JP2590881B2 - Waveform distortion detection method and receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Use) The present invention is used in the field of handling television video signals, and specifically, a waveform distortion that can be used in a ghost canceller, a waveform equalizer, a ghost measuring device, and the like. It relates to the detection method.

(Prior Art) The present invention relates to a reference signal used in a waveform distortion removing apparatus and the like. Since the most typical waveform distortion is a ghost generated in a television signal transmission system, the following is described. The explanation is described in relation to the ghost canceller. Since the same concept can be applied to the waveform equalizer, a general description of the waveform distortion removal method is given.

FIG. 3 is a configuration diagram of a ghost canceller generally used. A conventional waveform distortion detection method will be described with reference to FIG. The ghost canceller can be roughly classified into three parts, a filter unit 1, a reference signal extraction circuit 2, and a weight control circuit 3, by function.

The filter unit 1 comprises a cascade-connected delay circuit with taps and a transversal filter for weighting and synthesizing each tap to form a non-recursive type or a cyclic type, but is generally composed of a mixed type. The characteristics of the input line
Expressing the transfer function H () of the output line l ₂ with respect to l ₁ , Here, T = unit delay time of the tap delay circuit, an, bm = weight value, and = frequency. With this H (), it is possible to correct the frequency characteristic distortion caused by the waveform distortion. The weight control circuit 3 controls the weight values an and bm at this time, and the reference signal extraction circuit 2 extracts information for weighting from the video signal.

Pulses with a width as narrow as possible are suitable for ghost detection.In the past, a signal obtained by differentiating the leading edge of the vertical synchronization signal was used. Some waveforms are being used. One of them is a signal a shown in FIG. 4 (a), which is a signal called a random pulse train, and a signal having a constant amplitude and a random pulse width is superimposed in one horizontal scanning period. It is an example. By the way (pseudo)
An example of a random pulse (signal) is a waveform having a constant amplitude and a random pulse width and pulse cycle.

When the signal a shown in FIG. 4 (a) is added to the line l ₁ of FIG. 3, if the waveform distortion of the ghost or the like is not present, the signal a is directly taken l ₂ of the output line. Then the signal line l ₂ is added to the reference signal extraction circuit 2. Here, first, a flat portion of the horizontal period signal of the signal a is clamped, and then a portion of the random pulse train is averaged to extract a DC component thereof, and the DC component is used as a reference potential from the random pulse train by a comparator or the like. create an ideal rectangular pulse train S _0. On the other hand, DC
Withdrawn portion of the pulse train (signal b shown in FIG. 4 (b)), performs correlation calculation between the rectangular pulse train S _0. By this cross-correlation calculation, the waveform of the signal b is changed as shown in FIG.
Is converted into a pulse signal such as the signal c shown in FIG. FIG. 5 is a diagram showing an example of the characteristics of this pulse signal. This pulse signal contains a frequency band component of a video signal up to 4.2 MHz. The pulse signal as a reference signal, for detecting the waveform distortion in the time interval of width T ₀ including the same. 4th
The signal d shown in FIG. 6D is one example, and a ghost having a peak value a (<1) (provided that the peak value of the reference signal is 1.0) is detected at a position shifted by time τ _0. This is an example. This information is transferred to the weight control circuit 3, the weight position and the amount of weight are calculated, and the values of the weight constants an and bm in the above equation (1) are corrected and set.

Thus, the waveform conversion in the reference signal extraction circuit 2
The distortion detection, the calculation and correction of the weight value of the weight control circuit 3, and the filtering process represented by the above equation (1) are repeated every time the waveform of the signal a which is present periodically is detected, and the ghost is gradually reduced. And so on to reduce the waveform distortion.

Since the weighting control circuit 3 performs a correlation operation and the like, it generally includes a part of the function of the reference signal extraction circuit 2 and is mainly configured by a CPU and the like, and is often processed by software.
If there is a problem in processing time or the like, a numerical processor or hardware may be used in addition.

The random pulse train in FIG. 4 (a) is arranged at a constant period, for example, every frame, and the arrangement of the random pulse train changes every time.

(Problems to be Solved by the Invention) The problem with the conventional waveform distortion detection method described with reference to FIGS. 3 to 5 is the processing of a random pulse train for DC (direct current) and its use. It is in. That is, in general, low-frequency distortion such as sag cannot be avoided in a video signal processing system, and a clamp circuit provided as a countermeasure is also provided with a few μm such that a ghost or the like affects a horizontal synchronization signal.
If the delay time is s, the sag may not be completely absorbed. The condition is further worsened because the waveform is usually clamped softly so as not to leave scratches on the waveform. Also, if ghosts are mixed in, the AGC operation is considerably deteriorated, so that it works to promote sag. Accordingly, it is generally determined that the potential of the DC component of the random pulse train as shown in FIG. 4 (a) has a certain slope, and the detection of the DC potential by averaging as described in the description of the conventional example. and conversion to the random pulse train extraction and its ideal rectangular pulse train S _0, such as shown in FIG. 4 (b) by setting the comparison reference potential to the comparator was forced become incomplete.

Therefore, the reference signal portion d including the reference signal c and the waveform distortion such as ghost as shown in FIGS. 4C and 4D includes unnecessary information other than the originally necessary information. The operation of reducing and removing the waveform distortion must be imperfect, and in the worst case, the operation of the filter unit 1 may diverge.

(Means for Solving the Problems) In order to solve the problems described above, the present invention provides a method for detecting a waveform distortion by using all frequency components of a video signal frequency band during a first horizontal scanning period of a video signal. Superimposing a first pseudo-random pulse signal sequence included on the video signal;
And a second pseudo-random pulse signal sequence having a polarity opposite to that of the first pseudo-random pulse signal sequence is superimposed on the video signal in a second horizontal scanning period separated by an even number of horizontal scanning periods from the horizontal scanning period. Signal forming means for transmitting a signal,
In the video signal supplied from the signal forming means, the first
And a signal extracting means for calculating a signal in the second horizontal scanning period to remove a horizontal synchronizing signal and a burst signal, and for extracting an extracted pseudo-random pulse signal train obtained by canceling a DC component. did.

(Embodiment) The waveform distortion detection system according to the present invention has, for example, the following configuration. That is, during the first horizontal scanning period of the video signal, a first pseudo-random pulse signal sequence including all the frequencies of the video signal frequency band is superimposed on the video signal, and an even number of pseudo-random pulse signal trains are output from the first horizontal scanning period. Signal forming means for transmitting a video signal for superimposing a second pseudo-random pulse signal sequence having a polarity opposite to that of the first pseudo-random pulse signal sequence on the video signal during a second horizontal scanning period separated by the horizontal scanning period (For example, having the configuration shown in FIG. 1, the adder 4, the low-pass filters 5, 6 and the switch circuit 7) and the first and the second signals in the video signal supplied from the signal forming means. Signal extracting means (2mH delay circuit 8, subtractor 9) for calculating the signal of the second horizontal scanning period, removing the horizontal synchronizing signal and the burst signal, and extracting the extracted pseudo-random pulse signal sequence obtained by canceling the DC component. , Switch circuit 10) The extracted pseudo-random pulse signal train in the signal forming means obtained by comparing, calculating and low-pass filtering the signals in the first and second horizontal scanning periods in the video signal supplied from the signal forming means. Signal reproducing means (adder 12, comparator 13, low-pass filter 14) for reproducing a reproduced pseudo-random pulse signal train substantially equivalent to
And a correlation operation between the extracted pseudo-random pulse signal sequence extracted by the signal extraction unit and the reproduced pseudo-random pulse signal sequence reproduced by the signal reproduction unit, and addition and averaging processing, thereby calculating all frequencies of the video signal frequency band. Reference signal extracting means (correlator 1) for extracting a reference signal including a band
1, an averaging circuit 15) and a waveform distortion detecting means (weighting detecting circuit 3) for detecting waveform distortion of a video signal simultaneously detected by the reference signal extracting means with reference to the waveform of the reference signal. This is a waveform distortion detection method characterized by the following.

FIG. 1 is a block diagram of one embodiment of a video signal transmitting side of a waveform distortion detection system according to the present invention, FIG. 2 is a block diagram of one embodiment of a receiving side of the present invention, and FIGS. 6 (a) to 6 (i). 3 is a waveform diagram for explaining the operation of the configuration shown in FIGS. 1 and 2. FIG. The same components as those described above are denoted by the same reference numerals, and description thereof will be omitted.
First, the waveform transmitting side will be described with reference to FIGS.

FIG. 6 (a) shows exactly the same waveform as the signal a shown in FIG. 4 (a), and a first random pulse train having a constant amplitude and a random pulse width during one horizontal scanning period in the video signal. It is the figure which showed typically the example inserted. In the figure, the symbols above and below the burst signal indicate the relative phase polarity of the chrominance subcarrier, whereas the symbol 180 ° indicates that the polarity is inverted. .

FIG. 6 (b) is 2mH from the position of the waveform shown in FIG. 6 (a).
(Where m is an integer other than 0 and H is a horizontal scanning period), ie, the first horizontal scanning period shown in FIG.
FIG. 9 is a diagram showing that a second random pulse train in which the polarity of the random pulse train of FIG. Applied above the random pulse train Symbol in FIG. Represents that the polarity of the random pulse train is inverted. The other conditions such as the amplitude and the insertion position are exactly the same. Another characteristic of the waveform shown in FIG. 6 (b) is that the amplitude and polarity of the burst signal are exactly the same as in FIG. 6 (a) from the relative positional relationship with FIG. 6 (a). Of course, the waveform of the horizontal synchronizing signal has the same shape.

The signal waveform shown in FIG. 6A is represented by S (t), and FIG.
Is represented by S (t−2 mH).

FIG. 1 shows an example of a specific method of forming these two signals. Blanking level to the line l ₃ in the figure, i.e., the video signal having the scanning period of no signal is applied. Line l ₄ has a first random pulse train (including DC component, polarity Is added. The line l ₅ second random
Pulse train (including DC, polarity Is added. Added to the line l ₄ and l signal ₅ is low-pass filter, each with appropriate roll-off characteristics as shown in FIG. 5 (LPF) 5, 6, respectively line l ₆ and l ₇
And is added to the switch circuit 7. Line l ₆ when the switch circuit 7 which produces the waveform of FIG. 6 with respect to line l ₈ (a), and when producing the waveform of FIG. 6 (b) connects the line l _7, the other horizontal scanning period In the case of, operation is performed so that no signal is sent.

The adder 4 adds synthesized signal line l ₃ and the line l _8. Thus, the line ₁₉ is obtained from the waveforms shown in FIGS. 6 (a) and 6 (b). In addition, since the operation of detecting and removing a waveform distortion such as a ghost cannot be completed by a single waveform detection, the sixth embodiment is not applicable.
Since the waveforms shown in FIGS. 7A and 7B are often inserted in a vertical blanking period or the like by utilizing the properties of a video signal, the waveforms are repeatedly transmitted at a fixed period, for example, every one frame period. become. Of course, the pulse arrangement of the random pulse, that is, the randomness, changes every period.

What has been described above is the processing on the video signal transmitting side, for example, the broadcasting station side.

Next, the waveform receiving side will be described with reference to FIGS. As an example of the waveform distortion removing apparatus (ghost canceller) on the receiving side, the system configuration is the same as that of FIG. 3 used in the description of the conventional example, but the configuration of the reference signal extracting circuit 2 is different from the conventional example. FIG. 2 is a block diagram of an embodiment of the reference signal extracting circuit 2 embodying the present invention.

In the figure, the input line of the line l ₂ video signal shown in Figure No. 6 (a) (or FIG. (B) is added.
This signal is applied to a 2mH delay circuit 8, a subtractor 9 and an adder 12 for providing a delay of an even number H (2mH, m is an integer not including 0, and H is a horizontal scanning period). The output signal of the delay circuit 8 S (t), and when the signal on line l ₂ and the S (t-2mH), the waveform of each of the video signal corresponding to the view the 6 (a) and (b) .

The subtractor 9 converts the waveform of S (t) in FIG.
The waveform of S (t−2mH) in FIG. The obtained waveform R (t) is represented by R (t) = [S (t) −S (t−2 mH)] / 2 (2), but as shown in FIG. In this case, the waveform of the random pulse train shown in FIG. The horizontal synchronizing signal and the burst signal are canceled out because they have the same polarity and amplitude in FIGS. Low-frequency distortion such as sag that exists in each horizontal cycle is also canceled and disappears, and only the superimposed random pulse train is extracted as it is.

As described above, the detection range of the ghost, that is, the waveform distortion is expanded by the amount of the horizontal synchronization signal and the burst signal being offset, and the random pulse train from which the DC component is removed including the low-frequency distortion such as sag is obtained. Is a feature of the present invention.

The switch circuit 10 functions to extract a signal from the subtractor 9, that is, a signal having a time width necessary for detecting waveform distortion from the waveform shown in FIG. 6C. Extractable time width T ₁
Is considerably wider than the conventional one (the time width shown in FIGS. 4A to 4D), which is the effect of the present invention.

Functions adder 12, which adds averaging the output S of the delay circuit 8 (t) (FIG. 6 (a)) and a line l ₂ of the signal (S (t-2mH) (FIG. 6 (b)) In the equation, the output C (t) is represented by C (t) = [S (t) + S (t−2 mH)] / 2 (3), and FIG. As shown in d), the horizontal sync signal and the burst signal remain unchanged, and the section where the random pulse train is present becomes the setup pulse representing the DC component. Used as a reference potential source.

A comparator 13, in the period T ₂ the setup pulse signal shown in FIG. 6 (d) C (t) is present, compared to its set-up level, the delay circuit 8
It determines whether the potential of the random pulse of the signal S (t) is large or small, and reproduces a rectangular pulse train having a rectangular waveform equivalent to that on the transmitting side. This comparator
The output of 13 is applied to the next low pass filter (LPF) 14. The low-pass filter 14 has substantially the same characteristics (FIG. 5) as the low-pass filters (LPFs) 5 and 6 in FIG. 1, and plays a role of reproducing a random pulse train substantially equal to the transmitting side. I have. FIG. 6 (e) shows the output waveform R ₀ (t).

The output signals of the switch circuit 10 and the low-pass filter 14 are R
(T) and R ₀ (t), the correlator 11 calculates R (t)
A cross-correlation function x (t) of R ₀ (t) is calculated. If you write this as an expression, Here, t is expressed as lag time, and T ₁ is expressed as a random pulse train extraction time width. Actually, it can be composed of a delay circuit, a multiplier, an adder, and some additional circuits. Some of them are commercially available, and their realization is easy. Note that delay time correction for time adjustment for correcting a time delay or the like occurring in processing is omitted for convenience of explanation. The same applies to other descriptions.

The cross-correlation function x (t) given by the above equation (4) is a narrow pulse d (t) (reference signal) determined by the bit rate of the random pulse train and the characteristics of the added low-pass filter.
And R · (t) and R ₀ (t) are random
Residual noise component n caused by including only pulse train
X (t) = d (t) + n (t) (5) where d (t) is a reference signal, and n (t) is residual noise. The output of this correlator 11 is
Added to fifteen.

The averaging circuit 15 calculates the noise component n in the above equation (5).
Utilizing the property of x (t) that periodically arrives at (t),
By averaging, it works to reduce and suppress. The circuit can be realized by an adder, a memory, and some additional circuits.

The output of the averaging circuit 15 thus obtained is as described in (5) above.
The following equation, in which n (t) is omitted in the equation, is represented by y (t) = d (t) (6). FIG. 6 (f) schematically shows this. In the figure, the reference signal d (t) the time width T ₁ of the section extending around a is can be used as a detectable range of the waveform distortion, i.e. a ghost. Since d (t) is set to a narrow pulse that sufficiently contains the frequency component of the frequency band of the video signal (up to 4.2 MHz), it can be effectively used for detecting waveform distortion and ghost. it can. FIG. 6 (f) does not include a ghost (waveform distortion), but the following describes a case where a ghost exists.

As an example, consider an example in which an in-phase ghost having a delay time τ ₀ and an amplitude ratio (amplitude ratio of a ghost to a reference signal) a (<1) is added to a video signal, R (t)
Is a waveform in which the original random pulse train and the ghost random pulse train are superimposed as shown in FIG. 6 (g).
R ₀ (t) has the same waveform as FIG. 6 (e) without ghost as shown in FIG. 6 (h). The absence of ghost in R ₀ (t) is due to the effect of the setup pulse and the comparator 13 in FIG. 6D, which is one of the features of the present invention. The output signal y (t) thus obtained is given by the following equation: y (t) = d (t) + u (t) (7) where u (t) is a ghost of d (t). It contains a ghost component d (t) and is represented as shown in FIG. 6 (i). This waveform y
Sampling a reference signal of a time width T ₁ from (t), the delay time tau ₀ ghost u (t) with respect to a reference signal d _(t), it is possible to detect the amplitude ratio a (<1) or the like. Generally, the waveform of the ghost u (t) includes all information necessary for the ghost canceller, such as the delay time and the amplitude / phase. As described above, the fact that the ghost information can be detected in a wide time zone (T ₁ ) as compared with the conventional time width T ₀ leads to an improvement in the processing capacity of the ghost canceller, which is industrially effective. A beneficial feature is that it has the present invention.

Thus, the accurately extracted reference signal and the information on the waveform distortion such as a ghost are stored in the weight control circuit 3 shown in FIG.
Is calculated, the required weighting value is calculated, and the weighting value of the filter unit 1 (an, bm in the above equation (1)) is corrected and set.

The ghost reduction processing can be sequentially performed using y (t) of the above-described equation (7) detected at a fixed period, for example, for each frame. The removal performance is further improved as compared with the conventional example.

Since the functions of the correlator 11 and the averaging circuit 15 in FIG. 2 do not always need to be processed in real time, the third function which can be constituted by a CPU, a numerical processor, or the like.
It is also possible to transfer the function to the weighting control circuit 3 in the figure and perform the processing by software.

Further, in the above embodiment, two signal trains of the first pseudo random pulse signal train and the second pseudo random pulse train having the opposite polarity are superimposed. The second signal having the same amplitude and opposite polarity as the signal 1
May be superimposed.

(Effects of the Invention) As described above, the waveform distortion detection method and the receiving device according to the present invention have the following effects.

(1) The waveform distortion detection method and the receiving apparatus according to the present invention are:
On the video signal transmitting side, a first signal (first pseudo random pulse signal train) and a second signal (second pseudo random pulse signal train) having the same amplitude and opposite polarity as the first signal. Are superimposed on the video signals separated by an even number H from each other, so that the processing system on the receiving side can perform a stable and reliable processing operation by relatively easy means.

(2) In the method for detecting waveform distortion according to the first aspect and the receiving apparatus according to the fifth aspect, the reference signal is obtained by canceling the horizontal synchronization signal and the color burst signal. The time width for (1) is greatly extended (20 μs or more) compared with the conventional art, and the waveform distortion detection ability can be improved.

(3) The method for detecting waveform distortion according to the second aspect and the receiving apparatus according to the sixth aspect perform arithmetic processing between video signals on which random pulse trains of opposite polarities are superimposed, thereby reducing sag or the like. Random with frequency distortion component removed
Since the pulse train (pulse train including waveform distortion information) can be extracted and the horizontal synchronization signal and the color burst signal are canceled out, the time width for detecting the waveform distortion such as ghost is greatly expanded (more than 20 μs) compared to the conventional art. Waveform distortion detection ability can be improved.

(4) A method for detecting waveform distortion according to claim 3 and a receiving apparatus according to claim 7, wherein the signal reproducing means reproduces a reproduced pseudo random pulse signal train substantially equivalent to the pseudo random pulse signal train on the transmitting side. By adding
In addition to the effect of (3), the original random pulse train from which the waveform distortion component has been removed can be extracted.

(5) The method for detecting waveform distortion according to claim 4 and the receiving apparatus according to claim 8, further comprising: a reference signal extracting means for extracting a reference signal; and a video image simultaneously detected by the reference signal extracting means. By adding a waveform distortion detecting means for detecting the waveform distortion of the signal based on the waveform of the reference signal, the original random pulse train from which the waveform distortion component described in the above (4) is removed and the above-mentioned (3) By performing the cross-correlation calculation process with the random pulse train including the waveform distortion information and the averaging process, a narrow pulse (that is, a reference signal) sufficiently including the frequency band component of the video signal is obtained.
And its waveform distortion (for example, ghost) can be detected with high accuracy, and furthermore, since the reference signal portion is extracted from the random pulse train by correlation operation, the SN (signal-to-noise ratio) with respect to noise and the like included in the video signal can be improved. .

(6) In connection with the good SN described in (5) above,
The influence of the jitter fluctuation of the clock signal (sampling pulse) which is likely to occur when the video signal is sampled and processed, and the horizontal sync signal and the burst signal which may be generated due to the imperfect cancellation of the signal slightly disappear, APL
In the series of correlation operations described in the above (5), even a slight variation can be rounded down and reduced to an almost negligible order, thereby greatly improving the waveform distortion detection capability of a ghost canceller, a waveform distortion removing device, or the like. it can. Of course, it is also possible to apply to ghost measurement and the like.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a video signal transmitting side of a waveform distortion detection system according to the present invention, FIG. 2 is a partial block diagram of an embodiment of a receiving side of the present invention, and FIG. 4 and 5 are explanatory diagrams of the operation of the ghost canceller shown in FIG. 3, and FIG. 6 is a waveform diagram for explaining the operation of FIGS. 1 and 2. 1 ... Filter section, 2 ... Reference signal extraction circuit, 3 ... Weight detection circuit, 4,12 ... Adder, 5,6,14 ... Low-pass filter (LPF), 7,10 ... Switch Circuit, 8 2 mH delay circuit, 9 ... subtractor, 11 ... correlator, 13 ... comparator, 15 ... averaging circuit, R (t) ... first signal sequence, R ₀ (t )... Second signal sequence.

Claims (8)

(57) [Claims] In a waveform distortion detection method used for removing waveform distortion of a television video signal, a first side different from a color burst signal for detecting a waveform distortion in a first horizontal scanning period of a video signal on a transmission side. And a second signal having the same amplitude and opposite polarity as the first signal during the second horizontal scanning period separated from the first horizontal scanning period by an even number of horizontal scanning periods. By superimposing and transmitting the signals, the receiving side removes the horizontal synchronizing signal and the color burst signal by an operation for calculating the difference between the signals in the first and second horizontal scanning periods, and sets a reference signal for obtaining the waveform distortion. A waveform distortion detection method characterized by extracting and detecting waveform distortion in a transmission system based on the reference signal. 2. A waveform distortion detection system used for removing waveform distortion of a television video signal, comprising: a transmitting side which includes all frequency components of a video signal frequency band during a first horizontal scanning period of the video signal. Are superimposed on each other, and during a second horizontal scanning period separated by an even number of horizontal scanning periods from the first horizontal scanning period, a second pseudo-random pulse signal sequence having a polarity opposite to that of the first pseudo-random pulse signal sequence is obtained.
A signal forming means for transmitting a video signal on which the pseudo random pulse signal train is superimposed; and a receiving side for performing a calculation for obtaining a difference between the signals in the first and second horizontal scanning periods in the video signal to perform horizontal synchronization. A signal extracting means for removing a signal and a color burst signal and canceling out a DC component to extract an extracted pseudo-random pulse signal sequence. 3. A waveform distortion detection system used for removing waveform distortion of a television video signal, wherein a transmitting side includes all frequency components of a video signal frequency band in a first horizontal scanning period of the video signal. Are superimposed on each other, and during a second horizontal scanning period separated by an even number of horizontal scanning periods from the first horizontal scanning period, a second pseudo-random pulse signal sequence having a polarity opposite to that of the first pseudo-random pulse signal sequence is obtained.
A signal forming means for transmitting a video signal on which the pseudo random pulse signal train is superimposed; and a receiving side for performing a calculation for obtaining a difference between the signals in the first and second horizontal scanning periods in the video signal to perform horizontal synchronization. Signal extracting means for removing a signal and a color burst signal and canceling out a DC component to extract an extracted pseudo-random pulse signal train; a signal in the first horizontal scanning period and a signal in the second horizontal scanning period in a video signal; To calculate the sum with the signal of
The calculation result is used as a DC reference value, and this DC reference value is compared with the signal in the first or second horizontal scanning period, and the amplitude component of the first pseudo random pulse signal train in the signal forming means is obtained. And the amplitude component of the same waveform as
Signal distortion means for reducing and filtering the amplitude component and reproducing a reproduced pseudo random pulse signal train substantially equivalent to the first pseudo random pulse signal train in the signal forming means. method. 4. A waveform distortion detection system used for removing waveform distortion of a television video signal, wherein the transmitting side includes a first horizontal scanning period of the video signal that includes all frequency components of the video signal frequency band. Are superimposed on each other, and during a second horizontal scanning period separated by an even number of horizontal scanning periods from the first horizontal scanning period, a second pseudo-random pulse signal sequence having a polarity opposite to that of the first pseudo-random pulse signal sequence is obtained.
A signal forming means for transmitting a video signal on which the pseudo random pulse signal train is superimposed; and a receiving side for performing a calculation for obtaining a difference between the signals in the first and second horizontal scanning periods in the video signal to perform horizontal synchronization. Signal extracting means for removing a signal and a color burst signal and canceling out a DC component to extract an extracted pseudo-random pulse signal train; a signal in the first horizontal scanning period and a signal in the second horizontal scanning period in a video signal; To calculate the sum with the signal of
The calculation result is used as a DC reference value, and this DC reference value is compared with the signal in the first or second horizontal scanning period, and the amplitude component of the first pseudo random pulse signal train in the signal forming means is obtained. And the amplitude component of the same waveform as
A signal reproducing means for reducing and filtering the amplitude component and reproducing a reproduced pseudo random pulse signal train substantially equivalent to the first pseudo random pulse signal train in the signal forming means; and the extracting means extracted by the signal extracting means. Reference signal extraction for extracting a reference signal covering the entire frequency band of the video signal frequency band by correlation calculation and addition averaging of the pseudo random pulse signal train and the reproduced pseudo random pulse signal train reproduced by the signal reproducing means. Means for detecting waveform distortion of a video signal simultaneously detected by the reference signal extracting means with reference to the waveform of the reference signal. 5. A receiving apparatus for a television video signal, wherein a first signal different from a color burst signal for detecting waveform distortion is superimposed during a first horizontal scanning period of the video signal, and In a second horizontal scanning period separated from the horizontal scanning period by an even number of horizontal scanning periods, a transmission television image signal in which a second signal having the same amplitude and opposite polarity as the first signal is superimposed is supplied. The horizontal synchronization signal and the color burst signal are removed by a calculation for obtaining a difference between the signals in the first and second horizontal scanning periods, and a reference signal for obtaining a waveform distortion is extracted. A receiving device provided with detecting means for detecting waveform distortion in a transmission system. 6. A television video signal receiving apparatus, comprising: a first pseudo-random pulse signal sequence including all frequency components of a video signal frequency band during a first horizontal scanning period of a video signal; A transmission television in which a second pseudo random pulse signal sequence having a polarity opposite to that of the first pseudo random pulse signal sequence is superimposed in a second horizontal scanning period at an even number of horizontal scanning period intervals from one horizontal scanning period. An image signal is supplied, an operation for obtaining a difference between the signals in the first and second horizontal scanning periods in the image signal is performed, a horizontal synchronization signal and a color burst signal are removed, and a DC component is canceled out and extracted. A receiving device comprising signal extracting means for extracting a pseudo random pulse signal sequence. 7. A television video signal receiving apparatus, comprising: a first pseudo random pulse signal sequence including all frequency components of a video signal frequency band during a first horizontal scanning period of a video signal; A transmission television in which a second pseudo random pulse signal sequence having a polarity opposite to that of the first pseudo random pulse signal sequence is superimposed in a second horizontal scanning period at an even number of horizontal scanning period intervals from one horizontal scanning period. An image signal is supplied, an operation for obtaining a difference between the signals in the first and second horizontal scanning periods in the image signal is performed, a horizontal synchronization signal and a color burst signal are removed, and a DC component is canceled out and extracted. Signal extracting means for extracting a pseudo-random pulse signal sequence; and performing an operation for obtaining a sum of the signal of the first horizontal scanning period and the signal of the second horizontal scanning period in the video signal. The result is defined as a DC reference value, and this DC reference value is compared with the signal in the first or second horizontal scanning period, and is compared with the amplitude component of the first pseudo random pulse signal train in the signal forming means. Signal reproducing means for obtaining an amplitude component of the same waveform, reducing and filtering the amplitude component, and reproducing a reproduced pseudo random pulse signal train substantially equivalent to the first pseudo random pulse signal train in the signal forming means. A receiving device, characterized in that: 8. A television video signal receiving apparatus, comprising: a first pseudo-random pulse signal sequence including all frequency components of a video signal frequency band during a first horizontal scanning period of a video signal; A transmission television in which a second pseudo random pulse signal sequence having a polarity opposite to that of the first pseudo random pulse signal sequence is superimposed in a second horizontal scanning period at an even number of horizontal scanning period intervals from one horizontal scanning period. An image signal is supplied, an operation for obtaining a difference between the signals in the first and second horizontal scanning periods in the image signal is performed, a horizontal synchronization signal and a color burst signal are removed, and a DC component is canceled out and extracted. Signal extracting means for extracting a pseudo-random pulse signal sequence; and performing an operation for obtaining a sum of the signal of the first horizontal scanning period and the signal of the second horizontal scanning period in the video signal. The result is defined as a DC reference value, and this DC reference value is compared with the signal in the first or second horizontal scanning period, and is compared with the amplitude component of the first pseudo random pulse signal train in the signal forming means. A signal reproducing means for obtaining an amplitude component having the same waveform, reducing and filtering the amplitude component, and reproducing a reproduced pseudo random pulse signal train substantially equivalent to the first pseudo random pulse signal train in the signal forming means; The correlation between the extracted pseudo-random pulse signal train extracted by the extracting means and the reproduced pseudo-random pulse signal train reproduced by the signal reproducing means includes all the frequency bands of the video signal frequency band by an addition averaging process. A reference signal extracting means for extracting a reference signal; and a waveform distortion of the video signal detected simultaneously by the reference signal extracting means, based on a waveform of the reference signal. And a waveform distortion detecting means for detecting the distortion.