JPH026147B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a PCM (Pulse Code Modulation) recording/playback device, and in particular to a high-precision AD (Analog-Digital) converter suitable for IC (Integrated Circuit). and a PCM recording and playback device equipped with a DA (digital-to-analog) converter.

[Background of the invention]

A PCM recording and playback device converts an analog audio signal into a digital value via an AD converter, records it on a recording medium such as a magnetic tape, extracts this recorded content, and converts it back to the original analog audio signal via a DA converter. This is a device that has all or some of the functions for playing back music. This will be explained in more detail with reference to the block diagram shown in FIG. In Figure 1, W above the broken line represents the recording system, and R below the broken line.
indicates a reproduction system, and 1 indicates a recording medium, such as a magnetic tape or a disk. The input analog audio signal 11 is sent to the sampling/holding circuit 13 via the low-pass filter 12, where its amplitude is extracted and held at regular time intervals by the sampling pulse SP.
The AD converter 14 converts the signal into a digital signal, and the next signal processing unit 15 adds error detection codes and data synchronization codes, interleaves (reorders the data), and sends it to the recording amplifier 16 to be sent to the recording medium. 1 is recorded. When reproducing the recorded content, the synchronization processing circuit 22 is transmitted via the reproduction amplifier 21.
The data is read out with bit and frame synchronization, and after code error processing and jitter absorption are performed in the next signal processing section 23, the data is read out in the AD converter 24.
The input analog audio signal is restored by the low-pass filter 25 and output as 26.

The AD converter 14 and DA converter 24 in this PCM recording and reproducing apparatus require converters of approximately 14 to 16 bits from the standpoint of realizing high-fidelity recording and reproduction. In order to realize PCM recording and playback equipment economically, it is necessary to incorporate the above-mentioned high-precision converter into an IC. It is extremely difficult to integrate AD converters and DA converters into ICs. In order to create a converter that can meet the above requirements, the present inventors first developed an error correction method that reduces the effects of variations in component elements, temperature fluctuations, changes over time, etc. by correcting the nonlinear errors of the converter. AD converter with circuit (patent application 1972)
-124514) and a DA converter with an error correction circuit (Japanese Patent Application No. 1982-8231). However, in order to incorporate this proposed converter into a PCM recording and playback device and fully utilize its performance, it is necessary to operate the error correction circuit at certain intervals.

[Purpose of the invention]

An object of the present invention is to provide a means for generating a correction start signal to the error correction circuits in a PCM recording and playback device in which AD and DA converters are equipped with error correction circuits, thereby achieving high accuracy. Moreover, AD and DA enable integration into ICs.
To provide PCM recording and playback equipment with converter.

[Summary of the invention]

In order to achieve the above object, the features of the present invention are as follows:
At least one of the AD converter and the DA converter is equipped with an error correction circuit and a correction start signal generation means for supplying a correction start signal to these error correction circuits, and this correction start signal generation means is provided in the error correction circuit. The object of the present invention is to provide a means having a function of detecting with a logic circuit that the recording/playback content is silent during the required correction time and using this detection output as a correction start signal.

[Embodiments of the invention]

The present invention will be explained below with reference to the drawings.

First, for convenience of explanation, one embodiment of the present invention regarding a reproduction system will be described with reference to FIG. In FIG. 2, 2 is the correction start signal, 3 is the correction period,
It is a gate circuit that cuts off the output of the DA converter 24, 4 is a generation circuit that generates the correction start signal 2, and the other symbols are the same as in FIG.
The first method of generating the correction start signal 2 is to generate the correction start signal 2, for example, if a performance song is recorded on the recording medium 1, the time T required for correction (usually 10 to 100 milliseconds) between or within the performance song. This method detects that there is no sound in the recorded content during the period of 30 minutes, and makes corrections during this silent period. To be more specific, originally,
If the correction is performed when the power is turned on or when the system starts operating, the correction of the AD converter and DA converter will be completed at that point, ensuring accuracy. However, if left as is for a long period of time, changes in temperature etc. will cause a slight deviation from the initial setting value, resulting in poor accuracy. However, this deterioration in accuracy does not occur rapidly within a short period of time. In practice, there is no problem with no correction for 30 minutes to 1 hour, and within this amount of time there is usually a silent period between songs, etc.
If this silent period is detected and corrected,
This means that sufficient accuracy can be ensured even if there are few silent periods or if there are many locations to be corrected. A specific example of the circuit configuration is shown in FIG. In FIG. 3, 23' is a shift register of the partial circuit of the signal processing section 23 that stores the digital audio signal of the correction period T; 41 is a digital comparator for detecting that the digital audio is silent; 42 is a shift register that stores the comparison result for the correction period (if there is no sound, the high level is "1"), and 43 is a state that there is no sound during the correction period T, that is, the contents of the shift register 42 are all "1".
This is an AND circuit that outputs a correction start signal 2 when it detects that. According to the circuit configuration shown in FIG. 3, if the silent period continues for the period T, a signal of level "1" is output from the AND circuit 43, and this can be used as a correction start signal.

A second method for obtaining the correction start signal is to generate the correction start signal in conjunction with a power switch or a drive switch necessary for reproduction. This method has a simpler configuration than the first method, but
1 correction per tape (or 1 disk)
Therefore, in the case of long-term recording media, corrections will be made approximately once every few hours, and compared to the first method, the DA converter will have higher stability. You will need it. A third method for obtaining a correction start signal is to record a correction start signal or a silence signal that can be used as a correction start signal on a recording medium in advance. in particular,
Methods include (1) recording the above signal between each performance piece; (2) assigning an address between each performance piece, such as the name of the performance piece or performance number, and using that address signal as the correction start signal. . For example, if you record the above signal between each performance song, you can record it for each performance song (every few minutes to several tens of minutes).
This eliminates the need to provide a special circuit for generating a correction start signal. As described above, each of the first to third correction start signal generation means for the reproduction system has its own features and is effective.

Next, the fourth embodiment of the present invention regarding the recording system will be described.
This will be explained using figures. In Figure 4, 13,1
Reference numerals 4, 15, and 16 designate a sampling/holding circuit, an AD converter, a signal processing section, and a recording amplifier, respectively, which have the same functions as those in FIG. 1 and digitally record the input analog audio signal on the recording medium 1. 5 is a correction start signal, and 6 is a signal for silent addressing, etc. The first method for obtaining the correction start signal 5 is to generate the correction start signal 5 in conjunction with a power switch or a drive switch necessary for recording, similar to the second method for the reproduction system. The second method uses the correction start signal necessary in the above-mentioned reproduction system or the third
In this method, when recording the silent addressing signal described in the above method, the signal is shared as a correction start signal for the recording system. Both of the above two methods are effective when employed in the correction start signal generating means, as in the case of the reproduction system.

〔Effect of the invention〕

As described above, according to the present invention, a PCM recording and playback device having an AD and DA converter with an error corrector is equipped with a means for generating an error correction start signal. It is possible to realize a highly accurate and economical PCM recording and playback device that can be integrated into an IC.

[Brief explanation of drawings]

Fig. 1 is a block diagram for general explanation of a PCM recording and playback device, Fig. 2 is a block diagram of an embodiment of the present invention for a playback system, and Fig. 3 is a partially detailed diagram of Fig. 2. FIG. 4 is a block diagram of an embodiment of the present invention for a recording system. Explanation of symbols 1... Recording medium, 2, 5... Correction start signal, 3... Gate circuit, 4... Correction start signal generation circuit, 6... Silent addressing signal, 11...
... Analog audio signal, 12, 25 ... Low-pass filter, 13 ... Sampling holding circuit, 14 ... AD converter, 15, 23 ... Signal processing section, 24 ... DA converter, 41 ... Digital comparison vessel, 23', 42
...Shift register.

Claims (1)

[Claims] 1. A PCM that converts an analog audio signal into a digital value via an AD converter, records it on a recording medium, extracts this recorded content, and reproduces it into the original analog audio signal via a DA converter. The recording and reproducing apparatus includes an error correction circuit for at least one of the AD converter and the DA converter, and correction start signal generation means for supplying a correction start signal to these error correction circuits, and the correction start signal generation means. A PCM recording device characterized in that the means includes a logic circuit for detecting that the recording/playback content is silent during the correction required time in the error correction circuit, and uses the output of the logic circuit as a correction start signal. playback device. 2. In the device according to claim 1,
The correction start signal generating means further has a function of generating a correction start signal in conjunction with the ON operation of the power switch of the recording and playback device or each drive switch for each recording and playback.
PCM recording and playback equipment.