JPS5942610A - Device for setting sound recording level in tape recorder - Google Patents

Abstract

PURPOSE:To set easily an optimum sond recording level, by making a reference signal pass through an attenuator which is transmitting a signal, varying it, sound-recording and reproducing it, deriving the maximum level for sound recording, and thereafter, detecting a peak level of a source input signal so that it becomes equal to the maximum sound recording level. CONSTITUTION:Simultaneously with start of a test, changeover switches SW1, SW2 are set to the side (b), and a device is set to a sound recording and reproducing mode. Subsequently, a reference signal Sr is attenuated, is corrected by a sound recording equalizer 4 through a sound recording amplifier, is supplied to a sound recording head 5, and is sound-recorded in a magnetic tape 7. This sound-recorded reference signal is reproduced by a reproducing head immediately, is corrected by a reproducing equalizer 9, and a DC level VR passing through a reproducing amplifier 10 is converted by an A/D converter 14 and is inputted to a controller 6. An input data in this case is stored as the maximum sound recording level of an available tape. Thereafter, the changeover switches SW1, SW2 are switched to the side (a), a source signal Si is inputted to a level detector 13, a peak level of several seconds is detected, this detected level is converted by the A/D converter 14 and is inputted to the controller 6, and a sound recording level is set to an optimum value so as to become equal to the maximum sound recording level.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording level setting device for setting an optimum recording level according to the magnetic tape used in a tape recorder.

With conventional tape recorders, when setting the recording level,
You can do this by manually controlling the volume while watching the level meter, or if you have an automatic recording level setting device, you can always automatically set the recording level to a constant level regardless of the type of magnetic tape being used. It was put away.

Therefore, in the former case, the operation requires skill and it is difficult to set the optimum recording level, while in the latter case, although the operation is not cumbersome, it is difficult to set the optimum recording level according to the type of tape. Therefore, there was a problem that, for example, the characteristics of metal tapes etc. could not be fully brought out.

The present invention was made in order to solve such problems, and an object of the present invention is to make it possible to easily set the optimum recording level according to the characteristics of the magnetic tape used.

Therefore, the recording level setting device according to the present invention includes an attenuator in the signal transmission path to the recording head, records a reference signal at a constant frequency and a constant level while varying it through the attenuator, and then plays it back. The level when the maximum is reached is the maximum recording level, and then the peak level of the signal that has been passed through the source input with the attenuation amount of the above-mentioned attenuator set to 0 is detected and compared with the previously detected maximum recording level. The two levels are made equal, and the difference in level is used as the attenuation amount of the attenuator to automatically set the optimum recording level.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, 1 is a source input terminal, and 2 is an attenuator, which is provided in the signal transmission path from the source input terminal 1 to the recording head 5 via the recording amplifier O and the recording equalizer 4, and is digitally controlled by the controller 6. The resistance value is changed to attenuate the signal that passes through it.

7 is a magnetic tape, 8 is a playback head, and the playback signal is sent to a detector 1 via a playback equalizer 9 and a playback amplifier 10.
Enter 1. This detector is provided to rectify the reproduced signal and convert it to a DC level.

12 is a reference signal generator with a constant frequency (for example, IK
Generates a reference signal with a constant level (Hz sine wave).

A level detector 13 detects the peak level of the source signal that has been attenuated through the attenuator 2 for several seconds. 14
is an A/D converter that converts the signal level detected by this level detector and the above-mentioned wave detector 11 into digital data and inputs it to the controller 6.

SWI and SW2 are interlocking changeover switches.

The first changeover switch SW switches the signal input to the attenuator 2 from the reference signal Sr to the source signal Si, and the second changeover switch SW2 changes the input to the A/D converter 14 to the detector 11. It serves to switch from the output to the output of the level detector 13.

In this embodiment configured in this way, at the same time as the eggplant 1-start, the 1st. Second changeover switch SWI, S
As shown in the figure, move W2 to side b to cellar 1, and set the tape recorder to recording/playback mode.

Then, the reference signal Sr generated by the reference signal generator 12 is attenuated through an attenuator 2, passed through a recording amplifier (such as a Dolby amplifier), corrected by a recording equalizer 4, and supplied to a recording head 5 to be recorded on a magnetic tape 7. Record.

This recorded reference signal is immediately played back by a playback head, corrected by a playback equalizer 9, passed through a playback amplifier 10, and inputted to a detector 11, where it is rectified and converted to a DC level.

This DC level Vr is converted into digital data by the A/'D converter 14 and input to the controller 6.

In this example, the resistance value, or attenuation amount, of the attenuator 2 is controlled by the 4-bit binary output from the controller 6, and the attenuation amount is maximum when the binary output is "0"(0000''). , r15J (1111″), the attenuation amount becomes zero.

Therefore, the controller 6 initially outputs a binary output of ``000''.
The reference signal Sr is recorded, and the value of the reproduced signal level Vr converted into digital data by an A/D converter is stored. Next, set the binary output to '0001', record in the same way, detect the level of the playback signal, and judge whether it is greater than the previous data. If it is greater, the binary output is sequentially recorded one by one. Increase the volume and repeat recording and playback.

As a result, the attenuation amount of the attenuator 2 gradually decreases from the maximum as shown in FIG. 2, and the reproduced signal level gradually increases as shown in FIG. 6. In addition, in FIGS. 2 and 6, binary output data is expressed as corresponding decimal data (
Displayed in decimal notation.

When the playback signal level becomes smaller than or equal to the previous data as in the case of binary output "8" in FIG. 3, the input data from the A/D converter 14 at this time is used to It is stored as the recording level and recording/playback operations are stopped.

After that, set the changeover switches swt and SW2 to a
side, the source signal Si from the source input terminal 1
is input to the level detector 13 through the attenuator 2, and the peak level for several seconds is detected.

The level detected by the level detector 13 is converted into digital data by the A/D converter 14 and input to the controller 6.

Thereby, the controller 6 adjusts the A/D converted detection level to be equal to the previously stored maximum recording level.
The amount of attenuation of the attenuator 2 is controlled by the 4-bit binary output, and the recording level is set to the optimum value for the tape used.

In this way, the recording level setting, which has conventionally been troublesome to operate, can be automatically set to take full advantage of the characteristics of the tape being used.

In addition, if the selector switches SWI and SW2 are configured using electronic analog switches and are automatically switched by the controller 6, the recording level can be changed completely automatically with just one touch operation to start the test. settings can be made.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention, and FIG.
3 and 3 are explanatory diagrams for explaining the operation of the embodiment shown in FIG. 1, respectively. 2... Attenuator 6... Controller 7... Magnetic tape 11... Detector 12... Reference signal generator 1... Level detector 14... A/D converter

Claims (1)

[Claims] 1. In a tape recorder, an attenuator provided in a signal transmission path to a recording head, a controller that digitally controls this attenuator according to input data, and a controller that controls the attenuator digitally in accordance with input data; a reference signal generator that generates a reference signal, a detector that detects the DC level of the playback signal played by the playback head when recording the reference signal, and a level detector that detects the peak of the source input attenuated by the attenuator. an A/D converter that converts the signal level detected by the level detector and the wave detector into digital data and inputs the digital data to the controller; a second changeover switch that changes the input to the A/D converter from the output of the wave detector to the output of the level detector in conjunction with the input side switch; After switching the second changeover switch to the signal side and the detector side, and recording and reproducing the reference signal to learn the saturation characteristics of the magnetic tape, turn the first changeover switch to the source side. The recording level setting device is configured to set a source input level adapted to the saturation characteristic by the controller by switching the second changeover switch to the input side and to the level detector side.