JPS58100207A - Recording and reproducing device for digital signal - Google Patents

Abstract

PURPOSE:To facilitate program search for a desired point by recording a digital signal in the form of a signal which has energy corresponding to its and reproducing an analog signal corresponding to the energy of a signal to be picked up during fast forwarding and rewinding. CONSTITUTION:A digital signal A to be recorded is converted by a converting circuit 1 into a recording format signal B which has energy EXT corresponding to its level, and the signal is recorded on a recording medium 3 by a recording circuit 2. For normal-speed reproduction, an energy reproduction output C is obtained from the recording medium 3 by a reproducing circuit 4 and supplied to a waveform shaping circuit 5 to obtain a signal D of the same format with the signal B. This is converted into a reproduced digital signal E through a reverse converting circuit 6. For fast-forwarding or rewinding reproduction, the signal C is passed through a low-pass filter 7 to obtain a reproduced analog signal F corresponding to the energy EXT. Thus, program search for a desired point is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital signal recording and reproducing device.

In general, digital signal recording and reproducing devices are required to be capable of recording as large a capacity as possible215. However, short wavelength, high-density recording and playback are normally used, and for this reason, it is difficult to reproduce the recorded digital signal when the tape is fed at a speed higher than the specified speed, that is, in fast-forward, two-rewind mode. is generally impossible.

We will explain a PCM recorder that uses magnetic tape as an example of a digital signal playback device.In the conventional system, when you want to play back a certain part of a recorded tape, the tape position cannot be clearly determined using a tape counter or the like. If possible, feed the tape at an appropriate position in the half-winding state of fast forwarding or rewinding, try playing it at the normal speed, listen to the playback sound, and check whether the desired tape position has been reached. If it is not, repeat the operation of winding the tape half way again, feeding the tape to an appropriate position, and trying to play it again at the normal speed, which takes time and effort to locate the beginning of the tape at the desired position and play it back. Operation was necessary.

The present invention overcomes these drawbacks of the conventional power, and
Even during half-winding, fast forwarding, rewinding, etc., it is possible to cue the desired tape position while listening to the analog output signal as an audio output or observing the waveform with an oscilloscope. The figure is a diagram for explaining an example of a signal format having energy of a magnitude corresponding to the magnitude represented by a recorded digital signal used in the present invention.
; The digital value shown is 3 bits. The binary digital values for numbers 0 to 7 are respectively “
It corresponds to "oo○" to "111". The recording format, which is a pulse train corresponding to these digital values, corresponds to the one shown to the right of each digital value.
In this example, the number of pulses of height E9 and width T is made to match the original value. As a result, the energy of each recording format ranges from ○ (EXT) to 7 (
EXT), and it can be seen that the magnitude of each energy is proportional to the original value.

As shown in FIG. 2, the recorded digital signal A is converted by the format conversion circuit 1 into a recording format signal B having the recording format shown in FIG. 1, and is recorded on the recording medium 3 by the recording circuit 2. During reproduction at the normal speed, an energy reproduction output signal C is obtained from the recording medium 3 by the reproduction circuit 4.

Then, the waveform shaping circuit 5 shapes the energy regeneration output signal C to obtain a pulse regeneration output signal.

Since this pulse reproduction output signal is in the recording format shown in FIG. 1, it is converted by the format inverse conversion circuit 5 into a reproduction digital signal E in binary format. This reproduced digital signal E is the same as the recorded digital signal A.

Next, a case of half-winding playback with two fast forwards and two backwards will be explained. Figure 3 shows a certain analog music signal converted into a digital signal, which is arranged as a numerical value string (a) of only 4 samples, and is made to correspond to a digital value in binary format (b), that is, a recorded digital signal A. This is further expressed as a recording format signal (c). It is clear that during normal speed reproduction, if the energy reproduction output signal () which is the output of the reproduction circuit 4 is waveform-shaped, it becomes the recording format signal (c).

If the pulse reproduction output signal (E) that should be output during double-speed fast winding was originally output correctly, it would be the recording format signal (C) shortened in half in terms of time, but in this case, the pulse reproduction output signal (E) that should be output from the recording medium 3 The output of the signal becomes too dense, and in reality, it becomes difficult to pick it up accurately even at the stage of the reproducing circuit 4.

When the energy of each sample of the pulse reproduction output signal (E) that should normally be output during double-speed fast winding is integrated and displayed for each sample, the waveform shown in (E) is obtained.

In other words, since the regeneration circuit 4 does not have sufficient resolution at half-winding, it is not possible to obtain an energy regeneration output signal C from the regeneration circuit 4 in which each pulse can be distinguished as shown in (2). much higher than the speed, e.g. 10
If the reproduction is performed at about twice the speed, an energy reproduction output signal C, which is integrated with the time constant of the reproduction circuit 4, which has a waveform similar to For example, if necessary as an acoustic signal, 20
The reproduced analog signal F can be obtained by extracting only the frequencies below KHz. As shown in (g), this reproduced analog signal F has a waveform that gently traces the level corresponding to the numerical value (a), and becomes an analog signal corresponding to the digital value (b).

As described above, the digital signal recording and reproducing apparatus of the present invention records the recorded digital signal on a recording medium using a signal format having a magnitude of energy corresponding to the magnitude represented by the recorded digital signal. When reproducing at a normal speed, the recorded digital signal is reproduced from the recording medium, and during fast forwarding and half-winding, a reproduced analog signal is reproduced according to the energy level of the signal picked up from the recording medium. By reproducing it, an analog signal output corresponding to the magnitude represented by the recorded digital signal is obtained. Therefore, compared to the conventional system, it is possible to perform fast forward mode, rewind mode, etc. Even at speeds higher than the specified playback speed, an analog signal of a size corresponding to the digital signal recorded on the recording medium can be obtained, so it has the excellent advantage of making cueing to a desired point extremely easy. .

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining an example of a signal format having energy of a magnitude corresponding to the magnitude of a recorded digital signal used in the present invention, and FIG. 2 is a diagram showing a digital signal recording/reproducing apparatus of the present invention. FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. 3 is a waveform diagram of each part for explaining the operation. 1...Format conversion circuit, 2...
Recording circuit, 3... Recording medium, 4... Reproduction circuit, 5... Waveform shaping circuit, 6... Format inverse conversion circuit, 7... ...Low pass filter. Name of agent: Patent attorney Toshio Nakao and 1 other person Vehicle 1
Figure 2

Claims (1)

[Claims] When the recorded digital signal is recorded on a recording medium using a signal former having a magnitude of energy corresponding to the magnitude represented by the recorded digital signal, 7) and the recorded digital signal is reproduced at a normal playback speed, the recorded digital signal is By reproducing the recorded digital signal from the medium and reproducing an analog signal corresponding to the energy level of the signal picked up from the recording medium during half-winding of fast forwarding and rewinding, the representation of the recorded digital signal is reproduced. A digital signal recording and reproducing device characterized in that it obtains an analog signal output according to its size.