JPS59116907A - Automatic setting method of recording level - Google Patents

Abstract

PURPOSE:To enable automatic setting of an optimum recording level with the less tape used in the case of recording information signals on the tape by recording the recording signal of a head in the state of stopping the tape prior to recording, reproducing said signal and using the reproduced output thereof. CONSTITUTION:A tape which is stopped is subjected repeatedly to recording and reproducing with heads HA and HB at every one rotation by means of a signal SW2 and a switch circuit 7 while the heads HA and HB are in the state of stationary rotation. When a test signal is supplied from a circuit 16 to a gain control amplifier GCA5, a gain control signal SC is supplied to the amplifier 5 and the head HA performs scanning. The gain is linearly changed within a 180 deg. period. The signal SR is recorded with the head HA in the period TA within the period TR at every other one rotation. The tape is put into the reproducing state by the circuit 7 in the next period TPB and a reproducing signal SPB is obtd. with the head HA in the period TA. The level is detected with a detecting circuit 17 and is supplied to a controller 9. The recording and reproducing of the test signal at every one rotation are accomplished several times. When the max. of the detected output is detected, the control signal SC is set at that point.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for automatically setting an optimum recording level for a head when recording information signals such as audio signals on tape.

Background Art and its Problems For example, when recording audio signals with a tape recorder, setting the signal recording level is very important in order to obtain a good reproduction signal. especially,
Even in PCM tape recorders in countries where audio signals, etc. are converted to PCM and recorded on magnetic tape, incorrect setting of the signal recording level can lead to an increase in the error rate of PCM data. Setting the signal recording level is essential.

This optimal recording level is determined by the magnetic head and the magnetic tape, and especially now that many types of magnetic tapes with different magnetic materials and characteristics can be used, the optimal recording level is set between the head and the tape. There is a need to. Therefore, in the case of a conventional fixed head audio tape recorder, the signal is recorded once while the tape is running while changing the recording level, and then the signal is played back and the recording level is set based on the reproduced signal! 5K
A method is adopted in which the optimal recording level is automatically set for both the head and tape.

However, in this method, at least several seconds worth of unnecessary test signals for setting recording t/pel must be recorded on the tape, which wastes the tape.

By the way, although most conventional audio tape recorders are of the fixed head type, rotary head type audio tape recorders are also being considered. This rotating head type has the advantage that recording density can be increased by the so-called azimuth recording method, and since a rotating head is used, signals can be recorded and reproduced even when the tape is stopped.

OBJECTS OF THE INVENTION The present invention is a rotary head type tape recorder that takes advantage of the features of the rotary head type to automatically set the optimum recording level while using as little tape as possible.

SUMMARY OF THE INVENTION This invention provides a method for recording an information signal on a tape by a rotary head, and recording and reproducing the recorded signal by changing the recording signal of the head in a state where the tape is stopped prior to recording. This is an automatic recording level setting method that sets the optimal recording level for the tape and head based on the playback output.The method records a test signal while the tape is stopped, and then plays it back to determine the recording level. Since the settings are made, there is almost no wastage of tape.

Example Hereinafter, an example of this invention will be explained with reference to the drawings.

The example shown below uses a rotating head device in which two rotating magnetic heads I (A, HB) are mounted at 180° angular intervals, and the tape is wound diagonally around the guide drum over the 180° angular range. The audio signal with P
This is an example of recording as a commercial.

FIG. 1 shows an example of this, in which an audio signal passes through an input terminal (1), is converted into a digital PCM signal by a converter (2), and is supplied to an encoder (3). This encoder (3) blocks the PCM audio data and adds an error correction code.

The output signal of this encoder (3) is sent to the switch circuit (4)
, gain control amplifier (5), recording amplifier (6), and switch circuits (7) and (8).
B is alternately supplied and recorded as diagonal tracks on the tape. Here, the switch circuit (7) is for recording/playback switching, and the switch circuit (8) is for heads HA, H.
This is for switching B. These switch circuits (7) (
8) are switched by switching signals sw1 and sw2 from a controller (9) having, for example, a microcomputer. That is, the switch circuit (7) is switched from the state shown in the figure during recording to the state opposite to the state shown during playback, and the switch circuit (8) is switched from the state shown in the figure during recording to the state opposite to the state shown in the figure during playback. Each head temperature and HB are switched for each section TA and TB in contact with the tape.

During playback, signals taken out alternately from the head and HB are supplied to the playback amplifier αQ through the switch circuits (8) and (7), and are subjected to waveform shaping and the like to play back digital signals, which are then sent to the switch circuit 0. ■ Via the decoder (
6), and the error correction code is used to perform error correction, etc., and the signal is returned to the original PCM signal. This PC
The M signal is then supplied to the converter (C) and converted back into an analog audio signal, which is then led out to the output terminal α through the amplifier α.

The switch circuit (4) and α are switched between normal recording and reproduction and when setting the recording level) and are also controlled by a switching signal SW1 from the controller (9).

In this example, prior to recording as described above, the optimum recording level is set as follows.

Although not shown, for example, when the recording level setting switch is turned on, the tape is stopped and the rotating heads HA and HB are rotating at a steady rotation speed.
The switch circuits (4) and α) are switched to the state shown in the figure by the signal Sw1 from the controller (9). Also,
According to the signal Sw2, the switch circuit (7) rotates the rotating head HA.
, HB are switched alternately every rotation. Tsumashi,
Recording and reproduction are alternately repeated every rotation. Also,
The switch circuit (8) is fixed, for example, in the state shown in the figure (on the head recumbent side).

Then, at this time, a test signal of a constant frequency, for example, from the test signal generation circuit OQ is supplied to the gain control amplifier f (5) through the switch circuit (4). At this time, a gain control signal SC is supplied from the controller (9) to the gain control amplifier (5), and the gain changes from, for example, a low value to a high value within the 1800 angle range period in which the head scans the tape. Changed linearly. In other words, the recording level is changed. This recording level changed signal SR is used to switch the switch circuit (7) to the state shown in the figure during the first half period during which the head advance scans the tape during every other rotation period TR shown in FIG. At the TA, the data is supplied to the head and recorded on the tape. Then, in the period TPB every other revolution following the period TR, the switch circuit (7) is in the reproducing state in the opposite state to the state shown in the figure, so that the rotational head advance in the first half of the period TPB is During the upper scanning period TA, a reproduction signal SPB of the recording signal SR is obtained by this head advance, and this is transmitted to the level detection circuit α via the reproduction amplifier αQ and the switch circuit α.
It is supplied to η and the level is detected. and) the detection output is supplied to the controller (9) and one of the test signals is
Recording/reproduction is performed for each rotation, for example, ten times, and the point at which the level detection output becomes maximum is detected, and the gain control signal SC is set to correspond to that point.

In this way, the optimum recording level for the head-advance tape can be set.

Next, the switch circuit (8) is switched to a state opposite to that shown in the figure as necessary, and the head H is switched on in the same manner as described above.
The optimum recording level for tape B is set in each latter period 'rn of the period TR+TPB for each rotation.

After the optimal value of the recording level is determined as described above,
When the record button is pressed, recording of the audio signal begins by transporting the tape from the tape stop position.

As described above, according to the method of the present invention, the optimal recording level can be set while the tape is stopped, and recording can be started from that position, so there is no waste of tape.

FIG. 3 is a block diagram for explaining the present invention in detail. In this example, the optimum recording level is selected at the point where the pb ratio of the PCM signal is minimized.

That is, in this example, one ROM (1 barrel) is provided for generating a test PCM signal, and this test PCM signal is used as a test signal to be recorded and played back when the tape is stopped. ), the test from the ROMα barrel) After the PCM signal is added with an error correction code in the encoder (3), it is sent to the gain control amplifier (5).
through the recording amplifier (6) to the rotating head island or HB, and for playback, the decoder (6)
, an error in the data is detected, and the detection signal E
R (error flag) is supplied to the controller (9). The gain control signal SC from the controller (9) is set to a value that minimizes data errors in the decoder (6).

In the above example, the gain control signal SC is changed within the scanning period of each head on the tape, but the gain control amplifier may be changed stepwise for each rotation.

Furthermore, it goes without saying that the present invention is not limited to the case where an audio signal is recorded as PCM as described above, but can also be applied to a case where an analog audio signal is recorded as it is, or another information signal is recorded using a rotary head.

Effects of the Invention As described above, this invention takes advantage of the features of the rotating head type recording machine and allows the optimum recording level to be set while the tape is stopped. There is no waste.

Moreover, since the rotary head normally rotates at a high speed of 30 rpa, even if recording and reproduction are repeated, for example, ten or more times when setting the recording level, the time required is very small.

In other words, the time required to set the optimum recording level is extremely short.

[Brief explanation of drawings]

FIG. 1 is a system diagram for explaining an example of the method of this invention.
FIG. 2 is a time chart for explaining the method, and FIG. 3 is a system diagram for explaining another example of the method of this invention. ) IA, HB is the rotating head, (5) is the gain control amplifier, (9) is the controller, αQ is the test signal generation circuit,
The α frame is a ROM for PCM signal generation. Figure 1 Figure 2 Figure 3!

Claims (1)

[Claims] When an information signal is recorded on a tape by a rotating head, the recording signal of the head is changed and recorded while the tape is stopped prior to recording, and it is also played back, and based on the playback output, An automatic recording level setting method that sets the optimal recording level for the tape and head.