JPH01229578A - Television signal transmitter - Google Patents

Abstract

PURPOSE:To secure a signal/noise ratio (S/N) at reception and reproduction of additional signals by dividing a TV signal in a vertical space frequency area and shifting the divided signals to the low bands in terms of frequency except the divided signal of the lowest band and transmitting these divided signals via the channels set individually for each divided signal. CONSTITUTION:A TV signal is divided into plural signals in a vertical space frequency area and these divided signals are shifted to the low bands in terms of frequency except the divided signal of the lowest band. These shifted signals are transmitted independently of each other via the different channels. In this case, the total energy of signals has no change but the peak value of the signal of each channel is smaller than that of the original signal. While the disturbance of the signal added to the original color TV signal (NTSC signal) is increased as the increase of the signal peak value as long as the signal total energy has no change. Therefore the disturbance to the NTSC signal can be reduced by transmitting the additional signals with no change of the signal total energy and with reduction of the signal peak value respectively.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention maintains compatibility with an NTSC color television broadcasting system, while also providing a signal different from the original color television signal in this system. The present invention relates to a television signal transmission device suitable for multiplexing a color television signal into an original color television signal and transmitting the multiplexed color television signal.

(Prior Art) The NTSC system, which is one of the color television broadcasting systems, can be said to be an excellent system that is compatible with black and white television broadcasting and has sufficient performance as a color television broadcasting system. This can be seen from the results of implementation in Japan, the United States, and other countries.

Incidentally, over its long history, the image quality of the NTSC system has been significantly improved since its initial implementation as a result of constant efforts on both the transmitting side and the receiving side.

However, the NTSC system has some drawbacks to the recent large-screen displays, and further improvement in image quality is desired.

As a method to improve the image quality of the NTS C system, ID
TV (Uroved Definition T
There is a method called e1evision). This method aims to improve image quality by making full use of the transmitted NTSC color television signal (hereinafter referred to as NTSC signal) on the receiving side. This IDTV could not be implemented under conventional analog technology, but has become possible due to recent advances in digital technology. According to this IDTV, image quality can be significantly improved compared to conventional analog systems.

However, since this IDTV is based on the NTSC system, the upper limit of the image quality that can be improved is limited by the NTSC standard. Here, the upper limit items for the system include (1) screen aspect ratio (2) horizontal resolution of 330 Tv lines.

The aspect ratio of (1) is currently 4:3, but it is known that users prefer ratios such as 5:3 or 6:3 (Broadcasting System published by Japan Broadcasting Publishing Association (Editor) :Japan Broadcasting Corporation)), page 80).

In addition, the high-definition television broadcasting system (High Definition)
16:
9 aspect ratio may be adopted (CCIR
Report 801-2).

Regarding the horizontal resolution (2), in the NTSC system, 4
．． Since the frequency is specified as 2MHz, the limit is 330Tv. On the other hand, considering the number of effective scanning lines (480 lines), a vertical resolution of 450 TV lines is possible even when considering margins such as overscan. Therefore, at this stage, it is desired to improve the horizontal resolution in terms of horizontal and vertical balance.

As an example of a system that improves the above two items and maintains compatibility with current television receivers, for example, Josep
h L, LoCicero A Co11c+ati
ble High-Definition TV
ision 5ysten (SLSC)withCh
rolinance and aspect ratio
o Inpuruvents”5I4PTE Jo
Urnal, Hay 1985. This 5LSC method will be described below.

FIG. 13 shows a spectrum diagram of the 5LSC method.

In FIG. 13, the 4.2 MHz signal to O is a signal for maintaining compatibility with current television receivers. The 4.9 to 10.1 MH2 signal is an additional signal used to expand the aspect ratio and the resolution of one luminance and one chromaticity. Therefore, in this 5LSC system, the signal for one station is transmitted using the band for two channels, and one channel basically transmits a signal similar to the current television broadcast signal, and the other channel transmits a signal that is basically similar to the current television broadcast signal. , and sends additional signals to improve image quality.

According to such a configuration, since the f-addition signal is not included in the channels received by current television receivers, it is considered to be highly compatible with respect to interference. but,
Since each station occupies two channels, it is not efficient, and is expected to be difficult to implement, especially in situations where channel allocation is near the limit, such as in Japan. In addition, when considering intra-station and inter-station transmission, current television broadcasting equipment:
Since it does not have a band of 10 MH2, it is necessary to invest in all new equipment.

It is preferable to aim for transmission within the band of 1 to 1 channel, and if additional signals can be multiplexed around the baseband of 4.2 MHz, current television broadcasting equipment such as video tape recorders and transmitters can be used. It is also possible to achieve compatibility with

As one method of multiplexing additional signals to around 4.2MH2 of the baseband, T.Fukinuki et al.

Extended 0efinition TV Fu
lly CoBableWith EXiStin
(l 5 standard S'' IEEE Tr,onC
onlunication Vol, C0M-32NO
, 8, August 1984.

In the NTSC system, in the case of still images, this method uses luminance detail components (approximately 4 to
This is a 6 MHz signal, and is used to multiplex YH (hereinafter referred to as a luminance high frequency signal). Here, the unused area is
In the vertical-time direction spectrum diagram of FIG. The area of the third quadrant is used. In addition, in the figure, C
is a color difference signal.

By the way, this method is applicable only to still images, and is not applicable to moving images. This is because in the case of videos, the spectrum spreads in the time direction and the original N T
This is because the SC (B signal) and the additional signal (ff degree high frequency signal Y+) overlap, making it impossible to separate both signals on the receiving side.

The brightness high-frequency signal Y is effective for still images, so even if the above method or the additional signal can be transmitted only for still images, the purpose of improving the resolution of still images can be achieved. .

However, when transmitting a signal for expanding the aspect ratio as an additional signal, the additional signal must be sent not only for still images but also for moving images. Therefore, the additional signal is transmitted only for still images. The above-mentioned additional signal multiplexing method that cannot be used cannot be used for transmitting additional signals for expanding the aspect ratio.

In order to solve this problem, it may be possible to limit the motion component of the current NTSC signal, but doing so would likely cause unnatural motion as a side effect, and the existing television reception Compatibility with the machine will be impaired.

In addition, in the case of general natural images, the luminance high-frequency signal Y, has a much lower level than the low-frequency components, so even if it is multiplexed, it will not cause much interference to current television receivers. When transmitting a front-end signal for expanding the aspect ratio, it is necessary to transmit from high-level low-frequency components to high-frequency components, which poses a problem of interference with the current NTSC signal. In order to solve this problem, the transmission level of the additional signal can be lowered, but if this is done, a new essential problem arises in that the signal-to-noise ratio during reception and reproduction is poor.

As mentioned above, in order to multiplex an additional signal to expand the aspect ratio within 4.2MHz of the baseband, it is necessary to: ■ Be able to transmit the additional signal regardless of whether it is a moving image or a still image ■ Current televisions Signal-to-noise ratio (S, ・'N ratio) when receiving and reproducing additional signals with little interference to the receiver
The condition of being able to secure the following conditions must be met. However, at present, no method has been developed that can satisfy these two conditions.

(Problems to be Solved by the Invention) As described above, in the conventional additional signal multiplexing color television transmission device that is compatible with the NTSC color television broadcasting system, one broadcasting channel (6MHz) and Is it possible to transmit color television signals for additional information within the baseband < 4.2 MHz)? This is limited to still images or when transmitting only high-frequency components, but in the case of moving images It was not possible to transmit additional signals when transmitting low frequency components.

This invention was made to specifically address problem (2) among the above-mentioned problems, and it is possible to transmit additional signals that are considered noise in current television receivers without interfering with the original NTSC signal. The purpose of the present invention is to provide a television signal transmission device that can perform the following tasks.

[Structure of the Invention (Means for Solving the Problems) To achieve the above object, the present invention divides a television signal into a plurality of signals in the vertical spatial frequency domain, and divides the television signal into a plurality of signals in the vertical spatial frequency domain, The frequency of the divided signals except for the divided signal at position i is shifted to a lower frequency range, and a plurality of divided signals including the frequency-shifted divided signal are transmitted independently on separate channels.

(Function) In the case of a configuration in which the signal is distributed and transmitted over multiple channels as described above, the total energy of the signal does not change, but the peak value of the signal in each channel is smaller than the peak value of the original signal. Become.

On the other hand, the interference of the additional signal to the original NTSC signal is
If the total energy of the signal is the same, it increases as the peak value of the signal increases.

Therefore, as in the present invention, if the additional signal is transmitted according to a configuration that reduces the peak value without changing the total energy of the signal, it is possible to reduce interference to the N T S C signal. , embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of one embodiment.

Before explaining FIG. 1, an example of an additional signal multiplexing color television signal transmission apparatus to which the present invention is applied will be explained with reference to FIGS. 2 to 8.

In FIG. 2, 11 is an input terminal for color television signals. This signal is a progressive scanning (non-interlaced) signal with an aspect ratio of 16:9, 525 scanning lines, and a frame frequency of 60 Hz.In the drawing, such a non-interlaced signal is expressed as 526/60. do.

This signal consists of a luminance signal represented by Y and color difference signals represented by I and Q.

The signal supplied to the input terminal 11 is sent to the screen division filter 1.
2. This screen division filter 12 divides the input signal into a portion corresponding to the center portion F1 of the screen F in FIG. 3 and a portion corresponding to the side portion F2. Here, the aspect ratio of the screen center portion F1 is set to 4:3.

Screen center portion F1 output from the screen division filter 12
The signal (hereinafter referred to as center signal) is the time expansion port #r
13, and the time axis is expanded by 5/4 times. On the other hand, the signal of the screen side part F2 (hereinafter referred to as side signal)
is expanded four times by the time expansion circuit 14. Figure 4 shows the state of time expansion. Of the effective horizontal scanning period of 53LLs in terms of interspace, 42μs is applied to the screen center portion F1.
is allocated, and 11 μs is allocated to the screen side portion F2. This relationship is <42+11):42X(3/'4)=5:3,
Basically, it supports an aspect ratio of 5:3, but since it involves overscanning in normal television receivers, assuming an overscan of about 6%,
It can also support an aspect ratio of 6:9. Hereinafter, the description will be made using parameters based on the relationship shown in FIG. 4, but if you do not want to allow overscan, you may slightly change the parameters described below.

The center signal is time-expanded by a factor of 5/4, resulting in a band of 0 to 10 MHz. Among the time-expanded center signals, the luminance signal Y is supplied to the luminance high frequency component n circuit 15. This brightness high frequency separation circuit 15 receives input signals from 8 to 8.
It is separated into a luminance high frequency signal YH of 10 MHz and a luminance low frequency signal YL of 0 to 8 MHz) Iz.

The brightness high frequency signal YH has its level suppressed by a level conversion circuit 16, and then is converted by a Y encoder 17 into a signal suitable for multiplexing. On the other hand, low brightness i! The ill signal YL is supplied to the NTSC encoder 19 after undergoing pre-processing in the motion adaptive pre-processing circuit 18 to make it a signal suitable for multiplexing with the luminance high frequency signal YH and the side signal. At this time, the spectrum of the luminance low-frequency component YL is as shown in Fig. 5(a).
It is limited to the area shown in .

Among the center signals output from the time expansion circuit 13, the chromaticity signals I and Q are converted to NTSC by the color difference band limiting filter 20.
After being limited to a band that meets the standard, it is supplied to the NTSC encoder 19. And this NTSC encoder 1
9, along with the luminance low frequency signal YL, N T S C
After being converted into a standard color television signal, it is supplied to the adder circuit 21.

On the other hand, the side signal is time-expanded four times by the time expansion circuit 14, and is made into a signal with a band of 2.2 MHz.

This time-expanded side signal is sent to the time-division color multiplexing circuit 22.
is supplied to This time-division color multiplexing circuit 22 performs line-sequential multiplexing after band-limiting the chromaticity signals I and Qe to 0.25 MHz. Furthermore, by time-division multiplexing this line-sequential multiplexed signal and the luminance signal Y, the signal shown in FIG. 6 is obtained. In this case, the chromaticity signal I.

The amplitude of Q is set to 1.33 (1, 10, 75) times the normal value. This makes it possible to improve the S/N ratio on the receiving side.

The output of the time-division color multiplexing circuit 22 is outputted by the band compression circuit 23 at 525/4 [c] per 1/30 [second] in the vertical direction.
, p, h], and the horizontal direction is compressed to a band of 1 [MHz]. After the level of this compressed output is suppressed by the level conversion circuit 24, the side information encoder 25 outputs the
It is converted into a signal suitable for multiplexing. The spectrum of this converted signal is located in the shaded area in Figures 4(a) and (b), and as shown in Figure 4(a), it is separated from the center signal in the horizontal and vertical spectral regions. in position.

The output of the side information encoder 25 is supplied to the adder circuit 21 and added to the output of the NTSC encoder 19.

This addition output is outputted by the addition circuit 26 to Y, encoder I
It is added to the brightness high-frequency signals Y, , l output from 7.

This addition output becomes a transmission signal.

FIG. 7 shows an example of a specific configuration of the screen division filter 12.

In the figure, the input terminal 1a has an aspect ratio of 16:9.
signal is supplied. This signal is, for example, T=1/
(1,0fsc) (fsc: color subcarrier frequency = 3
．． This is a digital signal discretized at intervals of 579,545 MHz). This signal is supplied to one input terminal of the multiplication circuits 2a, 3a and weighted according to the control signals Xn, Yn supplied to the other input terminals of the multiplication circuits 2a, 3a.

FIG. 8 shows an example of the control signals Xn and Yn, where:
Un is a timing signal indicating the switching timing between the screen center part F1 and the screen side part F2.0 time ti indicates the switching timing from the left screen side part F2 to the screen center part F1, and the time TJ is Screen center part F1
This timing signal Un, which indicates the timing of switching from the screen to the right screen side portion F1, is transmitted separately from the television signal. On the transmitting side, the switching position between the screen center part F2 and the screen side part F2 is set according to the content of the program, and on the receiving side, the screen with an aspect ratio of 16:9 is set according to the timing signal Un sent. Form. The control signals Xn and Yn shown in FIG. 8 have waveforms of squared sine pulses, and are later subjected to time expansion of (5/4)@ and double time expansion due to interlace conversion.
Half gi width is 2 x T x (5/4) x
It is equivalent to the integration of a sine squared pulse of 2" 1 / (2f sc ) = 40 ns, and the maximum frequency f IaX is f11 ax = 1 / (2x half value = 3.58 MHz. Also, in Fig. 8 The control signals Xn and Yn always have a relationship of Xn +yn = 1.

Now, returning to FIG. 1, the configuration and operation of an embodiment of the present invention will be explained.

FIG. 1 is a circuit diagram showing an example of a specific configuration of the band compression circuit 23, level conversion circuit 24, and side information encoder 25 shown in FIG. In addition, in FIG. 1, the band compression circuit 2
3 and the side information encoder 25 are confused, and for convenience of explanation, the level conversion circuit 24 is shown on the side closest to the human power side, but in principle it may be inserted anywhere in the signal processing path in FIG. It is something.

In this FIG. 1, vertical LPF 6g, adder circuit 7g
, horizontal LPF 8g, and vertical frequency shifter 9g constitute the features of this invention.

As shown in Figure 5 above, if signals are transmitted using the area allocated for side information (the shaded area in the figure), the permissible amount of information is 525 vertically per 1/30 second. /4 [c, p, h] x horizontal ICMHz]
This is the amount of information.

The circuit shown in FIG. 1 converts an input signal with a frame frequency of 60H7 into a signal every 17/30 seconds using a frame thinning circuit 5g.

Because frames are thinned out on the sending side in this way,
On the receiving side, reproduction is performed using frame interpolation. In this case, to reduce the unnaturalness of the movement,
The sum of the input signal and the output signal of the frame M extension circuit 1g is taken by the adder circuit 2g, and this is halved by the 1/2 coefficient circuit 3g.
Multiply this to obtain the average output of the signal for two frames. 2D L
PF4g limits the side signal to the spectrum characteristics shown in FIG. 9(a). During transmission, 1/2 information is sent to the line thinning circuit 13d for interlace conversion.

Since it is performed in 20d, the amount of information is 525/4 [
c, p, h]xi [MHz]. The signal obtained in this manner is supplied to a field thinning circuit 5g, where information is thinned out for each frame, resulting in a frame frequency of 30 Hz.

The vertical LPF 6g extracts a signal having the spectrum shown in FIG. 9(b) from the signal having the spectrum shown in FIG. 9(a) output from the field thinning circuit 5g. The adder circuit 7g subtracts its output signal from the input signal of the vertical LPF 6g. By passing this subtracted output through the horizontal LPF 8g, a signal having the spectrum shown in FIG. 9(C) can be obtained. The vertical frequency shifter 9g performs a four-line inversion process on this signal in the vertical direction to obtain a signal having the spectrum shown in FIG. 9(d).

The line thinning circuit Log performs line thinning processing on the output signal of the vertical frequency shifter 9g to obtain a signal whose scanning number d is 262.5 and one horizontal period is time-expanded to 64 μs. The frame frequency of this signal is 3
0H2, the band is 0-0.5MHz. The line distribution circuit 11g divides the input signal and obtains two signals each having 131 scanning lines. 112
g has the number of scanning lines equal to 131 x 2 in one horizontal period by time-compressing the two signals output from the line distribution circuit 11g to 1/2 and time-division multiplexing the compressed output. Get a signal. As a result, the number of scanning lines is 1
31 lines, frame frequency 30H2, band 0 to IMI (Z
signal can be obtained.

The line interpolation filter 13g converts the signal with 131 scanning lines output from the time compression/time division multiplexing circuit 14g into a signal with 525 scanning lines.

At this time, the signal peak value becomes 1/4 and is distributed over 525 scanning lines. This signal is transmitted every 1/30 seconds, 176
Since the output is only for 0 seconds, the line distribution circuit 14
Distribute to odd lines and @number lines with g. Then, after the signal of one line is delayed by one field by the field delay circuit 15g, both signals are selectively selected by the switch circuit 16g according to the field switching signal, so that the number of scanning lines is 262. 5. Obtain a signal with a field frequency of 60 Hz and a band of 0 to IMHz.

The output of the above-mentioned vertical iLPF6g is further determined by the line thinning circuit Fj? Served in 117 g. This line thinning circuit 17g thins out the number of scanning lines of the input signal to 131, and doubles the time. As a result, the number of scanning lines is 131.
In this case, a signal with a frame frequency of 30 Hz and a band of 0 to IMHz can be obtained. This signal is line interpolation filter 1
In 8g, the number of scanning lines is converted to 525, and the peak value is reduced to 1/4. Therefore, no specific signal energy is converted. Thereafter, this signal is converted into a signal having 262.5 scanning lines, a field frequency of 60 Hz, and a band of 0 to IMHz by a line distribution circuit 19g, a field delay circuit 20g, and a switch circuit 21g.

The outputs of the switch circuits 16g and 21g are sent to the multiplier circuit 22g.
, 23g. The frequency of this subcarrier for orthogonal modulation is (6/7) fs c = 195 fH = 3.07 MH2
However, fH is set to the horizontal synchronization frequency, and the phase is inverted for each field. This phase inversion is performed by a phase shift circuit 24g and a switch circuit 25g.

Note that 26g is a phase shift circuit for giving a phase difference of π/2 to the subcarriers supplied to the multiplication circuits 22g and 23g.

The outputs of the multiplier circuits 22g and 23g are supplied to an adder circuit 27g, where the in-phase and quadrature modulation components are summed. A horizontal band pass filter (hereinafter, a band pass filter will be referred to as BPF) removes unnecessary components other than 2 to 4 MHz from this addition output. As a result, a multiplexed signal having a spectrum indicated by diagonal lines in FIG. 4 is obtained. Note that the multiplication circuit 22d
, 23d is a signal having a spectrum shown in a solid line frame in FIG.

FIG. 11 shows another method of band compression.

Vertical 525/4 [c, p, h co, horizontal 1 [MH2] diagonal components are removed as shown in Fig. 18<a), and from this removed output, horizontal 0.5~IM) Iz components are Figure (b)
Minute M as shown in . This separated output is set to the frequency (1/7
) If the carrier wave of fsc is used to return to Meijo in the vertical direction, as shown in Fig. 18 (C), vertical 525/4 [c
, p, hl, horizontally 0, 5 [MH2].

According to such a configuration, there is no need to perform field thinning, and information can be transmitted for each field, thereby eliminating deterioration of motion. However, since oblique components are largely removed, the resolution characteristics deteriorate.

FIG. 12 shows a processing block on the receiving side.

In FIG. 12, 41 is an input terminal to which a received signal is supplied. The received signal supplied to this input terminal 41 is processed by an NTSC decoder 42 into a luminance signal Y and a chromaticity signal 1. It is decoded to Q. In this embodiment, since all the additional signals are included in the luminance region, the luminance signal output of the NTSC decoder 42 includes the 1-increase signal.

Therefore, the luminance signal output of the NTSC decoder 42 is Y
, the decoder 43 and the side information decoder 44, and are decoded. However, in FIG. 20, in order to simplify the explanation, the NTSC decoder 42, Y
l, I decoder 43, and side information decoder 44.
Since the center signal is processed while containing the additional signal, some interference remains in the additional signal. Therefore, in the actual television receiving IAI, the signal separation circuits of the NTSC decoder 42, Y, decoder 43, and side information decoder 44 operate as one, so that unnecessary signals are not input to each decoder 42, 43, and 44. It is composed of

The brightness high frequency signal Y8 of 4 to 5 MHz decoded by the Y decoder 43 is added to the brightness low frequency signal Y1 of the center signal in an adder circuit 45. As a result, a luminance signal Y having a band of 0 to 5 MH2 is obtained.

This 'a degree signal Y is time-compressed by a factor of 415 in the time compression circuit 46, resulting in 6 bands of 0 to 6.25M)12. This time pressure signal a is transmitted to the non-interlace conversion circuit 4.
7, it is converted into a signal with 525 scanning lines, a frame frequency of 60 Hz, and a band of 0 to 13 MH2.

On the other hand, the side signal decoded by the side information decoder 44 is time-compressed by a factor of 1/4 by the time compression circuit 48. As a result, the number of scanning lines is 525, and the frame frequency is 60H2.
, a signal in the band 0 to 8 MH2 is obtained.

This time-compressed side signal and the center signal output from the increment conversion circuit 47 are combined by four screen synthesis circuits and converted into a signal having a large aspect ratio of 16:9. The luminance signal Y and chromaticity signals I, Q outputted from the screen synthesis circuit 49 are converted into R, G by an inverse matrix circuit 50.

It is converted into a snake primary color signal and used for display.

FIG. 13 shows an example of a specific configuration of the side information decoder 44.

In the figure, an additional signal multiplexed composite signal output from a Y/C/M branch circuit 11 and an NTSC decoder 42 is supplied. This Y/C separation circuit 11 converts the input signal into a luminance signal Y
and chromaticity signal C. Of these, the n-degree signal Y is supplied to the additional signal extraction filter 21. This additional signal extraction filter 21 extracts an additional signal included in the input luminance signal Y from the input luminance signal Y. The extracted additional signal is supplied to the orthogonal synchronous demodulation circuit 31 and reproduced into a baseband signal using a subcarrier with a frequency of 6/7 fsc (subcarrier frequency). This demodulated output is converted into a television signal as an additional signal by a band compression decoding circuit 41.

Note that the subcarrier for demodulation is recovered by the subcarrier recovery circuit 51 according to the additional signal multiplex decoded signal.

A specific example of FIG. 13 is shown in FIG. 14.

In FIG. 14, the horizontal HPP 1j extracts components of 2 to 4 MHz from the input signal of the side information decoder 44.

It is now assumed that the signal being input to the horizontal HPF 1j is an n+1 field signal.

In a signal with 525 scanning lines made from signals of two consecutive fields of n, n±1 in one frame, the information of adjacent scanning lines is originally <525/8) [c, p
-h] is expressed by 525 scanning lines, so they have a very high correlation and can be regarded as almost identical signals.

As shown in FIG. 12(b), in the motion area, n
, n+1 fields, only an additional signal whose phase is inverted for each field is multiplexed into one field, and the luminance signal Y is deleted. On the other hand, in the still image area, in addition to the additional signal that is inverted for each field, there is a luminance signal Y representing the same image.

The output signal of HPFlj is sent to field delay circuit 2j, line delay circuits 3j and 4J, and adder circuit 5J.

6j, 1/2 coefficient circuits 7j, and 8j are supplied to upper and lower line averaging circuits. From this upper and lower line average circuit,
In one field of the moving image area, only the additional signal appears, and in the other field, the additional signal with the luminance signal Y superimposed thereon appears. In addition, when the inter-field inversion average is obtained by the addition circuit 9j and the 1/2 coefficient circuit 10J, in the case of a still image,
The luminance signal Y is canceled and only the additional signal is obtained. On the other hand, in the case of a moving image, the luminance signal Y is not canceled out.

Therefore, by selecting the minimum output from the three outputs of the average output of the upper and lower two lines in each field of n and n+1, and the field inversion average output, it is possible to obtain a signal that does not include the luminance signal and consists only of the additional signal. can.

That is, the additional signals included in the three modes of average of the upper and lower two lines in each field of n and n+1 and field inversion average output are all the same, and the f11 signal Y is excluded in at least one mode depending on the image content. There is.

This algorithm is determined by the minimum determination circuit 13j. In this case, the signals of the above three modes are transmitted to the absolute value circuit 1.
After the absolute value of the amplitude 1j'''C'' is taken and the single pulse noise is removed by the median filter 12j, it is supplied to the minimum judgment circuit 13j and subjected to minimum judgment. Note that the minimum determination circuit 13j determines that there are two modes that take the same minimum value.
If there are more than one, it is determined that the mode is still image mode.

The above is a determination algorithm for the three modes, and since this algorithm performs one type of earliest determination, it has the characteristic that malfunctions due to transmission noise and the like are less likely to occur.

In order to separate the additional signal and the luminance signal Y, 525 scanning line signals are required. In the still image mode, this signal can be generated from the signals of fields n and n+1. Therefore, in the still image mode, the switch circuit 14j
, 15j select the signals of fields n and n+1, respectively.

In the n+1 field processing, the above-mentioned addition circuit 6j and 1/2 coefficient circuit 8j are processed from 262.5 scanning line signals.
The average of the upper and lower lines is taken at , and the phase of the average is inverted by an inverting circuit 16j to generate 262.5 scanning line signals. This signal is selected by the switch circuit 15J, and the original 262.5 scanning a signals are selected by the switching circuit 14J, resulting in a total of 525 scanning line signals.Similarly,
In the n-field processing, the addition circuits 5j, 1/
The average of the upper and lower lines is taken by the 2-coefficient circuit 7j, and the phase of this is inverted by the inverting circuit 16j, and the original scanning line signal is sent to the switch circuit 14j.

Select with 15J.

The connection states of the switch circuits N14J and 15j are controlled by the output of the minimum value determination circuit 13j. A valid signal is only for one field period of one frame (two fields, 1/30 seconds). Therefore, this valid signal appears at 1/
Switch circuit 17j, 1 only for 60 seconds, 1 field period
8j is turned on and this valid signal is supplied to the vertical HPF 19j.

Konotaru 1HPF19j is (52 U722 (525/
8) It has a passband of [c, p, h] and extracts the additional signal from the input signal. The extracted additional signal is sent to the multiplication circuit 2
Orthogonal demodulation is performed at 0j and 21J. The horizontal LPF 22J extracts 0 to IMHz components from this demodulated output. As a result, a signal with a number of scanning lines of 262.5 and a frame frequency of 30H2 is obtained. This signal is converted into a signal having 131 scanning lines by a line thinning circuit 23j. Horizontal L
The vertical spectrum of the signal output from PF22J is 5
Since it is limited to the 25/8 rc, p, and h3 bands, information is preserved even if it is converted to a signal with 131 scanning lines by line thinning.

The signal shown in FIG. 16(d) is transmitted by time-division multiplexing two signals with 131 scanning lines, so the time-open division circuit 24j and the time expansion circuit 25j have the original 41 scanning lines. After returning to two signals with 131 lines, the line superimposing circuit 26J converts them into signals with 262.5 scanning lines.

The spectrum of this signal is shown in FIG. 16(d).

After this, this signal is scanned by the line interpolation circuit 27j! Converting to 525 I-numbered signals Next, if this signal is shifted by (525/8) [c, p, h] by the vertical frequency shifter 28j, a signal with the spectrum shown in FIG. 14(c) is obtained. It will be done.

On the other hand, the signal on the multiplication circuit 21J side has 131 scanning lines and has a spectrum as shown in 1/416 figure (b). This signal is converted into a signal with 525 scanning lines by the line interpolation circuit 29J, and then added to the output of the vertical frequency shifter 28J by the addition circuit 30j. As a result, the adder circuit 30j outputs a signal having the spectrum shown in FIG. 16(a). However, this signal is 1/
Since this is a signal that appears once every 3° seconds, a frame interpolation signal is created by frame delay circuits 31J and 32j, an adder circuit 33J, and a 1/2 coefficient circuit 33 with a delay amount of 1/60 seconds, and this and the frame delay circuit The output of the scanning line t is selectively selected every 1/60 seconds by the switch circuit 35J.
&525 lines, a frame frequency of 60) 1z signal is obtained.

By the way, as shown in FIG. 23, the frame interpolation signal is simply an average of the signals of the previous and subsequent frames, and therefore has an element that causes unnatural motion. Therefore, the motion detection circuit 36j detects the amount of motion of the image, and uses the detection output to control the high frequency component of the frame interpolation signal. That is, when there is movement, the unnaturalness of the movement is eliminated by suppressing the high frequency components of the frame interpolation signal.

Note that the high-frequency component of the field interpolation signal output from the 1/2 coefficient circuit 34J is extracted by the horizontal LPF 37J to which this frame interpolation signal is supplied and the addition circuit 38j that performs subtraction processing on the input/output signal of this horizontal LPF 37j. The amplitude of this high frequency component is controlled by the multiplication circuit 39J according to the motion detection output. This control output is added to the low frequency component output from the horizontal LPF 37j in the adder circuit 40j.

The output of the switch circuit 35J is a level conversion circuit 41 having characteristics opposite to those of the level conversion circuit 24 on the transmitting side shown in FIG.
It is converted to the original signal at j. This signal is sent to color decoder 4
2J, the signal is decoded into a luminance signal Y and chromaticity signals I and Q.

FIG. 24 shows an example of a specific configuration of the color decoder 42J.

Here, the number of scanning lines is 525, and the frame frequency is 60Hz.
Since we are considering the signal of chromaticity signal 1. Continuous chromaticity signals I and Q are obtained by expanding Q by 8 times in time expansion circuit 1, and switching the input and output of 2H delay circuit 2 to switch circuit 3 every 2 lines using 4k. It looks like this.

According to this embodiment described in detail above, interference of side signals with respect to the center signal can be reduced.

This means that the side signal with the spectral distribution shown in FIG.
F8gf! - is used to divide the signal into two signals having the spectral distributions shown in FIG. 9(b) and (C), and the high frequency side signal shown in FIG. 9(c) is transmitted to the vertical frequency shifter 9g to
), this is because the frequency is shifted to a lower frequency range, and the shifted output and the signal shown in FIG. 9(b) are transmitted independently through separate channels.

In other words, in the case of a configuration in which side signals are distributed and transmitted over multiple channels, the total energy of the side signals does not change, but the peak value of the side signal in each channel becomes smaller than the peak value of the original side signal. .

On the other hand, if the total energy of the side signals is the same, the interference of the side signals with respect to the center signal increases as the peak value of the side signals increases.

Therefore, as in this embodiment, if the side signals are transmitted according to a configuration that reduces the peak value without changing the total energy of the side signals, interference with the center signal can be reduced.

Although one embodiment of the present invention has been described above in detail, it goes without saying that the present invention is not limited to this embodiment.

For example, in the previous embodiment, the number of divisions of the additional signal is two, but it may be three or more.

[Effects of the Invention] As described above, according to the present invention, an additional signal can be transmitted without interfering with the current NTSC signal.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, and FIG.
The figure is a circuit diagram showing the configuration of an additional signal multiplexing color television signal transmission apparatus to which the present invention is applied, FIGS. 3 to 6 are diagrams for explaining the operation of FIG. 1, and FIG. FIG. 2 is a circuit diagram showing an example of a specific configuration of the screen division filter, FIG. 8 is a diagram for explaining the operation of FIG. 7, and FIGS. 9 and 10 are for explaining the operation of FIG. 1. 11 is a diagram for explaining another band compression method, FIG. 12 is a circuit diagram showing the configuration of an additional signal multiplexing television signal transmission device, and FIGS. 13 and 14 are respectively FIG. 2 is a diagram for explaining different examples of conventional transmission methods. 23...Band compression circuit, 1g...Frame delay circuit, 2g, 7g, 27. g...addition circuit, 3g...1
7/2 coefficient circuit, 4g...2-dimensional LPF, 5g...
Frame thinning circuit, 6g... Vertical LPF, 8g...
Horizontal LPF, 9g...Vertical frequency shifter, Log, 1
7g...Line thinning circuit, l1g...Line distribution circuit, 12g...1/2 time/compression multiplex circuit, 13g
, 18g... line interpolation circuit, 14g, 19g...
Line distribution circuit, 15g, 20g...Field delay circuit, 16g, 21g, 25g...Switch circuit, 2
2g. 23g...multiplier circuit, 24g, 26g...phase shift circuit, 28g...horizontal BPF. Figure 3 Figure 4 Heel 41! S-1 Figure 6 Yn Figure 7 (c) (d) (): Inter L-Mata Matata Zero Box Figure 9

Claims (1)

[Claims] Signal dividing means for dividing a television signal into a plurality of parts in a vertical spatial frequency domain, and dividing the plurality of divided signals outputted from the signal dividing means, excluding the divided signal located in the lowest frequency range. a frequency shifting means for shifting the frequency of the signal to a lower frequency range; and a transmission means for transmitting the plurality of divided signals including the divided signals whose frequency has been shifted by the frequency shifting means through channels individually set for each divided signal. A television signal transmission device comprising: