JP2601145B2 - Television signal transceiver - Google Patents

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 and receiving apparatus, and more particularly to a 4.2 MHZ of the current television system.
The present invention relates to an EDTV (Enhanced TV) television transmission / reception device for transmitting a horizontal high-frequency component of 4.2 MHz or more in a 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 at 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 directly used as one input of the adder 5.

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

[0004] In this way, high-frequency components of 4.2 MHz or higher are multiplexed by being shifted to a frequency within 4.2 MHz and converted, and a specific method of this multiplexing is as follows. This is described in detail in "Transmission system of television signal" in JP-A-3-46475. That is, as shown in FIG. 3, the vertical-time frequency domain (ν-
f region), a chroma component (C) which is a color modulation signal
The horizontal high-frequency component (Hh ′) is multiplexed at a position conjugate with the above.

The position conjugate with the chroma component is referred to as a "hole" using the name of the inventor, and is shown as a hole in FIG.

In such a multiplexing method of high frequency components using a "hole", it is effective for a still image, but a luminance signal or a chrominance signal leaks into the hole during a moving image, and is thus multiplexed in the hole. Crosstalk with the converted components may occur.

[0007] Therefore, as shown in FIG.
2 is used to detect a moving image.
There is a method in which h is multiplexed, but adaptive processing is performed using the switch 13 so that the h is not multiplexed at the time of a moving image.

For example, Hirano et al., “EDTV Encoder Various Characteristics Using Current Interlaced Scanning Camera Signal”, Journal of the Institute of Television Engineers of Japan, Vol. 43, no. 5
(1989), pp. 505-512.

[0009]

When such a motion adaptation process as shown in FIG. 7 is performed, the receiving side also performs motion detection and does not add the horizontal high frequency component Hh to the main luminance signal at the time of a moving image. At the time of a still image, an adaptive process for adding is required.

[0010] However, since the signal properties of the transmitting side and the receiving side do not completely match, there is a case where the motion detection is mismatched in transmission and reception. This mismatch causes image quality degradation.

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. 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 caused by motion detection in transmission / reception by multiplexing a horizontal high-frequency component of 4.2 MHz or more in the band of a current television signal without motion adaptive processing. It is an object of the present invention to provide a television signal transmitting and receiving device capable of performing the above.

[0013]

SUMMARY OF THE INVENTION A television signal transmitting apparatus according to the present invention is a transmitting apparatus for transmitting a television signal by multiplexing a luminance horizontal high-frequency signal with the television signal, and extracting the horizontal high-frequency signal from the luminance signal. High-pass filter means for extracting the extracted output in the vertical-time frequency domain .
Low-pass filter means for band-limiting the frequency within the 7.5 Hz band, modulation means for frequency-softening the band-limited output within the 4.2 MHz band, and addition means for adding the modulated output to the luminance component of the main signal. It is characterized by including.

[0014] television signal receiving apparatus according to the present invention, the luminance horizontal high band signal, vertical - a time-frequency domain smell
A television receiving a television transmission signal in which the time frequency is band-limited within the 7.5 Hz band , multiplexed at a position conjugate to the modulated chrominance signal, and the multiplexed signal and the luminance signal of the main signal are added. A television receiver, comprising: a separating unit that receives the television transmission signal and separates a signal other than the luminance signal of the main signal from the received signal; and a modulation color signal in the vertical-time frequency domain from the separated output. Extracting means for extracting a luminance horizontal high-frequency signal multiplexed at a position conjugate to the above, demodulating means for demodulating the extracted output and converting it to a baseband signal, and detecting whether the received signal is a moving image or a still image It is characterized by including a motion detecting means, and means for adding and controlling the demodulated output to the luminance signal of the main signal in accordance with the detected output.

[0015]

Embodiments of the present invention will be described below in detail 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 denoted 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 a horizontal LPF 1 and a horizontal HPF 2 and separated and extracted into respective band components of 4.2 MHz or less and 4.2 MHz or more, respectively. .

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

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

At the time of a still image, the image signal spectrum 41 is attached to the ν axis and does not spread to the f axis as shown in FIG. This is because a still image has no signal change in the time direction and D
This is because only the C component is considered. Therefore, the signal spectrum 41 is limited only in the vertical direction in the LPF 3.

On the other hand, at the time of a moving image, as shown in FIG. 4B, there is a signal change in the time direction and the signal spectrum 41 spreads in the time direction. Therefore, most of the signal in the spectrum is cut.

Therefore, the characteristic 31 of the LPF 3 needs to have an extremely narrow band in the time axis direction. Therefore, in this embodiment, the frequency is limited to 7.5 Hz or less. In this case, the LPF 3 includes a time-frequency FIR filter,
This is realized by a series connection circuit configuration with a vertical frequency FIR filter.
Since it is the limit to realize the filter as a tap, 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 a hole (a conjugate position of a color) as shown in FIG.

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

As described above, the signal level automatically changes between the moving image and the still image even if the switching is not performed adaptively by the motion, so that the problem of the mismatch in the motion detection on the transmitting and receiving sides does not occur unlike the related art. .

FIG. 5 is a block diagram on the receiving side. The receiving side decoder 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 component is 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, the 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 a C / Hh' separation circuit 8, where the C component and Hh 'are separated. As shown in FIG. 3, the characteristic of the separation circuit 8 is a pair of dashed lines 81 and 8.
2, which has the property of separating the Hh 'component of the hole portion from the other components and the C component, and is disclosed in, for example, "Multi-dimensional signal processing of TV" published by Nikkan Kogyo Shimbun, Ltd. A circuit can be used.

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

The static changeover switches 10 and 22 are controlled by a motion detection signal of the motion detection circuit 7, and at the time of a still image,
The demodulated signal Hh from the demodulator 9 is supplied to the adder 2 via the switch 22.
3 is added to the Y signal of the main signal and is derived.
At the time of video, the vertical-time L on the encoder side in FIG.
Since the Hh 'component can be regarded as almost not multiplexed by the time frequency band limitation by the PF3, the switch 2
2 is switched to the ground side.

[0030]

As described above, according to the present invention, the band is limited to the horizontal high-frequency component using the vertical-time frequency band limiting filter, so that the signal can be automatically obtained without using motion detection. Since the level is changed, there is an effect that it is possible to eliminate the mismatch of motion detection between transmission and reception.

[Brief description of the 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 LPF3 of the block in FIG. 1;

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

FIG. 4 (a) shows a signal spectrum 31 and L during a still image.
FIG. 7B is a diagram illustrating a relationship between the characteristics of the PF3 and FIG. 7B is a diagram illustrating a relationship between the signal spectrum 31 and the characteristics of the LPF 3 during a moving image.

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

FIG. 6 is a block diagram illustrating an example of a conventional television signal transmission device (encoder).

FIG. 7 is a block diagram illustrating another example of a conventional television signal transmission device (encoder).

[Explanation of symbols]

 DESCRIPTION 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 / change switch

Claims (3)

(57) [Claims] 1. A transmitting apparatus for multiplexing a luminance horizontal high-frequency signal with a television signal and transmitting the multiplexed signal, comprising: high-pass filter means for extracting the horizontal high-frequency signal from the luminance signal; Time frequency in the domain
Low-pass filter means for band-limiting the signal within a 7.5 Hz band, modulation means for frequency-softening the band-limited output within a 4.2 MHz band, and addition means for adding the modulated output to the luminance component of the main signal. A television signal transmitting device, comprising: 2. The television according to claim 1, wherein said modulating means comprises a modulating means for multiplexing a band-limited output of said low-pass filter at a position conjugate with a modulated color signal in a vertical-time frequency domain. John signal transmitter. 3. The luminance horizontal high frequency signal has a time frequency band limited to a 7.5 Hz band in a vertical-time frequency domain .
A television transmission signal that is multiplexed at a position conjugate to the modulated chrominance signal and that is obtained by adding the multiplexed signal and the luminance signal of the main signal. Receiving means for separating a signal other than the luminance signal of the main signal from the received signal; and a luminance horizontal height multiplexed from the separated output at a position conjugate with the modulated chrominance signal in the vertical-time frequency domain. Extracting means for extracting a band signal, demodulating means for demodulating the extracted output to convert it to a baseband signal, motion detecting means for detecting whether the received signal is a moving image or a still image, and Means for controlling addition of a demodulated output to a luminance signal of the main signal.