JPS63117302A - Information signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain an information signal recording and reproducing device which can decide a mode and reduce skew noises by providing a means which selects and outputs the output reproduction video signal of one specific video signal reproduction system among (n) kinds of video signal reproduction systems. CONSTITUTION:A generating means for a video signal to be frequency-modulated generates the video signal to be frequency-modulated in one optionally selected mode among (n) kinds of modes which differ in carrier frequency and outputs as a pilot signal one signal assigned previously to one optionally selected mode among (n-1) kinds of angle-modulated signals which are higher in frequency than the skew noise component of a sound and obtained by imposing angle modulation with modulating signals of mutually different (n-1) kinds of frequencies and an unmodulated carrier. This pilot signal, frequency-modulated video signal in said mode, and angle-modulated sound signal are recorded on a recording medium respectively. In reproduction, only a reproduction video signal which is extracted by a video signal reproduction system in the same mode as a recording mode is selected and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an information signal recording and reproducing device, and in particular to an information signal recording and reproducing device that records an audio signal by switching the carrier frequency of a frequency-modulated video signal according to a selected mode, and also records an audio signal on a recording medium. The present invention relates to a playback device that records and plays back the same.

Conventional technology In home VTRs, the carrier wave of the frequency-modulated luminance signal is lower than that of the current VTR standard (for example, VH8 (registered trademark)) due to the recent improvement in the performance of magnetic tape and the performance of magnetic heads. By recording and playing back with a high frequency setting, it is possible to produce high-quality images with higher resolution than images recorded and played back in the current VTR standard mode (hereinafter referred to as standard mode). High image quality [
A method for recording and reproducing data is being considered.

Problems to be Solved by the Invention However, since there is no complete compatibility between the above standard mode and the need for high image quality, it is necessary to determine in which of the above modes the video signal to be played back was recorded. , it is necessary to perform playback using the same code as when recording.

For this reason, for example, a VTR is equipped with a changeover switch for switching between a standard mode playback system and a high-quality mode playback system, and the recorded signal on the magnetic tape is first played back using either of the needs, and then the playback image is monitored while I changed the selector switch to playback in the mode that reproduced the playback image correctly.

However, this method is not only extremely inconvenient to use, but also has the problem that when playing back in a different mode, the reproduced image quality deteriorates so much that the user may mistake it for a faulty VTR.

In addition, in VTRs that record and reproduce frequency-modulated audio signals with a rotating head, the playback output of the rotating head is switched for each field, so skew noise (this is determined by noise analysis) consisting of 60H2 and its harmonics,
It has been confirmed that most of the components are below 150 Hz), which causes a problem in that the reproduced sound quality deteriorates.

The present invention was created in view of the above points, and an object of the present invention is to provide an information signal recording/reproducing device capable of mode discrimination and skew noise reduction.

Means for Solving the Problems The information signal recording and reproducing apparatus of the present invention includes means for generating a frequency modulated video signal of one mode, pilot signal generating means, and a receiver whose frequency band is different from that of the pilot signal. means for generating an angle modulated audio signal; and recording means;
It consists of a total of n types of video signal reproduction systems, audio signal demodulation circuits, pilot signal demodulation means, 1-mode discrimination signal generation means, subtraction means, and reproduction video signal selection output means.

The frequency-modulated video signal generating means generates a frequency-modulated video signal in one mode arbitrarily selected from n types of modes (where n is an integer of 2 or more) having different carrier wave frequencies. On the other hand, a signal obtained by square modulating one carrier wave with a modulation signal having a frequency higher than that of the skew noise component of the voice and having different (n-1) types of frequencies.
-1), one signal pre-assigned to one arbitrarily selected mode among the angle modulated signals of the types and one non-modulated carrier wave is generated and output as a pilot signal by the pilot signal generating means. Ru. This pilot signal, the frequency modulated video signal of the first mode, and the angle modulated audio signal are respectively supplied to a recording means and thereby recorded on a recording medium.

During reproduction, the frequency-modulated video signal in the reproduction signal reproduced from the recording medium is supplied to a total of n types of video signal reproduction systems, where each reproduction signal is subjected to reproduction signal processing specific to each of the n types of modes. On the other hand, the angle-modulated audio signal and the pylon 1 signal in the reproduced signal are each separated and then supplied to an audio signal demodulation circuit and a pilot signal demodulation means, respectively, and demodulated.

The output signal of the pilot signal demodulation means is supplied to the subtraction means, where its phase is inverted and added to the demodulated audio from the audio demodulation circuit. At the same time, the output signal of the pilot signal demodulation means is supplied to the mode discrimination signal generation means, where it is converted into a mode discrimination signal indicating the recording mode based on its level, and then supplied to the selection means, The selection means selects and outputs only the reproduced video signal taken out from the video signal reproduction system in the same mode as the recording mode from among the video signal reproduction systems of the previous type.

Embodiment FIG. 1 shows a block system diagram of an embodiment of the recording system of the present invention. In the figure, reference numeral 1 denotes a video recording system, from which an information signal including at least a frequency-modulated luminance signal (FM video signal) is passed through a recording amplifier 2 to a dedicated video head 3.
The signal is supplied to the magnetic disk 4, thereby being recorded on the magnetic disk 4.

The above-mentioned video signal is recorded in either standard need mode or high image quality mode. Here, the video signal, especially the luminance signal, is recorded on a magnetic tape in the form of a frequency-modulated luminance signal (FM luminance signal) obtained by changing the frequency of a carrier wave (FM), and is reproduced. In the standard mode, the frequency spectrum of the signal is as shown by ■ in Figure 2, and in the high-quality mode, as shown by ■ in the same figure, the carrier frequency is set higher than in the standard mode, and the carrier frequency is polarized. The range is also set widely.

During the frequency spectrum analysis of the IFM luminance signal shown in Fig. 2,
fAS, fAP, and fAW indicate carrier frequencies at the sync tip level, pedestal level, and white peak level of the luminance signal, and similarly, in the frequency spectrum, fes, f8p, and raw indicate the sync tip level, pedestal level, and white peak level of the luminance signal. Shows carrier frequency at white peak level. For example, 4! The above carrier frequency fAS in A quasi-need is 3.4MHz, and fAp is 3.4MHz.
8MH2, fAw is 4.4MHZ, and the above carrier frequency fes at high image quality needs is 5.4MH7°fBP
is 5.9M l-1'z, f a w is 7.0MH
It is z.

On the other hand, the audio signals of the 1st and 2nd channels inputted separately to the input terminals 5 and 6 are FM changed! ! are supplied to vessels 7 and 8,
Here, for example, each carrier wave of 1.3 MHz and 1.7 MHz is frequency-modulated separately and converted into two FM audio signals, and then a bandpass filter (hereinafter referred to as BPF) 9.1
After unnecessary frequency components are removed by 0, the signals are supplied to the processing circuit 11, respectively.

Further, the oscillator 12 is an oscillator that oscillates and outputs a predetermined single frequency within a sufficiently high frequency range (for example, several kHz to 20 kHz) that is five times or more higher than the R high frequency 150H2 of the skew noise component of the voice, and its output oscillation frequency is supplied as a modulation signal to the FM modulator 14 via the switch 13. Note that the output oscillation frequency of the oscillator 12 may be selected to be the horizontal scanning frequency f'H or a frequency 1/2 times that frequency.
In that case, a conventional signal generator with a horizontal scanning frequency in the recording/reproducing circuit of the VTR can be used in common as the oscillator 12.

The switch 13 is controlled so that it is turned off when the M video signal (for example, FM luminance signal) taken out from the video recording system 1 is in the standard mode, and turned on only when it is in the high quality mode.

Therefore, during recording in the standard mode, no modulation signal is supplied to the FM modulator 14, so that the FM modulator 14 outputs a single carrier wave as is.

On the other hand, when recording in high-quality mode, the FM modulator 1
4 is supplied with the output oscillation frequency signal of %tl[12 as a modulating signal through the switch 13, so the FM modulator 14 modulates the frequency of the single carrier wave with the modulating signal. The FM signal obtained is extracted.

The above-mentioned single carrier wave frequency is selected to be as close as possible to the FM audio signal, such as 2H1lz, so that the output FM signal of the FM modulator 14 does not overlap in frequency band with the FM audio signal, and is as close as possible to the FM audio signal. . As will be described later, this is because the output FM signal of the FM converter 14 is set at such a low frequency that it is recorded in the deep part of the magnetic layer of the magnetic tape 4 together with the FM audio signal, thereby affecting the recording and playback of the FM video signal. Due to the need to avoid giving. The output signal of the FM modulator 14 has a passing center frequency of 2M.
The signal is supplied as a pilot signal to the addition circuit 11 through the Hz narrowband BPFI 5.

As a result, during standard mode recording, the frequency spectrum of the output signal of the addition circuit 11 is as shown in FIG. A frequency division multiplexed signal is obtained, which is composed of the second channel FM audio signal A2 with a band of 1.7 MH7±150 kHz from 8PF10, and the pilot signal PA which is a 2MHz unmodulated carrier wave from BPF15. On the other hand, the frequency spectrum of the output signal of the adder circuit 11 during high-quality mode recording is shown in Figure 3 (
As shown in B), the FM audio signals A1 and A2 of the first and second channels and the FM from BPF15 are
This becomes a frequency division multiplexed signal consisting of the signal Pa. Therefore, the FM audio signals A1 and A2 have the same frequency spectrum regardless of whether they are in the standard mode or the high-quality mode, whereas the pilot signal is an unmodulated signal PA in the standard mode, and the FM audio signal in the high-quality mode. The signal Pa has a different frequency spectrum depending on the recording mode.

FIG. 3 (A) or (B) taken out from the adder circuit 11
A frequency division multiplexed signal having a frequency spectrum as shown in FIG.

Here, the video-dedicated head 3 and the audio-dedicated head 17 have different azimuth angles from each other, and are provided in pairs facing each other on the rotating surface of the same rotating cylinder. The head 17 scans the track on which the frequency division multiplexed signal shown in FIG. Recording is performed using a known deep recording method in which video signals, including both raw signals and raw signals, are recorded on the surface layer of the tape magnetic layer.

Next, the configuration and operation of the reproduction system will be explained with reference to FIG. In FIG. 4, the FM Terumaro signal reproduced from the surface layer of the magnetic layer of the recorded magnetic tape by the video-dedicated head 3 is supplied to the standard mode reproduction line 20 and the high-quality need reproduction system 21 through one preamplifier, respectively. , here FM
After being demodulated, it is passed through a low-pass filter having a cutoff frequency unique to that mode, and is given a differential characteristic unique to that mode.

On the other hand, the frequency division multiplexed signal having the frequency spectrum shown in FIG. 2MH2 BPF23. BPF24 with passing center frequency 1.3MH7
．． and BPF 25 with a passing center frequency of 1.7 MH2.

As a result, the frequency of the pilot signal of the frequency spectrum shown in the above PA or 2 days is extracted from the BPF 23, and after being FM demodulated by the FM demodulator 26, the low-pass filter (hereinafter referred to as [PF 1) 27 After the carrier wave component is removed by the detector circuit 28 and the LPF 3
7, respectively.

The envelope detected by the detection circuit 28! The I signal is
After integration by L P, F 29 with a cutoff frequency of about 1H2, the level is detected by level detection "1Tli 30. The level detector 30 is, for example, a comparator, and the pilot signal is the output signal of the unmodulated LPF 29. The level is compared with the output signal of the LPF 29 and a reference voltage of a predetermined level that is higher than the output signal level of the LPF 29 when the pilot signal is an FM signal, thereby generating a mode discrimination signal. do.

This mode discrimination signal is applied to the switch circuit 31 as a switching signal, and the switch circuit 31
When the luminance signal is recorded in the FA semi-mode, the reproduced luminance signal output from the standard mode reproduction system 20 is selectively outputted to the output terminal 32, while on the other hand, when the reproduced FM luminance signal is recorded in the high-quality mode, The output reproduction brightness signal of the high-quality mode reproduction system 21 is selectively outputted to the output terminal 32. In this way, the mode is determined depending on whether the reproduced pilot signal is unmodulated or modulated, and the reproduced video signal extracted from the reproduction system in the same mode as that at the time of recording is output to the output terminal 32. .

On the other hand, the reproduced FM audio signal having the frequency spectrum indicated by A+ and A2, whose frequency is selected and extracted by the BPF 24.25, is transmitted to the FM audio signal reproduction system 33.34.
After being subjected to FM demodulation, noise reduction, and other known signal processing, the subtraction circuits 35 and 36
supplied to

Further, the demodulated pilot signal taken out from the LPF 27 is band-limited by the LPF 37 with a cutoff frequency of about 200 Hz, and then supplied to subtraction circuits 35 and 36, respectively, where the demodulated pilot signal is outputted from the FM audio signal reproduction system 33 and 34 in reverse phase. added to the signal. Here, the reproduced audio signal contains a skew noise component of 150H2 or less as described above, but since the pilot signal is recorded and reproduced by the same audio q head 17 as the FM audio signal, the same Since the subtraction circuit 35 has a skew noise component of
and 36, the skew noise components in the reproduced audio signals from the FM audio signal reproduction systems 33 and 34 are completely canceled out and removed. Furthermore, this skew noise component can be removed not only when the pilot signal is unmodulated, but even when it is modulated, the modulation signal of the pilot signal is set at a frequency that is sufficiently high relative to the skew noise component. Since the modulated signal can be completely removed by the PF 37 and only the skew noise component can be extracted, the effect of removing the skew noise component can be obtained.

In this way, from the subtraction circuits 35 and 36, the output terminal 38
．． 39, the reproduced audio signal from which the skew noise component has been removed is extracted. In addition, in Figure 4, LP is used as the final audio output.
Although the illustration shows that the output of F37 is subtracted, since there is a de-emphasis circuit and a noise reducer in the FM audio signal reproduction system 33, it is difficult to simply subtract the output from the reproduced audio signal in the subtraction circuits 35 and 36. A difference occurs in the phase and level of one. In that case, it is desirable to perform subtraction through a phase compensator before a de-emphasis circuit or a noise resolution user.

Note that the present invention is not limited to the above embodiments, but includes various other modifications. for example,
An FM envelope detection means is provided on the output side of the BPF 23, which detects whether or not a pilot signal is being reproduced.If it is detected that there is no reproduced pilot signal, a means for applying muting is added. Even when a finished magnetic tape is played back, mode switching and FA operation of the skew noise canceler can be prevented.

Further, the present invention is applicable not only to magnetic tapes but also to magnetic disks, and furthermore, as shown in FIG. 3(A).

It is also possible to frequency-division multiplex the frequency-division multiplexed signal shown in (B) into an FM audio signal and simultaneously record and reproduce it using the same rotating head, etc. In this case, it is also applicable to other recording media other than magnetic recording media. be able to.

Furthermore, although the embodiment has been described as having two types of modes, three or more types may be used. In this case, the types of modulation frequencies of the pilot signal may be increased in accordance with the number of modes. Further, the pilot signal modulation method may be phase modulation.

Effects of the Invention As described above, according to the present invention, since the recording mode of the reproduced video signal can be automatically determined, it is possible to completely eliminate the complicated operation of operating the mode switching switch each time reproduction is performed. This improves usability and prevents erroneous operations such as playing in a different mode, which eliminates the possibility of mistakes being made.Furthermore, the pilot signal is used not only for mode identification, but also for modulation,
Even without modulation, it can be used to remove skew noise components in the reproduced audio signal, and furthermore, only one pilot signal Kirlia is required, and there is almost no restriction on the band of other information signals that are simultaneously recorded and reproduced. It also has a number of features, such as being able to perform recording and reproduction with only the addition of an extremely simple circuit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the recording system of the apparatus of the present invention, and FIG. 2 is a diagram showing the frequency spectrum in each mode of a frequency-modulated video signal recorded and reproduced by the apparatus of the present invention. , FIG. 3(A). (B) is a diagram showing the frequency spectrum at each aid of the frequency modulated audio signal and the pilot signal recorded and reproduced by the device of the present invention, respectively, and Fig. 4 is a block diagram showing an embodiment of the reproduction system of the device of the present invention. It is a system diagram. 1...Video recording system, 3...Video dedicated head, 4...
・Magnetic tape, 5.6...Audio signal input terminal, 7.8
゜14...FM modulator, 12...oscillator, 13...
・Switch, 17...Audio-only head, 20...Standard mode playback system, 21...High-quality need playback system, 23
...Pilot signal separation bandpass filter (BPF)
, 24°25...Band filter for FM audio signal separation (
BPF), 26...FM demodulator, 28...detection circuit, 30...level detector, 31...switch circuit,
32...Playback video signal output terminal, 33.34...F
M audio signal reproduction system, 35.36... Fraud reduction circuit, 38.
39... Re-1 audio signal output terminal. Patent applicant: Victor Japan Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] Frequency modulated video signals have different carrier frequencies n
means for generating a frequency modulated video signal in one mode arbitrarily selected from among the modes (where n is an integer of 2 or more); Any one of (n-1) types of angle-modulated wave signals obtained by angle-modulating one carrier wave with modulation signals of different (n-1) types of frequencies and the one unmodulated carrier wave. a pilot signal generating means for generating a signal pre-assigned to a selected mode as a pilot signal; a means for generating an angle-modulated audio signal having a frequency band different from that of the pilot signal; recording means for recording the frequency-modulated video signal, the pilot signal, and the angle-modulated audio signal of one mode selected in a recording medium, respectively; a total of n types of video signal reproducing systems for demodulating the frequency modulated video signals and performing reproduction processing specific to each of the n types of modes to obtain reproduced video signals; and angular modulation in the reproduced signals. an audio signal demodulation circuit that separates and demodulates the audio signals to obtain demodulated audio signals; a pilot signal demodulator that separates and demodulates the pilot signals in the reproduced signal; and an output signal level of the pilot signal demodulator. means for discriminating a recording mode based on the signal and generating a mode discrimination signal; and for outputting a reproduced audio signal by adding the output signal of the pilot signal demodulating means to the demodulated audio signal from the audio signal demodulating circuit with the output signal reversed in phase. An information signal recording and reproducing device comprising: a subtracting means; and a means for selectively outputting an output reproduced video signal of a predetermined one of the n types of video signal reproducing systems based on the mode discrimination signal.