JPS63240280A - Television signal synthesizer - Google Patents

Abstract

PURPOSE:To reproduce a multiplex signal excellently by providing a means for applying carrier wave elimination to a signal being brought into a residual side band by a Nyquist filter having amplitude characteristics symmetrical in odd number with respect to a video carrier frequency during a blanking period and superimposing the result on a television signal. CONSTITUTION:High-frequency components 4.2-5.2MHz of a luminance signal are subjected to frequency conversion by subcarriers of 4.2MHz so as to have a frequency of 0-1.0MHz. In this case, the phase of the subcarrier is controlled so as to be inverted by a phase controller 15 for each horizontal scanning period, for one field or for one frame. The signal subjected to frequency conversion by the subcarrier of the phase as above is given to a modulator 11. The carrier P1 obtained from an oscillator 9 is modulated in terms of amplitude by an amplitude modulator 7 by using an output signal of an adder 6. The obtained amplitude modulation wave is subjected to band limit by a 1st filter 8 to form a residual-side band and the result is fed to an adder 13. The carrier P1 shifted in terms of phase by 90 deg. by the phase shifter 10 is used as the carrier P2. The carrier P2 is subjected to double-side band amplitude modulation by using the output signal of the frequency converter 5 at the modulator 11 and the result is subjected to carrier wave elimination double-side band amplitude modulation during the blanking period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a television signal synthesis device that multiplexes and transmits another signal onto a current television broadcast signal.

Conventional technology Japan's current NTSC [National Television
System Komisotei (National Te1e)
-vision System Comm1ttee
) ] More than 25 years have passed since color television broadcasting began in 1960. In the meantime, various new television systems have been proposed in response to demands for high-definition screens and improvements in the performance of television receivers. Furthermore, the content of the programs provided is changing from simple studio programs and relay programs to programs with higher quality and more realistic images, such as cinema-sized movie broadcasts.

Current broadcasting has specifications such as 525 scanning lines, 2:1 interlaced scanning, a horizontal luminance signal bandwidth of 4.2 MHz, and an aspect ratio of 4:3 (e.g., Document Broadcasting Technology Multibook, Color Television, Japan Broadcasting Corporation, Japan). (Reference: Broadcast Publishing Association, 1961) However, against this background, a method of configuring television signals has been proposed that is compatible with current broadcasting and improves horizontal resolution. - Examples are given below. (For example, Japanese Patent Application No. 61-180333) FIG. 4 is a block diagram showing a television signal synthesis device on the transmitting side. It is assumed that the high-frequency components of the luminance signal are multiplexed and transmitted. 51 is a carrier color signal input terminal, 52 is a luminance signal input terminal, 53 is a first filter, 54 is a second filter, 55 is a frequency converter, 56 is an adder, 57 is an amplitude modulator, 58 is a third filter, 59 is an oscillator, 60 is a phase shifter, 61 is a modulator, 62 is a fourth filter, 63 is an adder,
64 is a composite television signal output terminal. The luminance signal input from the input terminal 52 is input to the first filter 53 and the second filter 54. The high frequency component of the luminance signal band-limited by the second filter 54 is transferred to a frequency converter 55.
The frequency is converted to a lower frequency range. The output of the first filter 53 is added to the carrier color signal input to the input terminal 51 by an adder 56.

The carrier wave P1 obtained from the oscillator 59 is amplitude-modulated by the amplitude modulator 57 using the video baseband signal output from the adder 56. The obtained signal is band-limited by a third filter 58 to form a residual sideband, and then added to an adder 63. The carrier wave P1 obtained from the oscillator 59 is shifted to 90 by the phase shifter 60.
The phase-shifted wave is defined as carrier wave P2. The carrier wave P2 is subjected to carrier removal double-sided band amplitude modulation using the frequency-converted signal by the frequency converter 55. The modulated signal is band-limited by a fourth filter 62 and then added to an adder 63. The output of adder 63 becomes a composite television signal. That is, the high frequency component of the luminance signal is superimposed on the video baseband signal to form a composite television signal.

FIG. 5 is a block diagram showing a television signal demodulator on the receiving side. 71 is an antenna, 72 is a tuner,
73 is a video intermediate frequency filter, 74 is a video detector, 75
76 is a carrier wave regeneration circuit, 76 is a luminance/color signal separation circuit, and 77 is a carrier wave regeneration circuit.
is a filter, 78 is a phase shifter, 79 is a multiple signal detector, 8
0 is a frequency converter, 81 is an adder, 82 is a carrier color signal output terminal, and 83 is a luminance signal output terminal. A signal sent from the transmitting side is received by the antenna 71 and sent to the tuner 72.
The signal is frequency-converted to an intermediate frequency band by the video intermediate frequency filter 73, and is band-limited by the video intermediate frequency filter 73. The band-limited signal is supplied to a video detector 74 and a carrier wave recovery circuit 75. In the carrier wave regeneration circuit 75, carrier waves 1. Play. The band-limited signal is transmitted to a video detector 74 using a carrier wave.
The signal is detected and becomes a video baseband signal. The video baseband signal is separated into a luminance signal and a carrier color signal by a luminance/color signal separation circuit 74, and the separated carrier color signal is outputted to an output terminal 82. Further, the output of the tuner 72 is band-limited by a filter 77. The output signal of the filter 77 is transferred to the multiple signal detector 79 using the carrier wave I2 obtained by shifting the carrier wave 1 obtained from the carrier wave regeneration circuit 75 by 90° in the same direction as the phase shifter 78 in the same direction as the direction in which the phase was shifted on the transmitter side. Synchronous detection is performed at The detected signal is converted to its original frequency by a frequency converter 80, and is added to the low frequency component of the luminance signal separated by the luminance/color signal separation circuit 76 in an adder 81 to form a wideband luminance signal and sent to the output terminal. 8
3 is output.

Problems to be Solved by the Invention As mentioned above, when a carrier wave is orthogonally modulated using a multiplexed signal and a band-limited signal is superimposed on a modulated main video signal, transmission distortion such as ghosting may occur depending on the video detection method. When the main video signal is being used, crosstalk between the multiplexed signal and the main video signal is likely to occur and cause interference. Furthermore, when transmission distortion such as ghosting occurs, crosstalk between the main video signal and the multiplexed signal also occurs, making it difficult to reproduce the multiplexed signal well.

The present invention has been made in view of these problems, and is compatible with current television systems, and is particularly characterized by reducing interference to current television receivers and reducing the effects of transmission distortion. It is an object of the present invention to provide a television signal synthesis device that can multiplex transmit a large amount of information within a band defined by a standard.

Means for Solving the Problems In order to solve the above-mentioned problems, the television signal synthesis device of the present invention provides a television signal synthesis device that combines the vestigial sideband amplitude within the vestigial sideband of a vestigial sideband amplitude modulated television signal or the vestigial sideband amplitude. Multiplexing is performed by subcarriers whose phase is inverted every horizontal scanning period, every field, or every frame, in a band symmetrical to the vestigial sideband or in both bands with respect to the frequency of the video carrier wave of modulation. A multiplexed signal obtained by converting the frequency of a signal, in which a carrier wave having the same frequency as the video carrier wave and having a phase different by 90 degrees is modulated in double-sided band amplitude, the amplitude is attenuated by half at the video carrier frequency, and the amplitude is oddly symmetrical with respect to the video carrier frequency. The present invention is configured to include means for removing a carrier wave from a signal made into a vestigial sideband by a Nyquist filter having characteristics during a retrace period and superimposing it on the television signal.

Effect of the Invention The present invention uses the above-described method to generate a television signal that enables multiplex transmission of different information within the band of the current television broadcasting standard, so that a dedicated receiver can transmit images of conventional television broadcasting. Not only that, but also multiplexed information can be obtained, and furthermore, even current television receivers can receive television broadcast images with almost no problems. It is also possible to reduce the influence of transmission distortion.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a television signal combining apparatus on the transmitting side in one embodiment of the present invention. An example of multiplexing high-frequency components of a luminance signal will be explained.
The multiplexed signal is not limited to the high frequency component of the luminance signal. 2
is a luminance signal input terminal, 3 is a frequency separator, 5 is a frequency converter, 4 is a subcarrier, 15 is a phase controller, 1 is a carrier color signal input terminal, 6 is an adder, 7 is an amplitude modulator, 8 is a 1st filter, 9 an oscillator, 10 a phase shifter, 11 a modulator, 1
2 is a second filter, 13 is an adder, and 14 is a composite television signal output terminal. A frequency separator 3 separates the brightness signal into a high-band brightness signal component Y and a low-band brightness signal component YL. The low-band luminance signal component YL is added to the carrier color signal by an adder 6. The high-frequency luminance signal component Y is frequency-converted by a frequency converter 5 using a subcarrier. Figure 3 (al (b)
As shown in, for example, the high frequency components 4.2 to 5. of the luminance signal.
2MHz to 1.0MHz with 4.2MHz subcarrier
The frequency shall be converted to At this time, the phase of the subcarrier is controlled by the phase controller 15 so that the phase thereof is inverted every horizontal scanning period, every field, or every frame. A signal frequency-converted by the subcarrier having such a phase is input to the modulator 11. A carrier wave P obtained from an oscillator 9 is amplitude-modulated by an amplitude modulator 7 using the output signal of the adder 6 . The obtained amplitude modulated wave is
Adder 1 after band limiting with filter 8 to create residual sideband
Add to 3. The carrier wave P1 obtained from the oscillator 9 is shifted in phase by 90 degrees by the phase shifter 10, and the carrier wave P2 is obtained. In the modulator 11, the carrier wave P2 is amplitude-modulated in both sidebands using the output signal of the frequency converter 5, and during the retrace period, the carrier wave is removed and amplitude-modulated in both sidebands. Note that the phase shift direction of the phase shifter 10 may be fixed, but it may also be changed, for example, every horizontal scanning period. The modulated signal is band-limited by the second filter 12 and then added to the adder 13.

The output of adder 13 becomes a composite television signal.

That is, the multiplexed signal is superimposed on the video baseband signal to form a composite television signal. Although the output signal of the first filter and the output signal of the second filter are added here, the output signal of the second filter is added to the output signal of the amplitude modulator 7 and then inputted to the first filter 8. The output signal of one filter 8 may be a composite television signal.

Next, a television signal demodulation device on the receiving side in an embodiment of the present invention will be described. In the following, we will take the case of terrestrial broadcasting as an example, and assume that high-frequency components of luminance signals are multiplexed and transmitted. FIG. 2 is an example of a block diagram of a television signal demodulator. 31 is an antenna, 32 is a tuner, 33 is a video intermediate frequency filter, 34 is a video detector,
35 is a carrier wave regeneration circuit, 37 is a filter, 38 is a phase shifter, 39 is a multiple signal detector, 36 is a luminance/color signal separation circuit, 41 is an adder, 40 is a frequency conversion circuit, 42 is a carrier color signal output terminal , 43 is a luminance signal output terminal, and 44 is a subcarrier input terminal. A signal sent from the transmitting side is received by an antenna 31, frequency-converted to an intermediate frequency band by a tuner 32, and band-limited by a video intermediate frequency filter 33. The band-limited signal is supplied to a video detector 34 and a carrier recovery circuit 35. The carrier wave regeneration circuit 35 regenerates the carrier wave I for synchronous detection. The band-limited signal is detected by the video detector 34 using the carrier wave 11.

Further, the output of the tuner 32 is band-limited by a filter 37. The carrier wave 1 obtained from the carrier regeneration circuit 35 is phase-shifted by 90° in the same direction as the transmitting side by the phase shifter 38, and the band-limited signal is transmitted to the multiplex signal detector 3.
9, synchronous detection is performed. The detection output is from frequency conversion circuit 4
0, the frequency is converted using a subcarrier with the same frequency and phase as the subcarrier during transmission, and the high-band luminance signal component Y)I
becomes. The output of the video detector 34 is input to a luminance/chrominance signal separation port 36, where it is divided into a carrier color signal C and a low-band luminance signal component YL.
separated into The high-band luminance signal component YH and the low-band luminance signal component YL are added by an adder 41 to form a wide-band luminance signal.

As mentioned above, by inverting the phase of the subcarrier that frequency-converts the multiplexed signal every horizontal scanning period, every field, or every frame, crosstalk of the multiplexed signal with respect to the main video signal can be avoided. Even if this occurs, the phase of the crosstalk component is inverted every horizontal scanning period, every field, or every frame, so it is not visually noticeable. That is, less interference is caused to current television receivers. In other words, in the same way as in the NTSC system, the phase of the color subcarrier is selected to be inverted every horizontal scanning period and every frame, so that interference during multiplexing of color signals can be reduced by the accumulation effect of the eye. The following can be said.

Also, if there is transmission distortion such as ghosting during multiplex signal demodulation,
Crosstalk between the main video signal and the multiplexed signal may occur. However, the phase of the subcarrier that converts the frequency of the multiplexed signal is inverted every horizontal scanning period, every field, or every frame, and when demodulating the multiplexed signal, the subcarrier with the same phase as this subcarrier is used to convert the frequency. By converting, the multiplexed signal can be reproduced with normal phase. Since crosstalk between the main video signal and the multiplexed signal due to transmission distortion has an inverted phase, even if crosstalk occurs, it is not visually noticeable. That is, the influence of transmission distortion can be reduced even during multiplex signal demodulation.

In addition, the phase of the subcarrier that frequency-converts the multiplexed signal is inverted every horizontal scanning period and every frame,
And if the phase is controlled so that they are in phase after 263 horizontal scanning periods, then when the color subcarriers are in phase after -field, the phase of the subcarrier that frequency-converts the multiplexed signal will be in reverse phase, which is applied to the color. The interference is further reduced by the accumulation effect of the eyes.

Effects of the Invention As is clear from the above explanation, it is possible to visually reduce the effects of crosstalk between the main video signal and multiplexed signals, thereby reducing interference to current television receivers and reducing the number of multiplexed signals. I was able to complete eight laps in good condition.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a television signal combining device on the transmitting side according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a television signal demodulating device on the receiving side according to an embodiment of the present invention. Fig. 3 is a frequency conversion diagram of the high-frequency component of a luminance signal, Fig. 4 is a block diagram showing a television signal synthesis device on the transmitting side in the conventional example, and Fig. 5 is a television signal demodulation on the receiving side in the conventional example. FIG. 2 is a block diagram showing the device. 5... Frequency converter, 10.38...
Phase shifter, 12...Second filter, 15...
. . . Phase controller, 33 . . . Video intermediate frequency filter, 37 . . . Filter.

Claims (2)

[Claims] (1) Within the vestigial sideband of a vestigial sideband amplitude modulated television signal, or within a band symmetrical to the vestigial sideband with respect to the frequency of the video carrier wave of the vestigial sideband amplitude modulation, or within both bands. , a multiplexed signal obtained by converting the frequency of a multiplexed signal using a subcarrier whose phase is inverted every horizontal scanning period, every field, or every frame, and a carrier wave having the same frequency as the video carrier wave and having a phase different by 90 degrees. The signal is amplitude modulated in both sidebands, attenuated by half at the video carrier frequency, and made into a vestigial sideband by a Nyquist filter having amplitude characteristics oddly symmetrical with respect to the video carrier frequency, and the carrier is removed during the retrace period. A television signal synthesis device characterized in that it is superimposed on a television signal. (2) The subcarrier is a signal whose phase is inverted every horizontal scanning period and every frame, and whose phase is controlled so that it becomes the same phase after 263 horizontal scanning periods ( 1) The television signal synthesis device according to item 1).