JPH0730866A - Television signal transmitter-receiver - Google Patents

Abstract

PURPOSE:To prevent mis-matching of motion detection between an encoder and a decoder by applying multiplexing signals without motion adaptive processing when a luminance horizontal high frequency component is sent within an existing TV signal band. CONSTITUTION:An LPF 1 and an HPF2 separate a Y component below 4.2MHz and a Y component over 4.2MHz and an output of the HPF 2 is given to a vertical-time LPF3, in which a vertical and time frequency band is limited. Then a modulator 4 shifts the frequency within 4.2MHz and the result is added to an output Y component of the LPF 1 at an adder 5. The signal spectrum for a motion picture is time-limited by the LPF 3 but the signal is not limited for a still picture by the LPF 3 because the band of the signal spectrum of the still picture is narrow and since the signal level differs automatically from both signals, no motion detection is required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal transmitting / receiving apparatus, and more particularly to the current television system 4.2MH.
The present invention relates to an EDTV (Enhanced TV) system television transmitting / receiving apparatus that transmits a horizontal high frequency component of 4.2 MHz or more in the z band.

[0002]

2. Description of the Related Art FIG. 6 shows an example of an encoder (transmitting device) of this type of EDTV television transmission system. The input luminance signal (Y) is a horizontal LPF (low pass filter).
4.2M with 1 and horizontal HPF (high pass filter) 2
It is separated into a signal component within Hz and a signal component above 4.2 MHz. The signal component within 4.2 MHz which is the output of the LPF 1 is used as one input of the direct adder 5.

On the other hand, the output of HPF2 is 4.2 MHz.
The above horizontal high frequency component Hh is modulated by the modulator 4,
The frequency is shifted so that the signal frequency is in the 2-4.2 MHz band. The frequency-shifted modulated signal Hh 'becomes the other input of the adder 5 and is added with the luminance component of the main signal within 4.2 MHz and transmitted.

In this way, high-frequency components of 4.2 MHz or higher are multiplexed by shifting to a frequency within 4.2 MHz and converted. A specific method of this multiplexing is, for example, This is described in detail in Japanese Patent Laid-Open No. 3-46475, "Transmission system of television signal". That is, as shown in FIG. 3, the vertical-time frequency domain (ν-
(f region), the chroma component (C) which is a color modulation signal
The horizontal high frequency component (Hh ') is multiplexed at a position conjugate with.

The position conjugate with the chroma component is called a "blown hole" using the name of the creator, and is shown as a hole in FIG.

In such a high frequency component multiplexing system using the "blowing hole", it is effective for a still image, but during a moving image, a luminance signal and a color signal leak into this hole, and are multiplexed in this hole. Crosstalk with the converted components may occur.

Therefore, as shown in FIG. 7, the motion detection circuit 1
2 is used to detect a moving image, and the horizontal high-frequency component H
Although h is multiplexed, there is a method of performing an adaptive process such that the switch 13 is not used when a moving image is used.

[0008] For example, various characteristics of EDTV encoders using current interlaced scanning camera signals by Hirano et al., Vol. 43, No. 5
(1989), pp 505-512.

[0009]

When the motion adaptive processing shown in FIG. 7 is performed, the receiving side also detects the motion and does not add the horizontal high frequency component Hh to the main luminance signal at the time of moving image. An adaptive process of adding is required for still images.

However, since the signal properties of the transmitting side and the receiving side are not completely the same, there is a case where the motion detection is mismatched during transmission and reception. This mismatch causes deterioration of image quality.

Further, in the simplified encoder shown in FIG. 6, since the transmission side always performs multiplexing, the above-mentioned transmission / reception mismatch does not occur, but the horizontal high frequency component Hh is multiplexed even during a moving image. Therefore, there is a disadvantage that Hh is erroneously demodulated as a color signal.

An object of the present invention is to eliminate a mismatch due to motion detection during transmission and reception by multiplexing a horizontal high frequency component of 4.2 MHz or higher within a band of a current television signal without motion adaptation processing. It is an object of the present invention to provide a television signal transmitting / receiving device capable of performing the above.

[0013]

A television signal transmitting apparatus according to the present invention is a transmitting apparatus for multiplexing a luminance horizontal high frequency signal on a television signal and transmitting the multiplexed signal, wherein the horizontal high frequency signal is extracted from the luminance signal. The high-pass filter means, the low-pass filter means for band-limiting the extracted output in the vertical-time frequency domain, and the band-limited output for 4.2.
It is characterized by including a modulation means for frequency softening in the MHz band and an addition means for adding the modulated output to the luminance component of the main signal.

In the television signal receiving apparatus according to the present invention, the luminance horizontal high frequency signal is multiplexed at a position conjugate with the modulated color signal in the vertical-time frequency domain, and the multiplexed signal and the luminance signal of the main signal are combined. A television receiving device for receiving the added television transmission signal, comprising a separating means for receiving the television transmission signal and separating signals other than the luminance signal of the main signal from the received signal, and the separation output. From the vertical-time frequency domain to extract the luminance horizontal high-frequency signal multiplexed in a position conjugate with the modulated color signal, the demodulation means to demodulate the extracted output to a baseband signal, It is characterized by including motion detecting means for detecting whether the received signal is a moving image or a still image, and means for controlling the addition of the demodulated output to the luminance signal of the main signal according to the detected output.

[0015]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of a transmission apparatus (encoder) according to an embodiment of the present invention, and the same parts as those in FIG. 6.7 are designated by the same reference numerals. In the figure, a luminance (Y) signal extracted from a video signal source such as a camera (not shown) is input to the horizontal LPF 1 and the horizontal HPF 2 and separated and extracted into band components of 4.2 MHz or less and 4.2 MHz or more, respectively. .

The extraction output Hh of the HPF 2 is the vertical-time LP.
Limited by F3. The characteristics of this LPF3 are shown in FIG.
It is shown in (a) and (b). In FIG. 2, A is the amplitude, ν is the vertical frequency (TVL), and f is the time frequency (Hz
). 31 shows a characteristic.

That is, in this LPF 3, the vertical is 24
Bandwidth is limited to 0TVL (TV book) and time frequency is also limited to 7.5Hz or less. The reason why the signal band is limited by the LPF 3 will be described with reference to FIG.

In the case of a still image, the signal spectrum 41 of the image sticks to the ν axis and does not spread to the f axis as shown in FIG. 4 (a). This is because the still image has no signal change in the time direction.
This is because it is regarded as the C component only. Therefore, the signal spectrum 41 is limited only in the vertical direction by the LPF 3.

On the other hand, during a moving image, as shown in FIG. 4 (b), there is a signal change in the time direction and the signal spectrum 41 spreads in the time direction. Therefore, most of the signals in the spectrum will be cut.

Therefore, as the characteristic 31 of the LPF 3, it is necessary to have an extremely narrow band in the time axis direction. Therefore, in this embodiment, it is limited to 7.5 Hz or less. In this case, the LPF 3 is a time-frequency FIR filter,
Although it is realized by a circuit configuration in which a vertical frequency FIR filter is connected in series, the time axis FIR filter is practically 5
Since the limit is that the filter can be realized with about taps, the limit is about 7.5 Hz.

Further, the band limitation in the vertical direction needs to be limited to 240 TVL in order to multiplex the horizontal high frequency component Hh in the hole (color conjugate position) as shown in FIG.

The band-limited Hh component is shifted to a frequency of 2 to 4 MHz by the modulator 4 and multiplexed at the hole position shown in FIG. Then, in the adder 5, the luminance signal Y of the main signal and the signal Hh ′ modulated by the modulator 4 are added, and signal multiplexing is performed.

As described above, the signal level automatically changes between the moving image and the still image without switching the motion adaptively, so that the problem of the motion detection mismatch on the transmitting and receiving side does not occur unlike the conventional case. .

FIG. 5 is a block diagram of the receiving side. The decoder on the receiving side in FIG. 5 is the same as the decoder applied to the conventional motion adaptive encoder shown in FIG.

In FIG. 5, the NTSC composite signal in which the horizontal high frequency components are multiplexed at the conjugate position of the color signal C as shown in FIG. 3 is input to the Y / C separation circuit 6 and the motion detection circuit 7, respectively. In the Y / C separation circuit 6, Y component and C + H
The h'component is separated and the Y component is input to the adder 23.

The C + Hh 'component is input to the C / Hh' separation circuit 8 to separate the C component and Hh '. As shown in FIG. 3, the characteristics of the separation circuit 8 are as follows.
It has a characteristic of separating the Hh 'component of the hole portion between the two and the C component other than that, and is disclosed, for example, in "Multi-dimensional signal processing of TV", published by Nikkan Kogyo Shimbun, by Takahiko Fukibuki. A circuit can be used.

The Hh 'component is shifted to the base band band by the demodulator 9 and becomes the other input of the adder 23 via the static / dynamic changeover switch 22. Further, the C component is input to the demodulator 11 via the static / dynamic changeover switch 10 and demodulated. Further, the C + Hh 'component of the Y / C separation circuit 6 is the switch 10
Is input to the demodulator 11 via and is demodulated. The demodulator 11 generates I and Q signals.

The static / moving changeover switches 10 and 22 are controlled by the motion detection signal of the motion detection circuit 7, and when a still image is displayed,
The demodulated signal Hh of the demodulator 9 is added to the adder 2 via the switch 22.
3 and is added to the Y signal of the main signal to be derived.
When moving images, vertical-time L on the encoder side in FIG. 1
Due to the time-frequency band limitation by PF3, it can be considered that the Hh 'component is hardly multiplexed, so that the switch 2
2 is switched to the ground side.

[0030]

As described above, according to the present invention, the horizontal high frequency component is band-limited by using the vertical-time frequency band limiting filter so that the signal is automatically detected without using the motion detection. By changing the level, it is possible to eliminate the motion detection mismatch between transmission and reception.

[Brief description of drawings]

FIG. 1 is a block diagram of a transmitting side according to an embodiment of the present invention.

FIG. 2 is a diagram showing characteristics of a vertical-time LPF 3 of the block of FIG.

FIG. 3 is a diagram showing a method of multiplexing a color signal and a horizontal high frequency component.

FIG. 4A is a signal spectrum 31 and L for a still image.
FIG. 5 is a diagram showing a relationship with the characteristics of the PF3, and FIG. 9B is a diagram showing a relationship between the signal spectrum 31 at the time of moving image and the characteristics of the LPF3.

FIG. 5 is a block diagram of a receiving side according to the embodiment of the present invention.

FIG. 6 is a block diagram showing an example of a conventional television signal transmitting apparatus (encoder).

FIG. 7 is a block diagram showing another example of a conventional television signal transmitting apparatus (encoder).

[Explanation of symbols]

 1 horizontal LPF 2 horizontal HPF 3 vertical-time LPF 4 modulator 5 adder 6 Y / C separation circuit 7 motion detection circuit 8 C / Hh ′ separation circuit 9, 11 demodulator 10, 22 static / dynamic changeover switch

Claims (3)

[Claims] 1. A transmission device for multiplexing a luminance horizontal high-frequency signal on a television signal and transmitting the multiplexed signal, wherein high-pass filter means for extracting the horizontal high-frequency signal from the luminance signal and vertical-temporal frequency of the extracted output. A low-pass filter means for band-limiting the area and this band-limited output is 4.2 MHz.
A television signal transmitting apparatus comprising: a modulation means for softening the frequency within a band and an addition means for adding the modulated output to a luminance component of a main signal. 2. The television according to claim 1, wherein the modulator comprises a modulator for multiplexing the band-limited output of the low-pass filter at a position conjugate with the modulated color signal in the vertical-time frequency domain. John signal transmitter. 3. A television transmission signal in which a luminance horizontal high frequency signal is multiplexed at a position conjugate with a modulation chrominance signal in the vertical-time frequency domain, and the multiplexed signal and the luminance signal of the main signal are added. A television receiving device for receiving the television transmission signal and separating from the received signal signals other than the luminance signal of the main signal; and the vertical-time frequency domain from the separated output. And an extracting means for extracting a luminance horizontal high frequency signal multiplexed at a position conjugate with the modulated color signal, a demodulating means for demodulating the extracted output and converting it into a baseband signal, and the received signal being a moving image or a still image. A television signal receiving apparatus comprising: a motion detecting means for detecting whether or not, and a means for controlling the addition of the demodulated output to the luminance signal of the main signal according to the detected output.