JPH0225200B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a PCM recording and playback device, and an object of the present invention is to provide a PCM recording and playback device that does not have any movable mechanical parts and can easily set and change the length of recording and playback times. It is about providing. The tape recorder is currently the most popular recording/playback device. It is well known that a tape recorder is a device that faithfully records and reproduces audio signals, but on the other hand, the main part of the tape recorder is a complicated movable mechanism, which can cause problems with the movable mechanism, the head, the tape, etc. Once this happens, the fidelity of recording and playback deteriorates, and in some cases, it stops functioning altogether. In a tape recorder, controlling the tape speed is important, so it must be said that it is impossible to change the length of the recording/playback time, especially to shorten it, by adjusting the tape speed. In order to shorten the recording and playback time, some tape recorders have been developed that use a method that cuts out a certain portion of the signal within a certain sampling time from recording and playback, but this method is complicated and difficult, making it expensive. do not have. The present invention relates to an epoch-making recording/playback device that eliminates the above-mentioned drawbacks, namely, the drawbacks in terms of maintenance and recording/playback time seen in conventional recording/playback devices. The present invention relates to a PCM recording and playback device that does not have a PCM recording and playback time and can easily set and change the length and shortness of the recording and playback time. The present invention provides a recording section having a semiconductor storage device for storing digital information obtained by converting an audio analog signal outputted from an audio-to-electrical quantity converter into a digital signal, and reading out the information stored in the semiconductor storage device. Consists of a playback section that plays audio.
In the PCM recording/playback device, the recording section is configured to digitally record the analog signal for a time corresponding to the pulse width of the pulse signal, based on a pulse signal that is generated periodically and whose pulse width can be arbitrarily changed. The present invention is characterized by comprising means for preventing information from being stored in the semiconductor memory device. The PCM recording and reproducing apparatus according to the present invention will be described in detail below. Figure 1 shows the state of the audio current within a certain time T. Time T is further divided into n equal parts (n = 8 in Figure 1), and a short time δ (=T/
The result of sampling the audio current every n) is the first
It is a table. Furthermore, Table 2 shows the results of converting Table 1 into digital signals. Figure 2 shows the basics of PCM recording and playback equipment.

【table】

[Table] This is a configuration diagram, where 1 represents the recording section and 2 represents the playback section. After the audio signal is input to an audio-to-electrical quantity converter 3, typically a microphone, the signal is sent to a pulse amplitude modulator 4 together with a sampling pulse from a sampling pulse generator 10, where it is pulse amplitude modulated. . This is an example of a signal in which the pulse at every δ time in FIG. 1 is pulse amplitude modulated. The output from the pulse amplitude modulator 4 is supplied to the AD converter 5 and converted into a digital signal, an example of which is shown in Table 2 above. The digital signal from the AD converter 5 is input to a storage device 6, typically a semiconductor memory, to complete the recording. The reproduction section 2 is
It is configured to undergo the reverse process of the recording section 1, and first, the signal from the storage device 6 is input to the DA in synchronization with the sampling pulse from the sampling pulse generator 11.
Output to converter 7. The DA converter 7 obtains a pulse amplitude modulated signal, and this signal is sent to the demodulator 8.
After demodulating the signal, the signal is supplied to a sound generator 9, typically a speaker, to generate reproduced sound. The above is the basic configuration of the PCM recording and playback device.In the PCM recording and playback device according to the present invention, in the above basic configuration, the amount of audio digital signals stored in the semiconductor memory can be changed. By doing so, it is possible to set and change the length of audio recording time that can be stored in a semiconductor memory having a predetermined storage capacity. A specific example will be described below. A certain portion of the input audio current signal, for example in FIG. 1, a 20% portion of the audio current signal within a certain time T, in FIG.
Input audio current signals within 0.8T to T time are excluded from recording and playback. This consists in excluding the signals at (n-1)δ and nδ in Tables 1 and 2. An example of how to exclude from recording is:
In the recording section 1 in FIG. 2, a recording signal and a signal having a pulse width of the excluded range time are transmitted through a simple gate circuit. For example, the width of the exclusion target range can be adjusted using 20
% or 10% can be easily determined by changing the pulse width of the signal indicating the excluded portion. The PCM recording/playback device according to the present invention cuts a part of the audio signal as described above, and during a certain recording, for example, the 0.8 to T portion within the time T is repeatedly excluded as shown in Fig. 1. Naturally, the excluded portions will not be recorded or played back.
However, as long as the exclusion remains within a certain range,
It has been experimentally confirmed that there is no problem with normal recording and playback. To exclude audio signals within a certain period of time from recording and playback, in addition to the method of excluding them at the time of recording as described above, it is possible to perform recording normally, that is, to record all the audio, and to exclude certain signal parts only during playback. There are ways to exclude it. In this case, the second
When outputting a signal from the storage device 6 shown in the figure, the address in the storage device of the storage device signal is repeated, and some
Exclude signals from playback by skipping some parts. When recording, record normally,
This method of cutting out a certain part of the audio only during playback is useful for understanding changes in the excluded range and the corresponding changes in the playback audio, but this method of excluding part of the recording during recording is , the capacity of the storage device can be saved, whereas the former method has the disadvantage that capacity cannot be saved. Therefore, in order to save space, it is preferable to first know the size of the appropriate exclusion range by excluding data during playback, and then perform exclusion from the time of recording. The PCM recording and playback device according to the present invention is a solid-state type recording and playback device that does not have any movable mechanical parts that are likely to cause failures, as described above, and is also capable of changing the amount of audio digital signals stored in the semiconductor storage device. By doing so, it is possible to change the length of time that a storage device with a predetermined storage capacity can record, making it possible to extend the recording time of audio with limited storage capacity, which makes it possible to Recording and playback devices such as tape recorders have recording and playback functions that are difficult to implement.

[Brief explanation of drawings]

Fig. 1 An example of audio current at time T, Fig. 2 PCM
Basic configuration diagram of the recording and playback device, 1: Recording section, 2: Playback section, 3: Audio-electrical quantity conversion section, 4: Pulse amplitude modulator, 5: AD converter,
6: Storage device, 7: DA converter, 8: Demodulator,
9: Sound generator.

Claims (1)

[Claims] 1. A recording section having a semiconductor storage device that stores digital information obtained by converting the audio analog signal output from the audio-electrical quantity converter into a digital signal, and reading out the information stored in the semiconductor storage device and reproducing the audio. In the PCM recording and playback device, the recording unit records the analog signal for a time corresponding to the pulse width of the pulse signal, based on a pulse signal that is generated periodically and whose pulse width can be arbitrarily changed. 1. A PCM recording and reproducing device, comprising means for preventing digital information corresponding to a signal from being stored in the semiconductor storage device.