JPH01300409A - Digital magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve a transmission S/N by attaching the burst wave of a carrier signal at every specific time, and performing the orthogonal amplitude modulation of a multivalue digital code by using a clock signal to specify the relation of a frequency and the carrier signal. CONSTITUTION:The relation between the frequency fc of the clock signal and the frequency fH of the carrier signal is set as n.fc=m.fH (n<m, n, m: positive integer), and the burst wave of the carrier signal is attached by a burst wave attaching unit 3 at every T=l.m/fc=l.n/fH (l: positive integer). And the orthogonal amplitude modulation of the multivalue digital code is performed by using the clock signal and the carrier signal, and bias recording and reproduction are performed on a magnetic recording medium 8. Thereby, since it is possible to reproduce the clock signal and the carrier signal simultaneously at a reproduction side by using the burst wave, the frequency of the carrier signal can be set in an area lower than that of the frequency of the clock signal, and thereby, it is possible to use an intermediate area with a high transmission C/N on the magnetic recording medium 8, and to improve the transmission S/N.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a digital videotape recorder (DVT).
This invention relates to digital magnetic recording and reproducing devices such as R).

2. Description of the Related Art Conventional digital magnetic recording and reproducing apparatuses are based on saturation recording of binary signals, and baseband recording modulation methods such as the NRZI method and the 8-1o conversion method are often used (for example, [digital VTR "High-density magnetic recording technology used in the field" by Shozo Nakayo, Journal of the Television Society, Vol. 35, No. 7 (1981), pp. 542-548).

In the field of communications, multi-value digital modulation methods such as multi-value quadrature amplitude modulation (multi-value QAM) are still being introduced in order to make effective use of transmission bands. Since the reproduction process has non-linearity, only the PSK method in which the amplitude is constant is used in some cases.

Problems to be Solved by the Invention However, in the configuration using the above-mentioned baseband modulation method, the usage efficiency of the recording frequency band (the bit rate that can be transmitted per unit band) is 1.3 bps/Hz.
This leads to an increase in tape consumption and makes long-term recording difficult.

Unfortunately, if the orthogonal modulation signal obtained by QAMing the multilevel digital code is recorded with a bias, it is not affected by the nonlinear shape of the magnetic recording medium and it is possible to increase the utilization efficiency of the recording frequency band. Since it is based on a value digital code, there is a problem in that the required S/N for transmission increases.

In view of the above-mentioned problems, the present invention provides a digital magnetic recording/reproducing apparatus in which the transmission S/N is improved by using a medium frequency with a good transmission C/N of a magnetic recording medium.

In order to solve the problems described in "Means for Solving the Problems", the relationship between the frequency of the clock signal (fC) and the frequency of the carrier wave signal (fH) is
fC=m−fH(n (m, n, m are positive integers), T
A burst wave of a carrier signal is added every =l-m/fC=t-rh/fH (l is a positive integer), and the multilevel digital code is orthogonally amplitude modulated using the clock signal and the carrier signal. A digital magnetic recording and reproducing device 5, - for recording and reproducing information on a magnetic recording medium, detecting orthogonal amplitude modulation signals reproduced from the magnetic recording medium to generate one axis of a multilevel digital code. A synchronous detector that generates a signal and a Q-axis signal, an error signal generator that generates an error signal indicating the amount of time-axis fluctuation based on the 1-axis signal and the Q-axis signal, and , a signal selector that generates a control signal for selecting an error signal, and a timing controller that extracts only the error signal whose time axis fluctuation is correctly output according to the control signal and the reproduction clock signal;
Based on the output of the timing controller, the frequency f=n・f
A voltage controlled oscillator that generates a signal according to the time axis fluctuation of C=m-fH, a frequency divider that divides the output signal from the voltage controlled oscillator by n and 9m, and a frequency that is extracted from the quadrature amplitude modulation signal. a phase selection unit that simultaneously reproduces the reproduction clock signal and the carrier wave signal by determining the phases of the reproduction clock signal and the carrier wave signal generated by dividing the frequency by n and dividing the frequency by 1m in a frequency divider according to the phase of the burst wave generated by the burst wave; It has a configuration with

Operation The present invention has the above-described configuration, so that the clock signal stations 6/, -
7. A carrier wave signal set at a lower frequency than the wave number and the clock signal can be simultaneously reproduced,
The carrier wave frequency used for QAM can be set as low as possible compared to the clock signal frequency, and the transmission S/N can be improved by using a mid-range frequency with a good transmission C/N of the magnetic recording medium. It is something.

EXAMPLE Hereinafter, a digital magnetic recording medium device fiff, which is an example of the present invention, will be described with reference to the drawings.

FIG. 1 is a block diagram showing the main structure of a digital magnetic recording and reproducing apparatus in an embodiment of the present invention. On the recording side, using the clock signal output from the clock carrier timing signal generator 4, the multi-level digital code generator 1 outputs I-axis and Q-axis signals of the multi-level digital code.

Next, in the QAM unit 2, the clock signal station mantissa (:fC) output from the clock carrier timing signal generator 4
The frequency relationship with n·fC = m−fH7, . 7 (n (m, n, m is a positive integer) using a carrier wave signal with a frequency FH, quadrature amplitude modulates the 1-axis signal and Q-axis signal of the multi-level digital code, and outputs the burst adder 3. Output to.

In the burst adder 3, T=l-m/fC-1-n is output from the clock carrier timing signal generator 4.
A burst wave of the carrier signal is added according to the timing of /fH (n is a positive integer). That is, T=l-m/f
Since a burst wave is added at each C=ln/fH timing, the burst wave indicates the phase of the carrier signal and the phase of the clock signal at the same time.

The adder 5 adds the bias signal generated by the bias signal generator 6 and the orthogonal amplitude modulation signal, and performs bias recording on the magnetic recording medium 8 via the magnetic head 7.

Next, the playback side will be explained. On the reproduction side (d), the orthogonal amplitude modulation signal is reproduced from the magnetic recording medium 8 via the magnetic head 7.The reproduced orthogonal amplitude modulation signal is detected by the synchronous detector 11 using the carrier wave signal and multiplexed. The ■-axis signal and the Q-axis signal of the value digital code are output.At the same time, the signal selector 13 uses the detected 1-axis signal and the Q-axis signal of the multi-value digital code to output the x-axis signal and the Q-axis signal. When a signal in the equicircled area is reproduced (for example, in the case of 16-value transmission,
When the signal is reproduced in the shaded area shown in Figure 2), " 1
” control signal is generated, and other than the above, a control signal of °°0°' is generated.

On the other hand, for example, in the case of 16-value transmission, the error signal generator 12 is connected to an adder 21 . Subtractor 22, identification 1i23, 24°25.26 from the limiter circuit. EX-
It is composed of OR circuits 27, 28, and 29, and generates an error signal indicating the amount of time-axis fluctuation from the single-axis signal and Q-axis signal of the multilevel digital code detected by the synchronous detector 11. However, except for multilevel digital codes that are equidistant from the {circle around (2)} axis and the Q axis (1), the error signal output from the error signal generator 12 is a signal that does not correctly indicate the amount of time axis variation.

Returning to FIG. 1, the timing controller 14 outputs the control signal 11111 and the output of the signal selector 13.
According to '○' and the reproduced clock signal, the error signal generator 12 outputs only the error signal that correctly outputs the time axis variation and outputs it to the LPF '16.
If the error signal is not output correctly from the error signal generator 12, the previous correct error signal is held and the LPF 1
Output to 5.

Next, the LPF 16 removes unnecessary high frequency components and outputs a signal indicating time axis fluctuation to the voltage controlled oscillator 16. In the voltage controlled oscillator 16, the frequency f=n・fC=
Generates a signal according to the time axis fluctuation of m-fH and divides it into n frequency divider 1.
72m frequency divider 18.

In the n frequency divider 177m frequency divider 18, the voltage controlled oscillator 16
The signal outputted from is divided by n and frequency is divided by 2m, and a clock signal and a carrier wave signal according to the time axis fluctuation are output. Finally, phase selector 19, phase selection section 19-1. burst game) 19-2, burst gate 19-2
Now, a burst wave representing a carrier signal is extracted from the orthogonal amplitude modulation signal reproduced from the magnetic head 7 and output to the phase selection section 19-1. In the phase selection section 19-1, bar 0
A-7 Determine the phases of the clock signal and carrier wave signal according to the correct phase of the strike wave, and output the reproduced clock signal and carrier wave signal simultaneously.

As described above, according to the present invention, the clock signal frequency f can be adjusted on the recording side of a digital magnetic recording/reproducing device. and the carrier signal frequency beat are ==H/rn ・fc (
However, n≦m, n, m are positive integers), and furthermore, T
A burst wave of the carrier signal is added every =l-m/fo=l-n/fH (where β is a positive integer). However, since the clock signal and carrier wave signal can be simultaneously reproduced using the burst wave on the reproduction side, the frequency of the carrier wave signal can be set to a lower frequency range than the clock signal frequency. Therefore, the middle range of the magnetic recording medium with a good transmission C/N can be used, and the transmission S/N can be improved.

On the reproducing side, the clock signal and carrier wave signal are reproduced using the detected I-axis signal and Q-axis signal of the multilevel digital code, so the time axis fluctuation 11 /\-7 can be accurately It can be followed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the main parts of a digital magnetic recording/reproducing device according to an embodiment of the present invention, Fig. 2 is a signal arrangement diagram showing signal selection in the case of 16-value transmission, and Fig. 3 is the case of 16-value transmission. FIG. 2 is a block diagram of main parts of an error signal generator of FIG. 1... Multilevel digital code generator, 2-QAM device,
3... Burst adder, 4... Clock carrier wave timing signal generator, 6 Adder, 6 Bias signal generator, 7 ・Magnetic head, 8 Magnetic recording medium, 11- ・
Synchronous detector, 12 Error signal generator, 13 Signal selector, 14 Timing controller, 15 LPF
, 16 voltage controlled oscillator, 17...n frequency divider, 1
8...m frequency divider, 19...phase selector, 19-1...
・Phase selection section, 19-2 Burst gate, 21
Adder, 22...Subtractor, 23, 24, 25.26...
...Discriminator, 2nd round, 28.29...EX-OR circuit.

Claims (2)

[Claims] (1) Express the relationship between the frequency of the clock signal (f_C) and the frequency of the carrier signal (f_H) as n・f_C=m・f_H(
n≦m, n, m are positive integers), T=l・m/f_C
A burst wave of a carrier wave signal is added every =l・n/f_H (l is a positive integer), and the multilevel digital code is orthogonally amplitude modulated using the clock signal and the carrier wave signal to be recorded on the magnetic recording medium. A digital magnetic recording and reproducing device for bias recording and reproducing, the synchronous detector detecting a quadrature amplitude modulation signal reproduced from the magnetic recording medium to generate an I-axis signal and a Q-axis signal of a multilevel digital code. an error signal generator that generates an error signal indicating the amount of time-axis fluctuation based on the I-axis signal and the Q-axis signal; and a control for selecting the error signal based on the I-axis signal and the Q-axis signal. a signal selector that generates a signal, a timing controller that extracts only the error signal that correctly outputs the time axis fluctuation according to the control signal and the reproduction clock signal, and based on the output of the timing controller, the frequency f= n・f_C=m・f_H
a voltage controlled oscillator that generates a signal according to the time axis fluctuation of the voltage controlled oscillator, a frequency divider that divides the output signal from the voltage controlled oscillator by n and m, respectively, and a burst extracted from the quadrature amplitude modulation signal. Phase selection for simultaneously reproducing the reproduction clock signal and the carrier wave signal by determining the phases of the reproduction clock signal and the carrier wave signal generated by frequency division by n and m in the frequency divider according to the phase of the wave. A digital magnetic recording and reproducing device comprising: (2) The signal selector uses two orthogonal I axes of orthogonal amplitude modulation.
2. The digital magnetic recording and reproducing apparatus according to claim 1, wherein signals having equal distances from the Q-axis and the Q-axis are selected.