JPS6020199Y2 - tape recorder - Google Patents

Description

[Detailed explanation of the invention] This invention compresses and records the signal to be recorded, reproduces and expands the recorded signal, and gradually reduces the noise superimposed on the signal during this recording and reproduction process. The present invention relates to a tape recorder having a noise reduction system.

Generally, a tape recorder having this type of noise reduction system includes means for detecting the level of a signal to be recorded, means for compressing the signal according to the level detected by the means, and means for compressing the signal according to the level detected by the means. A recording/reproducing apparatus comprising means for recording, means for reproducing the signal thus recorded, and means for expanding the reproduced signal, and including the means for recording the signal and the means for reproducing the signal. I tried to obtain a signal with less noise superimposed in the system.

By the way, in a tape recorder configured like this,
If the pilot signal of the stereo FM tuner mixes with the signal to be recorded, the level of this pilot signal will cause
The degree of compression described above changes and the fidelity of the reproduced and expanded signal is lost.

For this reason, conventional devices are equipped with a filter that removes the pilot signal from the signal to be recorded, so that when compressing the signal as described above, the pilot signal is not included in the compressed signal. In addition, the pilot signal of the signal was also cut so that the influence of the pilot signal was exerted on the level of the signal that determined the degree of compression.

If such a filter is provided, the high-frequency components of the signal to be recorded will also be lost, so when recording and reproducing a signal that does not include the above-mentioned pilot signal, such as from a record, the high-frequency components of the signal to be recorded will be lost. will be lost unnecessarily.

In conventional apparatuses, a switch is provided to selectively bypass the filter to prevent unnecessary loss of high-frequency components of the signal to be recorded.

This switch is used to select whether or not to cut the signal in the frequency band corresponding to the pilot signal mentioned above from the signal to be recorded, and to select whether or not to operate such a noise reduction system. It is provided separately from the switch.

This invention prevents the degree of compression described above from changing depending on the level of the pilot signal without providing a switch that bypasses the above-mentioned one filter, thereby maintaining the fidelity of the reproduced and expanded signal. To provide a tape recorder which is capable of recording a signal in a frequency band corresponding to the above-mentioned pilot signal sufficiently to the extent that it does not interfere with the auditory sense, without causing loss of accuracy, etc. This is the purpose.

The gist of this invention, which is a distant relative of the above object, is to provide a means for detecting the level of a signal to be recorded, a means for compressing the signal according to the level detected by the means, and a means for compressing the signal according to the level detected by the means. A means for recording a compressed signal, a means for reproducing the signal thus recorded, and a means for expanding the reproduced signal, the means for recording the signal and the means for reproducing the signal. In a tape recorder designed to obtain a signal with less noise superimposed in a recording/reproduction system including The tape recorder is characterized in that it is configured such that at least the signal reaching the compression means can include the pilot signal.

An embodiment of this invention will be described below with reference to the drawings.

In the figure, reference numeral 1 is an input terminal for a signal to be recorded, and the signal to be recorded inputted from the input terminal is passed through a compression device (compressing means) 2 and a filter 4 for removing the pilot signal of the stereo FM tuner. is supplied to

The signal passed through the compression device 2 described above reaches an output terminal 3, and is recorded on a magnetic tape (not shown) by a magnetic head, as is well known.

The level of the signal passing through the filter 4 is detected by the level detector 5, and the compression device 2 is controlled according to the detected level, and the level of the signal passing through the compression device is determined by the level detector 5. It is compressed according to the level.

Reference numeral 6 is a switch for selecting whether or not to operate the compression device 2 described above.

As described above, this invention includes means for detecting the level of the signal to be recorded, such as the level detector 5, means for compressing the signal, such as the compression device 2, according to the level detected by the means, and known means of recording compressed signals;
A recording/reproducing system comprising a well-known means for reproducing the signal recorded in this manner and a means for expanding the reproduced signal, and a recording/reproducing system including a means for recording the above-mentioned signal and a means for reproducing the signal. In a cheap recorder designed to obtain a low-noise signal, a filter 4 is provided for removing a pilot signal of a stereo FM tuner from a signal leading to the above-mentioned signal level detecting means, and also leading to at least the above-mentioned compressing means. Since the signal path that passes through the compression means is not provided with a filter that removes the pilot signal so that the signal includes the pilot signal, the following effects can be obtained. .

In other words, there is no longer a need for a switch to bypass the filter for removing the pilot signal, and compared to a conventional device that is equipped with a filter that cuts the pilot signal of the signal passing through the compression device and a bypass through switch. It has the following characteristics:

(1) For signals with a frequency lower than the pilot signal, for example, a signal with a frequency of 15 KHz or less, which occupies the large part of the frequency components of music, substantially the same noise reduction effect as the conventional device can be obtained.

(2) For signals with a frequency of 15KHz or higher,
Although the noise reduction effect is reduced, noise at such high frequencies reduces the human auditory ability to detect noise due to the well-known Fletcher-Manson effect, etc. As for the noise reduction effect, the effect on auditory sensation is small.

(3) In general, in tape recorders, etc., the recording and playback characteristics of signals with a frequency of 15KH2 or higher largely depend on the performance of the magnetic head, magnetic tape, etc., and a 1 variation in frequency characteristics occurs in such high frequencies. Sometimes.

It is known that this 1 variation is doubled by the operation of noise reduction.

With this invention, there is virtually no noise reduction effect in the high frequency range, so the frequency characteristic is not doubled by one fluctuation as described above.

(4) When the signal to be recorded is passed through a filter for cutting the pilot signal as in the conventional device described above, unnecessary changes may occur in the timbre of the reproduced musical tone etc. due to the influence of the phase characteristics of this filter. It has been known.

To solve this problem, it is necessary to use an expensive filter with good group delay characteristics, such as a digital filter.

It is well known that the group delay characteristic of the filter used to remove the 19 kHz pilot signal affects musical tones below 7 to 8 kHz, and this means that the approximately 10 Hz rectangular wave that has passed through the above filter You can easily confirm this by recording it.

In this invention, since the signal passing through the compression device does not pass through the filter as described above, that is, the signal system is not provided with a filter for removing the pilot signal.
It is possible to record without sacrificing the group delay characteristics of musical tones as described above, that is, to reduce unnecessary changes in the timbre of the reproduced musical tones.

(5) In general, high-quality tape recorders such as open reel tape recorders often record and play back without operating a noise reduction system, and therefore the above-mentioned pilot signal may also be recorded and played back.

It is difficult to determine whether or not the above-mentioned pilot signal is included in the playback signal from such a tape recorder, so in conventional equipment equipped with a switch to bypass the pilot signal as described above, this switch is I often wonder whether I should turn it on and record, or turn it off and record.

This device does not have the above-mentioned switch and can reliably transfer musical tone signals even from the above-described tape recorder.

[Brief explanation of drawings]

The figure is a block diagram showing an embodiment of this invention. 2: compression device, 4: filter, 5 two-level detector.

Claims (1)

[Scope of utility model registration request] means for detecting the level of the signal to be recorded; means for compressing the signal according to the level detected by the means; means for recording the compressed signal; The present invention includes a means for reproducing the signal and a means for expanding the reproduced signal, so as to obtain a signal with less noise superimposed on a recording/reproducing system including the means for recording the signal and the means for reproducing the signal. In the tape recorder, a filter is provided to remove the pilot signal of the stereo FM tuner from the signal reaching the signal level detecting means, and the signal to be recorded is sent to the compressing means without passing through the filter. A tape recorder characterized in that it is configured to be supplied directly.