JPS62175967A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To remove the effect of the speed fluctuation in the recording medium of a wow and flutter, etc., to improve the performance by obtaining the signal corresponding to the speed fluctuation of the recording medium from the reference signal at reproducing time by recording the reference signal in a separate channel and by correcting the level variation of the reproducing signal by using it. CONSTITUTION:The reference signal C having been recorded in a separate channel is picked up by a head 12, becomes a signal (f) by being amplified with a reproducing amplifier 14 and further is inputted into an FM demodulater 13 via a PLL circuit 21. This signal (f) is made to accompany the level variation of the level of the output signal (g) of the FM demodulator 13 becoming high in case of the speed of the recording medium being faster and low in case of slower since the frequency of this signal (f) becomes high in case of the speed of the recording medium becoming after and low in case of slower. It is not controlled by correction circuit 8 so as to restrain the level variation by correcting the level of the signal (e) by using a signal (g). In this way the signal that the effect of the speed variation is removed from the signal (e), namely the original information signal (a) is reproduced with fidelity at the output side of the correction circuit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a magnetic recording/reproducing device, and particularly to one that eliminates the influence of speed fluctuations of a recording medium.

<Prior Art and its Problems> For example, when recording and reproducing video signals on a magnetic tape, it is common practice to perform frequency modulation during recording and frequency demodulation during reproduction. In the case of this type of system, if there are speed fluctuations such as wow or 7 rattuas in the running of the magnetic tape, the reproduced signal will be frequency modulated by this speed fluctuation, and the level of the reproduced video signal will fluctuate. A problem arises.

Measures have been taken to reduce wow and platter by improving the tape running system, but improvements to the running system tend to complicate the tape system and increase costs, and there are limits to its effectiveness. Therefore, it was difficult to take sufficient measures.

The present invention has been made based on this point, and is aimed at eliminating the influence of speed fluctuations by electrical signal processing.

Means for Solving the Problems> In order to achieve the above objects, the magnetic recording and reproducing system of the present invention
crll performs pre-emphasis processing on high-frequency components of information signals to be recorded and played back, such as video signals, during recording and de-en7assist processing during playback, and furthermore, separately from this information signal, A reference signal with a constant frequency is recorded on a separate channel, and the level of the reproduced information signal is controlled using the signal obtained by frequency demodulating the reproduced reference signal during reproduction to suppress its fluctuation. 6 Effects> Since the high frequency components of the information signal are pre-enhanced during recording and de-emphasized during playback, the effects of speed fluctuations with high frequency components such as 7 ripples are reduced. are sufficiently removed.

In addition, if there is a speed fluctuation with a relatively low frequency component such as wah, the frequency of the reproduced reference signal will change according to this speed fluctuation, so the signal obtained by frequency demodulating this will be affected by the speed fluctuation. The level changes accordingly. Therefore, by using this signal to perform control to suppress level fluctuations in the reproduced information signal, the influence of speed fluctuations can be removed.

<Example> Next, an illustrated embodiment will be described.

FIG. 1 is a block circuit diagram of the main part, and FIG. 2 is a characteristic diagram of a pre-emphasis circuit and a de-en-7 assist circuit.

The information signal a is input to the pre-emphasis circuit 1 shown in the rjS1 diagram, where the high-frequency components are emphasized.The information signal a is modulated by the FM modulator 2, amplified by the recording amplifier 3, and then recorded on a magnetic tape or the like by the head 7. Written on medium (not shown)!
I will be treated. A reference signal oscillator 5 oscillates a reference signal C having a stable frequency.The reference signal C is amplified by a recording amplifier 6 and then recorded by a head 12 onto another channel of the recording medium. 4 is an oscillator for magnetic recording bias signals.

During playback, the signal picked up by the head 7 is amplified by a playback amplifier 11 and demodulated by an FM modulator 10 to obtain a playback signal d. This signal d is basically input to an FM modulator 2. The signals are the same, but if there is a speed fluctuation in the recording medium, it will be affected by it; the faster the speed, the higher the level, and the slower the speed, the lower the level.

This signal d becomes a signal e whose high frequency components are compressed by the de-en7 assist circuit 9. The broken line in FIG. 2 shows the characteristics of the de-en7 assist circuit 9. This signal e has an improved S/N ratio due to pre-en-7 assist during recording and de-en-7 assist during playback for high-frequency components, and further increases It is basically the same as the information signal a, but the speed fluctuations with high frequency components are suppressed.
If there is a speed fluctuation with a low frequency component such as wah, it will be affected, and as the speed becomes faster, the level will become higher, and as the speed becomes slower, the level will become lower.

On the other hand, the reference signal recorded in another channel is picked up by the head 12, amplified by the reproducing amplifier 14 to become the signal f, and further passed through the PLL circuit 21 to the FM demodulator 1.
3 is input. This signal r is basically the same as the reference signal C, but note! 1 The faster the speed of the medium, the higher the frequency, and the slower the speed of the medium, the lower the frequency.
The output of No. 3 (the level of No. 3 (i) and g is accompanied by level fluctuations such that it becomes higher when the speed of the recording medium is faster and becomes lower when the speed of the recording medium is slow.

In this way, since the signal e and the signal g are simultaneously affected by the speed fluctuation, the correction circuit 8 corrects the level of the signal e using the signal g, and controls the signal to suppress the level fluctuation. . In this way, the output side of the correction circuit 8 receives the signal e.
The signal from which the influence of speed fluctuations has been removed, that is, the original information signal a, is faithfully reproduced.

In this embodiment, the reference signal reproducing circuit includes a PL.
This is by inserting the L circuit 21. Therefore, even if the signal f is lost due to dropout, the PLL
Since a signal having the frequency at the previous time point is obtained at the output side of the circuit 21, the stability of the reproducing operation does not deteriorate.

<Effects of the Invention> As is clear from the description of the above embodiments, the present invention has the following effects:
Pre-emphasis during recording and de-en-assist during playback are performed on high-frequency components of the information signal to be recorded and played back, and Standard No. 13 is recorded on a separate channel.
During playback, a signal corresponding to the speed fluctuation of the recording medium is obtained from this standard (No. The effects of this can be removed by electrical No. 13 processing, and the performance of magnetic recording and reproducing devices can be easily improved without complicating the running system mechanism or increasing costs. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of an instant embodiment of the present invention, and FIG. 2 is a block diagram of an instant embodiment of the present invention.
1, Y of pre-emphasis circuit and deen7 assist circuit
Sexual bacteria, 1... Preen 77 cis circuit 2... FM modulator 5... Reference signal oscillator 8... Correction circuit 9... Deen 7 assist circuit 10, 13... FM demodulator 21.・PLL circuit

Claims (1)

[Claims] 1. Frequency modulate the information signal and record it on a magnetic recording medium,
In a magnetic recording/reproducing device that demodulates the frequency to obtain the original information signal during playback, pre-emphasis processing is performed on high frequency components of the information signal during recording, de-emphasis processing during playback, and a certain level of frequency demodulation during recording. A reference signal having a frequency is recorded in a separate channel, and the reproduced reference signal is frequency-demodulated during reproduction, and the obtained signal is used to control the reproduced information signal so as to suppress level fluctuations. magnetic recording and reproducing device.