JPH05207435A - Transmission signal reproduction device - Google Patents

Abstract

PURPOSE:To eliminate a crosstalk stably in a two-dimension transversal filter with high quality by eliminating a delay error caused between a demodulated video signal inputted to the two-dimension transversal filter and a demodulated multiplex signal to the utmost. CONSTITUTION:Filters 111, 112 are formed on the same board as a SAW filter 113 and characteristics such as a group delay characteristic and an absolute delay time are selected equally. The tendency of occurrence of an error in various characteristics with respect to an environmental change such as a temperature change is identical, as a result, since the occurrence of a relative error such as the group delay characteristic and the absolute delay time between the filters 111 and 112 is prevented, the occurrence of malfunction in the crosstalk elimination is prevented, resulting that a demodulation signal with high quality is obtained.

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 transmission signal reproducing apparatus effective for receiving a transmission signal which is transmitted by multiplexing another signal on a current television broadcast signal.

[0002]

2. Description of the Related Art As a method of multiplexing another signal on a television signal, a quadrature modulation in which a carrier having a quadrature relationship with a video carrier is modulated with other information and is combined with a video carrier modulated with the video signal for transmission. The scheme is known.

[0003] However, this system is based on the 1988 National Television Society National Convention Lectures published by the Institute of Television Engineers of Japan, pp. 329 to 330, page 15-8, "Examination of waveform equalization in EDTV system with carrier quadrature modulation". As discussed in (1), a signal having different information (hereinafter referred to as a signal to be multiplexed) due to the imbalance of the characteristics of the filters on the transmitting side and the receiving side, the deviation of the detection of the receiver, and the ghost disturbance. Crosstalk may occur between the video signal and the multiplex signal). It is necessary to use a waveform equalization technique to remove this crosstalk.

An example of removing this crosstalk is described in Japanese Patent Application Laid-Open No. 63-109676.
Known reference signals are inserted into the video signal and the multiplexed signal in advance, and the two orthogonal signals are received on the receiving side.
Two demodulated signals separated and demodulated by synchronous detection with the axis detection phase are passed through two delay lines with taps,
It uses a two-dimensional transversal filter that synthesizes each delayed signal with an appropriate weight determined using the received reference signal.

[0005]

However, in the above-mentioned prior art, since the system for demodulating the video signal and the system for demodulating the multiplex signal are independent, they are input to the two-dimensional transversal filter and demodulated. A large delay error may occur between the video signal and the demodulated multiplexed signal, and this delay error has not been sufficiently considered.

If there is a delay error, the two-dimensional transversal filter cannot operate normally, and not only the above-mentioned crosstalk cannot be removed but also the removal operation diverges to cause a large interference.

An object of the present invention is to provide a quadrature modulation system in which a carrier wave having an orthogonal relationship with a video carrier wave is modulated with other information, and the modulated carrier wave is combined with a video carrier wave modulated with a video signal for transmission.
Transmission signal regeneration to remove the delay error generated between the demodulated video signal and the demodulated multiplex signal input to the two-dimensional transversal filter as much as possible and to remove crosstalk with the two-dimensional transversal filter stably and with good quality To provide a device.

[0008]

In order to achieve the above object, in the present invention, a video carrier whose vestigial sideband amplitude is modulated by a video signal and an orthogonal relationship with the video carrier are multiplexed. In a transmission signal reproducing device for synthesizing a carrier wave modulated by a power signal (hereinafter referred to as a multiplex signal) and reproducing the video signal and the multiplex signal from the multiplex-transmitted transmission signal, First filter means having a pass band characteristic having a symmetrical amplitude characteristic with respect to a frequency and extracting and outputting a signal within the pass band from the transmission signal; and a Nyquist characteristic having a frequency of the video carrier as a center. And a second filter means having a pass band characteristic equivalent to that of the first filter means and extracting a signal within the pass band from the transmission signal and outputting the signal.
A composite filter means having two systems of filter means,
First frequency conversion means for frequency-converting and outputting the signal from the first filter means, and first demodulation means for synchronously detecting and outputting the signal from the first frequency conversion means,
Second frequency conversion means for frequency-converting and outputting the signal from the second filter means; second demodulation means for synchronously detecting and outputting the signal from the second frequency conversion means; This is achieved by providing a two-dimensional transversal filter which receives the signal from the first demodulation means and the signal from the second demodulation means as input, weights them with a desired weight, and synthesizes and outputs.

[0009]

In the present invention, the first in the composite filter means
Since the side means wave of the video signal is obtained symmetrically in the filter means, the high-quality multiplexed signal with less crosstalk from the video signal is obtained at the output of the first demodulation means, and the second filter in the composite filter means is obtained. Since the means has the Nyquist characteristic, the sidebands of the multiplex signal can be obtained symmetrically, so that a high-quality video signal with little crosstalk from the multiplex signal can be obtained at the output of the second demodulation detection means. Since the composite filter means has the first filter means and the second filter means, the group delay characteristic of the first filter means and the group delay characteristic of the second filter means, and the temperature characteristic of the group delay characteristic. It becomes easy to make the same etc.

Further, in the two-dimensional transversal filter, even when there is multipath propagation so-called ghost, an inverse signal can be produced and canceled by the output of the first demodulating means and the output of the second demodulating means. Therefore, a high-quality multiplexed signal can be obtained, and the frequency conversion means can lower the intermediate frequency for demodulating the multiplex-transmitted signal from the intermediate frequency for amplitude modulation and demodulation. An error due to time and the like can be reduced, and a stable demodulated signal can be obtained.

As described above, according to the present invention, it is possible to improve the quality of these signals and to perform stable demodulation operation.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a transmission signal reproducing apparatus as a first embodiment of the present invention. In FIG. 1, 101 is an antenna, 102 is a high frequency amplifier circuit, 103 is a frequency conversion circuit, 104 is a local oscillation circuit, 105 is a channel selection control circuit, 106 is a Nyquist filter, 107 is a video signal detection circuit, and 108 is an audio FM detection circuit. Circuit, 109 is an audio signal output terminal, 110 is a video signal output terminal, 111, 112
Is a filter, 113 is a SAW filter composed of filters 111 and 112, 114 and 115 are frequency conversion circuits, 116 is an oscillation circuit, 117 is a multiplication circuit, 118 is a voltage-controlled oscillation circuit, and 119 is a low-pass filter (hereinafter ,
LPF) 120 is a multiplication circuit, 121 is a carrier recovery circuit, 122 is a two-dimensional transversal filter, 1
Reference numeral 23 is a multiple signal output terminal.

The television signal input from the antenna 1 is amplified by the high frequency amplifier circuit 102, and the frequency conversion circuit 10
In step 3, it is converted into an intermediate frequency for demodulation. The tuning of the television signal is performed by controlling the frequency of the local oscillation circuit 104 added to the frequency conversion circuit 103 by the tuning control circuit 105. From the frequency-converted intermediate frequency signal, a video signal band signal is obtained by a Nyquist filter 106 that has a Nyquist characteristic centered on the video signal carrier and extracts the video signal band, and the video signal detection circuit 107 amplifies and detects the video signal. A video signal is obtained at the signal output terminal 110.

On the other hand, the audio signal band is amplified and detected by the audio FM detection circuit 108 from the video signal detection circuit 107 to obtain an audio signal at the audio signal output terminal 109.

In addition to the above, in order to demodulate multiple signals,
The output of the frequency conversion circuit 103 is extracted by a filter 111 having an amplitude characteristic symmetrical with respect to the video signal carrier, and the frequency conversion circuit 114 converts the multiplexed signal band into an intermediate frequency lower than the intermediate frequency for demodulating the video signal. .. Thereafter, the multiplication circuit 117 performs synchronous detection using the reproduced carrier wave obtained from the voltage controlled oscillator circuit 118 to obtain a multiplexed signal, and the LPF 119 extracts the phase error signal and extracts the phase error signal from the voltage controlled oscillator circuit 118. A negative carrier is fed back to obtain a reproduced carrier wave.

Further, the output of the frequency conversion circuit 103 is a filter 1 having a Nyquist characteristic centered on a video signal carrier.
12, the multiplexed signal band is extracted, the frequency conversion circuit 115 sets the intermediate frequency to a frequency lower than the intermediate frequency for demodulating the video signal, and the carrier recovery circuit 121 uses the voltage controlled oscillator circuit 1.
Carrier waves having a phase difference of 18 and 90 degrees are reproduced, and synchronous detection is performed by the multiplication circuit 120 to obtain a video signal within the multiple signal band.

The multiplexed signal obtained by the multiplication circuit 117 and the video signal obtained by the multiplication circuit 120 are input to the two-dimensional transversal filter 122 to remove crosstalk and obtain a multiplexed signal at the multiplexed signal output terminal 123. ..

The filters 111 and 112 are SAWs.
The filters 113 are formed on the same substrate and have the same characteristics such as group delay characteristics and absolute delay time.

FIG. 2 is a characteristic diagram showing the characteristics of the main filter used in the present invention and the frequency spectrum of the main signal before and after the filter input / output.

Reference numeral 201 denotes a transmission spectrum of a video signal, 20
2 is the transmission spectrum of the multiplex signal, 203 is the filter characteristic of the multiplex signal band having the Nyquist characteristic around the video signal carrier, 204 is the filter characteristic of the multiplex signal band having the symmetrical amplitude characteristic around the image signal carrier, Reference numeral 205 is a filter characteristic of a video signal band having an amplitude characteristic symmetrical with respect to the video signal carrier, 206 is a video signal spectrum when demodulating a video signal within the multiple signal band, and 207 is demodulating a video signal within the multiple signal band. In the case of a multiplex signal spectrum, 208 is a video signal spectrum in the case of demodulating the multiplex signal, 209 is a multiplex signal spectrum in the case of demodulating the multiplex signal, 210 is a video signal spectrum in the case of demodulating the video signal, 211 is a video signal. The video signal spectrum when demodulated.

FC is a video signal carrier frequency, fQ is a multiple signal band, and fI is a video signal band.

(A) is an explanation path for demodulating the video signal in the multiple signal band of FIG. 1, (b) is an explanation path for demodulating the multiple signal of FIG. 1, and (c) is the video signal of FIG. It is an explanation route when demodulating.

The output spectra of the frequency conversion circuit 103 are spectra 201 and 202, and from this, the spectra 206 and 207 are obtained by using the filter 112 having the filter characteristic 203. On the other hand, by using the filter 111 having the filter characteristic 204, the spectra 208, 2
To get 09. In addition, the Nyquist filter 106 having the filter characteristic 205 is used for the spectrum 21 of the video signal band.
We get 0 and 211.

When demodulating a video signal within the multiple signal band,
Since the filter 112 has the Nyquist characteristic centered on the video signal carrier, it transmits the multiplexed signal having the inverse characteristic centered on the video signal carrier and the symmetrical amplitude characteristic about the video signal carrier. Multiple signal spectrum with 20
7, and since the video signal spectrum 206 and the multiplex signal spectrum 207 have an orthogonal relationship, a video signal without crosstalk from the multiplex signal can be demodulated by synchronous detection.

Similarly, when demodulating a multiplexed signal, the filter 111 has an amplitude characteristic symmetrical with respect to the video signal carrier, so that the video signal spectrum having the symmetrical amplitude characteristic with respect to the video signal carrier. Since the video signal spectrum 208 and the multiplex signal spectrum 209 are orthogonal to each other, the multiplex signal without crosstalk from the video signal can be demodulated by the synchronous detection.

The filters 111 and 112 are SAWs.
Since the filters 113 are formed on the same substrate, errors in various characteristics with respect to environmental changes such as temperature changes have the same tendency to occur, and as a result, the group delay characteristics and absolute delay time between the filters 111 and 112 are increased. It is possible to prevent the occurrence of relative error such as.

After that, the frequency conversion circuit 114 and the frequency conversion circuit 115 can operate the multiplication circuit 117 and the multiplication circuit 120 at an intermediate frequency lower than the intermediate frequency for demodulating the video signal, so that the delay time of the synchronous detection circuit and The error due to the delay time of the signal line can be reduced, and stable detection and demodulation operation becomes possible.

Multiplier circuit 11 for demodulating the multiplexed signal
7. A synchronous detection circuit composed of the voltage control type oscillation circuit 118 and the LPF 119, and a synchronous detection circuit composed of a multiplication circuit 120 and a carrier recovery circuit 121 are used to demodulate the video signal in the multiple signal band. Therefore, regardless of the quadrature phase error between the video signal carrier and the multiplexed signal carrier caused by the delay error generated between the frequency conversion circuit 114 and the frequency conversion circuit 115, the carrier having the optimum phase for each synchronous detection can be reproduced. ..

Further, even if a ghost or the like causes a leak between the multiplex signals output from the multiplying circuit 117 and the video signal within the multiplex signal band output from the multiplying circuit 120, the transmitting side may leak the signals. The leak is detected with the sent reference signal as a reference, and the two-dimensional transversal filter 122 is weighted with these signals as an input, thereby canceling the leak between these signals to obtain a high-quality multiplexed signal. Obtainable.

In this embodiment, the SAW filter 11 described above is used.
3, a frequency conversion circuit 114, a frequency conversion circuit 115, a synchronous detection circuit composed of a multiplication circuit 117, a voltage control type oscillation circuit 118, and an LPF 119 for demodulating a multiplex signal, and a demodulation of a video signal in the multiplex signal band The operation of the synchronous detection circuit including the multiplication circuit 120 and the carrier wave recovery circuit 121 and the operation of the two-dimensional transversal filter 122 have an effect that a stable detection and demodulation operation and a good multiplexed signal can be obtained. For simplicity, the frequency conversion circuits 114 and 115 and the oscillation circuit 116 are omitted,
A configuration in which synchronous detection is performed without frequency conversion to the low frequency band is also possible.

FIG. 3 is a block diagram showing a transmission signal reproducing apparatus as another embodiment of the present invention. In FIG. 3, 3
Reference numeral 01 denotes a variable phase shift circuit, and other elements having the same reference numerals as those in FIG. 1 have the same function.

In the embodiment of FIG. 3, a variable phase shift circuit 301 is provided in place of the voltage control type oscillation circuit 118 of FIG. 1, and the carrier for reproducing the video signal reproduced by the carrier recovery circuit 121 is changed. And the output of the LPF 119 is used as a control signal to variably adjust the phase of this carrier wave.

The carrier used to reproduce the multiplexed signal in the multiplication circuit 117 and the carrier used to reproduce the video signal in the multiplication circuit 120 have the same frequency and different phases by π / 2. The variable phase shift circuit 301 adjusts the carrier wave for the video signal reproduced by the carrier wave reproducing circuit 121 so as to have an optimum phase for reproducing the multiplexed signal.

In the embodiment shown in FIG. 3, since the variable phase shift circuit can be used instead of the local oscillation circuit, there is an effect that a cheap and stable detection demodulation operation and a good multiplexed signal can be obtained.

FIG. 4 is a block diagram showing a transmission signal reproducing apparatus as another embodiment of the present invention. In FIG. 4, 4
01 is a carrier recovery circuit, 402 is a variable phase shift circuit,
In addition, the same reference numerals as those in FIG. 1 indicate the same functions.

In the embodiment of FIG. 4, instead of the carrier wave reproducing circuit 121 of FIG. 1, a carrier wave reproducing circuit 401 having two outputs of a 0 phase carrier wave and a π / 2 phase carrier wave is provided.
Further, a variable phase shift circuit 402 is provided in place of the voltage control type oscillation circuit 118 of FIG. 1, and the carrier wave reproduced by the carrier wave reproduction circuit 401 is input to the variable phase shift circuit 402, so that the LPF 11
Using the output of 9 as a control signal, the phase of this carrier is variably adjusted.

The carrier wave used for reproducing the multiplexed signal in the multiplication circuit 117 and the carrier wave used for reproducing the video signal in the multiplication circuit 120 have the same frequency and different phases by π / 2. The carrier wave reproduction circuit 401 outputs a 0-phase carrier wave for a carrier wave used for reproducing a video signal and a π / 2 phase carrier wave for a carrier wave used for reproducing a multiplex signal, and further outputs a variable shift signal. The phase circuit 402 finely adjusts the carrier wave for the multiplex signal reproduced by the carrier wave reproducing circuit 401 so as to have an optimum phase for reproducing the multiplex signal.

The variable phase shift circuit 402 ideally has a phase change amount of 0, but is between the filter 111 and the filter 112 or between the frequency conversion circuit 114 and the frequency conversion circuit 1.
The phase error between the carrier for reproducing the video signal and the carrier for reproducing the multiplex signal, which is caused by a delay error such as between 15, is absorbed.

In the embodiment of FIG. 4, a variable phase shift circuit can be used in place of the local oscillation circuit, and the phase shift range of the variable phase circuit can be made small. And, there is an effect that a high quality multiplexed signal can be obtained.

FIG. 5 shows an embodiment of the carrier recovery circuit 401 of FIG.

Reference numeral 501 is a transmission signal input terminal, 502 is a multiplication circuit, 503 is a low pass filter (hereinafter abbreviated as LPF), 504 is a voltage control type oscillation circuit, 505 is a π / 2 phase shift circuit, and 506 is 0 phase. Carrier output terminal, 507 is π
It is a carrier output terminal of / 2 phase.

The output signal of the frequency conversion circuit 115 is sent to the multiplication circuit 502 via the transmission signal input terminal 501 and multiplied by the reproduced carrier wave, and the LPF 503 extracts the phase error component. The extracted phase error component is
Used as a control signal for the voltage controlled oscillator circuit 504,
The frequency of the output signal of the voltage controlled oscillator circuit 504 is changed. The output signal of the voltage controlled oscillator circuit 504 is π / 2.
The phase shift circuit 505 receives a phase change of π / 2 and is input to the multiplication circuit 502.

In the embodiment of the carrier recovery circuit 401 shown in FIG. 5, the phase of the carrier component included in the signal input to the transmission signal input terminal 501 and the phase of the output signal of the π / 2 phase shift circuit 505 are π. Since the carrier wave output terminal 506 is locked by being shifted by / 2, a carrier wave of 0 phase is output from the carrier wave output terminal 507 with reference to the phase of the carrier wave component included in the signal input to the transmission signal input terminal 501.
A carrier of π / 2 phase is output.

The embodiment of FIG. 5 can also be used for the carrier recovery circuit 121 of FIG. 1, and in that case, the 0-phase carrier output from the carrier output terminal 506 is used.

FIG. 6 is a block diagram showing a transmission signal reproducing apparatus as another embodiment of the present invention. In FIG. 6, 6
Reference numeral 01 is a phase comparison circuit, 602 is a variable phase shift circuit, and 603 is a π / 2 phase shift circuit. In addition, the same reference numerals as those in FIG. 1 indicate the same functions.

In the embodiment shown in FIG. 6, a phase comparison circuit 601 and a variable phase shift circuit 6 are used instead of the carrier recovery circuit 121 shown in FIG.
02, π / 2 phase shift circuit 603 is provided, the carrier wave for multiplex signal regeneration reproduced by the voltage controlled oscillation circuit 118 is input to the variable phase shift circuit 602, and the output of the phase comparison circuit 601 is used as a control signal. Adjust the carrier phase variably. The variably adjusted carrier wave undergoes a phase change of π / 2 in the π / 2 phase shift circuit 603, and the phase comparison circuit 601 extracts the phase error signal with the carrier wave included in the output of the frequency conversion circuit 115 to perform the variable phase shift. It is used as a control signal for the circuit 602.

The carrier wave used for reproducing the multiplexed signal in the multiplication circuit 117 and the carrier wave used for reproducing the video signal in the multiplication circuit 120 have the same frequency and different phases by π / 2. The variable phase circuit 602 adjusts the carrier wave for the multiplexed signal reproduced by the voltage controlled oscillator circuit 118 to the optimum phase for reproducing the video signal.

In the embodiment of FIG. 6, since the variable phase shift circuit can be used instead of the local oscillation circuit, there is an effect that a cheap and stable detection demodulation operation and a high quality multiplexed signal can be obtained.

FIG. 7 shows an embodiment of the phase comparison circuit 601 shown in FIG.

Reference numeral 701 denotes an input terminal for the reproduced carrier wave, and 7
Reference numeral 02 denotes a phase error signal output terminal, and other reference numerals that are the same as those in FIG. 5 indicate the same functions.

The output signal of the frequency conversion circuit 115 is sent to the multiplication circuit 502 via the transmission signal input terminal 501, and the reproduced carrier wave is multiplied by the carrier wave input from the input terminal 701. The error component is extracted and output from the phase error signal output terminal 702.

In the embodiment of the phase comparison circuit 601 shown in FIG. 6, the phase of the carrier component contained in the signal input to the transmission signal input terminal 501 and the phase of the output signal of the π / 2 phase shift circuit 603 are π. Since the phase shifts by 1/2, the variable phase shift circuit 602 sets 0 as a reference with respect to the phase of the carrier wave component included in the signal input to the transmission signal input terminal 501.
The phase carrier is output.

FIG. 8 is a block diagram showing a transmission signal reproducing apparatus as another embodiment of the present invention. In FIG. 8, 8
01 is a variable phase shift circuit, 802 is a π / 2 phase shift circuit,
In addition, the same reference numerals as those in FIGS. 1 and 6 indicate the same functions.

In the embodiment shown in FIG. 8, a phase comparison circuit 601 and a variable phase shift circuit 8 are provided instead of the carrier recovery circuit 121 shown in FIG.
01, π / 2 phase shift circuit 802 is provided, the carrier for reproducing the multiplex signal reproduced by the voltage controlled oscillation circuit 118 is input to the variable phase shift circuit 801, and the output of the phase comparison circuit 601 is used as a control signal. Adjust the carrier phase variably. The variably adjusted carrier wave is extracted by the phase comparison circuit 601 as a phase error signal with the carrier wave included in the output of the frequency conversion circuit 115 and is used as a control signal for the variable phase shift circuit 801. A carrier wave used for reproducing the multiplexed signal in the multiplication circuit 117,
The carrier waves used for reproducing the video signal in the multiplication circuit 120 have the same frequency but different phases by π / 2. The variable phase circuit 801 uses the π / 2 phase shift circuit 802 to convert the carrier wave for the multiplexed signal reproduced by the voltage controlled oscillator circuit 118 to π /
After the phase is changed by 2, the fine adjustment is performed so that the phase is optimum for reproducing the video signal.

The variable phase shift circuit 801 ideally has a phase change amount of 0, but between the filter 111 and the filter 112 or between the frequency conversion circuit 114 and the frequency conversion circuit 1.
The phase error between the carrier for reproducing the video signal and the carrier for reproducing the multiplex signal, which is caused by a delay error such as between 15, is absorbed.

In the embodiment shown in FIG. 8, a variable phase shift circuit can be used in place of the local oscillation circuit, and the phase shift range of the variable phase circuit can be made small. And, there is an effect that a high quality multiplexed signal can be obtained.

FIG. 9 is a block diagram showing a transmission signal reproducing apparatus as another embodiment of the present invention. In FIG. 9, 9
Reference numeral 01 is a voltage control type oscillation circuit, reference numeral 902 is a local oscillation circuit, and the same reference numerals as those in FIG. 1 indicate the same functions.

The difference from the embodiment of FIG. 1 is that the multiplication circuit 11
In FIG. 7, synchronous detection is performed using a signal obtained from the local oscillation circuit 902 to obtain a multiplexed signal, and a phase error signal is extracted by the LPF 119 and the phase error signal is negatively fed back to the voltage control type oscillation circuit 901. Is. As a result, the voltage-controlled oscillator circuit 901 operates so that the frequency of the carrier wave included in the signal whose frequency is converted by the frequency converter circuit 114 becomes equal to the frequency of the signal obtained from the local oscillator circuit 902, and And a signal obtained from the local oscillation circuit 902 operate so that the phase difference between them becomes π / 2.

According to the embodiment of FIG. 9, since the operating frequencies of the multiplication circuit 117, the multiplication circuit 120, and the carrier recovery circuit 121 can be made constant by the negative feedback, a stable detection and demodulation operation can be performed, and as a result, There is an effect that a high quality multiplexed signal can be obtained.

FIG. 10 is a block diagram showing a transmission signal reproducing apparatus as another embodiment of the present invention. In FIG. 10, reference numeral 1001 denotes a local oscillation circuit, 1002 denotes a π / 2 phase shift circuit, and other elements having the same reference numerals as those in FIGS. 1, 6, and 9 indicate the same functions.

The difference from the embodiments of FIGS. 1 and 9 is that a local oscillator circuit 1001 is used instead of the carrier wave recovery circuit 121 and a signal obtained from the local oscillator circuit 1001 is used.
This is that the multiplication circuit 120 performs synchronous detection to obtain a video signal in a multiple signal band, the phase comparison circuit 601 extracts a phase error signal, and the phase error signal is negatively fed back to the voltage control type oscillation circuit 901. As a result, in the voltage controlled oscillator circuit 901, the frequency of the carrier wave included in the signal frequency-converted by the frequency converter circuit 115 is the local oscillator circuit 100.
1 so as to be equal to the frequency of the signal obtained from 1 and the phase difference between the carrier and the signal obtained from the π / 2 phase shift circuit 1002 is π / 2, that is, the local oscillation circuit 1001. It operates so that it has the same phase as the signal obtained from.

According to the embodiment of FIG. 10, the operating frequencies of the multiplication circuit 117, the voltage control type oscillation circuit 118, the multiplication circuit 120, the phase comparison circuit 601, and the π / 2 phase shift circuit 1002 are fixed by the negative feedback. Therefore, a stable detection and demodulation operation can be performed, and as a result, a good quality multiplexed signal can be obtained.

FIG. 11 is a block diagram showing a transmission signal reproducing apparatus as another embodiment of the present invention. 11, the same reference numerals as those in FIGS. 1, 3, 6, 9, and 10 indicate the same functions.

The embodiment of FIG. 11 is a modification of the embodiment of FIG. 10 to the embodiment of FIG.

According to the embodiment of FIG. 11, the multiplication circuit 11
7, the variable phase shift circuit 301, the multiplication circuit 120, the phase comparison circuit 601, and the π / 2 phase shift circuit 1002 can be made constant in operating frequency, so that stable detection and demodulation operation can be performed, and as a result, a good multiplexed signal can be obtained. There is an effect that can be obtained.

FIG. 12 is a block diagram showing a transmission signal reproducing apparatus as another embodiment of the present invention. 12, the same reference numerals as those in FIGS. 1, 4, 6, 9, and 10 indicate the same functions.

The embodiment of FIG. 12 is a modification of the embodiment of FIG. 10 to the embodiment of FIG.

According to the embodiment of FIG. 12, the multiplication circuit 11
7, the variable phase shift circuit 402, the multiplication circuit 120, the phase comparison circuit 601, and the π / 2 phase shift circuit 1002 can be made constant in operating frequency, so that stable detection and demodulation operation can be performed, and as a result, a high-quality multiplexed signal can be obtained. There is an effect that can be obtained.

FIG. 13 is a block diagram showing a transmission signal reproducing apparatus as another embodiment of the present invention. 13, the same reference numerals as those in FIGS. 1, 6 and 9 indicate the same functions.

The embodiment of FIG. 13 is a modification of the embodiment of FIG. 9 to the embodiment of FIG. According to the embodiment of FIG. 13, the multiplication circuit 117, the multiplication circuit 120, the phase comparison circuit 601, the variable phase shift circuit 602, and the π / 2 phase shift circuit 6 are provided.
Since the operation frequency of 03 can be made constant, stable detection and demodulation operation can be performed, and as a result, there is an effect that a high-quality multiplexed signal can be obtained.

FIG. 14 is a block diagram showing a transmission signal reproducing apparatus as another embodiment of the present invention. 14, the same reference numerals as those in FIGS. 1, 6, 8, and 9 indicate the same functions.

The embodiment of FIG. 14 is a modification of the embodiment of FIG. 8 to the embodiment of FIG. According to the embodiment shown in FIG. 14, the multiplication circuit 117, the multiplication circuit 120, the phase comparison circuit 601, the variable phase shift circuit 801, and the π / 2 phase shift circuit 8 are provided.
Since the operation frequency of 02 can be made constant, stable detection and demodulation operation can be performed, and as a result, there is an effect that a high-quality multiplexed signal can be obtained.

[0073]

According to the present invention, in the first filter means in the composite filter means, the sidebands of the video signal are obtained symmetrically, so that the output of the first demodulation means is free from the crosstalk from the video signal. A small number of good quality multiplexed signals are obtained, and since the second filter means in the composite filter means has the Nyquist characteristic, sideband waves of the multiplexed signals are obtained symmetrically, so that the output of the second demodulation detection means is obtained. Provides a good quality video signal with less crosstalk from the multiplex signal, and since the composite filter means includes the first filter means and the second filter means, the group delay characteristic of the first filter means is obtained. Since it becomes easy to make the group delay characteristics of the second filter means and the temperature characteristics of the group delay characteristics the same, the demodulated video signal input to the two-dimensional transversal filter and the demodulated multiplexed signal are input. It is possible to remove the delay error that occurs between signals as much as possible, and as a result, the crosstalk from the video signal to the multiple signal, or the multiple signal to the video signal, which occurs when multipath propagation so-called ghost exists, etc. When crosstalk is removed by using a two-dimensional transversal filter, it is possible to prevent the occurrence of malfunction of the crosstalk removal operation, and thus it is possible to obtain a high-quality demodulated signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a transmission signal reproducing device as a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing characteristics of a main filter used in the present invention and frequency spectra of main signals before and after filter input / output.

FIG. 3 is a block diagram showing a transmission signal reproducing device as a second embodiment of the present invention.

FIG. 4 is a block diagram showing a transmission signal reproducing device as a third embodiment of the present invention.

FIG. 5 is a block diagram showing an embodiment of a carrier recovery circuit which is a main part of the present invention.

FIG. 6 is a block diagram showing a transmission signal reproducing device as a fourth embodiment of the present invention.

FIG. 7 is a block diagram showing an embodiment of a phase comparison circuit which is a main part of the present invention.

FIG. 8 is a block diagram showing a transmission signal reproducing device as a fifth embodiment of the present invention.

FIG. 9 is a block diagram showing a transmission signal reproducing device as a sixth embodiment of the present invention.

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

FIG. 11 is a block diagram showing a transmission signal reproducing device as an eighth embodiment of the present invention.

FIG. 12 is a block diagram showing a transmission signal reproducing device as a ninth embodiment of the present invention.

FIG. 13 is a block diagram showing a transmission signal reproducing device as a tenth embodiment of the present invention.

FIG. 14 is a block diagram showing a transmission signal reproducing device as an eleventh embodiment of the present invention.

[Explanation of symbols]

 111, 112 ... Filter 113 ... SAW filter 114, 115 ... Frequency conversion circuit 116 ... Oscillation circuit 117, 120 ... Multiplier circuit 118 ... Voltage controlled oscillator circuit 119 ... LPF 121 ... Carrier wave regeneration circuit 122 ... Two-dimensional transversal filter 301 ... Variable phase shift circuit 401 ... Carrier recovery circuit 402 ... Variable phase shift circuit 601 ... Phase comparison circuit 602 ... Variable phase shift circuit 603 ... .pi. / 2 phase shift circuit 801 ... Variable phase shift circuit 802 ... .pi. / 2 phase shift circuit 901 ... Voltage control type oscillation circuit 902 ... Local oscillation circuit 1001 ... Local oscillation circuit 1002 ... π / 2 phase shift circuit

Claims (7)

[Claims] Claim: What is claimed is: 1. A video carrier in which the vestigial sideband amplitude is modulated by a video signal, and a carrier modulated orthogonally with the video carrier and modulated by a signal to be multiplexed (hereinafter referred to as a multiplexed signal) are combined. Then, in the transmission signal reproducing device for reproducing the video signal and the multiplexed signal from the multiplex-transmitted transmission signal, having a pass band characteristic having an amplitude characteristic symmetrical about the frequency of the video carrier, It has a first filter means for extracting a signal in a pass band from a transmission signal and outputting it, and a Nyquist characteristic centered on the frequency of the video carrier, and a pass band characteristic equivalent to that of the first filter means. Then, a composite filter means having a two-system filter means of a second filter means for extracting and outputting a signal within a pass band from the transmission signal, and a signal from the first filter means. Demodulating means for synchronously detecting and outputting the signal, second demodulating means for synchronously detecting and outputting the signal from the second filter means, the signal from the first demodulating means and the second A two-dimensional transversal filter which receives the signal from the demodulating means of (1) as input, adds it with a desired weight, and outputs the synthesized signal. 2. A composite of a video carrier whose vestigial sideband amplitude is modulated with a video signal and a carrier which is orthogonal to the video carrier and modulated with a signal to be multiplexed (hereinafter referred to as a multiplexed signal). Then, in the transmission signal reproducing device for reproducing the video signal and the multiplexed signal from the multiplex-transmitted transmission signal, having a pass band characteristic having an amplitude characteristic symmetrical about the frequency of the video carrier, It has a first filter means for extracting a signal in a pass band from a transmission signal and outputting it, and a Nyquist characteristic centered on the frequency of the video carrier, and a pass band characteristic equivalent to that of the first filter means. Then, a composite filter means having a two-system filter means of a second filter means for extracting and outputting a signal within a pass band from the transmission signal, and a signal from the first filter means. Frequency conversion means for frequency-converting and outputting the signal, first demodulation means for synchronously detecting and outputting the signal from the first frequency conversion means, and frequency conversion for the signal from the second filter means. Second frequency converting means for converting and outputting, second demodulating means for synchronously detecting and outputting the signal from the second frequency converting means, the signal from the first demodulating means and the second A two-dimensional transversal filter which receives a signal from the demodulation means of (1) as an input, adds a desired weight to the signal, and outputs the combined signal. 3. The transmission signal reproducing apparatus according to claim 1, wherein a SAW filter is used as the composite filter means having the first filter means and the second filter means. Transmission signal reproducing device. 4. The transmission signal reproducing apparatus according to claim 1, 2 or 3, wherein the first and second frequency converting means have the same local oscillating means. 5. A composite of a video carrier which is vestigial sideband amplitude modulated by a video signal and a carrier which is orthogonal to the video carrier and is modulated by a signal to be multiplexed (hereinafter referred to as a multiplexed signal). Then, in a transmission signal reproducing device for reproducing the video signal and the multiplexed signal from the multiplex-transmitted transmission signal, carrier reproducing means for reproducing the video carrier or the carrier from the transmission signal, and the carrier reproducing means. From the variable phase shift means and a phase error signal extracted from the transmission signal and used as the control signal of the variable phase shift means. A transmission signal reproducing apparatus comprising: an extracting unit. 6. A composite of a video carrier whose vestigial sideband amplitude is modulated with a video signal and a carrier which is orthogonal to the video carrier and modulated with a signal to be multiplexed (hereinafter referred to as a multiplexed signal). Then, in the transmission signal reproducing device for reproducing the video signal and the multiplexed signal from the multiplex-transmitted transmission signal, the local oscillation means for frequency-converting and outputting the transmission signal, the oscillation frequency being varied by the control signal Frequency conversion means having: a carrier wave reproduction means for reproducing the video carrier wave or the carrier wave from a signal from the frequency conversion means; an oscillating means for outputting a signal having the same frequency as the video carrier wave or the carrier wave; And a phase error extracting means for extracting a phase error signal from the signal from the frequency converting means and using the phase error signal as the control signal of the local oscillating means. Transmission signal reproducing apparatus according to claim and. 7. A composite of a video carrier which is vestigial sideband amplitude modulated by a video signal and a carrier which is orthogonal to the video carrier and modulated by a signal to be multiplexed (hereinafter referred to as a multiplexed signal). Then, in the transmission signal reproducing device for reproducing the video signal and the multiplexed signal from the multiplex-transmitted transmission signal, the transmission signal is frequency-converted and output, and the oscillation frequency is changed by the first control signal. A frequency converting means having a local oscillating means, an oscillating means for outputting a signal having the same frequency as the video carrier or the carrier, extracting a phase error signal from the signal from the oscillating means and the signal from the frequency converting means, A first phase error extracting means for setting the first control signal of the local oscillating means, a variable phase shift means for varying a phase of a signal from the oscillating means by a second control signal; Second phase error extraction means for extracting a phase error signal from the signal from the phase shift means and the signal from the frequency conversion means and using it as the second control signal of the local oscillation means. And a transmission signal reproducing device.