JPH03280613A - Same program tracing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Application Field) The present invention relates to a same program tracking device suitable for a television receiver for a mobile body such as a car.

(Prior Art) Recently, light, thin, short, and high-performance television receivers have been developed, and they have come to be used in moving objects such as automobiles. In such television receivers for mobile objects, the field strength received by the antenna changes randomly as the object moves, resulting in deterioration of the S/N ratio and significant deterioration of screen quality. In addition, reception sensitivity may drop significantly and images and audio may be interrupted. Therefore, multiple antennas are provided for one tuner, and the received field strength of each antenna is compared with each other, and the RF multiplied signal from the antenna that always obtains the maximum received field strength is selectively given to the tuner. The receiving method is adopted. This allows stable reception of television broadcasts even when the mobile object is moving.

FIG. 7 is a block diagram showing such a diversity receiving device.

The RF multiplied signal induced in the antennas 1 to 4 is applied to the antenna changeover switch circuit 5. The antenna changeover switch circuit 5 selectively introduces the RF multiplied signals from the antennas 1 to 4 based on a control signal from a level detection/comparison circuit 9, which will be described later, and supplies them to the TV tuner 6. The TV tuner 6 includes an electronic tuning tuner (not shown) and a 1F detection circuit, and selects a channel based on a user's operation and outputs a video signal to an output terminal 7. The video signal from the output terminal 7 is applied to a display device (not shown) and displayed.

Further, horizontal and vertical synchronizing pulses are given from the TV tuner 6 to a timing control circuit 8, and the timing control circuit 8 outputs a timing signal indicating a vertical retrace period to a level detection/comparison circuit 9.

A video signal from the TV tuner 6 is also supplied to the level detection/comparison circuit 9. Based on the timing signal from the timing control circuit 8, the level detection/comparison circuit 9 outputs a control signal to the antenna changeover switch circuit 5 every vertical retrace period to sequentially select antennas 1 to 4, and multiplies the RF frequency from each antenna. The signal reception levels (video signal levels) are compared and control is performed so that the RF multiplied signal from the antenna with the maximum output is selectively introduced until the next vertical retrace period.

In this way, the RF multiplied signal from the antenna that provides the highest reception sensitivity among antennas 1 to 4 is received and tuned.

In this way, stable video and audio can be obtained regardless of random fluctuations in received field strength due to movement of a moving object such as a car.

By the way, the device shown in FIG. 7 is designed to receive the signal of one predetermined channel desired by the user in the best reception condition by switching the antenna, and even if the reception condition deteriorates slowly, The receiving channel is never switched to another channel. When a mobile object moves, it may move from the area of a predetermined broadcasting station to the area of another broadcasting station that is broadcasting the same program. Also, depending on the region, the same program may be broadcast on multiple channels, such as VHF.
It is sometimes broadcast on UHF band channels and UHF band channels. In such a case, by sequentially switching the channels that are broadcasting the same program and selecting the channel with the best reception condition, you can watch the desired program in good condition.
You can watch it.

However, as mentioned above, with the device shown in Fig. 7, even if the receiving electric field strength decreases and the S/N ratio deteriorates due to the moving object moving away from the broadcasting station, the receiving state remains unchanged. will not be switched to another channel that is better. Therefore, in order to obtain a good reception condition, the user has to monitor the reception condition of each channel and change the reception channel, which is extremely complicated. Moreover, the number of channels that can be received is extremely large, and it is difficult to know which channel has the video signal (the right signal channel) while moving, so it takes a long time to monitor the reception status of each channel. In short, there is a problem in that when the received electric field strength changes frequently, it may become impossible to receive television broadcasts satisfactorily.

(Problem to be Solved by the Invention) As described above, in the above-mentioned diversity receiving device, in order to view the desired program in the best condition, the user monitors the reception condition of each channel and broadcasts the same program. However, it is extremely troublesome to have to change the reception channel to another channel within the system, and this monitoring requires a long time, which can sometimes make it difficult to receive good reception.

The present invention has been made in view of such problems, and includes:
Same program tracking allows you to watch the desired program with good reception at all times by automatically selecting the channel with the best reception in a short time from among the channels broadcasting the same program. The purpose is to provide equipment.

[Configuration of the Invention (Means for Solving the Problems) The same program tracking device according to the present invention includes an antenna changeover switch circuit that is selectively introduced based on an RF multiplied signal control signal induced in a plurality of antennas; a master tuner that selects a channel based on a user's operation among the RF multiplied signals from the antenna switching switch circuit, selects a channel based on a channel switching signal, and outputs a video signal to a display device; and a master tuner that outputs the control signal. The antenna selection switch circuit sequentially switches the antennas selected, sequentially introduces the output of each antenna of the master tuner, detects and compares the reception level, and selects the antenna that provides the maximum reception level to the antenna selection switch circuit. a level detection/comparison circuit for selection, a slave channel to which the RF multiplied signal from the antenna changeover switch circuit is applied, a channel determination means for outputting information indicating the channel on which the video signal exists, and a channel from the channel determination means. a channel sequential switching circuit that sequentially switches the receiving channels of the slave tuner based on the information; and a channel sequential switching circuit that sequentially switches the reception channels of the slave tuner, and converts the video signals from the master tuner and the slave tuner into digital signals at timings corresponding to the same position on the screen, respectively. first and second 21i conversion means for digitization, first and second image memories for storing binary data from the first and second binarization means, respectively; an image comparison circuit that outputs a coincidence signal indicating that the same program is being broadcast by the receiving channels of the master tuner and the slave tuner by reading and comparing video signals stored in the image memory of the master tuner; and a field strength comparison circuit that compares the field strength of the receiving channel of the slave tuner and outputs a comparison signal, and the matching signal is input and the field strength of the receiving channel of the slave tuner is adjusted by the comparison signal to that of the master tuner. a program following channel switching circuit that outputs the channel switching signal to switch the receiving channel of the master tuner to the channel being received by the slave tuner when it is shown that the number of receiving channels is greater than the field strength; It is equipped with

(Operation) In the present invention, diversity reception is performed by antenna switching based on the output of the master tuner. On the other hand, in the slave tuner, reception channels are sequentially switched by a channel sequential switching circuit. In this case, the channel determining means selects only the signaled channel. The video signals from the master tuner and the slave tuner are converted into binary data by the first and second binarization means and then given to the first and second image memories, respectively. By comparing the binary data stored in the two image memories, a matching signal is output indicating that the same program as the one being broadcast by the receiving channel of the master tuner is being broadcast by another channel. Since the video signals are compared after being binarized, it is possible to reliably detect the sameness of programs even if the S/N is low. The electric field strength comparison circuit compares the electric field strengths of the reception channels of the master tuner and the slave tuner and outputs a comparison signal. The program following channel switching circuit uses a matching signal and a comparison signal to select the channel with the greater electric field strength between the receiving channel of the master tuner and another channel broadcasting the same program as the program being broadcast on this channel. to be selected by the master tuner. Since the slave tuner selects only signals, the received field strength of each channel can be checked in a short time.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 1 is a block diagram showing an embodiment of the same program tracking device according to the present invention. Components in FIG. 1 that are the same as those in FIG. 7 are given the same reference numerals.

The RF multiplied signal induced in the antennas 1 to 4 is applied to the antenna changeover switch circuit 5. The antenna changeover switch circuit 5 selectively introduces the RF multiplied signals from the antennas 1 to 4 based on the control signal from the level detection/comparison circuit 9 and supplies them to the mask TV tuner 10 and the slave TV tuner 11 . The configuration of the level detection/comparison circuit 9 is the same as the conventional one, and a control signal is outputted to the antenna changeover switch circuit 5 every vertical retrace period according to a timing signal to sequentially select antennas 1 to 4, and The RF multiplied signal reception level (video signal level) is compared, and control is performed so that the RF multiplied signal from the antenna with the maximum output is selectively introduced until the next vertical retrace period.

In this embodiment, two TV tuners 10°11 are employed. The mask TV tuner 10 is a conventional TV
Similar to the tuner 6 (see Fig. 7), it selects a channel based on the input RF multiplied signal based on the user's operation, outputs the video signal to the output terminal 7 and the level detection/comparison circuit 9, and outputs the horizontal and A vertical synchronization pulse is output to the timing control circuit 12. Furthermore, mask T
The V tuner 10 provides a video signal to an A/D conversion circuit 13 and provides an AGC voltage to an electric field strength comparison circuit 17. Also,
The mask TV tuner 10 is also configured to switch channels in response to a channel switching signal from a program following channel switching circuit 22, which will be described later.

On the other hand, the slave TV tuner 11 is controlled by the channel switching circuit 20 to select a channel, and converts the video signal into an A/D converter.
The AGC voltage is applied to the conversion circuit 14, and the AGC voltage is applied to the electric field strength comparison circuit 1.
7, and horizontal and vertical synchronization pulses are supplied to the timing control circuit 12. The channel switching circuit 20 is controlled by the timing control circuit 12 and causes the slave TV tuner 11 to sequentially select signal channels other than the reception channel of the mask TV tuner 10 based on instructions from the search channel determination circuit 23. The search channel determining circuit 23 determines a signal-bearing channel according to the receiving position. That is, CD-ROM
24 stores the locations and broadcast channels of broadcast stations nationwide, and provides these data to the search channel determination circuit 23. Further, the navigation system 25 of the mobile body provides position information of the current position of the mobile body to the search channel determination circuit 23. Search channel determination circuit 23
is designed to determine which channels have signals based on data from the CD-ROM 24 and the navigation system 25.

Further, the channel switching circuit 20 is configured to stop switching channel selection when a match signal is input from an image comparison circuit 21, which will be described later. Note that the timing control circuit 1
2 detects the level of the timing signal indicating the vertical retrace period.
The output to the comparison circuit 9 is the same as in the conventional case.

The A/D conversion circuits 13 and 14, for example,
The line video signal is converted into a digital signal and provided to the binarization circuits 15 and 18. In addition, A/D conversion circuit 13.1
In step 4, video signals at the same position on the screen may be sampled, for example, video signals at a predetermined section on the screen may be sampled.

Binarization circuits 15 and 16 are A/D conversion circuits 13 and 14, respectively.
The output is binarized using a predetermined equivalent value and the binary data is provided to a binary data image memory 18.19. The binary data image memories 18 and 19 store the binarized image data from the binarization circuits 15 and 16 at the timing of the timing signal from the timing control circuit 12, respectively. Image comparison circuit 2
1 reads out and compares the image data stored in these binary data image memories 18 and 19,
The tuners io and il determine whether or not the same program is being broadcast based on the selected channel, and if the same program is being broadcast, a matching signal is output to the channel sequential switching circuit 20 and the program following channel switching circuit 22. do. Note that the operation timing of the image comparison circuit 21 is controlled by the timing control circuit 12.

FIGS. 2 to 5 are explanatory diagrams for explaining image comparison using binary video data. Figure 2 (a) to (c)
show screens a, b, and c, respectively, and FIGS. 3 to 5 show binary data corresponding to FIG. 2 (a> to (C)), respectively.

Now, as shown in FIGS. 2(a) to (C), the screen a,
It is assumed that C is the same screen, and screens a and C are different from the screen shown in FIG. 2(b). In screens a and C, a circle 26 whose horizontal luminance level changes from black to white is displayed at the center of the screen. The video signal of the scanning line 27 at the center of the screen is as shown in FIG. 3(a) and FIG. 5(a).

A/D conversion circuits 13 and 14 convert this video signal into a digital signal, and binarization circuits 15 and 16 binarize this digital signal at a predetermined binarization level and output it. As a result, binary data shown in FIG. 3(b) and FIG. 5(b) is obtained. On the other hand, on the screen, a black level circle 28 is displayed in the vertical center of the screen. The video signal of the scanning line 29 at the center of the screen is as shown in FIG. 4(a). The binarization circuits 15 and 16 perform binarization at a predetermined binarization level, so that two
The value is obtained. The image comparison circuit 21 compares and reverses the binary data of FIGS. 3(b) to 5(b), thereby making it possible to recognize the identity of screens a and C.

The field strength comparison circuit 17 compares the AGC voltages from the TV tuners 10 and 11 when a match signal is output from the image comparison circuit 21. As a result, TV tuner 1
The electric field strengths of the receiving channels of 0.11 are compared, and the electric field strength comparison circuit 17 transfers the comparison signal to the channel switching circuit 20.
and is output to the program following channel switching circuit 22.

The program following channel switching circuit 22 includes an image comparison circuit 21
A coincidence signal is input from the electric field strength comparison circuit 17.
If it is shown by the comparison signal from the slave TV tuner 11 that the electric field strength of the receiving channel of the slave TV tuner 11 is larger than the electric field strength of the receiving channel of the mask T 10, a channel switching signal is output to the mask TV tuner 10. The slave TV channel 11 is configured to select the channel currently selected. In addition, the channel switching circuit 20 determines whether the receiving channel of the mask TV tuner 10 is the slave TV tuner 11 or
If it is shown that the electric field strength is greater than that of the receiving channel of the slave TV tuner 11, a signal for sequentially switching the receiving channel of the slave TV tuner 11 is output.

Next, the operation of the same program tracking device configured as described above will be explained.

The antenna switching operation based on diversity is the same as the conventional one. That is, the level detection/comparison circuit 9 outputs a control signal to the antenna changeover switch circuit 5 during the vertical retrace period, and sequentially and selectively supplies the low RF signals from the antennas 1 to 4 to the mask TV tuner 10. The video signals from the mask TV corner 10 that are input to the division are compared, and the RF signal from the antenna that obtains the maximum output among the antennas 1 to 4 is determined.
The low signal is selectively introduced until the next vertical retrace period.

On the other hand, the RF low signal from the antenna changeover switch circuit 5 is also applied to the slave TV tuner 11 .

The slave TV tuner 11 is controlled by the channel switching circuit 20 and sequentially selects channels other than the reception channel of the mask TV tuner 10. When the search channel determination circuit 23 supplies data indicating the signaled channel to the channel switching circuit 20, the slave TV tuner 11 receives only the signaled channel. Since the slave TV tuner 11 does not need to tune all channels, it can tune all channels with signals in a short time.

Video signals from the TV tuners 10.11 are provided to A/D conversion circuits 13.14, respectively. A/D conversion circuit 13,
14 converts the video signal of one predetermined line into a digital signal and supplies it to the binarization circuits 15 and 16.

Binarization circuits 15 and 16 are A/D conversion circuits 13 and 14, respectively.
The digital signal from is binarized at a predetermined binarization level, and the binary data is provided to the binary data image memories 18 and 19 for storage. The image comparison circuit 21 reads the binary data stored in the binary data image memories 18 and 19 and performs comparison. Thereby, the image comparison circuit 21 determines whether the video signals from the TV tuner 10.11 are of the same screen.

If the same program that is currently being broadcast on the receiving channel of the mask TV tuner 10 is also being broadcast on another channel, the slave TV tuner 11 selects this channel and the image comparison circuit A coincidence signal is output from 21 to the channel switching circuit 20 and the program following channel switching circuit 22. Then, the switching of the channel selection of the slave TV tuner 11 is stopped, and the AGC voltages from the TV tuner 10.11 are compared by the electric field strength comparison circuit 17. In this way, the best electric field strength of the reception channel by the mask TV tuner 10 and the best electric field strength of the reception channel by the slave TV tuner 11 are compared. Slave TV tuner 11
The electric field strength of the receiving channel of the mask TV tuner 10
If the field strength is greater than the field strength of the receiving channel, the comparison signal from the field strength comparison circuit 11 causes the program following channel switching circuit 22 to provide a channel switching signal to the mask TV tuner 10 to switch the slave TV tuner 11.
selects the currently selected channel. If the electric field strength of the receiving channel of the mask TV tuner 10 is greater than the electric field strength of the receiving channel of the slave TV tuner 11, the channel switching circuit 20 causes the slave TV tuner 11 to continue switching the channel selection based on the comparison signal.

Thereafter, in the same manner, the slave TV tuner 11 receives all signaled channels under the control of the channel switching circuit 20, and the electric field strength of the receiving channel of the mask TV tuner 10 and other channels broadcasting the same program are changed. be compared. In this way, the mask TV tuner 10 determines which programs are broadcasting the same program. The channel from which the maximum electric field strength can be obtained is always selected.

In this way, in this embodiment, the reception channels of the slave TV tuner 11 are sequentially switched, and the image comparison circuit 2
1 indicates that the programs on the reception channels of TVy-Una 10.11 match, the program follow-up channel switching circuit 22 selects the channel with the larger electric field strength among the two reception channels through the mask TV tuner. 1o so that the desired program can always be viewed in the best condition regardless of fluctuations in radio wave conditions.

For this reason, when adopted in a television receiver for a mobile object, even if the S/N ratio of the program being received deteriorates due to the movement of the mobile object, the channel other than the one currently being received will be When the same program is being broadcast with a good S/N ratio, the receiving channel is automatically switched to a channel with a good S/N ratio, which prevents the screen from deteriorating significantly when the moving object is running. be able to.

In addition, since the slave TV tuner 11 selects only the signaled channel, other channels with good reception conditions can be detected in a short time, which is extremely effective when a mobile object moves long distances at high speed. It is. Furthermore, since the video signal is converted to binary data to determine whether the screens are the same or not, even if the S/N of the video signal deteriorates, the error rate in screen comparison is low and reliable. Channels that are broadcasting the same program can be detected. Therefore, it is effective even when passing through areas where S/N is extremely degraded, and even when the electric field strength of each channel fluctuates rapidly, such as when a moving object moves over a long distance at high speed. A desired program can be viewed in the best condition on either channel in the VHF band or the UHF band.

Furthermore, the binary data image memory 18.19 only needs to store one predetermined line of video signal converted into a digital signal by the A/D conversion circuit 13.14, and a relatively small capacity memory IC can be used. I can do it.

In the example shown in FIG. 2, the scanning line at the center of the screen is used for screen comparison, but as described above, it is clear that the corresponding scanning lines of the two screens may be used. Further, in order to improve the accuracy of screen comparison, a window circuit may be added and comparison may be performed using a predetermined section on the screen.

FIG. 6 is a block diagram showing another embodiment of the present invention.

In FIG. 6, the same parts as in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

In this embodiment, the search channel determination circuit 23,
This embodiment differs from the embodiment shown in FIG. 1 in that the CD-ROM 24 and navigation system 25 are omitted, and a channel sequential switching circuit 30, a switch 31, and a signal channel memory circuit 32 are added. The channel selection of the slave TV tuner 11 is instructed by the channel switching circuit 20 or the channel sequential switching circuit 30 by switching the switch 31.

The channel sequential switching circuit 30 is a timing control circuit 1
2, the slave TV tuner 11 sequentially selects channels other than the channel being received by the mask TV tuner 10.

The signal channel memory circuit 32 stores channel information of signal channels among the selected channels of the slave TV tuner 11. The channel switching circuit 20 causes the slave TV tuner 11 to sequentially select signal channels based on channel information from the signal channel switching circuit 32.

In the embodiment configured in this manner, first, the switch 31 selects the channel sequential switching circuit 30. As a result, the slave TV tuner 11 sequentially tunes all channels other than the reception channel of the master TV tuner 10. The channel information of the signal channels is stored in the signal channel memory circuit 32 in the order of these reception channels. When all channels other than the reception channel of the mask TV tuner 10 are received by the slave TV tuner 11, the switch 31 switches the channel switching circuit 2
Select 0. Then, the channel switching circuit 20 reads the signal channel information from the signal channel memory circuit 32 and causes the slave TV tuner 11 to sequentially select the signal channels. The subsequent operations are similar to the embodiment shown in FIG.

This embodiment does not require expensive devices such as a CD-ROM and a navigation system, and can be constructed at low cost.

[Effects of the Invention] As explained above, according to the present invention, it is possible to select the channel with the best reception condition among the channels broadcasting the same program in a short time, regardless of fluctuations in the radio wave condition. This has the effect that a desired program can be viewed with good reception at all times.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the same program tracking device according to the present invention, FIGS. 2 to 5 are explanatory diagrams for explaining image comparison using binary video data, and FIG. FIG. 7 is a block diagram showing another embodiment of the invention. FIG. 7 is a block diagram showing a diversity receiving device. 1 to 4...Antenna, 5...Antenna changeover switch circuit, 9...Level detection/comparison circuit, 0...Mask TV chiconer, 1...Slave TV tuner, 3.14...A /D conversion circuit, 15.16... Binarization circuit, 7... Electric field strength comparison circuit,

Claims (1)

[Claims] An antenna changeover switch circuit that selectively introduces RF signals induced in a plurality of antennas based on a control signal; and a channel selection based on a user operation among the RF signals from the antenna changeover switch circuit. and a master tuner that selects a channel based on a channel switching signal and outputs a video signal to a display device; a level detection/comparison circuit that causes the antenna changeover switch circuit to select an antenna that provides the maximum reception level by sequentially introducing the output of each antenna, detecting and comparing reception levels; and an RF signal from the antenna changeover switch circuit. a slave tuner to which a video signal is present; a channel determining means for outputting information indicating a channel on which a video signal is present; a channel sequential switching circuit for sequentially switching reception channels of the slave tuner based on channel information from the channel determining means; first and second binarization means that convert video signals from the master tuner and the slave tuner into digital signals and binarize them at timings corresponding to the same position on the screen, respectively; The master tuner reads out and compares the video signals stored in the first and second image memories with the first and second image memories that respectively store the binary data from the two binarization means. and an image comparison circuit that outputs a matching signal indicating that the same program is being broadcast by the reception channels of the slave tuner, and a comparison signal that compares the electric field intensities of the reception channels of the master tuner and the slave tuner. a field strength comparison circuit for outputting; when the coincidence signal is input and the comparison signal indicates that the field strength of the reception channel of the slave tuner is greater than the field strength of the reception channel of the master tuner; A same program tracking device comprising: a program tracking channel switching circuit that outputs the channel switching signal to switch the reception channel of the master tuner to the channel being received by the slave tuner.