JPS6382189A - High definition television signal transmission equipment - Google Patents

Abstract

PURPOSE:To make disturbance due to high definition information inconspicuous at the time of reception by an existing NTSC system receiver by modulating and multiplexing high definition information of high frequency components in the same phase as that of the Q axis of a chrominance carrier. CONSTITUTION:A transmission signal NTSC is inputted to a time spatial filter 8 at the reception side and a high definition luminance signal YH' is extracted. Then a subtraction circuit 14 subtracts a high definition luminance signal YH from a transmission signal NTSC' to form NTSC signal and a color decoder 9 separates it to a luminance signal Y and color difference signals I, Q. On the other hand, a carrier wave having a frequency fsc and a phase in phase with the Q axis obtained from a phase shifter 22 is inverted at each field by a phase inverter 13 and a switch S and the result is fed to a 1st demodulator 23. The output of the time spatial filter 8 is subjected to synchronizing detection by the 1st demodulator 23 and becomes a signal YH''. Furthermore, the output of the 1st demodulator 23 is subjected to synchronizing detection by a 2nd demodulator 25, becomes a high definition luminance signal YH by a high-pass filter 26 and synthesized with the luminance signal Y by the adder 15.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a television signal transmission device, and in particular, in a television high-definition signal multiplexing system that has full compatibility with the current NTSC system, it is applicable to current receivers. This is to reduce interference.

[Conventional technology]

Several high-definition television signal multiplexing systems that are fully compatible with current television signals have been proposed.

Figure 3 shows, for example, the Institute of Electronics and Communication Engineers, Technical Research Report C383-
61.rProposal of high-definition TV system with complete communication performance
This is an example of a conventional high-definition information insertion circuit based on the high-definition information multiplexing method described in (July 29, 1981),
Similarly, FIG. 4 shows a high-definition information reproducing circuit.

In FIG. 3, (Y+YH) is a luminance signal, I.

Q is the color difference signal, fsc is the color subcarrier, and the luminance signal (
YYH) and color difference signals I and Q are input to a color encoder 1 and converted into NTSC signals. At this time, even if the luminance signal (Y+YH) is input, the band is limited to 4.2 MHz. Also, the luminance signal (Y+YH) is filtered through the high-pass filter 2.
The high-definition luminance signal YH is separated manually and sent to the modulator 3.
is input. In this modulator 3, a color subcarrier fsc is set to fsc/2 by a frequency divider 5, which is inverted for each field by a phase shifter 6, and this is used as a carrier wave. The output of the modulator 3 is input to a bandpass filter 4, and a frequency-shifted high-definition luminance signal YH' is extracted. This YH' and the output of the color encoder 1 are combined by an adder 7 to obtain a transmission signal NTSC'.

As shown in Figure 4, the receiving side receives the transmitted NTSC
'The signal is input to the spatio-temporal filter 8 and a frequency-shifted high-definition luminance signal YH' is extracted. This Y again
H' is input to a demodulator 10, and its output is input to a high-pass filter 11, thereby regenerating a high wiIII luminance signal YH. On the other hand, the output of the spatio-temporal filter 8 is subtracted from the transmission signal NTSC' by a subtracter 14 to obtain an NTSC signal.

This NTSC signal is separated into a luminance signal Y and color difference signals I and Q by a color decoder 9, and the high-definition luminance signal YH is added to the luminance signal Y by an adder 15 to reproduce a reproduced luminance signal (Y+YH). .

Next, the operation will be explained. In FIG. 5, the horizontal axis shows the temporal frequency f, and the vertical axis shows the spatial frequency ν in the vertical direction. C in the figure is a color signal component, and in the current NTSC system, the first and third quadrants are vacant, and the high-definition luminance signal YH is frequency-shifted and inserted into these quadrants. FIG. 6 shows this frequency shift, and by amplitude modulating the high-frequency component (4 to 6 MHz) of the luminance signal with a carrier wave of 2 of the color subcarrier frequency fsc (2.2 to 4.2 MHz). perform a frequency shift. If the signal of YH is EH(t), then EH' (t)-E)l(t)・cos2πfC-t
...(1) For simplicity, let EH(t) be a sine wave with frequency fH, then EH' (t) = cos(2πfH-t +ψ) ・
cos2πfc −t=”A [cos (2π(
fc +fH)t+ψ)+cos (2yr(fc
-fH)t+ψ)]...(2) It can be expressed as follows. From this, by taking the lower sideband, it is possible to shift the frequency to the lower range. By the way, FIG. 7 shows the phase of the subcarrier in each field of the television signal, and it shows the phase of the subcarrier in each field of the television signal.
c=3.58 MHz) when connecting scanning lines with the same phase,
It is set to go up field by field. On the other hand, in order to multiplex signals at the high-definition information insertion position (position YH'') shown in FIG. 5, the subcarrier μ is lowered for each field.

need to be set. This can be proven by performing three-dimensional Fourier transform on equation (1), but this is omitted here.

In FIG. 3, the carrier wave input terminal of the modulator 3 receives a high-definition information subcarrier μ which is obtained by dividing the frequency of the color subcarrier fsc by two and inverting it for each field. is input, and YH is frequency shifted.

The input NTSC' signal in FIG. 4 is processed by a space-time filter 8 to extract the YH'' portion shown in FIG. Detailed information subcarrier μ.Y by
H'' is synchronously detected to obtain a high-definition luminance signal YH.

[Problem that the invention seeks to solve]

Since the conventional system is configured as described above, current color receivers receive the inserted YH' signal as color information. Therefore, images containing high-definition components with high levels will cause interference.

This invention was made in order to solve the above-mentioned problems. In current receivers, high-definition signals are reproduced as magenta-yellow-green colors with low visual sensitivity, making it possible to transmit television signals without noticeable interference. The purpose is to obtain equipment.

[Means for Solving the Problems] A television signal transmission device according to the present invention includes means for dividing a broadband television signal into a low frequency component and a high frequency component, In a device that performs frequency multiplex transmission by frequency shifting, the high frequency component is modulated and multiplexed using a carrier wave that is in phase with the Q axis of the color subcarrier.

[Effect]

In this invention, a wideband television signal is divided into a low frequency component and a high frequency component, and high definition information, which is the high frequency component, is modulated in phase with the Q axis of a color carrier wave to shift the frequency. Since the high-definition information is received by a current NTSC receiver, it is reproduced as a magenta-backline color with low visual sensitivity, and interference caused by the high-definition information becomes less noticeable.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a transmitting side of a television signal transmission apparatus according to an embodiment of the present invention, that is, a high-definition television signal insertion circuit. In the figure, 1 is a color encoder, 2 is a high-pass filter, and 16 is a color subcarrier. As input, 1.12fsc
(4,0MHz), 17 is a first modulator connected to the high-pass filter 2, 18 is a low-pass filter connected to the output of the first modulator 17, 19 is a color subcarrier 6 is a phase inverter connected to the output of the phase shifter 19, 20 is a second modulator connected to the output of the low-pass filter 18, and 21 is a second modulator 20. A bandpass filter connected to the output of 7 is a color encoder 1.
and an adder connected to the output of the bandpass filter 21.

FIG. 2 shows the receiving side, that is, the high-definition television signal reproducing circuit. 22 is a phase shifter that receives the color subcarrier as an input; 13 is a phase inverter connected to the output of the phase shifter 22; 23 is the output of the spatiotemporal filter 8 and the phase inverter 13; A first demodulator 24 connected to the input and output of the
．． 12 a synchronous oscillator that generates fsc; 25 a second demodulator connected to the outputs of the first demodulator 23 and the synchronous oscillator 24; 26 a high-pass filter connected to the output of the second demodulator 25; is an adder connected to the outputs of the high-pass filter 2G and the color decoder 9.

Next, the operation will be explained. FIG. 8 shows the phase of the carrier color signal in the NTSC system. The Q-axis and ■-axis are shifted by +33° from the BY-axis (0°) and the RY-axis (90°), respectively, in consideration of visual sensitivity to color.

FIG. 9 shows the visual chromaticity spatial frequency characteristics, and there is a relative sensitivity difference of about -15 dB at 2 MHz (at a viewing distance of 4 h) on the Q axis with respect to the ■ axis. Utilizing this, in the current system, the ■-axis is transmitted in a wide band, and the Q-axis is transmitted in a narrow band, in order to efficiently utilize the band.

By the way, when YH is inserted into the spatial frequency shown in FIG. 5, in the current receiver, YH is also demodulated as color signal C, causing interference. Therefore, by modulating and inserting this YH on the above-mentioned Q axis, the interference can be made less noticeable. The method of inserting this YH will be described below.

FIG. 10 shows high-definition luminance signals YH (4 to 5.
38 MHz) is a one-dimensional frequency spectrum diagram showing an example of the insertion method. , this is modulated with a carrier wave having the same phase as the Q axis of the color subcarrier fsc as shown by 1 m (cl) and inserted as YH'.

In FIG. 1, a luminance signal (Y+YH) is input to a high-pass filter 2 to extract a high-pass luminance signal YH. Also, the luminance signal (Y+YH) and color difference signal I are sent to the color encoder 1.
, Q are input and converted to NTSC signals. At this time, even if the luminance signal (Y+YH) is input, the band is 4.2
Limited to MHz. Furthermore, the synchronous oscillator 16 to which the color subcarrier fsc is input has a frequency of 1.12fsc (4.0M
IX) is supplied to a first modulator 17, the output YH of the high-pass filter 2 is modulated by this first modulator 17, and YH having a band of 4 to 5.38 MHz is modulated to 0 to 1. .3
It has a band of 8 MHz and performs frequency shift to YH''.

The output of the first modulator 7 is filtered to remove the upper sideband and carrier wave and is input to the second modulator 20. On the other hand, in the phase shifter 19, when the phase of the color subcarrier fsC is the same as the color burst phase, -14
A carrier wave with a Q-axis phase is created by shifting the signal by 7 degrees, and the carrier wave inverted for each field by the phase inverter 6 and the switch S is supplied to the second modulator 20. The inversion for each field is as shown in the conventional example. From the high-frequency luminance signal modulated by the second modulator 20, a band of 2.2 to 4.2 MHz including both side bands shown in FIG.
This YH' is combined with the output of the color encoder 1 by the adder 7 and becomes the transmission signal NTSC'.
becomes.

Furthermore, on the receiving side in FIG.
is extracted. Then, by the subtraction circuit 14, the transmission signal N
NTS by subtracting the high-definition luminance signal YH from TSC'
A C signal is separated into a luminance signal Y and color difference signals I and Q by a color decoder 9. On the other hand, the carrier wave obtained by the J phase shifter 22 and having the frequency fsc and the same phase as the Q axis is inverted for each field by the phase inverter 13 and the switch S, and is supplied to the first demodulator 23. . The output of the spatio-temporal filter 8 is synchronously detected by the first demodulator 23 and becomes YH'''.
takes the color carrier as input and outputs 1.12 fsc, and this output is input to the second demodulator 25. The output of the first demodulator 23 is synchronously detected by the second demodulator 25, and the original band (4 to 5.3
8 MHz) is extracted and becomes a high-definition luminance signal YH,
The adder 15 combines the luminance signal Y separated by the color decoder 9 to produce a reproduced luminance signal (Y + Y
H).

In this embodiment, high-definition information is transmitted using the Q of the color subcarrier.
Since it is modulated and multiplexed in the same phase as the axis, when received by a current NTSC receiver, this high-definition information is reproduced as a magenta-yellow-green color with low visual sensitivity, so that interference is not noticeable.

In the above embodiment, multiplexing of high-frequency luminance signals has been described, but the high-definition information to be multiplexed is not limited to this, and it is of course possible to multiplex high-frequency color signals, for example.

In that case, it is possible to transmit a high-definition television signal that has a wide color signal band and is compatible with the current NTSC system.

Furthermore, although not particularly limited in the above description, each of the circuits described above is generally configured with a digital circuit in the current technology.

Furthermore, in the above embodiment, the color subcarrier having the same phase as the Q axis is the same as that used in the color encoder and color decoder, and there is no need to provide a separate phase shifter.
A similar effect can be obtained even if the signal is supplied from a color encoder and a decoder.

〔Effect of the invention〕

As described above, according to the present invention, a high-definition television signal is obtained by dividing a wideband television signal into a low frequency component and a high frequency component, and frequency-shifting the high frequency component to perform frequency multiplex transmission. In the transmission device, the high-definition information, which is the high frequency component, is modulated and multiplexed in the same phase as the Q-axis of the color carrier wave, so when received by the current NTSC receiver, this high-definition information is visually visible. It is reproduced as a magenta-yellow-green color with low sensitivity, and the high-definition information has the effect that stone interference is less noticeable.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a high-definition television signal insertion circuit according to an embodiment of the present invention, FIG. 2 is a diagram showing a high-definition television signal reproducing circuit according to an embodiment of the present invention, and FIG. 3 is a diagram showing a conventional high-definition television signal reproducing circuit. FIG. 4 is a diagram showing a high-definition television signal insertion circuit; FIG. 4 is a diagram showing a conventional high-definition television signal reproducing circuit; FIG. Figure 6 is a one-dimensional spectrum diagram based on the conventional high-definition information multiplexing system, Figure 7 is an explanatory diagram of the phase of carrier waves for each field of a television signal, and Figure 8 is an N spectrum diagram.
A diagram showing the phase of the TSC system carrier color signal, FIG. 9 is a diagram showing the visual sensitivity characteristics of the ■-axis system and the Q-axis system, and FIG. 10 is a one-dimensional spectrum showing the high-definition multiplexing system according to an embodiment of the present invention. It is a diagram. 1... Color encoder, 2, 11. '26... High-pass filter, 3... Modulator, 4, 21... Bandpass filter, 5.12... Frequency divider, 6, 13... Phase inverter, 7°15...・Adder, 8... spatiotemporal filter,
9... Color decoder, 10... Demodulator, 14...
・Subtractor, 16°24 synchronous oscillator, 1.7.20...
1st. Second modulator, 18...low pass filter, 19.
22... Phase shifter, 23.25... 1st. Second demodulator. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A high-definition television signal transmission device that divides a wideband television signal into low-frequency components and high-frequency components, and frequency-shifts the high-frequency components, which are high-definition information, to perform frequency multiplex transmission. a carrier wave generating means for generating a carrier wave having the same phase as the Q-axis of the color subcarrier; a modulating means for modulating the high frequency component using the carrier wave; and a modulating means for modulating the high frequency component using the carrier wave; A high-definition television signal transmission device comprising: frequency multiplexing means for frequency multiplexing a television signal and outputting it as a transmission signal.