JPH0513111Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a recording and reproducing apparatus for television signals, and more particularly to a recording and reproducing apparatus that can display the state of harmonic distortion of a reproduced signal.

[Conventional technology]

Conventionally, this type of recording and reproducing apparatus records and simultaneously reproduces television signals, and uses the reproduced signal level shown on a display or the like as a reference for determining recording current.

[Problem that the invention attempts to solve]

However, in the conventional recording/playback device mentioned above,
Since the recording current is adjusted so that the RF signal level is maximized, there is a drawback that secondary distortion is not necessarily minimized. Furthermore, in direct FM recording of images, secondary distortion appears on the screen as moiré, resulting in a problem of deteriorating image quality.

[Means for solving problems]

The recording and reproducing apparatus of the present invention includes means for switching a part of the blanking period of the television signal to be recorded into a reference signal for detecting harmonic distortion and recording it on a recording medium when recording a television signal; means for reproducing the reference signal for detecting harmonic distortion, means for detecting a fundamental wave component and a second harmonic component from the reproduced reference signal for detecting harmonic distortion, and the detected fundamental wave component. and a second harmonic component, and means for displaying the ratio.

[Effect]

Therefore, according to the present invention, the degree of harmonic distortion of the reproduced signal can be displayed by extracting the fundamental wave component and the second harmonic component from the reproduced signal, calculating and displaying the ratio thereof. I can do it.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows a block diagram of an example in which the present invention is implemented in a magneto-optical disk system. In FIG. 1, an RF amplifier 1 receives a reproduced signal from a recording/reproducing head 16, amplifies it, and outputs the RF signal to bandpass filters (BPF) 2a and 2b. At this time, the bandpass filter 2a is tuned to the frequency of a harmonic distortion detection reference signal (hereinafter referred to as the reference signal), and the bandpass filter 2b is tuned to twice the frequency. Therefore, the output signals S1a, S1a, of each bandpass filter 2a, 2b
S1b passes through rectifier circuits 3a, 3b, sample and hold circuits 4a, 4b, and A/D converters 5a, 5.
A/D conversion is performed at b. These A/D converted signals S3a and S3b are then sent to input ports 6a and 6b.
input to the data bus through. Connected to the data bus are a central processing unit (CPU) 10 that performs calculations, a read-only memory (ROM) 9 in which control programs are written, and a random access memory (RAM) 8 that stores controlled data. As a result, output port 7 outputs the CPU
Data S4 representing the component ratio R of the fundamental wave and the second harmonic calculated in step 10 is outputted, passes through the D/A converter 11, the meter amplifier 22, and drives the harmonic distortion indicator 23. On the other hand, the pulse signal S5 from the tack pulse circuit 21 is input to the timing circuit 15, and is outputted as a clock c having a certain amount of delay time. Depending on the timing of this clock c, the switch 14 outputs the above reference signal.
Switch to pass S7. Thereby, the reference signal S7 is modulated by the FM modulator 13 and then input to the recording amplifier 12. Therefore, the laser diode 19 of the recording/reproducing head 16 generates a current and emits light according to the recording signal S9, and recording is performed on the magneto-optical disk 17.

Next, a specific example will be given and explained in detail. spindle 18
is controlled by the spindle servo circuit 20 at 1800 revolutions per minute, and the tack pulse circuit 21 outputs one pulse per revolution. The spindle servo circuit 20 controls the motor 24 so that the pulse signal S5 from the tack pulse circuit 21 and the video signal S6 are in phase. This pulse signal S9 is sent to the timing circuit 15 for 6H (
It has a delay time of 381μsec.) and 1H (63.5μsec.).
As a clock c with a pulse width of , switch 1
4 and is output to sample and hold circuits 4a and 4b. As a result, the switch 14 is switched by the clock c for a period of 1H, and outputs the reference signal S7 having a frequency of 9MHz. When the clock c is not input, the video signal S6 is output. The signal S8 output from this switch 14 is FM modulated and amplified, then drives the laser diode 19 and is recorded on the magneto-optical disk 17. On the other hand, the recorded signal is reproduced by the recording/reproducing head 16, amplified by the RF amplifier 1, and then
The signal is input to bandpass filters 2a and 2b each having a bandwidth of 30KHz and tuned to a fundamental wave (9MHz) and a second harmonic, respectively. As a result, the signals S1a and S1b, which have only single frequency components of 9MHz and 18MHz, respectively, are A/D converted through rectifier circuits 3a and 3b, sample and hold circuits 4a and 4b, and A/D converters 5a and 5b. Furthermore, digital signals S3a and S3b are generated. At this time,
The clock c output from the timing circuit 15 is used as the sampling clock. Therefore,
In CPU10, the fundamental wave component S3a and the second harmonic component
The ratio R of S3b is calculated, and the output signal S51 passes through the output port 7 and the D/A converter 11 and is amplified by the meter amplifier 22 to drive the harmonic distortion indicator 23 and display the state of harmonic distortion. becomes.

Note that FIG. 2 shows the relationship between the recording current, the fundamental wave component (C/N), and the second harmonic component (C ₂ /N) of the reproduction signal in the above embodiment.

In the above-mentioned embodiment, the case where it is applied to a magneto-optical disk system as a recording medium is shown.
Of course, the present invention is not limited to this, and can be applied to all devices that record and reproduce television signals.

[Effect of idea]

As explained above, the present invention inserts a reference signal for distortion detection into a part of the retrace period or blanking period of the television signal, extracts this reference signal and the second harmonic signal from the reproduced signal, By determining and displaying this component ratio, an appropriate recording current can be set and an image signal that is less affected by secondary distortion can be reproduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a diagram showing the relationship between the recording current, the fundamental wave component (C/N), and the second harmonic component (C ₂ /N) of the reproduction signal in the above embodiment. 1...RF amplifier, 2a, 2b...band pass filter, 3a, 3b...rectifier circuit, 4a, 4b
...Sample hold circuit, 5a, 5b...A/
D converter, 6...Input port, 7...Output port, 8...RAM, 9...ROM, 10...
CPU, 11... A/D converter, 12... Recording amplifier, 13... FM modulator, 14... Switch, 15... Timing circuit, 16... Recording/reproducing head, 17... Magneto-optical disk, 18... ...Spindle, 19...Laser diode, 21...
Tack pulse circuit, 20... spindle servo circuit, 22... meter amplifier, 23... harmonic distortion indicator, 24... motor.

Claims (1)

[Scope of utility model registration request] In a recording/reproducing apparatus for a television signal, when recording a television signal, a means for switching a part of the blanking period of the recorded television signal to a reference signal for detecting harmonic distortion and recording it on a recording medium; means for reproducing a harmonic distortion detection reference signal; means for detecting a fundamental wave component and a second harmonic component from the reproduced harmonic distortion detection reference signal; What is claimed is: 1. A recording/reproducing apparatus comprising: means for calculating a ratio with a second harmonic component and displaying the ratio, and configured to display the degree of harmonic distortion of a reproduced signal.