JPS63240281A - Television signal transmitter - Google Patents

Abstract

PURPOSE:To expand an aspect ratio while providing compatibility to an existing television system by superimposing a video signal at both sides of the screen to make the screen aspect ratio longer laterally within a band of a television signal subjected to residual-side band amplitude modulation and inverting alternately the positive modulation and negative modulation of the superimposed signal. CONSTITUTION:A carrier wave P1 obtained from an oscillator 24 of an orthogonal modulation circuit 4 is subjected to amplitude modulation by an amplitude modulator 22. The amplitude modulation wave is subjected to band limit by a 1st filter 23 and formed in the residual-side band and the result is fed to an adder 29. The carrier wave P1 is shifted in terms of phase by 90 deg. by a phase shifter 25 as a carrier wave P2. A multiplex signal inputted from a multiplex signal input terminal 26 is used to apply double-side band amplitude positive modulation to the carrier wave P2 by the positive modulation circuit 27 and negative modulation is applied by a negative modulation circuit 28. The modulated signal is selected alternately by each horizontal period or a field by a selection circuit 29. The selected signal is subjected to band limit by a 2nd filter 30 and fed to an adder 31. Thus, a multiplex signal is superimposed on a conventional video signal to form the synthesized television signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a television signal transmitting device that multiplexes and transmits a separate video signal to a current television broadcast signal to provide a screen that is wider than ever before. .

Conventional technology Our country's current NTSCr National Television System Committee (National Television System Committee)
More than 25 years have passed since color television broadcasting using the J format began in 1960. Meanwhile, with the demand for high-definition screens and improvements in the performance of television receivers, various new television systems have been proposed.

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 uses 525 scanning lines, 2:1 interlaced scanning,
It has a luminance signal horizontal bandwidth of 4.2 MHz, an aspect ratio of 4: colorimetry, and three specifications (for example, see Literature Broadcasting Technology Bibook, Color Television Japan Broadcasting Corporation Report, Japan Broadcasting Publishing Association, 1961).

Against this background, a method of configuring a television signal has been proposed that is compatible with current broadcasting and allows an enlargement of the aspect ratio. - Examples are given below.

For example, by attaching a special lens that reduces only the horizontal direction to the front of a television imaging camera that has sufficient resolution with a conventional aspect ratio of 4:3, it is possible to achieve an aspect ratio of, for example, 5:3.
It is possible to obtain a wide aspect video signal whose horizontal frequency is the same as that of a normal television signal (FIG. 2(a)). This signal is divided on the time axis into a central portion with an aspect ratio of 4:3 (FIG. 2(b)) and portions on both sides thereof (FIG. 2(C)).

In the central part, the time axis is expanded by about 5/4 times to make it a normal television signal, making it a normal video signal. This signal is sent as a conventional television signal.

Both side parts are also expanded by about 4 times on the time axis, and the video carrier waves are orthogonally modulated and multiplexed to be transmitted as video signals on both sides of the screen to make the screen aspect ratio horizontally long (for example,
No. 1-180336, Japanese Patent Application No. 1983-231667).

Problems to be Solved by the Invention As described above, in current television broadcasting, the signal band is limited by the standard, and it is not easy to add a large amount of information. For example, from the viewpoint of compatibility with current television broadcasting, the above-mentioned conventional example has a problem in that it causes interference with old envelope detection type televisions. In other words, there is no problem with the synchronous detection method because a new multiplexed signal is superimposed using orthogonal carrier waves, but because envelope detection cannot separate orthogonal components, crosstalk between the main signal and the multiplexed signal occurs, which appears as interference on the screen.

From the perspective of effective use of radio wave resources, it is not possible to expand the transmission band unnecessarily to solve the problem.

The present invention was made in view of these problems, and is compatible with the current television system, and does not cause significant interference to older receivers within the band specified by the standard.
It is an object of the present invention to provide a television signal transmitting device that enables expansion of the aspect ratio.

Means for Solving the Problems In order to solve the above problems, the television signal transmitting device of the present invention includes a time-domain video signal extraction circuit, a time-domain expansion circuit, and an orthogonal modulation circuit, and has a residual sideband amplitude. The orthogonal modulation circuit generates and transmits a signal in which a 16 carrier wave having the same frequency as the carrier wave and having a phase difference of ±90 degrees is modulated with a multiplexed signal different from the television signal within the band of the modulated television signal. The multiplexed signal is a video signal on both sides of the screen to make the screen aspect ratio horizontally elongated, which is created by the time-domain video signal extraction circuit and the time-domain expansion circuit, and the orthogonal modulation circuit includes a positive modulation circuit and a negative modulation circuit. It is characterized in that it includes a modulation circuit and alternately performs positive modulation and negative modulation for each horizontal scanning line or for each field.

The present invention uses the above-described transmitting device to generate a television signal that enables multiplex transmission of video signals on both sides of the screen in order to make the screen aspect ratio horizontally elongated within the band of the current television broadcasting standard. With a dedicated receiver, it is possible to obtain not only conventional television broadcast images but also multiplexed wide aspect images, and even with existing envelope detection type television receivers, crosstalk caused by multiplexed signals is noticeable. It is possible to receive conventional television broadcast images without any problems.

EMBODIMENTS Below, the real side of the television signal transmitting apparatus of the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram illustrating a television signal transmitting device on the transmitting side according to an embodiment of the present invention. 1 is a time axis video signal extraction circuit, 2 is a time axis expansion circuit 1.3
2 is a time axis expansion circuit, 4 is an orthogonal modulation circuit, and 5 is a timing control circuit.

6 is a wide aspect video signal, 7 is a normal video signal, and 8 is a wide aspect video signal.
is a video signal at both ends of the screen, 9 is a composite television signal, and 10 is a composite television signal.
are left and right position control signals.

The wide aspect video signal 6 has an aspect ratio of 5, for example.
:3 is a video signal with a screen that is wider than usual, and the horizontal frequency is the same as a normal television signal. (Figure 2 (
a)) This signal is divided by the time-domain video signal cutting circuit 1 into a central portion with an aspect ratio of 4:3 (FIG. 2(C)) and portions on both sides thereof (FIG. 2(C)). The central portion is expanded by about 5/4 times in the time axis expansion circuit 12 to become a normal television signal, and becomes a normal video signal. Both side parts are expanded by about 4 times by the time axis expansion circuit 23, and the image signals 8 at both ends of the screen are expanded.
becomes. The image signals 8 at both ends of the screen are input to the orthogonal modulation circuit 4 as multiplexed signals. The orthogonal modulation circuit 4 performs orthogonal modulation together with the normal video signal 7 and outputs a composite television signal 9. Each block will be explained below.

First, time axis video signal extraction circuit 1, time axis expansion circuit 1
2. The time axis expansion circuit 23 will be explained. These circuits can be easily realized by using a line memory and changing the write clock and read clock, so detailed configurations will be omitted.

Although the operation has been described above, FIG. 3 further shows an example of the image. FIG. 3 shows this operation by the position of the image. FIG. 3 (al is wide aspect video signal 6, (
b) is a normal video signal 7, and fc) is a screen both-ends video signal 8. In FIG. 3, the signals at both ends of the screen have the same width on the left and right sides, but it is also possible to change the width using the left and right position control signals 10. The left/right position control signal 10 can be transmitted as digital data, for example, during the vertical retrace period, if necessary.

Next, the orthogonal modulation circuit 4 shown in FIG. 1 will be explained.

FIG. 4 is a spectrum diagram showing a method of modulating a television signal modulated by the orthogonal modulation circuit 4 of FIG.

FIG. 4 (al) is a spectrum diagram of a television signal subjected to vestigial sideband amplitude modulation in the current television system. Here, a case is shown in which the lower sideband of the video carrier P1 is a vestigial sideband. Tbl in FIG. 4 is a multiplexed signal different from the television signal shown in FIG.
2, residual sideband amplitude modulation is performed so as to remove the carrier wave P2 during the retrace period. FIG. 4 (C1) is a signal obtained by multiplexing the signal of FIG. 4 To) with the television signal of FIG. 4(a), and becomes the television signal synthesized according to the present invention.

The multiplexed signal is not limited to analog signals, but may also be digital signals.

FIG. 5 is a block diagram showing details of the orthogonal modulation circuit 4 of FIG. 1. 21 is a normal video signal input terminal, 22 is an amplitude modulator, 23 is a first filter, 24 is an oscillator, 25 is a phase shifter, 26 is a multiple signal input terminal, 27 is a positive modulation circuit, 2
8 is a negative modulation circuit, 29 is a selection circuit, 30 is a second filter, 31 is an adder, and 32 is a composite television signal output terminal. A carrier wave P1 obtained from an oscillator 24 is amplitude-modulated by an amplitude modulator 22 using a normal video signal inputted from a normal video signal input terminal 21. The obtained amplitude modulated wave is band-limited by the first filter 23 to form a residual sideband, and then added to the adder 29. Carrier wave P1 obtained from oscillator 24
The carrier wave P2 is obtained by shifting the phase of the signal by 90 degrees by the phase shifter 25. With the multiplexed signal input from the multiplexed signal input terminal 26, the carrier wave P2 is subjected to positive modulation in both side band amplitude by the positive modulation circuit 27, and negatively modulated by the negative modulation circuit 28. Note that the phase shift direction of the phase shifter 25 may be fixed, but it may also be changed, for example, every -horizontal scanning period. The modulated signals are alternately selected by the selection circuit 29 for each horizontal period or for each field. The timing necessary for this control is supplied from the timing control circuit 5 shown in FIG. In order to synchronize with the receiving side, a control signal may be inserted, for example, during the vertical retrace period. The selected signal is band-limited by a second filter 30 and then added to an adder 31 . The output of adder 31 becomes a composite television signal. That is, the multiplexed signal is superimposed and synthesized on the normal video signal to form a television signal. Note that due to the frequency characteristics of the second filter 28, the multiplexed signal becomes a signal having a band as shown in FIG. 4 (bl).

Next, the timing control circuit 5 outputs horizontal and vertical synchronization signals and controls each circuit.

Since images at both ends of the screen are generally considered to have a lot of correlation in the vertical direction, it is considered that the overall correlation can be reduced by inverting the modulation every -line or every field. In other words, if there is crosstalk due to multiplexed signals on the receiver side, it will be easy to notice if the shape of the multiplexed image is visible, but if the shape is distorted, it will be difficult to notice, so it is better to eliminate the correlation as much as possible. It is thought that if positive modulation and negative modulation are alternately manipulated, the output due to crosstalk will be reversed in a short spatial frequency or time, making it less noticeable due to the characteristics of the eye.

Next, a television signal receiving device on the receiving side in an embodiment of the present invention will be described. FIG. 6 is a block diagram illustrating a television signal receiving device on the receiving side according to an embodiment of the present invention. 61 is a reception demodulation circuit, 62 is a time axis compression circuit 1, 63 is a time axis compression circuit 2, 64 is a wide aspect synthesis circuit, 65 is a display, and 66 is a restoration timing control circuit. 40 is a transmission synthesis television signal, 41 is a demodulated normal video signal, 42 is a restored image both-end video signal, 43 is a restored wide aspect video signal, and 44 is a restored left and right position control signal.

As an embodiment of the present invention, a transmitted television signal 40 synthesized and transmitted is subjected to orthogonal detection in a reception demodulation circuit 61 to obtain a demodulated normal video signal 41 and a restored screen both-end video signal 42 as a demodulated multiplexed signal. The demodulated normal video signal 41 compresses the time axis to 415, contrary to the transmission side, and restores the restored screen both ends video signal 42
are compressed to 1/4 and synthesized, resulting in a restored wide aspect video signal 43, which is displayed as a television screen on a display 65 using, for example, a CRT with an aspect ratio of 5:4.

Each block will be explained in detail below.

First, the reception demodulation circuit 61 shown in FIG. 6 will be explained. In the following, we will take the case of terrestrial broadcasting as an example. A multiplex signal demodulation method on the receiving side in an embodiment of the present invention will be described. The video intermediate frequency band signal output from the tuner is shown in Figure 7 (a).
), the video baseband signal is band-limited using a filter so that it becomes a double-sided band. If this is expressed as a vector, it will look like Figure 7 (bl).Here, 1) is the video carrier wave of the video baseband signal, and I2 is the carrier wave of the multiplexed signal.1)
This is a carrier wave that has the same frequency as , but a phase difference of 90 degrees.

Since the multiplexed signal has residual sidebands when considering the carrier wave 2 as the center, the upper and lower sidebands become vectors bu and bβ, and when decomposed into orthogonal vectors, they become vectors bl and b2.

Furthermore, since the video baseband signal becomes substantially double-sided band waves due to the filter, if the upper and lower side bands are vectors au and aA, their combined vector is al, and only the component orthogonal to vector 2 is present. That is, when synchronously detecting the carrier wave I2, orthogonal distortion due to the vector al and bl components does not occur,
Only multiplexed signal components can be demodulated. Next, we will discuss the demodulation of the main signal. The main signal limits the video intermediate frequency band signal as shown in Figure 7 (C1. That is, the video carrier ■1
At this point, the amplitude is attenuated by 6 dB, resulting in a Nyquist filter characteristic having almost symmetrical amplitude characteristics with respect to the video carrier wave (1). On the other hand, as shown in FIG. 4 (bl), if the multiplexed signal is band-limited by a filter with a frequency characteristic opposite to that of the video intermediate frequency filter of the receiver,
The multiplexed signal components shown in the shaded area in FIG. 7(C) are substantially double-sided bands. When this is expressed as a vector, it becomes as shown in FIG. 7 Tdl. Since the video baseband signal has residual sidebands when considering carrier wave II as the center, the upper and lower sidebands become vector au and vector all, and when decomposed into orthogonal vectors, they become vector al and vector a2. Also, since the multiplexed signal has almost both sidebands, the upper and lower sidebands are vector bu.

Vector b! If so, their combined vector will be b2, which will contain only the component orthogonal to vector 1. That is, when carrier wave 1 is used for synchronous detection, vector a2. Orthogonal distortion due to the b2 component does not occur, and interference due to multiplexed signals to current television receivers that perform video synchronous detection does not occur in principle.

FIG. 7(e) is an example of a block diagram of a reception demodulation circuit 61 of a television receiver that demodulates the multiplexed signal shown in FIG. 6. 131 is an antenna, 132 is a tuner, 133 is a video intermediate frequency filter, 134 is a video detector, 135 is a carrier regeneration circuit, 137 is a filter, 138 is a phase shifter,
139 is a positive demodulation circuit, 140 is a negative demodulation circuit, and 141 is a demodulation selection circuit. A signal sent from the transmitting side is received by an antenna 131, frequency-converted to an intermediate frequency band by a tuner 132, and band-limited by a video intermediate frequency filter. The band-limited signal is supplied to a video detector 134 and a carrier recovery circuit 135.

The carrier wave regeneration circuit 135 regenerates carrier wave 1 for synchronous detection. The carrier wave can be accurately reproduced based on the retrace period in which multiplexed signals are not superimposed. The band-limited signal is detected by the video detector 134 using the carrier wave 1, and becomes a video baseband signal. Further, the output of the tuner 132 is band-limited by a filter 137 as shown in FIG. 7 (al).

A carrier wave I2 obtained by shifting the phase of the carrier wave ■1 obtained from the carrier wave regeneration circuit 135 by 90 degrees by a phase shifter 138 is used to convert the band-limited signal to the positive demodulation circuit 139 and the negative demodulation circuit 14.
Synchronous detection is performed at 0.

The demodulation selection circuit 141 selects the detection output alternately for each horizontal period or each field depending on the transmitting side, and a restored screen both-ends video signal 42 is obtained as a demodulated multiplexed signal. The necessary timing control signal is provided by the restoration timing control circuit 6 shown in FIG.
Supplied from 6.

As described above, in the reception demodulation circuit 61 for multiplexed signal demodulation, not only the normal video signal (video baseband signal) but also the multiplexed signal can be extracted without orthogonal distortion by filtering and synchronous detection using the video carrier wave I2. can.

In addition, in the current PLL synchronous detection system and carrier wave regeneration system receiving and demodulating circuit, multiplexed signals are almost canceled by performing synchronous detection using the video carrier wave 1) as described above.
Interference due to multiplexed signals hardly occurs. However, in the old-style envelope detection type receiving and demodulating circuit, since the vectors are not separated as described above, crosstalk occurs between the main signal and the multiplexed signal, which appears as interference on the screen. However, in the present invention, there is no visible force.

Next, the time axis compression circuit 162, time axis compression circuit 263, and wide aspect synthesis circuit 64 will be explained. The input image of the time axis compression circuit 162 is as shown in FIG. 3(fb), the input of the time axis compression circuit 263 is as shown in FIG. 3(C), and the output of the wide aspect synthesis circuit 64 is as shown in FIG. 3(a). This is a restored wide aspect video signal 43. Restoration is performed by performing the operation opposite to that on the sending side shown in FIGS. 2 and 3. The restored signal is displayed on a screen that is wider than usual.

It goes without saying that the left and right widths of the signals added to both sides can be controlled as necessary using, for example, the restored left and right position control signal 44 superimposed on the vertical retrace period as described above.

Next, the restoration timing control circuit 66 outputs horizontal and vertical synchronization signals and controls the timing of each circuit.

Effects of the Invention As is clear from the above explanation, by superimposing video signals on both sides of the screen with a horizontally elongated screen aspect ratio within the band of a television signal subjected to vestigial sideband amplitude modulation, the correctness of the superimposed signal is By alternately inverting modulation and negative modulation, it is possible to obtain a compatible television signal with no visible interference even when received by an older envelope detection type television receiver. In addition, we provide a television system that allows a dedicated receiver to extract multiplexed signals without orthogonal distortion and expand the aspect ratio, allowing you to enjoy a realistic and powerful screen, and from the perspective of effective use of radio wave resources. However, it is very effective.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a television signal transmitting device on the transmitting side in an embodiment of the present invention, FIG. 2 is a waveform diagram explaining a wide aspect video signal, and FIG. 3 is a diagram explaining processing of a wide aspect video signal. 4 is a spectrum diagram for explaining a television signal subjected to residual sideband amplitude modulation. FIG. 5 is a block diagram of a quadrature modulation circuit.
FIG. 7 is a block diagram illustrating a television signal receiving apparatus on the receiving side according to an embodiment of the present invention, and FIG. 7 is a spectral diagram, a vector diagram, and a block diagram of a reception demodulation circuit. 1... Time axis video signal extraction circuit, 2...
... Time axis expansion circuit 1.3... Time axis expansion circuit 2.4... Quadrature modulation circuit, 61...
Reception demodulation circuit, 62...Time axis compression circuit 1.6
3...Time axis compression circuit 2.64...Wide aspect synthesis circuit. Name of agent Patent attorney Toshio Nakao 1 person Figure 2 Figure 3 Figure 4 Pl-Eiden Karusawa S-Responsibility and N is similar■ Figure 7 12-1 Sent 7 C -Ichishikibetsu 8 Missing S-Eleven Ago Ichi is sent to ice-Ago P-Mitsuenno

Claims (2)

[Claims] (1) Equipped with a time-axis video signal extraction circuit, a time-axis expansion circuit, and an orthogonal modulation circuit, which has the same frequency as the carrier wave and a phase of ±90 degrees within the band of the residual sideband amplitude-modulated television signal. The orthogonal modulation circuit generates and transmits a signal in which a different carrier wave is modulated with a multiplexed signal different from the television signal, and the multiplexed signal has a screen aspect ratio created by the time-axis video signal extraction circuit and the time-axis expansion circuit. It is a video signal on both sides of the screen to make the ratio horizontally elongated, and the orthogonal modulation circuit is provided with a positive modulation circuit and a negative modulation circuit, and positive modulation and negative modulation are performed alternately for each horizontal scanning line or for each field. A television signal transmitting device characterized by: (2) The orthogonal modulation circuit is equipped with a Nyquist filter,
The signal modulated by the multiplexed signal is amplitude-modulated in both sidebands by the multiplexed signal, attenuated by half at the carrier frequency, and made into a vestigial sideband by the Nyquist filter having amplitude characteristics symmetrical with respect to the carrier frequency. The television signal transmitting apparatus according to claim 1, wherein the television signal transmitting apparatus is characterized in that the signal is a signal that does not correspond to a single signal.