JPH08149422A - Muse signal processor - Google Patents

Abstract

PURPOSE: To provide a MUSE signal processor which controls the output signals in a non-synchronous period. CONSTITUTION: A synchronous deciding circuit 4 decides a synchronous or non-synchronous state based on the detection result of a frame pulse detector 3. An extending circuit 102 extends the non-synchronous period into a certain fixed period to control a selecting circuit 103 so that a background color B 101 is outputted in the extended non-synchronous period and a background color A100 is outputted in the periods other than the non-synchronous period respectively. A selection circuit 104 selects the video output of a signal processing circuit 2 in the synchronous period and then selects the output signal of the circuit 103 in the non-synchronous period. Thus the background colors are controlled in two steps, i.e., a black color is decided when an originating station is switched and a blue color is decided when no signal exists. As a result, the unnecessary misunderstanding can be eliminated and the grade of a MUSE signal processor is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to MUSE (Multiple Sub-Nyquist Sampling Encoding:
The present invention relates to a circuit which is used in a decoder of a (multiple sub-sample transmission) system and controls an output signal when a broadcasting transmitting station is switched or when there is no input signal to the decoder.

[0002]

2. Description of the Related Art In recent years, high-definition broadcasting has been put into practical use,
Broadcasting by the MUSE system using satellites has started. M
Details of the USE method are described in Ninomiya “MUSE-High-Vision Transmission Method” edited by The Institute of Electronics, Information and Communication Engineers.

Hereinafter, a conventional MUSE will be described with reference to the drawings.
An example of the signal processing device will be described.

FIG. 4 is a block diagram showing an example of the MUSE signal processing device. In FIG. 4, reference numeral 1 is an A / D converter, which converts an input analog video signal into a digital signal. A signal processing circuit 2 restores a compressed signal to an original video signal by an interpolation process or the like by sub-sampling. Reference numeral 3 denotes a frame pulse detection circuit, which detects a frame pulse serving as a reference for synchronization by the MUSE method. Reference numeral 4 is a synchronization determination circuit, which determines from the result of the frame pulse detection circuit 4 whether there is erroneous detection or no synchronization, and outputs the result. 5
Is the background color setting. A selection circuit 6 switches the output signal of the signal processing circuit 2 and the background color 5 by the output signal of the synchronization determination circuit 4. A D / A converter 7 converts a digital signal into an analog signal and outputs it.

In the conventional MUSE signal processing device configured as described above, the result detected by the frame pulse detection circuit 3 in the synchronization determination circuit 4 is continuously several frames (for example, 6 frames).
It is determined that the synchronization is lost when no detection is performed for a period of about 9 frames from the frame) and erroneous detection due to noise or the like is sometimes performed when no detection is performed for one or two frame periods. The selection circuit 6 selects the video signal restored by the signal processing circuit 2 during the period when it is determined that there is synchronization based on the determination signal, and selects the background color 5 during the period when it is determined that there is no synchronization.

As described above, the quality of the signal processing device is improved without outputting a distorted image by outputting a certain background color on the screen during the period without synchronization. The background color 5 is often blue, as is often used in NTSC television receivers and video cassette recorders. This is to facilitate the determination of the presence / absence of a signal input to the device.

[0007]

However, in the above-mentioned configuration, when the broadcasting transmission station is switched while receiving the MUSE type video signal by satellite broadcasting, the phase of the video signal is changed before and after the switching. Since it is different, it is always determined that the synchronization is lost. Therefore, at that moment, a bluish background color is output, which may lead to misunderstanding that the signal processing device may be out of order, and the signal processing device is degraded in quality.

In view of the above problems, the present invention provides two or more background colors, a time corresponding to a non-synchronization period required when switching a broadcasting station, and a time after that.
An object of the present invention is to provide a MUSE signal processing device that enhances the quality of a signal processing device without causing misunderstanding by switching the background color in two steps.

[0009]

In order to achieve this object, the present invention provides a frame pulse detection circuit, a synchronization determination circuit connected to the frame pulse detection circuit, and a spreading circuit connected to the synchronization determination circuit. And a first selection circuit for switching the background color by the output signal of the widening circuit, and a second selection circuit for switching the signal-processed video signal and the output signal of the first selection circuit by the output signal of the synchronization determination circuit. It consists of a circuit.

[0010]

With the above-described structure, the present invention outputs the black background color during the time period corresponding to the non-synchronization period required when switching the broadcasting station, and thereafter outputs the blue background color as before. can do. Further, when there is no input signal, a black background color is output for a moment, but since it immediately changes to a blue background color, the presence / absence of an input signal can be easily determined as in the conventional case.

[0011]

DETAILED 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 MUSE signal processing device. In FIG. 1, 1 is an A / D converter, 2 is a signal processing circuit, 3 is a frame pulse detection circuit, 4 is a synchronization determination circuit,
Reference numeral 7 is a D / A converter, which is similar to the conventional example. 100
Is a generating means for outputting the background color A, 101 is a generating means for outputting the background color B, and sets different background colors. In this embodiment, an example in which two types of background colors are switched is shown. 102
Is a widening circuit, and outputs a control signal fixed for several frame periods immediately after it is determined from the determination output signal of the synchronization determination circuit 4 that there is no synchronization. 103 is a first selection circuit,
The background color A100 and the background color B101 are switched and output according to the output control signal of the spreading circuit 102. Reference numeral 104 denotes a second selection circuit, which outputs the output video signal of the signal processing circuit 2 and the first selection circuit 103 according to the output determination signal of the synchronization determination circuit 4.
The output signal of is switched and output.

Regarding the embodiment configured as described above,
The operation will be described below. The synchronization determination circuit 4 determines the presence or absence of synchronization as described in the conventional example, and outputs the result. FIG. 2A shows an example of the signal, which is a low level signal when there is synchronization and a high level signal when there is no synchronization. On the basis of this synchronization determination signal, the expansion circuit 102 outputs a control signal that holds the high level for several frame periods from the time when the low level changes to the high level (with synchronization). FIG. 2B is an example of the signal. In this high level period, a time longer than the period required for detecting and determining new synchronization from the determination of no synchronization is set. For example, the period is 8 frame periods.

The first selection circuit 103 is a widening circuit 102.
The background color B101 is selected while the output signal of is high level, and the background color A100 is selected during the low level period. In this case, the background color B101 is set to black and the background color B101 is set to blue. The second selection circuit 104 selects the output signal of the first selection circuit while the output signal of the synchronization determination circuit 4 is at a high level, and the signal processing circuit 2 during a low level.
Select the output video signal of. As a result, the output signal at the time of switching the transmitting station becomes as shown in FIG.

On the other hand, FIG. 3 shows an example when the input is a no signal. The output of the synchronization determination circuit 4 holds a high level for a period of no signal, and the output of the spreading circuit 102 holds a high level for a set number of frame periods. Therefore, immediately after the absence of signal, a black background color is output for a few frame periods, and then a bluish background color is output (see FIG. 3).
(C)).

As described above, the present embodiment has the effect that the image is not disturbed even when the transmitting station is switched and the viewer is not distrusted.

[0016]

As described above, according to the present invention, the frame pulse detection circuit, the synchronization determination circuit connected to the frame pulse detection circuit, the expansion circuit connected to the synchronization determination circuit, and the background color A A first selection circuit for switching the background color B by the output signal of the widening circuit, and a second selection circuit for switching the signal-processed video signal and the output signal of the first selection circuit by the output signal of the synchronization determination circuit. By providing a circuit, when switching the broadcasting station,
Between the video signals before and after the switching, for example, only the black background color is output, and when the input signal disappears, the first several frame periods are black, but after that, the blue background color is output. As a result, even when the source station is switched,
It is possible to maintain the dignity of the signal processing device without making the viewer misunderstand that the signal processing device is out of order.

[Brief description of drawings]

FIG. 1 is a block diagram of a MUSE signal processing device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a signal waveform in the MUSE signal processing device; (a) a waveform diagram of a synchronization determination signal; (b) a waveform diagram of an output signal of a spreading circuit; (c) a waveform diagram of an output signal.

FIG. 3 is a diagram showing another example of signal waveforms in the MUSE signal processing device. (A) Waveform diagram of synchronization determination signal (b) Waveform diagram of output signal of spread circuit (c) Waveform diagram of output signal

FIG. 4 is a block diagram showing a configuration of a conventional MUSE signal processing device.

[Explanation of symbols]

 3 frame pulse detection circuit 4 synchronization determination circuit 100 background color A 101 background color B 102 widening circuit 103 first selection circuit 104 second selection circuit

Claims (1)

[Claims] 1. A frame pulse detection circuit, a synchronization determination circuit connected to the frame pulse detection circuit, a widening circuit connected to the synchronization determination circuit, and several kinds of background colors are switched by an output signal of the widening circuit. The MUSE is provided with a first selection circuit, and a second selection circuit for switching the signal-processed video signal and the output signal of the first selection circuit according to the output signal of the synchronization determination circuit.
Signal processing device.