JP2003318790A - Diversity apparatus for video receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diversity apparatus for a video receiver, which prevents the disturbance of a video generated, immediately after antenna switching by always switching antennas during a vertical synchronizing period, regardless of the radio wave conditions. <P>SOLUTION: The apparatus has at least a plurality of antennas, means for switching the antennas, means for detecting a synchronization signal of the video from a received video signal, means for deciding whether the detected synchronization signal of the video is normal, and means for generating an internal synchronization signal which is synchronized with the detected synchronization signal of the video. When synchronization signal of the video detected from the received video signal is normal, the apparatus switches the antennas during the vertical synchronizing period of the video, by the synchronization signal of the video detected from the received video signal. When synchronization signal of the video detected from the received video signal is abnormal, the means for generating an internal synchronization signal which is synchronized with the detected synchronization signal of the video continuously generates the internal synchronization signal, and the apparatus switches the antennas during the vertical synchronization period of the video, by the internal synchronization signal. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity device for a video receiver, which receives a video signal such as a television signal.

[0002]

2. Description of the Related Art A receiver for receiving a video signal is provided with a plurality of antennas in order to receive the video in a better condition, that is, in a condition in which the image is less disturbed, and the receiving condition depends on the radio wave condition such as electric field strength. A method of selecting and receiving an antenna with good reception, that is, a spatial diversity method is used.

When an antenna with a good reception state is selected and switched to an antenna with a good reception state, the radio wave state such as the electric field strength is different before and after the switching, so that an unstable state occurs immediately after switching. This unstable state affects the video signal and causes the video to be disturbed.

As a method of eliminating the image disturbance due to the antenna switching, there is a method of switching the antenna during the vertical synchronization period of the video signal.

FIG. 1 is a block diagram showing a diversity device of a conventional video receiver, which includes an antenna 11, a switching unit 12, a receiving unit 13, a level detecting unit 14, and a synchronization detecting unit 1.
5, the switching control unit 16.

Radio waves received from the antenna 11 are input to the receiving unit 13 and the level detecting unit 14 via the switching unit 12. The receiver 13 demodulates the input signal (radio wave) into a video signal and outputs it to the synchronization detector 15. The synchronization detection unit 15 detects the vertical synchronization period from the demodulated video signal and outputs a signal indicating the vertical synchronization period to the switching control unit 16.

On the other hand, in the level detector 14, the antenna 1
1, the electric field strength of the electric wave received through the switching unit 12 is detected and output to the switching control unit 16.

In the switching control unit 16, the level detection unit 1
Based on the input from 4, it is determined whether or not the antenna should be switched, and when it is necessary to switch the antenna, the signal is output to the switching unit 12 in synchronization with the signal from the synchronization detection unit 15, that is, during the vertical synchronization period. , Switch the antenna.

[0009]

By switching the antenna during the vertical synchronization period, it is possible to eliminate the unstable state immediately after switching, that is, the disturbance of the image. Reliable detection is required. However, since the vertical synchronization period is also detected from the received radio wave, there are many unstable factors.

In other words, it is quite possible that the vertical synchronization period cannot be detected due to a decrease in electric field strength, fading phenomenon that is always associated with radio wave transmission and reception. A decrease in electric field strength, fading phenomenon, etc. often occur due to changes in the surrounding environment. Even if there is no change in the transmitter status or receiver status, it may occur and the vertical synchronization period may not be detected. .

If the vertical synchronization period cannot be detected, the timing for switching the antenna is lost, and the antenna cannot be switched or the antenna must be switched at an arbitrary timing.

When the antennas cannot be switched, the antennas are not switched and the reception is continued in a poor reception state, which causes the image to be disturbed. When the antenna is switched at an arbitrary timing, an unstable state occurs immediately after switching as described above, which affects the video signal and disturbs the video.

Further, it is fully conceivable to receive radio waves from other radio equipment, and the radio waves from other radio equipment may
The vertical sync period could not be detected accurately, resulting in incorrect timing,
That is, the antenna may be switched outside the vertical synchronization period, and it is sufficiently possible that an unstable state occurs and the image is disturbed.

In view of the above problems, the present invention provides a diversity apparatus for a video receiver, which always switches the antennas during the vertical synchronization period regardless of the radio wave condition and eliminates the disturbance of the video generated immediately after switching the antennas. It is an object.

[0015]

In a diversity device of a video receiver, at least a plurality of antennas, means for switching the antennas, means for detecting a video synchronization signal from the received video signal, and synchronization of the detected video. It has a means for judging whether the signal is normal and a means for generating an internal synchronizing signal synchronized with the detected video synchronizing signal, and the video synchronizing signal detected from the received video signal is normal. In this case, the antenna is switched during the vertical synchronization period of the video by the video synchronization signal detected from the received video signal, and if the video synchronization signal detected from the received video signal is abnormal, it is detected. The means for generating an internal synchronization signal synchronized with the video synchronization signal continuously generates the internal synchronization signal, and the internal synchronization signal causes an unsynchronization during the vertical synchronization period of the video. The diversity device of the video receiver to perform Na switching.

In the diversity device of the video receiver, at least a plurality of antennas, means for switching the antennas, means for detecting a video synchronization signal from the received video signal, and whether the detected video synchronization signal is normal or not. It has means for judging whether or not it has, and means for generating an internal synchronizing signal synchronized with the synchronizing signal of the detected video, and when the synchronizing signal of the video detected from the received video signal is normal, it is received. The antenna is switched during the vertical synchronization period of the video by the video synchronization signal detected from the video signal, and if the video synchronization signal detected from the received video signal is abnormal, it is synchronized with the detected video synchronization signal. The means for generating the internal synchronization signal continuously generates an internal synchronization signal having a constant cycle, and the antenna is used during the vertical synchronization period of the image by the internal synchronization signal. The diversity device of the video receiver to perform Rikae.

In the diversity device of the video receiver, at least a plurality of antennas, means for switching the antennas, means for detecting a video sync signal from the received video signal, and whether the detected video sync signal is normal or not. It has means for determining whether or not it has, means for generating an internal synchronization signal in synchronization with the detected video synchronization signal, and means for detecting the cycle of the video synchronization signal from the detected video synchronization signal. If the video sync signal detected from the video signal is normal, the antenna is switched during the vertical sync period of the video by the video sync signal detected from the received video signal, and the video detected from the received video signal If the sync signal of the video signal is abnormal, the means for generating the internal sync signal synchronized with the sync signal of the detected video continues to It generates an internal synchronization signal cycle obtained from the means for detecting the period, the diversity device of the video receiver to perform antenna switching in the vertical synchronizing period of the video by the internal synchronization signal.

[0018]

2 is a block diagram showing a first embodiment of the present invention, and FIG. 3 is a block diagram for explaining the operation of the internal synchronizing signal generator 29 in FIG. The diversity device of the video receiver includes an antenna 21, a switching unit 22,
The reception unit 23, the level detection unit 24, the synchronization detection unit 25, the switching control unit 26, the synchronization signal determination unit 28, and the internal synchronization signal generation unit 29.

The radio wave received from the antenna 21 is input to the receiving unit 23 via the switching unit 22 and demodulated into a video signal by the receiving unit 23. The demodulated video signal is input to the sync detector 25 to generate a vertical sync signal indicating a vertical sync period. The vertical synchronization signal is the synchronization signal determination unit 28.
And determines whether the input vertical synchronizing signal is normal.

The method of judging the input vertical synchronizing signal in the synchronizing signal judging section 28 is as follows. The cycle of the vertical synchronizing signal of the video signal to be transmitted or received is fixed, and the cycle of the normal vertical synchronizing signal is almost constant. For example NT
In the case of SC video signal, the cycle of the vertical synchronizing signal is 16.68.
It is determined to be mS. Therefore, if the cycle of the input vertical synchronizing signal is not 16.68 mS, it is determined that the vertical synchronizing signal is abnormal. In reality, since the video signal also varies, 16.68 mS should be given a proper width, and if within the range, it is determined that the vertical sync signal is normal, and if it is out of the range or the vertical sync signal is not input, the vertical sync signal is abnormal.

The result determined by the synchronization signal determination unit 28 is
It is input to the internal synchronization signal generator 29.

The internal sync signal generator 29 includes a sync detector 2
A vertical synchronizing signal is also inputted from 5 to generate an internal vertical synchronizing signal. A method of generating the internal vertical synchronizing signal will be described with reference to FIG.

The internal synchronizing signal generator 29 is provided with a switch A3.
The vertical sync signal output from the sync detector 25 and the determination result output from the sync signal determiner 28 are input.
The timer-33 is set in advance to generate a signal at a constant cycle. For example, the period is set to 16.68 mS in accordance with the vertical synchronizing signal of the NTSC video signal.

When the input judgment result is normal, both the switch A31 and the switch B32 select the a side. The vertical synchronizing signal input by the switch B32, that is, the vertical synchronizing signal of the received video signal is output as it is. On the other hand, the switch A31 clears the timer 33 each time by the input vertical synchronization signal, and synchronizes the start of a preset cycle with the input vertical synchronization signal.

When the input judgment result is abnormal, both the switch A31 and the switch B32 select the b side. The switch B32 outputs an output from the timer 33, that is, a signal having a constant cycle in synchronization with the vertical synchronizing signal of the video signal received until immediately before. On the other hand, the switch A31 clears the timer 33 at a constant cycle, and a signal at a constant cycle is continuously generated.

The switching control unit 26 receives the antenna 21 and determines whether or not to switch the antenna based on the input from the level detection unit 24 which detects the electric field strength of the radio wave via the switching unit 22 and switches the antenna. When necessary, the signal is output to the switching unit 22 in synchronization with the signal from the internal synchronization signal generation unit 29, and the antenna is switched.

As a result, when the video sync signal detected from the received video signal is normal, the antenna is switched during the vertical sync period of the video by the video sync signal detected from the received video signal. If the video sync signal detected from the received video signal is abnormal,
It is possible to perform antenna switching in synchronization with the vertical synchronizing signal of the detected video and at a constant cycle.

FIG. 4 is a block diagram showing a second embodiment of the present invention, which is constructed by adding a period measuring unit 41 to the first embodiment of the present invention.

As in the first embodiment of the present invention, the antenna 2
The electric wave received from 1 passes through the switching unit 22,
It is input to the receiving unit 23 and demodulated into a video signal in the receiving unit 23. The demodulated video signal is input to the sync detector 25 to generate a vertical sync signal indicating a vertical sync period. The vertical synchronization signal is input to the synchronization signal determination unit 28, and it is determined whether the input vertical synchronization signal is normal. The result determined by the synchronization signal determination unit 28 is input to the internal synchronization signal generation unit 29.

The vertical synchronization signal output from the synchronization detection unit 25 and the result determined by the synchronization signal determination unit 28 are also input to the period measurement unit 41, and when the vertical synchronization signal is normal, the period of the vertical synchronization signal is measured. And outputs it to the internal synchronization signal generator 29.

In the internal sync signal generator 29, the output of the cycle measurement unit 41, that is, the cycle of the video sync signal detected from the received video signal is stored in the internal sync signal generator 29 when the vertical sync signal is normal. It is taken into a certain timer 33.

As a result, the internal synchronizing signal generator 29 is
If the input determination result is normal, the input vertical synchronization signal, that is, the vertical synchronization signal of the received video signal is output as it is, and if the input determination result is abnormal,
An output from the timer 33, that is, a signal having the same cycle as the vertical synchronizing signal of the video signal received until immediately before, which is synchronized with the vertical synchronizing signal of the video signal received until immediately before, is output.

The switching control unit 26 receives the signal from the antenna 21 as in the first embodiment of the present invention, and the switching unit 2
When it is necessary to switch the antenna, it is determined whether or not the antenna should be switched based on the input from the level detection unit 24 that detects the electric field strength of the radio wave passing through 2.
The signal is output to the switching unit 22 in synchronization with the signal from the internal synchronization signal generation unit 29, and the antenna is switched.

As a result, when the video sync signal detected from the received video signal is normal, the antenna is switched during the vertical sync period of the video by the video sync signal detected from the received video signal. If the video sync signal detected from the received video signal is abnormal,
It is possible to perform antenna switching in synchronization with the vertical sync signal of the detected video and at the cycle of the vertical sync signal of the detected video.

[0035]

According to the present invention, it is possible to always switch the antennas during the vertical synchronization period, and it is possible to eliminate the disturbance of the image that occurs immediately after switching the antennas.

Even when the reception state temporarily deteriorates and the image is disturbed, the antenna can be switched during the vertical synchronization period, so that the normal image can be quickly returned.

Since the antennas cannot be switched or the antennas can be prevented from being switched at an arbitrary timing, the image is not disturbed by continuing the reception while the reception condition is bad or causing an unstable state.

According to the third aspect of the present invention, the antenna can be switched according to the period of the vertical synchronizing period of the received video signal. Therefore, even if the reception state is bad for a long time, it occurs immediately after switching the antenna. It is possible to eliminate the image distortion.

[Brief description of drawings]

FIG. 1 is a block diagram showing a diversity device of a conventional video receiver.

FIG. 2 is a block diagram showing a first embodiment of the present invention.

FIG. 3 is an internal synchronization signal generator 2 in the first embodiment of the present invention.
9 is a block diagram illustrating the operation of FIG.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

[Explanation of symbols]

11 antenna 12 Switching unit 13 Receiver 14 Level detector 15 Sync detector 16 Switching control unit 21 antenna 22 Switching unit 23 Receiver 24 Level detector 25 Sync Detector 26 Switching control unit 28 Sync signal determination unit 29 Internal sync signal generator 31 Switch A 32 Switch B 33 timer 41 Period measurement unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshio Yoda             No. 4107, Miyota, Miyota-cho, Kitasaku-gun, Nagano Prefecture             Ground 5 Miyota Co., Ltd. (72) Inventor Yasushi Shinohara             No. 4107, Miyota, Miyota-cho, Kitasaku-gun, Nagano Prefecture             Ground 5 Miyota Co., Ltd. F-term (reference) 5C025 AA22 BA13                 5K059 CC03 DD01 DD27 EE01

Claims (3)

[Claims] 1. A diversity device for a video receiver, wherein at least a plurality of antennas, means for switching the antennas, means for detecting a video synchronizing signal from the received video signal, and the detected video synchronizing signal are normal. There is a means for determining whether or not there is, and a means for generating an internal synchronization signal synchronized with the synchronization signal of the detected video, and when the synchronization signal of the video detected from the received video signal is normal, If the antenna is switched during the vertical synchronization period of the video according to the video synchronization signal detected from the received video signal, and the video synchronization signal detected from the received video signal is abnormal, the detected video synchronization signal The means for generating the internal synchronization signal synchronized with the signal continuously generates the internal synchronization signal, and the antenna switching is performed in the vertical synchronization period of the image by the internal synchronization signal. Diversity system of the video receiver, characterized in that. 2. The method according to claim 1, wherein the means for generating an internal synchronizing signal synchronized with the detected synchronizing signal of the image continues when the synchronizing signal of the image detected from the received image signal is abnormal. A diversity device for a video receiver, which is characterized by generating an internal synchronization signal having a constant cycle. 3. The video signal detected by the received video signal according to claim 1, further comprising means for detecting a cycle of the video sync signal obtained by the means for detecting the video sync signal from the received video signal. If the sync signal is normal, the means for obtaining the cycle of the sync signal from the means for detecting the cycle of the sync signal of the video, and the means for generating the internal sync signal synchronized with the sync signal of the detected video are received. Video reception, characterized in that, when the video sync signal detected from the video signal is abnormal, the internal sync signal is generated at the cycle obtained from the means for continuously detecting the cycle of the video sync signal. Machine diversity equipment.