JP3070504B2 - Multiplex signal reproduction apparatus, multiple signal transmission method, and multiple signal transmission apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex transmission system, and more particularly to a multiplex signal transmission method for multiplexing and transmitting other information to a current television signal, and a multiplexing method for multiplexing and transmitting another signal to a current television signal. The present invention relates to a signal transmission device and a multiplex signal reproduction device that receives a multiplexed transmission signal.

[0002]

2. Description of the Related Art Conventionally, as a method of multiplexing other information with a television signal, as described in Japanese Patent Application Laid-Open No. 63-36694, a quadrature carrier having a quadrature phase relationship with a video carrier is used as another information. 2. Description of the Related Art A quadrature modulation method in which a modulated signal is combined with a video carrier modulated by a video signal and transmitted is known.

[0003] On the other hand, the 1989 National Convention of the Institute of Television Engineers, pp. 307 to 308 13-12
Examination and experiment of wide aspect image transmission system, and 1
As described in pp. 359 to 360 of the 990 Annual Conference of the Institute of Television Engineers of Japan, 21-1 Comparison of various widening systems from current receivers, the 2nd generation E
A wide aspect of a television screen is being studied as a DTV. Various widening methods are letter box method,
It can be roughly divided into the side panel method and the intermediate method,
Here, the letterbox system related to the present invention will be briefly described with reference to FIG. FIG. 3 is a schematic diagram of a television screen in which the horizontal direction indicates the horizontal scanning direction and the vertical direction indicates the vertical scanning direction. Reference numeral 301 denotes an upper mask portion, 302 denotes a lower mask portion, and 303 denotes a television image display portion. The 16: 9 wide aspect image will be displayed in some form on the display of the current 4: 3 aspect NTSC receiver, and the letterbox method is considered as one of the display methods. The letterbox method is a method in which the left and right sides of a wide aspect image are displayed on a full screen as a display portion 303 and the upper and lower mask portions 301 and 302 are blank as shown in FIG.

[0004] One method of realizing the letterbox method is described in "Prototype Production of 21-8 Letterbox Type Wide EDTV Encoder / Decoder" in the 1990 Annual Conference of the Institute of Television Engineers of Japan, pp. 373-374. According to this, the vertical and temporal auxiliary signals are multiplexed and transmitted to the upper and lower mask portions and the luminance and horizontal high-definition information are multiplexed to the display portion, so that the dynamic resolution and the horizontal resolution are improved simultaneously with the widening.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a quadrature carrier having a quadrature phase relationship with a video carrier is modulated by other information (hereinafter, referred to as a quadrature multiplex signal), and the video modulated by a letterbox video signal is modulated. The present invention relates to a quadrature modulation method for combining and transmitting a carrier wave.

In this quadrature modulation method, crosstalk occurs between the orthogonal multiplexed signal and the video signal due to an imbalance in the characteristics of the filters on the transmission side and the reception side, a shift in the detection axis of the receiver, and a ghost failure. .

An object of the present invention is to provide an optimum multiplex signal transmission method, a multiplex signal transmission device thereof, and a multiplex signal reproduction device for receiving the same when a letterbox system and a quadrature modulation system are used together.

[0008]

Means for Solving the Problems In order to achieve the above-mentioned object, the following configuration is adopted.

In order to reduce a hue change on a screen of a television receiver of an envelope detection system caused by a phase variation of a video signal carrier generated by multiplexing an orthogonal multiplex signal with an orthogonal component, the orthogonal multiplex signal is In a transmission system in which the same orthogonal multiplexed signal is transmitted in an opposite phase relationship between adjacent horizontal scanning periods by repeating a video signal in units of horizontal scanning lines, the reverse phase transmission is canceled by the upper and lower mask portions of the letterbox system. Corresponding to this, the correlation demodulation is canceled in the upper and lower mask portions of the letter box system on the receiving and reproducing side.

According to the present invention, a hue change on the screen of an envelope detection type television receiver caused by a phase variation of a video signal carrier caused by multiplexing an orthogonal multiplex signal with an orthogonal component in a mask portion is reduced. Since there is no necessity, it is not necessary to repeatedly transmit the orthogonal multiplex signal in the mask portion in units of horizontal scanning lines of the video signal and to transmit the same orthogonal multiplex signal in an opposite phase relationship between adjacent horizontal scanning periods.
Thereby, the data rate that can be transmitted can be improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a multiplex signal reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an embodiment of the multiplex signal transmission apparatus of the present invention for transmitting a signal received by the multiplex signal reproduction apparatus of FIG. First, FIG. 2 will be described.

Reference numeral 201 denotes an audio signal input terminal, and 202 denotes FM.
Modulator 203, a primary color signal input terminal, 204 a synchronization signal input terminal, 205 a matrix circuit, 206 a luminance signal processing circuit, 207 a color difference signal processing circuit, 207 a synthesis circuit, 209 a video modulator, 210 a residual A transmission VSB filter for sideband amplitude modulation, 211 is an orthogonal multiplexed signal input terminal, 212 is a video signal carrier generator, 213 is a phase shifter,
214 is a modulator for orthogonal multiplexed signals, 215 is a gain adjustment circuit, 216 is an equalizer, 217 and 218 are adders, 2
19 is an upconverter for tuning, 220 is an antenna,
221 is a mask part detection circuit, 901 is a signal processing circuit,
1301 is a ternary conversion circuit and 1302 is a line correlation circuit.

The audio signal from the audio signal input terminal 201 is FM-modulated by an FM modulator 202. The RGB three primary color signals input from the primary color signal input terminal 203 are separated into a luminance signal and a color difference signal by a matrix circuit 205 and processed by a luminance signal processing circuit 206 and a color difference signal processing circuit 207, respectively. The synchronizing signal is synthesized by the synthesizing circuit 208 at the timing of the synchronizing signal to obtain a letterbox video signal. The carrier from the video signal carrier generator 212 is converted to the video modulator 20 by this video signal.
9 and the transmission VSB filter 210 limits the band to the television broadcast band. Thereafter, the adder 218
Then, the modulated sound wave is added, the channel is selected by the up-converter 219 and transmitted from the antenna 220.

On the other hand, an orthogonal multiplexed signal to be multiplexed from an input terminal 211 is added to a signal processing circuit 901, and the signal processing circuit 901 applies important signals to upper and lower mask portions of the letterbox system detected by the mask portion detection circuit 221. , For example, upper bits such as the MSB side of data, PCM
The compression range data, error correction code, data synchronization signal, and the like are arranged. An output signal of the signal processing circuit 901 is input to a ternary conversion circuit 1301.

The ternary conversion circuit 1301 has a function of +1, 0, -1.
The line correlation circuit 1302 converts the converted ternary signal into a mask part detection circuit 221.
Is subjected to line correlation processing and output to the next stage.

The carrier of the video signal, which has been phase-shifted by 90 degrees with the signal via the phase shifter 213, is modulated by the modulator 214 to obtain a quadrature modulated signal. Here, based on the synchronization signal input from the synchronization signal input terminal 204, the timing indicating the upper and lower mask portions of the letterbox system is determined by the mask portion detection circuit 221.
The gain adjustment circuit 215 switches the gain of the quadrature modulation signal between the mask portion and the display portion as a control signal.
The output of the gain adjustment circuit 215 corrects the frequency characteristic by an equalizer 216 having the inverse characteristic of the Nyquist filter of the video signal IF, and adds the output to the carrier modulated by the video signal by the adder 217. As a result, the carrier for video is modulated in an orthogonal relationship with the video signal of the letterbox system and the orthogonal multiplexed signal.

Here, the line correlation processing will be described.

The line correlation is used to reduce a hue change on a screen of a television receiver of an envelope detection system caused by a phase variation of a video signal carrier caused by multiplexing an orthogonal multiplex signal with an orthogonal component. This is a transmission method in which an orthogonal multiplex signal is repeated in units of horizontal scanning lines of a video signal and the same orthogonal multiplex signal is transmitted in an opposite phase relationship between adjacent horizontal scanning periods.
In response to the timing from 21, the reverse phase transmission is canceled by the upper and lower mask portions of the letterbox system. This is because it is not necessary to reduce the hue change on the screen of the envelope detection type television receiver caused by the phase variation of the video signal carrier wave caused by multiplexing the orthogonal multiplex signal on the orthogonal component in the mask portion. is there.

FIG. 4 shows a transmission pattern of the embodiment of FIG. FIG. 4 simulates the data transmission timing in accordance with the television screen, and the same reference numerals as those in FIG. 3 denote the same parts. In FIG. 4, the horizontal direction indicates the horizontal scanning direction, and the vertical direction indicates the vertical scanning direction. Time-series data is transmitted in the horizontal scanning period, such as data A0 to A9 and data B0 to B9. Here, the upper mask portion 30
1 and the lower mask portion 302, the data in the upper and lower horizontal scanning periods are independent, but in the display portion 303, for example, the data E0 to E9 are the same data having the opposite phases in the upper and lower horizontal scanning periods.

According to the embodiment of FIG. 2, there is an effect that the data rate that can be transmitted can be improved by performing the transmission as shown in FIG.

Next, the blocks of the multiplex signal reproducing apparatus shown in FIG. 1 will be described.

Reference numeral 101 denotes an antenna, 102 denotes a high-frequency amplifier circuit, 103 denotes a frequency conversion circuit, 104 denotes a local oscillation circuit,
105 is a tuning control circuit, 106 is a Nyquist filter,
107 is a video detection circuit, 108 is an audio signal detection circuit, 1
09 is an audio signal output terminal, 110 is a video signal output terminal,
111 is a band pass filter (hereinafter abbreviated as BPF), 11
2 is a synchronous detection circuit, 113 is a gain control circuit, 114 is a multiplexed signal output terminal, 115 is a synchronization detection circuit, 116 is a mask part detection circuit, 601 and 602 are comparison circuits, 605 is a digital signal decoding circuit, and 1001 is signal processing. Circuit, 1
002 and 1003 are reference signal generation circuits, 1501 is a switch circuit, 1502 is a subtraction circuit, 1503 is a delay circuit,
1504 is a correlation demodulation circuit, and 1505 is a binary conversion circuit.

A television signal input from an antenna 101 is amplified by a high-frequency amplifier circuit 102 and frequency-converted in a frequency conversion circuit 103 by a signal from a local oscillation circuit 104. At this time, the tuning is performed by converting the signal frequency of the local oscillation circuit 104 by the tuning control circuit 105.

Next, the signal output from the frequency conversion circuit 103 is input to a Nyquist filter 106, where a required band is extracted. The signal output from the Nyquist filter 106 is demodulated by the video detection circuit 107,
A video signal is obtained at a video signal output terminal 110. at the same time,
An audio carrier of the television signal whose frequency has been converted to 4.5 MHz is extracted and input to the audio detection circuit 108. Then, FM detection is performed, and an audio signal is obtained at an audio signal output terminal 109.

Here, the demodulated video signal which is the output of the video detection circuit 107 is of a letterbox system, and this video signal is input to a synchronization detection circuit 115 to reproduce a horizontal synchronization signal, a vertical synchronization signal, etc. These are input to the mask part detection circuit 116 to obtain a timing signal indicating the upper and lower mask parts of the letterbox system.

On the other hand, the signal output from the frequency conversion circuit 103 extracts a necessary band by the BPF 111 and demodulates the orthogonal multiplexed signal by the synchronous detection circuit 112. And
It is input to the gain control circuit 113 of the next stage.

The gain control circuit 113 controls the quadrature multiplex signal demodulated by the synchronous detection circuit 112 in response to the timing signal indicating the upper and lower mask portions of the letterbox system from the mask portion detection circuit 116, and outputs the quadrature signal having a constant amplitude. Outputs a multiplex signal. The quadrature multiplex signal having the constant amplitude is input to the switch circuit 1501, the subtraction circuit 1502, and the delay circuit 1503.

The switch circuit 1501 is controlled by the mask portion detection circuit 116. When the line correlation processing is performed, that is, the display part 3 of the letter box method
During the period 03, the switch circuit 1501 is closed toward (b), and the subtraction circuit 1502 and the delay circuit 1503 are connected.
By performing the subtraction processing, the transmitted data is doubled, and the white noise is only increased by a factor of √2. Further, interference from an image having a large correlation every horizontal period such as an image ghost can be canceled and removed. When the line correlation processing is not performed, that is, the upper and lower mask portions 3 of the letter box method
Between 01 and 302, the switch circuit 1501 is closed toward (a), and the subtraction circuit 1502 and the delay circuit 1503 are disconnected from the connection.

The output of the switch circuit 1501 is set to +1, 0,
In order to identify the value as -1, the comparator 601 determines that the output of the reference signal generating circuit 1002 is larger than +1, and the comparator 602 determines that the output of the reference signal generating circuit 1003 is smaller than -1. A data strobe and a digital signal decoding process are performed to detect a ternary signal. This ternary signal is input to the correlation demodulation circuit 1504.

The correlation demodulation circuit 1504 demodulates the line correlation process. The correlation demodulation circuit 1504 performs the correlation demodulation on the upper and lower mask portions of the letterbox system according to the timing signal indicating the upper and lower mask portions of the letterbox system from the mask portion detection circuit 116. Try to cancel. Correlation demodulation circuit 150
The digital ternary output signal of 4 is converted to a binary conversion circuit 1505
Is input to The binary conversion circuit 1505 converts a digital ternary into a digital binary, and outputs it to the signal processing circuit 1001.

The signal processing circuit 1001 detects the upper and lower mask portions of the coded digital signal by the mask portion detection circuit 116 in the letter box system, decodes the data accordingly, and obtains a multiplexed signal at the output terminal 114. .

Here, the gain control circuit 113 of FIG.
The gain adjustment circuit 215 operates as follows.

When the mask portion multiplexed signal is not multiplexed in the mask portion, there is no problem even if the crosstalk from the orthogonal multiplexed signal in the mask portion is slightly increased. Increase the multiplex level of the multiplex signal. In response to this, on the multiplex signal reproducing device side, the gain control circuit 113 reduces the orthogonal multiplex signal gain in the mask portion and controls the gain so as to have a constant amplitude.

On the other hand, when the mask portion multiplexed signal is multiplexed in the mask portion, in order to reduce crosstalk from the orthogonal multiplexed signal in the mask portion, the gain adjustment circuit 215 on the multiplex signal generator side generates the orthogonal multiplexed signal. Reduce multiplex levels. In response to this, on the multiplex signal reproducing device side, the gain control circuit 113 increases the gain of the orthogonal multiplex signal in the mask portion and controls the gain so that the amplitude becomes constant.

Thus, when both the letterbox system and the quadrature modulation system are used, multiplexing optimal for both systems can be performed.

In the embodiment shown in FIG. 1, there is an effect that the operating frequency band of the gain control circuit 113 can be set to the base band.

In the embodiment shown in FIG. 2, since the gain adjustment circuit 215 is arranged at the subsequent stage of the modulator 214, there is an effect that the operation of the modulator 214 is not burdened.

In the embodiment shown in FIGS. 1 and 2, there is an effect that a digitally encoded orthogonal multiplex signal can be identified at an optimum level. Although the ternary digital signal is shown in the embodiment of FIG. 1, in general, in the case of an n-value digital signal, if n-1 comparison circuits and a reference signal generation circuit are provided, the case of FIG. It can be configured similarly.

Further, according to the embodiments shown in FIGS. 1 and 2, since the degree of modulation of the video signal is low in the mask portion, crosstalk from the video signal to the orthogonal multiplex signal is reduced, and the error rate of the orthogonal multiplex signal is reduced. Therefore, by multiplexing the important signal in the mask portion, there is an effect that the error correction capability and the error correction capability are high, and a stable reception / reproduction operation can be performed.

Further, in the embodiment shown in FIGS. 1 and 2, there is an effect that the interference from the video can be reduced during the display portion 303 of the letterbox system, and the receivable data rate can be further improved.

[0042]

According to the present invention, a quadrature modulation method for modulating a quadrature carrier having a quadrature phase relationship with a video carrier with a quadrature multiplex signal, combining the modulated carrier with a video carrier modulated with a letterbox video signal, and transmitting the resultant signal. When the letterbox method and the quadrature modulation method are used in combination as described above, attention is paid to the fact that crosstalk occurs between the letterbox method video signal and the orthogonal multiplexed signal, and the following effects are obtained.

In the mask portion, it is not necessary to reduce the hue change on the screen of the television receiver of the envelope detection system caused by the phase fluctuation of the video signal carrier caused by multiplexing the orthogonal multiplexed signal on the orthogonal component. In the mask portion, the orthogonal multiplexed signal is repeated in units of horizontal scanning lines of the video signal, and it is not necessary to transmit the same orthogonal multiplexed signal in an opposite phase relationship between adjacent horizontal scanning periods, thereby improving the data rate that can be transmitted. Therefore, there is an effect that an optimum multiplex signal transmission method, a multiplex signal transmission device thereof, and a multiplex signal reproduction device receiving the same can be configured.

[Brief description of the drawings]

FIG. 1 is a block diagram of a multiplex signal reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a multiplexed signal generator showing one embodiment of the present invention.

FIG. 3 is a schematic diagram of a letter box type screen.

FIG. 4 is a schematic diagram of a screen pattern of a transmission signal according to the present invention.

[Explanation of symbols]

 113: gain control circuit, 115: synchronization detection circuit, 116: mask part detection circuit, 215: gain adjustment circuit, 221: mask part detection circuit, 601: comparison circuit, 602: comparison circuit, 901: signal processing circuit, 1001: Signal processing circuit, 1302 line correlation circuit, 1501 switch circuit, 1502 subtraction circuit, 1503 delay circuit.

Continuation of front page (72) Inventor Kazuo Nakagawa 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Within Hitachi Media Media Research Laboratories, Inc. (56) References JP 1-2261979 (JP, A) JP JP-A-62-98883 (JP, A) JP-A-63-240195 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 7/025 7/088 H04J 11/00

Claims (3)

(57) [Claims] (1)4: 3 Aspect with vestigial sideband amplitude modulation
Table with a wide-aspect image in the center of the
And the upper and lower parts of the 4: 3 aspect screen
Upper mask part and lower mask part where parts are masked with a single color
And a carrier orthogonal to the video carrier of the video signal composed of
A transmission signal in which another signal is multiplexed and transmitted by a wave, and
The transmission signal is multiplexed and the another signal is horizontally scanned by a video signal.
Invert multiple times for each multiple of the period and repeat and transmit
And the other signal to be multiplexed is repeated.
And a general transmission period for transmitting data without returning.
The period of the mask portion or the period of the lower mask
A general transmission period, and the period of the display portion is the repetition of the reversal.
Receives and reproduces a transmission signal multiplexed as a transmission period
Multiplex signal reproducing device,  The multiplex transmission is performed by detecting the orthogonal carrier.
Synchronous detection means for outputting a signal ofThe display portion and the upper mask portion or the lower mask portion
Detects minute and outputs timing signal to identify detected part
Detecting means for Delay means for delaying another signal which is the output of said synchronous detection means
Steps and The output signal of the delay means and the output of the synchronous detection means.
Subtraction processing with another signal is performed during the inversion repetition transmission period.
Subtraction means for outputting a correlation demodulated signal Using the timing signal output by the detection means
The period of the upper mask portion or the lower mask portion.
The period is the output of the synchronous detection means in the first half of the general transmission period.
Select another signal and repeat the inversion cycle during the display period.
The correlation demodulation being an output of the subtraction means during a return transmission period
Switching means for outputting a signal,  A multiplexed signal reproducing device comprising: (2)4: 3 Aspect with vestigial sideband amplitude modulation
Table with a wide-aspect image in the center of the
And the upper and lower parts of the 4: 3 aspect screen
Upper mask part and lower mask part where parts are masked with a single color
And a carrier orthogonal to the video carrier of the video signal composed of
Multiplex signal transmission method of multiplex transmission of another signal by wave so
So,  Multiplex the another signal to an integer of the horizontal scanning period of the video signal
Multiple per double periodRoundaboutInverted repeat to repeat and transmit
A return transmission period and a general transmission in which the another signal to be multiplexed is transmitted without repetition.
The sending periodPossess,The period of the upper mask portion or the period of the lower mask portion
Is the general transmission period, and the period of the display portion is
Characterized by multiplex transmission as a repetitive transmission period
Multiple signal transmission method. (3)4: 3 Aspect with vestigial sideband amplitude modulation
Table with a wide-aspect image in the center of the
And the upper and lower parts of the 4: 3 aspect screen
Upper mask part and lower mask part where parts are masked with a single color
And a carrier orthogonal to the video carrier of the video signal composed of
A multiplex signal transmission device that multiplexes and transmits another signal using waves.
hand,  Multiplex the another signal to an integer of the horizontal scanning period of the video signal
Inversion repeater that repeats and transmits repeatedly multiple times every double period
Correlation means for creating a return transmission period, and said another signal to be multiplexed
Uncorrelated hands that make the general transmission period to transmit without repeating
Steps andThe period of the upper mask portion or the period of the lower mask portion
Is the general transmission period, and the period of the display portion is
Control means for controlling as a repetition transmission period.
thing A multiplex signal transmission device characterized by the above-mentioned.