JPH0522707A - Reproducer for transmitting signal - Google Patents

Abstract

PURPOSE:To stably receive and reproduce a multiplexing signal from a transmitting signal obtained by orthogonally modulating the video signal and multiplexing signal of a letter box system, etc. CONSTITUTION:The video signal is inputted to a synchronization detecting circuit 115 so as to reproduce a horizontal synchronizing signal, etc., and a mask part detecting circuit 116 detects the upper and lower mask parts of the letter box system from the signal. During that period, a signal reproducing circuit 117 reproduces a clock signal, etc., and a signal processing circuit 113 processes the multiplexing signal demodulated by a synchronous detection circuit 112. Thus, the horizontal synchronizing signal, the clock signal, carrier wave, etc., are stably reproduced by utilizing that the modulation degree of the video signal is low in the mask part so that a transmitting signal reproducer which is little influenced by a ghost or the video signal is effectively constituted.

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 receiver for multiplexing other information on a current television signal and receiving the multiplexed transmission signal.

[0002]

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

On the other hand, the 1989 National Conference of the Television Society of Japan, pages 307 to 308, 13-12.
Wide aspect image transmission system study and experiment, and 1
2nd Generation E, as described in Page 359 to 360 of the 990 Annual Conference of the Television Society of Japan 21-1 Comparison of various widening systems from the viewpoint of the current receiver
A wide aspect of a TV screen is being studied as a DTV. Various widening methods are letterbox,
It can be roughly divided into side panel type and intermediate type,
Here, the letter box method related to the present invention will be briefly described with reference to FIG. FIG. 4 is a simulated view of a television screen in which the horizontal direction is the horizontal scanning direction and the vertical direction is the vertical scanning direction. 401 is an upper mask portion, 402 is a lower mask portion, and 403 is 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 in full screen as a display portion 403 and the upper and lower mask portions 401 and 402 are blank portions as shown in FIG.

One method for realizing this letterbox method is described in References 1973 to 374 pages 21-8 Letter Box Wide EDTV Encoder / Decoder Prototype of the 1990 Annual Conference of the Television Society of Japan. According to this, the vertical-time auxiliary signal is multiplexed in the upper and lower mask portions, and the luminance horizontal high-definition information is multiplexed in the display portion, so that the dynamic resolution and the horizontal resolution are improved at the same time as widening.

Further, a report combining the letterbox system and the quadrature modulation system was reported in Technical Report Vol. 15, No. 32 pages 7 to 12 This is described in a trial experiment of an EDTV combining a high-quality wide image and digital audio. This report describes a combination of a video signal and a multiplexed signal as shown in (a) and (b) below. (A) A quadrature modulation method in which a quadrature carrier having a quadrature phase relationship with a video carrier is modulated with other information (hereinafter referred to as a multiplexed signal), and is synthesized with a video carrier modulated with a letterbox system video signal for transmission. (B) A quadrature carrier having a quadrature phase relationship with a video carrier is modulated by a multiplexed signal, and vertical-time auxiliary signals are provided in upper and lower mask parts of a letterbox system (hereinafter, a signal to be multiplexed in these mask parts is a mask part multiplexed signal ), A quadrature modulation method in which luminance horizontal high-definition information is combined with a video carrier modulated by a video signal multiplexed and transmitted on the display portion and transmitted.

[0006]

In the above-mentioned prior art combining the letterbox system and the quadrature modulation system, the receiver has not been described in detail. Hereinafter, a receiver that performs stable demodulation will be considered.

In the quadrature modulation method, crosstalk occurs between the multiplex signal and the video signal due to imbalance of the characteristics of the filters on the transmitting side and the receiving side, deviation of the detection axis of the receiver, and ghost interference. Considering these phenomena,
When considering the combined use of the quadrature modulation method and the letter box method or the intermediate method, the following points should be noted.

(1) If the mask portion multiplexed signal is not multiplexed on the mask portion, there is no problem even if the crosstalk from the mask portion multiplexed signal is slightly increased. (2) When the mask portion multiplexed signal is multiplexed on the mask portion, it is desirable that the crosstalk from the mask portion multiplexed signal is small. (3) The degree of modulation of the video signal is low in the mask portion.

It is an object of the present invention to utilize the fact that the degree of modulation of the mask portion is low in the case of a video signal of the letterbox system or the like shown in (3) of the above noted points, and is orthogonal to the letterbox system or the like. Optimal when used in combination with modulation method,
It is an object of the present invention to provide a transmission signal reproducing device which receives a multiplexed signal transmitted by being orthogonally multiplexed with little influence of a ghost or a video signal.

[0010]

In order to achieve the above-mentioned object, the following constitution is adopted. The structure is such that a quadrature carrier having a quadrature phase relationship with a video carrier is modulated with a multiplex signal, and a quadrature multiplex transmission signal transmitted by being combined with a video carrier modulated with a letterbox type video signal is received and reproduced. In the device, a mask part detection means that receives and reproduces a letterbox type video signal and detects the upper and lower mask parts of the letterbox type, and a horizontal synchronizing signal and a clock signal of the digital circuit in the receiver in the upper and lower mask parts. The control signal reproducing means for reproducing or the carrier wave reproducing means for performing carrier wave reproduction for synchronous detection.

[0011]

The mask portion detecting means receives and reproduces the video signal of the letterbox method or the like to detect the upper and lower mask portions of the letterbox method or the like, and the control signal reproducing means or the carrier wave reproducing means horizontally synchronizes the upper and lower mask portions. It reproduces signals and clock signals of digital circuits in the receiver, or reproduces carrier waves for synchronous detection.

Since the mask portion has a low degree of modulation of the video signal, it is less affected by ghosts and changes in the video signal, so that the horizontal synchronizing signal and the clock signal reproduced from the color burst can be stably demodulated and received and reproduced. Since the control signal of the multiplexed signal can be used and the carrier recovery for the synchronous detection can be stably performed, the multiplexed signal can be demodulated stably.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of a transmission signal reproducing apparatus showing an embodiment of the present invention. In FIG. 1, a signal transmitted by quadrature-modulating a letterbox type video signal and a multiplexed signal is received.

In FIG. 1, 101 is an antenna and 102
Is a high frequency amplifier circuit, 103 is a frequency conversion circuit, 104 is 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, 109 is an audio signal output terminal, 110 Is a video signal output terminal, 111 is a band pass filter (hereinafter referred to as BPF).
, 112 is a synchronous detection circuit, 113 is a signal processing circuit, 114 is a multiple signal output terminal, 115 is a synchronization detection circuit, 116 is a mask portion detection circuit, and 117 is a signal reproduction circuit.

A television signal input from the antenna 101 is amplified by a high frequency amplifier circuit 102, and frequency converted by a signal from a local oscillator circuit 104 in a frequency conversion circuit 103. 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 the Nyquist filter 106, and the required band is extracted there. The signal output from the Nyquist filter 106 is demodulated by the video detection circuit 107,
A video signal is obtained at the video signal output terminal 110. at the same time,
The 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 the audio signal output terminal 109.

On the other hand, the signal output from the frequency conversion circuit 103 has a required band extracted by the BPF 111, and the multiplexed signal is demodulated by the synchronous detection circuit 112.

The demodulated video signal output from the video detection circuit 107 is of the letterbox type, and this video signal is input to the sync detection circuit 115 to reproduce a horizontal sync signal, a vertical sync signal, etc. and mask them. Partial detection circuit 116
To obtain a timing signal indicating the upper and lower mask parts of the letterbox system. The signal reproduction circuit 117 reproduces a clock signal or the like in the period of the upper and lower mask portions by this timing signal and outputs it to the signal processing circuit 113. The signal processing circuit 113 uses the output signal of the signal reproduction circuit 117 for the multiplexed signal demodulated by the synchronous detection circuit 112, for example, as a master clock in the case of performing digital processing to perform decoding processing, error correction processing, waveform, etc. Various signal processing such as conversion processing is added, and the multiplexed signal after signal processing is output to the multiplexed signal output terminal 114.

The embodiment of FIG. 1 has an effect that the operation of the signal processing circuit 113 using the clock signal can be stably performed.

An embodiment of the signal reproducing circuit 117 is shown in FIG.

The same reference numerals as those in FIG.
Is a burst extraction circuit, 202 is a phase comparison circuit, 203,
206 is a switch circuit, 204 and 205 are low-pass filters (hereinafter abbreviated as LPF), 207 is a voltage controlled oscillator (hereinafter abbreviated as VCO), 208 is a frequency divider circuit, 209 is a video signal input terminal, and 210 is a mask portion timing. An input terminal 211 is a clock signal output terminal. Phase comparator circuit 202, LPF204 or LPF205, VCO2
07, the frequency dividing circuit 208 constitutes a PLL circuit, and the color subcarrier is reproduced from the burst signal extracted by the burst extracting circuit 201. The VCO 207 oscillates at a frequency that is, for example, four times as high as the color subcarrier, divides it by 4 by the frequency dividing circuit 208, and returns it to the phase comparison circuit 202. At this time, by using the output of the mask portion detection circuit 116, the switch circuits 203, 20
6 is controlled to switch the LPFs 204 and 205 between the letter box type mask portion and the display portion, and the optimum loop characteristics are set in each.

As described above, if the output of the VCO 207 is used as the clock signal, the clock signal can be stably reproduced.

Another embodiment of the signal processing circuit 117 is shown in FIG.

The same reference numerals as those in FIGS. 1 and 2 indicate the same functions,
301 is a sample and hold circuit (hereinafter abbreviated as S / H), 302 is a low-pass filter (hereinafter abbreviated as LPF)
Is.

Since the degree of modulation of the video signal is low in the mask portion, the influence of ghost and changes in the video signal is small. Therefore, in the embodiment of FIG. 3, the output of the mask portion detection circuit 116 is used to extract the information of only the mask portion by the S / H 301 to form the PLL loop, so that the clock signal can be stably reproduced. There is an effect that can be done.

FIG. 5 shows a block diagram of a transmission signal reproducing apparatus which is another embodiment of the present invention. The same reference numerals as those in FIG. 1 indicate the same functions, and 501 is a synchronization detection circuit. In the embodiment of FIG. 5, the synchronization detection operation of the synchronization detection circuit 501 is performed only in the upper and lower mask portions.

FIG. 6 shows an embodiment of the synchronization detection circuit 501. The same reference numerals as those in FIG. 5 indicate the same functions, 601 is a sync separation circuit, 602 is a phase comparison circuit, 603 and 606 are switch circuits, and 604 and 605 are low-pass filters (hereinafter referred to as L
Reference numeral 607 is a voltage controlled oscillator (hereinafter abbreviated as VCO), 608 is a video signal input terminal, 609 is a mask portion timing input terminal, and 610 is a synchronization signal output terminal.

The phase comparison circuit 602, LPF 604 or LPF 605, VCO 607 constitutes a PLL circuit, and the horizontal sync signal is reproduced from the composite sync separated by the sync separation circuit 601. At this time, the output of the mask portion detection circuit 116 is used to switch the switch circuit 60.
3, 606 is controlled to switch the LPFs 604 and 605 between the letterbox type mask portion and the display portion, and the optimum loop characteristics are set in each.

As a result, the horizontal synchronizing signal can be stably demodulated.

Another embodiment of the synchronization detection circuit 501 is shown in FIG. The same reference numerals as those in FIGS. 5 and 6 denote the same functions, and 701
Is a sample and hold circuit (hereinafter abbreviated as S / H), 70
Reference numeral 2 is a low-pass filter (hereinafter abbreviated as LPF).

Since the degree of modulation of the video signal is low in the mask portion, the influence of ghost and changes in the video signal is small. Therefore, in the embodiment of FIG. 7, the output of the mask portion detection circuit 116 is used to extract the information of only the mask portion by the S / H 701 to form the PLL loop, so that the horizontal synchronizing signal can be stably demodulated. There is an effect that can be.

FIG. 8 shows a block diagram of a transmission signal reproducing apparatus which is another embodiment of the present invention. The same reference numerals as those in FIGS. 1 and 5 indicate the same functions, and 801 is a signal processing circuit. In the embodiment of FIG. 8, not only the output signal of the signal reproduction circuit 117,
The signal processing operation of the signal processing circuit 801 is also performed using the output signal of the synchronization detection circuit 501. The output signal of the signal reproduction circuit 117 is used as a master clock when performing digital processing, for example, and the output signal of the synchronization detection circuit 501 is used as a timing signal for signal processing synchronized with the horizontal scanning period, for example, to perform correlation processing during the horizontal scanning period. , Extraction of specific horizontal scanning period and switching of processing, decoding processing, error correction processing,
Various signal processing such as waveform equalization processing is applied, and the multiplexed signal after signal processing is output to the multiplexed signal output terminal 114.

The embodiment of FIG. 8 has an effect that the operation of the signal processing circuit 801 using the clock signal and the synchronizing signal can be stably performed.

FIG. 9 shows a block diagram of a transmission signal reproducing apparatus which is another embodiment of the present invention. The same reference numerals as those in FIGS. 1 and 5 indicate the same functions, and 901 is a signal processing circuit. In the embodiment shown in FIG. 9, the demodulated video signal output from the video detection circuit 107 and the multiplexed signal demodulated by the synchronous detection circuit 112 are input to the signal processing circuit 901. Similar to the case of FIG. 8, the signal processing circuit 901 inputs the output signal of the signal reproduction circuit 117 and the output signal of the synchronization detection circuit 501, performs signal processing such as crosstalk removal or ghost removal, and outputs a video signal. The video signal and the multiplexed signal after the signal processing are output to the terminal 110 and the multiplexed signal output terminal 114, respectively.

The embodiment of FIG. 9 has an effect that the operation of the signal processing circuit 901 using the clock signal and the synchronizing signal can be stably performed.

FIG. 10 shows a block diagram of a transmission signal reproducing apparatus which is another embodiment of the present invention. The same reference numerals as those in FIGS. 1, 5 and 9 indicate the same functions.
Reference numeral 2 is a carrier wave regenerating circuit, 1003 is a low pass filter (hereinafter abbreviated as LPF), and the multiplier circuit 1001, the carrier wave regenerating circuit 1002 and the LPF 1003 are the synchronous detection circuit 11
Make up 2.

In the embodiment of FIG. 10, the carrier wave reproducing operation of the carrier wave reproducing circuit 1002 constituting the synchronous detection circuit 112 is performed only in the upper and lower mask portions.

One embodiment of the carrier recovery circuit 1002 is shown in FIG.
Shown in 1. The same reference numerals as those in FIG.
1 is a quadrature intermediate frequency (hereinafter abbreviated as quadrature IF) signal input terminal, 1102 is a mask partial timing input terminal, 11
Reference numerals 03 and 1106 are switch circuits, 1104 and 1105 are low-pass filters (hereinafter abbreviated as LPF), 1107 is a voltage controlled oscillator (hereinafter abbreviated as VCO), and 1108 is a carrier wave output terminal.

The multiplication circuit 1001, LPF 1104 or LPF 1105, VCO 1107 constitutes a PLL circuit, and a carrier wave is reproduced from the quadrature IF signal. This time,
The output of the mask portion detection circuit 116 is used to control the switch circuits 1103 and 1106 to switch the LPFs 1104 and 1105 between the letter box type mask portion and the display portion to obtain the optimum loop characteristics. The multiplication circuit 1001 also serves as a synchronous detection operation for demodulating a multiplexed signal.

As a result, it is possible to stably reproduce the carrier wave with a simple structure.

Another embodiment of the carrier recovery circuit 1002 is shown in FIG. The same reference numerals as those in FIGS. 10 and 11 indicate the same functions, and 1201 is a sample and hold circuit (hereinafter abbreviated as S / H) and 1202 is a low-pass filter (hereinafter abbreviated as LPF).

Since the degree of modulation of the video signal is low in the mask portion, the influence of ghost and changes in the video signal is small. Therefore, in the embodiment shown in FIG. 12, the mask portion detection circuit 116.
Since the information of only the mask portion is extracted by the S / H 1201 using the output of 1 to form the PLL loop, there is an effect that the carrier wave can be stably reproduced.

FIG. 13 shows a block diagram of a transmission signal reproducing apparatus which is another embodiment of the present invention. The same reference numerals as those in FIG. 1, FIG. 5, FIG. 9, and FIG. 10 indicate the same functions, and 1301 constitutes a carrier wave regenerating circuit. The embodiment of FIG. 13 is a synchronous detection circuit 11
The carrier wave regenerating operation of the carrier wave regenerating circuit 1301 constituting No. 2 is performed only in the upper and lower mask portions.

FIG. 1 shows an embodiment of the carrier recovery circuit 1301.
4 shows. The same reference numerals as those in FIGS. 11 and 13 indicate the same functions, and 1401 is a phase comparison circuit. Phase comparison circuit 14
01, LPF1104 or LPF1105, VCO1
A PLL circuit is constituted by 107, and a carrier wave is reproduced from the orthogonal IF signal. At this time, the mask portion detection circuit 116
The switch circuits 1103 and 1106 are controlled by using the output of the L.
The PFs 1104 and 1105 are switched to have the optimum loop characteristics in each.

Compared with the embodiment of FIG. 11, since the phase comparison circuit 1401 of the carrier wave reproduction PLL circuit can be dedicated, the carrier wave can be reproduced accurately and stably.

Another embodiment of the carrier recovery circuit 1301 is shown in FIG. The same reference numerals as those in FIGS. 11, 12, 13, and 14 indicate the same functions. Since the degree of modulation of the video signal is low in the mask portion, the influence of ghosts and changes in the video signal is small. Therefore, in the embodiment of FIG. 12, the output of the mask portion detection circuit 116 is used to extract the information of only the mask portion by the S / H 1201 to form a PLL loop, and the phase comparison of the carrier reproduction PLL circuit is performed. Circuit 14
Since 01 can be dedicated, there is an effect that a carrier wave can be accurately and stably reproduced.

FIG. 16 shows a block diagram of a transmission signal reproducing apparatus which is another embodiment of the present invention. 1, 5, 9, and 10 indicate the same functions, 1601 is a synchronous detection circuit, 1602 is a carrier recovery circuit, and the synchronous detection circuit 1601 and the carrier recovery circuit 1602 include the video detection circuit 10.
Make up 7.

In the embodiment of FIG. 16, the carrier wave reproducing operation of the carrier wave reproducing circuit 1602 forming the video detection circuit 107 is performed only in the upper and lower mask portions.

One embodiment of the carrier recovery circuit 1602 is shown in FIG.
7 shows. 16 that are the same as those in FIG.
1 is an intermediate frequency (hereinafter abbreviated as IF) signal input terminal, 1
702 is a phase comparison circuit, 1703 and 1706 are switch circuits, 1704 and 1705 are low-pass filters (hereinafter referred to as L
PF, 1707 is a voltage controlled oscillator (hereinafter referred to as VCO).
1708 is a π / 2 phase shift circuit, 1709 is a mask partial timing input terminal, and 1710 is a carrier wave output terminal.

The phase comparison circuit 1702, LPF 1704 or LPF 1705, VCO 1707, and π / 2 phase shift circuit 1708 form a PLL circuit, and reproduce the carrier wave from the IF signal. At this time, the output of the mask portion detection circuit 116 is used to control the switch circuits 1703 and 1706, and the LP is used in the mask portion and the display portion of the letterbox method.
F1704 and 1705 are switched to obtain the optimum loop characteristic in each.

As a result, the carrier wave can be stably reproduced.

Another embodiment of the carrier recovery circuit 1602 is shown in FIG. The same reference numerals as those in FIGS. 16 and 17 indicate the same functions, and 1801 is a sample and hold circuit (hereinafter abbreviated as S / H) and 1802 is a low-pass currency filter (hereinafter abbreviated as LPF).

Since the mask portion has a low degree of modulation of the video signal, it is less affected by ghost and changes in the video signal. Therefore, in the embodiment shown in FIG. 18, the mask portion detection circuit 116.
The information of only the mask portion is extracted by the S / H 1801 using the output of 1 to form the PLL loop, so that there is an effect that the carrier wave can be stably reproduced.

[0054]

According to the present invention, (a) a quadrature carrier having a quadrature phase relationship with a video carrier is modulated with a multiplex signal, combined with a video carrier modulated with a video signal such as a letterbox system, and transmitted. Quadrature modulation method, (b) Modulates a quadrature carrier having a quadrature phase relationship with a video carrier with a multiplexed signal,
The letter box method and the orthogonal modulation method are used together, such as the letter box method, which is a quadrature modulation method in which the mask part multiplexed signal is combined with the video carrier modulated with the video signal multiplexed and transmitted in the upper and lower mask parts. In that case, attention is paid to the fact that crosstalk occurs between the video signal and the multiplex signal of the letterbox system or the like, and the following effects are obtained.

Utilizing the fact that the modulation degree of the video signal is low in the upper and lower mask portions in the letter box method or the intermediate method, stable horizontal synchronizing signals and clock signals are reproduced, and carrier waves are reproduced for synchronous detection. And the like can be stably performed, so that there is an effect that it is possible to configure a transmission signal reproducing apparatus that is less influenced by a ghost and a video signal.

[Brief description of drawings]

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

2 is a block diagram showing a specific example of a signal reproduction circuit 117 in FIG.

3 is a block diagram showing a specific example of a signal reproducing circuit 117 in FIG.

FIG. 4 is a simulated view of a letterbox screen.

FIG. 5 is a block diagram of a transmission signal reproducing apparatus showing an embodiment of the present invention.

6 is a block diagram showing a specific example of a synchronization detection circuit 501 in FIG.

7 is a block diagram showing a specific example of a synchronization detection circuit 501 in FIG.

FIG. 8 is a block diagram of a transmission signal reproducing device according to an embodiment of the present invention.

FIG. 9 is a block diagram of a transmission signal reproducing device according to an embodiment of the present invention.

FIG. 10 is a block diagram of a transmission signal reproducing device showing an embodiment of the present invention.

11 is a block diagram showing a specific example of carrier recovery circuit 1002 in FIG.

12 is a block diagram showing a specific example of carrier recovery circuit 1002 in FIG.

FIG. 13 is a block diagram of a transmission signal reproducing device according to an embodiment of the present invention.

FIG. 14 is a block diagram showing a specific example of carrier recovery circuit 1301 in FIG.

FIG. 15 is a block diagram showing a specific example of carrier recovery circuit 1301 in FIG.

FIG. 16 is a block diagram of a transmission signal reproducing device showing an embodiment of the present invention.

FIG. 17 is a block diagram showing a specific example of carrier recovery circuit 1602 in FIG.

18 is a block diagram showing a specific example of carrier recovery circuit 1602 in FIG.

[Explanation of symbols]

113 ... Signal processing circuit, 115 ... Sync detection circuit, 116 ... Mask portion detection circuit, 117 ... Signal reproduction circuit, 201 ... Burst extraction circuit, 202 ... Phase comparison circuit, 203 ... switch circuit, 204 ... LPF, 205 ... LPF, 206 ... switch circuit, 207 ... VCO, 208 ... Divider circuit, 301 ... S / H, 501 ... Sync detection circuit, 601, a sync separation circuit, 602 ... Phase comparison circuit, 603 ... a switch circuit, 604 ... LPF, 605 ... LPF, 606 ... Switch circuit, 607 ... VCO, 701 ... S / H, 801 ... Signal processing circuit, 901 ... Signal processing circuit, 1001 ... Multiplication circuit, 1002 ... Carrier wave reproducing circuit, 1103 ... Switch circuit, 1104 ... LPF, 1105 ... LPF, 1106 ... Switch circuit, 1107 ... VCO, 1201 ... S / H, 1301 ... Carrier wave reproducing circuit, 1401 ... Phase comparison circuit, 1602 ... Carrier wave reproducing circuit, 1702 ... Phase comparison circuit, 1703 ... switch circuit, 1704 ... LPF, 1705 ... LPF, 1706 ... switch circuit, 1707 ... VCO, 1708 ... π / 2 phase shift circuit, 1801 ... S / H.

Claims (9)

[Claims] 1. A video carrier in which a vestigial sideband amplitude is modulated by a video signal and a carrier modulated by a signal to be multiplexed in an orthogonal relationship with the video carrier (hereinafter referred to as a multiplexed signal) are synthesized. A video signal demodulation circuit for demodulating the video signal from the received transmission signal to obtain a reproduced video signal in a transmission signal reproducing device for reproducing the video signal and the multiplexed signal from the multiplex-transmitted transmission signal, A synchronization detection circuit that detects a synchronization signal such as a horizontal synchronization signal or a vertical synchronization signal from the reproduction video signal, and a control signal generation circuit that generates a control signal for extracting a certain scanning period of the reproduction video signal from the synchronization signal. And a timing signal from a video multiplex signal such as a color subcarrier signal of the reproduced video signal, which is different between the scanning period and the period other than the scanning period obtained from the control signal. And a signal generation circuit for generating a signal. 2. A video carrier in which the vestigial sideband amplitude is modulated with a video signal and a carrier modulated with a signal to be multiplexed in the orthogonal relationship with the video carrier (hereinafter referred to as a multiplexed signal) are synthesized. A video signal demodulation circuit for demodulating the video signal from the received transmission signal to obtain a reproduced video signal in a transmission signal reproducing device for reproducing the video signal and the multiplexed signal from the multiplex-transmitted transmission signal, A synchronization detection circuit that detects a synchronization signal such as a horizontal synchronization signal or a vertical synchronization signal by using a method different from the scanning period obtained from a control signal from the reproduction video signal and other than the scanning period, and the synchronization signal from the synchronization signal. And a control signal generation circuit for generating the control signal for extracting a certain scanning period of a reproduction video signal. 3. A video carrier in which the vestigial sideband amplitude is modulated by a video signal and a carrier modulated by a signal to be multiplexed in an orthogonal relationship with the video carrier (hereinafter referred to as a multiplexed signal) are synthesized. A video signal demodulation circuit for demodulating the video signal from the received transmission signal to obtain a reproduced video signal in a transmission signal reproducing device for reproducing the video signal and the multiplexed signal from the multiplex-transmitted transmission signal, A synchronization detection circuit that detects a synchronization signal such as a horizontal synchronization signal or a vertical synchronization signal from the reproduction video signal, and a control signal generation circuit that generates a control signal for extracting a certain scanning period of the reproduction video signal from the synchronization signal. A multiplying circuit used for performing synchronous detection on the received transmission signal; and a scanning period obtained from the control signal for performing synchronous detection on the received transmission signal, Serial using different methods other than the scanning period, the transmission signal reproducing apparatus characterized in that a, a carrier recovery circuit for reproducing a multiplexed signal carrier from said multiplication circuit output. 4. A video carrier in which the vestigial sideband amplitude is modulated with a video signal and a carrier modulated with a signal to be multiplexed in the orthogonal relationship with the video carrier (hereinafter referred to as a multiplexed signal) are combined. A video signal demodulation circuit for demodulating the video signal from the received transmission signal to obtain a reproduced video signal in a transmission signal reproducing device for reproducing the video signal and the multiplexed signal from the multiplex-transmitted transmission signal, A synchronization detection circuit that detects a synchronization signal such as a horizontal synchronization signal or a vertical synchronization signal from the reproduction video signal, and a control signal generation circuit that generates a control signal for extracting a certain scanning period of the reproduction video signal from the synchronization signal. A synchronous detection circuit used for performing synchronous detection on the received transmission signal; and a scanning period obtained from the control signal for performing synchronous detection on the received transmission signal. And said using different methods other than the scanning period, the transmission signal reproducing apparatus characterized in that a, a carrier recovery circuit for reproducing a multiplexed signal carrier wave from the transmission signal. 5. The transmission signal reproducing device according to claim 1, 2, 3 or 4, wherein the scanning period is transmitted before and after a video signal in synchronization with a vertical scanning period of the video signal, or on the screen. A transmission signal reproducing device characterized by: a mask portion of a lower image or a blackening period such as a vertical scanning blanking (vertical blanking) of a video signal. 6. The transmission signal reproduction device according to claim 5, wherein the signal generation circuit, the synchronization detection circuit, or the carrier wave reproduction circuit is configured by a phase negative feedback loop, and is faster in the black period and in other periods. Then, a transmission signal reproducing device characterized in that a variable low-pass filter having a slow response characteristic is provided. 7. The transmission signal reproduction device according to claim 5, wherein the signal generation circuit, the synchronization detection circuit, or the carrier wave reproduction circuit comprises a phase negative feedback loop, and the phase negative feedback loop is provided in the dark period. And a switching circuit for closing the phase negative feedback loop during other periods, and a switching circuit for opening the phase negative feedback loop. 8. The transmission signal reproducing apparatus according to claim 1, wherein the reproduction signal is demodulated from the received transmission signal to obtain a reproduction multiplexed signal, and the reproduction multiplexed signal. A signal processing circuit for performing signal processing using the timing signal, and a transmission signal reproducing device. 9. The transmission signal reproducing apparatus according to claim 1, wherein a multiplexed signal demodulating circuit for demodulating the multiplexed signal from the received transmission signal to obtain a reproduced multiplexed signal, and the reproduced video signal. And a signal processing circuit that performs signal processing by using the timing signal for the reproduction multiplexed signal.