JPH06153162A - Television signal processing circuit - Google Patents

Abstract

PURPOSE:To prevent a picture from being deteriorated by reducing noise when a reception state (C/N) is deteriorated more than a prescribed level in a high definition television signal subject to band compression. CONSTITUTION:The processing circuit is provided with a transmission noise detection circuit 14 detecting a reception state, a moving picture processing circuit 6 processing a moving picture, a still picture processing circuit 7 processing a still picture, a motion detection circuit 5 detecting a motion, a mixer circuit 8 mixing a moving picture and a still picture and a motion signal control circuit 13 controlling the output of the motion signal, and the motion signal is made zero with an output of the transmission noise detection circuit 14 when the reception state (C/N) is deteriorated to select the output of the mixer circuit 8 for the still picture processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal processing circuit for band-compressed high-definition television signals.

[0002]

2. Description of the Related Art In recent years, there has been an increasing interest in a TCI transmission system in which color signals are time-division multiplexed in order to efficiently transmit a wideband television signal within a limited transmission band.
For example, as one of the TCI transmission methods, MUSE that band-compresses high-definition television (high-definition) signals
The (Multiple Sub-Nyquist Sampling Encoding) method has been proposed by the Japan Broadcasting Corporation (NHK). For details of the contents, refer to Yuichi Ninomiya et al., "High-definition Television Satellite 1-Channel Transmission System (MUSE)" (SIJ, Technical Report, IE
84-72.1984).

A conventional television signal processing circuit will be described below with reference to the drawings.

FIG. 3 is a block diagram of a conventional television signal processing circuit. In FIG. 3, 1 is an input terminal for a MUSE signal, 2 is a low-pass filter for band limiting, 3 is an A / D conversion circuit for converting into a digital signal, 4 is a synchronous processing circuit for detecting a synchronous signal, and 5 is a motion. A motion detection circuit for detecting, 6 is a moving image processing circuit for processing a moving image, 7
Is a still image processing circuit for processing a still image, 8 is a mixing circuit for mixing moving images and still images, 9 is a color processing circuit for decoding time-division multiplexed line-sequential color signals, and 10 is a luminance signal and a color difference signal. An inverse matrix conversion circuit for performing more inverse matrix conversion, 11 is a D / A conversion circuit for converting into an analog signal, and 12 is an audio processing circuit for extracting an audio part and converting into an audio signal.

The operation of the television signal processing circuit configured as described above will be described below. Figure 3
The MUSE signal input to the input terminal 1 of the above is band-limited to 8.1 MHz or less by the low-pass filter 2 and then converted into a 10-bit digital signal by the A / D conversion circuit 3. The synchronization processing circuit 4 detects a synchronization signal (frame pulse) from the digital signal and outputs a synchronization detection signal. The motion detection circuit 5 detects the amount of motion for each pixel from the digital signal. Further, the moving image processing circuit 6 performs two-dimensional interpolation processing on the digital signal. In the still image processing circuit 7, the digital signal is subjected to noise reduction,
Interpolation between frames and band limitation are performed. The mixing circuit 8 mixes the output of the moving image processing circuit 6 and the output of the still image processing circuit 7 with the amount of motion output from the motion detection circuit 5. The color processing circuit 9 mixes the output of the moving image processing circuit and the output of the still image processing circuit according to the amount of motion output from the motion detection circuit, and further time-division-compressed and multiplexed line-sequential color difference signals. Is extracted, expanded, and decoded to be converted into color difference signals (RY, BY). Next, the inverse matrix conversion circuit 10 performs an inverse matrix on the luminance signal output from the mixing circuit 8 and the color difference signal output from the color processing circuit 9, and the G.G. B. Convert to R signal. Further, the D / A conversion circuit 11 converts the analog signal and outputs a high-definition signal (GBR). The voice processing circuit 12 extracts a voice portion from the digital signal, detects voice synchronization, and converts it into a voice signal.

[0006]

However, in the above-mentioned conventional method, the reception state (Carrier / Noise or less C
There is a problem that there is a lot of noise such as when / N) is considerably bad, and the noise is conspicuous due to moving image processing and is very unsightly.

The present invention solves the above-mentioned problems of the prior art, and when the reception condition (C / N) is considerably poor, noise is suppressed and image deterioration is prevented.

[0008]

In order to achieve this object, a television signal processing apparatus of the present invention is provided with a transmission noise detection circuit and a motion signal control circuit, and is provided with a reception state (C / N).
If is lower than a predetermined level, the signal is switched to a signal for still image processing in which noise is suppressed.

[0009]

With this configuration, when the reception state (C / N) is worse than the predetermined level, the output of the transmission noise detection circuit causes the motion signal control circuit to set the motion signal to zero (still image) and switch to the still image. Noise can be suppressed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a conventional television signal processing circuit. FIG. 2 is a configuration diagram of a transmission signal of band compression (MUSE method), (a) is a schematic diagram, and (b) is a detailed diagram. In FIG. 1, 1 is an input terminal for a MUSE signal, 2 is a low pass filter for band limiting, 3 is an A / D conversion circuit for converting to a digital signal, 4 is a synchronous processing circuit for detecting a synchronous signal, and 5 is a motion. A motion detection circuit for detection, 6 is a moving image processing circuit for processing moving images, 7 is a still image processing circuit for processing still images, 8 is a mixing circuit for mixing moving images and still images, and 9 is time division multiplexed. A color processing circuit for decoding a line-sequential color signal, 10 an inverse matrix conversion circuit for performing an inverse matrix conversion from a luminance signal and a color difference signal, 11 a D / A conversion circuit for converting an analog signal,
Reference numeral 12 is a voice processing circuit for extracting a voice portion and converting it into a voice signal, 13 is a motion signal control circuit for controlling a motion signal, 14
Is a transmission noise detection circuit for detecting the reception state (C / N).

The operation of the television signal processing circuit configured as described above will be described below. Figure 1
The MUSE signal input to the input terminal 1 of the above is band-limited to 8.1 MHz or less by the low-pass filter 2 and then converted into a 10-bit digital signal by the A / D conversion circuit 3. The synchronization processing circuit 4 detects a synchronization signal (frame pulse) as shown in FIG. 2 from the digital signal. In the transmission noise detection circuit 14, for example, several tens of samples are sampled from a clamp level or a frame pulse whose level is regulated by the digital signal as shown in FIG. 2 and the level is regulated, and then compared with the regulated level, and the difference is small. For example, it is determined that the transmission noise is small (the reception state is good), and if the difference is large, the transmission noise is large (the reception state is bad), a certain threshold value is set and a detection signal is output. Motion detection circuit 5
Then, the amount of motion is detected for each pixel from the digital signal. Further, the moving image processing circuit 6 performs two-dimensional interpolation processing on the digital signal. The still image processing circuit 7 performs noise reduction, interframe interpolation and band limitation on the digital signal. The mixing circuit 8 mixes the output of the moving image processing circuit 6 and the output of the still image processing circuit 7 with the amount of motion output from the motion detection circuit 5. Further, in the color processing circuit 9, the output of the moving image processing circuit 6 and the output of the still image processing circuit 7 are mixed according to the motion amount which is the output of the motion detecting circuit, and the time-sequential compression-multiplexed line sequential processing is performed. The color difference signal is extracted, expanded, decoded and converted into a color difference signal.

Here, in the motion signal control circuit 13, when the transmission noise detection circuit 14 detects that there is a lot of noise, a motion signal (luminance input to the mixing circuit 8) which is an output signal of the motion detection circuit 5 is detected. The motion signal and the color motion signal input to the color processing circuit 9 are set to zero (still image), and the mixing circuit 8 selects the output of the still image processing circuit 7. When the transmission noise detection circuit 14 detects that the noise is small, the motion signal (luminance motion signal and color motion signal) which is the output signal of the motion detection circuit 5 is output as it is, and the motion picture processing circuit 6 outputs the motion signal. The output and the output of the still image processing circuit 7 are mixed. Next, in the inverse matrix conversion circuit 10, an inverse matrix is performed with the luminance signal output from the mixing circuit 8 and the color difference signal output from the color processing circuit 9, and G.G. B. Convert to R signal. Furthermore, the D / A conversion circuit 1
1 is converted into an analog signal and converted into a high-definition signal (GB.
R) is output. The voice processing circuit 12 extracts a voice portion from the digital signal, detects voice synchronization, and converts it into a voice signal.

As described above, according to this embodiment, the motion signal control circuit 13 and the transmission noise detection circuit 14 are provided, and the reception state (C / N) is obtained by the output signal of the transmission noise detection circuit 14.
Is worse than a predetermined level, the motion signal is set to zero (still image), and the still image processing is selected by the mixing circuit 8 to display an image in which noise is suppressed by the noise reduction effect of the still image processing. You can

[0014]

As described above, the present invention provides a motion control circuit,
By providing a transmission noise detection circuit and stopping the motion signal (switching to still image processing) when the reception state (C / N) is worse than a predetermined level, an image with suppressed noise can be displayed.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a television signal processing circuit of the present invention in one embodiment.

FIG. 2 is a configuration diagram showing a mode of a transmission signal of band compression (MUSE method).

FIG. 3 is a block configuration diagram of a conventional television signal processing circuit.

[Explanation of symbols]

 1 MUSE signal input terminal 2 Low-pass filter 3 A / D conversion circuit 4 Synchronization processing circuit 5 Motion detection circuit 6 Video processing circuit 7 Still image processing circuit 8 Mixing circuit 9 Color processing circuit 10 Inverse matrix conversion circuit 11 D / A conversion circuit 12 audio processing circuit 13 motion signal control circuit 14 transmission noise detection circuit

Claims (1)

[Claims] 1. A circuit for receiving and processing a band-compressed high-definition television signal, a synchronization processing circuit for performing synchronization detection, a moving image processing circuit for processing a moving image, and a still image processing circuit for processing a still image. A motion detection circuit that performs motion detection, a mixing circuit that mixes moving images and still images, a motion signal control circuit that controls the output of motion signals, and a transmission noise detection circuit that detects the amount of noise in transmission,
A television characterized in that, when the reception condition (C / N) is worse than a predetermined level, the motion signal is switched to a still image through the motion signal control circuit by the detection output obtained from the transmission noise detection circuit. John signal processing circuit