain an output signal 14.

Here, by providing a recording current equalization circuit as shown in FIG. 4 between the recording amplifier section 5 and the switch 6, the above-mentioned
7N can be improved, but this tends to be costly.

The present invention corrects this problem, and the recording amplification section 5
The circuit constants are set as follows to provide the same function as the recording current equivalent circuit shown in FIG. That is, in FIG. 6, 8.9 is a rotary head, 16 is a resistor, 17 is a DC cut capacitor, and 5 is a recording amplifier. Inductor and capacitor 1 of rotating heads 8 and 9
7 determines the resonance frequency, and resistor 16 damps it.
The recording amplifier 5 has frequency characteristics as shown in FIG. Thereby, it is possible to compensate for the level drop of each frequency component of the reproduced FM audio signal due to the characteristics of the head-tape system, and to flatten the frequency spectrum of the reproduced FM audio signal. Therefore, the envelope of the FM wave becomes flat, and the 87N of the reproduced audio signal is improved.

In addition, since it is only necessary to set circuit constants, it can be realized without increasing costs.

[Effects of the Invention] As explained above, according to the present invention, it is possible to flatten the envelope of a reproduced FM audio signal without increasing costs and without being affected by the characteristics of the head-tape system. /
N good audio signals can be reproduced.

[Brief explanation of drawings]

Figure 1 shows the frequency spectrum of the FM audio signal during recording.
Figure 2 shows the frequency spectrum of the reproduced FM audio signal, Figure 5 shows the waveform of the reproduced FM audio signal, Figure 4 shows a specific example of a recording current equivalent circuit, and Figure 5 shows the magnetic field of the present invention. FIG. 6 is a block diagram showing an example of a recording/reproducing apparatus, FIG. 6 is a circuit diagram of a recording amplifier section of the present invention, and FIG. 7 is a frequency characteristic diagram of the recording amplifier of the present invention. G... Input signal, 2... Input processing unit, 5... FM modulation unit, 4... Band pass filter, 5... Recording amplification unit, 6.7... Switch, 8, 9...・Rotating head,
10... Reproduction increase s part, ■... Band pass filter,
12... FM demodulation section, 15... Reproduction processing section, 14.
...Output signal, 16...m resistor, 17...capacitor. To substitute / J% Jll fat man -゛-1st (21 夷2I!l 3121 稟4 5th time 73Mh A7stfx

Claims (1)

[Claims] In a magnetic recording and reproducing device that frequency modulates an audio signal and records it in the deep part of the tape using a rotating head, the amplitude of the recording current is changed according to the frequency of the frequency modulated wave of the audio signal, and the reproduced audio signal is A magnetic recording/reproducing device characterized by being provided with means for making the envelope of a frequency modulated wave constant.