JP2506078B2 - Television signal multiplex system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a television signal multiplexing system, and particularly to a high frequency band component of a luminance signal without changing a transmission standard of the television standard system. A high-definition television signal is transmitted by being multiplexed in the band.

[Conventional technology]

As is well known, the current color television standard system defines a transmission channel frequency band of 6 MHz.

Therefore, in this band, the horizontal spatial frequency of the luminance signal is 4.2MHz or less, and for the color signal, the color subcarrier frequency is within 4.2MHz and the line scanning frequency (15.75KHz).
A method of selecting 445/2 times 3.58 MHz and modulating and multiplexing two color difference signals I and Q is adopted.

Recently, in order to make a high-definition color television without changing the standard set by the above-mentioned television standard system, the high frequency band component of 4.2 to 6 MHz of the luminance signal which has not been transmitted conventionally is changed to the spatio-temporal frequency. A high-definition color television system for multiplexing and transmitting in a gap has been proposed.

 That is, there are the following documents as conventional techniques.

1), CPA (CoIoar Phase AIternation), "Image Transmission and Its Equipment" edited by the Television Society, P.17.

2), PAF (Phase AIternation FieId) Fujio "Problems of current color television system and high-definition television system" IEICE IE76-9 3) Configuration method of television signal Fukigaku, JP-B 59-171387 4) Frequency shift Circuit Hirano, Yoshiki, Fukigi, Japanese Patent Publication No. 6-62284 By the way, in the current color television standard system, the method itself of multiplexing another signal in the space of the space-time frequency is the above-mentioned documents 1) and 2). , Was previously known as CPA or PAF.

After that, in References 3) and 4), by multiplexing the high frequency band component of the luminance signal in this gap in the same manner as CPA and PAF, the transmission line and the receiver of the current color television standard system are provided. , A method of transmitting high-definition information while maintaining compatibility has been proposed. In these documents, a high-frequency band luminance signal is multiplexed by amplitude-modulating a carrier whose phase is inverted for each field. However, in order to use the above-mentioned space-time frequency gap, the carrier liquid As a frequency, the frequency f of the color subcarrier is practically used.
_It was limited to _SC or 0.5f _SC .

Therefore, in that case, the frequency band of the modulated multiple signal components is limited to some extent. Further, in a natural image, the lower the frequency, the more the component is included, but the low-frequency component in the high-frequency luminance signal to be multiplexed is aligned in the low-frequency direction of the original low-frequency luminance signal. It is multiplexed.

For this reason, currently widely used receivers have no means for separating the high-frequency luminance signals that are sent in a multiplexed form, so that the received image has a width that flows downward from above. It appeared as a wide striped pattern and was wider than the conventional cross color, giving a visually noticeable interference.

In order to change the signal or band to be multiplexed and the direction of the frequency of the above-mentioned multiplex signal component by the conventional technique, a complicated circuit such as two-stage modulation as shown in the above-mentioned document 4 is required.

[Problems to be solved by the invention]

Therefore, an object of the present invention is to prevent a noticeable disturbance from being given to a received image of a current television receiver even if a high-frequency luminance signal is multiplexed by a simple circuit.

[Means for solving problems]

In order to achieve such an object, the present invention provides a high frequency band of a luminance signal in a frequency band used for transmission in the current television standard system, in a band in which interference with a received image of a current receiver is minimal. The component signal is multiplexed by converting its frequency direction so as to be opposite to that of the luminance signal in the low frequency band.

That is, the present invention is a filtering means for filtering a high frequency band component of a luminance signal of a color television in a color television system in which a chrominance signal is modulated by a subcarrier and multiplexed into a low frequency band and a luminance signal for transmission. A means for subsampling the high frequency band component signal of the luminance signal filtered by the filtering means with a carrier having an integral multiple of the horizontal scanning line frequency, and the phase of the subsampled carrier for each horizontal scanning line period, It is characterized by comprising means for inverting every field period and every frame period, and means for adding the signal subsampled by the subsampling means to the low frequency band luminance signal.

[Action]

Therefore, according to the present invention, the luminance signal component in the high frequency band is converted into the low frequency band of the luminance signal and multiplexed by sub-sampling at a sampling frequency having a frequency that is an integral multiple of the horizontal synchronization signal. You can

The position of the band to be converted can be arbitrarily selected, and the direction of high and low frequencies can be easily inverted from that of the low-frequency luminance signal.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

In the following, the current color television standard system 4.
A case where a luminance signal of a high frequency component of 4.2 MHz to 6.0 MHz, for example, is multiplexed in a band of 2 MHz will be described as an example.

First, the phase control of the carrier wave in the present invention will be described with reference to FIG.

In the case of the television standard system, the phase of the carrier wave nf _h (n is an integer, f _h is a horizontal synchronizing frequency) used for subsampling is inverted line by line, field by field, and frame by frame.

With such marks the sampling frequency obtained by inverting the phase and nf _h ^*, subsampling pattern by nf _h ^* is as FIG. 2 (A).

As shown in the figure, nf _h ^* has a maximum period of 4 fields, and these are called fields 1, 2, 3, and 4 in order of time. Further, spatially, there is one cycle of four lines, so nf _h ^* has a temporal frequency of 15 Hz and a vertical spatial frequency of 525/4 in the spatiotemporal frequency domain.

Further, since the nf _h ^* sub-sampling pattern flows downward with time, n f _h ^* appears only in the first quadrant and the third quadrant in the spatiotemporal frequency spectrum as shown in FIG.

In the figure, f _SC indicates a color subcarrier.

nf _h ^* subsampled signal, since with components around the nf _h ^*, can be multiplexed high frequency component signal in the gap of the spatial frequency when the color television signal by using nf _h ^*.

Now, FIG. 1 is a circuit system diagram showing the configuration of an embodiment of the transmitting side according to the present invention.

In the figure, 1 is a band-pass filter (BPF) for extracting a high frequency component of 4.2 to 6 MHz, 2 is a subtractor, 3 is a switcher for offset sampling, and 4 is a band-pass filter for extracting a signal in which the high frequency component is converted. (BPF), 5 is an adder, 6 is a phase inverting circuit, 7 is a control signal generating circuit, and 8 is a color modulator.

 Next, the operation will be described with reference to FIG.

4.2 from the luminance signal Y by the band pass filter (BPF) 1
Extract high frequency component Y _H of ~ 6MHz.

A subtracter 2 subtracts Y _H from Y to extract a low frequency component Y _L of Y.

Y _H is sub-sampled by the switching device 3 by the sampling frequency nf _h ^* whose phase is controlled as described above, and only the required band component is extracted by the BPF 4 to form a multiplexed signal Y _H ′.

On the other hand, the color signal C in which the color difference signals I and Q are modulated by the color modulator 8 in the normal color television system is
Y _H ′ and Y _L are added by the adder 5 to form a composite color signal.

nf _h ^* is the horizontal synchronizing signal HD, vertical synchronizing signal VD, Te control signals to be collected by cerebrospinal of a color subcarrier signal f _SC from the control signal generating circuit 7, inputted to the phase inversion by the phase inverting circuit 6 nf _h Thus, the phase is controlled and obtained.

Inversion for each line and inversion for each field is HD, VD
It is obvious that the control can be performed by the phase information of the odd field and the even field obtained from Also f _SC and V
Since the relationship of D makes one cycle in two frames, the inversion for each frame can be controlled by the information obtained from this.

Thus HD, VD, the phase inversion information from only f _SC is obtained, without multiplexing the new phase information signal in the composite color signal, to easily control the phase inversion in synchronization with the transmitting side at the receiving side it can. And the original sampling frequency nf _h is HD
Since it is an integer multiple of the frequency f _h , it can be easily obtained by a synchronous oscillator or the like.

FIG. 3 is an explanatory diagram of a multiple spectrum of a high frequency component signal according to the present invention.

This figure shows the multiple signal spectrum when n = 455, that is, nf _h = 2f _SC .

The 4.2-6 MHz component of Y is folded back to 1.2-3 MHz and multiplexed.

At this time, the component near 4.2 MHz, which is relatively high as the signal level, is multiplexed in the relatively high frequency region near 3 MHz, so that interference with the image by the currently popular receiver is not conspicuous.

In addition, in many receivers that are currently popular, although the modulated I signal has a component in 2.1 to 4.2 MHz, the Q signal component is included in the 3.1 to 4.1 component to simplify the circuit.
The color signal is demodulated by extracting only the MHz band.

As is apparent from FIG. 3, Y _H ′ does not interfere with the color signal for such current popular receivers.

As described above, according to the present invention, it is possible to easily realize the multiplexing method that extremely reduces the interference given to the current popular receiver by the simple circuit.

FIG. 4 is a circuit system diagram showing the configuration of an embodiment of the receiving side according to the present invention.

In the figure, 10 is a YC separation circuit, 11 is a bandpass filter (BP
F), 12 is a sub-sampling switch, 13 is a bandpass filter (BPF) that extracts a high frequency component signal, 14.15. Is a spatio-temporal filter that extracts only a desired luminance signal, 16 is an adder, and 17 is a phase inversion circuit. , 18 is a control signal generation circuit, 19 is a color demodulator, 2
0.21 is a spatiotemporal filter that extracts only color signals.

 Next, the operation will be described with reference to FIG.

The composite color signal in which the high-frequency luminance component is multiplexed is first input to the YC separation circuit 10 and separated into the luminance signal Y _L + Y _H ′ and the color subcarrier signal C. Then, the BPF 11 extracts only the band including Y _H ′.

Switch the output signal with nf _h ^* synchronized with the transmitter 12
The high-frequency luminance signal Y _H can be separated by sub-sampling with and extracting only the 4.2 to 6 MHz band by the BPF 13.

At this time, the original luminance signal Y _L or chrominance subcarrier signal C may be mixed into Y _H as a component of a high spatiotemporal frequency or a high vertical spatial frequency in the spatiotemporal frequency domain. Remove unnecessary components of Y _H by.

On the other hand, 'added to the spatio-temporal filter 15, wherein Y _H by ± 7.5 Hz pass filter' luminance signal Y _L + Y _H from the YC separation circuit 10 is halo wave, only Y _L is output.

Y _L is added to adder 16. On the other hand, Y _H taken from the above-mentioned BPF 13 is added to the other terminal of the adder 16 and Y _L
Is added to obtain Y _L + Y _H, and the luminance signal Y of the high definition television is taken out.

The spatio-temporal filter 20.21 also acts to remove unwanted components from the color difference signals I and Q.

The spatiotemporal filters 14.20 and 21 shown by the dotted line in the figure are used if necessary depending on the degree of interference due to the multiplexing of the high frequency signal components.

The phase inversion circuit 17 and the control signal generation circuit 18 in FIG. 4 generate the horizontal synchronization signal HD, the vertical synchronization signal VD, and the color subcarrier signal f _SC as the control signals as described in FIG. 1 above. The control signal is generated by inputting to the circuit 18.

The control signal controls the phase inverting circuit 17 inverts the phase of nf _h making the sampling frequency nf _h ^* for the sub-sampling. Further, the color subcarrier signal C from the YC separation circuit 10 is demodulated by the color demodulator 19 and the color difference signals I and Q are taken out.

FIG. 5 is an explanatory view of another embodiment of the multiple spectrum of the high frequency component signal.

That is, in the figure, n = 530 and nf _h ≒ 8.4M
This is the spectrum of the multiplexed signal when set to Hz.

In this case, the luminance signal up to about 8.4 MHz can be transmitted by multiplexing over the entire 4.2 MHz band in the television standard system.

In addition to the above, the present invention can arbitrarily realize the band and frequency direction of the multiplex signal Y _H ′ by appropriately selecting n with circuits having the same configuration.

〔The invention's effect〕

As is apparent from the above, according to the present invention, since the high-frequency luminance signal can be sub-sampled and multiplexed at the sampling frequency having an arbitrary integral multiple frequency of the horizontal synchronizing signal, the signal to be multiplexed with the low-frequency luminance signal. The band and frequency direction can be freely selected.

Therefore, it is possible to easily realize a high-definition television system in which the interference given to a received image of a currently popular receiver is extremely reduced without changing the transmission standard by the current television standard system.

Furthermore, the present invention is applied to a color television standard system in Japan, and also to a color television system such as the NTSC system in the United States and the PAL system performed in Europe to obtain high quality images. High-definition television can be implemented.

[Brief description of drawings]

FIG. 1 is a circuit system diagram showing a configuration of an embodiment of a transmitting side according to the present invention, FIG. 2 is an explanatory diagram of phase control of a carrier according to the present invention, and FIG. 3 is a multiple spectrum of a high frequency component signal according to the present invention. FIG. 4 is a schematic circuit diagram showing the configuration of an embodiment of the receiving side according to the present invention, and FIG. 5 is an illustration of another embodiment of the multiple spectrum of the high frequency component signal. 1.4.11.13 ... band pass filter, 2 ... subtractor, 3.12 ... switcher, 5.16 ... adder, 6.17 ... phase inversion circuit, 7.18 ... control signal generation circuit, 8 ... color modulator, 10 ... YC separation circuit, 19 ... Color demodulator, 14.15 ... Luminance signal space-time filter, 20.21 ... Color signal space-time filter,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Yamakita 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside the broadcasting technology research institute of the Japan Broadcasting Corporation (72) Sator Yamada 1-1-10 Kinuta, Setagaya-ku, Tokyo (56) Reference JP 60-170394 (JP, A) JP 59-171387 (JP, A) JP 60-62284 (JP, A) JP 60- 176381 (JP, A)

Claims (1)

(57) [Claims] 1. A filtering means for filtering a high frequency band component of a luminance signal of a color television in a color television system in which a chrominance signal is modulated by a subcarrier and multiplexed into a low frequency band and a luminance signal for transmission. Means for subsampling the high frequency band component signal of the luminance signal filtered by the filtering means with a carrier having an integral multiple of the horizontal scanning line frequency, and the phase of the subsampled carrier for each horizontal scanning line period. And a means for inverting every field period and every frame period, and means for adding the signal subsampled by the subsampling means to the low frequency band luminance signal. Multiplex method.