JPH07162770A - Television network following system - Google Patents

Abstract

PURPOSE:To provide a television network following system not generating noise or deviation on a screen at the time of switching a reception channel. CONSTITUTION:This television network following system for searching the broadcasting station receiving the reception channel different from that of a reception station receiving television broadcasting at present and switching the reception channel to a changeover station having the same broadcasting contents as the reception station and electric field strength stronger than the electric field strength of the reception station is provided with a means 10 for turning off signals on the side of the reception station when the frame synchronizing signals of the video signals of the reception station under reception are detected and successively turning on the signals on the side of the changeover station when the frame synchronizing signals of the video signals of the changeover station are detected at the time of performing changeover from the reception station to the changeover station through switching circuits 7 and 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television network follow system.

[0002]

2. Description of the Related Art When receiving a television broadcast in a moving car, a television network follow system constantly searches for a station having the same broadcast content as the receiving station currently receiving, and the same station broadcasting the same broadcast content is searched. If the reception level of the same station is higher than the reception level of the reception station, the reception channel is automatically switched from the reception station side to the same station side. As a result, when an automatic person moves from the receiving area of one station to the receiving area of another station that broadcasts the same broadcast content, the receiving channel is automatically switched to the one with the higher receiving level, and the running position of the car Regardless of, you can always receive good TV broadcasts.

[0003]

In the conventional television network follow system, it is determined whether the broadcast content of the receiving station currently being received and the broadcast content of the searched station are the same or not. This was done by comparing the audio signals with each other. Therefore, the switching of the receiving channel is performed independently of the video signal, which may cause noise on the screen of the television or the screen may be displaced when switching between stations.

An object of the present invention is to provide a television network follow system in which noise does not occur on the screen when the receiving channel is switched and the screen does not shift.

[0005]

In order to achieve the above-mentioned object, the present invention searches for a broadcasting station of a receiving channel different from that of a receiving station which is currently receiving a television broadcast and sets the same broadcasting contents as the receiving station. In a television network follow system in which the receiving channel is switched to a switching station having a field strength higher than that of the receiving station, the receiving station is currently receiving the signal when switching from the receiving station to the switching station. Means for turning off the signal on the receiving station side when the vertical synchronizing signal of the video signal of the receiving station is detected, and subsequently turning on the signal on the switching station side when detecting the vertical synchronizing signal of the video signal of the switching station .

[0006]

According to the above means, when switching from the receiving station to the switching station, the screen is not switched while the scanning line is sweeping the screen, so that the TV screen is not displayed when the TV network follow system is operating. There will be no noise on the screen and the screen will not shift.

[0007]

Embodiments of the present invention will be described with reference to the drawings. Figure 1
FIG. 1 is a configuration diagram of a television network follow system according to an embodiment of the present invention. The video detection circuit 3 and the audio detection circuit 5 are connected to the output of the first TV front end 1, and the video detection circuit 4 is connected to the output of the second TV front end 2.
The voice detection circuit 6 is connected. The two television front ends 1 and 2 can also switch receiving channels by a switching control circuit 10.

The outputs of the two video detection circuits 3 and 4 are both input to the video signal switching circuit 7, and the two audio detection circuits 5 and 5 are provided.
Both outputs of 6 are input to the audio signal switching circuit 8. The video signal switching circuit 7 and the audio signal switching circuit 8 have two switches 71, 72 and 81, 82, respectively, and switch between the two input video signals or two audio signals to set the television front ends 1 and 2. The video signal and the audio signal obtained from either one of the above are output. In addition, each switching circuit 7,
8 is switched by the switching control circuit 10.

Further, the outputs of the voice detection circuits 5 and 6 are input to the voice comparison circuit 9, and the voice comparison circuit 9 matches the switching control circuit 10 when the voice signals of the two voice detection circuits 5 and 6 match. Output a signal. In the switching control circuit 10,
In addition to the input of the coincidence signal from the voice comparison circuit 9,
The respective reception levels of the audio detection circuits 5 and 6 and the vertical synchronization signal which is a frame synchronization signal of each video signal detected by the video detection circuits 3 and 4 are input. A memory 11 is connected to the switching control circuit 10.

The operation of the network follow system configured as above will be described with reference to the flowchart of FIG. For starters, currently the first TV frontend 1
The first switch 7 of the video signal switching circuit 7 and the audio signal switching circuit 8 is receiving the reception channel set to
1, 81 are turned on, and the second switches 72, 82 are turned off.

When the network follow system starts to operate, in step S11, the second television front end 2 sequentially searches for a reception channel different from the channel (frequency) which the first front end 1 is currently receiving. To do. Until the search for all channels is completed, the process goes through step S12 and proceeds to step S13. In step S13, it is determined whether or not there is a broadcasting station on the channel. If there is no broadcasting station, the process returns to step S11 to search for the next receiving channel, and if there is a broadcasting station, step S14. Go to.

In step S14, it is determined whether the broadcast content of the station matches the broadcast content of the station currently being received. The match or non-match of the broadcast contents is determined by the audio comparison circuit 9 by comparing the audio signals obtained from the two audio detection circuits 5 and 6. If the two audio signals do not match, it is determined that the broadcast contents do not match, the process returns to step S11 to perform the next search, and if the broadcast contents match, the process proceeds to step S15. In step S15, the channel (or frequency) of the same station is stored in the memory 11. The above operation is repeated,
When it is determined in step S12 that the search has been completed for all channels, the process proceeds to step S16.

In step S16, the same station stored in the memory 11 is received by the second television front end, and its reception level is compared with the reception level currently being received by the first television front end 1. It Until the comparison of all the same stations stored in the memory 11 is completed, the process proceeds from step S17 to step S18 and the memory 1
When the comparison of all stations within 1 is completed, step S1
It returns from 7 to step S11.

In step S18, it is determined whether the reception level of the same station is higher than the reception level of the receiving station. When the reception level of the receiving station is higher than the reception level of the same station, the switching between the stations is not performed, the process returns to step S16, and the comparison with the reception levels of other same stations stored in the memory 11 is performed. . When it is determined in step S18 that the reception level of the same station is higher than the reception level of the reception station, the process proceeds to step S19. In the following steps, that same station
It is treated as a switching station that is switched from the receiving station that is currently receiving.

In step S19, the first video detection circuit 3 on the receiving station side waits until a vertical synchronizing signal which is a frame synchronizing signal is output. When the vertical synchronizing signal is output, in step S20 each switching circuit 7 , 8 connected to the receiving station side are turned off. Next, in step S21, the process waits until the vertical synchronizing signal is output from the second video detection circuit 4 on the switching station side, and when the vertical synchronizing signal is output, switching of the switching circuits 7 and 8 is performed in step S22. The switches 72 and 82 connected to the station side are turned on.

FIG. 3 and FIG. 4 show the relationship of each video signal when the switching operation is performed. FIG. 3 shows a case where the phase of the video signal of the switching station is behind the receiving station, and FIG. 4 shows a case where the phase of the video signal of the switching station is ahead of the receiving station. In each figure, (a) is a video signal of the receiving station, (b) is a video signal of the switching station, and (c) is output to the screen when the frequency change from the receiving station to the switching station is instructed at time A. Represents a video signal. As is clear from the figure, in either case, switching from the receiving station to the switching station is not performed while the scanning line is sweeping the screen, so noise may occur on the screen or the screen may shift. There is nothing to do.

Thereafter, the process returns to step S11 and the above-described operation is repeated. If the second front end 2 side receives the broadcast due to the switching of the switching circuits 7 and 8, in steps S11 to S22 in the flowchart described above, the second front end 2 side is the receiving station side. Therefore, the first front end side is used for the search.

[0018]

According to the present invention, it is possible to obtain a television network follow system in which noise does not occur on the screen or the screen is displaced when the receiving channel is switched.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a television network follow system according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the system shown in FIG.

FIG. 3 is a waveform diagram (part 1) of each video signal in FIG.

FIG. 4 is a waveform diagram (part 2) of each video signal in FIG.

[Explanation of symbols]

 1, 2 ... Front end 3, 4 ... Video detection circuit 5, 6 ... Audio detection circuit 7 ... Video switching circuit 8 ... Audio switching circuit 9 ... Audio comparison circuit 10 ... Switching control circuit 11 ... Memory

Claims (1)

[Claims] 1. A station that searches for a broadcast station of a reception channel different from that of a reception station that is currently receiving a television broadcast, has the same broadcast content as the reception station, and has an electric field strength higher than that of the reception station. Received when the frame synchronization signal of the video signal of the receiving station currently being received is detected when switching from the receiving station to the switching station in the television network follow system that switches the receiving channel to the switching station with strength. A television network follow system comprising means for turning off a signal on the station side and subsequently turning on the signal on the switching station side when a frame synchronization signal of a video signal of the switching station is detected.