JPS63100670A - Pcm signal reproducing device - Google Patents

Abstract

PURPOSE:To make the detection of an inter-music space easy and sure by detecting a fixed PCM according to the state of a digital signal. CONSTITUTION:An inter-music space detection circuit 34 is connected at a stage before a D-A converter 35. If the digital signal is inputted to the circuit 34, perfect zero level digital signals are detected which are stored in inter-music spaces B1-B6. When the signals are obtained continuously over a prescribed period, that is regarded as an inter-music space. Hence a musical program and the inter-music space are clearly discriminated and detected. The output of the inter-music space detection circuit 34 is given to an inter-music space signaling device or a control circuit, and it is used for search or automatic retrieval. Thus the inter-music space can be detected easily and surely in such a way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a PCM signal reproducing device that can easily and reliably perform cueing or automatic search of information blocks.

Conventional PCM recording signal cue or automatic search is performed by recording an address signal between information blocks and detecting this address signal during playback, or by inserting a silent period of a predetermined time or more between information blocks (between songs). ). The former method of recording address signals is superior in that it can accurately detect a predetermined information block, but it has the disadvantage that the equipment is complex and expensive.5Also, the latter method of detecting silent periods Although this method is superior in that it does not complicate the device, it has the disadvantage that it is difficult to distinguish between silent periods between songs and silent periods within a song.

Therefore, the object of the present invention is to record continuous PCM data in series.
An object of the present invention is to provide a PCSt signal reproducing device that can easily and accurately detect between blocks of a signal.

In order to achieve the above object, the present invention records a plurality of analog information blocks serially and continuously using PCM signals with spaces between blocks, and from a recording medium in which a constant PCM number is recorded in the spaces between blocks. a reproducing means for reproducing a signal; a digital-to-analog converter for converting a reproduced digital signal obtained from the reproducing means into an analog signal; and a detection circuit for detecting the constant PCM signal at a stage before the digital-to-analog converter m6. and has
The present invention relates to a PCM signal reproducing device characterized in that the constant PCM signal is detected in the state of a digital signal.

According to the above invention trap, there is a constant PCM in the inter-block space.
Since the signal is recorded and detected before the digital-to-analog converter, the interblock space can be detected accurately regardless of noise. Note that by detecting spaces between blocks, it becomes possible to cue or search information blocks.

Embodiments of the present invention will be described below with reference to the drawings.

First, referring to FIG. 1 showing the recording section of a PCM recorder playback device using a VTR according to the present invention, one input (1
) When an analog signal such as an audio signal is input to the sample and hold circuit 12), the analog signal is sampled and held at a predetermined sampling rate determined by the clock signal provided from the clock signal generator 131. . Since the sample and hold circuit (2) is connected to an analog-to-digital converter, that is, an A-D converter (4),
The sampled and held analog signal is converted to a digital signal.

The digital signals are output in parallel from the A-D converter (4), but are arranged in series by the scratch pad memo 151 of the output stage of the A-D converter and the parallel-to-serial converter (6). The PCM signal will be sent. The writing of the PCM signal into the memory (5) is performed first to next by addressing by the write-in address circuit (8).

The start of data stored in the memory (5) is performed by address designation by a start-up address circuit (9).

Parity check circuit α provided in branch circuit (7)
(it'ri,, form the parity bits of the data,
This circuit applies f'L to the parallel-to-serial converter (6). Therefore, the parallel-to-serial converter (6) outputs a PCM number with a parity bit attached.

Output of parallel-serial converter (6) and N-period signal circuit (1) 1
Since the output is connected to the output of the resistor q through the resistor 03), the PCM signal receives the large section synchronization signal (vertical synchronization signal) and the small section synchronization signal given from the synchronizer code circuit port 1). Signal (frame synchronization signal) is added nl e.g. "1" 0
This is a composite PCM signal with a three-value configuration consisting of "-1".

Such a composite PCM signal is processed by an FM modulation circuit (141
, recording amplifier circuit C19, magnetic head 06)
FM is recorded on magnetic tape ■ by TR (17I).

To explain the recording method in more detail, a plurality of songs A5, A2, A,
・・・・・・・・・Place A7 with tape a as shown in Figure 2.
Space between blocks is 13°~B on one side.
In order to perform continuous recording in series by providing 6 channels, a (1) quaternary analog signal is sent to the input signal file in correspondence with the song arrangement shown in FIG. The analog signal is converted into a PCM signal of 13 bits per word including a parity bit, as shown in FIG. 3, for example. In terms of waveform, if there are consecutive silent periods within the five songs that are a combination signal of "0" and "1" as shown in Figure 4, theoretically the PCMfu number will be "0". It is supposed to be a combination, but in reality, due to noise etc., it is not only "0", but the space between 5 songs where 11" appears in the small digit area corresponding to low level noise etc. Also in (B,) to (B,), the PCM signal corresponding to noise is recorded in n recorded by the conventional method.

However, in the present invention, the inter-song spaces (B,) to (B6)
Correspondingly, an output switch is sent from the inter-musical space signal input line OgJ, and the A-D converter (4) is digitally muted, making it independent of the input analog signal.

The A-D converter (4) outputs a digital signal as shown in FIG. 5, which corresponds to the fully operational level. Therefore, a digital signal representing a complete zero (C) is recorded in the inter-track spaces (B, ) to (B6) of the magnetic tape (A).

FIG. 6 shows a playback device that accurately detects between pieces of music (between information blocks). If a signal is detected from the magnetic tape (2) recorded by the apparatus shown in FIG.
A frequency signal of 5.4 MHz is obtained corresponding to @1'' of the signal, and 4.6 MHz corresponding to 10'' of the PCM signal.
A frequency signal of MHz is obtained, and a signal of 3.8 MHz is obtained corresponding to the synchronization signal. The FM wave detected by the magnetic head Qυ is amplified by the regenerative amplifier circuit ■ and then F
Demodulated by the M demodulation circuit Q3, for example, a 3-value composite P
This becomes the M signal.

The dropout detection circuit (24) is connected to the FMfN adjustment circuit (24).
3, and detects a drop in the level of the reproduced signal, that is, the reproduced FM wave, as a dropout. The data separated by the signal separation circuit connected to the FM multiple DA circuit (c) is sent to the scratchpad memory (b).

Also, the main sync signal (vertical sync signal) is separated by the sync signal separation circuit connected to the FM'1% tone circuit.
The small section synchronization signal (frame synchronization signal) is sent to the write address circuit 9 and used to control data loading into the nl memory α). The PCM signal output from the signal separation circuit (c) is also applied to a parity check circuit, where a parity check is performed. Then, only when a parity error occurs, an output is generated from the check circuit, and this is sent to the memory (A) through the OR[O1 path α].
The memory (2) indicates that the address is an error.
GK will be remembered. Since the output of the dropout detection circuit c2+1 is also input to the OR circuit 2, even when a dropout is detected, the fact that the address is an error is stored in the memory @. Data is read out from the memory wire in wide units based on address designation by the read address circuit Gυ. At this time, the error detection circuit (3
21 is provided, so that when an error is detected, the error compensation circuit operates to perform error compensation. The error-compensated data is converted into an analog signal by the DA converter, and an analog signal corresponding to the analog signal applied to the input terminal +11 is output from the output terminal.

In the device of this embodiment, the inter-musical spaces (B, ) to (B6)
Instead of being detected by a silent analog signal, the song interval detection circuit (2)K detects it digitally. That is, since the song interval detection circuit (b) is connected before the D-A converter,
A digital signal is input here.

The inter-song detection circuit (b) K detects the all-zero level digital signal shown in FIG. 5 recorded in the inter-song spaces CB, ) to (B6) in FIG. When the above results are obtained continuously, it is considered as an inter-song interval. Even if there is a silent period during a song, the digital signal will not become zero continuously due to trap noise as mentioned above, and the silent period within the song and the silent period between songs can be clearly distinguished. It can be detected separately. The output of the song interval detection circuit (b) is given to the song interval notification device or control circuit, and is used for cueing, automatic search, etc.
Ru.

As is clear from the above, according to the present invention, it is possible to easily and reliably detect intervals between songs (between information blocks).

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be further implemented. For example, as shown by the dotted line in Figure 1, zero PCM
A signal generator 0!1 is installed, and the space between songs (B,
) to (B6), the output of the A-D converter (4) is cut off, and instead of this, the zero PCM signal generator 09 generates a zero PCM signal as shown in FIG. This may be recorded on magnetic tape (a), or it may be recorded on a magnetic tape (a).
The present invention is not limited to CM recording, but can also be applied to recording PCM signals in bits on a recording medium such as a video disc. Further, the PCM signal to be recorded between songs is not limited to the signal shown in FIG. 5, but may be a fixed PCM signal in another form.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a PCM recording device according to an embodiment of the present invention, FIG. 2 is a plan view of a magnetic tape showing the arrangement of information blocks, and FIG. 3 is an explanatory diagram showing data *a:.
FIG. 4 is a waveform diagram of a PCM signal, FIG. 5 is a waveform diagram of an inter-song PCM signal, and FIG. 6 is a block diagram showing a PCM reproducing apparatus. In the symbols used in the drawings, (4) is an A-reverse converter, (181 is an inter-musical space signal input line, and G9 is
is a zero PCM signal generator, and G4) is a song interval detection circuit.

Claims (3)

[Claims] (1) reproducing means for serially and continuously recording a plurality of analog information blocks using PCM signals with inter-block spaces, and reproducing signals from a recording medium on which a certain PCM signal is recorded in the inter-block spaces; a digital-analog converter for converting the reproduced digital signal obtained from the reproduction means into an analog signal; and a digital-to-analog converter for converting the reproduced digital signal obtained from the reproduction means into an analog signal;
1. A PCM signal reproducing device, comprising a detection circuit for detecting a CM signal, and detecting the certain PCM signal in the state of a digital signal. (2) The PCM signal reproducing apparatus according to claim 1, wherein the information block is an audio signal block. (3) The PCM signal reproducing device according to claim 1 or 2, wherein the constant PCM signal is a PCM signal representing a complete zero level.