JPS62141888A - Carrier chrominance signal transmission method - Google Patents

Abstract

PURPOSE:To transmit a carrier chrominance signal with a broader band than a conventional method by applying frequency conversion and time base expansion to the carrier chrominance signal so as not to overlap the band with other information signal and transmitting the result while it is subjected to frequency division multiplex to the low frequency of a luminance signal to be subjected to the frequency modulation. CONSTITUTION:A color video signal incoming to an input terminal 1 is given to a Y/C separation circuit 2, the carrier chrominance signal A separated with the broader band than that of a conventional VTR is given to a frequency converter A, where the signal is subjected to the frequency conversion as, 5.689MHz in a way that the chrominance subcarrier frequency 4.43MHz is converted into, e.g., 1.259MHz. An output signal B extracted from the frequency converter 4 is given to a band pass filter (BPF) 5, from which a low frequency conversion chrominance carrier signal V having a chrominance subcarrier frequency of 1.259MHz is filtered, and the result is fed to a time axis expansion circuit 6, where the time axis is expanded into, e.g., twice. Thus, a low frequency conversion chrominance carrier signal D whose chrominance subcarrier frequency is 629kHz (=1.259MHz/2) and whose band is nearly 1/2 time of each output signal of the Y/C separation circuit 2 and the band pass filter 5 is extracted from the time base expansion circuit 6, the result is fed to an adder circuit 7, at which the signal is added to an FM luminance signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for transmitting a carrier color signal, and particularly to a color video signal recording and reproducing device such as a VTR or a video disk reproducing device, for transmitting a wideband carrier color signal. Regarding the method.

2. Description of the Related Art An example of a current color video signal recording and reproducing device is a VTR.
However, the mainstream recording and reproducing method is the low frequency conversion color recording and reproducing method.

This recording and playback method is based on the standard color video signal.
r! 1 signal and carrier chrominance signal are each divided into 111F waves, and the luminance signal is frequency-modulated using a relatively low frequency carrier wave to obtain a frequency-modulated luminance signal (FM luminance signal). Frequency conversion is performed to a low frequency region of In this method, a reproduced luminance signal and a reproduced carrier color signal are obtained by subjecting the multiplexed signal to the reverse signal processing to that used during recording, and then these two page raw signals are added to obtain a reproduced color video signal.

In FIG. 7<A), ■ indicates the frequency spectrum of the above-mentioned FM luminance signal, and ■ indicates the frequency spectrum of the above-mentioned low-pass conversion carrier color signal.

Problems to be Solved by the Invention In the VTR of the low frequency conversion color recording/playback system,
In order to widen the band of the carrier color signal for the purpose of improving the quality of color images, it is possible to widen the band of the carrier color signal with low frequency conversion, as shown by ■ in Figure 7 (B), but the tape head system The upper limit frequency that can be recorded from the performance is shown in Figure 7 (A) and (B).
, the lower sideband band of the FM luminance signal is limited as shown by IV in Fig. There was a problem in that the resolution was lowered.

For this reason, a method of recording and reproducing the luminance signal and color difference signal on separate tracks has been put into practical use, but this method requires many rotating heads, making the device complex and expensive.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a carrier color signal transmission method that solves the above-mentioned problems by transmitting a carrier color signal after low frequency conversion and time axis expansion.

Means for Solving the Problems The carrier color signal transmission method according to the present invention performs frequency conversion and time axis extension on the carrier color signal so that the band does not overlap with other information signals, and transmits the carrier color signal together with other information signals. . The carrier chrominance signal is frequency-converted and time-axis expanded, and then transmitted as a frequency-divided signal in the lower range of the frequency-modulated luminance signal. Frequency conversion and time axis compression are performed on the color signal to obtain the original time axis carrier color signal in the original band.

The active carrier color signal is both frequency converted and time expanded. Therefore, the carrier color signal is converted to a lower frequency band by the frequency conversion, and the band is compressed by time axis expansion, so that a carrier color signal with a wider band than before can be transmitted. Note that by time axis expansion, the carrier wave frequency is also converted to a lower frequency band at the same time as band compression, but as the time axis expansion ratio increases, the proportion of carrier color signal information that is thinned out increases. Therefore, as described above, by using time axis extension and frequency conversion in combination, the proportion of information that is thinned out in the carrier color signal can be reduced, and the desired broadband carrier color signal can be transmitted. can.

In addition, when transmitting a low-pass converted carrier color signal by frequency division multiplexing with a frequency-modulated luminance signal, for the low-pass converted carrier color signal separated from the transmitted frequency division multiplexed signal,
Frequency conversion and time axis compression are performed to obtain the original time axis carrier color signal in the original band, which allows broadband transmission even if a narrowband transmission line (for example, magnetic tape of a VTR) is used. It can transmit color signals and obtain high-quality color images.

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

FIG. 1 shows a block diagram of an embodiment of the present invention. In the figure, for example, a PAL system color video signal inputted to an input terminal 1 is supplied to a Y/C separation circuit 2, where it is separated into a luminance signal and a carrier color signal, respectively. The luminance signal is output by the luminance signal recording circuit 3 to the V
In the TR, the signal is subjected to well-known recording processing to become an FM luminance signal, which is then supplied to the addition circuit 7. On the other hand, conventional VTR
The carrier color signal which has been separated in a wider band than the above and has a frequency spectrum as shown in FIG.
where its color subcarrier frequency is 4.43MH
7 is for example 1.259MHZ and', t Ruyouni 5
．． The frequency is converted to 689M t-1z. The output signal of the frequency spectrum not shown in FIG. 2(B) taken out from the frequency converter 4 is passed through a bandpass filter (BPF) 5 to a color subcarrier frequency of 1.259 MH2 shown by V in FIG. 2(B).
The low-frequency 9-transformed carrier color signal is converted into a P wave to form a frequency spectrum as shown in FIG. As a result, from the time axis expansion circuit 6, the color subcarrier frequency is 629kHz (= 1.259Mt-1z/2
), a low-pass converted carrier color signal with a frequency spectrum as shown in FIG. It is supplied to the port circuit 7. The color subcarrier frequency and band of this low-pass conversion carrier color signal are approximately the same as the color subcarrier frequency and band of the conventional low-pass conversion carrier 0 signal q shown in FIG. 7(A).

Therefore, the output signal of the adder circuit 7 appears as shown in FIG. 7(A) above.
A frequency division multiplexed signal with a narrow band frequency spectrum similar to the frequency spectrum shown in FIG. recorded.

FIG. 3 shows a block diagram of an example of the time axis expansion circuit 6 mentioned above. The low frequency conversion carrier color signal input to the input terminal 12 is, for example, a COD (charge coupled φ device).
1H memories 13 and 14, which are analog memories such as
It is written at a clock frequency of 2 and read at a clock frequency of 2. Here, f+ = 2f2 is selected, and FIG. 4(B) shows IH (however, H is the horizontal scanning 11
1 interval) The low frequency conversion carrier color signal of the information schematically shown at the IS1 position is alternately written in the 1H memories 13 and 14 every 1H, and is read out in the 2H period immediately after the writing between IHif1. In addition, the switch 15 is connected to the 1H memory 13.
and 14, the readout signal of the one-day memory that is undergoing the readout operation is selectively outputted to the output terminal 16, so that the switching is performed alternately every two days. As a result, output terminal 1
6, the time axis is expanded twice as schematically shown in FIG. 4(C), and a low-pass conversion carrier color signal consisting of information for each odd numbered line is output. Note that by using three or more memories per day, the time axis can be expanded twice without missing information. Note that FIG. 4(A) schematically shows the luminance signal in units of 1H.

Here, the 1-day memory is an analog memory, but the A/D
After conversion and processing using digital memory, D
/A conversion is also possible.

Next, to explain the structure and operation of the reproduction system, FIG. 5 shows a block diagram of an embodiment of the reproduction system of the present invention. In the figure, the frequency division multiplexed signal reproduced from the magnetic tape 10 by the rotary head 9 is passed through a high-pass filter (HPF) 1.
8 converts the FM luminance signal into a P-wave, and a low-pass filter (LPF) 19 separates the low-pass conversion carrier color signal into a P-wave. The reproduced FM tone signal is supplied to a luminance signal reproduction circuit 20, where it is subjected to well-known reproduction processing in a low frequency conversion color recording and reproduction system VTR to become a reproduced luminance signal, and then supplied to an adder circuit 21. , the reproduced low frequency conversion carrier color signal as schematically shown in FIG. It will be done. The time axis compression circuit 22 consists of two 1H memories, a switch circuit that alternately supplies an input reproduction low-frequency conversion carrier color signal to their input terminals every 2H, and a 1H memory integration and readout control means. Write operations are performed on the two 1-day memories alternately every two days, and when one 1-day memory is performing a write operation, the other 1H memory performs a write operation based on a clock pulse with twice the frequency of the write operation. By repeating the read operation twice in a 2H period, when the Ryokawa power signals of the two 1H memories are added, as schematically shown in FIG.
The original time-based low-pass conversion carrier color signal is obtained in which the information is repeated twice.

The output signal of this time axis compression circuit 22 has a color subcarrier frequency of 1.259M, in which the time axis of the input reproduced low-pass conversion carrier color signal is compressed by 1z2, and the band is expanded approximately twice.
) l z low-pass conversion carrier color signal, and frequency converter 2
3, which undergoes frequency conversion and is returned to the reproduced carrier color signal in the original band of the original color subcarrier frequency 4°43M1-1z, and is then supplied to the addition n circuit 21. As a result, a reproduced color video signal is taken out from the adder circuit 21 to the output terminal 24.

In addition, according to this embodiment, as schematically shown in FIG. 4(D), the 1H color information is repeatedly reproduced and output twice, so the vertical resolution of the reproduced color information is degraded. However, since the scanning line interval is sufficiently fine compared to the horizontal resolution of the reproduced color information, the overall color image quality can be improved by widening the carrier color signal band according to this embodiment.

The time axis expansion circuit 6 shown in FIG.
．． As shown in FIG. 6, two field memories (or frame memories) 27 and 28, each supplied with a signal from the input terminal 2b, and their It may also be configured with a switch circuit 29 for switching the outputs 1 and 2, and output a time-axis expanded signal to the output terminal 30 for each field (or frame).

Further, the present invention can be applied not only to PAL system but also to NTSC system color video signals, and the input signal may be a luminance signal and a carrier color signal input separately from a television camera. It can also be applied to other recording/reproducing devices and transmission methods in general. Furthermore, the connection order of the frequency converter 4 and the time axis expansion circuit 6 and the connection order of the time axis compression circuit 22 and the frequency converter 23 may be reversed from the embodiments, or the same order as the conventional one may be used. If the carrier color signal band is sufficient, the FM luminance signal band can be enlarged by that amount, and the resolution can be improved.

Effects of the Invention As described above, according to the present invention, the carrier color signal band can be transmitted in a wider band than before, the color image quality can be improved, and the home VTR using the low frequency conversion color recording and reproducing method can be used. When applied to a recording/reproducing device with a narrow recording/reproducing band, such as the above, it has the advantage that it is possible to obtain a reproduced color video signal having a reproduced carrier color signal with a wider band than before.

[Brief explanation of drawings]

Fig. 1 is a block system diagram showing an embodiment of the recording system of the present invention, Fig. 2 is a diagram showing the frequency spectrum of signals of each part of the block system shown in Fig. 1, and Fig. 3 is an example of a time axis expansion circuit. A block system diagram showing. FIG. 4 is a diagram illustrating an example of time axis expansion and compression operations in the present invention, FIG. 5 is a block diagram showing an embodiment of the reproduction system of the invention, and FIG. 6 is a diagram illustrating an example of the time axis expansion circuit and other components. FIG. 7 is a block system diagram showing an example of the above, and FIG. 7 is a diagram showing the recording signal frequency spectrum etc. in a conventional VTR. 1... Color video signal input terminal, 2... Y/C separation circuit, 3... Luminance signal recording circuit, 4.23... Frequency converter, 6... Time axis expansion circuit, 7. 21... Addition circuit, 10... Magnetic data, 22... Time axis compression circuit, 24... Playback color video signal output terminal. Patent applicant: Victor Japan Co., Ltd. Figure 3

Claims (2)

[Claims] (1) A carrier color signal transmission method characterized in that the carrier color signal is frequency-converted and time-axis expanded so that the band does not overlap with other information signals, and then transmitted together with the other information signals. (2) A low frequency converted carrier color signal obtained by frequency converting and time axis extension of the carrier color signal is frequency-division multiplexed into the empty low frequency region of the frequency modulated luminance signal and transmitted. After separating and filtering the low-pass converted carrier color signal from the frequency division multiplexed signal, frequency conversion and time axis compression are performed to obtain a carrier color signal returned to the original time axis in the original band. A carrier color signal transmission method.