JP2006013689A - Broadcast channel detecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a broadcast channel detecting apparatus capable of reducing a channel search time much more than that of prior arts. <P>SOLUTION: The broadcast channel detecting apparatus comprises: a level discrimination means 21 for discriminating whether or not a reception level is greater than a threshold value (TH); a synchronization discrimination means (22) for furthermore discriminating whether or not frame synchronization is finished when it is discriminated that the reception level is greater than the threshold value (TH); and a channel search means (23) for shifting to a channel whose searching is not finished and continuing detection of the broadcast channel when it is discriminated that a reception level is smaller than a threshold value (TH) or when it is discriminated that the frame synchronization is not complete. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a broadcast channel for searching and detecting a channel that actually provides a broadcast, that is, a broadcast channel, from a plurality of prescribed channels in cooperation with a broadcast receiver such as a digital broadcast receiver. The present invention relates to a detection device.

  The broadcast channel detection device stores in advance a so-called “channel search” in which a plurality of channels are sequentially searched and the above-mentioned broadcast channels are detected, and channels of a plurality of broadcast stations that can be received in each region are stored in advance. Thus, it is an indispensable device for executing “auto-preset” that allows a desired broadcast station to be received later by a simple selection operation. In particular, in the case of a digital broadcast receiver that needs to quickly capture only a broadcast channel from a very large number of prescribed channels, such as 50 channels, such as a terrestrial digital broadcast receiver and a satellite digital broadcast receiver. Channel detectors play an important role.

As a conventional basic element constituting this broadcast channel detection device,
a) Tuner tuning department;
b) a mode / guard search unit;
c) an OFDM frame synchronization unit;
There is.

  The tuner channel selection part a) is a circuit part for individually receiving a prescribed plurality of channels one by one, and is a front end comprising a so-called high frequency amplification part, frequency conversion part, filter and the like.

  The mode / guard search unit of b) receives a frame signal received by an OFDM (Orthogonal Frequency Division Multiplexing) reception system suitable for configuring a digital broadcast receiver, and (i) the above “mode”, that is, It is searched in which of the various transmission modes, such as mode 1, mode 2, and mode 3, whether the frame signal has been received. (Ii) The “guard” is adjacent to a so-called effective symbol. This is a circuit portion for searching for the appearance phase of a so-called guard interval for preventing interference with an effective symbol.

  The OFDM frame synchronization unit of c) is one important circuit part constituting the OFDM demodulation unit in the OFDM receiver. If the frame synchronization is established for the reception signal in the selected channel, this reception signal is It is confirmed that the received signal is any broadcast wave. After this confirmation, the OFDM demodulation circuit performs OFDM demodulation through an FFT (Fast Fourier Transformer) that converts the received signal from a signal on the time axis to a signal on the frequency axis. Further, composite processing by an MPEG (Moving Picture Experts Group) decoder and further video / audio reproduction processing are performed to provide video (TV) information and audio information to the user.

  Since the broadcast channel detection apparatus targeted by the present invention is used for the above-mentioned “channel search”, for example, it is important to find a broadcast channel at high speed. If this search is not performed quickly, the user is uncomfortable.

  In addition, as a well-known document relevant to this invention, there exist the following [patent document 1]-[patent document 4], for example.

[Patent Document 1] detects the presence or absence of a null symbol when the IF signal level exceeds a reference.
[Patent Document 2] relates to frame synchronization such as detecting a null symbol period at a timing at which a minimum level is detected,
[Patent Document 3] performs reproduction synchronization by detecting a null symbol level.
[Patent Document 4] checks whether or not synchronization pull-in is possible when the signal level of a channel exceeds a certain value at the time of digital terrestrial reception by CATV.

Japanese Patent Laid-Open No. 11-308191 Japanese Patent No. 3342967 Japanese Patent Laid-Open No. 2001-186101 Japanese Patent No. 3338810

  As described above, in the broadcast channel detection device, it is necessary to capture a broadcast channel from a large number of channels at high speed. Therefore, the “channel search time” required for each of the above-described components a), b) and c) is examined as follows. The estimated time is shown.

  a) The tuner tuning time is “50 ms”. However, this is the case when the PLL is synchronized with the tuner.

  b) The mode / guard search time is “100 ms”. However, it is the total mode / guard search time in the prescribed 12 ways. Note that ¼ of the frame signal length in the OFDM scheme is the guard interval. Further, the frame signal length under the mode 3 is the longest, half the length under the mode 2, and ¼ length under the mode 3 under the mode 1.

  c) The establishment time of OFDM frame synchronization is “205 to 411 ms”. This is a period of 1 to 2 frames. The reason for detecting two frames, that is, frame synchronization twice, is as follows.

  First, the case where one frame is sufficient is a case where the head of the frame has just arrived after the input of the received signal is started. However, when the head of the frame has already passed immediately before the input of the received signal, the frame synchronization detection operation must be started after waiting for the head of the next frame to come. In this case, the above two frames are required.

  Further, “205 to 411 ms” of c) is a numerical value obtained for the longest frame having a 1 / 4-length guard interval in the case of “mode 3”. That is, the above 205 ms is a numerical value obtained as 204 symbols × 1.25 ms = 205 ms.

  After all, the total search time of the broadcast channel, which is the sum of the tuner selection time (= 50 ms), the mode / guard search time (= 100 ms), and the OFDM frame synchronization establishment time (= 205 to 411 ms), “355 to 561 ms”. Therefore, the average time is “458 ms”. This is about 0.5 seconds. For example, if there are 50 channels, the time required to complete the all channel search is at least 25 seconds, which is extremely long. This is a problem.

  Accordingly, in view of the above problems, an object of the present invention is to provide a broadcast channel detection apparatus that can perform channel search at a higher speed than the conventional one.

  FIG. 1 is a basic configuration diagram of a broadcast channel detection apparatus according to the present invention.

  In this figure, reference numeral 10 at the left end represents a general digital broadcast receiver, and its schematic configuration is an antenna 11 for receiving a radio channel and a desired channel (broadcast) among a number of receivable channels. ) For selecting a channel), a frame synchronizer 13 for performing frame synchronization on the received signal of the selected channel, and demodulation / decoding for demodulating and decoding the received signal (broadcast signal) after the frame synchronization. And a display DISP and a speaker SP that allow the user to view the video information and audio information thus reproduced. The demodulation / decoding unit 14 is represented by the above-described OFDM demodulation circuit 15 and MPEG decoder 16 that are normally used in a digital broadcast receiver.

  The present invention relates to a broadcast channel detection apparatus (represented by reference numeral 20 at the left end of FIG. 1) for performing a channel search in cooperation with such a digital broadcast receiver 10. According to the present invention, the broadcast channel detection apparatus 20 includes at least a level determination unit 21, a synchronization determination unit 22, and a channel search unit 23. In FIG. 1, the broadcast channel detection device 20 is described separately from the digital broadcast receiver 10 for easy understanding, but in actuality, these are configured integrally.

Here, when the respective functions of the means 21, 22, and 23 are clarified,
The level determination means 21 determines whether the reception level of the reception signal of the broadcast wave is greater (<) or smaller (>) than a predetermined threshold TH,
Only when it is determined that the reception level is higher than the threshold value TH (TH <), the synchronization determination unit 22 completes the frame synchronization executed by the frame synchronization unit 13 for the received signal (“OK”). Whether or not ("incomplete")
When the level determination unit 21 determines that the reception level is lower than the threshold value TH (TH>) or the synchronization determination unit 22 does not complete frame synchronization (“incomplete”). When the determination is made, it operates on the channel selection means 12 to shift to a channel for which search has not been completed and to continue detecting the broadcast channel.

  The broadcast channel detection device 20 further preferably includes a channel number list memory 31 and a broadcast information list memory 32 shown in FIG.

  The channel number list memory 31 uses the channel search means 23 to search all the channels that have been broadcast according to the determination result of the synchronization determination means 22 in the series of channel searches until the search for all possible channels is completed. The number is saved.

  Also, the broadcast information list memory 32 has all the channel numbers determined to be broadcast according to the determination result of the synchronization determination means 22 in the series of channel searches before the channel search means 23 finishes searching for all possible channels. Correspondingly, broadcast information such as a broadcast station name and a program name obtained by demodulating / decoding the received signal (broadcast signal) after the frame synchronization described above by the demodulation / decoding unit 14 is stored.

  Conventionally, for example, if there are 50 channels, the broadcasting is actually performed only on about half or less of the channels, but the presence or absence of broadcasting is checked for every channel. Moreover, in order to check the presence / absence of broadcasting, it is necessary to keep track of the establishment of the above-described frame synchronization, and therefore it takes a maximum of 400 ms.

  On the other hand, the present invention pays attention to a certain fact and avoids the necessity of checking the establishment of the frame synchronization one by one as much as possible, thereby speeding up the channel search. Here, the above fact is that if the reception level of each channel is examined, it is possible to roughly find out the presence or absence of broadcasting without having to know until the establishment of frame synchronization.

  For this purpose, the level determination means 21 is introduced to estimate that there is no broadcast for a channel having a reception level that does not exceed the predetermined threshold TH, and the subsequent frame synchronization process is omitted. As a result, the total search time for all channels can be greatly reduced.

  In this case, even a channel having a reception level exceeding a predetermined threshold TH may not be due to actual broadcasting. In such a case, the determination result by the synchronization determination unit 22 is “incomplete”, and the channel selection unit 12 is activated by the channel search unit 23 as in the case where the level determination result is “TH>”. Move to a channel that has not been searched.

  As a result, data to be stored in the channel number list memory 31 can also be collected at a higher speed than in the past. The same applies to the broadcast information list memory 32 that stores data such as broadcast station names and program names.

  Note that the speeding up of the channel search described above becomes more remarkable when the digital broadcast receiver 10 has a diversity configuration including a plurality of branches (described later). This is because, if a search for a plurality of channels is performed simultaneously for all the branches so that each of the plurality of branches is in charge of the corresponding channel, the search channels can be shifted one after another in units of a plurality of channels.

  Furthermore, the user can view a favorite broadcast in a shorter time than before. In addition, if the above diversity configuration is adopted, while a channel search is being performed, if there is a favorite broadcast, the user immediately starts watching in that branch, and in a branch other than that branch, the channel that has not been searched continues. You can also continue the search.

  FIG. 2 is a diagram showing an actual configuration example of the present invention for a receiver having a single branch configuration. Throughout the drawings, similar components are denoted by the same reference numerals or symbols.

  The digital broadcast receiver 10 in this figure has a non-diversity configuration consisting of a single branch, and a frequency converter (RF / IF) 41 that forms a tuner (channel selection means 12 in FIG. 1) for the received signal from the antenna 11. A level detection unit 42 that detects the reception level of the received signal, the frame synchronization unit 13 described above, and a fast Fourier transform process applied to the broadcast signal that has passed through the frame synchronization unit 13 to convert the broadcast signal into a time axis An FFT unit 43 that converts the upper signal into a signal on the frequency axis and passes it to the OFDM demodulation circuit 15 in the next stage. Since the subsequent stage from the OFDM demodulating circuit 15 is the same as the configuration of FIG.

  On the other hand, a broadcast channel detection apparatus 20 according to the present invention is shown on the lower side of FIG. 2, but according to the example of this figure, the level determination means 21, synchronization determination means 22, and channel search means 23 described above. Are formed as the microcomputer 44. That is, these means 21, 22 and 23 are realized by software processing by the microcomputer 44.

  The channel number list memory 31 and the broadcast information list memory 32 shown in FIG. 1 are respectively formed in predetermined areas in the memory unit 45 that cooperates with the microcomputer 44 in FIG.

  After all, in the example of FIG. 2, the digital broadcast receiver 10 is composed of a single branch having a non-diversity configuration, and a set of level determination means 21, synchronization determination means 22, and channel search means 23 for this single branch. It has.

  FIG. 3 is a diagram showing an actual configuration example of the present invention with respect to a receiver having a diversity configuration.

  The digital broadcast receiver 10 of this figure has, for example, a frequency division type diversity configuration including a plurality of branches B1, B2,... Bn, and each of these branches (B1, B2,... Bn) is substantially the same as FIG. It has the composition of. That is, the antenna 11, the frequency conversion unit (RF / IF) 41 that forms the channel selection unit 12 in FIG. 1, the level detection unit 42 that detects the reception level of the reception signal from the antenna 11, and the frame synchronization unit 13 described above. Then, a fast Fourier transform process is applied to the broadcast signal that has passed through the frame synchronizer 13, and the broadcast signal is converted from a signal on the time axis to a signal on the frequency axis and passed to the OFDM demodulation circuit 15 in the next stage. An FFT unit 43. Since the subsequent stage from the OFDM demodulating circuit 15 is the same as the configuration of FIG.

  Therefore, the difference from FIG. 2 is that the diversity part 46 is inserted. As is well known, the diversity unit 46 synthesizes the reception signals for all the branches so as to give a larger weighting coefficient to the reception signal from the branch with the higher reception level, and then supplies it to the OFDM demodulation circuit 15 at the next stage. To do.

  On the other hand, the broadcast channel detection device 20 according to the present invention is shown on the lower side of FIG. 3, but the example of this diagram is similar to FIG. 2 in the above-described level determination means 21, synchronization determination means 22, The channel search means 23 is formed as a microcomputer 44, and these means 21, 22 and 23 are realized by software processing by the microcomputer 44.

  However, the microcomputer 44 in FIG. 3 inputs the level detection signals (“level information”) from the branches B1, B2,... Bn and the respective synchronization status signals (“synchronization information”) in a lump. Therefore, the level determination means 21 exists for each branch. Similarly, both the synchronization determination means 22 and the channel search means 23 exist for each branch, and each output of the channel search means 23 is transferred to the frequency converter 41 of the corresponding branch. The other memory units 45 are as described in FIG.

  Eventually, when the digital broadcast receiver 10 has a diversity configuration composed of a plurality of branches, the level determination means 21 and the synchronization determination means 22 make the respective determinations for each branch, and the channel search means 23 is set for each branch. I have.

  2 and FIG. 3, the configuration shown in FIG. 2 can be applied to, for example, a home digital broadcast receiver. On the other hand, the configuration shown in FIG. It can be applied to an in-vehicle digital broadcast receiver. As described above, the broadcast detection apparatus 20 according to the present invention can be applied without distinction to the above-mentioned home use and in-vehicle use. Hereinafter, several embodiments will be described as a development form of the broadcast detection apparatus 20 according to the present invention.

FIG. 4 is a diagram showing a further development of the broadcast detection apparatus according to the present invention.
[Embodiment 1]
The first embodiment relates to the channel selection means 51 shown in FIG. As described above, the result after completing the channel search at high speed is stored in the channel number list memory 31. Therefore, a list of channel numbers in the memory 31 is displayed on a display DISP, for example. The user can then select a favorite channel from among them. The channel selection means 51 performs this selection, for example, a means for performing an operation such as pressing a key switch around the display DISP or touching a GUI display on the display DISP with a finger.

  Since it is confirmed that there is a broadcast in all of the channels to be selected in this way, the received signal (broadcast signal) after the frame synchronization by the frame synchronization unit 13 is sent to the OFDM demodulator 15 or the user. The video / audio obtained through the MPEG decoder 16 can be viewed through the display DISP and the speaker SP.

As described above, the present embodiment 1 has the channel selection means 51 for displaying the contents of the channel number list memory 31 on the display and selecting a desired one from the display, and for the selected channel after frame synchronization. The digital broadcast receiver 10 provides the user with the video / audio obtained by demodulating and decoding (14) the received signal.
[Embodiment 2]
This embodiment relates to the broadcast selection means 52 shown in FIG. As described above, the channel search is completed at a high speed and the result obtained through the MPEG decoder 16 is stored in the broadcast information list memory 32. Therefore, a list of broadcast station names and program names in the memory 32 is displayed on a display DISP, for example. Then, the user can select a favorite broadcast station or program from the list. The broadcast selection means 52 performs this selection, and as in the second embodiment, for example, a key switch around the display DISP is pressed, or a GUI display on the display DISP is touched with a finger. Means.

  Thus, the user can view the video / audio obtained from the broadcast signal after the frame synchronization by the frame synchronization unit 13 through the OFDM demodulation circuit 15 and the MPEG decoder 16 through the display DISP and the speaker SP.

As described above, the present embodiment 2 has the broadcast selection means 52 for displaying the contents of the broadcast information list memory 32 on the display and selecting a desired one from the display. The digital broadcast receiver 10 provides the user with video / audio obtained by demodulating and decoding (14) the received signal.
[Embodiment 3]
In the third embodiment, a feature can be found in the channel search means 23 in FIG. This takes advantage of the diversity configuration composed of a plurality of branches (B1, B2,... Bn). Similar to Embodiments 1 and 2 above, video / audio is provided to the user, but in the case of Embodiment 3, video / audio is provided to the user when all channel searches are completed. Instead, the video / audio is immediately provided to the user when a channel that is first determined to be broadcast is found. In this case, only the branch that is selecting the channel occupies the OFDM demodulator circuit 15 and the MPEG decoder 16, but the execution of the channel search itself requires the OFDM demodulator circuit 15 and the MPEG decoder 16. Therefore, channel search can be continued for other branches other than the currently selected branch (broadcasting branch), and the search for all remaining channels can be continued at the same time while broadcasting to the user. Is obtained. However, since the diversity effect does not work for broadcasting from the selected branch, the image quality and the like may be deteriorated until the search of all remaining channels is completed. However, it is only degraded for at most several tens of seconds to complete the search. Therefore, during that time, for example, a message such as “Now on channel search” may be displayed on the display DISP and the user may wait for a while.

As described above, in the third embodiment, for the one branch that is first determined that the frame synchronization is completed by the synchronization determination unit 22, the video / audio of the channel is provided from the digital broadcast receiver 10 to the user. For the remaining branches, the channel search means 23 continues the search for the unfinished channel.
[Embodiment 4]
In the third embodiment, video / audio is provided to a user in a certain branch while channel search is continued simultaneously in the remaining other branches. Therefore, the embodiment 3 is performed only under the diversity configuration of FIG. Is possible. That is, the above cannot be performed with the non-diversity configuration of FIG.

Thus, in the fourth embodiment, when it is first determined by the synchronization determining means 22 that the frame synchronization has been completed, the video / audio of the channel is provided to the user from the digital broadcast receiver 10, and the channel search means 23 Stop searching for unsearched channels.
[Embodiment 5]
The fifth embodiment relates to the migration specifying means 53 shown in FIG. Referring back to Embodiment 3 above, in this Embodiment 3, any channel that was initially broadcasted is selected and the broadcast is provided to the user.

  However, if the user does not like the initial broadcast, it is desirable to give the user more options. In view of the fact that in the third embodiment, the channel (branch) of the first broadcast is selected and the channel search is continued for the remaining branches, the channel of the channel captured during the continuation is also transferred to the transition specifying means 53. For example, the selection can be made by a key switch, or the first broadcast is left as it is.

Thus, in the fifth embodiment, video / audio is provided to the user from the digital broadcast receiver 10 and (i) the channel can be left as it is, or (ii) when there is another channel for which frame synchronization has been completed. The transition designating means 53 for designating whether to transition to a channel is provided.
[Embodiment 6]
The sixth embodiment also relates to the migration specifying means 53 of the fifth embodiment. Referring back to Embodiment 4 above, since it is a non-diversity configuration, that is, a single branch configuration, it is not possible to select broadcasts one after another as in Embodiment 5 above. That is, either the search is stopped and the first broadcast is viewed as it is, or the first broadcast is stopped and the search for the next channel is resumed.

Thus, in the sixth embodiment, (i) video / audio is provided to the user from the digital broadcast receiver 10 and the search is stopped and the channel is left as it is, or (ii) a search for a channel for which search has not been completed. Whether to migrate is designated by the above-mentioned migration designating means 53.
[Embodiment 7]
The seventh embodiment relates to the above-described broadcast selection means 52 in FIG. 4 and the image memory 54 shown in FIG. In the embodiments so far, after searching all channels, the channel number or the broadcast station name / program name is only presented to the user for the channel being broadcast. However, in the seventh embodiment, the video obtained through the demodulation / decoding unit 14 is temporarily stored as a still image without being displayed on the display every time it is determined that there is a broadcast. The memory for the storage is the image memory 54 described above.

  After the search for all channels is completed, the still images corresponding to each broadcast stored in the image memory 54 are displayed on the display DISP in the form of thumbnails (many pieces of images arranged in a matrix) and displayed to the user. To select one of your choices. For the user, it is possible to select a desired broadcast by looking at an actual image, so that there is an advantage that one broadcast can be selected accurately.

As described above, in the seventh embodiment, the received signal (broadcast signal) after the frame synchronization by the frame synchronization unit 13 is demodulated / decoded for each of all the channels determined to be broadcast according to the determination result of the synchronization determination unit 22 ( 14) each of the images obtained in the above is temporarily stored as still images in the image memory 54, and a series of still images from the image memory 54 are provided to the user from the display DISP of the digital broadcast receiver 10 in a thumbnail display format. Is selected by the broadcast selection means 52.
[Embodiment 8]
As described above, the broadcast channel detection device 20 is an indispensable device for executing “auto-preset”, and this auto-preset unit is denoted by reference numeral 55 in FIG. Although the auto preset unit itself is well known, the auto preset operation can be completed in a shorter time than in the prior art under the high-speed channel search of the present invention described above.

  As described above, in the eighth embodiment, in the digital broadcast receiver 10 including the auto preset unit 55, the contents of the channel number and the broadcast station name in the information stored in the broadcast information list memory 32 with respect to the auto preset unit 55 are described. Set the to high speed.

  The present invention can be applied to a digital broadcast receiver and is a useful means when a high-speed channel search is required. This is particularly useful in the case of a multi-branch diversity configuration.

1 is a basic configuration diagram of a broadcast channel detection apparatus according to the present invention. It is a figure which shows the example of 1 structure of this invention about the receiver of a single branch structure. It is a figure which shows the example of 1 structure of this invention about the receiver of a diversity structure. It is a figure which shows the further extended form of the broadcast channel detection apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Digital broadcast receiver 12 ... Channel selection means 13 ... Frame synchronization part 14 ... Demodulation / decoding part 15 ... OFDM demodulation circuit 16 ... MPEG decoder 20 ... Broadcast channel detection apparatus 21 ... Level determination means 22 ... Synchronization determination means 23 ... Channel Search means 31 ... Channel number list memory 32 ... Broadcast information list memory 41 ... Frequency converter (RF / IF)
42 ... Level detection unit 43 ... FFT unit 44 ... Microcomputer 45 ... Memory unit 46 ... Diversity unit 51 ... Channel selection unit 52 ... Broadcast selection unit 53 ... Transition designation unit 54 ... Image memory 55 ... Auto preset unit

Claims (13)

A broadcast channel detection device for performing a channel search in cooperation with a digital broadcast receiver,
Level determination means for determining whether the reception level of the reception signal of the broadcast wave is larger or smaller than a predetermined threshold;
Synchronization determination means for further determining whether or not the frame synchronization executed for the received signal is completed when it is determined that the reception level is greater than the threshold;
When the level determination means determines that the reception level is lower than the threshold value, or when the synchronization determination means determines that frame synchronization is not completed, the channel shifts to an incomplete search channel. Channel search means to continue detecting broadcast channels;
A broadcast channel detection apparatus comprising:   When the digital broadcast receiver has a diversity configuration including a plurality of branches, the level determination unit and the synchronization determination unit perform determination for each branch unit, and the channel search unit for each branch unit. The broadcast channel detection apparatus according to claim 1, further comprising:   The digital broadcast receiver includes a single branch having a non-diversity configuration, and includes a set of the level determination unit, the synchronization determination unit, and the channel search unit for the single branch. The broadcast channel detection device according to 1.   A channel number list memory for storing channel numbers determined to be broadcast according to the determination result of the synchronization determination means in the series of channel searches before the channel search means finishes searching for all possible channels; The broadcast channel detection apparatus according to claim 2 or 3, characterized in that:   The received signal after the frame synchronization corresponding to the channel number determined to be broadcasted by the determination result of the synchronization determining means in the series of channel searches until the channel search means finishes searching all possible channels. 4. The broadcast channel detection apparatus according to claim 2, further comprising: a broadcast information list memory for storing broadcast information such as broadcast station names and program names obtained by demodulating and decoding the broadcast information.   It has channel selection means for displaying the contents of the channel number list memory and selecting a desired one from among the contents, and for the selected channel, the received signal after frame synchronization is demodulated and decoded. 5. The broadcast channel detection apparatus according to claim 4, wherein the video / audio is provided to a user from the digital broadcast receiver.   Broadcast selection means for displaying the contents of the broadcast information list memory and selecting a desired one from the contents, and obtaining and decoding the received signal after the frame synchronization for the selected broadcast 6. The broadcast channel detection apparatus according to claim 5, wherein the video / audio is provided to a user from the digital broadcast receiver.   For the one branch that is first determined that the frame synchronization has been completed by the synchronization determination means, the digital broadcast receiver provides the user with the video / audio of the channel, while for the remaining branch, the channel search 3. The broadcast channel detection apparatus according to claim 2, wherein the search is continued by the means for the unfinished channel.   In the single branch, when the synchronization determination unit first determines that the frame synchronization is completed, the digital broadcast receiver provides video / audio of the channel to the user, and the channel search unit does not perform the search. 4. The broadcast channel detection apparatus according to claim 3, wherein the search for the completed channel is stopped.   Transition designation means for providing the video / audio to the user from the digital broadcast receiver and designating whether the channel should remain as it is, or when there is another channel for which the frame synchronization has been completed. The broadcast channel detection apparatus according to claim 8, comprising:   A transition designating unit for providing the video / audio to the user from the digital broadcast receiver and designating whether to stop the search and leave the channel or to shift to a search for a channel for which the search has not been completed; The broadcast channel detection apparatus according to claim 9.   An image memory for temporarily storing each video obtained by demodulating / decoding the received signal after frame synchronization as a still image for each of all channels determined to be broadcast according to the determination result of the synchronization determination means 6. The apparatus according to claim 5, further comprising broadcast selection means for providing the user with the series of still images from the image memory in a thumbnail display format from the digital broadcast receiver and selecting one of them. Broadcast channel detection device.   The digital broadcast receiver includes an auto-preset unit, and sets the channel number and the content of the broadcast station name in the information stored in the broadcast information list memory to the auto-preset unit. Item 6. The broadcast channel detection device according to Item 5.

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