JP2675048B2 - Television signal transmitter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal transmission device, and more particularly to a television signal transmission device suitable for so-called EDTV, which is compatible with existing televisions. .

[Conventional technology]

Research and development of EDTV (Extended Definition TV), which is capable of transmitting and receiving high resolution images while preserving compatibility with current televisions, is being pursued in order to achieve high image quality and high definition of current televisions.

In EDTV, significant information necessary for high definition, such as luminance high definition signal and color high definition signal, is superposed on a vacant frequency band that is rarely used by the current television (NTSC). . Related to this is, for example, the method described in JP-A-59-171387. In this system, a luminance signal that is higher than the signal band of the current television is shifted into the current band by frequency shifting and superimposed as a high-definition luminance signal.

[Problems to be solved by the invention]

In order to avoid crosstalk between the luminance signal and color signal of the current television and the luminance high-definition signal which is newly superimposed, the above-mentioned conventional technology uses a video signal obtained from a progressive scanning type imaging system to crosstalk. After performing signal processing such as component removal, the signal is converted into a signal in the current interlaced scanning form. Therefore, there has been a problem that an expensive imaging system such as removal of aliasing distortion is required.

It is an object of the present invention to form an EDTV signal from a composite type NTSC signal obtained from a current television type TV camera, so that an image transmitting apparatus of a television type signal compatible with a current interlaced scanning type TV camera. To provide.

[Means for solving the problem]

The purpose of the above is to extract the luminance signal component of 4.2MHz or more from the composite type NTSC signal obtained from the current TV camera, frequency-convert this, and superimpose it as the luminance high-definition signal to construct the EDTV signal. Is achieved.

[Action]

As shown in Fig. 2 (a), NTSC signals obtained by studio cameras currently used in broadcasting stations are
The color signal C is band-limited according to the current television standard, but the luminance signal is not band-limited. Therefore, the luminance signal has a band up to about 6 MHz. In order to distinguish this type of signal from the NTSC signal of the current television standard (the luminance signal band is 4.2 MHz), it will be referred to as a wideband NTSC signal hereinafter.

In wideband NTSC signal, 4.2 MHz or more luminance signal high-frequency component Y _H is corresponding to the luminance high-definition signal. Therefore, the EDTV signal is constructed by extracting the Y _H component as shown in FIG. 7B, converting it to a frequency band within the current television band by frequency conversion such as frequency shift, and superimposing it. It becomes possible to do.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG. First, the overall operation will be described.

The wide band NTSC signal is extracted by the LPF circuit 1 as a signal component of 4.2 MHz or less as an NTSC signal. On the other hand, the subtraction circuit 2 subtracts the NTSC signal from the wideband NTSC signal,
The luminance high frequency component Y _H is extracted. The Y _H signal is subjected to carrier suppression amplitude modulation by the number of subcarriers μ ₀ in the frequency shift circuit 3, and becomes a luminance high definition signal Y _H ′ which is frequency-shifted within the frequency band of the current television standard.

On the other hand, the motion detection circuit 4 detects motion information by using, for example, the inter-frame difference signal or the inter-frame difference signal of the wideband NTSC signal. And the multiple coefficient k _YH
Is determined in the range from 1 in the case of a still image to 0 in the case of intense motion. The coefficient weighting circuit 5 generates k _YH · Y _H ′ in which the Y _H ′ signal is weighted with the multiple coefficient k _YH . This signal, the NTSC signal, and the μ ₀ phase information necessary for demodulating the luminance high-definition signal on the receiving side are added by the adder circuit 6 to form an EDTV signal.

According to this embodiment, it is possible to generate an EDTV signal with a simple configuration. In this embodiment, some crosstalk may occur between the luminance signal Y _L , the color signal C, and the luminance high-definition signal Y _H ′.

FIG. 3 shows a second embodiment of the present invention. This embodiment is characterized in that the crosstalk component between the Y _L , C and Y _H ′ signals can be reduced.

The wideband NTSC signal is separated in the YC separation circuit 8 into a luminance signal component and a chrominance signal component. In this separation, according to the motion information k detected by the motion detection circuit 4, for example, it is desirable to perform a motion adaptive separation process using correlation between frames in a still image and in a field in a moving image.

The crosstalk component removing circuit 9 removes a crosstalk component between the Y _L , C, and Y _H ′ signals of the EDTV signal. Specifically, the crosstalk component is removed by filtering in the two-dimensional frequency domain of the time frequency and the vertical frequency ν. An example of this characteristic is shown in FIG.

The luminance high frequency component Y _H is subjected to carrier suppression amplitude modulation by the subcarrier μ ₀ in the frequency shift circuit 3 to generate a frequency shifted luminance high definition signal Y _H ′. And
The coefficient weighting circuit 5 weights the multiplex coefficient k _YH .

The adder circuit 6 adds the luminance signal Y _L , the color signal C, the luminance high-definition signal k _YH · Y _H ′, and the μ ₀ phase information, which have been delay-adjusted by the delay circuit 7, to form an EDTV signal.

Next, a detailed description of each block of the above embodiment will be given.

FIG. 5 shows an example of the configuration of the motion detection circuit 4. The wideband NTSC signal is subtracted between the signals delayed by one frame by the 525H delay circuits 10-1 and 10-2 and the subtraction circuits 2-2 and 2-3.
Thus, the difference between the two is taken, and the one-frame difference signal FD ₁ and the two-frame difference signal FD ₂ are extracted. FD ₁ signal is LPF circuit 11
Uses the low-frequency component as motion information. These signals are subjected to absolute value quantization in absolute value quantization circuits 12-1 and 12-2, and a larger one of them is selected in MAX selection circuit 13-1 to become output signal MD. This signal
The MD is smoothed in the spatial smoothing circuit 14-1, for example, between adjacent pixels in the same field. For this smoothing operation, an average value, filtering, etc. are performed. The coefficient determining circuit 15-1 determines the numerical values of the coefficients k and k _YH according to the input signal. That is, when the input signal is 0, it is determined that the region is a still region, the coefficient of k, k _YH is 1, and as the input signal becomes larger, it is determined that the region is a region where the motion is vigorous and k, k _YH is gradually reduced to 0 The coefficient is set so as to approach.

By the way, in the motion detection circuit 4, in order to prevent the motion of detection error of the motion information, it is also possible to use the temporal smoothing together with the spatial smoothing. An example of this structure is shown in FIG. One of the output signals of the spatial smoothing circuit 14-2 is
262H delay circuit 16-1, 1H delay circuit 17-1, MAX selection circuit 13
-3, temporal smoothing is performed by the field back loop composed of the coefficient weighting circuit 5-2. That is, the 262H delay circuit 16-1 and the 1H delay circuit 17-1 respectively obtain the information on the movement of the area corresponding to the upper and lower scanning lines of the previous field by the signals delayed by 262 scanning lines and 1 scanning line, respectively. . The MAX selection circuit 13-3 selects the maximum value, the spatial smoothing circuit 14-3 performs spatial smoothing, and the coefficient weighting circuit 5-2 weights the constant α (α <1). The motion information FDM in the previous field is generated. The larger one of this signal and the motion information MD at the current field is selected by the MAX circuit 13-2 and used as the motion information, whereby temporal smoothing is realized. In the figure, the spatial smoothing circuit 14-3 shown by the dotted line is not always necessary, and may be omitted depending on the case.

In the above configuration example, the motion detection using the 1-frame difference signal and the 2-frame difference signal has been described. However, depending on the case, it is clear that only one of them can be realized.

Now, in the configuration of the embodiment shown in FIG.
It suffices if the motion detection for Y _H is performed. FIG. 7 shows a configuration example of a motion detection circuit suitable for this. In this case, it is extracted by the differential subtraction circuit 2-4 delays the signal from wideband NTSC signal and 525H delay circuit 10-3 correspond to the luminance high frequency components Y _H of this HPF circuit 18-1 The extracted components are extracted. The determination of static / moving is performed according to the magnitude of this component, and the coefficient k _YH is determined. Even with this configuration, S25H
A differential signal between two frames may be used by using a 1050H delay circuit instead of the delay circuit 10-3.

Next, FIG. 8 shows a configuration example of the YC separation circuit 8. With this configuration, YC separation between frames is performed for still images, YC separation between lines is used for intense motion, and YC separation for motion adaptation is performed by mixing the two in the middle of these motions. The operation of the circuit shown in FIG. 8 will be described below.

The wideband NTSC signal and the signal delayed by the 1H delay circuit 17 are respectively -1 // by the coefficient circuits 5-3, 5-4,5-5.
The coefficients of 4,1 / 2, -1 / 4 are weighted. These are addition circuits 6
And the color signal C _{LN in the} YC separation mode between lines is extracted. On the other hand, the subtraction result of the subtraction circuit 2-5 with the 525H delay circuit 10-4 is weighted with a 1/2 coefficient in the coefficient circuit 5-6, and the color signal C _{FM in the} inter-frame YC separation mode is extracted. These components are weighted with the motion information coefficients 1-k, k by the coefficient weighting circuits 5-7, 5-8, and both are added by the adding circuit 6-2, and then predetermined by the BPF circuit 19-1. The components of the color signal band are separated and extracted as the color signal components. Meanwhile, the delay circuit
The component is subtracted from the wideband NTSC signal whose band has been adjusted by 20 by the subtraction circuit 2, and the luminance component is separated and extracted.

Next, an embodiment of the crosstalk component removing circuit 9 will be described with reference to FIG.

The luminance signal and the signal delayed by 2 frames (corresponding to 1050H delay) by the 525H delay circuits 10-5 and 10-6 are
After being added by the adder circuit 6-3, the coefficient weighting circuit 5-9
It is halved, and this signal and 1H delay circuit 17-2 add 1
The signal delayed by the scanning line is added by the adder circuit 6-4, and then the coefficient circuit 5-10 adds a 1/2 coefficient to the HPF circuit 21.
By being extracted as a component corresponding to the luminance high band component at -1, the signal of Y _H of characteristics shown in FIG. 4 (c) is obtained.

On the other hand, 525H delay circuit 10-5, 1H delay circuit 17-3, subtraction circuit 2-7, BPF circuit 19-2, and 1/2 coefficient weighting circuit 5
In the circuit composed of −11 and 5-12, the crosstalk component Y _C is extracted by taking the 1-line differential signal of the 1-frame differential signal. Then, the subtraction circuit 2-8 subtracts the Y _C component from the signal to generate the Y _L signal having the characteristic shown in FIG. 4 (a).

In addition, the signal is subtracted from the signal delayed by the 263H delay circuit 23 by the subtraction circuit 2-9 and corresponding to the 263 scanning line, and a coefficient of 1/2 is weighted (coefficient circuit 5-13) to obtain the fourth signal. The C signal has the characteristics shown in FIG.

Next, an embodiment of the frequency shift unit 3 will be described with reference to FIG. Subcarrier mu _{0 *} subcarrier mu ₀ which is controlled in phase relationship to a desired phase control circuit 26 than is generated. The phase relationship will be described later.

The multiplier 25 multiplies the Y _H signal by the subcarrier μ ₀ to realize carrier suppression amplitude modulation. Then, the BPF circuit 27 extracts the signal component whose frequency is shifted to a desired band and generates a Y _H ′ signal. As an example, FIG. 11 shows a signal spectrum of frequency shift when the subcarrier μ ₀ is 16/7 _SC ( _SC : color subcarrier).

Now, in the frequency shift, the structure of the spectrum of the Y _H ′ signal varies depending on the phase relationship of the subcarrier μ ₀ used. For example, as shown in FIG. 12 (b), when the phase of the subcarrier μ ₀ has a phase inversion relationship for each scanning line and the scanning lines descending for each field have the same phase, , The Y _H ′ signal is “−” as shown in FIG.
They are arranged in the first and third quadrants of the "ν" frequency domain.

On the other hand, as shown in FIG. 13 (b), when the phase of the subcarrier is inverted in units of field, as shown in FIG. 13 (a), Y _H ′ on the ν axis in the “−ν” frequency region. The signal will be placed.

Therefore, the phase control of μ ₀ differs depending on the arrangement method in the “−ν” frequency domain, and by performing the control corresponding to each arrangement, the desired EDTV signal can be obtained. Can be configured.

Further, the frequency of the subcarrier μ ₀ is described as an example of 16/7 _SC , but the frequency is not necessarily limited to this, and the position of the frequency band to be frequency-shifted and the form of frequency shift (parallel shift or inverted shift). It is clear that a frequency suitable for this can be selected according to

〔The invention's effect〕

According to the present invention, it is possible to use an image delay device having a simpler structure than the composite type signal obtained from the current TV camera to obtain the ED.
Since a TV signal can be generated, it is very effective in making the image transmission device economical and cost-effective.

It is obvious that the embodiment of the present invention can be analog, digital, or a mixture of both.

Further, in the present embodiment, an example in which high-definition signals are multiplexed by motion adaptation has been described, but it is also clear that in some cases, it can be realized in the form of constant multiplexing.

Further, in the motion adaptive processing, it is apparent that the present invention can be applied to various control modes from a mode in which a parameter is continuously changed to a binary control of ON and OFF.

Further, in the embodiment of the present invention, it is clear that the form in which the multiplexing of high-definition signals is omitted is also effective as a signal process for removing various interference components as a pre-combing process on the image transmitting side. Is.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of the first embodiment of the present invention, FIG. 2 is a spectrum diagram of a wideband NTSC signal, FIG. 3 is an overall configuration diagram of the second embodiment of the present invention, and FIG. It is a frequency characteristic figure of crosstalk component removal. Further, FIGS. 5 to 7 are all examples of the configuration of the motion detection circuit, FIG. 8 is an example of the configuration of the YC separation circuit, FIG. 9 is an example of the configuration of the crosstalk component removing circuit, and FIG. One configuration example of the shift circuit, FIG. 11, FIG. 12 and FIG. 13 are all characteristic diagrams for explaining the frequency shift operation. 1 ... LPF circuit, 2 ... subtraction circuit, 3 ... frequency shift circuit, 4 ... motion detection circuit, 5 ... coefficient weighting circuit, 6 ...
... Adder circuit, 7 ... Delay circuit, 8 ... YC separation circuit, 9 ...
… Crosstalk component removal circuit, 10 …… 525H delay circuit, 11 …… LPF
Circuit, 12 …… Absolute value quantization circuit, 13 …… MAX selection circuit, 1
4 …… Spatial smoothing circuit, 15 …… Coefficient determination circuit, 16 …… 2
62H delay circuit, 17 …… 1H delay circuit, 18 …… HPF circuit, 19…
… BPF circuit, 20 …… delay circuit, 21 …… HPF circuit, 22 …… delay circuit, 23 …… 263H delay circuit, 24 …… delay circuit, 25 ……
Multiplier, 26 ... Phase control circuit, 27 ... BPF circuit.

Claims (1)

(57) [Claims] 1. A composite wideband NTSC signal in which a chrominance signal is superimposed on a luminance signal obtained from a current television system TV camera is input, and a horizontal frequency is 4.2 MHz.
Separation means for separating the above-mentioned luminance high-frequency component and an NTSC signal of 4.2 MHz or less, and the above-mentioned luminance high-frequency component separated by the separation means
Frequency shift means for outputting a luminance high-definition signal by frequency-shifting in the first and third quadrants of the time-vertical frequency region within the horizontal frequency band of the signal component, and the luminance high-frequency output from the frequency shift means. An image transmitting apparatus for television signals, comprising: an addition means for adding a fine signal to the NTSC signal separated by the separating means to output an EDTV signal.