JPH03211991A - Magnetic recording system - Google Patents

Abstract

PURPOSE:To correct a time base variance component with a high precision without requiring a complicated color synchronizing circuit at the time of reproducing by recording a continuous signal, whose frequency is N times as high as a low band converted frequency, as the pilot signal at the time of recording. CONSTITUTION:At the time of recording, frequencies of a signal 2 which has the frequency and the phase synchronized with the burst signal of a carrier chrominance signal 1 and a signal 3 having the low band converted frequency are converted by a frequency converter 6 to generate a carrier signal 7 for con version of the carrier chrominance signal l in the low band. The frequency of the carrier chrominance signal 1 is converted by a frequency converter 4 to obtain a low band converted color signal 5; and meanwhile, the signal 3 having the low band converted frequency is inputted to a multiplier 8 to generate a pilot signal 9 whose frequency is N (an integer >2) times as high as the low band converted frequency. The low band converted color signal 5 and the pilot signal 9 are added by an adder 10, and the resultant signal is recorded as a recording signal 11 on a recording medium 12. At the time of reproducing, a carrier signal for frequency conversion generated by the pilot signal 9. Thus, phase synchronism and time base variance components are corrected without requiring a PLL at the time of reproducing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording system for video signals, and particularly to a recording system for low-frequency conversion of color signals.

[Conventional technology]

Conventionally, the recording method that performs low frequency conversion of color signals is as shown in 14.2 Color Signal System on pages 164 to 171 of "Introduction to Home VTR" by Katsuya Yokoyama, Akira Hirota, and Yoshimi Watanabe (published by Corona Publishing). As shown, during playback, the phase comparator, VCO (
PLL (phase control) called APC (automatic phase control)
A locked loop) is constructed, thereby obtaining a carrier color signal having a regular color subcarrier frequency. Also, the 169th
As shown on page 14.2.9, this PLL corrects the time axis fluctuation component that occurs during recording and reproduction.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, it is necessary to perform phase synchronization using a PLL when reconverting to the original carrier color signal during reproduction. In addition, the time axis fluctuation component caused by fluctuations in the running of the recording medium tape or head during recording and playback is
Corrected by LL. That is, the performance of the PLL occupies a large proportion of the performance during playback. However, the PLL for color signal processing has a problem in that it is difficult to design control gains, filters, etc. because its phase detection is partial detection using a burst signal of the color signal.

An object of the present invention is to provide a magnetic recording method that performs phase synchronization and correction of time axis fluctuation components during reproduction without requiring a PLL.

[Means to solve the problem]

In order to achieve the above object, the present invention generates a signal N times the low frequency conversion frequency during recording, and records the signal as a pilot signal together with the low frequency conversion color signal on the same tape. Further, during reproduction, a carrier signal for frequency conversion is created using this pilot signal, thereby obtaining a carrier color signal having a regular color subcarrier frequency.

[Effect]

FIG. 1 shows a block diagram of a color signal processing section during recording and reproduction according to the present invention.

During recording, a frequency converter 6 converts a signal 2 whose frequency and phase are synchronized with the burst signal of the carrier color signal 1 and a signal 3 having a low frequency conversion frequency, and converts the carrier color signal 1 to a low frequency. Create carrier signal 7. The carrier color signal 1 is frequency-converted by a frequency converter 4 and becomes a low frequency converted color signal 5.
get. On the other hand, the signal 3 having the low conversion frequency is input to a multiplier 8, and a pilot signal 9 having a frequency N times the low conversion frequency is generated. Here, N takes an integer value of 2 or more. The low frequency conversion color signal 5 and the pilot signal 9 are added by an adder 10 and recorded on a recording medium 12 as a recording signal 11.

During reproduction, the reproduction signal 13 reproduced from the recording medium 12 is
A pilot signal 22 is taken out by a BPF (band pass filter) 21 and divided by N by a frequency divider 14 to obtain a signal 15 having a low frequency conversion frequency. This signal and a signal 16 having a regular color subcarrier frequency are frequency-converted by a frequency converter 17 to create a carrier signal 18 for frequency-converting the low-pass converted color signal 24. In addition, the playback signal 13
is input to an LPF (low pass filter) 23 to obtain a low frequency converted color signal 24, and this signal is further input to a frequency converter 1.
9 to obtain a regular carrier color signal 20.

This eliminates the need for frequency and phase synchronization using a PLL during playback as in the past, and since the pilot signal 9 is recorded on the same recording medium as the low-pass conversion color signal 5, the pilot signal 22 during playback and the low frequency converted color signal 24 contain the same time axis variation component, and the time axis variation component is canceled out in the carrier color signal 20 which is the final output. In this way, a system with the same function as color signal processing using a conventional PLL can be realized with a relatively simple configuration, and in particular, correction of time axis fluctuation components can be performed with high precision.

〔Example〕

FIG. 2 shows an example of signal processing during recording when the present invention is implemented.

The video signal 25 is passed through the LPF 26. The BPF 32 separates the signals into a luminance signal 27 and a carrier color signal 1, respectively. The luminance signal 27 is frequency modulated by the recording luminance signal processing section 28,
#L signal 29 is obtained. on the other hand.

The carrier color signal 1 is frequency-converted by a frequency converter 4 to obtain a low frequency converted color signal 5. Further, a PLL is configured by a phase detector 33 and a VCO 34 that oscillates at the color subcarrier frequency, and uses the burst signal of the carrier color signal 1 to obtain a continuous signal 2 synchronized in frequency and phase with the burst signal. This continuous signal 2 and a signal 3 having a low frequency conversion frequency obtained by the VCO 36 and the frequency divider 37 are input to the frequency converter 6, and the B
A carrier signal 7 for frequency converting the carrier color signal 1 is obtained via the PF 35. Signal 3 with low conversion frequency is
Further, the signal is multiplied by N by a multiplier 8 to obtain a pilot signal 9. Finally, the low frequency conversion color signal 5 and the pilot signal 9 are added by an adder 10, and this signal and the luminance recording signal 29 are added together.
are added by an adder 3° to obtain a video recording signal 31.

FIG. 3 shows the frequency components of the video recording signal 31.

As shown in the figure, the pilot signal 39 is inserted between the low frequency converted color signal 38 and the frequency modulated luminance signal 40.

FIG. 4 shows an example of signal processing during reproduction. The reproduced signal 13 reproduced from the magnetic head is converted into a reproduced luminance signal 42, a low frequency conversion color signal 24 . The signal is separated into pilot signals 22. The reproduced luminance signal 42 is demodulated by a reproduced luminance signal processing section 43 to obtain a luminance signal 44 in the video signal. The pilot signal 22 is frequency-divided by N by a 1-frequency divider 14 to obtain a signal 15 having a low frequency conversion frequency. This signal and the output signal 16 of the reference oscillator 47 that oscillates at the regular color subcarrier frequency are input to the frequency converter 17, and the BPF
48, a carrier signal 18 for frequency converting the low frequency conversion color signal 24 is obtained. The frequency of the low frequency converted color signal 24 is converted into a regular carrier color signal 2o by a frequency converter 19, and this signal and the luminance signal 44 are added by an adder 45 to obtain a video signal 46. In this way, color signal processing during reproduction does not require a complicated synchronization circuit, resulting in a relatively simple system.

〔Effect of the invention〕

The present invention does not require a complicated color synchronization circuit using PLL in color signal processing during playback, and it is possible to accurately correct time axis fluctuation components, thereby reducing costs and improving performance. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of a color signal processing unit during recording and reproduction according to the present invention. FIG. 2 is a block diagram showing an example of signal processing during recording. FIG. 3 is a waveform diagram showing frequency components of a recording signal. FIG. 4 is a block diagram showing an example of signal processing during reproduction. DESCRIPTION OF SYMBOLS 1... Carrier color signal, 4... Frequency converter, 6... Frequency converter, 7... Carrier signal, 8... Multiplier, 9...
...Pilot signal, 11...Record signal, 13...
Reproduction signal, 14... Frequency divider, 17... Frequency converter, 18... Carrier signal, 19... Frequency converter,
20...Carrier color signal, 21...BPF, 22...Pilot signal, 23...LPF, 24...Low frequency conversion color signal. Takunidai

Claims (1)

[Claims] 1. In a magnetic recording method for video signals that performs low frequency conversion of color signals, a continuous signal having a frequency N times the low frequency conversion frequency (N is an integer value of 2 or more) is recorded as a pilot signal during recording, A magnetic recording method characterized by using this pilot signal during reproduction to reconvert the low frequency converted color signal into the original carrier color signal.