JPS58105412A - Recording and reproducing device of pcm system - Google Patents

Abstract

PURPOSE:To enable the dubbing between the devices of different sampling frequencies, by controlling the frequency of the master clock in response to the external synchronizing signal. CONSTITUTION:A switch 30 is switched to the side (a), and the signal (fSIN) delivered from a crystal oscillator 25 is applied as the reference frequency signal of a phase comparator 26. In this case, the constant of an LPF27 and the dividing ratio of a frequency dividing circuit 29 are decided previously in order to obtain a master clock (MCIN) of a prescribed frequency from a voltage control oscillator 28. The master clock is divided by a frequency dividing circuit 31 to obtain the frequencies (fS, fC1, fC2). While the switch 30 is set at the side (b) and at the same time an external digital data supplied through a terminal T2 is selected in case the external synchronizing signal (fSBX) is used for operation. Thus the master clock (MCBX) of the oscillator 28 is set as MCEX=f'SEX/fSIN.M CIN which is controlled by the external synchronizing signal. Then the clock (MCBX) is divided by the circuit 31 to obtain a new sampling frequency corresponding to the external digital data.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a pulse code interval m (hereinafter referred to as P) configured such that the frequency of a master clock is controlled by an external synchronization signal.
The purpose of the present invention is to provide a recording/reproducing device using the CM (commercial information) system.

Conventionally, when talking about externally synchronized operation in this type of device, the same standard,
Connections were mainly made between members of the same format. For example, if the sampling frequency is 44 K II m
+ Master clock (R wave number) is 44KHgXM
(integer) times, and by receiving and receiving the determined frequency, operation was performed according to the external period. The present invention provides the following methods to perform
By having a configuration in which the frequency of the master clock can be controlled, it is possible, for example, to perform dubbing between devices whose master clock frequencies are different from each other.

A fixed magnetic head type PCI recording/reproducing apparatus will be explained below as an example. FIG. 1 shows its block diagram.

This embodiment is an example in which recording is performed on N tracks using the frame distribution method.

The input analog signal is passed through a low pass filter (LPF
) 117, +21 remove unnecessary bands, sample and hold circuit +31141, multiplexer (
5) The left and right signals are alternately converted into digital signals by the ^/D conversion circuit (6). An error checking and correcting code is added to data of a predetermined block length for each frame by an error checking and correcting code adding circuit (7), and the data is distributed to each track by a frame distribution circuit (8). Furthermore, after being converted into a low-speed signal by a time axis conversion circuit (9:), it is subjected to, for example, MFM modification in a modulation circuit 1G, and a frame synchronization signal is added.
The recording circuit fills the magnetic head [21 to record the data on the tape]. During playback, the signal from each magnetic head d- is sent to the playback amplification circuit 1! After being amplified and equalized by il,
Demodulation/synchronization separation circuit (demodulates to digital signal in II,
Synchronized and separated. The demodulated signal is converted into a high-speed signal by the time axis conversion circuit aη, combined by the multiplexer 18, and further subjected to code error correction/correction in the code error detection/correction circuit di. Then, it is output as the original analog signal by the D/A converter (2), demultiplexer, Q, and LPFjpJ.

Now, in the past, a master clock with a constant frequency was divided by a predetermined frequency division ratio to obtain the sampling frequency (f, etc.). Digital dubbing etc. were only possible under controlled conditions.

By the way, in a fixed magnetic head type PCI recording/reproducing apparatus, when the frequency of the master clock is changed, there is no need to make any changes to the circuit configuration or recording format. This will be explained with reference to FIG.

A/with sampling frequency (fs) and quantization bit number of 181
The D-converted data (Fig. 2a) has an error calibration correction code 101 added to every m words, and a clock frequency (f
cl) signal (Fig. 2b). This signal is time-base converted, becomes a signal with a clock frequency (to), and is distributed and recorded on each track (FIG. 2C).

At this time, the frame synchronization signal [How many bits does it have? ] is recorded at the beginning of each frame. Clock (fo) is 01XB107 from Figure 2. "11 g+x's+c? 2 T21 Also, T2 = (N-1)・T1...
3] (1/f*JXm-Tl ”... (41, so +11 T21 '31 f(32x
-# fc1 -1 :1) (from the play, mX H+C f 01 ; -m f). Then, C, the master clock foo is selected so as to be a common multiple of these frequencies fs, fat, and fcz. Then, if each master clock signal output from a crystal oscillator or the like is divided by a predetermined division ratio, fs,
You can get fc+ and fax.

As mentioned above, fco, fs, fel, fat
As long as the relationship ^ is added, there is no need to change the circuit configuration or recording format even if the value itself of rao etc. is changed.

Therefore, the present invention has a configuration in which the frequency of the C1-2 star clock can be changed based on the external periodic signal applied from the terminal (T). , Crystal oscillation in 6 countries, Phase comparison II @, L
P17), a voltage controlled oscillator (to), and a branch circuit.

Normally, the switch ■ is switched to the a side, and the phase comparison 'J
As a 1m reference frequency signal, a crystal JIi device (2) is used.
A signal (fsl) is applied.

In this case, the constant of the LPF 2 and the division ratio of the frequency divider circuit are determined so that a master clock (Mat) of a predetermined frequency can be obtained from the voltage controlled oscillator.

Then, a frequency dividing circuit (
In step 2), by dividing with a predetermined frequency division ratio, (fs, fat, fo) of a predetermined frequency is obtained.

On the other hand, when operating the device using external periodic signal (f-m
External digital data that is manually input is selected.

At this time, the output of the voltage controlled oscillator (to), that is, the master clock (MOL) becomes the master clock that is controlled by the external periodic signal by °C. A new sampling frequency, etc. according to external digital data can be obtained by dividing the data in the dividing circuit.

During playback, the regenerated synchronization signal synchronously separated by the demodulation/synchronization separation circuit U@ is used as the reference frequency signal, and the phase-locked loop (to) [phase comparator (to), LPF-1 voltage controlled oscillator ( A predetermined signal C1 is obtained by applying the signal to the C1 circuit (to) and the branch circuit (to) to generate a master clock on the reproduction side, which is then divided by °C to the frequency dividing circuit (to). The capstan motor (to) is controlled by a servo circuit using the output of the crystal oscillation S as a reference frequency signal.

According to the present invention described above, the frequency of the C and master clocks can be varied based on the external synchronization signal.
For example, it is possible to perform dubbing between devices that have different sampling frequencies.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a PCM recording and reproducing apparatus according to the present invention, and FIG. 2 is a diagram showing the relationship between the frame distribution recording format and each clock. ■ is the master clock generation circuit, (Tz, T is the terminal (
input section).

Claims (1)

[Claims] +1) Analog signal is converted into pulse code fil (PCMJ
This is a PCM type recording and reproducing device for recording and reproducing data on a recording medium such as a magnetic tape, which includes an input section for external digital data, an input section for an external synchronization signal synchronized with the external digital data, and ( A PCM recording and reproducing device characterized in that it has a master clock generation circuit whose frequency is controlled based on an external synchronization signal input manually from the input section of the PCM system. (2) The master clock generation circuit is a phase-locked loop. A PCM recording and reproducing apparatus according to claim 1, which is constructed of: